Riot Control Agents: Issues in Toxicology, Safety & Health

© 2004 by CRC Press LLC EDITED BY EUGENE J. OLAJOS AND WOODHALL STOPFORD CRC PR E S S Boca Raton London New York Was...

Author: Eugene J. Olajos | Woodhall Stopford M.D.

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© 2004 by CRC Press LLC

EDITED BY EUGENE J. OLAJOS AND WOODHALL STOPFORD

CRC PR E S S Boca Raton London New York Washington, D.C. © 2004 by CRC Press LLC

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Riot Control Agents Issues in toxicology, safety, and health LIST OF CONTRIBUTORS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ix

CHAPTER 1 Introduction and Historical Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eugene J. Olajos and Woodhall Stopford

1

CHAPTER 2 Application and Use of Riot Control Agents Jeanne M. Ditter and Charles S. Heal

. . . . . . . . . . . . . . . . . . . . . . . . . 17

CHAPTER 3 Synthesis and Chemical Analysis of Riot Control Agents Sidney A. Katz and Harry Salem

. . . . . . . . . . . . . . . 25

CHAPTER 4 Biochemistry, Biological Interactions, and Pharmacokinetics of Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Eugene J. Olajos CHAPTER 5 Riot Control Agents and Acute Sensory Irritation Eugene J. Olajos and Woodhall Stopford

. . . . . . . . . . . . . . . . . . . . . 65

CHAPTER 6 Pharmacology/Toxicology of CS, CR, CN, Formulations, Degradation Products, Carriers/Solvents, and Propellants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Eugene J. Olajos and Joan M. Lakoski CHAPTER 7 Pharmacology/Toxicology of Oleoresin Capsicum, Capsaicin, and Capsaicinoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Eugene J. Olajos and Joan M. Lakoski CHAPTER 8 Chronic Toxicity of Riot Control Agents Woodhall Stopford

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

CHAPTER 9 Reproductive and Developmental Toxicology of Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Russell F. Mankes and Kristina M. Mankes CHAPTER 10 Genetic Toxicity of Riot Control Agents Joyce M. Durnford

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

v © 2004 by CRC Press LLC

RIOT CONTROL AGENTS

CHAPTER 11 Human Exposures to Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Woodhall Stopford and Frederick R. Sidell CHAPTER 12 Forensic Aspects of Riot Control Agents Bryan Ballantyne and Harry Salem

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

CHAPTER 13 An Approach for Assessing and Characterizing Risk from the Use of Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 Jacqueline Patterson, Bert Hakkinen, Patricia Nance, Michael Dourson, and B. Jon Klauenberg CHAPTER 14 Occupational Exposures to Riot Control Agents Woodhall Stopford

. . . . . . . . . . . . . . . . . . . . . . 273

CHAPTER 15 Risk Management and Public Health Considerations of Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 Veronique D. Hauschild CHAPTER 16 Environmental Issues Involving Riot Control Agents . . . . . . . . . . . . . . . . . . . 299 Larry E. Erickson, Athertina N. Steinau, Terrie Boguski, and Frederick W. Oehme CHAPTER 17 Genomics, Proteomics, and Computational Toxicology as Future Tools in Assessing Health Hazards of Riot Control Agents . . . . . . . . . . . . . . 317 Akbar S. Khan CHAPTER 18 Issues/Concerns, Needs, Emerging Concepts/Trends, and Advances in Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321 Woodhall Stopford and Eugene J. Olajos APPENDIX A Definitions and Terminology

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

APPENDIX B Decontamination and Medical Management after Exposures to Riot Control Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 APPENDIX C Table of Riot Control Agent Formulations . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

vi © 2004 by CRC Press LLC

List of Contributors Bryan Ballantyne, MD, DSc, PhD 871 Chappell Road Charleston, West Virginia, USA Terrie Boguski, BS(En), MEn Non-Lethal Environmental Evaluation and Remediation Center 104 Ward Hall Kansas State University Manhattan, KS 66506-5102 USA Tel.: (913) 780-3328 Jeanne M. Ditter, BS(En) US Army, Aberdeen Test Center Chief, Non-Lethal Weapons Team ATTN: CSTE-DTC-AT-FC-N 400 Colleran Road Aberdeen Proving Ground MD 21005, USA Tel.: (410) 278-2281 Michael Dourson, PhD Toxicology Excellence for Risk Assessment (TERA) 1757 Chase Avenue Cincinnati, OH 45223, USA Tel.: (513) 542-7475 Joyce M. Durnford, PhD Battelle Columbus Operations 505 King Avenue Columbus, OH 43201-2693, USA Tel.: (614) 424-5060 Larry E. Erickson, PhD Professor of Chemical Engineering and Director Center for Hazardous Substance Research Center, Department of Chemical Engineering, 105 Durland Hall Kansas State University Manhattan, KS 66506-5102, USA Tel.: (785) 532-4313

Bert Hakkinen, PhD European Commission Joint Research Centre Institute of Health and Consumer Protection TP 460, 1-21020 Ispra (VA), Italy Veronique D. Hauschild, MSPH US Army Center for Health Promotion and Preventive Medicine ATTN: MCHB-TS-EES Aberdeen Proving Ground MD 21010, USA Tel.: (410) 436-2407 Charles S. Heal (CAPT) Los Angeles County Sheriff’s Department Special Enforcement Bureau 130 South Fetterly Avenue Los Angeles, CA 90022 Sidney A. Katz, PhD Professor, Department of Chemistry 3154 Penn Street Rutgers University Camden, NJ 08102, USA Tel.: (856) 225-6154 Akbar S. Khan, PhD Research and Technology Directorate US Army Edgewood Chemical and Biological Center Aberdeen Proving Ground MD 21010, USA B. Jon Klauenberg, PhD Associate Director, Air Force Research Laboratory Non-Lethal Weapons Human Effects Center of Excellence Brooks AFB, TX 78235-5368 Tel.: (210) 536-3977

vii © 2004 by CRC Press LLC

RIOT CONTROL AGENTS

Joan M. Lakoski, PhD Assistant Vice Chancellor, Health Sciences and Professor of Pharmacology University of Pittsburgh Medical Center Scaife Hall, 3550 Terrace Street Pittsburgh, PA 15261, USA Tel.: (412) 648-9410 Russell F. Mankes, PhD Associate Professor Department of Environmental Health and Safety Albany Medical College 47 New Scotland Avenue Albany, NY 12208, USA Tel.: (518) 262-5490 Kristina M. Mankes, MD Department of Medicine, University of Maryland, 22 South Greene Baltimore, MD 21201

Eugene J. Olajos, PhD US Army Edgewood Chemical and Biological Center 5183 Blackhawk Road Aberdeen Proving Ground MD 21010, USA Tel.: (410) 436-7306 Jacqueline Patterson, MEn Toxicology Excellence for Risk Assessment (TERA) 1757 Chase Avenue Cincinnati, OH 45223, USA Tel.: (513) 542-7478 Harry Salem, PhD US Army Chemical and Biological Center 5183 Blackhawk Road Aberdeen Proving Ground, MD 21010 Tel.: (410) 436-3034 Frederick R. Sidell, MD Consultant 14 Brooks Road Bel Air, MD 21014, USA

Patricia Nance, MEd, MA Toxicology Excellence for Risk Assessment (TERA) 1757 Chase Avenue Cincinnati, OH 45223, USA Tel.: (513) 542-7487

Athertina N. Steinau, BS, MS, MS Consultant 7302 Paces Park Drive Decatur, GA 30033, USA Tel.: (404) 299-5509

Frederick W. Oehme, DVM, PhD Kansas State University Comparative Toxicology Laboratories 1800 Denison Avenue Manhattan, KS 66506-5606, USA Tel.: (785) 532-4334

Woodhall Stopford, MD, MSPH Division of Occupational and Environmental Medicine, Duke University Medical Center 2200 West Main Street, Suite 600 Durham, NC, 27705, USA Tel.: (919) 286-5744

viii © 2004 by CRC Press LLC

Preface The use of chemicals for riot control and for civilian peacekeeping operations has become a notable feature of modern day society. Riot control agents (RCAs) are substances that have immediate and direct effects on humans. In most circumstances, RCAs are safe when handled correctly and with precautionary and guidance measures. However, because of their wide usage and potential for misuse, adverse effects may occur. There is a rapidly increasing interest in the application/use, health hazards/risks, environmental impact, and risk assessment/characterization/management of RCAs. Moreover, the enhanced awareness by the general public as to the potential risks from RCAs places increased emphasis and importance, if not mandating, the need for knowledgeable scientific, medical, and public health communities as well as a better informed law enforcement community. This volume presents an extensive account of RCAs. The chapters not only cover the biochemistry, chemistry, pharmacology/toxicology, clinical aspects, genotoxicity, and developmental/reproductive effects but also include topics covering application/use, forensic aspects, occupational health considerations, environmental aspects, and risk/regulatory concerns and issues. The comparative and human toxicology of RCAs are presented and discussed in detail. Moreover, the biological effects of RCAs are viewed not only from the perspective of active ingredients but also takes into consideration the perspective of RCA formulations and components such as carriers/solvents. Appendixes are also included – one of which focuses on medical treatment and care. The chapter contributors are distinguished scientists and clinicians from academia, government, and industry recognized for their contributions and prominence in RCA research and involvement in RCA health and safety issues. This book evolved from the need for a single and comprehensive source of information on RCAs and recognition of a growing awareness by health professionals and the general public regarding the potential hazards from RCAs. In view of the extensive use of RCAs, it is hoped that this book will be of value to a wide spectrum of professionals and organizations. We believe this work will be a reference source to toxicologists, pharmacologists, medical and public health professionals, occupational health care specialists, general and emergency room physicians, environmental scientists, chemists and biochemists, regulatory officials, and safety personnel. Further, this volume will serve as an impetus for others to seek a greater and better understanding of RCA biology, chemistry, health issues, and regulatory concerns as well as fostering research and development. The editors would like to pay tribute to each individual author for a substantial contribution achieved at the cost of personal effort and time. We thank also the staff at Taylor & Francis who helped make this publication possible. We are very grateful for the unfailing support, encouragement, and wisdom of Jane Elizabeth Davis and Carolyn Stopford throughout the course of our endeavors. We dedicate this book to you. Eugene J. Olajos Woodhall Stopford

ix © 2004 by CRC Press LLC

CHAPTER

Introduction and Historical Perspectives

1

EUGENE J. OLAJOS1 AND WOODHALL STOPFORD2 1 US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 2

Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, North Carolina

1.1 INTRODUCTION Techniques have been available for many years to deal with civil disturbances and uncontrolled demonstrations – in particular methods involving the utilization of irritant chemical substances. Modalities used in riot control situations are intended to deter, disperse or render temporarily incapacitated those involved in disturbances using minimal physical intervention and reduction of face-to-face conflict between law enforcement or responding personnel and demonstrators. Nonchemical means of riot control and crowd dispersion include the use of water cannon and plastic/rubber bullets – other approaches such as the use of low friction polymers to hinder movement has been suggested as a potentially useful riot control technique. Chemically based means of riot control and crowd dispersion, either in use, under development, or proposed, include the following types of chemical intervention: (1) peripheral sensory irritants (i.e. “tear gases”, oleoresin capsicum (OC, “pepper spray”), (2) dyes, pigments or fluorescent marking paints, (3) persistent obnoxious odor causing substances (malodorants), and (4) nonirritant obscuring smokes (Swearengen, 1966; Pearlman, 1969; Deane-Drummond, 1975; Ballantyne, 1977). Riot control methods are diverse and some have obvious toxicological, medical, operational, or sociological disadvantages and have not been utilized in civil disturbances. Of the aforementioned chemically based riot control technologies, devices/systems based on the peripheral sensory irritants also referred to as “lacrimators,” “harassing agents,” “tear gases” (i.e. chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS)), and “inflammatory agents” (i.e. OC), constitute the mainline riot control agents (RCAs) used by law enforcement and military personnel. A recently developed product for law enforcement use (i.e. CapTor®) contains nonivamide (“synthetic capsaicin”) as the active ingredient and is considered by the manufacturer as an improvement over established defense sprays containing CS, CN, or OC. “Riot control agents” is the collective term used to describe a divergent group of compounds that have been developed for use by law enforcement and military personnel as well as for personal protection. These compounds have been referred to as lacrimators or as “harassing agents” and are commonly called “tear gases” – the latter term a misnomer since these compounds are not gases. Reference to these compounds as “harassing agents” is based on chemically induced localized, uncomfortable sensations (e.g. lacrimation, stinging, burning sensation, rhinorrhea, tightness in the chest) with associated reflexes. The effectiveness of these compounds in crowd control/crowd dispersion derives

1 © 2004 by CRC Press LLC

RIOT CONTROL AGENTS

from their properties as extremely potent lacrimators and highly effective irritants of the mucous membranes and skin. RCAs have been described as nonlethal. Characteristics common to RCAs include: a rapid onset of effect(s), a relatively short duration of action following cessation of exposure and (3) a relatively high safety margin between an irritating dose and the one associated with risk of irreversible effects or death. A synopsis of RCAs currently in use as well as that representative of the early RCAs is given in Table 1.1. The riot control agent CN is still manufactured and used to a limited extent. CS is still frequently employed as a RCA; however, OC (“pepper spray”) is rapidly gaining widespread use among law enforcement personnel. RCAs also constitute the active ingredient(s) of self-defense sprays (“aerosol subject restraints” (ARSs)) – products that are widely used by law enforcement agencies and for personal protection. A discussion on personal defense sprays follows the overview on RCAs as utilized in quelling civil disturbances and in “peacekeeping” operations by law enforcement agencies and in various military applications. As previously mentioned, RCAs comprise a diverse group of compounds. A brief synopsis of the physico-chemical properties of modern RCAs is presented in Table 1.2. For a detailed description and discussion related to the chemistry of RCAs the reader is referred to Chapter 3 by Katz and Salem. Riot control agents are highly potent sensory irritants, which elicit acute site-specific physiological actions affecting the eyes, the pulmonary system, and skin (refer to Figure 1.1). Exposure to RCAs may occur via inhalation, dermal, or oral routes or a combination of these exposure pathways. Pharmacologically, these chemicals interact with sensory nerve receptors associated with mucosal surfaces and the skin at the site of contamination, producing localized discomfort or pain with associated reflexes. Thus, ocular irritation,

TABLE 1.1 RCAs and lacrimators Compound

Ethyl bromoacetateb Camite

Chemical name

Application Codea

Former

Current Intermediate Agricultural chemical Riot control, incapacitant Riot control, incapacitant Riot control, incapacitant Food additive, incapacitant Food additive, incapacitant

EBA CA, BBC

Riot control Riot control

CNc

Ethyl 2-bromoacetate -Bromo--tolunitrile, bromobenzyl cyanide 2-Chloroacetophenone

CN

Riot control

CR

dibenz[b,f]1:4-oxazepine

CR

Riot control

CSc

-Chlorobenzylidene malononitrile OC, “pepper-gas”d

CS

Riot control

(—)f

Food additive

“Synthetic capsaicin”e

(—)f

Food additive

Oleoresinc capsicum Nonivamidec

Notes a Military code or identifier – usually one legitimate code designation. b Chemical intermediate for pharmaceuticals. c Active ingredient in self-defense sprays. d Active component is capsaicin (N-[4-hydoxy-3-methoxy-phenyl)methyl]-8-methyl-6-nonanamide). e Nonivamide (N-[4-hydroxy-3-methoxy-phenyl)methyl] nonanamide). f No military designator.


TABLE 1.2 Physico-chemical and biological properties of common RCAs Physical propertiesa

Compound

Reactivity data

Physical state

Solubility

Stability

Hydrolysis rate

CN

Solid

Insoluble in water

Slow

CR

Solid

CS

Solid

Capsaicinc

Solid

Limited solubility in water; soluble in organic solvents Slightly soluble in water; soluble in organic solvents Slightly soluble in water; soluble in organic solvents

Stable in closed containers Stable in storage

Threshold conc. (mg/m3)

Intolerable conc. (mg/m3)

Lethal conc. (mg/m3)

Instantaneous

1

5

850

Very slow

Instantaneous

0.002

1

10,000

Stable in storage

Slow

Instantaneous

0.004

3

2,500

Stable in storage

Slow

Rapid

(—)

(—)

(—)

Notes a Physico-chemical data: Suzuki and Iwai, 1984; Compton 1987; Sidell, 1997; US Army (CHPPM); n.d. b Threshold values for eye irritation (CN, CR, CS) from Beswick (1983). c Capsaicin is the major pungent ingredient of OC. (—) Data lacking or not available.


Biological valuesb

Rate of action

RIOT CONTROL AGENTS

Tearing, irritation, blepharospasm, burning sensation

Sneezing and coughing, irritation, secretions, lightness in chest

Riot control agents

Burning sensation, erythema, blistering

Nausea, vomiting, diarrhea

Figure 1.1: Acute site-specific pharmacology/toxicology of RCAs.

representative of such responses, results in ocular pain (warning) and excess reflex lacrimation and blepharospasm (protection). Riot control agents act primarily on the eye, which is the most sensitive target organ. Immediate tearing, conjunctivitis, with concomitant blepharospasm (uncontrollable closure of the eyelids), burning sensation, and pain are characteristic symptoms on exposure. Moreover, when dispersed into the eyes, RCAs can cause temporary blindness due to copious lacrimation, which induces disorientation and fear. Although intense lacrimation is a common reaction on exposure to RCA, it must be recognized that these compounds can also elicit varying physiological responses. Thus, respiratory tract and gastrointestinal irritation (i.e. shortness of breath, coughing, wheezing, nausea, and vomiting) are additional manifestations of RCA exposure. It is important to recognize from the biological perspective that RCAs can produce some or all of the effects to a greater or lesser extent. Modern day RCAs are highly effective at low doses and possess low acute toxicity (see Table 1.2). The lethal quantity of CS is estimated to be about 2,600 times as great as the dosage required to produce temporary disabling (Danto, 1987). The margin-of-safety is large – the amount causing an intolerable effect is many times less than the amount producing an adverse effect. Permanent adverse effects usually do not accompany RCAs; however, the risks for deleterious effects,


INTRODUCTION AND HISTORICAL PERSPECTIVES

long-term effects, or even lethality increase with higher exposure levels and/or with greater exposure times. The response is concentration-dependent and ceases on removal of the sensory irritant stimulus. RCAs should possess low acute toxicity and have toxicological and chemical properties that ensure minimal risks. Ideally, in riot control situations as well as in situations other than under riot circumstances, these substances produce “harassing effects” that are relatively benign with a low incidence of casualties and adverse health effects. Generally, it can be stated that modern RCAs possess high safety ratios and deemed safe when used in accordance with prudent practices.

1.2 DISSEMINATION “Peacekeeping” operations vary markedly from those involving only a few individuals to those involving crowds that may comprise large numbers of individuals. Thus, the mode of delivery of RCAs varies and dependent on the situation/scenario. RCAs may be disseminated by pyrotechnic means (i.e. canisters, tear gas grenades) giving rise to an aerosol of irritant. A convenient way of producing an aerosol from relatively thermo stable compounds such as CN, CS, or CR is to formulate the active ingredient with a pyrotechnic base (i.e. chlorate and lactose). Pyrotechnic dissemination results in volatilization of the RCA, which condenses in cooler air producing a respirable aerosol. A description of the technology of the various devices for producing irritant smokes has been described by Swearengen (1966). Ballantyne (1977) in his review of RCAs discussed the mode of use and had categorized devices available for law enforcement and personal protection as powder formulation devices and liquid formulation in spray canisters. Powder formulation devices were used in the past and were associated with injury to the eyes – these devices are seldom used in present-day law enforcement operations and personal protection. Riot control agents CN, CS, and OC may also be dispersed as aerosols via pressurized containers consisting of the RCA in a carrier/solvent and propellant. Modern “aerosol can” technology has provided a safe and convenient method for the dissemination of RCAs present in liquid formulations. Macleod (1969) has provided a description of the differences between thermal and solvent spray devices. Ditter and Heal in Chapter 2 provide a historical overview of dissemination technologies developed for RCAs as well as an up-to-date account of contemporary dissemination technologies. Pyrotechnic devices have application in crowd control and in “peacekeeping” operations, whereas dispersion via pressurized containers have found use in law enforcement applications as well as for personal protection.

1.3

HISTORICAL PERSPECTIVES

Lacrimatory and irritant compounds, many of which are listed in Tables 1.3 and 1.4 have a history dating from the First World War. Many of these chemicals have been deployed as chemical warfare agents and others (e.g. CN, CS, DM) have been used in riot control and civil disturbances and in military exercises and training. Tear gases of the First World War included acrolein (papite), bromoacetone (BA, B-stoff), bromobenzyl cyanide (CA, BBC), chloroacetone (A-stoff), xylyl bromide (T-stoff), and diphenylaminochloroarsine (DM). Chloropicrin (trichloronitromethane), a well-known chemical prior to the First World War, was used both as a harassing agent and lethal war gas. In fact, chloropicrin was one of a number of lethal agents – the others being chlorine, phosgene, and trichlorethylchloroformate. The highly potent lacrimator, BA, was the most widely utilized lacrimatory agent in the First World War. Xylyl bromide, also known as T-stoff, was also employed. Another highly potent lacrimatory compound developed prior to the


RIOT CONTROL AGENTS

TABLE 1.3 Tear gases (lacrimatory compounds) Compound

Chemical name

Application Codea

Former

Current

Intermediate Experimental tear agent Experimental tear gas Experimental tear gas Tear gas

Intermediateb Reagent

Benzyl bromide Benzyl iodide

1-Bromotoluene 1-Iodotoluene

(—) (—)

Ethyl iodoacetate

Iodoacetic acid, ethyl ester

KSK

Iodoacetone

l-Iodo-2-propanone

(—)

Tropilidene

1-Methoxy-1,3,5-cycloheptatriene

CHT

Reagent Reagent Tear gas

Notes a Military code or identifier – usually one legitimate code designation. b Chemical intermediate for certain industrial chemicals.

TABLE 1.4 Tear agents utilized as war gas in the First World War Compound

Acrolein Adamsite Bromoacetone Chloroacetone Chloropicrin Green Cross I Xylyl bromide

Chemical name

2-Propenal 10-Chloro-5,10-dihydrophenarsazine 1-Bromo-2-propanone 1-Chloro-2-propanone Trichloronitromethane Phenylimidocarbonyl chloride -Bromoxylene

Application Codea

Former

Current

Papite DM

War gas War gas

Intermediateb Obsolete

BA A-stoff PS (#)c T-stoff

War War War War War

Reagent Intermediateb Fumigant Reagent Reagent

gas gas gas gas gas

Notes a Military code or identifier – usually one legitimate code designation. b Chemical intermediate for various industrial chemicals and pharmaceuticals. c (#) Military designation Green Cross I.

1920s was ethyl bromoacetate. Swearengen, referred to ethyl bromoacetate as the first RCA – based on its use in Paris in 1912 (Swearengen, 1966). Moreover, according to Royer and Gainet (1973), ethyl bromoacetate was purported to have been used in the 1970s in riot control situations. Vomiting agents, which are arsenic-based compounds, were also developed during the latter stages of the First World War and included: diphenylchlorarsine (DA), diphenylcyano-arsine (DC), and diphenylaminochloroarsine (DM, adamsite). These compounds in addition to causing emesis also produce severe irritation to the eyes, nose, and throat. The vomiting agent adamsite, also classified militarily as a sternutator, was utilized as an RCA after the war. Utilization of these compounds in closed and confined spaces resulted in rapidly attained incapacitating dosages and an elevated risk for fatalities.



The lacrimatory agent, CA, also known as camite, was a replacement for arsenical vomiting agents. CA and related compounds were early RCAs. These compounds were developed at the end of the First World War initially to supplement and subsequently to replace the vomiting agents. CA is a potent eye and respiratory irritant with an immediate onset of action. It is characterized as possessing appreciable toxicity. CA became obsolete in the 1920s with the introduction of CN. Although CN was discovered over a century ago, it was not used in the First World War. In the late 1920s, CN was utilized in French colonies to break up civil disorders, and was adopted worldwide for use by law enforcement agencies soon thereafter. For many years, CN was the most widely used RCA by civil and military authorities as well as for personal defense. In contemporary terminology, CN is referred to as “mace” (Mace®), a liquid mixture containing CN in kerosene hydrocarbons and 1,1,1-trichloroethane and Freon® propellant (i.e. 1,1,2-trichloro-1,2,2-trifluoroethane). Mace® is the brand name for a specific product containing CN and should not be used as a generic term for all defense spray products. CN was also formulated with various solvents (e.g. carbon tetrachloride, benzene) to yield a highly irritating mixture. The agent CNB (CN, carbon tetrachloride, benzene) was once used as a training agent. Another CN formulation (i.e. CNS – a mixture of CN, chloroform, chloropicrin) was developed not so much as a lacrimatory agent but as a non-arsenical vomiting agent. CN is still produced; however, it has limited application in present-day law enforcement and “peacekeeping” operations. The emergence of chemicals such as CN into law enforcement operations stemmed from military experience with harassing agents. However, many of the military “harassing agents” were not suitable for law enforcement use due to concerns associated with the likelihood of causing fatalities and/or total incapacitation. Consequently, the development of modern RCA has been driven by requirements to develop safe and effective compounds that could be easily disseminated. It is important to note that RCAs are intended to temporarily disable – the intense irritant effects producing a varying degree of incapacitation. An in-depth discussion on incapacitation is not intended since several sources, which provide detailed discussions on the “incapacitating” effects of RCAs, are available in the literature (e.g. Rothschild, 1964; Cookson and Nottingham, 1969; Rose and Smith, 1969; Jones, 1971). By the end of the First World War, a systematic search of compounds suitable for temporary incapacitation and riot control was in place. Despite a considerable amount of research endeavor on a substantial number of prospective compounds, interest soon focused on CN and DM. In later years, research efforts centered on the development of CS and dibenz[b,f]1:4-oxazepine (CR) as RCAs. Between the First and Second World War, CN and DM had become the harassing agents of choice despite the early use of CA as an RCA. There existed considerable stockpiles of CN and DM at the time of the Second World War. Although DM was employed as an RCA, CN superseded DM as an RCA. Despite the widespread use of CN, dissatisfaction with the potency and chemical stability of CN prompted research initiatives to develop alternative RCAs. CS, which manifested greater potency and lower toxicity, was the replacement for CN. Although CS was synthesized initially by Corson and Stoughton in the late l920s (Corson and Stoughton, 1928), it was not developed as an RCA until the 1950s. CS is a highly effective peripheral sensory irritant useful against both crowds and individuals – it is fast-acting and has a high safety ratio. There has been no report of death caused by CS despite its wide usage. CS was adopted as a standard RCA by the US Army in 1959, and National Guard Units have incorporated CS in their riot control inventory. CS is also commonly used as a training agent and for testing of respirators. CS is used as an RCA in many countries, and since its introduction CS has virtually replaced CN as the RCA of choice in the USA and England. CS is usually mixed with a pyrotechnic mixture in a grenade or canister for use. Its useful form is indented as a smoke or fog of suspended particles. Micronized formulations of


RIOT CONTROL AGENTS

CS, known as CS1 and CS2, have been developed and evaluated for toxicity (Weigand et al., 1969; NAS, 1984; NTP, 1990). The additives in CS1 and CS2 prevent agglomeration and produce a free-flowing powder that can be dispersed from powder formulation devices. Liquid formulations containing CS, as the active ingredient, have also been developed for use in personal defense sprays. More recent additions to the RCA inventory include CR, tropilidene, and OC (“pepper spray”). CR, characterized as having lower toxicity than either CN or CS, is an RCA of relatively recent origin – it has seen limited application. Increased use of CR in riot control situations is possible owing to the compound’s greater potency and lower toxicity than some of the other RCAs to include CS. The compound, 1-methoxy-1,3,5-cycloheptatriene (CHT, tropilidene), has been demonstrated to be a potent irritant with physiological effects characteristic of RCAs. In general, tropilidene toxicity is similar to that of CR. OC (“pepper spray”), an oily extract of hot peppers, is a highly variable and complex mixture of ingredients, with capsaicin as the major pungent component. OC has seen a marked increase in its utilization in law enforcement and riot control situations following the publication of an FBI study on the use of Cap-Stun®, an OC-based product. OC sprays for law enforcement and personal defense were first developed in the 1970s as an alternative to CN and CS sprays and have gained widespread acceptance by law enforcement agencies and the public. “Pepper spray” is available over-the-counter for personal protection and is also used by postal carriers for repelling animals and by campers as a bear repellant. A recently developed “incapacitant” spray for law enforcement use contains nonivamide (“synthetic capsaicin”) as the active component and is marketed under the brand name CapTor®.

1.4 HAND-HELD DEVICES AND PERSONAL PROTECTIVE SPRAYS Although commonly utilized as RCAs, lacrimatory compounds also constitute the active ingredient in defense sprays. These are hand-held devices for use in the field and in training exercises by law enforcement personnel and as commercial products for self-protection. These products are marketed as different types of devices under varying trade names (i.e. CapStun®, CapTor®, Freeze®, Guardian®, Punch II®, Sabre®, etc.). Pressurized dispensers of varying sizes and shapes have been available to law enforcement agencies and for overthe-counter sale since the 1960s. Typical spray canisters range from 0.3- to 10-ounce containers. These devices have the capability to dispel active ingredient(s) in the form of an aerosol for a distance of 3–18 meters. The maximum direct spray range of personal defense products is generally 2–5 meters. However, irritant effects can be produced up to 30 meters distant depending on a number of factors such as canister size, pressurization, amount of active ingredient, nozzle type, and ambient conditions (Lee et al., 1996). Protective spray devices are designed to incapacitate by producing intense lacrimation, acute eye irritation, and mild to moderate respiratory distress. Exposure to RCA(s) from self-defense sprays is usually of short duration, of low dosage, and is usually associated with mild symptoms. Most of the currently available personal defense sprays contain one of the following RCAs: CS, CN, and OC. The amount of active ingredient (s) among the different brands of defense/incapacitant sprays varies, depending on the specific RCA used, but typical concentrations range between 0.5% to 10% (i.e. CN and CS at concentrations of 1–6%, capsaicinoids in “pepper spray” from 1.2% to 12.6%). A standardized color-coding system has been established to aid in identifying the active ingredient in personal defense sprays. The color code is orange for OC, blue for CS, and red for CN. To increase their effectiveness or for marketing purposes, several personal defense sprays contain a combination of active



ingredients – most commonly CS or CN is combined with OC. A combination of CS and “pepper gas” is marketed under the trade name Sabre®. In addition to their active ingredient(s), defense sprays contain a carrier (solvent) in which the active component is solubilized or mixed and a propellant. Solvents used in current formulations or in previous RCA formulations include the following: water, isopropyl alcohol, methylene chloride (dichloromethane), methyl isobutyl ketone, propylene glycol, polyethylene glycol, and 1,1,1-trichloroethane (methylchloroform). There is no ideal solvent (either alcohol- or nonalcohol-based) as a carrier for the active ingredient that provides for optimal dissemination, component compatibility, and a favorable toxicological/safety profile. Among the available solvents, isopropyl alcohol (isopropanol), a widely used ingredient in many household aerosol devices, has several advantages over some of the other carriers (e.g., noncarcinogenic, nonmutagenic, non-ozone depleting). However, a major concern with isopropanol, as a carrier/solvent in defense spray formulations, is its high flammability. Trichloroethane (methylchloroform), a nonflammable, colorless liquid, was used as a carrier/solvent in defense sprays. Prior to the mid-1990s, methylchloroform was widely used as an industrial solvent and in a variety of consumer products. It was occasionally used as an aerosol propellant. Methylchloroform is relatively less toxic than most chlorinated solvents, which in part accounted for its extensive use prior to recognition of its ozone-depleting characteristic. The production of methylchloroform ended in 1996 in the United States as part of the phase-out of ozonedepleting chemicals – its use has declined. Another solvent/carrier used in defense spray formulations is methylene chloride, a solvent used in manufacturing and food technology. Methylene chloride is currently used as a solvent/carrier for CS-based defense sprays. It is considered nonflammable – NFPA hazard rating for flammability is zero. The use of methylene chloride in defense spray formulations is questionable due to its inherent toxicity, its potential to produce carcinogenic/mutagenic effects, developmental and reproductive effects, and skin reactions. There have been many initiatives to develop alternatives to these solvents; however, replacements for some of the currently utilized solvents are not immediately forthcoming. There are numerous devices for propelling and spraying the liquid contained within an aerosol container/dispenser. Virtually any propellant used for household products can be used as a propellant in defense spray formulations. Propellants used in past RCA formulations have included: chlorofluorocarbons (CFCs) (i.e. dichloro-, trichlorofluoromethanes), and propellant gases (i.e. liquefied gas (butane, isobutane, propane) and compressed gas (nitrogen, CO2) ). Most modern aerosols use a liquefied gas as the propellant. Butane, isobutane, and propane have replaced CFCs in homecare products, toiletries, disinfectants, room fresheners, etc. and are still used in defense spray formulations. Currently, most defense spray manufacturers use nitrogen gas as a propellant. A major drawback using nitrogen as a propellant is the reduction in the overall pressure, which results in a progressively weaker stream force/spray with a consequent decrease in product effectiveness. Some of the newer defense spray formulations utilize Dymel® as the propellant – a recently developed product for pharmaceutical application (i.e. nasal inhalers and oral sprays). Dymel® (1,1,1,2-tetrafluoroethane) is a non-ozone-depleting alternative propellant that provides several advantages over existing propellants (i.e. the original operating pressure of the canister is maintained, compatibility with active ingredient, nonflammable). Other recently developed propellant technologies are based on a combination of a simple hydrocarbon and carbon dioxide. A summary of various RCA formulations, that have been developed for defense sprays is given in Table 1.5. The relationship between formulations and dissemination methodologies is subsequently discussed. The implications for health and environmental effects are presented in subsequent chapters on the pharmacology/toxicology, reproductive, environmental, and public health aspects of RCAs.


RIOT CONTROL AGENTS

TABLE 1.5 Self-defense spray formulationsa Brand name

Riot control agent

Carrier/solvent

Propellant

Mace®

CN

Freon® 113

Paralyzer® (—)b (—)c

CS CS CR

CapStun® Punch II® Sabre 5.5® CapTor® Mace® Triple-ActionTM Sabre®

OC OC OC Nonivamidea CN/OC

Kerosene hydrocarbons, 1,1,1-trichloroethane Methylene chloride Methyl isobutyl ketone Propylene glycol, propylene glycol/water Isopropanol Isopropanol (—)d Water/ethanol (—)d

Isobutane/propane Isobutane Dymel® 134a/P (—)e (—)d

CS/OC

(—)d

Dymel® 134a/P

Nitrogen Nitrogen Nitrogen

Notes a Self-defense sprays are also referred to as “aerosol subject restraints” (ASRs). b Formulation used by English and French law enforcement agencies. c Not available as a commercial product. d Trade secret/proprietary. e Contents can be pressurized to varying degrees.

Personal defense sprays vary with respect to the type of spray pattern produced – these are mist, stream, and burst. Mist or “cone” nozzles produce a cone-shaped pattern of dissemination of agent, which is less concentrated than an aerosol cloud generated by a burst nozzle. A stream nozzle produces a thin stream of agent and the spray device must be aimed directly at the facial area of the intended target in order to be effective. A device having a burst-type nozzle, also referred to as a “fogger”, produces a dense, focused cloud of aerosolized agent. A fogger generates a high volume of agent in a relatively focused area, hence not requiring a precise aiming to be effective. The direct spray range of personal defense products is 2–5 meters; however, variations in irritant effects may occur, dependent on parameters such as nozzle type, pressurization, canister size, and ambient conditions. Manufacturers recommend minimum distances for use of these sprays, which is based on the distance required for the propellant and carrier to dissipate. Optimally, the individual is exposed to the active ingredient and to residual amounts of carrier and propellant.

1.5 ACTIVE INGREDIENTS OF DEFENSE SPRAYS Chloroacetophenone, a mixed aliphatic–aromatic ketone, has been used in personal defense products since the 1920s – this compound was known prior to the First World War. Among the first such products were tear gas pens and pistols that used a ballistic device to propel CN particulate at an attacker (Sanford, 1976; Beswick, 1983). CN was initially marketed as a personal defense spray in the mid 1960s under the brand name Mace®. This product acquired widespread use in the 1960s, and the term “Mace” is still generically used – although incorrectly – to describe all aerosol defense sprays. Defense spray devices produce CN concentrations that can result in extreme ocular



irritation, burning sensation, copious lacrimation, and blepharospasm; however, such devices usually do not produce levels of CN that result in more serious ocular injury (i.e. corneal edema, keratitis, and conjunctival injury). CN-induced respiratory tract injury is usually not associated with the use of personal defense sprays – the concentration of CN associated with respiratory injury is well beyond the levels that can be generated by typical personal defense sprays. Personal protective devices are also marketed with o-chlorobenzylidene malononitrile as the active ingredient. The extensive use of this RCA in such devices is the result of the following factors: (1) a greater degree of effectiveness and lower toxicity compared to CN, (2) dissatisfaction with the performance of CN, and (3) chemical instability of CN. Of further note is that CS is less likely than CN to cause ocular injury due in part that lower concentrations of CS are needed to achieve an equivalent response (Hu, 1992). Despite its high effectiveness when used in pyrotechnic devices, the utility of CS as a highly effective incapacitant in a defensive law enforcement hand-held device has been questioned and has come under increasing scrutiny. It is viewed by some that in hand-held devices, CS is too slow reacting as a true incapacitant, and that CS is associated with too many “secondary” effects. Apart from some operational characteristics, CS is generally considered safe and effective. Regarding decontamination and environmental concerns, CS is a relatively persistent material, and may pose problems related to personal and environmental decontamination and environmental remediation. OC and more recently “synthetic capsaicin” (nonivamide) in personal protective sprays are the more recent developments in defense sprays. OC is composed of naturally occurring compounds, not all of which contribute to effective pungency. OC has been incorporated into various formulations and marketed as “pepper spray”, “pepper gas”, and “pepper mace” for law enforcement, civil disturbance control purposes, criminal incapacitation, and self-defense. In present-day parlance, sprays containing OC are commonly referred to as “pepper” sprays. Personal defense sprays containing OC were first developed in the 1970s as an alternative to CS- and CN-based sprays. As a spray, OC rapidly produces lacrimation and involuntary closure of the eyes. It also elicits respiratoryrelated responses and burning sensation of the skin. Consequently, exposed individuals in most cases can be subdued easily. Since OC extracts are highly complex mixtures of natural compounds at variable concentrations, there is considerable variation in the overall chemical composition of OC-based formulations used in OC weaponry. As previously mentioned, the capsaicinoid content of extracts used in “pepper sprays” varies from 1.2% to 12.6%. Since the amount of OC extract used in “pepper sprays” also varies (5–15%), the potential effects associated with OC exposure may vary as much as 30-fold among different brands of OC spray. The Scoville Heat Unit (SHU) is often used to compare the relative potency (“pungency” or “heat” content) of OC/capsaicinoids. Based on the Scoville System pure capsaicin is rated at 15 million SHUs – the OC in defense sprays typically has a rating of about 1.5 million SHUs. Most sprays use food grade OC while some use pharmaceutical grade pure capsaicin in their formulations. Food grade OC is fairly low in capsaicin content and is rather difficult to dissolve and aerosolize. A “settling effect” may also occur with poorly formulated OC sprays resulting in spray bursts of irregular composition. In general, formulations based on pharmaceutical grade, pure extracted capsaicin are highly effective. Despite the marked variation in capsaicin/capsaicinoids content among the various OC formulations and the potential diminishing effective concentrations of OC formulations over time, OC sprays have gained widespread acceptance among the public and by law enforcement personnel. A National Institutes of Justice (NIJ) report identified sixteen manufactures of “pepper spray” in the USA (NIJ, 1994). Proponents of OC sprays contend that the use of OC in spray devices overcomes some of the problems encountered with CN and CS sprays and afford operational advantages over CS and CN devices. OC sprays are effective in


RIOT CONTROL AGENTS

producing instantaneous ocular effects and very rapid incapacitation of almost all subjects (NIJ, 1994). OC sprays are generally regarded as safe; however, there have been a number of deaths associated with OC use; however, a causal relationship has not been established. A defense spray under the trade name CapTor® is of very recent origin and contains “synthetic capsaicin” (nonivamide) – as the active ingredient. Nonivamide was first synthesized in 1919 (Nelson, 1919) and has been used in the spice and pharmaceutical industries. Nonivamide is commonly referred to as “synthetic capsaicin”; however, it is a natural component found in Capsicum species having been isolated and characterized (Constant and Cordell, 1996). Nonivamide has been evaluated for pungency along with other alkylvanillylamides and found to be as pungent as capsaicin. Its use in defense spray devices affords several advantages over OC-based formulations, most notably producing a desirable incapacitant effect without respiratory and skin complications, thus minimizing adverse effects. Moreover, defense spray formulations containing nonivamide can be manufactured to strict, repeatable, and quantifiable production standards which is not achievable with OC-containing formulations. Ditter and Heal, in Chapter 2, provide a detailed discussion pertaining to hand-held devices used by law enforcement personnel as well as self-defense spray products available for personal protection.

1.6 DEGRADATION AND DECONTAMINATION PRODUCTS In the past, not much attention was directed toward identifying degradation products formed during the pyrotechnic dispersion of RCAs and to the health and environmental aspects of RCA degradation products. The dissemination of RCAs by pyrotechnic means and the concerns regarding the decontamination of these chemicals are matters of growing concern to the public health and environmental communities. Thermal decomposition products are produced on pyrotechnic dispersion of RCAs, and their formation and identification have been only recently addressed (Kluchinsky et al., 2001, 2002; Smith et al., 2002). The studies by Kluchinsky and coworkers have focused on the formation of thermal degradation products of the riot control agent CS. Analytical methodologies to detect thermal breakdown products of RCAs have been developed with the goal of developing procedures for rapid on-site detection and identification. Regarding toxicological studies on RCAs, it can be said that the great majority of studies have focused on the RCA alone, various studies on RCA with carrier/solvent, and very few on formulations or degradation products. Studies have focused on characterizing the toxic effects of the individual RCA with minimal consideration regarding the potential contribution of breakdown products to the overall toxicity. For example, assessments of human exposure to CS have focused on CS alone and have not accounted for CS-derived thermal degradation products. The potential health and environmental risks posed by RCAs and their decontamination products are also of growing concern to environmental and public health officials. Riot control agents CN, CR, and CS are not readily degradable since they undergo hydrolysis to a very limited extent. Decontamination of these agents can be accomplished using alkali; however, depending on the situation, decontamination may be difficult under certain conditions. RCAs are biodegradable; however, degradation via biodegradation processes requires a considerable time period. OC is biodegradable and does not pose as great an environmental contamination problem. The environmental issues/concerns related to RCA use/application, environmental contamination, and remediation are discussed in detail in Chapter 16.



1.7 CLASSIFICATION Introductory remarks regarding RCAs is incomplete without a discussion pertaining to the issues regarding the classification of RCAs. RCAs have both civil and military applications and have been categorized as either chemical warfare agents or as military chemicals. Historically and to the present, the classification of military chemicals and chemical agents is based on a predominant physiologic action. However, classification may also be based on use, physical state, or persistency (Prentiss, 1937; Jacobs, 1942; Waitt, 1942; Sartori, 1943). Physiologically, RCAs may be classified as to type, namely, lacrimators, vomiting agents, and sternutators. Lacrimators primarily cause eye irritation and lacrimation, whereas vomiting agents additionally cause emesis. The predominant physiological actions of sternutators are sneezing and coughing. Moreover, RCAs have also been referred to as irritants or irritating agents (Sidel and Goldwyn, 1966; NAS, 1984), harassing agents (Robinson, 1968; Volmer, 1969; WHO, 1970; Hu, 1992), and incapacitating agents or short-term incapacitants (WHO, 1970; Hu, 1992; NRC, 1999). It is important to note, that the categories as identified represent general classifications or have special meaning in terms of military usage and may not represent useful equivalents. Thus, vomiting agents may be incorrectly described as RCAs. According to Cookson and Nottingham (1969), who have written an excellent overview of chemical warfare agents, vomiting agents should be considered as a distinct category of military chemicals. Further, it must be recognized that a physiologically based classification of chemical agents and compounds of military interest is by no means a rigid one. Thus, classifying a military compound, as a lung irritant; for example, does not mean it cannot be considered as a lacrimator. The classification issue may never be fully resolved, nevertheless a classification system serves to provide a basis for comparisons among chemical warfare agents and between chemical warfare agents and other chemicals. An excellent overview on the subject of classification; criteria to distinguish RCAs from chemical warfare agents; and concepts pertaining to “harassing”, “irritating”, and “incapacitating” is that of Verwey (1977). Further to the discussion on classification, a distinction is made between military chemicals and chemical warfare agents in the chemical warfare literature and in military Field and Technical Manuals. It should also be noted, that the term military chemical compound excludes chemical warfare agent. Military chemical compounds encompass the following categories: riot control agents (e.g. CN, CR, CS) ); training agents (e.g. CN); smoke materials (e.g. fog oil (SGF) and white phosphorus (WP) ); and herbicides (e.g. 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and arsenic trioxide). Some countries consider RCAs as chemical warfare agents while other countries do not consider RCAs as chemical weapons as historically defined (Sidell, 1997). Since the mid 1990s, the official United States policy on RCAs has been that these compounds are not chemical warfare agents (The Whitehouse, 1994). Despite considerable focus and much debate on the definition and classification of RCAs, recently published literature on the subject matter has not provided clear distinctions on the classification of RCAs and chemical warfare agents (Takafuji and Kok, 1997; NRC, 1999). RCAs should be viewed as peripherally acting chemicals that elicit reversible physiological effects. They are intended to temporarily disable – unlike chemical warfare agents such as the nerve gases, which are highly lethal substances.

REFERENCES BALLANTYNE, B. (1977) Riot control agents (biomedical health aspects of the use of chemicals in civil disturbances). In R.B. SCOTT and J. FRAZER (eds), Medical Annual, Bristol: Wright and Sons, pp. 7–41.


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BESWICK, F.W. (1983) Chemical agents used in riot control and warfare, Human Toxicology, 2: 247–256. COMPTON, J. (1987) Military Chemical and Biological Agents – Chemical and Biological Properties, Caldwell, NJ: The Telford Press. CONSTANT, H.L. and CORDELL, G.A. (1996) Nonivamide, a constituent of capsicum oleoresin, Journal of Natural Products, 59: 425–426. COOKSON, J. and NOTTINGHAM, J. (1969) A Survey of Chemical and Biological Warfare, New York: Monthly Review Press, pp. 183–191. CORSON, B.B. and STOUGHTON, R.W. (1928) Reactions of alpha, beta unsaturated dinitriles, Journal of the American Chemical Society, 50: 2835–2837. DANTO, B.L. (1987) Medical problems and criteria regarding the use of tear gas by police, The American Journal of Forensic Medicine and Pathology, 8: 317–322. DEANE-DRUMMOND, A. (1975) Riot Control, London: Royal United Services Institute for Defence Studies. HU, H. (1992) Toxicodynamics of riot control agents (lacrymators), in S.M. SOMANI (ed.), Chemical Warfare Agents, New York: Academic Press Inc, pp. 271–288. JACOBS, M.B. (1942) War Gases, their Identification and Decontamination, New York: Interscience Publishers Inc. JONES, G.R.N. (1971) CS in the balance, New Scientist and Science Journal, 50: 690–692. KLUCHINSKY, Jr., T.A., SAVAGE, P.B., SHEELY, M.V., THOMAS, R.J., and SMITH, P.A. (2001) Identification of CS-derived compounds formed during heat-dispersion of CS riot control agent, Journal of Microcolumn Separations, 13: 186–190. KLUCHINSKY, Jr., T.A., SHEELY, M.V., SAVAGE, P.B., and SMITH, P.A. (2002) Formation of 2-chlorobenzylidene malononitrile (CS riot control agent) thermal degradation products at elevated temperatures, Journal of Chromatography A, 952: 205–213. LEE, R.J., YOLTON, R.L., YOLTON, D.P., SCHNIDER, C., and JANIR, M.L. (1996) Personal defense sprays: effects and management of exposure, Journal of the American Optometric Association, 67: 548–560. MACLEOD, I.F. (1969) Chemical Mace® ocular effects in rabbits and monkeys, Journal of Forensic Sciences, 14: 34–47. NATIONAL ACADEMY OF SCIENCES (NAS) (1984) Possible Long-term Health Effects of Short-term Exposure to Chemical Agents, Vol. 2, Cholinesterase Reactivators, Psychochemicals, and Irritants and Vesicants, Washington, DC: National Academy Press. NATIONAL RESEARCH COUNCIL (NRC) (1999) Chemical and Biological Terrorism, Washington, DC: National Academy Press. NATIONAL TOXICOLOGY PROGRAM (NTP) (1990) NTP Report on the Toxicology and Carcinogenesis Studies of CS2 in F344/N Rats and B6C3F1 Mice (Inhalation Studies), NTP TR 377, March 1990, National Toxicology Program, Research Triangle Park, NC. NELSON, E.K. (1919) Vanillyl-acylamides, Journal of the American Chemical Society, 41: 2121–2130. NATIONAL INSTITUTE OF JUSTICE (NIJ) (1994) Oleoresin capsicum: pepper spray as a force alternative, Technology Assessment Program, March 1994, Washington, DC: Office of Justice Programs, US Department of Justice. PEARLMAN, A.L. (1969) Non-lethal weapons for use by law enforcement agencies, New Physician, August, 625–628. PRENTISS, A.M. (1937) Chemicals in War: A Treatise on Chemical Warfare, New York: McGraw-Hill Book Co. Inc. ROBINSON, J. (1968) Chemical weapons. In: S. Rose (ed.), Chemical and Biological Warfare. London: G. Harrap. ROSE, S. and SMITH, R. (1969) CS – a case for concern, The New Scientist, Sept: 468–469. ROTHSCHILD, J.H. (1964) Tommorrow’s Weapons, McGraw-Hill Book Co.: New York. ROYER, J. and GAINET, F. (1973) Ocular effects of ethyl bromoacetate tear gas, Bulletin of the Society of Ophthalmology (France), 73: 1165–1169.



SANFORD, J.P. (1976) Medical aspects of riot control (harassing) agents, Annual Review of Medicine, 27: 412–429. SARTORI, M. (1943) The War Gases, New York: D. Van Nostrand. SIDEL, V.W. and GOLDWYN, P.M. (1966) Chemical and biological weapons: a primer, New England Journal of Medicine, 274: 21–27. SIDELL, F.R. (1997) Riot control agents. In: Textbook of Military Medicine, Medical Aspects of Chemical and Biological Warfare, Washington, DC: Office of the Surgeon General, US Army, TMM Publications, Borden Institute, pp. 307–324. SMITH, P.A., KLUCHINSKY, Jr., T.A., ERICKSON, R.P., LEE, A.P., WILLIAMS, K., STEVENS, M., and THOMAS, R.J. (2002) Traditional sampling with laboratory analysis and solid phase microextraction sampling with field gas chromatography/mass spectrometry by military industrial hygienists, American Industrial Hygiene Association Journal, 63: 284–292. SUZUKI, T. and IWAI, K. (1984) Constituents of red pepper species: chemistry, biochemistry, pharmacology, and food science of the pungent principal of capsicum species. in A. Brossi (ed.), The Alkaloids, vol. 23, Orlando, FL: Academic Press, pp. 228–299. SWEARENGEN, T.F. (1966) Tear Gas Munitions, Springfield, Ill: Charles C. Thomas. TAKAFUJI, E.T. and KOK, A.B. (1997) The chemical warfare threat and the military health care provider, in Textbook of Military Medicine, Medical Aspects of Chemical and Biological Warfare, Washington DC: Office of the Surgeon General, US Army, TMM Publications, pp. 111–128. THE WHITEHOUSE, OFFICE OF THE PRESS SECRETARY (1994) Subject: Riot control agents, Press Release Dated June 23, 1994, The White House: Washington, DC. US ARMY CENTER FOR HEALTH PROMOTION AND PREVENTIVE MEDICINE (CHPPM) (undated), Detailed and General Facts about Chemical Agents – TG 218, CHPPM, Aberdeen Proving Ground, MD. VERWEY, W.D. (1977) Riot Control Agents and Herbicides in War, Leyden: A.W. Sijthoff. VOLMER, K. (1969) La querre chimique, Genie, 10: 21–24. WAITT, A.H. (1942) Gas Warfare, New York: Duell, Sloan, and Pearce. WEIGAND, D.A., MERSHON, M.M., and COX, A.T. (1969) The cutaneous irritant reaction to agent CS1. Reaction to certain solutions and slurries of CS1 at moderate and high environmental temperatures in human subjects, EATR 4380, Medical Research Laboratory, Edgewood Arsenal, MD. WORLD HEALTH ORGANIZATION (WHO) (1970) Health Aspects of Chemical and Biological Weapons, Geneva: World Health Organization.

DISCLAIMER NOTICE The use of either trade or manufacturer’s names in this work does not constitute an official endorsement of any commercial products. The contents of this chapter do not reflect the position or policy of any government agency. Responsibility resides solely with the authors.


CHAPTER

Application and Use of Riot Control Agents

2

JEANNE M. DITTER1 AND CHARLES S. HEAL2 1 US Army, Aberdeen Test Center, Aberdeen Proving Ground, MD 21005 2

Los Angeles County Sheriff’s Department, Los Angeles, CA 90022

2.1 INTRODUCTION Since the last decade of the nineteenth century when Germany and France began developing lacrimators for wartime use, (Smart, 1997: 11) and through the subsequent years of research and development of a variety of lacrimators/Riot Control Agents (RCAs) to the present day, the military has devised many different systems to dispense them. As law enforcement agencies began to adopt RCAs for riot control, and later on as part of their nonlethal capabilities, dispensing systems underwent further development in the last quarter of the twentieth century. During that same period, RCAs became available to individual citizens for personal protection and a variety of smaller dispensers were developed. Today the military is involved in an increasing number of peacekeeping missions and industry is developing new dispensing systems to fill the need for nonlethal capabilities as well as force protection requirements at their bases of operation. Use of RCAs has also evolved over the last century as side effects became known, environmental clean-up became an issue, and treaties and multinational agreements were signed.

2.2 DISPENSING SYSTEMS 2.2.1 Storage cylinders During the First World War, military usage of tear gas was conducted in conjunction with the use of chlorine gas and phosgene. Mortars and artillery were used to deliver RCAs initially, but due to a shortage of artillery shells, Germany began dispensing chlorine gas directly from its storage container into the trench system. Developed by the Germans for offensive chemical attacks, gas cylinders typically held 13–18 kg of agent. Gas was released directly from the cylinder via a valve and the wind dispersed it, hopefully in the right direction. The British took this cylinder system one step further with the development of the Livens projector. They used 8 inch (203 mm) tubes, dug several of them into the ground, loaded a propelling charge and gas cylinder into the tube, and then electrically fired off the cylinders in series. These cylinders held 13 kg of agent and had a range of 1,500 m. The biggest drawbacks of the Livens projector were its lengthy preparation or emplacement time, and the fact that once it was set up, it could not be moved and could only be fired once a day.


RIOT CONTROL AGENTS

2.2.2 Mortars The British, looking to improve on the Livens projector, used the 4 inch (102 mm) Stokes mortar to fire a smaller cylinder. The big advantage of the Stokes was its portability and ease of emplacement. The drawbacks to the system were its shorter range (1,100 m) and small gas cylinder which only held 3–4 kg of agent. In 1924, the barrel of the Stokes mortar was enlarged to 4.2 inches (106 mm) and rifled. The rifling imparted a spin to the projectile as it exited the barrel, thus stabilizing its flight trajectory and extending its range from 1,100 to 2,200 m. Today’s mortar cartridge can now reach a range of about 5,600 m. It consists of four canisters filled with a total of 0.7 kg of a pyrotechnic chlorobenzylidene malononitrile (CS) mix in either liquid or powder form. The canisters eject upon projectile impact on the ground or at a specified height above the ground.

2.2.3 Artillery projectiles Artillery consists of a cannon tube mounted on a carriage. Horses drew the carriages initially, but eventually were replaced by trucks when the armies became mechanized. Cannon sizes ranged from 75 mm through 105 mm and 155 mm, and even up to 10 inch (254 mm) during the First World War. Artillery shells could be fired to a range of 8–16 km with the largest shell carrying as much as 22 kg of agent. Today, towed artillery carriages still exist, but some artillery cannon systems are mounted on a wheeled or tracked self-propelled chassis. A 105 mm base-ejecting projectile carries a total of 0.6 kg of a pyrotechnic CS mix in four canister with a range of about 17 km.

2.2.4 Grenades Grenade bodies can be either a metal cylinder or a rubber sphere. There are two types of RCA grenades in use. One is a burning type grenade which has an igniting fuse that initiates after a delay of 1–5 s. The fuse ignites the filler and pressure builds inside the grenade body sufficient to open the gas ports and expel the pyrotechnic CS mix. Burning type grenades carry a payload mix of 270–410 g, of which 116–120 g is actually pelletized CS. Burning type grenades are hand thrown or propelled by a launcher to the upwind side of the target and allow the wind to disperse the CS or (CN) in a cloud of approximately 5 by 15 m. The greatest drawback to the burning type grenades is that they can cause nearby flammable materials to ignite. The bursting grenade is fused with a 1–2 second delay fuse containing low explosive detonator which ruptures the grenade body allowing the CS filler to disperse. These types of grenades are typically tossed or launched into the air such that they explode in the air several feet above the target. The CS cloud then spreads over an area of 10 by 25 m. As windspeed increases the gas cloud becomes longer and narrower. Non-pyrotechnic grenades also exist today that carry oleoresin capsicum (OC) or OC/CS mix payloads.

2.2.5 Cartridges Cartridges can be fired from a shotgun, a rifle-mounted launcher, or a specialized gas/air gun. Cartridges are probably the most widely used dispensing system in use by both the military and law-enforcement agencies today. They allow for greater distance and

18


APPLICATION AND USE OF RCA

accuracy on target than hand-thrown grenades. However, many have high-velocity projectiles which work well for penetrating wood and glass barriers, but can cause serious injury and death if fired at close range in a riot situation or during a training exercise. The 12-gauge shotgun cartridges consist of a plastic projectile filled with CS, CN, or OC in the liquid, or powder form. Rifle-mounted grenade launchers fire a 37–40 mm plastic or rubber projectile. Depending on the manufacturer’s design, the CS can be in liquid form or part of a pyrotechnic mix. They are accurate for a point target up to 200 m, and up to 400 m for an area target. Cartridges also exist with CN in a pyrotechnic mix or OC in a non-pyrotechnic powder. Another design which mounts on the muzzle of a rifle is the ring airfoil grenade. A blank cartridge is fired which supplies propellant gases to the launcher. The projectile forms into a 64 mm soft rubber ring with a spin rate of almost 5,000 rpm. This spin stabilizes the ring’s trajectory and makes it accurate. The ring comes in two versions. It can be used alone as a kinetic energy projectile or it can be embedded with CS or OC powder. The RCA disperses as a cloud upon impacting the target. Manufacturers have developed several specialized gas- or compressed air-operated guns. Some are designed specifically for use with standard 37–40 mm RCA cartridges and other nonlethal payloads, while others offer special caliber guns for use with its own unique munitions. As with the shotgun and rifle-launched cartridges, payloads can be non-pyrotechnic OC or CS/CN mix in liquid form and OC powder, or pyrotechnic CN or CS mixes.

2.2.6 Aircraft- or vehicle-mounted dispensers Aircraft were used to dispense CN and CS in several wars. Delivery methods varied from agent tanks mounted to the airframe to hand-dropped grenades. Aircraft-mounted systems usually consist of a large compressed air tank, two smaller agent tanks, hose and nozzle assemblies. This type of system can dispense 3.6 kg of CS in one continuous 19 second burst or in several short bursts for 30 seconds. Its optimal coverage area is 2,300–3,800 m2. A similar system can be mounted on a helicopter. However, since the agent is dispensed while the helicopter is hovering or moving along a line above or windward of the target, the risk of the rotor wash contaminating the helicopter is quite high, and the pilot and copilot must wear protective masks. Vehicle-mounted dispensing systems consist of a compressed air tank, two agent tanks, and hose and nozzle assemblies mounted on a truck bed. The RCA is dispensed ahead of the target or formation. Another version of this system, considered for use where the risk of abduction/kidnapping or other violent actions is high, can be mounted in the trunk of the car with RCA being dispensed from two nozzles located on each rocker panel. An agent cloud can be developed out to 6 m around the car. However, air for the occupants would need to be drawn through an additional filter system to prevent the occupants from being overcome by the agent.

2.2.7 Man-portable dispenser Man-portable systems have been around in basically the same form for the last 50 years. Like the aircraft and vehicle systems, it consists of a compressed air tank, one or two agent tanks, a hose, and a spray nozzle. Some systems dispense CR or CS solutions while others only dispense CS powder. Depending on whether the system uses solution or powder, its weight when full can run from 23 to 27 kg. Either agent type will project out to 12 m.

19


RIOT CONTROL AGENTS

2.2.8 Personal protection dispensers Using RCAs for personal protection or defense gained widespread use in the 1980s and 1990s. Both the military and law enforcement now carry aerosol dispensers ranging in size from 1.5 to 2.25 inches in diameter and 5.75 to 6.75 inches tall. Purse size dispensers range from 0.75 to 1.0 inch in diameter and 3–4 inches tall. Some are actuated by pressing down on a button on the top of the dispenser while others have a trigger type lever on the front which must be squeezed to start dispensing. Formulations can be CN, CS, CN/OC, CS/OC, and OC with OC available in 5- or 10-percent strength formulations. Depending on the dispenser, the aerosols can be disbursed as a stream, a foam, or a mist/fog. Streams and foams minimize cross-contamination, that is, individual targets, and their primary physical effect is on vision. Mists and fogs are designed to spread over a wide area and their primary physical effect is on the respiratory system. Generally, the effective range of most personal defense sprays is 2–5 m, although under favorable circumstances some physical effects can be produced out to 30 m.

2.3 USE OF RCAs The first use of CN was in the First World War along with smoke, chlorine gas, and phosgene as offensive weapons. Protective masks were not always effective, and soldiers were poorly trained in their use, such that many failed to get their masks on quickly enough or correctly. Some were too unnerved and undisciplined to obey an officer’s orders to don masks that they turned and ran, and subsequently died from exposure to chorine or phosgene (Smart, 1997: 18). Since soldiers could not initially differentiate whether the CN was being delivered alone or in combination with the more dreaded chorine or phosgene, the appearance of a gas cloud in the trenches had a powerful demoralizing effect. The US Army’s Chemical Corps used RCAs to subdue rioting by prisoners of war during the Korean conflict. Although CS produces similar effects to CN, it is less likely to cause serious injuries and toxic effects on the target. Its greater effectiveness at reduced concentrations led to CS overtaking CN in military usage. The British used CS as an RCA during the Cyprus riots and in riots and crowd control situations in Northern Ireland. The US Army officially adopted CS as an RCA for use in riots in 1960 (Logman, 1993: 16). The US Army used large amounts of CS in Vietnam to drive the enemy from deep caves, tunnels, and bunkers (Lewer and Schofield, 1997: 64). Persistent CS can deny the contaminated area to the enemy for weeks. However, once a cloud of tactical (nonpersistent) CS dissipates, no residual remains and the area is free for use again. There are drawbacks to CS. It is ineffective against dogs and most animals, some people under the influence of drugs or alcohol, and it has a relatively slow reaction time. CS can also be difficult to decontaminate. Although OC was first introduced to law enforcement in 1976, it wasn’t until 1989 that the FBI approved its use by their agents. Since that time, OC usage has become widespread in law enforcement agencies across the country and more slowly in the military services due to its greater effectiveness on aggressive people under the influence of drugs and alcohol, its almost immediate onset of intense physical effects, and its biodegradability (TAPIC, 1994; Lee et al., 1996; Busker and Van Helden, 1998).

2.3.1 Military use and application The US military services can employ RCAs only after the appropriate authority has approved its use or the rules of engagement have been established. They can be used for



ambush relief/withdrawal operations, riot control, rescue missions, convoy protection, nuclear weapons security operations, military operations in urban terrain (MOUT), base/perimeter defense, and terrain restriction (FM3-11, 1996: Ch. 7). For ambush relief/withdrawal operations, vehicle-mounted launchers would dispense RCAs to dissuade the attackers, or shield/mask unit movements. In a riot situation, the main objective is to control or maneuver the crowd into the desired outcome. This can be done by dispersing, grouping, moving, or channelizing the crowd. The reason for dispersing a crowd is to break it up into smaller, disorganized groups that are less likely to act in a hostile manner. This can be done by lobbing RCA grenades into the center of the crowd, or by using RCA grenades against the crowd on all sides at coordinated staggered time intervals. There are times when one may want to group the crowd into a small area such as to restrict the area affected by rioting and to allow one to focus your resources into a smaller area. Escape routes are blocked off until the area is contained. A variation on this maneuver is blocking off all escape routes but the one that you want them to take in order to move the crowd out of the area you need to occupy. This is done by using vehicle-mounted, man-portable, or cartridge RCA to attack the crowd from the opposite side you want them to go and blocking certain escape routes. The same method and RCA resources can be used to channelize the crowd into an area you have chosen. Since it also involves pushing the crowd from behind with the use of advancing forces as well as RCA, it is resource intensive and may not be a viable option with limited manpower and logistics. The US Army defines a rescue mission as the tactical rescue of an encircled military force by another force that has freedom of movement (FM3-11, 1996: 7-2). RCAs can be used at the breakout point to confuse or disburse the attackers in order to create a hole in the enemy’s lines, or to support the delaying action of the rear guard once the encircled force has been successfully extracted. Dispensing systems used to achieve either action could include cartridges, grenades, vehicle-mounted, and man-portable systems. In convoy protection, RCAs are used to break contact with the attackers and clear a path out of the area. Soldiers within the convoy don protective masks as soon as the attack commences. Vehicle-mounted RCA as well as grenade RCA are deployed to fend off the attackers, and would continue to be deployed ahead of the column along the intended path. In the protection and recovery of nuclear weapons, the rules of engagement authorize the use of RCAs and may well include deadly force. The rules will have clearly defined levels of force with the use of RCA as the last step before engaging in lethal force, and once it is decided to engage lethal force, RCA use must cease. Dispensing systems would include cartridges, launchers, grenades, vehicle-mounted, and man-portable systems. In MOUT situations, the use of conventional weapons can cause significant property damage and civilian casualties; an undesirable outcome for a military commander both for political and military reasons. RCA dispensed from vehicle-mounted, man-portable, grenades, or launching systems can be used to clear the enemy from basements, subterranean tunnels, sewers, and buildings. Mortars and artillery can deliver RCA in combination with smoke to suppress enemy rocket and mortar fire. In today’s heightened state of alert due to the increased threat of terrorism, base/ perimeter defense and force protection have taken on greater importance. RCA and other nonlethal capabilities have become an integral part of the base’s defense plan. Dispensing systems include vehicle-mounted, man-portable, grenades, cartridges, and launchers. Terrain restriction involves contaminating areas used by the enemy in order to reduce or hinder use of, or access to, lines of supply and communication, and operational areas. Persistent CS applied in bulk by aircraft or with artillery and mortar fire forces the enemy to find alternate routes or to attempt to clean up the area; either option causes the enemy to commit time and resources at considerable cost.


RIOT CONTROL AGENTS

2.3.2 Law enforcement use and application For law enforcement agencies, the most common situations that would call for the application of RCAs are crowd control/riots, barricade situations, and close proximity encounters (Sweetman, 1987: 11). During the 1960s and 1970s, the police faced frequent demonstrations and riots. The last two decades of the twentieth century saw a significant decline in occurrences, but since the turn of the century demonstrations have become more frequent.

2.3.3 Crowd/riot control Jones (2000: 52) stated that more than one type of crowd or mob may be present in any assemblage and law enforcement must be able to distinguish these elements in order to accurately respond with the minimum amount of force necessary to maintain control. He defined a crowd as a large number of individuals temporarily congregated in a limited area. A mob he defined as a crowd whose members, due to intense excitement or agitation, lose their sense of reason and respect for the law, and subsequently engage in unlawful, disruptive, destructive, and violent acts. Jones also stated that crowds and mobs have different characteristics. A crowd is ruled by reason, maintains respect for the law, and is usually unorganized. A mob, on the other hand, is ruled by emotion, loses respect for the law, and has a leader or instigator who has brought the group together under a common cause or motive for action. Jones further divided crowds and mobs into types. A casual crowd is not organized and is without a psychological unity, while a psychological crowd shares a sustained common intent and responds emotionally to the same stimulus. An aggressive mob has only one intent and their actions are all aimed at the destruction of people and property. An escape mob is made up of frightened individuals whose sole intent is to secure safety by flight without regard to the safety of others around them, such as in a fire. An acquisitive mob is motivated solely by the desire to acquire something, such as an uncontrolled looting space. Law enforcement is aimed primarily at keeping a crowd from attacking officers or other persons in an attempt to provoke police response and subsequently degenerating into a riot. Law enforcement has the same ways of controlling crowds as the military, that is, dispersing, grouping, moving, or channelizing. RCA grenades, gas guns, and cartridges are most frequently deployed, but vehicle-mounted and man-portable systems can be used, if available, and sufficient time exists to plan their most effective use. Consideration must be given to crowd type and intent, the desired effect, terrain or situational awareness, weather, and RCA availability. RCAs should not be thrown directly at rioters; instead, they should be released about 3–4 m in front of the police line and 25 m in front of the rioters (Jones, 2000: 54). Law enforcement agencies typically have the same or similar RCA munitions to those used by the military at their disposal and frequently have access to new innovative technologies before the military services. The OC aerosols were in use by many law enforcement agencies before the military services accepted it into their inventories.

2.3.4 Barricade situations This situation occurs when one or more persons take refuge or barricade themselves in a building. This can include a person who threatens to harm himself and/or innocent hostages or bystanders if certain demands are not met. When negotiations fail, CS is typically the RCA used to disorient and/or dislodge the target. RCA dispensers used for



this situation include grenade launchers, gas gun cartridge launchers, and shotgun cartridges. Expulsion projectiles with impact fusing are the preferred munitions since pyrotechnic rounds can cause inflammable materials with the building or room to catch fire or penetrate the walls of the target room. Pyrotechnic rounds launched by law enforcement were alleged to have started the fires within the Branch Davidian complex in Waco, TX, with the resultant conflagration taking the lives of all within.

2.3.5 Close proximity encounters A close proximity encounter involves individuals such as violent criminals, those under the influence of drugs or alcohol, mentally disturbed persons, and those under custodial supervision, who pose a serious danger to officers and others (Sweetman, 1987: 11). In these situations, immediate compliance or incapacitation is the desired effect. Law enforcement agencies, as well as private citizens, use OC personal defense aerosols more often than CS or CN aerosols because its inflammatory effects are more immediate and effective against aggressive or intoxicated attackers than the irritant effects of CS. OC’s lack of lingering effects and ease of clean up are added bonuses. The aerosols are applied in short bursts rather than a constant stream. This allows the officer/citizen to correct their aim as the attacker moves and minimizes exhausting the OC aerosol before compliance or incapacitation is achieved. Other RCA dispensers would seldom, if ever, be used in this type of situation because their size would be awkward to carry and their risk of serious injury or even death is too high. RCAs have undergone extensive research and development over many decades. The methods of delivering these RCAs have undergone parallel development. It is an area that will continue to evolve as the world searches for more effective, faster acting, less toxic agents. Application and use of RCAs will also evolve to take advantage of new innovations. However, whether used by the military, law enforcement agencies, or private citizens, the only way to ensure the most effective application of RCA is to (1) understand the different RCA munitions and their dispensers, types, and performance effects; (2) develop a deliberate and thorough deployment plan; and (3) conduct thorough training in their use.

REFERENCES BUSKER, R.W. and VAN HELDEN, H.P.M. (1998) Toxicologic evaluation of pepper spray as a possible weapon for the Dutch police, American Journal of Forensic Medicine and Pathology, 19(4): 309–316. FM3-11 Flame, Riot Control Agent, and Herbicide Operations (1996) Field Manual 3-11, Fort McClellan, AL: US Army Chemical School, 19 August. FM19-15 Civil Disturbances (1985) Field Manual 19–15, Washington, DC: Headquarters, Department of the Army, 25 November. JONES, T. (2000) Crowd control: the chemical agent option, Police & Security News, 16(3): 52–57. LEE, R.J., YOLTON, R.L. YOLTON, D.P., SCHNEIDER, C., and JANIN, M.L. (1996) Personal defense sprays: effects and management of exposure, Journal of the American Optometric Association, 67: 548–560. LEWER, N. and SCHOFIELD, S. (1997) Non-Lethal Weapons: A Fatal Attraction?, London: Zed Books Ltd. LOGMAN, C. (1993) Cap-Stun Weapon Systems Aerosol Product Line Law-Enforcement and Military Technical Information, Zarc International, Inc. SMART, J. K. (1997) History of chemical and biological warfare: an American perspective, In F., R. SIDELL, E. T. TAKAFUJI, and D. R. FRANZ (eds) Medical Aspects of Chemical and Biological Warfare, Chapter two, Washington, DC: Borden Institute, Walter Reed Army Medical Center.


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SWEETMAN, S. (1987) Report on the Attorney General’s Conference on Less Than Lethal Weapons, Washington, DC: US Department of Justice/National Institute of Justice, Office of Communication and Research Utilization, March. Technology Assessment Program Information Center (TAPIC) (1994) Oleoresin Capsicum: Pepper Spray as a Force Alternative, Washington, DC: National Institute of Justice/Technology Assessment Program, March.

DISCLAIMER NOTICE The contents of this chapter do not reflect the position, policy or practice of any Government agency. Responsibility for the contents of this chapter resides solely with the authors.


CHAPTER

Synthesis and Chemical Analysis of Riot Control Agents

3

SIDNEY A. KATZ1 AND HARRY SALEM 2 1

Rutgers University at Camden, Camden, NJ 08102-1411

2

US Army SBCCOM, Aberdeen Proving Ground, MD 21010-5424

3.1

INTRODUCTION

Many materials have been developed for use as nonlethal aerosols in personal defense, criminal incapacitation and crowd control. Exposure to these materials causes temporary irritation to the eyes, to the nose and throat, and to the skin. Excessive tearing and blinking, coughing and shortness of breath sometimes accompanied by retching and vomiting, and stinging and burning sensations on the skin bring about temporary disability. Some general characteristics of these materials are rapid onset of effects, brief duration of effects upon removal from the scene of exposure, and a wide safety range between exposure dose for incapacitation and exposure dose for toxicity. The toxicology of riot control agents (RCAs) has been the subject of numerous scientific studies and the focus of various review articles and book chapters (Ballantyne, 1977; Hu, 1992; Sidell, 1997; Olajos and Salem, 2001; Salem et al., 2001). Some of the materials used as active ingredients in the formulations of defense sprays utilized for law enforcement and personal protection include 2-chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS), dibenz[b,f]1:4-oxazepine (CR), oleoresin capsicum (OC), and nonivamide. Defense sprays containing a combination of RCAs have also been developed. The riot control agents CN and CS have been formulated with a pyrotechnic mixture for use in thermal or grenade devices. The military designations for the first three compounds mentioned above are CN, CS, and CR, respectively. By analogy, the fourth is often referred to as OC. Properties of the materials currently used as RCAs are listed in Table 3.1. Earlier formulations of RCAs were based on acrolein, benzyl bromide, bromoacetone (BA), bromobenzyl cyanide (CA), chloroacetone, chloropicrin (PS), ethyl bromoacetate, ethyl iodoacetate (SK), and xylyl bromide. These compounds were discarded long ago as viable RCAs due to their high toxicity and moderate potency in producing lacrimation and other “harassing effects.” Riot control CS has largely replaced CN, and CR has not been widely adopted. Current RCA formulations predominantly utilize CS or OC – several formulations incorporate more than one RCA. In addition to formulations containing lacrimatory substances as active ingredients, sternutators have also found application as RCAs; however, these compounds are likewise obsolete as RCAs. Among the chemicals that have been used for this purpose were diphenylchlorarsine, diphenylcyanarsine, and diphenylaminochlorarsine. Their military


RIOT CONTROL AGENTS

TABLE 3.1 Properties of lacrimators currently used as RCAs Property

Lacrimator

Molecular formula Molecular mass, dalton Melting point, C Boiling point, C Vapor pressure (20 C), torr

CN

CS

CR

OC

C8H7OCl 154.6 58–59 244–245 5.4 103

C10H5N2Cl 188.6 95–96 310 –315 3.4 105

C13H9ON 195.1 71–72 335 5.9 105

Mixture Variable Variable Variable

designations are DA, DC and DM, respectively. Like the lachrymators and peripheral sensory irritants, the sternutators cause temporary irritation to the nose and throat and have some effect on the eyes. The sternutators are also best known for producing violent uncontrollable sneezing, coughing, and vomiting. These compounds have also been described as vomiting agents owing to their marked ability to induce nausea and vomiting. The original military usefulness of agent DA, agent DC, and agent DM resided in their abilities to penetrate early gas masks and induce vomiting. Soldiers removing the vomitfilled masks were exposed to more toxic agents co-dispersed with the sternutators. DA, DC, and DM were deemed too toxic at field concentrations for use as RCAs in nonmilitary/law enforcement situations.

3.2 LACRIMATORS Lacrimatory compounds that have found use as RCAs are presented in Table 3.2 (also refer to Tables 1.1, 1.3, and 1.4 of Chapter 1). Discussion follows pertaining to the synthesis and analysis of lacrimatory compounds, currently utilized as modern RCAs, and the older lacrimatory agents.

3.2.1

Modern RCAs

Chloroacetophenone (CN) Chloroacetophenone, ACS Registry Number 532-27-4, with the chemical name 2-chloro1-phenylethanone, is also referred to as -chloroacetophenone, -chloroacetophenone, phenacylchloride, phenyl chloromethyl ketone, and in common parlance “MACE.” Chloroacetophenone has the military designation CN. Riot control agent CN was the tear gas of choice for the three decades following its introduction toward the latter stages of the First World War. With the development of chlorobenzylidene malononitrile in the mid-twentieth century, the use of CN declined markedly (CHPPM, 1996). Synthesis CN has been synthesized by passing a stream of chlorine into boiling acetophenone ( Jackson and Jackson, 1935). Subsequent syntheses described by Schaefer and Sonnenberg (1963) gave a 54% yield of CN by redistillation of the volatile products from the reaction between 2 g of acetophenone dissolved in 100 mL of benzene and 16.6 g of selenium oxychloride.


SYNTHESIS AND CHEMICAL ANALYSIS OF RCA

TABLE 3.2 Compounds used as lacrimators or as RCAs Lacrimatory compounds Designation

CAS no.

Chemical names

BA CA PS SK CN CR CS OC

598-31-2 5798-79-4 76-06-2

1-Bromo-2-propanone, bromoacetone Bromophenylacetylnitrile, bromobenzylcyanide Trichloronitromethane, chloropicrin Ethyl iodoacetate 2-Chloro-1-phenylethanone, -chloroacetophenone Dibenz[b,f]1:4-oxazepine [(2-Chlorophenyl)methylene]propanedinitrile Capsaicin Dihydrocapsaicin Norhydrocapsaicin Homocapsaicin Homodihydrocapsaicin

532-27-4 257-07-8 2698-41-1 404-86-4 19408-84-5 28789-35-7 58493-48-4 279-0605

CN is a white solid with a molecular mass of 154.6 dalton corresponding to a molecular formula of C8H7OCl. Molar solubility in water at 20 C is 4.4 103 mols/L ( 68 mg/100 mL). Melting and boiling points are 58–59 C and 244–245 C, respectively. Density of the solid is 1.318 g/cm3 at 0 C, and the density of the liquid is 1.187 g/cm3 at 58 C. The vapor is 5.3 times heavier than air. The vapor pressure of the solid is 2.6 103 torr at 0 C, 5.4 103 torr at 20 C, and 15.2 103 torr at 50 C. Analysis Zerba and Ruveda (1972) have described a gas chromatographic method for the identification and quantification of 2-chloroacetophenone, o-chlorobenzalmalonylnitrile, benzyl bromide, xylyl bromide, and diphenylaminechloroarsine as well as the impurities diphenylamine and bromotoluene. Using a Pyrex column packed with 3% OV-17 on Varaport 30 and a 12 C/min temperature program, they obtained base line resolution for a six component mixture of bromotoluene, benzyl bromide, xylyl bromide, -chloroacetophenone, o-chlorobenzalmalonylnitrile, and diphenlyamine. Response from the flame ionization detector was linear from 1 to 10 g. Diphenylaminechloroarsine was not detected under the conditions used for the six component mixture. Diphenylamine impurity or perhaps decomposition product was identified in the chromatogram. Isothermal gas chromatography was used by Jane and Wheals (1972). They reported retention times for -chloroacetophenone and o-chlorobenzalmalonylnitrile of 7.5 and 26 min, respectively, using a packed column of 2% carbowax 20M on Chromosorb G at 180 C. 2-chloroacetophenone, o-chlorobenzalmalonylnitrile and dibenz[b,f ]1:4-oxazepine were among the 22 chemicals of military interest and simulants for which D’Agostino and Provost (1985) determined gas chromatographic retention indices relative to the n-alkanes. In the course of this work, they developed a procedure for soil analysis in which agent was extracted from a 300 mg soil sample by ultrasonic vibration for 30 min with 1 mL of chloroform in a PTFE-lined, screw capped vial. A decade later, D’Agostino and Provost (1995) obtained spectra from the molecular ions and principle electron


RIOT CONTROL AGENTS

impact fragmentation ions for 2-chloroacetophenone, o-chlorobenzylidene malanonitrile and dibenz[b,f]1:4-oxazepine by capillary column GC-MS/MS (gas chromatography– mass spectrometry/mass spectrometry). Standardization of the collision dissociation cell conditions produced spectra suitable for identification and quantification. A detection limit of 100 pg was achieved for dibenz[b,f]1:4-oxazepine, the compound having the highest molecular mass. Allinson and McLeod (1997a) reported detection limits of 0.1 g, 25 mg, and 5 mg, respectively, for CN, CS and cayenne pepper from tear gas residues using ion mobility spectrometry in the negative ion acquisition mode at ambient temperature and atmospheric pressure. Some of the factors influencing the detection limits were attributed to vapor pressure, proton affinity, and electronegativity of the target molecule. Differentiation between CN and CS was enhanced because the latter, CS, was not detected in the positive ion acquisition mode (Allinson and McLeod, 1997b). Ion mobility spectrometry minimized sample preparation prior to spectral measurement. Allinson et al. (1998) reported on the utility of a hand-held ion mobility spectrometry for characterizing CN and CS tear gas sprays from the standpoints of speed of response, portability, detection limits, and secondary information available from the spectra. The 1H and 13C[1H] NMR spectra of the tear gases CN, CR, and CS in deuterated chloroform, deuterated dichloromethane and deuterated acetone have been recorded and analyzed (Mesilaakso, 1996). The assignments of the resonances were confirmed by homonuclear and heteronuclear correlation spectroscopy, and detailed 1H spectral parameters were determined by iterative analysis. The conformations of CR and CS were determined on the basis of the long-range coupling constants (4)J(, ortho), (5)J(, meta) and (6)J(, para). 1H spectral parameters of CR were used to simulate a reference spectrum for a test sample.

o-chlorobenzylidene malononitrile (CS) o-chlorobenzylidene malononitrile, CAS Registry Number 2698-41-1, has the military designation CS. It is also known as [(2-chlorophenyl)methylene]-propandinitrile, , -dicyano-orthochlorostyrene and o-chlorobenzalmalonylnitrile. Riot control agent CS replaced CN as the standard issue tear gas for the US Military in the late 1950s. Synthesis Chlorobenzylidene malononitrile was among the compounds prepared by condensing malononitrile with aldehydes (Corson and Staughton, 1928). The military designation (CS) was derived from the beginning letters of the chemists’ surnames. Of the ten compounds they prepared, p-methoxybenzal malononitrile, p-hydroxybenzal malononitrile and o-chlorobenzal malononitrile had irritant effects – as described by Corson and Staughton, “In sneezing caused by o-chlorobenzal malononitrile the face smarts, especially if damp. The smarting is intensified by washing. Most of the discomfort can be avoided if a gas mask is worn whenever the dry solid is handled. However, the majority of the dinitriles reported in this paper have no irritant effect.” The dinitriles were prepared by dissolving equivalent quantities of aldehyde and malononitrile in a suitable solvent, adding a few drops of piperidine and shaking the mixture. The solid, crystalline condensation product usually formed within 15 min. CS is a white solid with a molecular mass of 188.6 dalton corresponding to a molecular formula of C10H5N2Cl. The molar solubility in water at 20C is 2.0 104 mols/L ( ~4 mg/100 mL). Dissolved o-CS is rapidly hydrolyzed to o-chlorobenzaldehyde and malonylnitrile. The t1/2 is 14 min at pH 7.4 and 25C. However, Agent CS is persistent in the environment because its solubility in water is limited. The melting point and



boiling point are 95–96C and 310–315C, respectively. The vapor pressure is 3.4 105 torr at 20C. The vapor is several times heavier than air. The actual vapor density depends upon the means by which the agent is dispersed. Analysis The identification and quantification of CS is described in (Jane and Wheals, 1972; Zerba and Ruveda, 1972; D’Agostino and Provost, 1985; D’Agostino and Provost, 1995; Mesilaakso, 1996). Makles (1995) found that the reactions with 1,4-naphthoquinone and Marquis Reagent and with benzofurazane dioxide were useful for the detection of CS. Stankov and Lysenko (1997) developed four titrametric methods for the determination of CS using 2-dialkylaminoethane-thiols. Chlobowska et al. (1994) have reported a method for the determination of residues on clothing from CS and CN in tear gases. Specimens of cloth sprayed with CS or CN were heated to 60C in sealed jars, and the head space vapor was examined by gas chromatography. Alternatively, the sprayed cloth was extracted with hexane, and the hexane was examined by gas chromatography. Hexane extraction was more sensitive than head space analysis. The recovery of CS from the sprayed cloth decreased with the passage of time. Appearance in the chromatogram of peak corresponding to 2-chlorobenzaldehyde indicated hydrolysis of CS. Recovery of CN, on the contrary, remained constant over several weeks. The recovery of CS, CN, and the synthetic capsaicinoid nonivamide from dichloromethane extracts of treated absorbent cotton was investigated by GC-MS (gas chromatography – mass spectrometry) (Kataoka et al., 2002). The capsaicinoid was quantitatively recovered. Recovery of CS gradually decreased (due to hydrolysis), but CN was rapidly lost to the walls of the container. Smith et al. (2002) have described an application of solid phase microextraction sampling to the determination of CS by GC-MS in the field. They cite the elimination of an extraction solvent, the minimization of sample preparation, the suitability to volatile and semi-volatile analytes, and speed and portability as advantages of solid phase microextraction sampling. Using this approach, they observed more than 20 peaks in the TICs from the oxidizer supported combustion products of a civilian police-type CS canister. McNamara (1971) reported the following products after pyrolytic decomposition of CS in oxygen: CS, CO, CO2, H2O, HCl, HCN, NH3, N2O, and C2H2. Further research on the composition of the thermal decomposition products from CS was stimulated by the events at the Branch Davidians’s Mount Carmel compound near Waco, Texas, on April 19, 1993. Among the heat-dispersed, airborne CS degradation products reported by Kluchinsky et al. (2001, 2002) were 2-chlorobenzaldehyde, 2-chlorobenzylmalononitrile, 2-chlorobenzolnitrile, 2-chlorobenzylcyanide, cis and trans isomers of chlorocinnamonitrile, 2-chlorodihydrocinnamonitrile, 3-(2-chlorophenyl)propylnitrile, cis and trans isomers of 2-cyanocinnonnitrile, 1,2-dicyanobenzene, quinoline, 3-quinoline carbonitrile, and 2,2-dicyano-3-(2-chlorophenyl)oxirane. Samples of the particulate material formed by thermal dispersion from commercial CS canisters were collected on PTFE filters, recovered by extraction of the filters with 3 mL of dichloromethane and analyzed by GC-MS using a 30-m, DB-5 open tubular column. CS was the dominant compound in all samples. Several of the compounds observed in the samples collected from CS riot control canisters were not observed in samples from temperature-controlled, laboratory tube furnace experiments.

Dibenz[ b,f]1:4-oxazepine (CR) Dibenz[b, f]1:4-oxazepine has CAS Registry Number 257-07-8 and military designation CR.


RIOT CONTROL AGENTS

Synthesis CR can be prepared in a four-step synthesis beginning with an Ulman-type reaction between 1-chloro-2-nitro-benzene and phenol. The nitrophenoxy benzene product was reduced to the corresponding amine with steam and iron filings. Formylation of the phenoxyaniline produced the corresponding formamide, which was converted to the dibenzoxazepine upon treatment with polyphosphoric acid. Wardrop et al. (1976) used this four-step synthesis to prepare more than a dozen related compounds none of which was significantly more potent than CR. In their hands, the yields for each step of the CR synthesis were 80%, 70%, 90%, and 88%, respectively. CR is a pale yellow solid with a molecular mass of 195.1 dalton corresponding to a molecular formula of C13H9ON. Dibenz [b,f ]1:4-oxazepine is soluble in acetone, benzene, dichloromethane, and alcohols. Its molar solubility in water is 3.5 104 mols/L ( ~7 mg/100 mL) at 20C, and its melting and boiling points are 71–72C and 335C, respectively. The vapor pressure of the solid is 5.9 105 torr at 20C. The vapor is 6.7 times heavier than air. Analysis Thin layer chromatography (TLC) has been applied to the detection of CR in the presence of CN and CS (Makles et al., 1999). Detection limit was approximately 1 g in the spot. Ahmed (2000) has used solid phase extraction followed by gas chromatography to determine CR in water samples. Identification was made on the basis of retention index. Mass spectrometry was used for verification of suspect agent.

Oleoresin capsicum (OC)/capsaicinoids OC is the reddish-brown liquid obtained by extracting dried, ripe fruit of chili peppers, usually Capsicum annuum and Capsicum frutescenes. OC is a mixture of many compounds. Its composition is variable and depends upon factors such as maturity of the fruit and the conditions of the extraction. More than a hundred different compounds have been identified in OC. Among the branched-chain and straight-chain alkyl vanillamides isolated from OC is capsaicin, N-[(4-hydroxy-3-methoxyphenyl)methyl]-8-methyl-6-nonenamide. Capsaicin is the major pungent component in many peppers, and it is particularly noted for its irritant properties. Depending on the variety of chili pepper, OC may contain from 0.01% to 0.1% capsaicinoids on a dry mass basis. Some of the capsaicinoids found in OC are capsaicin, CAS RN 404-86-4 (~70%), dihydrocapsaicin, CAS RN 19408-84-5 (~20%), norhydrocapsaicin, CAS RN 28789-35-7 (~7%), homocapsaicin, CAS RN 58493-48-4 (~1%), and homodihydrocapsaicin, CAS RN 279-06-5 (~1%) (Cooper et al., 1991). Constant and Cordell (1996) successfully identified nonivamide as a minor (~0.25%) capsaicinoid in the OC from Capsicum annuum. Another important component of OC thought to be involved in the manifestation of its irritant properties is 3B,3S,5R-3-3-dihydroxy-, k-caroten 6-one. Formulations of OC are finding increased adoptions by law enforcement agencies. Synthesis The synthesis of capsaicin and the other capsaicinoids and some related compounds have been reported by Nelson (1919), by Jones and Pyman (1925), by Kobayashi (1927) and by Spaith and Darling (1930). Analysis Jane and Wheals (1972) employed TLC for the identification of capsaicin in OC-based formulations of tear gas aerosol sprays. They observed two zones having Rf values of 0.54



and 0.63 for capsaicin. The silica gel plates were developed with benzene–ethanol–ethyl acetate, and the zones were visualized with ferric chloride–potassium ferricyanide. Approximately 10 g of capsaicin was needed for successful visualization. Other lacrimators were not detected by the ferric chloride–potassium ferricyanide visualization agent. Reverse phase high performance liquid chromatography (HPLC) preceded by a silica clean up procedure has been described by Krebs et al. (1982) for the determination of capsaicin, CN, and CS in tear gas formulations. Fung et al. (1982) have used TLC followed by infrared spectrometry and HPLC followed by GC-MS to identify the capsaicinoids in tear gas sprays. Using GC-MS, Haas et al. (1997) found “… a multitude of natural compounds at irregular concentrations,…” in samples of OC sprays produced by two suppliers. Significant differences in composition were observed between the two samples. The sample from supplier A contained many more organic constituents in its formulation perhaps reflecting differences in the sources and preparations of the oleoresins. For example, the carboxylic acids, essential oils, and terpenes found in sample A were absent in sample B. Recently, Reilly et al. (2001) reported the development of liquid chromatography–tandem mass spectrometry (LC-MS-MS) methodology for the analysis of capsaicinoids in “pepper spray” products. Reilly and colleagues have also developed an LC/MS method for the determination of “pepper spray” residues on fabric (Reilly et al., 2002a) as well as a sensitive and selective method (liquid chromatography–tandem mass spectrometry) for the analysis of capsaicin and analogs in biological matrices (Reilly et al., 2002b).

3.2.2 Obsolete RCAs Bromoacetone (BA) Agent BA is known by the chemical names 1-bromo-2-pentanone and bromoacetone. CAS Registry Number 598-31-2 has been assigned to this compound. Agent BA was employed during the First World War. It is obsolete now for use as an RCA. Bromoacetone has been prepared by the bromination of acetone under a variety of conditions (Jackson and Jackson, 1935). Bromoacetone is a colorless liquid having a density of 1.634 at 23C. Its boiling and freezing points are, respectively, 135.5C and 54C. The vapor pressure of bromoacetone is 1 torr at 10C and 9 torr at 20C. Its molecular mass is 137.0 dalton. Bromoacetone decomposes to hydrogen bromide and a dark colored resinous solid in the presence of sunlight. Bromoacetone is among the volatile organic compounds determined by US EPA Method 8260. This method is applicable neatly to all sample matrices regardless of water content including various air sampling media. The volatile compounds are introduced to the gas chromatograph by the purge-and-trap method. The analytes are chromatographed on a temperature-programmed, wide-bore capillary column and identified and quantified with a mass selective detector. Using quadrapole instrumentation, the estimated quantitation limit is approximately 5 g/L (US EPA, 1996). The M90-1D-C ion mobility spectrometer is applicable to monitoring BA as well as other RCAs. The M90-1D-C ion mobility spectrometer is a field instrument used by the military for the detection of chemical warfare agents. The internal library parameters of this instrument can be modified for detection of acrolein, benzylbromide, bromoacetone, chloroacetone, chloropicrin, diphenylchloroarsine, diphenylcyanoarsine, ethyl bromoacetate, ethyl iodoacetate, and xylyl bromide (Environics, 2002).

Agent PS Agent PS has the chemical name trichloronitromethane and the CAS Registry Number 76-06-2. Agent PS is known also as chloropicrin, acquinite, klop, G8, and NC. Agent PS


RIOT CONTROL AGENTS

was used in large quantities during the First World War, and it was stockpiled during the Second World War. Its use as an RCA is now obsolete (CHPPM, 1996). The preparation of chloropicrin has been reviewed by Jackson (1934). It was first produced by the action of bleach on picric acid. Chloropicrin is an oily liquid with melting and boiling points of 67C and 212C, respectively. The molecular mass is 164.4 dalton, and the solubility in water is 23 mg/100 mL at 0C. At 20C, the vapor pressure is 16.9 torr.

Agent SK Ethyl iodoacetate has military designation Agent SK. Ethyl iodoacetate has been prepared by treating an alcoholic solution of ethyl bromoacetate with finely powdered potassium iodide, or by the reaction between ethyl chloroacetate and an ethereal solution of potassium iodide (Jackson and Jackson, 1935). Ethyl iodoacetate is a colorless liquid boiling at 179C. It decomposes in sunlight with the liberation of iodine. Ethyl iodoacetate is among the RCAs detected by the M90-1D-C ion mobility spectrometer mentioned earlier.

Agent CA Agent CA, 4-bromophenylacetylnitrile, CAS Registry Number 5798-79-8, is also known as bromobenzyl cyanide, -bromophenylacetonitrile, -bromo--tolunitrile, camite, and larmine. Agent CA was among the first tear gases used in the First World War. Within a decade, it was replaced by agent CN (CHPPM, 1996). Bromobenzyl cyanide is commonly produced in a three-step synthesis (Compton, 1987). First toluene is chlorinated to form benzyl chloride. Next is the formation of benzyl cyanide by reaction with an alcoholic sodium cyanide solution. This is followed by reaction with bromine vapor in the presence of sunlight to form bromobenzyl cyanide. Bromobenzyl cyanide has been prepared also by the action of bromine on benzyl cyanide at 125C and by the reaction of cyanogen bromide with an alcoholic solution of benzylbromide in the presence of sodium ethoxide (Jackson and Jackson, 1935). Pure bromobenzyl cyanide is a colorless solid having a molecular mass of 196.0 dalton. Its melting and boiling points are 25.5C and 242C, respectively. The vapor pressure is 1.1 102 torr at 20C, and the vapor is 6.7 times heavier than air. The density of the solid is 1.52 g/cm3 at 20C. That of the liquid is 1.47 g/cm3 at 25C. Bromobenzyl cyanide is soluble in chloroform, ether, and acetone, but its solubility in water is very limited.

3.3 STERNUTATORS Compounds developed as sternutators are listed in Table 3.3. Chemicals having the military designations DA, DC, and DM are also known as vomiting agents.

TABLE 3.3 Compounds used as sternutators Military designation

CAS no.

Chemical names

Agent DA Agent DC Agent DM

712-48-1 23525-22-6 578-94-9

Diphenylchloroarsine Diphenlycyanoarsine 10-Chloro-5,10-dihydrophenarsazine



Agent DA The chemical name for Agent DA is diphenylchloroarsine or diphenylarsenous chloride. It has been called Clark I, Blue Cross, and DIK also. Diphenylchloroarsine has been prepared from triphenyl arsine and arsenic trichloride under a variety of temperature and pressure conditions. These as well as other syntheses have been reviewed by Jackson (1935). Diphenylchloroarsine is a solid melting at 41C and boiling with decomposition at 333C. Its vapor pressure is 3 104 torr at 25C and 3.9 103 torr at 45C.

Agent DC Agent DC has the chemical name diphenylcyanoarsine or cyanodiphenylarsine, and it has been referred to as Clark II. Diphenylcyanoarsine has been prepared by treating diphenylarsenous oxide with dry hydrogen cyanide ( Jackson,1935). Diphenylcyanoarsine is a solid melting at 31.5C and boiling with decomposition at 350C. Its vapor pressure at 45C is 2 104 torr.

Agent DM In addition to its military designation, agent DM is known as 10-chloro-5, 10-dihydrophenarsazine, dihydrochlorophenarsazine, diphenylaminochloroarsine, and Adamsite. Adamsite was named for Roger Adams, the University of Illinois chemist who was head of Organic Unit 2 during the First World War. This unit was tasked to develop an efficient synthesis for diphenylchloroarsine, Agent DA, since the method used by the Axis was unknown to the Allies. At the suggestion of David Worrall, Adams directed his unit to focus on diphenylaminearsine, the synthesis of which appeared simpler. The compound was prepared and found to have sternutator properties when dispersed as a smoke from flares. This smoke could penetrate gas masks, force the wearer to unmask and thus be exposed to a lethal gas present on the battlefield. Adamsite, like Lewisite, the vesicant developed by Winford Lee Lewis from Northwestern University, was not produced in time to be used during the War ( Jones, 1983). 10-chloro-5, 10-dihydrophenarsazine is among the many compounds formed in the reaction between diphenyl amine and arsenic trichloride. Jackson (1935) has reviewed the preparation of diphenylaminechloroarsine. Purified 10-chloro-5,10-dihydrophenarsazine forms yellowgreen crystals. They melt at 195C and boil with decomposition at 410C. The vapor pressure of the crystals is 4.5 1011 torr at 25C. Adamsite is soluble in acetone, 13 g/100 g at 15C. Its water solubility is only 6.4 mg/100 g. Mesilaakso et al. (1997) measured and analyzed the 1H and 13C[1H] NMR spectra of diphenyl chlorophenylarsine, diphenylcyanoarsine and 10-chloro-5,10-dihydrophenarsazine. Diphenylchloroarsine and diphenylcyanoarsine are among the RCAs detected by the M90-1D-C ion mobility spectrometer mentioned above.

3.4 CONCLUSION Synthetic organic chemistry has produced an array of compounds with lacrimator and/ or sternutator properties for use as RCAs. Many of these have been withdrawn from use and are now obsolete as more potent, less toxic replacements became available. Continued advancements in analytical chemistry made possible the identification and quantification of RCAs, their residues and their decay products at ever decreasing concentrations.


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REFERENCES AHMED, I. (2000) Verification of a tear gas and a pesticide at trace levels in a water sample, Journal of the Chemical Society of Pakistan, 22(1): 21–26. ALLINSON, G. and MCLEOD, C.W. (1997a) Characterization of lachrymators by ambient temperature ion mobility spectrometry, Journal of Forensic Sciences, 42(2): 312–315. ALLINSON, G. and MCLEOD, C.W. (1997b) Characterization of tear gas residues by ion mobility spectrometry, Applied Spectrometry, 51(12): 1880–1889. ALLINSON, G., SAUL, C., MCLEOD, C.W., and GILBERT, J. (1998) Identification of tear gases in suspect spray cans and cloth samples by ion mobility spectrometry, Journal of Forensic Sciences, 43(4): 845–849. BALLANYTNE, B. (1977) Riot control agents (Biomedical and health aspects of the use of chemicals in civil disturbances). In: R.B. SCOTT and J. FRAZER (eds), Medical Annual, Bristol: Wright and Sons, pp. 7–41. CHPPM (1996) Detailed and General Facts About Chemical Agents – TG 218, US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD. CHLOBOWSKA, Z., CHUDZIKIEWICZ, E., and HEBENSTREIT, J. (1994) Studies on identification of tear gas traces, Z. Zagadnien´ Nauk Sa˛dowych, XXX: 28–33. COMPTON, J.A.F. (1987) Military Chemical and Biological Agents, Caldwell, NJ: Telford Press, p. 210. CONSTANT, H.L. and CORDELL, G.A. (1996) Noniramide, a constituent of capsicum oleoresin, Journal of Natural Products, 59: 425–429. COOPER, T.H., GUZINSKI, J.A., and FISHER, C. (1991) Improved high performance liquid chromatography method for the determination of major capsaicinoids in capsicum oleoresins, Journal of Agricultural and Food Chemistry, 39: 2253–2256. CORSON, B.B. and STAUGHTON, R.W. (1928) Reactions of Alpha, Beta Unsaturated Dinitriles, Journal of the American Chemical Society, 50: 2825–2837. D’AGOSTINO, P.A. and PROVOST, L.R. (1985) Gas chromatographic retention indices of chemical warfare agents and simulants, Journal of Chromatography, 331: 47–54. D’AGOSTINO, P.A. and PROVOST, L.R. (1995) Analysis of irritants by capillary column gas chromatography tandem mass spectrometry, Journal of Chromatographic Analysis, 695: 65–73. Environics (2002) http://www.environics.fi/products/m90. FUNG, T., JEFFERY, W., and BEVERIDGE, A.D. (1982) The identification of capsaicinoids in tear gas spray, Journal of Forensic Sciences, 27(4): 812–821. HAAS, J.S., WHIPPLE, R.E., GRANT, P.M., ANDRESEN, B.D., VOLPE, A.M., and PELKEY, G.E. (1997) Chemical and elemental comparison of two formulations of oleoresin capsicum, Science and Justice, 37: 15–24. HU, H. (1992) Toxicodynamics of riot control agents (lacrimators). In: S.M. SOMANI (ed.), Chemical Warfare Agents, New York: Academic Press Inc., pp. 271–288. JACKSON, K.E. (1934) Chloropicrin, Chemical Reviews, 14(2): 251–286. JACKSON, K.E. (1935) Sternutators, Chemical Reviews, 17(2): 251–292. JACKSON, K.E. and JACKSON, M.A. (1935) Lachrymators, Chemical Reviews, 15(2): 195–242. JANE, I. and WHEALS, B.B. (1972) Chromatographic characterization of lachrymatory agents in tear gas aerosols, Journal of Chromatographic Analysis, 70(1): 151–153. JONES, E.S.C. and PYMAN, F.L. (1925) Relation between chemical constitution and pungency in acid amides, Journal of the Chemical Society, 127: 2588. JONES, D.P. (1983) Chemical warfare research during World War I. In: J. PARASCANDOLA and J.C.WHORTON (eds), Chemistry and Modern Society, Washington, DC: American Chemical Society, pp. 165–185. KATAOKA, M., SETO, Y., TSUGE, K., and NOAMI, M. (2002) Stability and detectability of lachrymators and their degradation products in evidence samples, Journal of Forensic Sciences, 47(1): 44–51.



KLUCHINSKY, T.A., SAVAGE, P.B., SHEELY, M.V., THOMAS, R.J., and SMITH, P.A. (2001) Identification of CS-derived compounds formed during heat-dispersion of CS riot control agent, Journal of Microcolumn Separations, 13(5): 186–190. KLUCHINSKY, T.A., SHEELY, M.V., SAVAGE, P.B., and SMITH, P.A. (2002) Formation of 2-chlorobenzylidenemalonylnitrile (CS riot control agent) thermal degradation products at elevated temperatures, Journal of Chromatographic Analysis, 952: 205–213. KOBAYASHI, S. (1927) Relation between chemical constitution and pungency in acid amides, Scientific Papers of the Institute for Physical Chemistry Research, Tokyo, 6: 166. KREBS, J., PRIME, R.J., and LEUNG, K. (1982) Rapid determination of capsaicin, CN and CS in tear gas by HPLC, Canadian Society of Forensic Sciences Journal, J., 15(1): 29–33. MAKLES, Z. (1995) Detection mechanism of some chemical incapacitating warfare agents, Chemia Analityczna, 40(5): 755–765. MAKLES, Z., SLIWAKOWSKI, M., and SOKOLOWSKI, M. (1999) Detection of dibenzo [b,f ] [1,4] oxazepine in the presence of other lachrymators with thin layer chromatograph, Chemica Analityczna, 44(2): 257–262. MCNAMARA, B.P. (1971) The cyanide portion of the CS molecule, Edgewood Arsenal Special Publication, EASP 1100–2. MESILAAKSO, M. (1996) Analysis of the 1H and 13C[1H] NMR spectral parameters of the tear gases, -chloroacetophenone, dibenz [b,f] [1,4] oxazepine, and 2-chlorobenzylidine malononitrile, Magnetic Resonance Chemistry, 34(12): 989–994. MESILAAKSO, M., TOLPPA, E.-L., and NOUSIAINEN, P. (1997) Analysis of the 1H and 13C[1H] NMR spectral parameters of diphenylchlorophenylarsine, diphenylcyanoarsine and 10-chloro-5,10-dihydrophenarsazine: identification of the compounds through reference to simulated spectra, Applied Spectroscopy, 51(5): 733–737. NELSON, K.E. (1919) Vanillylacyl amides, Journal of the American Chemical Society, 41: 2121–2130. OLAJOS, E.J. and SALEM, H. (2001) Riot control agents: pharmacology, toxicology, biochemistry and chemistry, Journal of Applied Toxicology, 21: 355–391. REILLY, C.A., CROUCH, D.J., YOST, G.S., and FATAH, A.A. (2001) Determination of capsaicin, dihydrocapsaicin, and nonivamide in self-defense weapons by liquid chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry, Journal of Chromatography A, 912: 259–267. REILLY, C.A., CROUCH, D.J., YOST, G.S., and ANDRENYAK, D.M. (2002a) Detection of pepper spray residues on fabrics using liquid chromatography–mass spectrometry, Journal of Forensic Sciences, 47: 37–43. REILLY, C.A., CROUCH, D.J., YOST, G.S., and FATAH, A.A. (2002b) Determination of capsaicin, nonivamide, and dihydrocapsaicin in blood and tissue by liquid chromatography– tandem mass spectrometry, Journal of Analytical Toxicology, 26: 313–319. SALEM, H., OLAJOS, R.J., and KATZ, S.A. (2001) Riot control agents. In: S.M. SOUMANI and J.A. ROMANO (eds), Chemical Warfare Agents: Toxicity at Low Levels, Boca Raton, FL: CRC Press, pp. 321–372. SCHAEFER, R. and SONNENBERG, T. (1963) Chlorination of ketones with selenium oxychloride, Journal of Organic Chemistry, 28: 1128. SIDELL, F.R. (1997) Riot control agents, in Textbook of Military Medicine: Medical Aspects of Chemical and Biological Warfare, Washington, DC, Office of the Surgeon General, US Army, TMM Publications, Borden Institute, pp. 307–324. SMITH, P.A., KLUCHINSKY, T.A., SAVAGE, P.B., ERICKSON, R.P., LEE, A.P., WILLIAMS, K., STEVENS, M., and THOMAS, R.J. (2002) Traditional sampling with laboratory analysis and solid phase microextraction sampling with field gas chromatograph/mass spectrometry by military industrial hygienists, American Industrial Hygiene Association Journal, 63(3): 284–292. SPAITH, E. and DARLING, S.F. (1930) Synthesis of capsaicin, Chemistry Berlin, 63: 737–743. STANKOV, I.N. and LYSENKO, V.V. (1997) Titrimetric determination of o-chlorobenzal malononitrile and some other , -unsaturated compounds, Journal of Analytical Chemistry, 52(2): 171–177.


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US Environmental Protection Agency (US EPA) (1996) Method 8260B volatile organic compounds by gas chromatography/mass spectrometry (GC/MS), Washington, DC. WARDROP, A.W.H., SAINSBURY, G.L., HARRISON, J.M., and INCH, T.D. (1976) Preparation of some dibenz[b,f][1,4]oxazepines and dibenz[b,e]azepines, Journal of the Chemical Society Perkin I, 1279–1285. ZERBA, E.N. and RUVEDA, M.A. (1972) Gas chromatographic determination of riot-control agents, Journal of Chromatographic Analysis, 68: 245–247.

DISCLAIMER NOTICE The contents of this chapter do not reflect the position, policy or practice of any government agency. Responsibility for the contents of this chapter resides solely with the authors.


CHAPTER

Biochemistry, Biological Interactions, and Pharmacokinetics of Riot Control Agents

4

EUGENE J. OLAJOS US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, MD 21010

4.1 INTRODUCTION Biochemical and pharmacokinetic studies of riot control agents (RCAs) deal with the metabolism, mechanisms/modes of action, absorption, distribution, and elimination of these agents as studied in animals and humans. Such studies not only provide a quantitative basis for the toxicology of RCAs but also provide critical insights as to the mechanisms/modes of action that underpin both the pharmacological and adverse health effects of these compounds. The pharmacokinetics (absorption, uptake, distribution/ disposition, and elimination) of riot control agents is discussed initially. The metabolism of RCAs is subsequently presented examining the various pathways – both Phase I and Phase II metabolic processes that are involved in the bioconversion of these chemicals. Discussion continues focusing on the biological interactions and modes of action of RCAs and the relationship to toxic manifestations and adverse health effects.

4.2 UPTAKE AND DISTRIBUTION OF RCAS The uptake and distribution of RCAs have been examined in some detail for the RCAs dibenz[b,f]1:4-oxazepine (CR), 2-chlorobenzylidene malononitrile (CS), and capsaicin, which is the active component of oleoresin capsicum (OC). The uptake, metabolism, and disposition of the RCA 2-chloroacetophenone (CN) have not been characterized despite a history of extensive use and application.

4.2.1 Uptake and distribution of CS CS is quickly absorbed following inhalation exposure and rapidly distributed by the blood throughout the body. Pharmacokinetic studies have indicated that following inhalation exposure, CS is very rapidly removed from circulation – blood half-life is under 30 s. Short blood half-lives were noted for the major CS metabolites (2-chlorobenzyl


RIOT CONTROL AGENTS

malononitrile (dihydro-CS, CSH2 ) and 2-chlorobenzaldehyde (o-CB) ); however, there was wide species variation in the half-lives of these metabolites. In all species, the disappearance of CS, o-CB, and CSH2 in blood appeared to follow first-order kinetics. Human studies by Leadbeater (1973) on the respiratory uptake and metabolic fate of CS have indicated the presence of trace amounts of CSH2 in the blood. However, CS and o-CB were not detected following exposure to a high inhalation dose of CS (Ct 90 mg-min/m3). The findings by Leadbeater (1973) are in agreement with the maximum tolerable concentration in humans, which is below l0 mg/m3, and with CS uptake studies conducted in animals. It was theorized that significant amounts of CS would not be absorbed following inhalation to CS at or near the tolerable concentration.

4.2.2 Uptake and distribution of CR Aerosols of CR are rapidly absorbed from the respiratory tract, and the plasma half-life (t1/2) of CR after inhalation exposure to CR aerosol is about 5 min, which is consistent with the plasma half-life of CR following intravenous (i.v.) administration (Upshall, 1977). Studies by French et al. (1983a) demonstrated the effective uptake of CR from the GI tract, and that the metabolic fate of absorbed CR was generally similar to that following i.v. administration. The kinetics of CR and its metabolic products in blood was also investigated in the same study. Findings indicated that most of the blood radioactivity at 5 min was the lactam derivative, which decreased bi-exponentially with half-lives of 4 and 29 min, and that the parent compound was barely detectable at 1 h. The sulfate conjugates of the hydroxylactam products of CR metabolism appeared quickly in the vascular compartment. Results suggested that biliary 14C decreased steadily and that urinary 14C, a mixture of 4-,7-, and 9-hydroxylactam sulfates, was maximal at 2 h. In the same study (French et al., 1983a), whole-body autoradiography studies were also conducted in mice intravenously dosed with CR. The whole-body distribution of 14Clabeled-CR was consistent with the compound’s rapid disappearance from blood. Very rapid uptake of 14C was noted in highly perfused organs such as brain, small intestine, kidneys, and heart. The appearance of significant levels of 14C in the upper GI tract indicated high biliary excretion. The pattern of distribution was consistent with that of a highly lipophilic substance undergoing hepatic bioconversion, biliary secretion, enterohepatic circulation, and renal excretion. The eyes are among the most readily accessible organs in terms of their location in the body and represent a major target of peripheral sensory irritants. Not only are the eyes targets for systemic toxicity following exposure to industrial chemicals or drugs by other routes, but can themselves be a portal for systemic toxicity – in particular when exposure is to substances of high potency and toxicity. Thus, sufficient material may be absorbed to produce systemic effects. Furthermore, corneal tissue is known to possess metabolic conversion capabilities (King and Holmes, 1997). Since peripheral sensory irritants are highly potent substances with the potential for absorption following ocular instillation or exposure, Balfour (1978) studied the relationship between chemical sensory irritation and CR uptake and metabolism. In these studies, the absorption and metabolic fate of CR in intact cornea and corneal homogenates was investigated. Study findings indicated that corneal tissue readily took up CR and metabolized CR to its lactam derivative.

4.2.3 Uptake and distribution of CN Very little is known about the uptake and distribution of CN following exposure – the metabolic fate of CN is poorly characterized.


BIOCHEMISTRY AND PHARMACOKINETICS OF RCA

4.2.4 Uptake and distribution of capsaicin, capsaicinoids, and OC The distribution of capsaicin in tissues of rats following systemic administration was studied by Saria et al. (1982). There was rapid uptake into the central nervous system tissues, and high levels of capsaicin were detected following intravenous dosing. Distribution studies following subcutaneous (s.c.) administration of capsaicin revealed slow diffusion from the site of application; however, detectable levels of capsaicin were found in various tissues. Studies by Kim and Park (1981) suggested that capsaicin and its analogs were poorly absorbed from the GI tract, which led Kawada et al. (1984) to investigate further the gastrointestinal uptake of capsaicin and associated analogs in rats. Results demonstrated that absorption of capsaicin and dihydrocapsaicin occurred rapidly from the small intestine and stomach. Capsaicin/capsaicinoid uptake from these sites was approximately 85% of the administered dose. Regional capacities for uptake of capsaicin and its analogs were also investigated, and the results indicated regional differences in the absorption of capsaicin from the GI tract. The findings reported by Kawada et al. (l984) are in concordance with the in vitro results published by Monsereenusorn (l980) concerning the in vitro intestinal absorption of capsaicin. Absorption characteristics of capsaicin and capsaicinoids via a critical uptake route such as inhalation has not been elucidated.

4.3 METABOLISM OF RCAS The metabolism and metabolic fate of RCAs have been studied in considerable detail for agents such as CR, CS, and capsaicin (the active component of oleoresin capsicum) and to a lesser extent for agents such as CN. Before proceeding to detailed discussions concerning the metabolism of RCAs and their interactions with cellular processes and constituents, a general overview of xenobiotic metabolism is presented. The most common pathways of xenobiotic metabolism involve oxidation, reduction, hydrolysis, and conjugation. Metabolizing enzymes are localized in the microsomal, soluble, or mitochondrial fractions of tissue homogenate. Most chemicals and drugs are metabolized in the liver; however, extrahepatic metabolism may also contribute significantly to the bioconversion of xenobiotics. Toxicants generally undergo various types of biotransformation producing an array of metabolites and conjugated products. Often a chemical or drug is subjected to several competing pathways simultaneously, and the extent of formation of the various metabolites depends on the relative rates of the various interactions. Additionally, metabolic reactions proceed sequentially, and oxidation, reduction, or hydrolysis reactions are followed by conjugation. In the most general terms, the bioconversion or metabolism of foreign substances may be regarded as a detoxification, resulting in decreased toxicity (e.g. the conversion of benzoic acid to hippuric acid, hydrogen cyanide to sodium thiocyanate) or activation, which leads to enhanced toxicity (e.g. the conversion of acetaminophen to N-acetyl-benzoquinoneimine, the conversion of parathion to paraoxon, the conversion of CR to its lactam derivative, and the metabolism of capsaicin to -hydroxycapsaicin). The relative importance of various types of biotransformation of a toxicant depends on host, chemical, and environmental factors as well as the dose. Furthermore, the type of metabolic conversion depends on chemical structure and other factors such as route of exposure, species of animal, competing pathways of metabolism, gradient of a metabolic pathway across an organ, chiral factors, hormonal and nutritional status, age, and pathological state. The toxicity of a chemical can be greatly altered by these factors, and


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the metabolites usually resulting from different biotransformations are often markedly varied in their effects. The bioconversion of xenobiotics involves primary (Phase I) and secondary (Phase II) metabolism as depicted in Figure 4.1. The aforementioned system of classification was devised many years ago by Williams (1959), who studied the various biotransformation mechanisms involved in xenobiotic metabolism. Oxidation, reduction, and hydrolysis reactions are representative of Phase I metabolic processes, whereas glucuronic acid-, glutathione-, and sulfate-conjugations are illustrative of Phase II metabolic processes. Descriptions of the bioconversion and bioactivation of various classes of chemicals abound in the literature and are the subject of many reviews, book chapters, and monographs (Testa and Jenner, 1976; Dauterman, 1980; Hodgson and Dauterman, 1980; LaDu et al., 1982; Anders, 1985; de Bethizy and Hayes, 1989). Generally, the metabolic processes involved in Phase I metabolism result in a detoxification because the parent compound is converted into a more water soluble, readily excreted substance. However, toxic metabolites, which may be more toxic than the parent compound, can also be generated by the enzymes involved in Phase I pathways. The major enzyme systems, involved in the metabolism of xenobiotics, are highlighted in Table 4.1. Monoxygenase (cytochrome P-450-dependent) and carbonyl enzyme systems are involved in the metabolic conversion of RCAs and constitute an important determinant in RCA pharmacology and toxicology. Microsomal-mediated drug and xenobiotic oxidation represent important pathways of drug/xenobiotic biotransformation. Microsomal mixed-function oxidation reactions are catalyzed by a nonspecific multi-enzyme system, having cytochrome P-450 as the terminal oxidase, and is localized in the endoplasmic reticulum of the cell. The cytochrome P-450s are found in greatest abundance in the microsomal fractions of liver tissue isolates. Cytochrome P-450 and the other components of the mixed-function oxidase system are also found in extra-hepatic tissue (i.e. lung, skin, and gastrointestinal tract). The cytochrome P-450s are inducible by endogenous and some exogenous compounds. Cytochrome P-450 enzymes have been classified in terms of substrate specificity (Smith, 1991); however, a unified P-450 nomenclature system, based on amino acid sequence homology, is now widely used (Nebert et al., 1987, 1991). The role of cytochrome P-450 enzymes is central to the detoxification of lipophilic xenobiotics and drugs. These important enzyme systems are involved in endogenous and xenobiotic Phase I metabolism, catalyzing the introduction of oxygen into a substrate.

Phase I

• Primary products Ph

Phase I

• Secondary products II

• Drugs, insecticides, other foreign compounds

as

II

Ph

e

e

as

• Conjugated products (excretion) (Phase I) • Metabolic transformations Oxidation Reduction Hydrolysis Group transfer

(Phase II) • Metabolic transformations Conjugations with: Glucuronic acid Sulfate Glutathione Glycine

Figure 4.1: Primary (Phase I) and secondary (Phase II) metabolism of xenobiotics.



TABLE 4.1 The major enzyme systems involved in Phase I metabolism of xenobiotics Microsomal

Nonspecific multienyzme system localized in the endoplasmic reticulum Mixed-function oxidase system found in hepatic and extrahepatic tissues Reactions include: deamination, demethylation, dealkylation, hydroxylation, epoxidation, oxidation of alcohols and aldehydes

Hydrolases

Enzymes (amidases, carboxylesterases, phosphatases that cleave through hydrolysis) Found in hepatic, non-hepatic, and blood tissues

Reductions/ Reductases

Reactions that may or may not be enzymatically mediated Hepatic and non-hepatic sites Reactions include: reductive dehalogenation, reduction of aldehydes and ketones, reduction of nitro groups, double bond formation

The predominant reaction catalyzed by P-450 enzymes is as follows: RH O2 NADPH H → R-OH H2O NADP In addition to oxidation at carbon atoms, these enzymes also mediate oxidation reactions at nitrogen and sulfur atoms. The oxidation reaction facilitates further bioconversion processing by Phase II enzymes, which involves conjugation reactions with endogenous substances such as glucuronic acid, glutathione, and sulfate to yield a hydrophilic and excretable product(s). Of comparable toxicological significance is that many of the metabolites of P-450 mediated biotransformation are biologically active with the potentiality to induce adverse biological effects. In summation, one can state that studies of cytochrome P-450 enzymes and genes have greatly impacted many areas of biology and medicine to include drug and xenobiotic toxicity, mutagenesis and carcinogenesis, mechanisms and modes of action, drug–drug interactions, gene transcription, and control of gene expression. The reader is referred to the following literature pertaining to cytochrome P-450 enzyme function, structure, and role in drug and xenobiotic toxicity and adverse health effects (Porter and Coon, 1991; Guengerich, 1992, 1997; Henderson and Wolf, 1992; Ortiz de Montellano, 1995; Estabrook, 1996; Graham-Lorence and Peterson, 1996; Negishi et al., 1996; Whitlock, 1999). Carbonyl enzyme systems also have an important role in endogenous and Phase I metabolic processes (Felsted and Bachur, 1980; Persson et al., 1994; Petersen and Lindahl, 1997; Oppermann and Maser, 2000). Carbonyl enzyme systems comprise alcohol and aldehyde dehydrogenases (ADH, ALDH), aldo–keto reductases (AKR), short-chain dehydrogenases/reductases (SDR), and quinone reductase (QR). The ADHs and ALDHs, the latter consisting of a diverse set of enzymes, are involved in oxidative pathways. They function in intermediary metabolism, detoxification, and osmotic protection. ALDHs have broad substrate specificities and are involved in Phase I metabolism of xenobiotics, metabolism of lipid peroxidation products, in glycolysis, and in GABA, folate, and amino acid metabolism. Aldehydes are metabolized to carbonic acids or are converted to primary alcohols. Aldehydes are relatively potent electrophiles due to their chemical reactivity and can interact with nucleophilic moieties of proteins and nucleic acids.


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Carbonyl reduction involves the following enzyme systems: AKR, SDR, and QR. Presently, most carbonyl reducing enzymes are grouped into two protein superfamilies, namely, the AKR and the SDR (Bohren et al., 1989; Jornvall et al., 1995). The AKR family includes aldehyde reductase, aldose reductase, dihydrodiol dehydrogenases, and several recently studied putative reductases involved in drug metabolism and resistance (Hyndman et al., 1997). In mammals, the main cytosolic carbonyl reducing enzymes include aldehyde reductase (EC 1.1.1.2), carbonyl reductase (EC 1.1.1.184), and aldose reductase (EC 1.1.1.21). These enzymes are characterized by broad and overlapping substrate specificities, and in addition to their involvement in Phase I metabolism, they participate in the metabolism of endogenous substances (e.g. steroids and bile acids). In addition, microsomal carbonyl reducing enzymes have been shown to be involved in detoxification reactions (Maser and Oppermann, 1997). Reductive pathways represent important processes in the bioconversion of numerous aliphatic, alicyclic, and aromatic carbonyl compounds. The metabolic outcome is either inactivation or activation, depending on the compound. The formation of a hydroxyl group is illustrative of a major pathway in bioconversion to a more hydrophilic compound, and provides a metabolic intermediate that can be readily excreted following conjugation via glucuronidation or sulfation. Reductive quinone metabolism is of toxicologic significance since the stepwise reduction of quinone compounds leads to the formation of semiquinone radicals that can either be reduced to hydroquinones or reconverted to quinones. Both semiquinones and hydroquinones can undergo auto-oxidation by molecular oxygen, giving rise to reactive oxygen species, with potential for cellular damage. Furthermore, hydroquinones can be further metabolized via Phase II conjugation reactions thus attenuating redox-cycling. The subject of quinones and redox-cycling is discussed further in a subsequent section which addresses the metabolic conversion of capsaicin. Conjugation reactions (Phase II metabolism) also represent a common route of xenobiotic metabolism, and with few exceptions (e.g. certain glutathione and sulfate conjugates may become more toxic) Phase II reactions are associated with detoxification. The major conjugation pathways are summarized in Table 4.2. Conjugation reactions may occur when a drug or foreign substance contains a moiety, usually OH, COOH, NH2, or SH, which combines with a natural substance (i.e. glucuronic acid) to form a readily excretable water-soluble polar metabolite – the enhanced water solubility due to the presence of the

TABLE 4.2 Xenobiotic conjugation pathways Pathway

Substrates

Glucuronic acid conjugation

Alcohols, phenols, amines, aromatic and various aliphatic carboxylic acids, certain thiol compounds, and endogenous substances (i.e. steroids) Aromatic amines, certain aliphatic alcohols, phenols, and endogenous substances (e.g. steroids) Aromatic hydrocarbons, halogenated aromatic hydrocarbons, and aromatic amines Organic acids

Sulfate conjugation Glutathione conjugation (mercapturic acid synthesis) Amino acid conjugation (i.e. glycine) Acetylation (conjugation with endogenous acids)


Aromatic amino compounds, hydrazines, and sulfonamides


large hydrophilic carbohydrate moiety. If a drug or foreign substance does not contain these groups, it may acquire these through a Phase I reaction (i.e. oxidation). The bioconversion of RCAs, as with other foreign substances and drugs, involves both Phase I and Phase II metabolic processes.

4.3.1 Metabolism and fate of CS Metabolic studies on CS indicate that it undergoes extensive metabolism in mammalian species. In general, CS undergoes rapid hydrolysis in vivo and in vitro to form o-CB and malononitrile. The aldehyde undergoes further metabolism and subsequently conjugated, whereas the malononitrile intermediate is further broken down with the potential for cyanide formation, the latter is biotransformed to thiocyanate. Seminal studies on the metabolism and biological interactions of the riot-control agent CS were conducted by Cucinell et al. (1971) and Feinsilver et al. (1971) and subsequently investigated (Leadbeater, 1973; Leadbeater et al., 1973; Paradowski, 1979; Rietveld et al., 1983, 1986; Brewster et al., 1987). The primary metabolites are o-CB and dihydro-CS, which undergo further bioconversion and conjugation (refer to Figure 4.2). CS is rapidly hydrolyzed to 2-chlorobenzaldehyde, which undergoes metabolic transformation, namely, oxidation to 2-chlorobenzoic acid or reduction to 2-chlorobenzyl alcohol. Of note is that the bioconversion to o-CB is illustrative of a detoxification pathway leading to a reduction in the lethal potency of CS. The 2-chlorobenzoic acid intermediate undergoes subsequent glycine conjugation to yield 2-chlorohippuric acid – an example of condensation of a carboxylic acid containing compound with an amine. The 2-chlorobenzyl alcohol intermediate is conjugated and ultimately excreted as a cysteine addition product (2-chlorobenzyl acetyl cysteine or

Cl

Cl

9

9

CN

9

9

CN

CN

2-Chlorobenzylidene malononitrile (CS)

Cl

CN

CH2 9CH2

CH:C

Dihydro CS

:

O

CH

2-Chlorobenzaldehyde (o-CB) Cl

Cl CH2OH

2-Chlorobenzyl alcohol

COOH

2-Chlorobenzoic acid

Figure 4.2: Bioconversion of CS.


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as a glucuronate (1-O-(2-chlorobenzyl) glucuronic acid). Findings from in vitro studies conducted by Leadbeater et al. (1973) indicate that in blood, CS is metabolized via a NADPH-dependent reduction of the benzylidene double bond (olefinic side chain of CS) to yield dihydro-CS. Dihydro-CS is further metabolized to 2-chlorophenyl acetyl glycine and 2-chlorophenyl 2-cyanopropionate. Metabolic studies conducted by Feinsilver and coworkers (1971) indicated that the principal urinary metabolites of CS are 2-chlorobenzoic acid, 2-chlorohippuric acid, 2-chlorobenzyl glucuronic acid, and 2-chlorobenzyl cysteine. Minor metabolic products of CS metabolism were identified as 2-chlorobenzyl alcohol, 2-chlorophenyl acetyl glycine, and 2-chlorophenyl 2-cyanopropionate. Studies on the metabolic fate of CS in rats following intravenous and intra-gastric doses was subsequently investigated by Brewster and coworkers (1987). Results from these studies corroborated findings from previous metabolic studies on CS and provided compelling evidence that urinary excretion was the major elimination pathway for CS. Furthermore, Brewster and coworkers also provided evidence suggesting the conversion of CS to dihydroCS by stomach contents, which had been previously reported by Paradowski (1979). Metabolic studies to ascertain the metabolic fate of CS in various animal species following inhalation exposure to high concentrations of CS aerosol have been conducted (Leadbeater, 1973 and Leadbeater et al., 1973). CS along with its principal metabolites o-CB and dihydro-CS, was detected in the blood, but only after large inhalation doses. The generation of cyanide as a consequence of the metabolism of CS, coupled with the high toxicity associated with cyanide, has led to a number of studies with a focus on cyanide formation in the course of CS metabolism (Swentzel et al., 1970; Cucinell et al., 1971; Frankenberg and Sorbo, 1973; Leadbeater, 1973; Brewster et al., 1987). Patai and Rappoport (1962) demonstrated initially that malononitrile is a spontaneous hydrolysis product of CS, the former converted to cyanide in animal tissues (Nash et al., 1950; Stern et al., 1952). A study by Cucinell et al. (1971) reported the detection of free cyanide in dogs exposed to lethal doses of CS following i.v. administration; however, experimental details were lacking. It is of interest to note, that CS and malononitrile possess two nitrile residues and theoretically may give rise to two cyanide ions per molecule of the parent compound. As summarized by Ballantyne (1977) studies were conducted to test this postulate, and data suggest that under in vivo conditions only one cyanide radical is converted to cyanide, thus the total amount of cyanide generated may be minimal. Studies have also been conducted to ascertain cyanide production, measured as plasma thiocyanate levels, in human subjects exposed to CS (Swentzel et al., 1970; Leadbeater, 1973). Findings from these studies have indicated negligible levels of plasma thiocyanate. Brewster et al. (1987) conducted whole-body autoradiography studies on mice administered labeled-CS (14CN-CS). Findings indicated low levels of cyanide suggesting cyanide generation via the metabolic bioconversion of CS.

4.3.2 Metabolism and fate of CR Biotransformation and elimination pathways play an important part in xenobiotic toxicity, and the bioconversion and elimination of CR in various animal species have been studied in considerable detail (Balfour, 1978; Harrison et al., 1978; French et al., 1983a,b; Furnival et al., 1983). The metabolic fate and elimination of CR have been characterized in a series of in vivo and in vitro studies (French et al., 1983a,b; Furnival et al., 1983 ). CR undergoes hepatic metabolism, biliary secretion, enterohepatic circulation, and renal excretion. The comparative in vivo metabolism and metabolic fate of CR was studied by French et al. (1983a). Human metabolic studies on CR on the other hand have not been conducted owing to the very high sensitivity of humans to the irritant properties of CR. This high degree of sensitivity has precluded metabolic studies because the maximal



tolerated dosage is too low to allow for metabolic detection. Comparative metabolic studies on CR were conducted by French et al. (1983a) in rats, guinea pigs, and monkeys indicating that CR undergoes extensive metabolic conversion. Similar metabolites and excretory patterns were noted among the species, with urinary excretion as the major route of elimination. Findings indicate that the lactam derivative dibenz [b,f]1:4-oxazepin-11-(10H)-one (10,11-dihydrodibenz[b,f]1:4-oxazepin-11-one) is a primary metabolite and the precursor of the urinary hydroxylated metabolites. In the rat, metabolites of CR include dihydro-CR, the amino alcohol of CR (2-amino-2hydroxymethyldiphenyl ether), the lactam (dibenz[b,f]1:4-oxazepin-11-(10H)-one), hydroxylactams (4-, 7-, and 9-hydroxylactams), and possibly an arene oxide intermediate (Figure 4.3). The hydroxylactam intermediates, resulting from microsomal oxidation, undergo sulfate conjugation and are excreted in the urine as sulfates. In the rat, the major elimination pathway for CR is sulfate conjugation, which is irrespective of dose and the route of administration. Biliary excretion of CR metabolites may also occur in addition to sulfate conjugation. Glucuronide formation may also occur involving not only the hydroxylactams but the amino alcohol metabolite of CR as well. These products are ultimately excreted in the urine. French and coworkers (1983a) point out the similarity in metabolic products and excretory pathways; however, only free hydroxylactams were isolated from monkey urine. In vitro metabolic studies, which utilized rat liver preparations and isolated liver cells were also conducted by Furnival and coworkers (1983). Study results demonstrated that Phase I metabolism of CR involves the following metabolic processes: (a) ring opening and reduction of CR to form 2-amino-2hydroxymethyldiphenyl ether (the amino alcohol), (b) the oxidation of CR at C-11 to form the cyclic lactam, and (c) hydroxylation of the lactam by microsomal mixed function oxidases to the 4-,7-, or 9-hydroxylactams. The reactions responsible for bioconversion to the amino alcohol and the lactam are mediated by two different enzyme systems. The enzyme system, which produces the amino alcohol, closely resembles the aldehyde

O

O

NH2 CHO

NH2 CH2OH

Amino aldehyde

Amino alcohol

O O

:

N •C H O Arene oxide

5 O

8 9

N:CH 10 11

4 3

O

2

N•C H O

1

Dibenz[b,f] 1:4-oxazepine (CR)

:

6 7

Lactam

4 - OH

7 - OH O

:

N• C H O 9 - OH

Monohydroxylated derivatives 7-,9-,4-hydroxylactams

Figure 4.3: Metabolic pathways for CR.


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reductases (EC 1.1.1.2), which are known to have a broad range of substrate specificity and a broad tissue distribution (Leibman, 1971; Bachur, 1976; Wartburg and Wermuth, 1980). It is postulated that the substrate is the ring-opened amino aldehyde, which exists in equilibrium with the ring-closed form. The enzyme, which catalyzes the biotransformation of CR to its lactam, is localized in the cytosol fraction and appears to be unrelated to the reductase. The enzyme is not NADPH/NADH-dependent – a property characteristic of aldehyde oxidases (EC 1.2.3.1), which accept as substrates a wide range of aromatic heterocycles and aldehydes (Krenitsky et al., 1972; Stubley et al., 1979). The hydroxylactams and amino alcohol intermediates of CR metabolism undergo Phase II conjugation reactions. The hydroxylactams are rapidly sulfated for renal excretion. The amino alcohol metabolite of CR is conjugated via glucuronide for biliary secretion, intestinal resorption, and recycling. Biliary metabolites are resorbed and recycled until all of the amino alcohol is converted back to CR for ultimate renal excretion as the sulfate. Additionally, glucuronide conjugates of the hydroxylactams appear in the bile but are resorbed from the GI tract and eventually excreted in the urine as their sulfate conjugates. Additional in vivo and in vitro metabolic studies on CR were conducted by French et al. (1983b). Results from these studies supported previous conclusions that the major metabolic fate of CR in the rat is the oxidation to the lactam, subsequent ring hydroxylation, sulfate conjugation, and urinary excretion. With the exception of CR-lactam, Phase I metabolites of CR are acutely less toxic than the parent compound (French et al., 1983a). The literature is extant pertaining to studies focusing on non-hepatic metabolism of CR; however, extrahepatic metabolism of CR has been reported by Balfour (l978) and Furnival et al. (1983). The extrahepatic metabolism (lung, kidney, and small intestine) of CR was studied by Furnival et al. (1983). Labeled CR was incubated with microsomal and soluble fractions prepared from homogenates of lung, kidney, and small intestine. Overall, the metabolism of CR by the kidneys, lungs, and small intestine was quantitatively similar to that of the liver but yields were low. Essentially, CR was converted by these tissues to the amino alcohol and hydroxylactams. Discussion on the metabolism of CR is incomplete without mention and discussion regarding the potential for arene oxide formation. The metabolism of aromatic compounds to phenols involves biochemical processes directed toward accomplishing the detoxification and excretion of a variety of foreign substances. However, the metabolism of aromatic compounds is also associated with the formation of highly reactive arene oxide intermediates – the consequences being highly detrimental to cellular biochemistry and physiology. Arene oxides are strongly implicated in the toxic, mutagenic, and carcinogenic effects of aromatic compounds and provides a molecular basis for aromatic compound-induced cytotoxicity. Evidence for such intermediates in vivo is indirect and is based on the formation of dihydrodiols or mercapturic acid derivatives as metabolites or the observation of the NIH shift using appropriately labeled substrates (Daly et al., 1972; Jerina et al., 1973; Jerina and Daly, 1974). Arene oxides can isomerize to phenols but as “bioactivated intermediates” can also covalently bind with cellular biopolymers. The extent of binding depends on various factors, namely, the rate of formation of arene oxides, the rates of isomerization to phenols, and conjugation with glutathione. Harrison et al. (1978) investigated the potential of arene oxide generation during hydroxylation of CR. Their findings implicated the formation of an arene oxide intermediate in the hydroxylation of lactam to the 7-hydroxylactam of CR.

4.3.3 Metabolism and fate of CN The metabolism and full metabolic fate of CN has not been studied in great detail and consequently is poorly characterized. It is postulated that CN undergoes a metabolic



conversion to an alkylating agent having the capability to interact with SH groups and nucleophilic sites of macromolecules. Alkylation of SH-containing enzymes is known to result in enzyme inactivation with subsequent disruption of cellular processes. Historically, Mackworth (1948) had long ago studied the potential inhibitory effect of CN on a number of enzymes including cholinesterase (ChE). Based on the potential to disrupt enzyme function, Castro (1968) had also examined the effects of various alkylating agents, including CN, on human plasma ChE. CN inhibited ChE activity but not as a consequence of interaction with SH moieties. It was postulated that some of the toxic actions of CN may be due to alkylation of SH-containing enzymes.

4.3.4

Metabolism and fate of capsaicin and capsaicinoids

The bioconversion and metabolic fate of capsaicin and capsaicinoids is reasonably well understood and characterized. Capsaicin and capsaicinoids undergo Phase I metabolic conversion involving both oxidative and nonoxidative pathways. The liver is the site of the highest enzymatic activity followed by extrahepatic tissues (e.g. kidney, lung, and small intestine). The metabolic processes involved in the bioconversion of capsaicin and its analogs were studied initially by Lee and Kumar (1980). They demonstrated the conversion to catechol metabolites via hydroxylation on the vanillyl ring moiety, findings which were later confirmed by Miller et al. (1983). Kawada and Iwai (1985) studied in rats both the in vivo and in vitro metabolic conversion of dihydrocapsaicin an analog of capsaicin. Dihydrocapsaicin was metabolized to metabolic products that were excreted in the urine mostly as glucuronides. Metabolic conversion of capsaicin by the hepatic mixed-function oxidase system to an electrophilic epoxide is an example of bioconversion to a reactive metabolite. Other pathways resulting in the formation of highly reactive intermediates involve the formation of a phenoxy radical as well as the formation of a quinone type product (Surh and Lee, 1995) – also refer to a very recent article by Reilly et al. (2003). It is postulated that the generation of a quinone derivative proceeds via O-demethylation at the aromatic ring with concomitant oxidation to the semiquinone and quinone derivatives or via demethylation of the phenoxy radical intermediate of capsaicin (see Figure 4.4). Of additional note is that the quinone pathway, involving the phenoxy radical, leads to the formation of the highly reactive methyl radical. In addition to these oxidative pathways, studies by Wehmeyer et al. (1990) have demonstrated that the alkyl side chain of capsaicin is also susceptible to enzymatic oxidation, namely, oxidative deamination. Surh et al. (1995a) and subsequently Reilly et al. (2003) have provided evidence that capsaicinoids can undergo aliphatic hydroxylation (i.e. -hydroxylation). Via this pathway, capsaicin is metabolized to -hydroxycapsaicin – other analogs of capsaicin (i.e. nonivamide and dihydrocapsaicin) also undergo aliphatic hydroxylation. Surh et al. postulated that aliphatic hydroxylation of capsaicinoids represents a detoxification pathway. Nonoxidative metabolic processes are also involved in the bioconversion of capsaicin; for example, the hydrolysis of the acid–amide bond to yield vanillylamine and fatty acyl moieties (Kawada et al., 1984; Kawada and Iwai, 1985; Oi et al., 1992) (Figure 4.4).

4.4 MODES OF ACTION AND BIOLOGICAL INTERACTIONS OF RCAS Because of the great variability in chemical structure of RCAs, no single mechanism of action can account for the varied physiological and toxicological effects of these compounds. The underlying mechanism(s) of action to include both physiological and


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H3CO HO

CH2NHCO9R

N on pa oxi th da wa tiv y e

Capsaicin O x pa ida th tiv wa e y

H3CO H3CO CH2NHCO9R

HO CH2NH2 + R9COOH

HO

O Arene oxide Vanillylamine

O

H3CO •O

CH2NHCO9R Phenoxyradical

• CH3 O

CH2NHCO9R Quinone

Figure 4.4: Metabolic pathways envolving capsaicin.

toxicological effects of the riot control agents CR, CS, and capsaicin (the active component of OC) are better understood and more fully delineated than it is for other RCAs such as CN. A multiplicity of mechanisms and modes of action are responsible for the biological actions of these chemicals to include toxic/adverse effects. Although much of the following discussion focuses on adverse effects whose etiology stems from the interaction of reactive metabolites of RCAs with critical molecular targets, mechanisms of action may also involve less-highly reactive metabolites. When discussing the biological actions of reactive intermediates, one should keep in mind that different degrees of reactivity exist among these toxic intermediates, which influences the level of toxicity associated with a particular chemical. Thus, extremely reactive metabolites are likely to interact with many cellular targets, in close proximity of their formation. Whereas, less reactive intermediates may travel to distant sites within the cell and react with additional cellular targets (Nelson and Pearson, 1990). Interactions of electrophilic metabolites with nucleophilic moieties of biological material with potential consequences are highlighted in Figure 4.5. Discussion on the modes of action and adverse effects outcomes continues with an overview of toxic metabolic products such as reactive oxygen species (ROS) and cyanide. Adverse effects that may result from such toxic metabolites include mutagenesis, carcinogenesis, immunotoxicity, perturbations involving bioenergetic pathways, oxidation of macromolecules (i.e. DNA, proteins, and lipids), alteration of detoxication processes/capabilities, cytotoxicity, and the activation of signaling pathways involved in pathologic processes and carcinogenesis. The mechanisms by which some of these toxic metabolites (e.g. phenoxy radicals, quinones, •CH3, and ROS (e.g. superoxide, hydrogen peroxide, hydroxyl radical) ) can produce adverse effects may be straightforward or rather complex as in the case of toxic intermediates such as quinones.



Reactive metabolites (e.g. phenoxy radicals, quinones, ring epoxides)

Reactive oxygen species (ROS) (e.g. H2O2, O3– )

Macromolecular interactions Genetic material (DNA, RNA) Protein machinery (enzymes, polypeptides)

Macromolecular interactions Genetic material (DNA, RNA) Protein machinery (enzymes, polypeptides) Lipids

Cytotoxic consequences • Strand breakage, cross binding mutations and increased cancer risks • Enzyme inhibition, denaturation altered metabolism and protein structure

Cytotoxic consequences • Nucleic acid peroxidation and increased cancer risks

mutation

• GSA depletion reduced detoxication and oxidatives stress • Lipid peroxidates damage

membrane

Figure 4.5: Biologic interactions of reactive metabolites with nucleophilic moieties

and their consequences.

4.4.1 Modes of action and biological interactions of CS The biochemical interactions and potential mechanisms of CS-induced cellular injury are associated with the alkylating and cyanogenic properties of CS. CS is a putative SN2 alkylating agent (Cucinell et al., 1971; Ballantyne and Swanston, 1978), and CS is a cyanogenic substance owing to its metabolic conversion to cyanide (Jones and Israel, 1970). The metabolism and selective toxicity related to the cyanogenic properties of CS is discussed initially followed by discussions pertaining to the alkylating properties of CS. The cyanogenic properties of CS has been investigated since Patai and Rappoport (1962) demonstrated the hydrolysis of CS to malononitrile, the latter having been reported to undergo conversion to cyanide in animal tissues (Nash et al., 1950; Stern et al., 1952). The conversion of CS to cyanide with malononitrile as an intermediate led Jones and Israel (1970) to postulate that some of the toxic actions attributable to CS may arise from the in vivo conversion of CS to cyanide. It is understandable that considerable interest had evolved concerning the cyanogenic properties of CS since cyanide is an extremely potent toxicant. Cyanide binds readily with cytochrome c oxidase resulting in marked perturbation in cellular respiration. Cyanide is a strong nucelophile with multiple effects including the release of secondary transmitters, inhibition of antioxidant enzymes in the brain, and release of catecholamines from adrenergic nerves. The many actions of cyanide, whether secondary to or independent of cytochrome oxidase inhibition contribute to cyanide toxicity – the central nervous system being the primary target for cyanide toxicity in humans and animals. The impairment of cellular oxygen utilization via the inhibition of cytrochrome oxidase leading to altered cellular electron transport resulting in cytotoxic hypoxia is generally accepted as the mechanism-of-action of cyanide (Rieders, 1971; Van Buuren et al., 1972). However, a single biochemical lesion (i.e. inhibition of cytochrome oxidase) may not account for the spectrum of toxic effects associated with cyanide. Way (1984) has suggested that our understanding of the


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mechanistic aspects of cyanide-induced toxicity proceed beyond cytrochrome oxidase inhibition to also encompass the following biochemical interactions and modes of action: (1) lipid peroxidation ( Johnson et al., 1987; Ardelt et al., l989), (2) disruption of neuronal calcium levels/regulation ( Johnson et al., l986); (3) phospholipid hydrolysis (Sakaida and Farber, 1990); and (4) cyanide release of endogenous opioids which may cause respiratory paralysis (Leung et al., 1986; Tadic et al., 1989). In addition to binding with cytochrome c oxidase, cyanide binds with catalase, peroxidase, phosphatase, tyrosinase, xanthine oxidase, and succinic dehydrogenase – these reactions may also contribute to the toxicity associated with cyanide exposure. However, despite the many other biochemical interactions of cyanide, the extremely low concentration of cyanide required to inhibit cytochrome oxidase, the rapid interaction of cyanide with the enzyme, and the key role of cytochrome c oxidase in aerobic metabolism combine to make cyanide inhibition of cytochrome c oxidase the key molecular target in cyanide poisoning. Studies to ascertain urinary and blood levels of cyanide and thiocyanate in workers exposed to low-levels of cyanide were carried out by Maehly and Swensson (1970). Pertaining to the cyanogenic properties of CS, Frankenberg and Sorbo (1973) conducted studies in animals to determine blood cyanide levels and thiocyanate excretion as well as defining the relationship between cyanide levels and symptomatology. They determined blood cyanide levels and thiocyanate excretion in mice after intraperitoneal administration and inhalation exposure to CS. Mice were exposed to a CS aerosol dosage of 20,000 mg-min/m3 which corresponded to about one half of the LD50 for CS. This dosage resulted in rapidly attained high levels of blood cyanide, with peak levels 4–16 min after exposure. Equitoxic doses of malononitrile and cyanide were also evaluated for generating blood cyanide. Based in part on xenobiotic interactions with sulfhydryl groups (Gwynn and Salaman, 1953) and findings of Mackworth (1948) and Dixon (1948) on the inhibitory effect of various lacrimatory compounds on thiol enzymes, Lovre and Cucinell (1970) and Cucinell et al. (1971) studied the effects of the riot control agents CN and CR on SHdependent enzyme systems. Lovre and Cucinell (1970) also postulated that SH-containg enzymes (e.g. lactic dehydrogenase, glutamic dehydrogenase, and pyruvic decarboxylase) are alkylated by CS. Ballantyne and Swanston (1978) have also reported that both CS and CN are SN2 alkylating agents – indicating that they react directly with nucleophilic sites. Findings by Cucinell et al. (1971) suggest that lactic dehydrogenase (LDH) is inhibited by CS, and enzyme inhibition via CS was partially reversed by the addition of excess glutathione (GSH) – indicating the involvement of thiol groups. These findings led Cucinell et al. (1971) to suggest that alkylation of nucleophilic sites, including SH-containing enzymes, is the underlying biochemical lesion responsible for CS-induced toxicity. CS is known to react with the SH groups of dihydrolipoic acid, the disulfhydryl form of lipoic acid, which is a coenzyme in the pyruvate decarboxylase system. Alteration of dihydrolipoic acid biochemistry may lead to decreased acetyl CoA levels resulting in perturbation of cellular bioenergetics. The biochemical interactions and potential mechanisms of cellular injury involving CS are summarized in Table 4.3. Owing to the alkylating properties of CS, with the potential to disrupt regulatory proteins associated with cell cycle control, studies have been conducted to assess the potential of CS to cause cell cycle disturbances. Weller et al. (1995) studied potential cell cycle disturbances induced by CS in proliferating mammalian cells. In these studies, bromodeoxyuridine/Hoechst flow cytometry (Rabinovitch et al., 1988; Kubbies, 1992; Ormerod and Kubbies, 1992) was utilized to analyze the interference of CS with the cell cycle dynamics of synchronous and asynchronous cell systems. Cellular systems employed consisted of Chinese hamster embryo (CHE) and human amniotic fluid-derived fibroblastlike (AFFL) cells. Findings from these studies indicated that CS treatment resulted in



TABLE 4.3 Biochemical interactions of CS and potentially adverse consequences Biochemical constituent/ system affected

Interaction with biochemical component

Result

Adverse/toxicologic consequences

GSH peroxidase

Alkylation

GSH depletion

GSH S-transferase

Alkylation

GSH depletion

Cysteine transporta Lactic dehydrogenase Dihydrolipoic acid

Alkylation Alkylation

GSH depletion Inactivation

Alkylation

Lipoic acidb depletion

Various protein targets

Alkylation

Inactivation

Nucleic acids

Alkylation

Inactivation

Hydroperoxide build-up leading to metabolic dysfunction and oxidative damage (e.g. lipidperoxidation resulting in functional impairment of mitochondria; nucleic acid oxidation leading to mutations; and hemoglobin oxidation resulting in diminished oxygen transport). Decreased detoxification and elimination of harmful electrophilic metabolites via the mercapturic acid pathway. Altered protein synthesis. Perturbed glycolysis and altered bioenergetics. Decreased acetyl CoA levels resulting in perturbed cell bioenergetics and decreased lipogenesis. Modified protein structure, nonspecific cytotoxicity, and cell death. Mutations and alteration of genetic integrity.

Notes a GSH serves as a transport form of cysteine. b Dihydrolipoic acid, which is the disulfhydryl form of lipoic acid, a coenzyme in the pyruvate decarboxylase system.

permanent arrest in the G0/G1 phase in synchronized (G0/G1 phase) CHE cells. In synchronously growing CHE cells, CS treatment resulted in cell kinetic perturbations, which varied with the cell stage during treatment. Human asynchronous AFFL cells exhibited marked cell cycle perturbations on treatment with CS – the effects were induced at CS concentrations below levels that elicited cell cycle alterations in CHE cells. Weller et al. postulated that the induced cell cycle perturbations may have been the result of the interactions of CS with cell cycle regulatory proteins that are involved in traversing the transition point in the late G1 phase, in DNA replication, and/or spindle formation. They further asserted that the inhibition of such regulatory mechanisms by CS may differ among various cellular systems. Lastly, regarding the mechanism(s) of action of CS, it is also theorized that the irritant and painful effect of CS may be due to bradykinin release (McNamara et al., 1969; Cucinell et al., 1971).

4.4.2 Mechanisms and interactions of CR and CN Husain et al. (1991) studied the effects of dibenz CR and CN aerosols on clinical chemistry parameters (e.g. plasma glutamic oxaloacetic tansaminase (GOT), plasma


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glutamic pyruvic transaminase (GPT), acid phosphatase, and alkaline phosphatase). Rats were exposed via inhalation to aerosols of CR or CN. Animals exposed to CR aerosol exhibited no significant changes in plasma GOT and GPT activities as well as in acid and alkaline phosphatase activities. In contrast, CN-exposed animals manifested significant increases in GOT, GPT, acid phosphatase, and alkaline phosphatase activities. Conclusions drawn from the study was that exposure to CN aerosol could lead to tissue damage.

4.4.3 Mechanisms and interactions of capsaicin and capsaicinoids Studies on the mechanisms/modes of action of capsaicin and its analogs have been the subject of many review papers and numerous research publications (Lembeck, 1983; Marsh et al., 1987; Wood et al., 1988; Bevan and Szolcsanyi, 1990; Winter et al., 1990). One of the initial aspects to be addressed was whether a single mechanism of neurotoxicity can account for the capsaicin-induced degeneration observed in the diverse population of capsaicin-sensitive neurons, either central or peripheral. It is now well accepted that the specific action of capsaicin on a subpopulation of neuropeptide-containing afferent neurons involves the activation of a specific receptor (“the vanilloid” receptor) that recognizes capsaicin/capsaicin-like compounds (Szallasi and Blumberg, 1990a,b, 1992; Szallasi et al., 1991). Stucture–activity studies have demonstrated a requirement for both the vanilloid ring and acyl chain moieties for pharmacologic activity (Szallasi and Blumberg, 1999; Caterina and Julius, 2001). The capsaicin-sensitive “vanilloid” receptor has been characterized (Caterina et al., 1997; Hayes et al., 2000); moreover, a number of vanilloid receptor-like proteins have also been identified (Caterina et al., 1999; Schumacher et al., 2000; Delany et al., 2001). Recently, a new nomenclature has been suggested for the superfamily of transient receptor potential (TRP) cation channels (Montell et al., 2002). Based on this nomenclature, the capsaicin receptor (vanilloid receptor type-1, VR1) is renamed TRPV1. Scientists are gaining increased understanding of the molecular basis for the diverse physiological actions produced by capsaicin and other TRPV1 agonists (Gunthorpe et al., 2002). In essence, the activation of the “vanilloid” receptor leads to the opening of a particular type of receptor-operated cation channel, and the ionic mechanism has been elucidated (Marsh et al., 1987; Wood et al., 1988). The influx of Ca and Na leads to depolarization triggering local release of neuropeptides, central protective reflexes as well as autonomic motor responses (Lundblad and Lundberg, 1984; Martling, 1987; Stjarne, 1991). A transient excitation of primary afferents, followed by a more prolonged condition of refractoriness, whereby the primary afferents become unresponsive to further application of capsaicin/capsaicinlike agents or simply stated the densensitization of the primary afferent neuron. According to Jancso et al. (1984), the influx of Ca and Na may lead to rapid cellular damage and eventual cell death by osmosis and calcium-dependent proteases. When capsaicin is administered s.c. at 50 mg/kg to neonatal rats, upwards of 50% of the dorsal root ganglion (DRG) neurons are rapidly destroyed ( Jancso et al., 1977; Fitzgerald, 1983). The acute biological effects of capsaicin are due to the release of bioactive substances such as substance P, calcitonin gene-related peptide (CGRP), and neurokinin A from sensory nerves. These neuropeptides, considered as useful biochemical and histochemical markers, play a role in the communication of primary sensory neurons with other neural and non-neural cells (Salt and Hill, 1983). Release of various neuropeptides by capsaicin produces an altered neurophysiology of sensory neurons in the airway mucosa



as well as neuro-mediated inflammation of the respiratory epithelium, of airway blood vessels, of glands, and smooth muscle. These consequences lead to adverse effects such as bronchoconstriction, edema of the tracheobronchial mucosa, enhanced vascular permeability, enhanced mucous secretion, and neutrophil chemotaxis (Lundberg and Saria, l982a,b; Lundberg et al., 1983a,b, 1984; Hua et al., 1984; Saria et al., 1985; Theodorsson-Norheim et al., 1985; Helme et al., 1987; Tominack and Spyker, 1987; Umeno et al., 1990; Blanc et al., 1991; McDonald, 1992). The modes of action (e.g. the release of neuropeptides, substance P, neurokinin A, involvement of CGRP, and the induction of ion fluxes in neurons) that underlie the pharmacologic actions of capsaicin were elucidated in part in the 1970s and 1980s (Nilsson et al., 1977; Jessell et al., l978; Theriault et al., 1979; Virus and Gebhart, l979; Miller et al., l982; Gamse and Saria, 1983; Lundberg et al., l983a; Burks et al., 1985; Hua et al., l986; Bevan et al., 1987; Franco-Cereceda et al., 1987; Holzer l988; Lou et al., 1992; Maggi, 1993). A number of these responses; for example, bronchoconstriction, vasodilatation, and protein extravasation are mediated by substance P, which belongs to a group of biologically active peptides referred to as tachykinins. Substance P is one of the more thoroughly studied of these putative neurotransmitters, and the reader is referred to papers on substance P by Stern (1963), Leeman and Mroz (1974), Hokfelt et al. (1975), and Lembeck and Gamse (1982). Substance P has been researched from the 1930s (Chang and Gaddum, 1933) since its original discovery by von Euler and Gaddum (1931). The isolation and biochemical characterization of substance P was accomplished by Chang and Leeman (1970) and subsequently sequenced by Chang and colleagues (Chang et al., 1971). Substance P is postulated to have a neurotransmitter role in primary sensory neurons for central transmission of afferent information (Lembeck, 1953; Otsuka Konishi, 1983) and as a peripheral mediator of neurogenic inflammation and smooth muscle contraction (Lembeck and Holzer, 1979; Lembeck and Gamse, 1982). Capsaicin-induced effects, namely, bronchoconstriction, vasodilatation, and plasma extravasation are mimicked by substance P and/or inhibited by SP antagonists; however, other physiological actions of capsaicin such as the chronotropic and inotropic effects on the heart are not mediated via substance P. As previously mentioned, capsaicin has been shown to release substance P, which can produce bronchoconstriction directly by activation of specific receptors or by release of histamine and other mediators. In addition, capsaicin may cause reflex bronchoconstriction by stimulating c-fibers in both pulmonary and bronchial circulation. Thus, the possibility that bronchoconstriction could be secondary to substance P release or to a vagal reflex. Aside from the modes of action of capsaicin and capsaicinoids on sensory neurons, these substances manifest chemoprotective properties against the genotoxic effects of known carcinogens as well as exhibiting antioxidant activity. Capsaicin is one of several dietary phytochemicals with potential chemopreventive activity. For a review of this subject area, the reader is referred to papers by Surh and Lee (1995) and Surh et al. (1998). The chemoprotective properties against mutagenesis and tumorigenesis by known carcinogens stems from the inhibitory action of capsaicin on microsomal monoxygenases involved in carcinogen activation. Capsaicin and its analog, dihydrocapsaicin, have been demonstrated to inactivate cytochrome P-450 HE1 and other isoforms (i.e. P-450 1A2) of the cytochrome P-450 family (Surh et al., 1995b; Teel et al., 1997). For a more detailed discussion on the interaction of dietary substances on microsomal monoxygenases, the reader is referred to an excellent overview on the effects of dietary constituents on cytochrome P-450 enzymes by Guengerich (1995). Capsaicin has been shown to attenuate the mutagenicity of vinyl carbamate (VC) and N-nitrosodimethyl-amine (NDMA) as assessed in Salmonella typhimurium (Surh et al., 1995b). They noted that suppression of NDMA and VC-mediated mutagenicity by capsaicin correlated with their inhibition of P-450-mediated metabolism, namely, N-demethylation and p-nitro-phenyl hydroxylation. The antimutagenicity of capsaicin was also studied by Azizan and Blevins (1995).


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Studies by Surh and coworkers (Surh et al., 1995b) revealed a substantial anticarcinogenic effect of capsaicin, suggesting that capsaicin and capsaicinoids possess chemoprotective activity. They demonstrated that the pretreatment of female ICR mice with capsaicin decreased the average number of VC-induced skin tumors by 62% at 22 weeks after promotion. Various constituents in pepper plants (i.e. Capsicum annuum) and various pungent constituents present in ginger and other zingiberaceous plants have potent antioxidant effects. Lee et al. (1995) studied the antioxidant activity of major pepper flavonoids (i.e. luteolin, quercetin). Luteolin had the highest antioxidant activity – capsaicin also exhibited antioxidant activity. Thus far, discussions have centered on the mechanisms that underlie the neuropharmacologic and neurotoxic actions of capsaicin and capsaicinoids as well as the chemoprotective properties of capsaicin. Subsequent discussion on the mechanisms/modes of action continues with a focus on the toxic metabolites of capsaicin and their biological interactions. In their review on the metabolism and toxicity of capsaicin, Surh and Lee (1995) have discussed the role of metabolic activation in capsaicin-induced toxicity, and the metabolic pathways involved in the bioconversion of capsaicin to electrophilic metabolites and other reactive moieties, namely, quinone, ring epoxide, and phenoxy radical. As indicated, metabolic activation of capsaicin to reactive intermediates via the hepatic cytochrome P-450 system includes the conversion to semiquinone and quinone derivatives. Quinones is a general term for a class of compounds that are endogenous biochemicals, are found in natural products, or are generated via metabolism of xenobiotics. The bioconversion to the quinone derivative is discussed in some detail, since this particular pathway serves to illustrate the importance of metabolic activation in determining the toxicological profile of a chemical as well as the significance of these metabolic products in the etiology of cellular and physiological perturbations and toxicologic consequences. The quinone intermediate of capsaicin can be formed by either of the following metabolic pathways: (1) initial Odemethylation of the 3-methoxy group on the vanillyl ring with concomitant oxidation to the semiquinone or o-quinone derivatives or (2) O-demethylation of the phenoxy radical intermediate of capsaicin. Quinone derivatives of xenobiotics produce toxic effects in vivo including cytotoxicity, carcinogenicity, and immunotoxicity. Cellular damage can occur via alkylation of critical cellular proteins and/or DNA. In addition, it should be noted that redox cycling of quinones generate adducts and the formation of ROS. Production of reactive oxygen moieties can lead to severe oxidative stress in cells via the formation of oxidized cellular macromolecules. In general, these moieties can interact with nucleophilic sites of macromolecules such as proteins, DNA, and RNA – these interactions are thought to be critical in the etiology of capsaicin-induced cytotoxicity, mutagenicity, and carcinogenicity. The formation of a quinone type intermediate following metabolism of capsaicin is of great interest owing to the multiplicity of quinone-mediated effects that include alkylation of DNA and proteins, GSH depletion, ROS formation, and ROS-related effects such as DNA oxidation and lipid peroxidation. Quinones, as previously indicated, are activated metabolites of polycyclic aromatic hydrocarbons, and represent a class of reactive intermediates that produce a number of deleterious effects including cytotoxicity, immunotoxicity, and carcinogenesis. The mechanisms by which quinones produce these effects can be via alkylation of proteins and or DNA or by the formation of ROS that are generated by the redox cycling of quinones. Quinones can react with nucleophilic amino groups of DNA and proteins. Additionally, quinones react with sulfur nucleophiles (i.e. GSH and cysteine residues of proteins) leading to protein alkylation and/or GSH depletion. The generation of ROS leads to severe oxidative stress in cells via the formation of oxidized cellular macromolecules (e.g. DNA, proteins, and lipids) as well as activation of signaling pathways involved



in the initiation, promotion, and progression of carcinogenesis. For more in-depth discussion on the subject of quinone chemistry and toxicology the reader is referred to Monks et al. (1992) and Bolton et al. (2000). As discussed, capsaicin may be metabolized to a quinone, which is an activated metabolite having a multiplicity of deleterious effects on cellular biochemistry and physiology. ROS formation and ROS-mediated lipid peroxidation are quinonemediated effects. The following is a brief discussion concerning lipid peroxidation and its consequences. Lipid peroxidation, which is associated with numerous pathological processes (Del Maestro, 1980; Recknagel et al., 1982), has been the focus of considerable research, with studies on the mechanism of formation of peroxide radicals and their role in the pathogenesis of various diseases. Timbrell (1982) has categorized the consequences of lipid peroxidation as secondary disturbances (e.g. membrane damage, enzyme inactivation) and tertiary disturbances (e.g. increased capillary permeability, protein crosslinking, reaction with SH, and decreased DNA synthesis). Peroxidation involves polyunsaturated fatty acids giving rise to free radicals and endogenous peroxides possessing high reactivity and cytotoxic properties. Lipid peroxidation is a reaction between fatty acids and oxygen, initiated by radical intermediates and active oxygen species, produced by metabolic processes or from metabolic conversion of xenobiotics. Lipid peroxidation is a process that may generate a broad range of lipid peroxidation products (Sevenian and Hochstein, 1985). Oxygen-derived free radicals are continuously produced in the cell during cellular metabolism as well as during the redox cycle of biochemical substances and antioxidant defense mechanisms are in place to minimize the harmful effects of these moieties. Free radicals are self-generating in a chain reaction and may be harmful to cells if protective mechanisms (e.g. -tocopherol ascorbic acid, glutathione, antioxidant enzymes such as catalase, and glutathione-related enzymes such as GSG-PX) are overloaded or not active (McCord and Fridovich, 1978). A discussion on the reactive intermediates generated as a result of capsaicin bioconversion is incomplete without discussion on the formation of methyl radicals. O-demethylation of the 3-methoxy group on the vanillyl ring or O-demethylation of the phenoxy radical may generate the highly reactive methyl radical. O-demethylation generates the extremely reactive methyl radical, which is well known to alkylate nucleic acids and proteins. The alkylation of proteins and/or GSH by electrophilic metabolites of capsaicin have consequences affecting cellular energetics, detoxification processes, as well as other biochemical processes. The potential of covalent binding with microsomal protein; for example, may account for the impact of capsaicin on xenobiotic metabolizing enzymes and liver toxicity. The interaction of methyl radicals are not limited to proteins and nucleic acids, these highly reactive moieties can also cause peroxidation of polyunsaturated and saturated lipids – the consequences of which have been previously discussed. In addition to the potential adverse effects resulting from the direct interactions of cellular constituents with the metabolic products of capsaicin, deleterious effects may result as a direct action of capsaicin on cellular processes, namely, cell bioenergetics. Concerning mitochondrial energy metabolism, Yagi (1990) postulated that capsaicin and dihydrocapsaicin produce repression of NADH-quinone oxidoreductase activity, which confirms findings suggesting capsaicin-induced inhibitory effects on hepatic mitochondrial bioenergetics.

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DISCLAIMER NOTICE The opinions or assertions contained herein are those of the author and are not to be construed as official or as reflecting the views of the Army or the Department of Defense.


CHAPTER

Riot Control Agents and Acute Sensory Irritation

5

EUGENE J. OLAJOS1 AND WOODHALL STOPFORD2 1 US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 2

Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, North Carolina

5.1 INTRODUCTION Riot control agents (RCA) are highly potent peripheral sensory irritants (PSI) that elicit “irritative” or “noxious” sensation due to action on the sensory nervous system of the eyes, the respiratory tract, and the skin. PS irritants are chemicals of widely differing structure, which interact nonspecifically with sensory nerve receptors associated with these target organs. Large differences appear in the sensory irritation potency among chemicals; for example, toluene diisocyanate (0.1 ppm) produces a 25 percent decrease in respiratory rate versus a comparable decrease produced by 1,000 ppm of isobutyl alcohol (De Ceaurriz et al., 1981). The RCAs are among the most potent PSI substances known comparable to highly potent PSI irritants such as N-(4-hydroxy-3-methoxyphenyl)2-chlordecanamide (plethysmography RD50 values: 3.4 107 M and 2.1 107 M, chloroacetophenone and N-(4-hydroxy-3-methoxyphenyl)-2-chlorodecanamide, respectively) (Ballantyne, 1999). A model to explain the mode-of-action of sensory irritants was initially proposed by Alarie (1973) and further elaborated by Nielsen and Alarie (1982) and Nielsen (1991). The model is based on the chemical and physical interactions of sensory irritants with a receptor protein in a lipid bilayer. It is postulated that the receptor protein contains multiple sites of interaction. One site containing a disulfide bond that can either be chemically broken or interacts non-covalently with PS irritants, and the other site comprising a nucleophilic moiety (e.g. SH, NH, OH) that can interact chemically with irritant molecules. Interaction with sensory nerve receptors produces discomfort and/or pain at the site of contact along with related reflexes. The effects on exposure to PS irritants disappear within a short time following cessation of exposure. The major characteristics of PS irritants are as follows: (1) their actions are localized (e.g. mucosae, skin), (2) they produce local discomfort and/or pain with locally mediated reflexes, and (3) they may elicit associated systemic reflexes (Figure 5.1). Although PSI effects predominantly involve the eyes and the respiratory tract, involvement of the skin may also occur particularly at higher amounts/concentrations of material. It should be noted that peripheral sensory irritation is a pharmacological effect to be distinguished from a toxicological response. However, most substances producing a PSI effect will usually also produce toxic effect(s) (i.e. inflammation) upon exposure to high concentrations and/or extended exposure periods. Pharmacological actions of PSI substances on the eyes include: copious lacrimation, blepharospasm (uncontrollable closure of the eyelids), itching, burning sensation, and discomfort or pain. Respiratory system effects following exposure to PSI


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Peripheral sensory irritants

Sensory nerve receptor (i.e. skin)

Central nervous system

Local sensations

Afferent neuron

Dorsal root ganglion

Reflexes Efferent neuron

Spinal cord

Figure 5.1: Peripheral sensory irritants and locally mediated reflexes.

substances comprise the following responses: decreased breathing rate, increased secretions, coughing, sneezing, burning sensation of the upper and lower respiratory tract, constricting sensations in the chest, and discomfort or pain of the throat, nasopharynx, and nose. The clinical presentation varies somewhat depending on the degree of exposure, the chemical nature of the material, and the site of exposure. Skin effects on exposure to peripheral sensory irritants are generally limited to the production of transient erythema, which occur at exposure levels considerably greater than those concentrations resulting in ocular or respiratory effects. High concentrations of RCAs such as CS and CN can also cause edema and blistering. As mentioned, PSI substances produce local discomfort and/or pain with locally mediated reflexes. Local reflexes resulting from exposure to PS irritants are important protective mechanisms limiting further exposure and uptake (e.g. lacrimation which aids in the dilution and removal of material from the eye; decreased breathing rate which limits the systemic uptake of xenobiotic). Additionally, PS irritants are also associated with tachyphylaxis – decreasing responses that follow consecutive applications of test substance (see also Chapter 12). There are numerous factors that influence the response of individuals to sensory irritants. A variety of physical and biological (physiological and behavioral) factors may influence the amount of PS irritant required to elicit sensory irritation as well as the onset and duration of effects. Physical factors include amount/concentration, particle size, vehicle, temperature and humidity, and environmental conditions. The particle size of aerosols may profoundly affect irritant response; for example, small particles, that is, ~2 cause ocular and respiratory irritation, whereas larger particles ~50 produce predominantly ocular irritation with sustained action (Owens and Punte, 1963). Biological factors


RCA AND ACUTE SENSORY IRRITATION


that may influence the response to PSI substances include health and nutritional status, tolerance, personality, physical activity, and motivation. Bioassays varying in sophistication and sensitivity have been developed to assess the PSI potential and comparative potency of different sensory irritants. Some of these methods are as follows: (1) frog flexor reflex (Feniak, 1966), (2) blepharospasm test (Ballantyne and Swanston, 1973; Bar-Ilan, 1997), (3) neurophysiological preparations (Green and Tregear, 1964; Dirnhuber et al., 1965; Kulle and Cooper, 1975; Foster and Ramage, 1981; Tsubone and Kawahl, 1991), and (4) measures of decreased respiratory frequency (i.e. mouse plethysmograph test) (Alarie, 1966, 1981a). The various neurophysiological bioassays have found use in the assessment of PSI substances such as formaldehyde and other industrial chemicals; however, they have not been widely utilized in the assessment of RCAs. RCAs have been evaluated for PS irritancy mainly via human testing and by the blepharospasm and mouse plethysmograph tests, which are discussed in greater detail in the next paragraph. The blepharospasm test, whose origins may be attributed to early studies on capsaicin (Porszasz and Jancso, 1959), is frequently used to assess the potential of a substance to produce sensory irritation of the eye in both animals and human subjects. This assay has been used to determine threshold concentrations for irritation and to ascertain the relative potencies of different PS irritants. Moreover, the guinea pig blepharospasm test has been used successfully as a screening procedure in the development of ophthalmic drug preparations (Bar-Ilan, 1997). The blepharospasm test involves the application of increasing amounts of test article to the surface of the cornea or on sequential exposure to increasing levels of aerosolized test article. The proportion of the population, which develops blepharospasm, is recorded and a dose–response relationship is obtained. It is a relatively simple bioassay, which provides reproducible threshold estimates for irritancy of compounds administered topically or as aerosolized material. It is easier to perform than other bioassays of irritancy (e.g. frog flexor reflex test, guinea pig ileum), and different species of animals can be utilized. In humans, assessment of threshold irritancy can be undertaken with minimal discomfort, and having the advantage that objective as well as subjective responses can be measured on exposure to an irritant substance. Of further note relevant to species sensitivity, the human eye is more sensitive to PS irritants than the eyes of common laboratory animals. Based on studies by Ballantyne and Swanston (1973), the human eye is about 7 times more sensitive than the eye of the guinea pig and about 20 times more sensitive than the rabbit eye. The respiratory system is also sensitive to the irritant action of chemicals, and techniques to evaluate the irritant properties of various substances based on reflex-induced alterations of the respiratory pattern following exposure to airborne materials have been developed since the 1950s. In particular, altered breathing, a quantitatively measurable endpoint, that is used to quantify sensory irritation following exposure to an irritant. Methodology, based on the respiratory rate, as the criterion of response, has been developed by Alarie to evaluate acute airborne sensory irritation (Alarie, 1966). This technique represented an improvement upon previous approaches that depended on measures of airway resistance (Amdur and Mead, 1955, 1958). The plethysmographic technique detects a decrease in respiratory rate during exposure to sensory irritants. The model is based on data indicating that sensory irritation of the upper respiratory tract is accompanied by a reflex pause in the expiratory phase of respiration, which gives rise to a marked reduction in respiratory frequency. Dose–response relationships can be derived, and the RD50, which is the concentration necessary to produce a 50 percent decrease in respiratory rate, is determined (Alarie, 1981b). It has been demonstrated for a substantial number of chemicals, that the decrease in respiratory rate in mice is highly correlated to subjective reports of sensory irritation in humans (i.e. complaints of eye, nose and throat irritation) (Alarie, 1966; Alarie, 1973; Kane et al., 1979). Thus, the plethysmographic

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technique has been used to compare the irritancy potency of various sensory irritants, for the quantitative prediction of sensory irritation in humans, and to predict acceptable levels of exposure in industrial environments. The mouse plethysmograph test has been used to evaluate the irritant potential of RCAs. The technique relies on head-only exposure to varying concentrations of test article and measurement of the breathing rate with a body plethysmograph. Species differences in sensitivity exist and the mouse is the species of choice to assess irritancy potential. Although animal studies provide critical data in the evaluation of peripheral sensory irritant substances and provide the framework for additional testing in human subjects, it is nevertheless highly desirable to assess the effects of PSI substances in human subjects. Compelling reasons for using human subjects in testing peripheral sensory irritants are as follows: (1) Studies using human subjects allow for the assessment of subjective endpoints such as discomfort or pain, which is an important component in the evaluation of these materials in humans. (2) Differences in sensitivity between animal models and humans to PS irritants – reliance on animal data alone may lead to an underestimation of the potency and/or potential hazards associated with a particular substance. (3) Human studies allow for more quantitative assessment and determination of variability than obtainable with animal models. Understandably, studies in human subjects would be conducted only when adequate toxicological information exist on the test material to ensure that the testing in human subjects carries little or no risk.

5.2 OCULAR SENSORY IRRITATION AND RCAS The eyes are among the most readily accessible organs in terms of their location. The eyes are highly sensitive to obnoxious and irritant materials as well as a portal of entry for various foreign substances. Many chemicals possess more-or-less lacrimatory properties ranging in irritancy from mild to very severe. RCAs cause intense lacrimation and pain produced by the direct action of the chemical on ocular tissues. An additional outcome of sensory irritation of the eye is a transient increase in intraocular pressure. This response has been demonstrated following exposure to splash contamination of the eyes as well as following exposure to aerosols of PS irritants (Ballantyne et al., 1976). The etiology of the increased intraocular pressure is unknown in most cases, but changes in regional blood flow may be a causal factor. The eyes are provided with barriers (i.e. tear film) and protective mechanisms (i.e. blinking, reflex tearing) to protect the eyes from the effects as well as entry of foreign substances. Tearing and the blinking actions are highly effective in rapidly diluting and/or removal of foreign substances from the ocular surface. Reflex tearing increases the flow rate, which promotes faster elimination of the irritant from the eye. Additionally, the numerous proteins present in tear fluid may bind to and even metabolize foreign substances thus rendering them unavailable or inactive. However, highly potent PS irritants such as RCAs can overwhelm the barriers and protective mechanisms of the eye – hence their use as harassing agents to quell individuals during civil disturbances and in subduing an individual in certain situations requiring law enforcement intervention. RCAs primarily act on the eyes, which is the most sensitive target organ to these compounds. The action of RCAs on the eye has essentially two components, one a lacrimogenic, reversible, and essentially non-injurious effect; the other an injurious effect(s) (i.e. corneal edema, corneal ulceration and scarring), which is associated with high concentrations and/or prolonged exposure to these substances. The most characteristic property of RCAs is their ability to produce an intense and immediate stinging sensation in the eyes with tearing at low concentrations, which results in a temporary disabling. Low levels of RCAs produce reversible and non-injurious effects; however, at high concentrations ocular injury is



produced. The injurious effects of RCAs involving the eyes is covered in the Chapter 6, which deals with the toxicology of these compounds. Several ocular irritancy studies on riot control agents CS, CR, and CNS (a CN variant) have been conducted in various animal species (Leopold and Lieberman, 1971; Gaskins et al., 1972; Ballantyne and Swanston, 1973, 1974; Ballantyne et al., 1974; Rengstorff et al., 1975). Ocular irritancy data and human toxicity estimates for the common RCAs are highlighted in Table 5.1 along with comparative ocular irritancy data for various lacrimatory compounds. Ocular effects characteristic of PS irritants and associated with exposure to low levels of RCAs are described in greater detail for each of the main RCAs.

5.2.1 Chlorobenzylidene malononitrile (CS) Chlorobenzylidene malononitrile produces harassing effects at concentrations very much less than amounts likely to result in adverse effects. CS produces harassment by its sensory irritant effects principally on the eyes (e.g. excessive tearing, blepharospasm, and discomfort).

5.2.2 Dibenz[b,f]1:4-oxazepine (CR) The occurrence of intense lacrimation and skin irritation on exposure to dibenz[b,f]1:4-oxazepine was initially reported by Higginbottom and Suschitzky (1962). Systematic

TABLE 5.1 Ocular irritancy thresholds and toxicity estimates for human responses to RCAs and various lacrimogenic compounds Compound

Riot control agents CS CR CN OC Lacrimogenic agents Acrolein Benzyl bromide Bromobenzyl cyanide Chloroacetone Chloropicrin DM Xylyl bromide

Ocular irritancy

Rate of action

Irritancya threshold (mg/m3)

Intolerablea conc. (mg/m3)

Lethalb conc. (mg/m3)

Profound Profound Profound Profound

Instantaneous Instantaneous Instantaneous Instantaneous

0.004 0.002 0.3 (—)

5 1 35 (—)

2,500c 10,000c 850c (—)

High High High High High High High

Rapid Rapid Rapid Rapid Rapid Rapid Rapid

2–7 4 0.15 18 2–9 ~1 ~5

50 50 0.8 100 50 5 15

350 4,500 350 2,300 2,000 650 5,600

Notes References (Prentiss, 1937; Jacobs, 1942; Sartori, 1943; Cookson and Nottingham, 1969; Ballantyne, 1977a; Beswick, 1983; NAS, 1984; Hu, 1992; Sidell, 1997; Maynard, 1999). a A range is given when more than one value has been reported. b Estimate for minimal lethal concentration (10 min exposure). c Values derived from the human LCt50 estimate (lower bound) divided by 10 min to obtain the lethal concentration in mg/m3. LCt50 values (mg-min/m3) are those reported by Maynard (1999).


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studies into the ocular effects of CR were conducted by Ballantyne and co-workers, Owens et al., and others. Owens et al. (1970); for example, evaluated the ocular effects of 1% CR solutions (CR in glycol or glycol ether) in monkeys and rabbits following single or multiple-dose application. Mild and transitory eye effects, characterized as slight redness and mild chemosis, were observed in the animals after a single application of 1% CR solution. Multiple applications of CR solution to the eyes over a 5-day period resulted in minimal ocular effects. Biskup et al. (1975) also reported the absence of ocular irritation in animals following single or repeated-dose application of 1% CR solution. Studies were conducted by Ballantyne and Swanston (1974) to assess the ocular irritant potential of CR among various animal species and in human subjects. Dilute solutions of CR in saline were applied to the eyes to ascertain the threshold concentration for producing uncontrollable closure of the eyelids (blepharospasm). TC50 values were derived for several animal species (e.g. TC50 7.9 105 M, rabbit; TC50 3.5 105 M, guinea pig). The TC50 to produce sensation on the human eye is 9.1 102 mg/L solution (4.9 107 M), and the median threshold concentration (TC50) to produce blepharospasm for man is 8.6 107 M. These findings indicate the high degree of the ocular irritant potency of CR. Ballantyne and Swanston (1974) also theorized that CR, at a concentration of 3.3 106 M, would be incapacitating based on extrapolation from human eye data on sensation. In general, their findings suggest that the molar concentration required to elicit threshold effects on the human eye is less for CR than for CS. Furthermore, they postulated that a CR concentration of less than 0.25 M (5% solution) would not produce structural damage to the eyes when applied to the conjunctiva. Ballantyne et al. (1973) published findings of a human study on the effects of CR solutions. One phase of the study was to ascertain the effects of highly dilute solutions of CR (0.0025% to 0.001%) on volunteer subjects subjected to whole-body exposures. Following a 15-second individual drench with CR, subjects experienced intense stinging of the eyes, profuse lacrimation, injection of the conjunctivae, and blepharospasm – characteristic responses to PSI substances. The stinging of the eyes was very rapid in onset, occurring within seconds of exposure. Stinging of the skin around the eyes was also noted, which rapidly intensified to a strong burning sensation. Group drenches, 1 min in duration, were also conducted. The ocular responses noted were similar to those observed in the individual 15-s drenches. CR is a highly potent PSI material – compared to CR, effects elicited by CS were of shorter duration, less severe, and more variable. Ballantyne et al. concluded that even very dilute solutions of CR (0.0025% to 0.001%) produced sensory ocular effects. Extensive studies were also conducted on the ocular effects of CR as an aerosol (360–571 mg/m3, 30 min exposure), as a solid (0.1–5 mg), and as a solution (1–10% in polyethylene glycol) (Ballantyne et al., 1975). Measurements of intra-ocular tension and corneal thickness were conducted as well as histological examination of the eyes. CR in solution produced mild to moderate concentration-dependent ocular effects that persisted for several days duration. The ocular effects were transient even at the higher concentrations. Topical application of solid CR resulted in lacrimation and minor irritation of the conjunctivae and eyelids. Mild lacrimation and conjunctival injection were consequences on exposure to CS aerosols – these effects subsided within an hour. In addition, results indicated that CR solutions produced reversible dose-related increases in corneal thickness. Ballantyne et al. (1975) concluded that CR produced considerably less damage to the eye than CN and that there was a much greater degree of safety for CR than CN.

5.2.3 Chloroacetophenone Chloroacetophenone is a highly potent PS irritant and is more likely to cause serious eye effects than either chlorobenzylidene malononitrile or dibenz[b,f ]1:4-oxazepine



(Ballantyne et al., 1975). Exposure to CN elicits immediate effects on the eye to include intense irritation and copious lacrimation. CN-induced ocular irritation signals avoidance and the intense lacrimation and blepharospasm initiate a defense mechanism. The acute sensory irritation, a pharmacological effect, resulting from exposure to low dosages of CN disappear on cessation of exposure. However, at higher exposure concentrations, toxic manifestations involving the eyes occur. Exposure to chloro-acetophenone at concentrations that are generated by a defense spray device usually results in ocular effects that are characteristic of PS irritants. However, concentrations of CN above those usually produced by defense sprays can cause more severe ocular effects including corneal edema, conjunctival sloughing, and keratitis. A description and discussion of CN-induced severe ocular effects are presented in Chapter 6.

5.2.4 Capsaicin, capsaicinoids, and oleoresin capsicum

5.3 PULMONARY SENSORY IRRITATION OF RCAS The sensory system of the respiratory tract, which contains numerous sensory endings, is easily stimulated by a variety of chemicals. Stimulation of these nerve endings is followed by a variety of reflex responses. The pulmonary system has a high sensitivity to PSI substances in particular to capsaicin and RCAs such as CS, CR, and CN. Inhalation of PSI substances produces sensation of irritation and discomfort, which in severe cases leads to pain in the upper and lower respiratory tract. Local reflexes initiated by exposure to


Typical ocular signs and symptoms associated with exposure to aerosols of oleoresin capsicum (OC) consist of lacrimation, conjunctival inflammation, redness, severe burning pain, swelling, and blepharospasm. In humans, exposure to OC spray can also cause loss of the blink reflex. When applied to the eyes, capsaicin – the most important biologically active component of OC – leads to neurogenic inflammation (vasodilatation and extravasation) and unresponsiveness to physical and chemical stimuli. It has been reported that the topical application of capsaicin eliminates the blink reflex for up to 5 days following dosing (Buck and Burks, 1986). According to one study, no permanent ocular damage is observed despite the induction of long-lasting irritation by capsaicin (Archuleta, 1995). However, previous findings reported by Shimizu et al. (1984) have demonstrated the occurrence of trigeminal nerve fiber degeneration in the cornea following the systemic administration of capsaicin. Animal studies have also demonstrated the ability of capsaicin to produce miosis and aqueous flare (Gonzalez et al., 1993). Recent studies have examined the ocular effects of pepper sprays on humans (Vesaluoma et al., 2000; Zollman et al., 2000; Holopainen et al., 2003). Zollman et al. (2000) reported the findings of a study on the short-term ocular effects of “pepper spray” in human volunteers. Individuals were sprayed in the face with a water-based OC formulation (defense spray containing 0.5 million Scoville Heat Units (SHU) or 1 million SHU) at a distance of 1 meter. OC spray was effective in producing ocular pain, blepharospasm, tearing, and blurred vision without causing any short-term sequelae. The symptoms commenced immediately after exposure and gradually subsided over a one-hour period. Visual acuity was unaffected by exposure to OC spray; however, corneal sensation was severely affected on exposure to test article. Corneal erosions were evident in a number of cases as well as conjunctival injection; however, corneal abrasions were not seen, and no exposed individuals required medical intervention. Holopainen et al. (2003) reported that the solvents in pepper sprays may have been responsible for the corneal erosion observed in individuals exposed to pepper spray (also refer to Chapter 7).

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PS irritants include coughing, sneezing, increased secretions, decreased respiratory rate, and decreased tidal volume. The effect of PS irritants on the upper respiratory tract is that of decreased breathing rate via trigeminal nerve stimulation. Characteristic actions of PS irritants of the lower respiratory tract are an increase in breathing rate and tidal volume. However, concentrations to elicit trigeminal nerve stimulation are significantly lower than those producing effects characteristic of lower respiratory tract stimulation – the trigeminal reflex will usually predominate.

5.3.1 Chlorobenzylidene malononitrile (CS) The RCA chlorobenzyl malononitrile was developed in the 1950s as a potent and safe RCA. CS is highly irritating to the mucous membrane of the respiratory tract. The level of irritation on exposure to CS is of such magnitude that it causes an exposed individual to seek escape from the exposure. Animals exposed via inhalation to pyrotechnically generated CS manifest changes in respiratory parameters. Severe lung injury and consequently respiratory failure are the underlying causes of mortality seen in experimental animals following inhalation of CS. The pharmacology and toxicology of CS is discussed in greater detail in Chapter 6.

5.3.2 Dibenz[b,f]1:4-oxazepine (CR) Dibenz[b,f]1:4-oxazepine, a more recent addition to the riot control family of compounds is a highly potent sensory irritant of low toxicity. The irritant effects of CR are more transitory than those of other RCAs. As with the other RCAs, supra-threshold concentrations of CR may lead to deleterious effects (e.g. congestion, hemorrhage, and emphysema) on the pulmonary system (Colgrave et al., 1979).

5.3.3 Chloroacetophenone Chloroacetophenone produces immediate responses involving the respiratory system, namely, respiratory tract irritation, nasal congestion, sneezing, coughing, and a sense of suffocation. The symptoms may persist for up to 20 min following removal from the contaminated atmosphere. As with the other RCAs, high doses of material may lead to injurious action on the pulmonary system (detailed discussions on the toxicity of CN in Chapter 6).

5.3.4 Capsaicin, capsaicinoids, and oleoresin capsicum Capsaicin and OC are extremely potent sensory irritants of the respiratory system. Capsaicin, the principal ingredient of OC, has a multiplicity of effects on the respiratory system. Following capsaicin exposure, there is mucous production in the nose and throat. As little as 0.1 g of capsaicin induces severe coughing (Nichol et al., 1990) and sneezing (Lundblad et al., 1984). Somewhat higher doses result in irritation and a burning sensation in the nasal passages (Philip et al., 1994), and bronchoconstriction is also observed following exposure (Fuller, 1991; Hathaway et al., 1993). Pulmonary symptoms following exposure to OC spray include coughing, shortness of breath, and inflammatory reaction of the airways. Experimental data on airway and pulmonary tissue responses to capsaicin as well as OC have been published (Martins et al., 1993; Busker et al., 2001).



The effects of xenobiotics on sensitive populations are of great interest to toxicologists and public health officials since it is most desirable that health risks incurred by sensitive populations on exposure (occupational or environmental) to xenobiotics are minimized as much as possible. A susceptible population will manifest a different or enhanced response to a foreign substance than will most persons exposed to the same material. Of great interest is the effects of PS irritants on individuals who demonstrate increased sensitivity for inhaled irritants due to compromised respiratory physiology (e.g. asthma and related diseases). Persons with bronchial hyperactivity display increased sensitivity for inhaled irritants. The heightened concern regarding the widespread use of OC spray has drawn attention to the risks and safe use of riot control materials, particularly as related to the higher risks encountered by susceptible populations (i.e. asthmatics). Busker et al. (2001) had addressed the aspect of susceptible individuals (e.g. asthmatics) having conducted a study to ascertain the effects OC (pepper spray, PEPS) in the ovalbuminsensitized guinea pig, which is an animal model of asthma. The guinea pig has been demonstrated to be very sensitive for the effects of capsaicin (Surh and Lee, 1995), and the ovalbumin-sensitized guinea pig has been developed as a model for bronchial hyperresponsiveness (Karol, 1994; Sato et al., 1998). In the studies by Busker and coworkers, the effects of varying concentrations of aerosolized pepper spray to include very high concentrations of test material on healthy and asthmatic animals were evaluated. Findings indicated that brief exposure to relevant amounts of OC spray did not result in significant changes in pulmonary function, and that asthmatic animals were more sensitive to PEPS exposure than the healthy animals.

5.4 DERMAL SENSORY IRRITATION OF RCAS Although the eyes and respiratory tract are the primary organs affected by RCAs, the skin is also often involved. RCAs are irritants, which in low concentrations produce tingling or burning sensation and transient erythema. These localized actions are characteristic of PSI compounds and in part comprise a constellation of effects, that is the base for the use/application of riot control compounds as “harrassing agents.” Application of RCAs (i.e. capsaicin, CR) to human skin produces a burning sensation frequently associated with erythema (Jancso, 1960; Ballantyne et al., 1973). At higher concentrations, RCAs such as CN and CS can cause edema and blistering. In addition, RCAs can produce allergic contact dermatitis after an initial exposure. These aspects, pertaining to the dermatotoxicity of RCAs, are covered in Chapter 6 dealing with the toxicity of these compounds. A detailed discussion on the dermal sensory irritation of CR follows, since this particular RCA illustrates the optimization of peripheral sensory irritation with minimal adverse effects involving secondary sites of action.

5.4.1 Dibenz[b,f]1:4-oxazepine (CR) The effects of CR on the skin are generally limited to the production of transient erythema, and contact with CR does not induce vesication, contact sensitization, or delay the healing of skin injuries (Holland, 1974; Ballantyne, 1977a,b). The burning sensation on exposure to CR persists for 15 to 30 min, and erythema may last for 1–2 h. Considerable interest in the cutaneous effects of sensory irritant compounds has led to several studies on the dermal effects of CR in humans (Weigand and Mershon, 1970; Ballantyne et al., 1973; Holland, 1974). Weigand and Mershon (1970) studied the dermal effects of dilute CR and CS solutions. Test subjects were patch tested on various anatomical sites with concentrations of test article ranging between 0.01 and 1.0%, and exposure


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duration was for 5 or 30 min. Stinging sensation was evident on exposure to both compounds with CR eliciting a response of greater intensity. The onset of stinging was more prompt at higher ambient temperatures. Transient erythema of varying degree was evident, which subsided within 4 h. Holland (1974) evaluated skin reactions to CR in humans after application of varying amounts of CR as a powder or as dry material moistened with saline. Erythema was noted in 10 min, which faded on removal of test article, and when moistened, CR produced marked irritation. No swelling or vesication was evident, even under adverse conditions. It was concluded that CR is capable of producing acute cutaneous discomfort. In comparing the results with similar studies on CS and CN, Holland (1974) concluded that all reactions to CR were mild and transient compared to that of CS, which resulted in an erythema of greater duration, and to that of CN which produced blistering. Ballantyne and coworkers (1976) drenched volunteer subjects with very dilute solutions of CR and CS for durations of 15 and 60 s. In the studies comprising subjects that were exposed individually, stinging of the skin around the eyes was rapid in onset, which spread to other parts of the face. The burning sensation involving facial skin was the next pronounced feature for approximately the first minute. Scalp and ears were not usually affected. During the second minute, stinging was associated with the back of the neck and irritation of the genital area. Stinging of the shoulder and back followed at 3–4 min and the burning sensation was intense by about 5 min. Other anatomical sites (e.g. chest, abdomen, thighs, and buttocks) were affected at about 5 min. The burning sensation of the skin was intense primarily affecting the trunk and back at about 10 min. Approximately 15 min from the onset of exposure, the skin sensation had subsided. By 20 min skin sensations were reduced to mild tingling or had disappeared. Erythema of the skin was produced within several minutes and persisted for 1–2 h, and no other skin effects were noted. Many areas of the skin were rather resistant to irritation, which included such sites as the ears, nose, scalp, palms of the hands, knees, and the lower legs. In general, a more intense response was elicited by CR at higher concentrations; however, it should be noted that individual variations were more marked than the differences between CR concentrations. In the group drenching studies, burning of the skin was the most prominent symptom. As with the individual drenches, considerable variation in the severity of the symptoms was manifested. Compared with CR, the effects elicited by CS were less severe, of shorter duration, and more variable. Stinging of the skin followed a similar progression (face, neck, genital areas, shoulders and back, chest, abdomen, and thighs) as seen with the CR drenches. The studies by Ballantyne and coworkers (1976) demonstrated that very dilute solutions of CR and CS produce a strong stimulation of sensory receptors in the skin and mucous membranes. The burning sensation was more intense and of longer duration on exposure to CR than with CS. Skin irritation and erythema was evident following exposure to either CR or CS and the signs were more pronounced with CS than with CR. No individual drenched with CR or CS manifested edema, vesication, or desquamation.

5.4.2 Chloroacetophenone and chlorobenzylidene malononitrile Cutaneous reaction to CN and CS exposure is not immediate, the stinging that develops within several minutes is much less severe than that of the eyes and nasal passages. Dilute solutions of CS as demonstrated in studies by Ballantyne et al. (1976) elicit a marked stimulation of somatosensory receptors in the skin. The comparative dermal irritancy potential of RCAs was covered earlier in the discussion on the dermal sensory irritancy of CR.



5.4.3 Capsaicin/capsaicinoids/oleoresin capsicum Exposure to low levels of acyl amides such as capsaicin and its congeners produces an intense burning sensation of the skin accompanied by erythema and an inflammatory response. Capsaicin-induced inflammation of the skin is believed to be a consequence of substance P release (Lynn and Shakhanbeh, 1988). Dermal exposure to aerosolized OC produces an intense burning pain, tingling, erythema, and at higher concentrations and/or exposure durations edema and occasionally blistering. The dermal sensory response was studied in human subjects following topical application of capsaicin (Smith et al., 1970; Carpenter and Lynn, 1981). Topical application of capsaicin has resulted in the depletion in the skin of an array of biochemical constituents to include substance P, somatostatin, prostaglandin, and acetylcholine (Buck and Burks, 1986).

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MAYNARD, R.L. (1999) Toxicology of chemical warfare agents. In: B. BALLANTYNE, T. MARRS, and T. SYVERSEN, (eds), General and Applied Toxicology, 2nd edition, London: Macmillan Reference Ltd, p. 2103.

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SARTORI, M. (1943) The War Gases, New York: D. Van Nostrand, Co. Inc. SATO, Y., KISHI, T., and UMEMURA, T. (1998) Histopathological and immunohistochemical studies on experimental asthmatic model induced by aerosolized ovalbumin inhalation in guinea pigs, Journal of Toxicological Sciences, 23: 69–75. SHIMIZU, T., FUJITA, S., IZUMI, K., KOJA, T., OHBA, N., and FUKUDA, T. (1984) Corneal lesions induced by the systemic administration of capsaicin in neonatal mice and rats, Naunyn-Schmiedebergs Archives of Pharmacology, 326: 347–351. SIDELL, F.R. (1997) Riot control agents, In: Textbook of Military Medicine, Medical Aspects of Chemical and Biological Warfare, Washington, DC, Office of the Surgeon General, US Army, TMM Publications, Borden Institute, pp. 307–324. SMITH, J., CROUNSE, R., and SPENCE, D. (1970) The effects of capsaicin on the human skin, liver, and epidermal lysosomes, Journal of Investigative Dermatology, 54: 170–173. SURH, Y.J. and LEE, S.S. (1995) Capsaicin a double-edged sword: toxicity, metabolism, and chemoprotective potential, Life Sciences, 56: 1845–1855. TSUBONE, H. and KAWATA, M. (1991) Stimulation of the trigeminal afferent nerve of the nose by formaldehyde, acrolein, and acetaldehyde gas, Inhalation Toxicology, 3: 211–222. VESALUOMA, M., MULLER, L., GALLAR, J., LAMBIASE, A., MOILANEN, J., BELMONTE, C., and TERVO, T. (2000) Effects of oleoresin capsicum pepper spray on human corneal morphology and sensitivity, Investigative Ophthalmology and Visual Sciences, 41: 2138–2147. WEIGAND, D.A. and MERSHON, M.M. (1970) Cutaneous reaction to EA 3547 in propylene glycol, Edgewood Arsenal Technical Report No. EATR–4413, July 1970, US Army Medical Research Laboratory, Edgewood Arsenal. ZOLLMAN, T.M., BRAGG, R.M., and HARRISON, D.A. (2000) Clinical effects of oleoresin capsicum (pepper spray) on the human cornea and conjunctiva, Ophthalmology, 107: 2186–2189.


CHAPTER

Pharmacology/Toxicology of CS, CR, CN, Formulations, Degradation Products, Carriers/Solvents, and Propellants

6

EUGENE J. OLAJOS1 AND JOAN M. LAKOSKI2 1 US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 2 Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburg, Pennsylvania

6.1

INTRODUCTION

This chapter considers the pharmacological and toxicological responses of the organism to the modern-day riot control agents (RCA) o-chlorobenzylidene malononitrile (CS), dibenz[b,f ]1:4-oxazepine (CR), and chloroacetophenone (CN). The animal pharmacology/toxicology of modern riot control agents (RCAs) CS, CR, and CN are presented – and in some instances reference to the human toxicology of RCAs is made to address the comparative toxicological aspects. This discussion is augmented by also addressing the toxicology of RCA formulations, the toxicology of degradation and decontamination products as well as an abbreviated overview of the toxicology of carriers/solvents and propellants used in RCA formulations. The pharmacology and toxicology of oleoresin capsicum (OC) and capsaicinoids are covered in Chapter 7, and a detailed account of the human pharmacology/toxicology of CS, CR, and CN is presented in Chapter 11 by Stopford and Sidell. RCAs are generally regarded as having minimal toxicity and have been described as nonlethal. Individuals may be exposed to RCAs via the inhalation, dermal, or oral routes. Organ systems that may be affected by RCAs include the eyes, lungs, skin, the gastrointestinal tract, and the immune and endocrine systems. The quantity of RCA needed to cause serious adverse actions is many times greater than the amount required to elicit an intolerable effect. Permanent adverse effects are usually not associated with RCA exposure; however, the risks for deleterious effects, long-term effects or even lethality increase with higher exposure levels and/or greater exposure times. Two contrasting viewpoints exist regarding the potential of RCAs to produce adverse health effects. The most commonly held view is that high levels of RCAs are precluded because individuals are averse


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to remaining where RCA is present – consequently adverse health effects are minimized. The alternate viewpoint stems from the observation of more critical authors on the lack of epidemiologic inquiry on RCA use in actual field conditions. Individuals under certain circumstances and conditions may be exposed to high concentrations of RCA. It is certainly plausible that in certain situations an individual may not have the opportunity or be able to leave a contaminated area and are thus at risk to a high exposure concentration of RCA.

6.2 MAMMALIAN PHARMACOLOGY/TOXICOLOGY OF RCAS 6.2.1

Chlorobenzylidene malononitrile (CS)

The riot-control agent CS was developed in the l950s as a potent and safe RCA. CS has been extensively studied in both animals and humans, and has been widely utilized – there are no verified deaths in humans following CS use (Ballantyne, 1977a). As discussed in the previous chapter on peripheral sensory irritation of RCAs (Chapter 5), CS is highly irritating to mucous membranes that cover or line tissues of the eyes, nose, throat, and stomach. Irritation of the gastrointestinal tract may cause vomiting and/or diarrhea. Exposure of the skin to CS results in a burning sensation, which may be followed by inflammation and erythema. The skin effects may be more severe and result in blistering particularly when exposure occurs in hot and humid conditions – refer to the section on dermatotoxicology of CS for a more in-depth discussion. Within 30 s of exposure, some or all of the aforementioned effects may occur and subside and/or disappear within minutes on cessation of exposure. The level of irritation during exposure is of such magnitude that it causes an exposed individual to seek escape from the exposure. In this chapter, the pharmacology and toxicology of CS are discussed describing the actions of CS on the eyes, the pulmonary, cardiovascular, the immune and endocrine systems, and the skin as well as extra-pulmonary tissues such as the liver and kidneys to include associated pathological changes. Pathological changes involving extra-pulmonary tissues, namely, liver and kidneys following exposure to high concentrations of CS are secondary to respiratory and circulatory failure. The lethal effect of CS by inhalation is due to lung damage, which leads to asphyxia and circulatory failure. Bronchopneumonia secondary to respiratory tract injury may also be the cause of death. The pharmacology of CS was initially studied by Biscoe and Shephard (l962) and further elaborated by Brimblecombe et al. (l972). In the studies by Brimblecombe and coworkers, the pharmacological/toxicological effects of neat and pyrotechnically disseminated CS were studied in various animals via different routes of administration – in vitro studies were also conducted. A typical response to CS following intravenous administration; for example, was a rise in arterial blood pressure. Qualitative and quantitative species differences were noted following CS administration; for example, dogs appeared less sensitive than cats to the cardiovascular effects of CS. Oral administration of CS to animals produced rapid shallow breathing, increased salivation, tremor, reduced locomotion, and piloerection. Depending on dosage, orally administered CS can produce hemorrhagic erosion, congestion, and edema of the gastric mucosa and congestion of other organs, namely, the spleen, small intestine, and lungs (Ballantyne and Swanston, 1978). Of further note is that renal damage may also occurr following oral dosing with CS. In comparison with other RCAs (i.e. CN), CS is less toxic than CN, and the intra-abdominal pathology of animals surviving or dying following oral administration is considerably less than seen after oral administration of CN. Animals exposed via inhalation to


PHARMACOLOGY/TOXICOLOGY OF CS, CR, AND CN

pyrotechnically generated CS or pure CS aerosol exhibited changes in respiratory function and/or morphology. Severe lung injury and consequently respiratory and circulatory failure are characteristic findings in experimental animals after inhalation exposure to high CS concentrations. The lethal effect of CS by inhalation is due primarily to pulmonary injury, which leads to asphyxia and circulatory failure. CS is considered generally safe; however, as with this class of compounds, exposure to high concentrations can lead to adverse biological effects in experimental animals and humans (Rose and Smith, 1969; Punte et al., l962b; Owens and Punte, 1963; Beswick et al., 1972; Ballantyne and Callaway, l972; Alarie et al., 1973; Colgrave and Creasey, 1975; Ballantyne et al., 1976a; Ballantyne, 1977a; Ballantyne and Swanston, 1978; Marrs et al., 1983a,b; Debarre et al., 1999). Studies have been conducted to characterize the acute toxicology of CS, which have included incapacitating studies via aerosol or vapor exposure. The inhalation toxicity of RCAs – as in the case with military chemicals and chemical warfare agents – is by convention expressed by the notation Ct. This term is defined as the product of the concentration in mg/m3 multiplied by the exposure time (t) in minutes (mg-min/m3). The terms LCt50 and ICt50 describe the airborne dosage lethal (L) or incapacitating (I) to 50% of the exposed population. The dosage expressed, as Ct does not necessarily bear a simple relationship to the amount of toxicant actually absorbed by the organism exposed to a toxic substance. However, experience with many inhaled toxic materials confirms that a probit transformation does provide a reasonably linear relationship with log dosage, providing that time and concentration do not vary over wide ranges. The underlying assumption is that at any given concentration absorption (uptake) is proportional to the time of exposure. The findings from a number of animal studies on CS have been summarized (Ballantyne, 1977a; NAS, 1984). A spectrum of animal species (e.g. rats, mice, guinea pigs, and rabbits) were acutely exposed to CS as either pure material or smoke (grenade). CS-induced effects were immediate and animals recovered shortly after cessation of exposure to test article. Studies on the acute toxicity of molten CS in animals indicated an order of sensitivity to molten CS as follows: guinea pig rabbit rat dog mouse monkey. The results from acute exposures to CS, disseminated as molten agent, is presented in Table 6.1. The results, expressed as LCt50 values, from exposures of rats and guinea pigs to CS, dispersed from thermal grenades (M18), were as follows: rats (164,000 mg-min/m3) and guinea pigs (36,000 mg-min/m3). Species sensitivity to thermally generated CS was swine dog rabbit goat guinea pig rat monkey. Results from acute exposure to CS, dispersed from thermal grenades (M7A3), are summarized in Table 6.2. Ballantyne and Callaway (1972) also studied the inhalation toxicity of pyrotechnically generated CS smokes. Animals (rats, mice, guinea pigs, and rabbits) were exposed for

TABLE 6.1 Comparative toxicity values for molten CS Species

LCt50 (mg-min/m3)

Rat Mouse Guinea pig Rabbit Dog Monkey

32,000 42,000 8,000 17,000 34,000 50,000


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durations of 5, 10, 15, or 20 m to a very high concentration of CS (~4 g/m3) – a level about 1,000 times the amount considered effective. Animals exhibited signs of upper respiratory tract irritation and dyspnea. None of the animals exposed to CS grenade smoke (dosages between 19,750 and 86,000 mg-min/m3) died during exposure. Gross and histological examination of the lungs revealed pulmonary injury. Indication of circulatory failure, as evidenced by slightly enlarged livers, congestion of the liver and kidney, and dilatation of the right ventricle, was also noted. The inhalation toxicity of CS2, a CS variant has also been evaluated. CS2 is comprised of 95% CS, 5% Cab-o-Sil®, and 1% hexamethyldisilazane. The results from acute exposure to CS2 are as follows: rats (LCt50 68,000 mg-min/m3); guinea pigs (LCt50 49,000 mg-min/m3); dogs (LCt50 70,000 mgmin/m3); and monkeys (LCt50 74,000 mg-min/m3). Lethality estimates for CS and other commonly used RCAs are given in Table 6.3.

TABLE 6.2 Comparative toxicity values for thermally dispersed CS Species

LCt50 (mg-min/m3)

Rat Guinea pig Rabbit Swine Dog Goat Monkey

94,000 66,000 38,000 17,000 30,000 48,000 120,000

TABLE 6.3 Comparative toxicity (LCt50) of CNa, CSa, and CRb Route

Inhalation Pyrotechnically generated Aerosol

LCT50 (mg-min/m3)c

Species

Rat Mouse Rabbit Rat Mouse Guinea pig Rabbit

CN

CS

139,000 — 15,800 3,700 –18,800d 18,200–73,500d 3,500–13,140d 5,840–1,480d

68,000 76,000 63,000 88,460 67,200 50,010 54,100

Notes a Data from several sources as documented in a report by the NAS (1984). b Data from several sources as reported by Ballantyne (1977a). c Lowest value reported. d Range of values from several sources.


CR

23,000 203,600 160,000 428,400 169,500 169,500 169,000


Cyanogenic potential of CS The concern regarding the cyanogenic potential of CS stems from the potential for cyanide formation in vivo following exposure to CS as well as potential exposure to hydrogen cyanide (HCN) – a product of the thermal decomposition of CS. Since Patai and Rappoport (1962) demonstrated the hydrolysis of CS to malononitrile – a known potent cyanogen, studies have been conducted to assess the cyanogenic potential of CS. Jones and Israel (1970) postulated that some of the toxic effects attributed to CS could be due to the metabolic conversion of CS to cyanide via the malononitrile intermediate. Cucinell et al. (1971) confirmed that the toxicity of CS via parenteral administration was due to the rapid metabolism of CS resulting in the formation of cyanide. Moreover, the liberation of HCN during the pyrotechnic dissemination of CS is also a matter of concern owing to the potential for cyanide intoxication. It was addressed early on by several investigators and has received recent attention as a result of studies by Kluchinsky et al. (2002a) on CS-derived thermal degradation products. Studies by Kluchinsky and colleagues (Kluchinsky et al., 2001) demonstrated the presence of 3-(2-chlorophenyl) propynenitrile, as one of the thermal degradation products of CS, which indicate the loss of HCN from CS. It is understandable that considerable interest has evolved regarding the cyanogenic properties of CS because cyanide is a highly toxic and rapidly acting poison. Cyanide is readily diffusible through the epithelium; this property contributes to its toxicity following inhalation exposure to HCN, ingestion of cyanide salts and cyanogens, or percutaneous absorption of cyanide from solutions. The toxicodynamic effects can vary depending on the dose, route, chemical form of the cyanide and other factors. HCN is readily taken up and widely distributed in biological fluids and tissues and is in an equilibrium with low concentrations of cyanide ion. Cells of the brain, especially the brainstem, are very sensitive to the effects of HCN and dysfunction may lead to respiratory arrest. Besides affecting the function of the central nervous system (CNS), cyanide can alter the functions of the pulmonary, cardiovascular, autonomic, and visual systems of the body. In regards to its effect on respiratory dynamics, HCN stimulates the chemoreceptors of the carotid and aortic bodies, which leads to hyperpnea resulting in greater uptake of CS and CS degradation products. Exposure to HCN vapor, released as a pyrolysis product, can lead to physical incapacitation, muscle weakness, difficulty in coordination, a confusional state, and partial or complete loss of consciousness. Regarding biochemical processes, cyanide is capable of inhibiting or modifying a variety of enzyme systems and biochemical pathways – the biochemical basis for cyanide poisoning is complex (Way, 1984). It is widely accepted that the major biochemical mechanism of cyanide poisoning, accounting for at least a significant part of its actions, is the ability of cyanide to inhibit the critical enzyme cytochrome c oxidase, which leads to impaired cellular respiration. A number of metabolic pathways function to detoxify the cyanide ion. The most important route of cyanide elimination is via the formation of thiocyanate, which is excreted in the urine. Thiocyanate formation is catalyzed directly by the mitochondrial enzyme rhodanese and indirectly via the reaction between cyanide and the persulfide sulfur products of the enzymes mercaptopyruvate sulfurtransferase and thiosulfate reductase (Westley et al., 1983). Minor routes of metabolism of cyanide involve its oxidation to the cyanate via enzymatic and nonenzymatic pathways. Studies, both in animals and humans, to assess the cyanogenic potential of CS include those of Cucinell et al., 1971; Frankenberg and Sorbo, 1973; Ballantyne, 1983. Increase in plasma thiocyanate concentration was noted in dogs following exposure to very high aerosol concentrations of CS or on i.p. administration – free cyanide was also detected following the administration of CS (Cucinell et al., 1971). Ballantyne (1983) conducted an extensive study to ascertain the cyanogenic potential of CS following i.p. injection.


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Results, namely, elevated serum thiocyanate levels, body fluid and tissue cyanide levels, and significant inhibition of tissue cytochrome oxidase activity collectively demonstrated that the acute lethal i.p. toxicity of CS and malononitrile was due to cyanide formed via the metabolic conversion of CS and malononitrile. In light of the in vivo cyanogenic potential of CS administered via the i.p. route, it is important to relate this to potential toxicity by inhalation of CS. CS is readily absorbed by the respiratory tract as indicated by the detection of the CS metabolites 2-chlorobenzaldehyde and 2-chlorobenzyl malononitrile in animals exposed to aerosolized CS (Leadbeater, 1973). Moreover, Frankenberg and Sorbo (1973) provided evidence for the urinary excretion of thiocyanate following exposure to high inhalation doses of CS aerosol. In the context of human exposure to CS, the likelihood of toxicologically significant amounts of in vivo cyanide formation is somewhat unlikely for the following reasons: (1) Exposure of humans to CS is limited by the potent sensory irritant effects, and the amount of cyanide that could be produced by an intolerable concentration of CS would be rather minute, and (2) Humans have a highly effective sulfurtransferase detoxification mechanism for cyanide, to absorb toxicologically significant amounts of CS, with respect to cyanogenesis, would necessitate an exposure to very high concentrations and/or prolonged exposure to CS. Ballantyne and Swanston (1978) point out that an exposure to CS under the following conditions (a concentration of 10 mg/m3, a respiratory minute volume of 20 liters, a one minute exposure, and complete retention of inhaled CS) would result in a CS uptake of about 1 mole. Since only one nitrile is effectively cyanogenic, the cyanide yield would be ~1 mole, – an amount comparable to the quantity of cyanide in a 30 ml puff from a cigarette (Osborne et al., 1956). Sanford (1976) has reported that an individual 20–30 meters downwind from a 50 g CS cartridge would retain at most 2.1 mole of cyanide – an amount comparable to that present in two puffs of a cigarette (editorial, Lancet (1971)). More recently, Yamanaka et al. (1991) suggest that the cyanide concentration in mainstream cigarette smoke is in the range of 40–70 ppm. On this basis, a 30 ml puff of a cigarette may contain 0.04–0.08 mole or 1–2 g of cyanide. Thus, based on the Yamanaka et al. estimate of cyanide levels in a cigarette puff, the cyanide yield from exposure to 10 mg/m3 for one minute is roughly one order of magnitude greater than the cyanide levels detected in a 30 ml puff of a contemporary cigarette product. The low cyanide yield expected from breathing an atmosphere of CS, most likely encountered in a riot control situation, is consistent with the observation that urinary thiocyanate is not elevated in humans exposed to CS aerosols and the findings reported by Leadbeater et al. (1973).

6.2.2 Dibenz[b, f]1:4-oxazepine (CR) CR a potent sensory irritant of low toxicity, is a more recent addition to the riot control family of compounds. The ocular and dermal irritant effects are more transitory than those of other RCAs. Vesication and contact sensitization are not associated with CR exposure. The pharmacology and toxicology of CR has been extensively studied. CR is characterized as having low acute toxicity based on findings in various animal species exposed to CR via various exposure routes – the data having been summarized by Ballantyne (1977a,b). Ballantyne (1977b) demonstrated that CR, by all routes of exposure, is less toxic than CN or CS. Animals dosed with CR exhibited rapid breathing, ataxia (incoordination), spasms, and convulsions. Generally, these effects gradually subside over a l5 to 60 min period and the animals appear normal or there is marked respiratory distress and death. No histological abnormalities were noted in CR-treated animals. Pathologic changes noted in animals orally or intravenously dosed with CS or CN



consisted of congestion of alveolar capillaries and liver sinusoids. Following i.p. administration of CR, compound-related effects included muscle weakness and heightened sensitivity to handling. Toxic effects persisted through the first day after exposure and some animals exhibited CNS effects. Animals surviving the post-exposure period exhibited no gross or histological abnormalities at necropsy. In a series of studies, Lundy and colleagues (Lundy and McKay, 1975, 1977; Lundy, 1978) evaluated the effects of intravenously administered CR on the cardiovascular system. A dose-dependent increase in blood pressure of short duration was observed. Moreover, stimulation of the heart rate and increased arterial catecholamine content were also noted following treatment with CR. The authors postulated that the CRinduced cardiovascular response was associated with sympathetic nervous system effects as evidenced by the abolition of CR-induced pressor effect by phentolamine and 6-hydroxydopamine.

6.2.3 Chloroacetophenone (CN) Chloroacetophenone, a white crystalline solid with an apple blossom odor, is commonly known as tear gas or Mace® and has the military designation CN. First synthesized in l871, CN was studied for its use as a tear gas shortly after the First World War. CN acts directly on the mucous membranes to produce intense ocular and respiratory irritation and associated burning and pain sensation of the eyes, nose, throat, and lungs. Ocular effects consist of lacrimation, blepharospasm, and conjunctivitis. Irritation of the respiratory tract produces sneezing, coughing, secretions, nasal congestion, and a sense of suffocation. The onset of some or all of these symptoms is immediate and persist for up to 20 min after removal from the contaminated atmosphere. Acute and repeated-dose inhalation studies have been conducted in various animals to ascertain the comparative toxicity of CN. The toxicology of CN has been reviewed and summarized in a NAS report (NAS, 1984) and by Hu et al. (1989). Early toxicity studies on CN were highly variable, and studies subsequently conducted in the mid-l960s, in various animal species, were designed to provide more quantitative data. In these studies, CN was dispersed in acetone or from commercially available thermal grenades. Sublethal effects noted on exposure to CN consisted of lacrimation, conjunctivitis, copious nasal secretions, salivation, hyperactivity, dyspnea, and lethargy. Cutaneous effects seen in the exposed animals consisted mainly of erythema. The salient biological finding, exhibited by all exposed animals, on post-exposure was dyspnea. Ocular effects (i.e. conjunctivitis) and dermal effects (i.e. erythema) persisted for 3–7 days after exposure. The primary cause of death following CN inhalation was from the injurious action of CN on the pulmonary system. Punte et al. (1962a) reported LCt50 values of 3,700, 73,500, and 3,500 mg-min/m3 for rats, mice, and guinea pigs, respectively.

6.3 ORGAN-SPECIFIC TOXICITY OF RCAs 6.3.1 Ophthalmic toxicology Ocular injuries by chemical substances, including RCAs, may be mild and transient in nature or may result in permanent damage or loss of an eye. The type and severity of ocular lesions produced by a chemical are determined by such factors as concentration, exposure duration, and the physical properties of the compound. Concentration and


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duration of exposure are readily understood factors; however, the physical properties of a chemical – as contributing factors to toxicity – are not always as easily understood, as is in the case of compound solubility. Pertaining to ocular injury, a substance that is able to penetrate the cornea quickly is more likely to produce severe corneal damage. Generally, lipid-soluble compounds, which include the lacrimators, pass through the corneal epithelium readily and consequently produce corneal damage. However, the poor water solubility of lacrimatory compounds also accounts in part for the corneal injury being limited most often to the epithelium. Thus, depending on agent concentration, exposure duration, and physico-chemical factors, varying degrees of edema, conjunctival irritation, corneal lesions/abnormalities, and scarring will be seen. To some extent, the various ocular injuries are repairable without permanent damage – depending on the chemical and other factors. In low concentrations, RCAs produce irritation, with a copious flow of tears and uncontrollable closure of the eyelids (blepharospasm) – these responses are transient. At higher concentrations and/or prolonged exposure durations, RCAs may lead to more deleterious ocular effects. It should be further noted that the degree of ocular injury is related not only to the amount and type of RCA, but is also dependent on the method of dissemination. Ocular injuries are more prevalent following use of explosive (thermal type) tear gas devices as contrasted to defense spray devices. Corneal edema, which is reversible, is a consequence of excessive exposure to RCAs. Severe ocular injury (e.g. corneal opacification, ulceration with vascularization) may result, particularly on exposure to high concentrations and/or extended exposure to an RCA – particularly CN. Severe ocular injury is also associated with the older lacrimatory compounds such as bromobenzyl cyanide. Regarding the chemical actions of substances with ocular tissue, particularly with corneal tissue, one can state that many chemicals have the capability of altering protein structure and/or interfering with enzyme function. These interactions involving macromolecular moieties result in alterations that may or may not be reversible. Much of the change in corneal tissue resulting from chemical exposure is due to interactions with corneal proteins and enzymes. Levine and Stahl (1968) have postulated that lacrimatory compounds such as CN produce a denaturation action on tissue proteins, resulting in conjunctival and corneal damage. This view stems from the putative alkylating properties of CN and similar compounds. The reader is referred to a large body of data in the scientific literature pertaining to RCA-induced ocular injury (Oaks et al., 1960; Midtbo, 1964; Hoffmann, 1965, 1967; Braegeat, 1968; Levine and Stahl, 1968; MacLeod, 1969; Rengstorff, 1969b; Rengstorff and Mershon, 1971a,b; Ballantyne et al., 1975; Oksala and Salminen, 1975; Rengstorff et al., 1975). The ocular toxicity of modern RCAs and RCA/solvent combinations as well as the ocular toxicity of solvents used in defense spray formulations are presented.

o-Chlorobenzylidene malononitrile The effects of aqueous and nonaqueous CS formulations on the eyes have been extensively investigated in both laboratory animals and human subjects (Punte et al., 1962b; Rengstorff, 1969a; Rengstorff and Mershon, 1971a,b; Rengstorff et al., 1971; Gaskins et al., 1972; Ballantyne and Swanston, 1973; Ballantyne et al., 1974). Studies by Punte et al. (1962b) were conducted to evaluate the effects of CS on the rabbit eye following topical application of test material. A common finding was conjunctivitis, which had completely subsided within several hours. Moderate injury involving corneal tissue was not observed, and application of more concentrated solutions of CS had no effect on the corneal tissue. Subsequent studies by other investigators have demonstrated that the potential for eye damage with CS is considerably less than with CN (Gaskins et al., 1972; Ballantyne et al., 1974). Moreover, findings by Ballantyne and Swanston (1973) have indicated that the human eye is more sensitive to CS aerosol than to CS solution.



Studies assessing the potential for eye damage from short-range discharge of CS aerosol generators (aerosol irritant projectors) have been conducted by a number of investigators (Hoffmann, 1965; Macrae et al., 1970; Ballantyne, 1979). In studies by Ballantyne (1979), the ocular effects of aerosolized CS dispensed from a hand-held canister containing active ingredient (10% w/v) in dichloromethane with dichlorofluoromethane as propellant were assessed. In these studies, the right eye of rabbits was exposed for a duration of one second to the aerosol spray at a distance of either 6 or 24 inches. The close range (6 inches) discharge of the CS aerosol canister resulted in inflammation of the eye and periocular (periorbital) tissues and in some instances keratitis. The gross and histological appearance of the eye following close-range discharge of CS was typical of chemically induced ocular injury. Ocular effects resulting from the discharge of the CS canister at two feet consisted of excessive lacrimation and conjunctival injection. These ophthalmic responses are anticipated on exposure to a simple aerosol of CS, as described previously by Ballantyne et al. (1974). Ballantyne postulated that the ocular inflammation observed following short-range exposure to CS from aerosol canisters was the result of the combined actions of CS and dichloromethane since at close range the eye was exposed to CS and unvolatilized solvent. Previous studies had demonstrated that CS, in mild irritating solvents such as polyethylene glycol 300 (Ballantyne et al., 1974) or liquid dichloromethane alone (Ballantyne et al., 1976b) both produced blepharitis and keratitis.

Dibenz[b,f]1:4-oxazepine Irritancy studies of 1% CR solutions (see Chapter 5) have demonstrated that the ocular effects observed were mild and transitory in nature. The ocular effects of more concentrated CR solutions have also been evaluated (Rengstorff et al., 1975). Results indicated a moderate degree of conjunctivitis; however, histological examination of the eyes revealed normal corneal and eyelid tissues. A comparative ophthalmic toxicity study on CR and CN using rabbits was conducted by Ballantyne et al. (1975). In this study, ocular effects were evaluated following aerosol exposure to test article (Ct 360–719 mg-min/m3) or instillation of RCA either as a solution (1–10% in polyethylene glycol) or as a solid (0.1–5 mg). In solvent, CN produced marked and persistent inflammation – the severity and duration dependent on the concentration used. The corneal injury observed was marked and persistent. Solutions of CR or CN produced increases in corneal thickness, whose magnitude and duration were concentration-dependent, being significantly less marked with CR. The ocular injury produced by the application of solid CN was more severe than with similar amounts of solution. In marked contrast, CR in solution produced mild to moderate inflammatory effects, which persisted for only a few days – even at the higher concentrations. The high concentration CR solution resulted in just detectable keratitis, which had resolved within several days. Solid CR produced only minor irritation of the conjunctivae and eyelids. Aerosols of CR and CN did not produce damage to the eyes; however, irritation of the lids and conjunctivae were more pronounced and persistent following exposure to CN. The collective data on the ocular irritancy induced by CR suggest that this RCA produces less pronounced ocular effects than; for example, as seen following CN exposure.

Chloroacetophenone Studies to ascertain the ocular irritancy and injury potential of CN, administered as a liquid, solid, or aerosol, date from the 1930s. These studies have demonstrated that high concentrations of CN can cause severe ocular complications such as opacification, ulceration with vascularization, keratitis, and conjunctival sloughing. Grant (1964), in his description of the ocular effects of RCAs, refers to CN’s marked ability to produce


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permanent opacification. Macleod (1969) studied the ocular effects of chemical Mace® in rabbits and monkeys. Findings from these studies demonstrated that CN, administered to monkeys to simulate field exposure, had resulted in minimal eye injury. The lesions persisted for several days and then disappeared. The liquid application of chemical Mace® to the eyes of monkeys resulted in permanent corneal surface irregularities. When CN was applied directly to the eyes of rabbits, permanent scarring, sufficient to cause visual impairment, was noted. CN has also been reported as having the potential to produce neuroparalytic keratopathy (Leopold and Lieberman, 1971). Gaskins et al. (1972) conducted tests to assess the relative ocular hazards of CN and CS in a variety of organic solvents. Laboratory and commercial preparations containing CN were evaluated. Commercial preparations (containing CN concentrations between 0.04% and 4.3% w/v) were sprayed directly into the eyes of rabbits, and for some sprays, the effluent was collected and instilled directly (0.1 ml) into the animals’ eyes. Formulations, which contained CN at concentrations between 0.04% and 1.0%, did not produce permanent eye injury. Laboratory and commercial products containing more than 4% w/v CN produced permanent corneal injury. Compared to CS, CN had a greater irritative effect – laboratory preparations containing 10% w/v of CS produced no corneal injury. A systematic approach to ascertain the ophthalmic toxicity of CN, administered as an aerosol or topically in the form of a solid or liquid, was undertaken by Ballantyne and co-workers (1975). In these studies, the ophthalmic toxicity of CN as an aerosol, in the form of a liquid (1–10% in polyethylene glycol 300), or as a solid was evaluated. Aerosols of CN were generated from a 20% (w/v) solution of CN in dichloromethane to yield CN dosages between 360–719 mg-min/m3. Exposure durations were for fifteen minutes. CN produced ocular effects after instillation or following exposure to CN aerosols. For a description of effects, refer to the preceding discussion on the comparative ocular effects of CN and CR.

6.3.2

Pulmonary toxicology

The mammalian lung has evolved into a complex organ whose function goes beyond providing a means for the exchange of oxygen and carbon dioxide (CO2). The lung also functions as an exocrine organ (e.g. homeostasis/regulation of biogenic amines, angiotensin, and prostaglandin), as an excretory organ involved in the elimination of toxicants – either inhaled or absorbed via other routes, and as a major site of metabolism for a wide array of xenobiotics. The lungs are sensitive to toxic injury, and foreign substances can enter the respiratory tract as vapors, aerosols, or as solids and are rapidly taken up and transported to other organs. The responses of the pulmonary system to xenobiotics can be categorized as follows: (1) irritation, (2) air way constriction/dilatation, (3) alveolar and pulmonary cell injury, (4) fibrosis, and (5) oncogenesis. The respiratory tract at all levels (nasopharyngeal, tracheobronchial, and the pulmonary) is a major site of action of peripheral sensory irritants to include the RCAs. These substances are highly irritative to the pulmonary tract at very low concentrations (refer to Chapter 5), and at high concentrations are injurious to the respiratory system. The pulmonary toxicology of RCAs is summarized next.

Chlorobenzylidene malononitrile A number of animal studies have addressed the toxicology and pathology produced by inhalation exposure to CS (Punte et al., 1962b; Cucinell et al., 1971; Ballantyne and Callaway, 1972; Colgrave and Creasey, 1975; Ballantyne and Swanston, 1978; Marrs et al., 1983a,b; Debarre et al., 1999). The physiological and toxicological effects of CS in rats and dogs, exposed to CS aerosol, were studied by Cucinell et al. (1971). Since lungs of



animals exposed to RCAs manifest edema, hemorrhage, and atelectasis; studies in rats were conducted to assess the surfactant and lysosome activity from lung washings of CS-exposed rats. In these studies, rats were exposed to CS aerosols at Ct values that ranged from 40,000 to 80,000 mg-min/m3. Findings indicated an increase in the surface tension of the saline washouts of lungs from CS-exposed animals. Analysis of lung lavage fluid from CS-exposed animals indicated an increase in -glucuronidase suggestive of lysosomal activity following injury to the pulmonary tract. Dogs were exposed to CS aerosol at either a low or a very high concentration of test article. In the low-dose segment, the face of the animal was exposed to an airborne concentration of 25 g/L of CS for 30 s. In the high-dose study, the animals were exposed to an aerosol concentration of 2,500 g/L for 23 min, which is equivalent to a Ct of 57,000 mg-min/m3. Physiological effects noted on exposure to the low level of CS aerosol consisted of alterations in respiratory patterns and an increase in blood pressure. The pattern of response observed was suggestive of the Sherrington pseudoaffective response (Lim, l968). Exposure to a very high level of CS aerosol resulted in respiratory stress and mortalities; however, details were not given. Ballantyne and Callaway (1972) studied the pulmonary effects of pyrotechnically disseminated CS. Animals were exposed to high dosages of CS (19,750–86,000 mg-min/m3). Gross examination of pulmonary tissue indicated the following toxic effects: edema and congestion of the lungs with foci of hemorrhage and excessive amounts of mucous in the trachea and bronchi. Histological examination of pulmonary tissue demonstrated moderate to severe congestion of the alveolar capillaries, alveolar hemorrhage, areas of atelectasis, and edema. Surviving animals sacrificed at 14 days post-exposure appeared normal suggesting that any lung damage in these animals was transient. The effects of pyrotechnically generated CS on lung morphology, including an assessment of pulmonary fine structure, was studied by Colgrave and Creasey (1975). In these studies, rats were exposed to very large dosages (30,000–90,000 mgmin/m3). Exposure to very high concentrations of CS grenade smoke resulted in pulmonary congestion and severe capillary damage resulting in pulmonary edema and hemorrhage. Conventional histological examination revealed variable degrees of congestion, hemorrhage, and edema. Electron microscopy demonstrated changes to the alveolar epithelium and interstitium. The presence of fluid was associated with degenerative changes of the epithelium and endothelium with consequent dissolution of the capillary wall and extravasation of red blood cells and fluid in the alveolar space. The electron microscopic findings were in general agreement with results reported by other investigators regarding acute pulmonary edema in animals (Cottrell et al., 1967). The possibility for long-term health consequences of exposure to a single large dose of CS – a pattern of exposure most likely to resemble the likely pattern of exposure of rioters – prompted Marrs et al. (1983a) to investigate the potential of CS to induce long-term sequelae. Animals (rats and hamsters) were acutely exposed to pyrotechnically generated CS smoke at high concentrations and prolonged exposure periods (480 mg/m3 for 1 h; 150 mg/m3 for 2 h) and retained for 32 months. Findings indicated no long-term adverse effects from a single prolonged exposure to suprathreshold concentrations of CS. Findings as described by Marrs et al. (1983a) are reassuring; however, concerns remain, including the potential for exacerbation of preexisting disease and for chronic toxicity. Reports particularly relevant to the issue of “teargas”-induced chronic toxicity is that of Hu and Christiani (1992) and Roth and Franzblau (1996) wherein the authors describe the occurrence of reactive-airways dysfunction syndrome (RADS) following exposure to CS or to CS/OC. RADS can result following a single excessively high environmental or occupational irritant exposure (Brooks et al., 1985a,b). These authors have described this chemically induced illness as asthma-like. In individuals diagnosed with RADS, airways hyperactivity (hyperresponsiveness) is a characteristic feature – there is no history of preexisting respiratory illness. Abnormal response or hyperresponsiveness is associated


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with various lung diseases – most notably asthma (Fish and Menkes, 1984). However, it is important to note that there are distinctions between RADS and typical adult-onset asthma. These differences are as follows: (1) RADS is an illness of rapid onset, (2) there is a specific relationship to a single environmental exposure, and (3) the apparent lack of an allergic or immunologic etiology. The mechanism(s) which underpin chemically induced airway hyperresponsiveness is uncertain (Fish and Menkes, 1984; Chan-Yeung and Lam, 1986). To gain a fuller understanding regarding the potential of RCAs to induce RADS, studies (i.e. bronchoprovocation testing) should be conducted in laboratory animals. Despite a wealth of data on the acute effects of RCAs, few studies have undertaken the task to evaluate the acute toxic effects of RCAs in a side-by-side comparison (Ballantyne and Swanston, 1978; Pant and Kumar, 1993; Debarre et al., 1999). In studies by Ballantyne and Swanston (1978), the comparative inhalation toxicity of CS and CN in rats, mice, guinea pigs, and rabbits was studied. Animals were exposed to high concentrations of pure aerosols of CS and CN. None of the animals died during exposure to RCA; however, the majority died during the first two days following exposure. The LCt50 values for the four species exposed to CS were in the range of 50,010 –88,480 mg-min/m3. The LCt50 values for the CN-exposed animals were in the range 8,750 –18,200 mg-min/m3. The LCt50 values for CS were significantly higher than those for CN for each of the species exposed. The lungs of animals dying within the first 48 hours after exposure to CS or CN were congested and edematous, and exhibited multiple variably sized hemorrhages. The trachea was congested and contained rather excessive quantities of mucous. Histopathological examination of the lungs demonstrated moderate to marked congestion of the alveolar capillaries, inter- and intra-alveolar hemorrhaging, and excess secretions in the intrapulmonary bronchi and bronchioles. Occasional areas of collapse beyond occluded bronchioles were noted in some lungs, particularly those from animals exposed to CN. Furthermore, edema was most marked in those animals that died following exposure to CN aerosol. Additionally, following exposure to CN aerosol, patchy acute inflammatory cell infiltration of the bronchioles, bronchi and trachea was noted. Animals dying after 48 hours demonstrated histopathological changes as described here. In some animals, particularly those dying following exposure to CN, liver damage as evidenced by cloudy swelling of the centri-lobular hepatocytes and centrilobular necrosis, was noted. These findings were most noticeable in animals having severe lung damage. Animals surviving the 14 days following CS exposure appeared normal at necropsy and on histological examination of removed tissues. Some of the CN-exposed animals necropsied at 14 days post-exposure manifested patch congestion of the tracheal mucosa and small-scattered pulmonary hemorrhages. The findings support the conclusion that CN is more acutely toxic than CS by the respiratory route. The greater inhalation toxicity of CN compared to CS based on animal studies is consistent with reported cases of human deaths as a result of lung damage following exposure of CN in confined spaces (Gonzales et al., 1954; Stein and Kirwan, 1964). In contrast, there are no authenticated deaths following the use of CS (grenade smoke) (Ballantyne, 1977a). Deaths in humans resulting from exposure to CN in confined spaces follow the same general pattern as seen in experimental animal exposures. Debarre and colleagues (1999) reported their findings on the comparative acute toxicity of CS and OC in rats. In these studies, rats were exposed via inhalation (nose-only) to aerosols of CS (5% solution in methyl isobutyl ketone) or OC (7% solution in solvent). Pulmonary physiology parameters as well as morphological alterations were evaluated. Findings indicated perturbation of respiratory function, as evidenced by a marked reduction in minute ventilation, following exposure to either OC or CS – the reduction in minute ventilation more evident with CS than with OC. In comparison of solvent-induced effects, the reduction of minute ventilation was greater with the CS solvent than with the OC solvent. The time necessary to recover to 80% preexposure minute ventilation was essentially the same for CS and OC. Histological analysis



of the trachea revealed mucous hypersecretion, a common irritant-induced response, following exposure to OC and cytoplasmic vacuoles in the epithelial cells following CS exposure. In the lungs, areas of emphysema were noted following exposure to CS and interstitial edema after exposure to OC. The morphological alterations would indicate more severe effects resulting from CS exposure.

Dibenz[b,f]1:4-oxazepine Ballantyne (1977b) also studied the effects of CR in various animal species following inhalation exposure. Animals were acutely exposed to CR aerosol or CR smoke for varying exposure times and at different concentrations of test article. Rats exposed to CR aerosol at Ct values ranging from 13,050 to 428,400 mg-min/m3 manifested nasal secretions, and blepharospasm (uncontrollable closure of the eyelids), which subsided within one hour on cessation of exposure. Mortalities had not occurred among the CR-exposed rats. In rabbits, guinea pigs, and mice exposed to CR aerosol, no deaths occurred for Ct values up to 68,400 mg-min/m3. Exposure to pyrotechnically generated CR resulted in alveolar capillary congestion and intra-alveolar hemorrhage as well as congestion of the liver and kidneys. The potential of CR aerosol to produce physiological and ultra-structural changes of the lung was studied by Pattle and co-workers (1974). In these studies, rats were exposed to high dosages of CR aerosol (Ct 115,000 mg-min/m3). Electron microscopic examination revealed that organelles (i.e. lamellated osmiophilic bodies) were not altered as a result of exposure to CR. In studies by Colgrave et al. (1979), the effects of high CR aerosol dosages (dosages: 78,200; 140,900; and l61,300 mg-min/m3 ) on the pulmonary system were evaluated. The lungs appeared normal on gross examination; however, microscopic examination revealed mild congestion, hemorrhage, and emphysema. Electron microscopy identified isolated swelling and thickening of the epithelium and early capillary damage as evidenced by ballooning of the endothelium. Colgrave and coworkers concluded that very high doses of CR aerosol produced only minimal pulmonary damage.

Chloroacetophenone Chloroacetophenone, specifically developed an RCA, is a highly potent irritant that elicits acute site-specific toxicity. Although CN primarily acts on the eyes, it will also affect the pulmonary system. At low concentrations, CN produces marked irritation of the nose, throat, and lungs and associated burning and pain sensation. The onset of some or all of these symptoms is immediate. At high concentrations of CN – well beyond the levels that could be generated by typical defense sprays – severe lung and respiratory tract injury can occur. The more severe pulmonary effects are delayed responses, which may take hours to days after exposure to develop. Pathological findings in animals that died after CN aerosol exposures consisted of pulmonary congestion, edema, emphysema, tracheitis, bronchitis, and bronchopneumonia in dogs and pulmonary congestion, edema, bronchopneumonia in rats, mice and guinea pigs (Punte et al., 1962a). The pathology reported by Ballantyne and Swanston (1978) in animals that died after CN inhalation included congestion of the alveolar capillaries, alveolar hemorrhage, and excessive secretion in the bronchi and bronchioles. There were also areas of acute inflammatory cell infiltration of the trachea, bronchi, and bronchioles.

6.3.3 Cutaneous toxicology The ocular and pulmonary systems are critical physiological targets of RCAs, however, the skin is also often involved. The peripheral sensory irritant action of RCAs has been


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previously discussed (see Chapter 5). In this section, the adverse dermal effects, including allergic contact dermatitis, of RCAs are discussed. The dermatoxicity of riot control agents CS, CR, and CN, is discussed. Situations in which adverse skin reactions to RCAs have occurred include: civil, industrial, military, and experimental. Skin damage (i.e. edema, second-degree burn) due to CN or CS results from higher concentrations and /or extended exposure periods. The production of allergic contact dermatitis may result from industrial exposures as well as exposures encountered during civil disturbances. A single exposure may be sufficient to sensitize in some cases, and subsequent outbreaks of dermal lesions may be the result of extremely slight exposures. Among the lacrimatory and RCAs the following compounds are known to cause contact dermatitis: brombenzylcyanide, chloropicrin, CN, and CS.

Chlorobenzylidene malononitrile CS, commonly used in the quelling of riots and other civil disturbances, is a highly irritating compound that elicits injurious action on the skin when topically applied either as a powder or as a solution or on exposure to aerosolized material (Gutentag et al, 1960; Bowers et al., 1960; Weigand, 1969; Rothberg, 1970; Holland and White, 1972; Ballantyne and Swanston, 1978; Zekri et al., 1995). Animal studies were conducted by Ballantyne and Swanston (1978) on the irritative and skin damaging effects of CS (12.5% w/v solution in corn oil or acetone) in various animal species (mice, guinea pigs, and rabbits). Signs of skin irritation (erythema and edema) were evident following topical application of CS. Contrasted with CN, in the same study, areas of inflammation following CS treatment extended little beyond the original area of contamination. The skin reactions were more severe following CN treatment. Histological examination of skin biopsies (3 days after application of CS in acetone revealed foci of epidermal necrosis in the contaminated areas, with acute inflammatory cell infiltration and spongiosis of the outer dermis. In comparison, CN produced extensive necrosis of the epidermis and of the collagen in the outer dermis in the original area of contamination. Edema was evident throughout the dermis and extensive neutrophil infiltration of the dermis was noted. Gutentag et al. (1960) and Bowers et al. (1960) reported the occurrence of erythema and vesiculation in human subjects topically exposed to CS solution or CS powder. Exposure to aerosolized CS, at concentrations equivalent to 300 mg/m3 for a duration of 45 min, resulted in erythema and vesiculation (Hellreich et al., 1967). However, exposure to test article for a duration of 30 min did not produce skin lesions. Studies in human subjects have also indicated that excessive perspiration may contribute to the production of dermal lesions. Weigand (1969) reported findings in which the forearms of volunteers were exposed to suprathreshold concentrations of CS (10,000 and 14,000 mg-min/m3) under ambient conditions of high relative humidity and temperatures. Extreme irritation, erythema, and vesication resulted following exposure to CS at the higher exposure level. Wide individual variations were noted in the cutaneous reactions observed, which depended on the ambient conditions and skin characteristics. Holland and White (1972) compared the dermal response produced by varying amounts of CS or CN (dry and moistened) following topical application to the skin of human subjects. Erythema and transient irritation was noted following application of CS – no vesication occurred. The reactions produced by the moistened material were somewhat more severe. Application of CN resulted in more severe cutaneous reaction than observed with CS. CN produce irritation and erythema and, when moistened, vesication in a significant number of subjects. It was concluded that under comparable conditions, equivalent doses of CN and CS produce cutaneous effects, which were more severe following the application of CN. Workers in a CS manufacturing and processing plant had developed rashes, pruritis, vesicles and wheals, which may have been representative of sensitization and reaction to



re-exposure (Bowers et al., 1960). In animal studies, Rothberg (1970) confirmed that both CS and CN could produce skin sensitization in guinea pigs when administered topically and intra-dermally. In another study on occupational hazards involving CS manufacture, Shmunes and Taylor (1973) attempted to characterize the magnitude of cutaneous hazards stemming from the industrial preparation of CS. Male employees were questioned about dermatological complications during their employment. They were examined by a dermatologist and patch-tested to solutions of CS. Findings from these studies indicated a significant sensitizing potential in what was described as an open system for handling CS. Aside from the Himsworth reports (Himsworth et al., 1969; Himsworth, 1971), which focused on the toxicological/medical aspects of CS following its use in Londonderry, and a study by Fuchs and in der Wiesche (1990), the literature is devoid of studies/reports addressing symptomatology, the frequency and circumstances of irritant exposure, and treatment measures among demonstrators exposed to RCAs. Fuchs and in der Wiesche (1990) reported on the incidence of contact dermatitis among demonstrators that experienced multiple exposures to either CN or CS or both RCAs. Exposure to RCAs followed dissemination via irritant spray devices (RCA concentrations: CN (0.9%); CS (1%) ) or water projectors (RCA concentration ~0.03%). A significant number of subjects (38/56) were subjected to both CN as well as CS. An excess of one-third of the subjects had been subjected to five or less incidents of irritant material; however, a large percentage of study subjects reported exposure episodes of up to fifty. Epicutaneous tests (patch testing) were conducted and test reactions evaluated. Skin symptoms were reported in over 50% of the individuals exposed and positive test reactions (~20%) to CS and CN were observed. The subject of cross-reactivity was also addressed. Although cross-reactivity between CN and CS reported by Maibach and Marzulli (1971) has not been confirmed, animal experiments (Chung and Giles, 1972) indicated cross-reactivity in CN-sensitized guinea pigs. Fuchs and in der Wiesche concluded that sensitization to related compounds could not be completely excluded in the test subjects.

Dibenz[b,f]1:4-oxazepine Dibenz[b,f]1:4-oxazepine interacts locally with receptor sites on cutaneous nerves producing at the site of contamination an intense irritation and pain. Applied to the skin, CR produces a mild erythema of relatively short duration. Histological analysis of skin obtained from animals 14 days after the dermal application of CR indicated normal, healthy tissue. This contrasts with the adverse skin reactions (e.g. inflammatory reaction, second-degree burns, vesication) following the application of CS or CN. A number of dermal toxicity studies in animals and humans, including repeated-dose, have been conducted on CR as neat material or in solution (Biskup et al., 1975; Holland, 1974; Marrs et al., 1982). Biskup and co-workers (1975) examined the effects of CR (1% in polyethylene glycol) in rabbits after cutaneous administration of single and multiple doses of CR solution. No signs of irritation (e.g. erythema and edema) were noted following a single dose of CR. Likewise, repeated doses of CR solution did not result in skin injury. Microscopic evaluation revealed no alterations in skin morphology. A repeated-dose dermal toxicity of CR was conducted by Marrs et al. (1982). In these studies, CR in acetone was applied to the skin of mice 5 days/week for 12 weeks, and mice of all groups were maintained for an additional 80 weeks. Based on the findings, it was concluded that the repeated dermal application of CR solution had minimal effect on the skin. Holland (1974) evaluated in human subjects skin reactions to CR applied as a dry or wetted powder. Erythema appeared in ten minutes and subsided approximately 30 min following removal of CR. Swelling or vesication had not developed and no residual skin changes were seen. In comparing these results with those of similar tests with riot control


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agents CN and CS, Holland reiterated the notion that the dermal response to CR are transient and less severe than the skin reactions observed following the administration of CN or CS.

Chloroacetophenone Exposure to CN in aerosol, liquid, or solid form has been associated with both primary and allergic contact dermatitis (Ingram, 1942; Kissen and Mazer, 1944; Penneys et al., 1969; Penneys, 1971; Holland and White, 1972; Chung and Giles, 1972). Like CS, CN is a potent irritant producing similar effects on the skin; however, CN is more likely than CS to produce both primary and allergic contact dermatitis. The severity of actions varies according to the amount of CN, the duration of contact, and the condition of the skin (i.e. moist or dry). Additionally, it is possible for individuals to be sensitized to CN with crossover reactions to CS (Hu, 1992). Seminal studies conducted by Vedder (1925) demonstrated that exposure to high concentrations of CN vapor resulted in erythema and vesication. The cutaneous reactions after single and multiple exposures to CN vapors have been described (Queen and Stander, 1941; Kissen and Mazer, 1944; Madden, 1951). Ingram (1942) reported the occurrence of irritation, erythema, and blistering after exposure to high concentrations in confined spaces. Holland and White (1972) compared the dermal irritant actions of CS and CN in human subjects when applied to the skin. As stated in the discussion on the dermal effects of CS, the skin reactions following application of CN were of greater severity than observed following CS application. In a comparative study on the effects of CN and CS, Ballantyne and Swanston (1978) evaluated the effects of these RCAs on rabbit, guinea pig, and mouse skin. Their findings indicated that the CN-induced cutaneous effects were of greater severity than the cutaneous reactions produced after application of CS.

6.3.4 Immunotoxicology The toxicological effects of RCAs, in particular that of CN and CS, may also involve the immune system. Interest in the immunosuppressive potential of RCAs stems from the putative alkylating properties of CS and CN. Many alkylating compounds have been reported to be immunosuppressive owing to their action(s) on macromolecular moieties such as nucleic acids (Bach, 1975).

Chlorobenzylidene malononitrile Nagarkatti and Nagarkatti (1979, 1981) and Nagarkatti et al. (1981) conducted studies in mice seeking to establish a relationship between CS exposure and altered immune function. Initial studies demonstrated that the antibody response to thymus-dependent antigen was depressed in CS-treated mice. Indications that CS also affected B lymphocyte functions following CS treatment was demonstrated in studies (Nagarkatti and Nagarkatti, 1981) on the humoral immune response to bacterial lipopolysaccharide (LPS), a thymus-independent antigen. Immunosuppression may be secondary – a consequence of nutritional perturbations and/or endocrine imbalance (Vos, 1977). Nagarkatti et al. (1981) conducted studies to determine whether the effects of CS on the immune system were primary or secondary in nature. In these studies, mice were treated with CS at two dose levels to ascertain the effect of CS on immune function. CS treatment resulted in suppression of the humoral immune response to the heterologous antigen (sheep red blood cells, SRBC), and at the higher dose level additionally produced an increase in corticosterone levels. The authors concluded that CS directly affected the immune system, as evidenced by the suppression of humoral immunity to antigen at lower doses.



Chloroacetophenone As an alkylating agent, CN has the potential to cause alterations in the immune response. Acute mammalian toxicity studies have suggested the possible involvement of the immune system; however, the precise effects of CN on the immune system have been inadequately studied. It was not until studies by Kumar et al. (1993), that findings indicated a relationship between exposure to CN and alteration of the immune response. These authors studied the effects of inhaled CN vapor on the pulmonary immune response – more precisely the effect of CN on phagocytic potential of pulmonary macrophages. Macrophages play an important role in the pulmonary immune system, and alteration in their function serves as sensitive indicator of chemically induced perturbations. Mice were exposed to CN vapor (~0.5 mg/L) under static conditions for a period of 15 min followed by bioassay of the phagocytic capacity of pulmonary alveolar macrophages. Phagocytosis of Saccharomyces cerviceae by macrophages decreased significantly following CN exposure as compared to controls. These findings are suggestive of immune function alteration by CN. The suppressed phagocytic capability of pulmonary immunocompetent cells may have implications beyond the immediate peripheral sensory irritant effects and pharmacological actions of these compounds.

6.3.5 Endocrine toxicology Xenobiotics can affect the endocrine system of animals – all components (glands, tissues, receptors, transport proteins, and enzymes) of the endocrine system are targets for toxicity. Furthermore, endocrine disruption may also be considered a mechanism. Primary toxicity may involve direct action(s) on the endocrine organs (pituitary, thyroid, parathyroid, adrenal, ovary, testis, and pancreas). Additionally, the endocrine system is affected via secondary mechanisms in toxicity to the liver, kidney, nervous, immune, cardiovascular, gastrointestinal, and female and male reproductive systems – for reviews refer to Harvey et al. (1999). Physical stresses including exposure to irritant substances can elicit alterations in endocrine function and endocrine gland morphology. RCAs are potent stressors and are capable of producing secondary effects involving the adrenals and thyroids. The adrenals, which are glands of considerable importance as both a toxicological target and a modulator of toxicity (Harvey, 1996), are also involved in reproductive function, growth, and development. It is well known that the biochemical response of the adrenals to any stressor is the increased secretion of catecholamines and glucocorticoids. Furthermore, histological changes of the adrenals under both acute and chronic stress have been documented. Chowdhury et al. (1978a) studied the effect of acute administration of CS on adrenal morphology. Gross examination revealed hypertrophy of the adrenals in the treated animals. Microscopic evaluation indicated hypertrophic alterations in the cells of both the cortical and medullary areas of the adrenals of CS-treated animals. The cells of the zona fasciculata of the treated groups were distorted with hyalinated cytoplasm and pyknotic nuclei. Nuclei of the medullary cells were vesicular and enlarged. Cytometric analysis indicated a marked increase in the cell nuclear diameter of both the cortex and medulla following administration of the high dose. The sharp rise in cell nuclear diameter of medullary cells following CS treatment may have been closely associated with the hypersecretion of catecholamines. Cellular change in the cells of the cortex may also be associated with the increased secretion of glucocorticoids. Secondary effects of RCAs may also involve the thyroid. It is well documented that physical stressors (e.g. irritating substances, hemorrhage, and trauma) induce a prompt and prolonged inhibition of thyroid secretion, presumably as a consequence of diminished release of thyroid stimulating hormone (TSH) (Turner, 1964). The histological changes


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of the thyroid during acute and chronic stress have been discussed by Brown-Grant et al. (1954). The effect of acute exposure to CS on the thyroid gland was studied by Chowdhury et al. (1978b) following the i.p. administration of sublethal doses of CS. Histological analysis of the thyroids revealed minor degenerative changes of the thyroid follicle at a dosage of 10 mg/kg. At the higher dosage of 20 mg/kg, complete degeneration of the thyroid follicle was noted. The degenerative changes elicited by CS may also be the result of the continuous inhibition of TSH secretion leading to the atrophy of the thyroid follicles; however, Chowdhury et al. also postulated that a direct toxic action on the thyroid by CS cannot be ruled out.

6.4

TOXICOLOGY OF RCA FORMULATIONS

Individuals are presented with multiple chemical exposure in the use and application of RCAs whether the exposure is the result of dissemination via pyrotechnic devices or by personal defense spray products. Rarely is human exposure to xenobiotics limited to a single chemical, yet the vast bulk (~95%) of toxicological databases has been derived from single chemical studies. The limited toxicological database on mixtures/formulations is likewise shared by RCAs – few studies have adequately addressed the toxicological characteristics of RCA formulations. Recently, public and regulatory concerns have escalated over multiple chemical exposures and have driven the need for integrative approaches in the assessment of chemical mixtures toxicity. The paramount issue concerning health effects of chemical exposure, including exposure to RCAs, is exposure to chemical mixtures and the resulting health consequences. Historically, toxicity evaluation of chemical mixtures has focused on mixtures containing relatively few components or on specific interaction studies. Overall, exposure and toxicity data for most chemical mixtures are fragmentary, and conventional toxicity testing approaches are inadequate in addressing chemical mixture issues. The National Research Council of the NAS and the US EPA have addressed the issues, concerns, and approaches related to the toxicity assessment of chemical mixtures (NAS, 1988; EPA, 1990). In the industrial toxicology sector, a number of studies have addressed the mixture toxicology issue; for example, several investigators have conducted studies to evaluate the toxicity of a combination of chemicals of up to nine components (Jonker et al., 1990, 1993; Groten et al., 1994). Whole mixture toxicity testing of highly complex mixtures, containing numerous chemicals (e.g. diesel exhaust and other emissions) have also been performed. The general consensus within the scientific and regulatory communities is that the systematic in vivo toxicity testing of complex chemical mixtures is impractical and unattainable because of the large numbers of combinations involved, ethical, economic, and resource considerations. A considerable number of RCA formulations, as liquid formulations in spray canisters or as powder formulation devices, have been developed for law enforcement and personal protective use. The riot control agents CN, CS, CR, and OC are formulated as solvent-propellant mixtures (refer Appendix C). Some defense spray formulations may contain OC in combination with either CN or CS as the active ingredients. In general, personal defense spray formulations are relatively simple mixtures with the exception of OC sprays, since OC contains numerous compounds. Pyrotechnic mixtures (“irritant smokes”), containing RCA (CN or CS), potassium chlorate, lactose, and kaolin – have been developed for use in civil disturbances. A number of studies have addressed, in varying degrees, the pharmacological/ toxicological characteristics of RCA formulations (self-defense spray): CS (Ballantyne, 1979); CN (Gaskins et al., 1972); and “pepper spray” (Lee et al., 1996; Zollman et al., 2000). Gaskins et al. (1972) evaluated 25 commercial aerosol formulations containing CN for



ocular effects. As discussed previously (Section on ophthalmic toxicology), commercial formulations which contained CN at concentrations between 0.04% and 1.0% produced transient ocular effects. In the same study, a limited number of rabbits were exposed to very high concentrations of aerosolized “Chemical Mace” in a static inhalation chamber. Animals exhibited moderate inflammation of the conjunctivae, but no damage to the cornea. Effects on the respiratory system were not evaluated. Marked cutaneous injury was noted following exposure to suprathreshold levels of CN. Ballantyne (1979) studied the ocular effects of a CS formulation (10% w/v CS, dichloromethane, dichlorodifluoromethane), frequently used in defense spray aerosols. As discussed previously in the section on ophthalmic toxicology, the close-range discharge of CS from an aerosolized canister resulted in inflammation of the eyes and keratitis. The effects of OC (“pepper spray”) formulations on human subjects were studied by Lee et al. (1996) and Zollman et al. (2000). The focus of these studies was to ascertain the effects of commercially available OC defense sprays on the eye. Physiological effects on other potential target organs such as the respiratory system was not evaluated. Exposure to “pepper spray” resulted in marked lacrimation, intense blepharospasm – acute effects persisted for about ten minutes, with relatively complete recovery in about 60 min from cessation of exposure (refer Chapter 7 for a more detailed discussion).

6.5 THERMAL DEGRADATION PRODUCTS OF RCAs It is well known that thermal decomposition of a material may produce a wide range of lower molecular weight species of varying toxicity. Furthermore, the number, nature, and relative proportions of the products depend on the material undergoing thermal decomposition and ambient conditions. The potential adverse effects of products resulting from the thermal decomposition of a material include irritant effects, incapacitation, systemic toxicity, pulmonary injury, and death. The pyrotechnic dispersion of RCAs can produce a variety of inorganic and organic decomposition products with the potential of inducing toxic effects. Historically, a number of animal studies have been conducted to ascertain the biological effects of pyrotechnically generated CS or CN; however, these studies focused on the RCA alone and had not considered the potential contribution of thermal degradation products to the overall toxicity associated with the thermal dispersion. Likewise, previous studies to assess the human health effects of pyrotechnically generated CS have focused on CS alone and not accounting for CS-derived thermal degradation products (Punte et al., 1963; Weigand, 1969; Beswick et al., 1972; Holland and White, 1972). An end to the hiatus in the interest and research related to degradation products from thermally generated RCAs is largely the result of recent work by Kluchinsky and co-workers (Kluchinsky et al., 2001, 2002a,b). Renewed interest in RCA degradation products has led to a number of recent publications on the detection and identification of CS thermal degradation products. Moreover, from the perspective of risk assessment/risk characterization, the identification of compounds of concern is a critical component of the risk assessment/risk characterization process along with exposure assessment and toxicity assessment. The findings from earlier studies along with the recent work of Kluchinsky et al. (2001, 2002b) on the formation of CS-thermal degradation products, as well as, the study by Kluchinsky et al. (2002a) on the generation of HCN following hightemperature dissemination of CS are synopsized next. The toxicology and implications of CS-derived degradation products are also discussed. Ballantyne and Callaway (1972) in their evaluation of the toxic effects of pyrotechnically dispersed CS had only mentioned the potential for pyrotechnic decomposition products formation. The focus of their efforts was directed towards CS and not on the detection and identification of CS degradation/combustion products nor on the toxicology or


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health implications of pyrotechnically disseminated CS. Organic CS-derived compounds may be formed as a result of the pyrolytic decomposition of CS. The degradation products from the high temperature dissemination of CS are produced via the rearrangement and/or loss of cyano and chlorine moieties of the CS molecule. Kluchinsky et al. (2001) identified airborne CS degradation products pyrotechnically dispersed from canisters of a type used by law enforcement personnel. The CS canisters contain a mixture of CS, potassium chlorate, magnesium carbonate, nitrocellulose, and an unspecified sugar. Degradation products were collected on sampling filters, extracted, and analyzed via gas chromatography/mass spectrometry. About 20 CS-derived compounds were detected and identified. Major degradation products detected and identified were cyanocinnamonitriles (2-, 3-, and 4-), 2-chlorobenzaldehyde, 3-(2-chlorophenyl) propynenitrile, 3-quinoline carbonitrile, and 3-isoquinoline carbonitrile. Minor degradation products included 2,2-dicyano-3-(2-chlorophenyl) oxirane, also known as CS epoxide, and dihydro-CS. A CS isomer, identified as 4-chlorobenzylidene malononitrile, was a bi-product of the synthesis of CS and not a pyrolysis product. Some of these degradation products may have toxic characteristics. Subsequent studies by Kluchinsky and co-workers (Kluchinsky et al., 2002b) on thermal degradation products of CS from discharged CS canisters or from tube furnace experiments, have confirmed earlier results. The latter studies demonstrated that CS-derived thermal degradation products such as 2-cyanocinnamonitrile are not formed at temperatures of 300–500C, whereas such decomposition products are generated at higher temperatures (i.e. 700–900C). Furthermore, the results also indicated that at lower temperatures, little or no formation of 3-(2-chlorophenyl) propynenitrile occurs – consequently a minimal release of HCN. The collective results from these studies have implications not only for health risk assessment but also for the future development of safer RCA thermal devices. From the risk perspective, the findings suggest that the risks posed to the general public and to law enforcement personnel from the use of CS disseminated from pyrotechnic devices should be reevaluated. This is critically important when taking into consideration the utilization of thermally generated CS in enclosed spaces. Moreover, these results suggest the need to develop CS canisters that would discharge at reduced temperatures resulting in a lower likelihood of generating toxic CS degradation products. A degradation product of concern following the pyrotechnic dissemination of CS is HCN. Any material containing carbon and nitrogen will liberate HCN under appropriate thermal/combustion conditions. HCN may be generated in sufficient amounts to produce physical incapacitation and other adverse biological effects. For many compounds, particularly from nitrogen-containing polymers, thermal decomposition may produce sufficient amounts of HCN to produce physical incapacitation or lethality. In further studies on CS-derived degradation products, Kluchinsky et al. (2002b) confirmed the seminal studies by Porter et al. (1961) and subsequent studies on the formation of HCN following high temperature dispersion of CS. The toxicity and implications on the liberation of HCN as a result of the pyrotechnic dissemination of CS has been discussed in a previous section.

6.6 TOXICOLOGY OF RCA CARRIERS/SOLVENTS Owing to their poor water solubility, RCAs used in defense sprays are formulated with solvents/carriers. An array of solvents are currently utilized or have been used in RCA formulations including dichloromethane, methyl isobutyl ketone, trichloroethane, isopropyl alcohol, glycols, and kerosene hydrocarbons (refer Table 6.4 and Appendix C for an expanded listing of carriers/solvents used in RCA formulations). Also, various solvents such as trioctyl phosphate, which are not typically found in commercial preparations,



have been utilized in the toxicological assessment of RCAs. A solvent may be a suitable carrier for more than one RCA, as in the case of dichloromethane or have limited application such as propylene glycol, which is utilized as a co-solvent in CR formulations. In the past, kerosene hydrocarbons were even utilized as the vehicle in CN formulations. Modern-day defense spray formulations use either dichloromethane or methyl isobutyl ketone as a carrier for CS and isopropyl alcohol for defense sprays containing OC. Very recently developed defense sprays containing nonivamide (“synthetic capsaicin”) utilize a co-solvent mixture containing water and ethanol. The solvent/carrier keeps the active ingredient in an appropriate state for aerosol dispensing. It may also contribute to the effectiveness of the spray by improving penetration or prolong contact time. However, from the health hazard and environmental aspects, solvents may contribute to unwanted effects such as isopropanol-induced ocular injury (i.e. corneal erosion), methyl isobutyl ketone-related skin injury (i.e. blistering), and dichloromethane-induced neurotoxic effects. Of additional note related to solvent toxicity, one must recognize the contribution of impurities and additives to the overall toxicity associated with a particular solvent. Impurity or additive-related toxicity may be avoided or reduced by the elimination or reduction in the quantity of a particular impurity or the reduction in the amount of an additive. Ideally, the solvent/carrier should have a low-order of toxicity, devoid of long-term effects, devoid of reproductive/teratologic effects, nongenotoxic, and noncarcinogenic. Despite some inroads in the development and use of solvents that pose fewer health and environmental risks, solvents have not been developed that are entirely devoid of health hazards. As in the past, solvents for personal defense sprays or for riot control purposes are those generally available for various consumer products. On exposure to defense sprays, the acute health effects stemming from exposure to potentially high concentrations of solvent, particularly in poorly ventilated areas, are cause for

TABLE 6.4 Carriers and propellants currently or formerly used in defense (“incapacitant”) spray formulations RCA

Solvents/co-solvents

Propellants

CS

Dichloromethane, methyl isobutyl ketone, trichloroethane, trichloroethane/polyethylene glycol Propylene glycol/water, polyethylene glycol/water Kerosene hydrocarbons/ trichloroethane Isopropyl alcohol, ethanol/propylene glycol

Dichlorodifluoromethane, nitrogen

CRa CN OC

Nonivamide (“synthetic capsaicin”)

Water/ethanol

(—)b Freon 113c Dymel 134a/P “praxair”, isobutane/propane (—)d

Notes a Defense spray formulations containing CR have not been developed for law enforcement or civilian use. b Dissemination devices do not employ propellants. c Freon 113 (1,1,2-trichloro-1,2,2- trifluoroethane). d Propellant not identified by manufacturer.


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additional concern from the perspective of medical management following exposure to the dispersed ingredients from these devices. The toxicity of a solvent is dependent in large measure on the route of exposure, the severity of exposure, and the chronicity of exposure. Also, in some cases, the toxicity of a solvent may be associated with impurities and additives (i.e. stabilizers). Generally, the level of acceptable impurities is dependent on use patterns – purer grades are utilized for aerosol, food extraction, and reagents. Solvent additives are usually added in small amounts. Solvents can produce acute, subchronic, and chronic effects – the acute effects tend to resolve soon after discontinuation of the exposure. The toxicological effects common to most solvents are associated with their irritative action on the mucous membranes, their effects on the skin, and the depression of CNS function. Most solvents irritate the mucous membranes of the eyes, nose, and throat – the eyes being the most sensitive. The initial manifestation is typically a burning sensation – heavy exposures are commonly manifested by loss of breath, cough, and chest tightness. Strong irritant solvents (e.g. acrolein and formaldehyde) can induce symptoms at low exposure levels while at high concentrations common solvents (e.g. dichloromethane and toluene) can result in pulmonary edema and chemical pneumonitis. Pertaining to CNS effects, short-term exposure to organic solvents produces neurotoxic effects that are reversible after termination of exposure. Prolonged exposure; however, is associated with neurophysiological/ neuropsychological impairment. Distinct from general effects are specific toxic effects, which are often related to the metabolism of the solvent. The toxicity characteristics of solvents/carriers that are or were commonly used in defense spray formulations are summarized in Table 6.5. Although a detailed discussion on the toxicology of solvents commonly used in RCA formulations is beyond the scope of this chapter, a brief synopsis on the toxicology of some of these solvents/carriers is presented. The reader is referred to the following reviews, chapters, and books pertaining to solvent toxicology (Craft, 1983; Gad and Chengelis, 1988; Tahti et al., 1999).

6.6.1 Dichloromethane Acute and repeated-dose toxicity Dichloromethane, also known as methylene chloride, is available as technical grade and grades intended for aerosol use, food technology, and reagent use. It is extensively used as an industrial solvent, as a solvent in aerosol products, and as a common ingredient in paint removers. Dichloromethane is also widely used as a solvent in RCA formulations. Methylene chloride is considered relatively nontoxic except at very high exposure levels, which may occur readily in poorly ventilated areas resulting in serious adverse effects. Acute exposure results in mucous membrane and respiratory tract irritation, and at high concentrations narcosis, CNS depression, and respiratory failure (Von Oettingen, 1964). Liver and kidney damage may also be associated with exposure to high levels of dichloromethane (Heppel et al., 1944; Klaassen and Plaa, 1966; Plaa, 1973). Exposure to dichloromethane vapor causes eye irritation, and direct contact with the liquid form may cause burns to the cornea. Toxicological hazard from exposure to dichloromethane also stems from the in vivo formation of carbon monoxide (CO) during the course of dichloromethane metabolism. For reviews on the health effects and toxicology, refer to the EPA health assessment on methylene chloride (EPA, 1984), the ATSDR toxicological profile for methylene chloride (ATSDR, 1998), and papers by Aviado et al. (1977) and Long et al. (1994). Ballantyne et al. (1976b) reported that instillation of dichloromethane into rabbits’ eyes resulted in copious lacrimation, inflammation of the lids and conjunctivae, conjunctival edema, iritis, keratitis, and increased intraocular pressure. In the same


TABLE 6.5 Toxicity characteristics of representative solvents/carriers used in self defense (“incapacitant”) spray formulations Solvent/carrier

Acute toxicity LD50 (mg/kg)

Target organ(s)

Irritation ocular/dermal

Developmental/ reproductive toxicity

Carcinogenicity/ mutagenicitya

LC50 (mg/m3)

Dichloromethane (Methylene chloride)

2,100

49,100

CNS, lung, liver

(pos)/(pos)

(neg)/(neg)

(pos)/(pos)

Methyl isobutyl Ketone Isopropyl alcohol 1,1,1-trichloroethane

2,671 5,840 11,240

23,000 (#)c 3,320

(pos)/(pos) (pos)/(pos) (pos)/(pos)

(pos)/(neg) (pos)/(pos) (neg)/(neg)

(neg)/(—)b (neg)/(neg) (pos)/(neg)

20,000 28,915

(—)b (#)d

CNS CNS CNS, cardiovascular CNS Liver, kidney

(pos)/(pos) (pos)/(pos)

(pos)/(pos) (—)/(neg)

(neg)/(neg) (neg)/(neg)

Propylene glycol Polyethylene glycol (i.e. PEG-400)

Notes a Microbial and mammalian mutagenesis assay systems. b No data. c LCLo 32,400 mg/m3 (12,000 ppm). d LCt50 for PEG 500 reported as 900,000 mg-min/m3; toxicity of PEG 400 is similar.


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studies, exposure to dichloromethane vapors resulted in increased corneal thickness. Case reports indicate that dichloromethane can cause eye and skin damage following direct contact with the liquid (Hall and Rumack, 1990). The CNS is a target for both short-term and long-term inhalation exposure. In common with other low-molecular weight halogenated hydrocarbons, dichloromethane is a CNS depressant (Savolainen et al., 1977; Savolainen et al., 1981). Available data indicate that the CNS is the primary target organ of inhaled dichloromethane in humans and animals (Fodor and Winneke, 1971; Stewart et al., 1972; Winneke, 1974; Savolainen et al., 1981; Rebert et al., 1989). In humans, neurotoxic effects of methylene chloride exposure include: dizziness, headache, nausea, tingling, memory loss, parathesis, and loss of consciousness. Severe or prolonged exposure may lead to respiratory depression and death. If high carboxyhemoglobin levels are present, the symptoms of acute CO poisoning may also occur. Animal data indicate that repeated exposure to dichloromethane via inhalation produces CNS effects (Savolainen et al., 1981; Briving et al., 1986; Rosengren et al., 1986; Karlsson et al., 1987), liver effects (Haun et al., 1972; Kjellstrand et al., 1986), and kidney effects (Haun et al., 1972). In regard to CNS effects; for example, methylene chloride has been studied in animals for its ability to produce neurochemical, neurophysiological, and neuropathological alterations following intermediate duration exposure. Neurochemical changes in animals following repeated-dose exposure to methylene chloride have been reported (Briving et al., 1986; Karlsson et al., 1987). However, intermediate-duration exposure to methylene chloride did not result in neurobehavioral or neurophysiological deficits or in neuropathological effects (Bornschein et al., 1980; Mattsson et al., 1990).

Disposition and metabolism Dichloromethane may be absorbed following inhalation or dermal exposure. Once absorbed, the major sites of distribution are the brain, liver, and fatty tissue. This compound possesses a short biological half-life, and dichloromethane-induced toxic effects for the most part are readily reversible. The metabolism of dichloromethane has been extensively studied (Kubic et al., 1974; Kubic and Anders, 1975, 1978; Ahmed and Anders, 1976, 1978; Gargas et al., 1986; Green et al., 1988; Reitz et al., 1989; Reitz, 1990; Casanova et al., 1992, 1997; Bogaards et al., 1993; Green, 1997). Following inhalation, dichloromethane undergoes hepatic as well as extrahepatic bioconversion. The major metabolites of dichloromethane are CO2 and CO found in expired air. Both microsomal (MFO) and non-microsomal (GST) pathways participate in the bioconversion of dichoromethane. Metabolism to CO is mediated via the microsomal cytochrome P-450 pathway (specific isoenzyme: cytochrome CYP2E1) and nonmicrosomal bioconversion to CO2 via a pathway involving glutathione transferase (specific isoenzyme: theta-class (GSTT1-1). The glutathione pathway metabolizes dichloromethane to CO2 following the formation of both formaldehyde and a glutathione conjugate, putatively chloromethyl glutathione. Related to CO2 formation, Gargas et al. (1986) had postulated that CO2 could also be produced by the MFO pathway involving the reactive intermediate formyl chloride. The MFO pathway is a high affinity, low capacity pathway (saturable at about 500 ppm of dichloromethane), whereas the GST pathway is a low affinity, high capacity pathway (no indication of saturation even at very high concentrations (i.e. ~10,000 ppm) of dichloromethane). Since dichloromethane is metabolized in part to CO elevations in carboxyhemoglobin (COHb) may result (Stewart et al., 1972). COHb formation as a result of the metabolic conversion of dichloromethane to CO has been reported to be saturable in both humans (McKenna et al., 1980) and laboratory animals (Hogan et al., 1976; McKenna and Zempel, 1981; McKenna et al., 1982). The formation of COHb produces a shift in the oxyhemoglobin dissociation curve, theoretically resulting in a diminished ability to release oxygen at the tissue level. Species differences are evident in metabolic pathway preference – the



glutathione pathway is more active in experimental animals. Comparatively, the GST pathway is a relatively inactive bioconversion route in humans. This metabolic difference has considerable implications as related to carcinogenic potential. It is generally accepted that the known carcinogenicity in animals correlates with dichloromethane metabolism via the glutathione metabolic pathway but not the cytochrome P-450 pathway. Although, the relative inactivity of the glutathione pathway in humans suggests a low risk of dichloromethane-induced genotoxicity/carcinogenicity, recent findings by Sherratt et al. (1997) suggest that humans may possess a low capacity for converting methylene chloride into reactive metabolites via glutathione S-transferase activity.

Mutagenicity, carcinogenicity, and developmental/ reproductive effects The genotoxic effects of methylene chloride have been evaluated in microbial and mammalian assays (Gocke et al., 1981; Jongen et al., 1981; Thilagar et al., 1984; Green et al., 1988; Raje et al., 1988; Allen et al., 1990). In vitro results were mixed in bacterial assays as well as in assays which utilized mammalian cells. Equivocal results were obtained from the in vivo assay systems in animals. Oncogenicity studies via various routes of exposure have been conducted in a number of animal species to assess the carcinogenic potential of dichloromethane (Burek et al., 1984; NTP, 1986; Serota et al., 1986a,b; Mennar et al., 1988; Nitschke et al., 1988a). In rodent studies, inhalation of very high concentrations of dichloromethane resulted in an increased incidence of pulmonary and hepatic tumors (NTP, 1986; Mennar et al., 1988). Burek et al. (1984) studied the carcinogenic potential of dichloromethane in rats and hamsters following inhalation exposure. Animals were exposed for 6 h/day, 5 days/week for 2 years to 0, 500, 1,500, or 3,500 ppm of dichloromethane. Noncancer dichloromethaneinduced alterations consisted of an increased incidence of hepatocellular vacuolization. Liver lesions were initially noted after 12 months and were more pronounced after 18 months. An increased number of benign mammary tumors were also noted on longterm exposure to methylene chloride. There was no indication of a carcinogenic response in hamsters following exposure to dichloromethane. A carcinogenesis bioassay to ascertain the cancer-inducing potential of dichloromethane was conducted under the US National Toxicology Program (NTP, 1986). Findings in rats exposed to dichloromethane were concordant with those reported previously by Burek and colleagues – namely an increased incidence of benign mammary tumors. Mice exposed to methylene chloride in the NTP study exhibited increased rates of lung and liver neoplasms as well as liver toxicity. Nitschke et al. (1988a) conducted a chronic study in rats to assess the effects of inhaled methylene chloride at exposure levels of 0, 50, 200, or 500 ppm. The levels of dichloromethane were considerably lower than those in the Burek et al. study to include an exposure level near a dosage that results in saturation of the mixed function oxidase metabolism of dichloromethane. Exposure-related histopathologic changes were limited to the liver and mammary glands of female rats exposed to 500 ppm of dichloromethane. Findings also revealed an increased incidence of hepatocellular vacuolization. Nitschke et al. concluded that long-term administration of methylene chloride to rats and mice did not produce a neoplastic response in either species. The carcinogenic potential of dichloromethane via non-inhalation exposure was studied in mice and rats by Serota et al. (1986a,b). Liver tumors were observed in female rats following ingestion of methylene chloride; however, the incidence rates were within control ranges. Hepatic tumors were observed in male mice; however, the increased incidence was not statistically significant. Female mice did not have increased liver tumor incidence. The US EPA (1985a,b, 1987a) has reviewed the data on the carcinogenic effects of dichloromethane and concluded that there was borderline evidence for carcinogenicity.


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Methylene chloride crosses the placental barrier (Anders and Sunram, 1982), and studies (Schwetz et al., 1975) suggest an increase in the incidence of minor skeletal malformations. Teratogenic effects were not observed following exposure to methylene chloride (Bornschein et al., 1980). Results from two generation reproductive studies indicate nil effects on reproductive function (Nitschke et al., 1988b). Data on the reproductive toxicity of methylene chloride to humans is limited and the practical import of the few published studies is reduced because of the small number of subjects evaluated and lack of concurrent controls. For more in-depth discussion on the developmental/reproductive aspects, refer to Chapter 9 by Mankes and Mankes and the review by Wiger (1991).

6.6.2 Methyl isobutyl ketone Acute and repeated-dose toxicity Methyl isobutyl ketone (MIBK, 4-methyl-2-pentanone) is a clear, colorless liquid that is moderately soluble in water that is used as a solvent in RCA formulations. MIBK occurs naturally in foods, is a permitted flavoring agent, as an extractant, and is widely used as a solvent for paints, lacquers, varnishes, and adhesives. The major health hazard stems from inhalation exposure; however, skin and eye contact can also be hazardous. Typical of many solvents, MIBK produces CNS effects, irritation of the mucous membranes, eyes, and the skin. Targets for MIBK toxicity include the mucous membranes, the CNS, GI tract, liver, and kidneys. Vapors of MIBK can irritate the eyes – splashes can cause severe pain and irritation. Skin contact with MIBK can result in dermatitis. The irritative effects in human subjects exposed to MIBK vapor have been described by Hjelm et al. (1990). Animal studies suggest that the acute systemic toxicity of MIBK via the oral and inhalation routes of exposure is low – for mice the LC50 estimate is 23,000 mg/m3 (5510 ppm). Animal studies (Specht et al., 1940; Smyth et al., 1951; Krasavage et al., 1982) have indicated that at high concentrations, MIBK is a CNS depressant. Evidence of CNS depression was noted in animals exposed to a concentration of 4100 mg/m3 (1000 ppm). However, Linari et al. (1964) and Hjelm et al. (1990) have reported that human exposure to low concentrations of MIBK has resulted in CNS effects. The major route of exposure in humans is via inhalation. Occupational exposure to MIBK occurs – particularly in the production and use of paints, lacquers, and extraction solvents. The general population is exposed to low levels of methyl isobutyl ketone. The use of law enforcement defense sprays, containing MIBK as an ingredient, provides an avenue of exposure to this material and may present a certain degree of health risk. The low odor threshold (1.65 mg/m3 (0.4 ppm) ) and irritant effects of MIBK can provide warning of high concentrations – as in the case of RCAs and other potent peripheral sensory irritants. Exposure to MIBK levels of 10–410 mg/m3 (2.4–100 ppm) produces perceptible irritation of the eyes, nose, or throat. Gastrointestinal distress and pain as well as hepatic toxicity may occur following exposure to high concentrations of MIBK. The irritative effects of MIBK on the eyes and mucous membranes in humans have been described by Hjelm et al. (1990). Exposure to methyl isobutyl ketone has been reported to cause dermatitis (Linari et al., 1964). Multiple exposure studies suggest target organ toxicity involving the liver and kidneys. Rats exposed to 100–200 ppm of MIBK for two weeks manifested toxic nephrosis (nephritis) and increased liver weights; however, no adverse effects were noted in mice, dogs, and monkeys similarly exposed to MIBK (MacEwen et al., 1971). A study to assess the subchronic toxicity of MIBK was conducted by Phillips et al. (1987). Rats and mice exposed to MIBK (6 h/day, 5 days/week for 14 weeks) at concentrations between 205–4,100 mg/m3 (50–1,000 ppm) exhibited increased liver weights and liver/body



weight ratios at the highest exposure concentration. No gross or microscopic hepatic lesions related to MIBK exposure were noted. Clinical chemistry values indicative of liver injury were within the normal range.

Disposition and metabolism MIBK is readily absorbed via inhalation (Hjelm et al., 1990) and by analogy to other ketones (Parmeggiani, 1983) is expected to be absorbed through the skin. Following uptake, MIBK is widely distributed throughout the body. RBCs have an important role in the uptake and transport of volatile lipophilic organic solvents such as MIBK. It is readily metabolized to water-soluble excretory products – the urine is the major route of excretion for metabolites. Metabolic biotransformation involves oxidative hydroxylation followed by reduction to the secondary alcohol (DiVincenzo et al., 1976). The alcohol intermediate may undergo glucuronide conjugation or may enter intermediary metabolism with eventual elimination as CO2.

Mutagenicity, carcinogenicity, and developmental/ reproductive effects MIBK did not induce gene mutations when assayed in various in vitro bacterial test systems with or without metabolic activation. Negative findings were also obtained for gene mutation in cultured mammalian cells. The results of in vitro assays for unscheduled DNA synthesis in primary rat hepatocytes and for chromosome damage in cultured rat hepatic cells were negative. MIBK was negative in the micronucleus test. The collective genotoxicity data indicate that MIBK is not genotoxic. There is no indication in the literature that a carcinogenicity assessment has been conducted on MIBK. Mankes and Mankes (chapter 9) have addressed the developmental and reproductive toxicity of MIBK.

6.6.3 Isopropyl alcohol Acute and repeated-dose toxicity Aliphatic alcohols have broad application as solvents, and of this series isopropanol is an important alcohol used in industry, in the home, and in medicine as well as in RCA formulations. It is best known as the main ingredient in rubbing alcohol. Exposure to isopropyl alcohol may occur via the inhalation, oral, and dermal routes. Isopropyl alcohol is more toxic than ethanol but less toxic than methanol – the signs and symptoms of overexposure are similar to that of ethanol poisoning. Isopropanol is a potent CNS depressant – animal studies suggest that isopropanol is about three times as potent a CNS depressant than is ethanol. Its metabolite, acetone is also a CNS depressant. Effects on over-exposure include narcosis, ataxia, muscle incoordination, confusion, unconsciousness, and coma – less common manifestations are renal effects and hypothermia. Cardiovascular irregularities are seen with very high doses of isopropanol. Isopropanol is an irritant and on exposure to the vapor can result in ocular injury (i.e. corneal effects). A review of acute isopropanol intoxication (Lacouture et al., 1983), provides an overview of acute isopropanol poisoning. No long-term health effects have been reported in humans.

Disposition and metabolism Isopropanol is well absorbed via the lungs and rapidly distributed in the body. Dermal exposure to liquid or vapor may occur; however, there is little absorption through the


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intact skin (Martinez et al., 1986). Isopropanol undergoes hepatic metabolism via alcohol dehydrogenase to acetone, which is primarily excreted by the kidneys. The acetone intermediate may undergo further metabolic conversion to acetate, formate, and finally CO2. The rapid metabolism of isopropanol precludes accumulation.

Mutagenicity, carcinogenicity, and developmental/ reproductive effects Isopropanol is not carcinogenic and not mutagenic as assayed in various genotoxicity tests. Isopropanol may pose a developmental/reproductive risks (refer Chapter 9).

6.6.4 Glycols and derivatives Glycols and their derivatives have a variety of applications to include pharmaceuticals, food additives, cosmetics, lubricants, and resins. Propylene glycol and polyethylene glycol (i.e. PEG 300) are used in RCA formulations, particularly in formulations containing CR. Chemically, glycols comprise a class of compounds characterized by two hydroxyl groups on separate carbons of an organic structure. The most common sub-classification of glycols is the 1,2-diols of which propylene glycol is one of the most important members. Polyethylene glycols (PEGs) are polyethers of repeating ethylene oxide units that are highly water soluble and relatively inert biologically. These compounds, with molecular weights ranging from 200 to 6,000, are named for their approximate molecular weights. As PEG molecular weight increases, solubility in water decreases and viscosity and freezing point increases. A polyethylene glycol of a specified molecular weight is composed primarily of the polymer, but may also contain lower-molecular glycols including the monomer ethylene glycol.

6.6.5 Propylene glycol Acute and repeated-dose toxicity Propylene glycol (1,2-propanediol, 1,2-dihydroxypropane) is a common ingredient in many beauty creams, cleansers, makeup, children’s personal care products, various medicines, processed foods as well as having industrial uses. Also, propylene glycol is one of the most commonly used humectants. The US Food and Drug Administration has classified propylene glycol as “generally recognized as safe” (GRAS), which implies that it is acceptable for use in cosmetics, as a direct food additive, in flavorings, and drugs. Propylene glycol has a low order of toxicity (oral, rat LD50 20 g/kg). Ingestion of large amounts may cause gastrointestinal upset – no known health effects via inhalation. Propylene glycol may be associated with adverse health effects involving the liver and kidney and has been found to cause contact dermatitis. For an in-depth review of the health effects of propylene glycol, the reader is referred to the US EPA “Health and Environmental Effects Document for Propylene Glycol (EPA, 1987b).

Disposition and metabolism The metabolism of propylene glycol is similar to that of ethylene glycol.

Mutagenicity, carcinogenicity, and developmental/ reproductive effects Propylene glycol has been studied for mutagenic effects – it is not considered a genotoxic threat. Propylene glycol has been tested for reproductive toxicity in CD-1 mice. Findings



indicated no effect on fertility and reproduction in either generation on administration of propylene glycol (NTP, 1985). Refer Chapter 9 for further discussion related to the developmental/reproductive effects of this compound.

6.6.6 Polyethylene glycols (PEGs) Acute and repeated-dose toxicity A number of studies to ascertain the toxicity of PEGs via various routes of administration to include topical application have been conducted. In general, PEGs are compounds of relatively low order of toxicity. The higher molecular weight ( 1500) PEGs are less toxic than the low molecular weight PEGs. Moreover, the low molecular weight glycols (monomer, dimer, and trimer) are known to be quite toxic (Patty, 1962; Beasley and Buck, 1980). The acute toxicity of various polyethylene glycols are summarized in Table 6.6. A few studies have been conducted related to the potential effects of PEGs on the pulmonary system (Clair and Barletta, 1978; Crook et al., 1981a). Clair and Barletta (1978) exposed guinea pigs to aerosols of PEG 400 and observed alterations in the pulmonary function. Crook and coworkers exposed mice and rats to PEG 200 and reported no biologically significant alterations in lung physiology. Pertaining to irritant potential, PEGs are irritating to the eyes and skin – the lower molecular weight PEGs appear to be more irritating (Smyth et al., 1945). Repeated-dose toxicity studies (i.e. 90-day, 13-week, and lifetime exposure) have been conducted on polyethylene glycols via the oral (Smyth et al., 1945, 1947, 1955; Prentice and Majeed, 1978) and dermal (Smyth et al., 1942, 1945; Luduena et al., 1947; Tusing et al., 1954; Herold et al., 1982) routes and also by inhalation (Crook et al., 1981b). Results of the long-term administration of PEGs via gastric lavage, in diet, or in drinking water indicate that PEGs did not produce significant changes in clinical, biochemical, or histological parameters. Dermal studies conducted by Smyth et al. (1942, 1945) indicated no toxicity as a result of the repeated application of PEGs. However, results from the studies by Luduena et al. (1947) and Tusing et al. (1954) suggest PEG-induced toxicity (impaired liver and kidney function) as ascertained by clinical chemistry parameters. The more recent work by Herold et al. indicate PEG-induced systemic toxicity (i.e. acidosis, hypercalcemia, and renal damage) following repeated topical exposure to PEGs. The renal injury appears

TABLE 6.6 The acute oral toxicity of PEGs in rats Glycol

LD50 (mg/kg)

PEG-200 PEG-300 PEG-400 PEG-600 PEG-1000 PEG-1200 PEG-1500 PEG-2000 PEG-4000 PEG-6000 PEG-10000

28,000 27,500 30,200 30,000 32,000 32,000 44,200 45,000 50,000 50,000 50,000


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to have resulted from the absorption of PEGs and the bioconversion to nephrotoxic compounds (i.e. aldehydes and acids). Herold et al. (1982) have suggested that the differences in the systemic toxicity among PEGs or how well a particular PEG is tolerated is related to the metabolic conversion products formed. In a chronic inhalation study (Crook et al., 1981b) rats and mice were exposed to PEG 200 aerosol (6 h/day, 5 days/week, for 13 weeks). Findings indicated no biologically significant alterations in blood chemistry, hematology, or pulmonary function. No pathological alterations were attributed to the PEG 200 exposure. Generally, the currently held viewpoint regarding the chronic toxicity of PEGs is that these compounds are of a low order of toxicity.

Disposition and metabolism Following topical application, PEGs enter the systemic circulation and undergo metabolic conversion. It is believed that PEGs are most likely metabolized to acid alcohols (i.e. hydroxyglycolic acids) and diacids (i.e. diglycolic acids) as is the case with the metabolic transformation of ethylene glycol (Herold et al., 1982). The detection of PEG-derived metabolites in serum and urine provides evidence that PEGS, like ethylene glycol, are biotransformed in vivo to organic acids. The generation of these acid moieties accounts for the production of metabolic acidosis. Moreover, the mono- and diacids along with the metabolically generated reactive aldehydes are compounds which are highly toxic to renal epithelial cells. The formation of such metabolites may afford an explanation of PEG-induced renal failure.

Carcinogenicity, mutagenicity, and developmental/ reproductive effects PEGs do not appear to pose a significant mutagenic or carcinogenic hazard. Additionally, these materials appear not to pose a significant developmental/reproductive health hazard.

6.6.7 1,1,1-Trichloroethane Acute and repeated-dose toxicity Trichloroethane (methylchloroform), the production having ended in 1996 in the United States, was once an extensively utilized solvent popular with industry. It was used in a variety of consumer products and occasionally utilized as an aerosol propellant. As an aerosol solvent, trichloroethane can solubilize many of the active ingredients in aerosol formulations and can be used in conjunction with hydrocarbon or CO2 propellants. Inhalation is the principal route of exposure to trichloroethane and may also be absorbed through the skin. The health effects of trichloroethane are well characterized (refer to ATSDR, 1995) – the primary effects of acute trichloroethane exposure involve the CNS. The CNS is the most sensitive target organ following inhalation exposure. CNS signs and symptoms of trichloroethane exposure include ataxia, diminished psychomotor performance, narcosis/anesthesia, and altered EEG (Torkelson et al., 1958; Krantz et al., 1959; Stewart et al., 1961; Gamberale and Hultengren, 1973; Mackay et al., 1987). Cardiovascular effects (arrhythmias and hypotension) have been observed on exposure to high concentrations of trichloroethane (Krantz et al., 1959; Dornette and Jones, 1960; Travers, 1974; Guberan et al., 1976; MacDougall et al., 1987). Mortality in humans following acute exposure to high concentrations of trichloroethane is attributed to either depression of the CNS, which results in respiratory arrest (Hall and Hine, 1966; Stahl et al., 1969; Jones and Winter, 1983) or severe cardiac arrhythmias (Travers, 1974;



Guberan et al., 1976). Acute exposure to low concentrations (i.e. 1,000 ppm) of trichloroethane appears not to effect clinical cardiovascular parameters. Moreover, acute exposure to low concentrations have nil to minimal effects on respiratory parameters (Torkelson et al., 1958; Dornette and Jones, 1960). Compared to other chlorinated solvents, trichloroethane is less toxic. As previously stated, high concentrations of 1,1,1- trichloroethane produces CNS depression, incoordination, lung edema, and cardiovascular effects. In animals, exposure can damage the nervous system and liver. Studies of animal mortality following acute inhalation exposure to trichloroethane are numerous. Median lethal concentrations (LC50) have been derived for rats and mice – for rats LC50 estimates range from 10,305 to 38,000 ppm (Adams et al., 1950; Bonnet et al., 1980; Clark and Tinston, 1982). It is lethal at a concentration of 10,000 ppm – the cause of death being respiratory and cardiac failure. Studies have also been conducted to assess its potential to induce morphological alterations in the lungs and related tissues (Adams et al., 1950; Cornish and Adefuin, 1966; Herd et al., 1974; Bonnet et al., 1980). Histological alterations of pulmonary tissue were not evident in these studies. Animal studies of repeated-dose exposure to trichloroethane at doses of up to 1,700 ppm have found no adverse health effects. Exposure to moderate to high levels of trichloroethane for intermediate periods ( 6 months) failed to produce pulmonary lesions in most species tested (Adams et al., 1950; Torkelson et al., 1958; Prendergast et al., 1967; Eben and Kimmerle, 1974; MacEwen and Vernot, 1974). Exposure to high concentrations (1,000–2,000 ppm) results in ocular and pulmonary irritation. As a liquid, trichloroethane causes irritation of the eyes and skin. Chronic inhalation of 1,1,1-trichloroethane did not result in respiratory tract lesions of rats or mice (Quast et al., 1988).

Disposition and metabolism On inhalation, 1,1,1-trichloroethane is rapidly absorbed – high levels are found in tissues such as the brain, liver, fat, and kidneys. It is rapidly eliminated from the body via the lungs and kidneys. About 90% of the absorbed dose is unmetabolized and exhaled and the remainder if biotransformed and excreted in the urine as trichloroethanol and trichloroacetic acid or exhaled as CO2.

Mutagenicity, carcinogenicity, and developmental/ reproductive effects Trichloroethane has been evaluated in a number of studies for its potential to adversely effect reproductive outcome in laboratory animals. In a multigenerational study, mice were administered trichloroethane in drinking water at concentrations equivalent to 100–1,000 mg/kg body weight. No adverse effects on parameters such as fertility, gestation, or survival of offspring were noted.

6.6.8 Defense spray propellants Modern aerosol devices use a compressed gas (e.g. nitrogen or carbon dioxide) or a liquefied gas (e.g. butane, isobutene, propane) as the means to expel the contents of an aerosol canister. Commonly used propellants for defense spray formulations include nitrogen and low molecular weight hydrocarbons (e.g. butane, isobutene, propane). The halogenated alkane (1,1,1,2-tetrafluoroethane, Dymel® 134a/P), which is utilized as a propellant for pharmaceutical applications, is also used as a propellant for self-defense sprays. Moreover, aerosols are not limited to a single propellant formulation and many aerosol formulations contain a mixture of propellants (e.g. butane/isobutene,


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butane/isobutene/nitrogen). A very brief overview of the health effects of various propellants is provided.

Compressed gases (nitrogen) Nitrogen which makes up 78% of the air by volume is colorless, odorless, and a generally inert element. Large amounts of nitrogen are used by the ammonia industry, the electronics industry, the pharmaceutical industry, and food industry as well as in metal processing and refrigeration. Pertaining to toxicity, there are no specific toxicology data for nitrogen. Nitrogen is a simple asphyxiant, which acts to displace oxygen in the environment.

Propane Propane, a simple petroleum gas having relatively low toxicity in humans and animals, is widely used as an aerosol propellant. Propane gas is an anesthetic (Henderson and Haggard, 1943) and is nonirritating to the eyes and skin. The toxic effects of propane as studied in rats are minimal – the LC50 is greater than 800,000 ppm. In monkeys, a depressed breathing rate was the only effect observed following exposures to propane at concentrations between 100,000–200,000 ppm (Aviado, 1975). The principal toxic effect associated with exposure to high concentrations of propane involves the cardiovascular system: in dogs propane induces hemodynamic changes and perturbations in cardiac performance and weak cardiac sensitization at exposures of 150,000 ppm; studies in primates indicated mild cardiac effects on exposure to 100,000 ppm propane (Clayton and Clayton, 1982). Human subjects were exposed to propane at concentrations between 250 and 1,000 ppm and monitored for abnormal physiological responses to include cardiopulmonary parameters – no adverse effects were noted at these exposure levels (Stewart et al., 1978). Propane gas, at concentrations up to 50% by volume, is devoid of mutagenic activity as determined in the Ames assay (Kirwin and Thomas, 1980).

Butane and isobutane Butane is a colorless gas, with a faint disagreeable odor that is slightly toxic via inhalation (rat inhalation 4 hour LC50: 277,000 ppm). In sufficient concentrations, butane gas exhibits anesthetic properties. Butane gas has been reported to be a cardiac sensitizer in guinea pigs and dogs at a concentration of 5,000 ppm – the effects were reversible on cessation of exposure (Reinhart et al., 1971). Butane gas is nonirritant to the eyes and the skin. Butane was found to be nonmutagenic – at several concentrations – in the Ames assay (Kirwin and Thomas, 1980). Isobutane (2-methyl propane), a colorless, flammable gas is an asphyxiant. Isobutane is relatively nontoxic by inhalation. Short-term inhalation exposure to isobutane may cause headaches, dizziness, drowsiness, incoordination, and nausea. At very high concentrations, isobutane can displace oxygen and cause suffocation and loss of consciousness. A simple hydrocarbon, isobutene at high concentrations, can cause irritation of the eyes, mucous membranes, and the respiratory system. No occupational exposure limits have been established for this chemical.

1,1,1,2-tetrafluoroethane Hydrofluorocarbons can be used alone or mixed with other common aerosol propellants in a wide range of personal care and industrial products where the product is dispensed as a spray. Hydrofluorocarbons possess physical properties, which in certain applications make them superior to the hydrocarbon propellants. The hydrofluorocarbon 1,1,1,2tetrafluoroethane (halocarbon 134a, Dymel® 134a) is an aerosol propellant, which is also



manufactured as a pharmaceutical grade product (Dymel® 134a/P) for pharmaceutical applications. Pharmaceutical grade halocarbon 134a is used in current defense spray formulations. Toxicological evaluations have demonstrated that hydrofluorocarbons have a low order of toxicity. Hydrofluorocarbons such as halocarbon 134a may irritate the eyes and skin. The principal physiological action of hydrofluoro-carbons is an anesthetic effect at high exposure levels. High concentrations of 1,1,1,2-tetrafluoroethane can cause headache, dizziness, and drowsiness – very high concentrations may cause suffocation. At very high exposure levels, hydrofluorocarbons can produce cardiac sensitization. These compounds appear to be devoid of genotoxic effects – halocarbon 134a is not listed by IARC (International Agency for Research on Cancer).

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BALLANTYNE, B. and SWANSTON, D.W. (1978) The comparative acute mammalian toxicity of 1-chloroacetophenone (CN) and 2-chlorobenzylidene malononitrile (CS), Archives of Toxicology, 40: 75–95. BALLANTYNE, B., GAZZARD, M.F., SWANSTON, D.W., and WILLIAMS, P. (1974) The ophthalmic toxicology of o-chlorobenzylidene malononitrile (CS), Archives of Toxicology, 32: 149–168. BALLANTYNE, B., GAZZARD, M.F., SWANSTON, D.W., and WILLIAMS, P. (1975) The comparative ophthalmic toxicology of 1-chloroacetophenone (CN) and dibenz[b,f ]1:4-oxazepine (CR), Archives of Toxicology, 34: 183–201. BALLANTYNE, B., GALL, B., and ROBSON, D.C. (1976a) Effects on man of drenching with dilute solutions of o-chlorobenzylidene malononitrile (CS) and dibenz[b,f]1:4-oxazepine (CR) exposure, Medicine, Science and the Law, 16: 159–170. BALLANTYNE, B., GALL, D., and SWANSTON, D.W. (1976b) The ophthalmic toxicology of dichloromethane, Toxicology, 6: 173–187. BEASLEY, V.R. and BUCK, W.B. (1980) Acute ethylene glycol toxicosis: a review. Veterinary and Human Toxicology, 9: 901–905. BESWICK, F.W., HOLLAND, P., and KEMP, K.H. (1972) Acute effects of exposure to orthochlorobenzylidene malononitrile (CS) and the development of tolerance, British Journal of Industrial Medicine, 29: 298–306. BISCOE, T.J. and SHEPHARD, R.J. (1962) Some responses to the intravascular injection of o-chlorobenzal malononitrile in cats and dogs, Archives of International Pharmacodynamics and Therapeutics, 138: 389–399. BISKUP, R.K., SWENTZEL, K.C., LOCHNER, M.A., and FAIRCHILD, D.G. (1975) Toxicity of 1% CR in propylene glyocol/water (80/20), Edgewood Arsenal Technical Report, EB-TR-75009, May 1975. BOGAARDS, J.J.P., VAN OMMEN, B., and VAN BLADEREN, P.J. (1993) Interindividual differences in the in vitro conjugation of methylene chloride with glutathione by cytosolic glutathione-S-transferase in 22 human liver samples, Biochemical Pharmacology, 45: 2166–2169. BONNET, P., FRANCIN, J.M., and GRADISKI, D. (1980) Determination of the median lethal concentration of principal chlorinated aliphatic hydrocarbons in the rat, Archives des Maladies Professionnelles de Medecine du Travail et de Securite Sociale, 41: 317–321. BORNSCHEIN, R.L., HASTINGS, L., and MASON, J.M. (1980) Behavioral toxicity in the offspring of rats following maternal exposure to dichloromethane, Toxicology and Applied Pharmacology, 52: 29–37. BOWERS, M.B., OWENS, E.J., and PUNTE, C.L. (1960) Interim report of CS exposures in plant workers, CWL Technical Memorandum, 24–50 (June 1960), US Army Chemical Warfare Laboratories, Army Chemical Center, MD. BRAEGEAT, P. (1968) Ocular injuries by lacrimogenic agents, Bulletin of the Society of Ophthalmology (France), 68: 531–534. BRIMBLECOMBE, R.W., GREEN, D.M., and MUIR, A.W. (1972) Pharmacology of o-chlorobenzylidene malononitrile (CS), British Journal of Pharmacology, 44: 561–576. BRIVING, C., HAMBERGER, A., KJELLSTRAND, P. et al. (1986) Chronic effects of dichloromethane on amino acids, glutathione and phosphoethanolamine in gerbil brain, Scandinavian Journal of Work and Environmental Health, 12: 216–220. BROOKS, S.M., WEISS, M.A., and BERNSTEIN, I.L. (1985a) Reactive airways dysfunction syndrome, case reports of persistent airways hyperactivity following high-level irritant exposures, Journal of Occupational Medicine, 27: 473–476. BROOKS, S.M., WEISS, M.A., and BERNSTEIN, I.L. (1985b) Reactive airways dysfunction syndrome (RADS), Chest, 88: 376–384. BROWN-GRANT, K., HARRIS, G.W., and REICHLIN, S. (1954) The effect of emotional and physical stress on thyroid activity in the rabbit, Journal of Physiology, 126: 29–40. BUREK, J.D., NITSCHKE, K.D., BELL, T.J., WACKERLE, D.C., CHILDS, R.C., BEYER, R.C., DITTENBER, D.A., RAMPY, L.W., and MCKENNA, M.J. (1984) Methylene chloride: a two-year inhalation toxicity and oncogenicity study in rats and hamsters, Fundamental and Applied Toxicology, 4: 30–47.



CASANOVA, M., DEYO, D.F., and HECK, H.A. (1992) Dichloromethane (methylene chloride): metabolism to formaldehyde and formation of DNA–protein crosslinks in B6C3F1 mice and syrian golden hamsters, Toxicology and Applied Pharmacology, 114: 162–165. CASANOVA, M., BELL, D.A., and HECK, H.A. (1997) Dichloromethane metabolism to formaldehyde and reaction of formaldehyde with nucleic acids in hepatocytes of rodents and humans with and without glutathione S-transferase T1 and M1 genes, Fundamental and Applied Toxicology, 31: 103–116. CHAN-YEUNG, M., and LAM, S. (1986) Occupational asthma, American Review of Respiratory Diseases, 133: 686 –703. CHOWDHURY, A.R., DESHMUKH, M.B., NASHIKKAR, A.B., RAGHUVEERAN, C.D., and CHATTERJEE, A.K. (1978a) Cellular changes of adrenal under the acute stress of o-chloro-benzylidene malononitrile (CS), Experentia, 34: 494–495. CHOWDHURY, A.R., DESHMUKH, M.B., RAGHUVEERAN, C.D., NASHIKKAR, A.B., and CHATTERJEE, A.K. (1978b) Histological changes in thyroid of rat under the acute exposure of CS, Experentia, 34: 6. CHUNG, C.W. and GILES, A.L. (1972) Sensitization of guinea pigs to alpha-chloroacetophenone (CN) and ortho-chlorobenzylidene malononitrile (CS), tear gas chemicals, Journal of Immunology, 109: 284–293. CLAIR, A.G. and BARLETTA, A.L. (1978) Modified technique using perfused isolated guinea pig lung to determine effect of an aerosol constituent on pulmonary dynamics, Journal of Pharmaceutical Sciences, 67: 1002–1004. CLARK, D.G. and TINSTON, D.J. (1982) Acute inhalation toxicity of some halogenated and nonhalogenated hydrocarbons, Human Toxicology, 1: 239–247. CLAYTON, G.D. and CLAYTON, F.E. (eds) (1982) Patty’s Industrial Hygiene and Toxicology, 3rd edition, vol. 2A, 2B, 2C: Toxicology, New York: John Wiley Sons, p. 3181. COLGRAVE, H.F. and CREASEY, J.M. (1975) Ultrastructure of rat lungs following exposure to o-chlorobenzylidene malononitrile (CS), Medicine, Science, and the Law, 15: 187–197. COLGRAVE, H.F., BROWN, R.F.R., and COX, R.A. (1979) Ultrastructure of rat lungs following exposure to aerosols of dibenzoxazepine (CR), British Journal of Experimental Pathology, 60: 130–141. CORNISH, H.H. and ADEFUIN, J. (1966) Ethanol potentiation of halogenated aliphatic solvent toxicity, American Industrial Hygiene Association Journal, 34: 487–492. COTTRELL, T.S., LEVINE, O.R., SENIOR, R.M., WIENER, J., SPIRO, D., and FISHMAN, A.P. (1967) Electron microscopic alterations at the alveolar level in pulmonary edema, Circulation Research, 21: 783–797. CRAFT, B.F. (1983) Solvents and related compounds. In: W.N. ROM (ed.), Environmental and Occupational Medicine, Boston: Little Brown, Chapter 44. CROOK, J.W., COOPER, A.E., HOTT, P., MANTHEI, J.H., WEIMER, J.T., NELSON, R., FARRAND, R.L., and HEITKAMP, D.H. (1981a) The acute toxicity of polyethylene glycol 200 in laboratory animals, Army Chemical Systems Laboratory, ARCSL-TR-81058. Aberdeen Proving Ground, MD. CROOK, J.W., THOMSON, S.A., HOTT, P.D., FARRAND, R.L., COOPER, A.E., LILLY, C., CUMMINGS, E.G., and HEITKAMP, D.H. (1981b) The subchronic inhalation toxicity of polyethylene glycol 200 in the rat and mouse, Army Chemical Systems Laboratory, ARCSL-TR-81051, Aberdeen Proving Ground, MD. CUCINELL, S.A., SWENTZEL, K.C., BISKUP, R., SNODGRASS, H., LOVRE, S., STARKE, W., FEINSILVER, L., and VOCCI, F. (1971) Biochemical interactions and metabolic fate of riot control agents, Federation Proceedings, 30: 86–91. DEBARRE, S., KARINTHI, L., DELAMANCHE, S., FUCHE, C., DESFORGES, P., and CALVET, J.-H. (1999) Comparative acute toxicity of o-chlorobenzylidene malononitrile (CS) and oleoresin capsicum (OC) in awake rats, Human and Experimental Toxicology, 18: 724–730. DIVINCENZO, G.D., KAPLAN, C.J., and DEDINAS, J. (1976) Characterization of the metabolites of methyl n-butyl ketone, methyl isobutyl ketone, and methyl ethyl ketone in guinea pig serum and their clearance, Toxicology and Applied Pharmacology, 36: 511–522. EBEN, A. and KIMMERLE, G. (1974) Metabolism, excretion and toxicology of methylchloroform in acute and subacute exposed rats, Archives of Toxicology, 31: 233–242.


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ROSE, S. and SMITH, R. (1969) CS – a case for concern, New Scientist, 43: 468–469. ROSENGREN, L.E., KJELLSTRAND, P., AURELL, A., et al. (1986) Irreversible effects of dichloromethane on the brain after long-term exposure: a quantitative study of DNA and the glial cell marker proteins S-100 and GFA, British Journal of Industrial Medicine, 43: 291–299. ROTH, V.S. and FRANZBLAU, A. (1996) RADS after exposure to a riot-control agent: a case report, Journal of Emergency Medicine, 38: 863–865. ROTHBERG, S. (1970) Skin sensitization potential of the riot control agents BBC, DM, CN and CS in guinea pigs, Military Medicine, 135: 552–556. SANFORD, J.P. (1976) Medical aspects of riot control (harassing) agents, Annual Review of Medicine, 27: 412–429. SAVOLAINEN, H., PFAFFLI, P., TENGEN, M. et al. (1977) Biochemical and behavioral effects of inhalation exposure to tetrachloroethylene and dichloromethane, Journal of Neuropathology and Experimental Neurology, 36: 941–949. SAVOLAINEN, H., KURPPA, K., PFAFFLI, P. et al. (1981) Dose-related effects of dichloromethane on rat brain in short-term inhalation exposure, Chemical and Biological Interactions, 34: 315–322. SCHWETZ, B.A., LEONG, G.J., and GEHRING, P.J. (1975) The effect of maternally inhaled trichloroethylene, perchloroethane, methyl chloroform, and methylene chloride on embryonal and fetal development in mice and rats, Toxicology and Applied Pharmacology, 32: 84–96. SEROTA, D.G., THAKUR, A.K., ULLAND, B.M., KIRSCHAUN, J.C., BROWN, N.M., COOTS, R.H., and MORGAREIDGE, K. (1986a) A two-year drinking-water study of dichloromethane in rodents I. Rats, Food and Chemical Toxicology, 24: 951–958. SEROTA, D.G., THAKUR, A.K., ULLAND, B.M., KIRSCHAUN, J.C., BROWN, N.M., COOTS, R.H., and MORGAREIDGE, K. (1986b) A two-year drinking-water study of dichloromethane in rodents II. Mice, Food and Chemical Toxicology, 24: 959–963. SHERRATT, P.J., PULFORD, D.J., HARRISON, D.J., et al. (1997) Evidence that human class theta glutathione S-transferase T1-1 can catalyse the activation of dichloromethane, a liver and lung carcinogen in the mouse, Biochemical Journal, 326: 837–846. SHMUNES, E. and TAYLOR, J.S. (1973) Industrial contact dermatitis. Effect of riot control agent CS tear gas, Archives of Dermatology, 107: 212–216. SMYTH, H.F. JR., CARPENTER, C.P., SHAFFER, C.B., SEATON, J., and FISCHER, L. (1942) Some pharmacological properties of polyethylene glycols of high molecular weight (“carbowax compounds”), Journal of Industrial Hygiene and Toxicology, 24: 281–284. SMYTH, H.F., JR., CARPENTER, C.P., and SHAFFER C.B. (1945) The subacute toxicity and irritation of polyethylene glycols and approximate weights of 200, 300, and 400, Journal of the American Pharmaceutical Association, 34: 172–176. SMYTH, H.F., JR., CARPENTER, C.P., and SHAFFER, C.B. (1947) The toxicity of high molecular weight polyethylene glycols: chronic oral and parenteral administration, Journal of the American Pharmaceutical Association, 36: 157–160. Smyth, H.F., CARPENTER, C.P., and WEIL, C.S. (1951) Range finding toxicity data: list IV. Archives of Industrial Hygiene and Occupational Medicine, 4: 119–122. SMYTH, H.F., JR.,CARPENTER, C.P., and WEIL, C.S. (1955) The chronic oral toxicology of the polyethylene glycols, Journal of the American Pharmaceutical Association, 64: 27–30. SPECHT, H., MILLER, J.W., VALAER, P.J., and SAYERS, R.R. (1940) Acute response of guinea pigs to the inhalation of ketone vapors, US Public Health Service, NIH Bulletin 176: 1–66 (Cited in Krasavage et al., 1982). STAHL, C.J., FATTEH, A.V., and DOMINGUEZ, A.M. (1969) Trichloroethane poisoning: observations on the pathology and toxicology in six fatal cases, Journal of Forensic Sciences, 14: 393–397. STEIN, A.A. and KIRWAN, W.E. (1964) Chloroacetophenone (tear gas) poisonings: a clinico-pathological report, Journal of Forensic Sciences, 9: 374–382. STEWART, R.D., GAY, H.H., ERLEY, D.S. et al. (1961) Human exposure to 1,1,1-trichloroethane vapor: relationship of expired air and blood concentrations to exposure and toxicity, American Industrial Hygiene Association Journal, 22: 252–262.



STEWART, R.D., FISCHER, T.N., HOSKO, M.J., PETERSON, J.E., BARETTA, E.D., and DODD, H.C. (1972) Experimental human exposure to methylene chloride, Archives of Environmental Health, 25: 342–348. STEWART, R.D., NEWTON, P.E., BARETTA, E.D., HERRMANN, A.A., FORSTER, H.V., and SOTO, R.J. (1978) Physiological response to aerosol propellants, Environmental Health Perspectives, 26: 275–285. TAHTI, H., AASMOE, L., and SYVERSEN, T. (1999) Organic Solvents. In: B. BALLANTYNE, T. MARRS, T. SYVERSEN (eds), General and Applied Toxicology, 2nd edition, pp. 2029–2042. THILAGAR, A.K., BACK, A.M., KIRBY, P.E., KUMAROO, P.V., PANT, K.J., CLARKE, J.J., KNIGHT, R., and HAWORTH, S.R. (1984) Evaluation of dichloromethane in short term in vitro genetic toxicity assays, Environmental Mutagenesis, 6: 418–419. TORKELSON, T.R., OYEN, F., MCCOLLISTER, D.D., and ROWE, V.K. (1958) Toxicity of 1,1,1-trichloroethane as determined on laboratory animals and human subjects, American Industrial Hygiene Association Journal, 19: 353–362. TRAVERS, H. (1974) Death from 1,1,1-trichloroethane abuse: case report, Military Medicine, 139: 889–890. TRUFFERT, L., GIRARD-WALLON, C., and EMMERICH, E. (1977) Early experimental demonstration of the hepatotoxicity of some chlorinated solvents by the study of the synthesis of hepatic DNA, Archives des Maladies Professionnelles de Medecine du Travail et de Securite Sociale, 38: 261–263. TURNER, C.D. (1964) in General Endocrinology, 3rd edition, WB Saunders Company, Philadelphia, p. 221. TUSING, T.W., ELSEA, J.E., and SAUVEUR, A.B. (1954) The chronic dermal toxicity of a series of polyethylene glycols, Journal of the American Pharmaceutical Association, 43: 489–490. US Environmental Protection Agency (EPA) (1984) Health effects assessment for methylene chloride, Cincinnati, OH, US Environmental Protection Agency, Environmental Criteria and Assessment Office, EPA/540/1-86/028, NTIS No. Pb86-134392. US EPA (1985a) Addendum to the health assessment document for dichloromethane (methylene chloride). Updated carcinogen assessment of dichloromethane (methylene chloride). Final report. Washington, DC; US Environmental Protection Agency, Office of Research and Development. EPA 600/8-82-0044FF. US EPA (1985b) Analysis of the applicability of TSCA Section 4(f) to methylene chloride. Prepared by J. Hopkins. US EPA (1987a) Dichloromethane health advisory, Washington, DC: US Environmental Protection Agency, Office of Drinking Water, December. US Environmental Protection Agency (EPA) (1987b) Health and Environmental Effects Document of Propylene Glycol, Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH. US Environmental Protection Agency (EPA) (1990) Technical Support Document on Health Risk Assessment of Chemical Mixtures, EPA Environmental Assessment and Criteria Office, Cincinnati, OH, EPA/600/8-90/064. VEDDER, E.B. (1925) Medical Aspects of Chemical Warfare, Baltimore: Williams and Wilkins, p. 171. VON OETTINGEN, W.F. (1964) The Halogenated Hydrocarbons of Industrial and Toxicological Importance, Amsterdam, Elsevier. VOS, J.G. (1977) Immune suppression as related to toxicology, Critical Reviews in Toxicology, 5: 67–101. WAY, J.L. (1984) Cyanide intoxication: protection and its mechanism of antagonism, Annual Review of Pharmacology and Toxicology, 24: 451–481. WEIGAND, D.A. (1969) Cutaneous reaction to riot control agent CS, Military Medicine, 134: 437–440. WESTLEY, J., ADLER, H., WESTLEY, L., and NISHIDA, C. (1983) The sulfur-transferases, Fundamental and Applied Toxicology, 3: 377–382. WIGER, R. (1991) Dichloromethane: summary and evaluation of effects on reproduction. In: L. Freij (ed.), Effects on Reproduction of Dichloromethane, n-Hexane, and 1,1,1-Tri-chloroethane, Solna, Sweden: Nordic Chemicals Control Group, pp. 9–27.


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CHAPTER

Pharmacology/Toxicology of Oleoresin Capsicum, Capsaicin, and Capsaicinoids

7

EUGENE J. OLAJOS1 AND JOAN M. LAKOSKI2 1 US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 2

Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania

7.1 INTRODUCTION Personal defense sprays containing oleoresin capsicum (OC) were first developed in the 1970s as an alternative to o-chlorobenzylidene malononitrile (CS) and chloroacetophenone (CN). A highly effective irritant, OC (“pepper spray”) has received considerable attention within the civilian and governmental sectors as a useful and highly effective nonlethal agent. Pepper spray is commonly utilized by both law enforcement personnel and civilians as a form of legal, nonlethal self-protection and has gained widespread acceptance by law enforcement agencies and the public. Individuals affected by OC sprays include law enforcement personnel, criminals, persons accidentally exposed as well as crime victims. Pepper spray is sprayed to the face in order to subdue an assailant resulting in the quick onset of OC-induced effects on the eyes, mucous membranes, and skin. Although pepper spray has gained widespread acceptance, a number of concerns have surfaced pertaining to its use. These include medical (i.e. safety and toxicity of OC, particularly with regard to long-term use), technical (i.e. product specification and effectiveness), operational (i.e. training and safety procedures), and legal/policy issues (i.e. potential for misuse and abuse, guidelines regulating use). The medical and legal concerns have led to reevaluation of OC-based defense sprays as a safe and effective “use-of-force” option to subdue and control violent and/or combative individuals. Concerns have also prompted the development of defense sprays containing “synthetic capsaicin” (nonivamide), whose proponents claim provide greater safety and effectiveness than conventional OC-sprays. Furthermore, the medical and legal concerns have also led to the widespread inclusion of OC-exposure drills to the basic training of law enforcement officers. OC is a complex mixture that is obtained from pepper plants (i.e. Capsicum annuum, Capsicum frutescenes). The composition of OC is highly variable and dependent on factors such as the conditions of extraction, maturity of the fruit, and the environment in which the plants are grown. OC contains capsaicinoids, including the major pungent component


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capsaicin (8-methyl-N-vanillyl-6-nonenamide, 8-methyl-6-trans-nonenoyl-vanillylamide), the principal constituent among the branched- and straight-chain alkyl vanillylamides. OC also contains other compounds (i.e. phenolic compounds, acids, and esters) – these also possess irritant properties. Depending on the variety of chili pepper, OC contains from 0.01% to 1.0% capsaicinoids on a dry mass basis. As a natural product, OC is generally considered safe; however, this viewpoint is not necessarily accurate. Exposure to pepper spray may place individuals at risk for potentially fatal respiratory compromise. OC has been incorporated into various defense spray formulations and marketed as “pepper spray,” “pepper gas,” and “pepper mace ” for law enforcement use, civil disturbance control purposes, criminal incapacitation, and self-defense. As indicated previously, defense spray products containing nonivamide (“synthetic capsaicin”) are currently available. As a spray, OC rapidly produces lacrimation and involuntary closure of the eyes. Exposure to aerosolized OC also elicits respiratory-related effects such as nasal irritation, bronchoconstriction, severe coughing and sneezing, and shortness of breath. OC additionally causes burning sensation of the skin. Other effects attributed to OC include the ability to produce neuromotor dysfunction (i.e. loss of motor control). As a consequence of its actions on the eyes, pulmonary system, and skin, exposed individuals can in most cases be readily subdued following exposure. Acute effects of capsaicin and capsaicinoids are associated chiefly with the respiratory tract and lungs (e.g. bronchospasm, respiratory arrest, pulmonary edema) but may also encompass hypertensive crisis and hypothermia. It is well known, that suprathreshold levels of capsaicin can result in serious respiratory and cardiovascular effects as well as permanent damage to the sensory nervous system. While a substantial number of deaths have occurred related to OC use, a causal relationship to OC has not been established. However, most of the reported deaths have occurred within an hour after exposure and, therefore, the possibility of a direct action should not be excluded in determining the cause of death. Additional information on the chemistry, pharmacology, toxicology, and physiology of OC, capsaicin, and capsaicinoids can be found in numerous articles and reviews (Porszasz et al., 1955; Molnar, 1965; Molnar and Gyorgy, 1967; Makara, 1971; Maga, 1975; Govindarajan, 1977; FEMA, 1978; Virus and Gebhart, 1979; Miller et al., 1982b; Monsereenusorn et al., 1982; Suzuki and Iwai, 1984; Buck and Burks, 1986; Jancso et al., 1987; Fuller, 1990, 1991; Govindarajan and Sathyanarayana, 1991; O’Neill, 1991; Holzer, 1992; Szolcsanyi, 1993; Cordell and Araujo, 1993; Surh and Lee, 1995; Busker and van Helden, 1998). The pharmacology/toxicology of OC, as studied in animals, is presented initially followed by discussion on the multivaried pharmacological actions of capsaicin/capsaicinoids. The repeated-dose toxicology of OC and capsaicinoids is also addressed. The chapter concludes with an overview of the human toxicology of OC and capsaicin/capsaicinoids. The reproductive/developmental toxicology is highlighted in Chapter 9 and an overview of the mutagenic and carcinogenic nature of OC and capsaicin is presented in Chapter 10.

7.2 SENSORY IRRITATION: OLEORESIN CAPSICUM AND CAPSAICIN/CAPSAICINOIDS The sensory irritant effects of OC and of capsaicin has been addressed in Chapter 5 and need not be reiterated. Sufficed to state that OC and the capsaicinoids can elicit profound physiological effects on the eyes and the pulmonary system as well as having an irritative action on the skin. Ocular effects on the eyes (i.e. copious lacrimation, severe burning pain, and blepharospasm) are sufficient to debilitate the individual, and in humans, exposure to OC can cause loss of the blink reflex. Furthermore, it is important to point out that


PHARMACOLOGY/TOXICOLOGY OF OC, CAPSAICIN, AND CAPSAICINOIDS

unlike the other riot control agents (RCAs), capsaicin applied to the eye leads to neurogenic inflammation (vasodilatation and extravasation) as well as unresponsiveness to chemical and mechanical stimuli. Regarding the respiratory tract, OC and capsaicinoids, in particular capsaicin, are without question extremely potent sensory irritants of the respiratory system. Regarding the dermal irritative properties of OC and capsaicinoids, exposure to OC and capsaicin and its congeners produces an intense burning sensation of the skin accompanied by erythema and an inflammatory reaction.

7.3 PHARMACOLOGY AND TOXICOLOGY OF OLEORESIN CAPSICUM, CAPSAICIN/CAPSAICINOIDS Toxicological studies have been conducted on both capsaicin and OC; however, despite extensive field application, few formal evaluative studies of OC have been conducted. Because OC is a much-utilized food component, OC is widely regarded as safe with a low degree of toxicity (Clede, 1993). Unlike other lacrimatory agents such as CN, CR, and CS, which have definite chemical compositions, OC is a mixture of compounds containing capsaicin and its structural analogs, various acids and esters, alcohols, aldehydes, and ketones; and carotenoid pigments (Suzuki et al., 1980; Teranishni et al., 1980; Games et al., 1984; Govindarajan, 1986; Cordell and Araujo, 1993). Numerous compounds in OC have been identified via gas chromatography–mass spectrometry (GC-MS) by Keller et al. (1981). The capsaicinoid content of the dried fruit has been reported to range from 0.1% to 1% (Govindarajan and Sathyanarayana, 1991). The capsaicinoid content of the oleoresin was as follows: capsaicin (~70%), dihydrocapsaicin (~20%), nordihydrocapsaicin (~7%), homocapsaicin (~1%), and homodihydrocapsaicin (~1%). Recently, Reilly et al. (2001) have performed quantitative analyses of capsaicin and capsaicinoids in OC, in fresh peppers, and in OC spray products. The capsaicin content of OC samples ranged between 33% and 48%. The capsaicinoid analog content for various OC samples were as follows: dihydrocapsaicin (35.8–48.0%), nordihydrocapsaicin (7.7–19.7%), homocapsaicin (1.3–7.0%), and homodihydrocapsaicin (1.9–2.9%). Overall, data on the toxicology of OC is extant particularly regarding effects following exposure to OC via the inhalation route. Recer et al. (2002) cite acute lethality data for OC by Loktionov and Mukovsky (1995). LCt50 estimates for OC are as follows: rat (835,000 mg-min/m3) and mouse (270,000 mg-min/m3). Recent inhalation studies on OC have indicated that the toxicity of OC may be minimal following inhalation exposure. (Mioduszewski, 1997; Debarre et al., 1999). Debarre and coworkers (1999) conducted noseonly inhalation exposures in rats to ascertain the effects of aerosolized OC as well as of various solvents. Pulmonary physiology parameters were evaluated to determine alterations in respiratory function as well as histopathologic evaluation of pulmonary tissues. The salient finding following exposure to OC was decreased minute volume. Histopathologic changes included interstitial edema of the lungs and epithelial lesions of the trachea. Debarre et al. (1999) suggested that additional studies are needed using an animal model of bronchial hyperresponsiveness (i.e. rat (Long et al., 1997)) to better assess the risk of individuals with compromised pulmonary function following exposure to RCAs and irritant chemicals. The pharmacological and toxicological effects of capsaicin are far better characterized than that of OC. Because capsaicin is the principal active ingredient of OC, little consideration has been given to the other capsaicinoids as to their biological effects and mechanism(s) of action. Generally, these analogs have effects similar to capsaicin although with different potencies (Cordell and Araujo, 1993). As early as the 1920s, capsaicin was prepared for evaluating physiological and pharmacological effects in humans. Although interest in the development of capsaicin as a


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RCA waned as research efforts were directed to understanding the biological actions of the newly synthesized agent CS, capsaicin has been extensively investigated by the medical research community for its pharmacological effects and clinical uses. The severity of capsaicin-induced toxic effects in vivo depends on factors such as route of administration, the dose of capsaicin, and the age of the animal. In a multispecies (rats, mice, hamsters, guinea pigs, and rabbits) study, Glinsukon et al. (1980) have derived LD50 values for capsicum extracts and capsaicinoids. Representative values for capsaicin are 0.56 mg/kg, intravenous 7.6 mg/kg, intraperitoneal; 7.8 mg/kg, intramuscular; 9. 0 mg/kg subcutaneous; 190 mg/kg, intragastric; 512 mg/kg, dermal; and l.6 mg/kg, intratracheal. It was noted that the toxicity of capsaicin in the capsicum extract was about four-fold greater than that of pure capsaicin administered intraperitoneally. The most likely cause of death was respiratory paralysis. Findings indicated that guinea pigs were more susceptible than mice or rats, whereas hamsters and rabbits were less vulnerable to the toxic actions of capsaicin. Pharmacological and toxicological studies – to include inhalation exposures – have contributed to a better understanding of capsaicin-induced effects and actions on the living organism. The acute biological effects of capsaicin are due to the release of bioactive compounds (e.g. substance P, neurokinin A, and calcitonin gene-related peptide) from sensory nerves by capsaicin resulting in the following: (1) altered neurophysiology of sensory neurons in the airway mucosa, and (2) neuro-mediated inflammation of the epithelium, airway blood vessels, glands, and smooth muscle. These perturbations lead to bronchoconstriction, mucous secretion, edema of the tracheobronchial mucosa, enhanced vascular permeability, and neutrophil chemotaxis (refer to Chapter 4 for a more in-depth discussion). The multi-varied pharmacological actions of capsaicin and capsaicinoids were characterized in the 1950s (Issekutz et al., 1950a,b; Porszasz et al., 1955, 1957; Toh et al., 1955) and further elucidated in the 1980s (for reviews refer to Fitzgerald, 1983; Buck and Burks, 1986; Maggi and Meli, 1988; Holzer, 1991). Recently, characterization of the “vanilloid” receptor (VR1) (Caterina et al., 1997; Hayes et al., 2000) and the identification of a variety of other vanilloid receptor-like proteins (e.g. VRL-1, VRL-2) (Caterina et al., 1999; Schumacher et al., 2000; Delany et al., 2001) have contributed to a greater understanding of the spectrum of capsaicin/capsaicinoid-induced pharmacological activity. Moreover, vanilloid receptor-like proteins are expressed in nonneural tissues (e.g. epithelial cells of the kidneys and respiratory tract) (Hayes et al., 2000; Delany et al., 2001; Sanchez et al., 2001). Capsaicin has a spectrum of effects on sensory neurons, to include cell death, and as previously stated, suprathreshold amounts of capsaicin can cause irreversible damage to the sensory nervous system (Jancso, 1968; Jancso et al., 1968, 1981, 1985, 1987; Szolcsanyi, 1977, 1980, 1982, 1984a,b, 1987; Nagy et al., 1980; Foster and Ramage, 1981; Lembeck and Donnerer, 1981; Nagy, 1982b; Matsumiya et al., 1983; Konietzny and Hensel, 1983; Bevan et al., 1987; Lynn, 1987; Holzer, 1992). The functions of capsaicin-sensitive sensory neurons, representative therapeutic applications of capsaicin, and pathophysiological implications following treatment/ exposure to suprathreshold doses are highlighted in Table 7.1. It has been generally assumed that capsaicin’s neurotoxic effects are limited to sensory neurons with small diameter unmyelinated afferent processes ( Jancso and Kiraly, 1980, 1981; Nagy, 1982a; Russell and Burchiel, 1984; Jancso et al., 1985; Buck and Burks, 1986; Holzer, 1988, 1991; Maggi and Meli, 1988). However, findings reported by Ritter and coworkers (Ritter and Dinh, 1988, 1990, 1991, 1992, 1993) suggest that capsaicin-induced neurotoxicity is more widespread in the nervous system than previously assumed. Dependent on dosage and other factors, systemic administration of capsaicin produces degeneration of cell bodies, axons, and nerve terminals at specific sites throughout the entire neuroaxis. Capsaicin has been effectively used as a selective probe to study the role of neurogenic inflammation, a phenomena resulting from stimulation of certain types of sensory nerves producing vasodilatation and extravasation. Reference to this condition as



TABLE 7.1 Functions of capsaicin-sensitive sensory neurons, pathological implications of capsaicin exposure, and clinical applications Visceral afferents “Afferent” function Nociception and reflex homeostasis Cardiovascular regulation “Efferent” function Neurogenic plasma extravasation Vascular control Mucous secretion Smooth muscle contraction

Somatic afferents “Afferent” function Nociception and reflex homeostasis Cardiovascular regulation “Efferent” function Neurogenic plasma extravasation Modulation of inflammatory reactions Antidromic vasodilatation

Pathological implications of capsaicin damage Reduced response in detecting noxious stimuli and loss of homeostasis Weakened resistance of tissue (i.e. gastric) to injurious stimuli, altered gastric mucosal defense mechanisms Skin pathophysiology as a result of altered blood flow and vascular permeability Corneal opacities

Representative clinical applications of capsaicin Ablation of skin inflammatory responses (i.e. wealing) Treatment of urogenital dysfunction (i.e. bladder hyperreflexia)

Sources: Pathological implications (Szolcsanyi and Bartho, 1981; Fujita et al., 1984; Evangelista et al., 1987; Maggi et al., 1987a,b; Holzer and Sametz, 1986; Bevan and Yeats, 1991, Holzer, 1993; Campbell et al., 1993): Clinical applications (Toth-Kasa et al., 1983; Fowler et al., 1992; Campbell et al., 1993).

neurogenic inflammation is attributed to Jancso (1960) and has been the object of extensive research ( Jancso et al., 1967, 1968; Jancso, 1968; Jancso-Gabor and Szolcsanyi, 1969; Lembeck and Holzer, 1979; Nagy, 1982a; Jancso, 1984; Foreman and Jordan, 1984; Lynn and Shakhanbeh, 1988; Holzer, 1988, 1991). Capsaicin has also been used to elucidate the role of nociceptors and has gained the status of an invaluable tool in sensory neuron research (Nagy, 1982b; Fitzgerald, 1983; Buck and Burks, 1986). In addition to capsaicin-induced effects on thin sensory neurons, capsaicin exerts action on nonsensory neurons and nonneural excitable cells. These physiological effects of capsaicin include inhibition of cardiac muscle excitability (Zernig et al., 1984; FrancoCereceda and Lundberg, 1988), inhibition of visceral smooth muscle activity (Bartho et al., 1982, 1987), and contraction of vascular smooth muscle (Donnerer and Lembeck, 1982; Edvinsson et al., 1990). In addition, capsaicin has been reported to influence various metabolic processes (Miller et al., 1983). Importantly, the cell-nonselective effects of capsaicin are typically produced by concentrations of capsaicin that are far in excess of those needed to stimulate sensory neurons. The airway mucosa is highly sensitive to capsaicin and exposure to this substance leads to intense irritation, which in severe cases is highly painful to the nasal passages (Stjarne et al., 1991). In the nasal passages, activation of capsaicin-sensitive sensory nerves results in profound vasodilation, secretion, and increased nasal mucosal volume. Capsaicin markedly influences pulmonary function and mechanics, and the pulmonary toxicology of capsaicin has been studied in some detail.


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Capsaicin activates protective reflexes such as avoidance (Gamse, 1982; Russell and Burchiel, 1984; Buck and Burks, 1986) or bronchoconstriction, sneezing, coughing, and apnea and rapid shallow breathing in response to airway irritation (Coleridge and Coleridge, 1984; Lundblad, 1984; Lundberg and Saria, 1987; Forsberg et al., 1988). Apnea followed by rapid shallow breathing is the classical chemoreflex response on stimulation of sensory neurons in the lung. All of the aforementioned reflexes function to restrict access of irritant material to lower airways. Furthermore, activation of sensory neurons of the upper and lower respiratory tract is associated with increased vascular permeability to plasma proteins in the airway mucosa (Lundberg and Saria, 1982a). Other reflexes involve cardiovascular (Crayton et al., 1981; Jancso and Such, 1983; Szolcsanyi et al., 1986), neuroendocrine (Mueller, 1981) and thermoregulatory (Szolcsanyi, 1982; Hayes et al., 1984; de Vries and Blumburg, 1989) control mechanisms. Capsaicin may induce the Kratschmer reflex which, on inhalation of an irritant, causes cardio-respiratory dysfunction which is characterized as consisting of apnea, bradycardia, and a biphasic fall and subsequent rise in aortic blood pressure. The bronchoconstriction and airway mucosal edema manifested in laboratory animals and humans exposed to capsaicin are phenomena associated with the release of the neuropeptide substance P from sensory nerve terminals ( Jancso et al., 1977; Russel and Lai-Fook, 1979; Davis et al., 1982; Lundberg and Saria, 1982b; Fuller et al., 1985; Martling et al., 1987; Hathaway et al., 1993). A more in-depth discussion pertaining to substance P-induced physiological effects is found in Chapter 4. In addition to the depletion of substance P, there is also depletion of other neuropeptides from primary sensory neurons, namely, neurokinin A (NKA), calcitonin gene-related peptide (CGRP), somatostatin (SOM), and kassinin as revealed by immunohistochemistry and radioimmunoassay (Gamse et al., 1981; Priestley et al., 1982; Lundberg et al., 1983a, 1985; Maggio and Hunter, 1984; Hua et al., 1985; Gibbins et al., 1985; Martling, 1987; Forsberg et al., 1988; Martling et al., 1988; Martins et al., 1991). A number of substances have antagonistic activity towards capsaicin. Capsazepine is the prototype competitive antagonist of capsaicin – isovelleral is also an antagonist. Capsazepine (2-[2-(4-chlorophenyl) ethylaminothiocarbonyl]-7,8-dihydroxy-2,3,4, 5-tetrahydro -1H-2-benzapine) is structurally related to capsaicin and potentially antagonizes all sensory neuron selective actions of capsaicin but lacks agonist activity (Bevan et al., 1991; Dray et al., 1991). The dye Ruthenium Red has also been demonstrated to exhibit antagonistic actions to capsaicin-induced effects on sensory neurons. Blockade of capsaicin-induced excitation and desensitization by Ruthenium Red has been demonstrated by a number of investigators (Maggi et al., 1988a,b; Chahl, 1989; Amann and Lembeck, 1989). The pulmonary system effects of capsaicin are also species related. In the guinea pig, intravenous and intra-arterial dosing causes bronchoconstriction (Biggs and Goel, 1985). In the dog and cat, intravenous dosing of capsaicin results in bronchoconstriction that is dependent on a vagal cholinergic reflex. Aerosol exposure of cats to capsaicin also evokes a vagal-mediated cholinergic reflex bronchoconstriction (Adcock and Smith, 1989). Studies designed to elucidate the mechanism by which aerosolized capsaicin causes bronchoconstriction in guinea pigs suggest a vagal/cholinergic and non-cholinergic local axon reflex contributes to this effect (Buchan and Adcock, 1992). Capsaicin is known to induce complex effects on the cardiovascular system, which consist of tachypnea, hypotension (seen in the Bezold-Jarrish reflex), bradycardia, and apnea. The cardiorespiratory effects of capsaicin have been best studied following intravenous dosing. In rats and guinea pigs, capsaicin treatment resulted in a triphasic effect on blood pressure and altered cardiac parameters (Chahl and Lynch, 1987; Porszasz and Szolcsanyi, 1992). Perturbations in thermoregulation can also result following the administration of capsaicin/capsaicinoids (Issekutz et al., 1950 a,b; Jancso et al., 1966; Jancso-Gabor et al.,



1970 a,b; Szolcsanyi and Jancso-Gabor, 1973; Cabanac et al., 1977; Hori and Harada, 1977; Obal et al., 1983; Szolcsanyi, 1983; Hori, 1984); for an authoritative review refer to Szolcsanyi, 1982). Capsaicin has been used for the last 25 years as the tool of choice in elucidation of the physiological processes underlying the control of body pain and temperature. It has been demonstrated that pretreatment/treatment of animals with capsaicin results in severely impaired heat escape behavior and induces an irreversible impairment in thermoregulation (Jancso et al., 1966; Jancso-Gabor et al., 1970a; Hori, 1980; Hori and Tsuzuki, 1978; Szolcsanyi, 1983). In elevated temperature environments, body temperature rose concomitant with an inability to discriminate and seek cooler environments (Szolcsanyi, 1983). Additionally, capsaicin-treated animals, consumed less water and became dehydrated. It was noted in these studies that dermal blood vessels failed to dilate, and the animals did not take appropriate behavior to prevent heat stroke. Szolcsanyi (1983) also observed that the subcutaneous administration of capsaicin reduced body temperature, and that the dosing regimen resulted in a tolerance to thermal regulation. Studies by Frens (1977) demonstrated that subcutaneous injections of capsaicin decreased body temperature in goats. In humans, Konietzny and Hensel (1983) demonstrated that the topical administration of capsaicin and capsaicinoids had lowered the threshold to thermal pain. The collective data regarding capsaicin-induced perturbations of thermoregulation support the notion that capsaicin and capsaicinoids have potentially adverse physiological consequences to individuals exposed to these substances at elevated temperatures. The effects of capsaicin and capsaicinoids on the gastrointestinal tract and nutritional impacts have also been examined (Nopanitaya, 1974; Nopanitaya and Nye, 1974; Sambaiah et al., 1978; Kawada et al., 1986; Jang et al., 1992). The duodenal mucosal response to capsaicinoids and altered fat uptake by damaged duodenal epithelium, as reported by Nopanitaya (1974) and Nopanitaya and Nye (1974), have led to subsequent studies on the alteration of nutrient absorption and metabolism by capsaicinoids. Animal studies by Sambaiah et al. (1978, 1984) and Kawada et al. (1986) indicated that capsaicinoids had no adverse effect on fat intake or absorption. The lipotropic and hypolipidemic effects of capsaicinoids have also been examined in some detail (Sambaiah and Satayanarayana, 1982a,b; Kawada et al., 1986). Sambaiah and Satayanarayana (1982b) postulated that capsaicinoids counteract the accumulation of fat in the liver by the reduction of hepatic lipogenesis and/or increased oxidation of lipids.

7.3.1 Repeated-dose toxicity of OC and capsaicin/capsaicinoids Repeated-dose administration of capsaicin produces systemic desensitization to chemogenic and thermal nociceptive stimulation ( Jancso et al., 1977; Hayes and Tyers, 1980; Hayes et al., 1980, 1981; Miller et al., 1980, 1981; Gamse et al., 1980). Desensitization may be considered as the initial manifestation of the long-term neurotoxic action of capsaicin on sensory neurons. This response may also imply a readily reversible functional refractoriness in the absence of morphological changes. Experimental data suggest that exposure to high doses of capsaicin and its analogs results in long-lasting insensitivity to stimuli such as irritants, pain, and temperature (Govindarajan and Sathyanarayana, 1991). Capsaicin-induced desensitization, which may be manifested for weeks, is associated with reversible structural changes. Long-term effects, involving the pulmonary system, are characterized by desensitization of the airways to chemical irritants and the marked inhibition of vagal bronchoconstriction effects (Lundberg and Saria, 1982b). It is postulated that capsaicin-induced desensitization results from the acute and excessive depletion


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of the neurotransmitter substance P. Physiologically, this depletion is expressed as a lack of normal biological response to stimuli such as heat and cold. High doses of systemic capsaicin produce a permanent or long-lasting desensitization of capsaicin-sensitive afferent nerves in newborn rats (Jancso and Kiraly, 1981; Nagy et al., 1983; Jancso et al., 1987). In adult rats, similar doses elicit a long-lasting but temporaneous block of the nerves (Buck and Burks, 1986; Jancso et al., 1987). In both instances, transmission of pain in response to various noxious stimuli was inhibited or abolished in animals dosed with capsaicin. The effect is postulated to be capsaicin induced and the resulting neurodegeneration of C-fiber receptors ( Jancso et al., 1977). More recent findings suggest that this effect can be dissociated by using lower doses of capsaicin (Dray et al., 1989). The bulk of available toxicological data on the effects of repeated dosing of capsaicin and capsicum was reported by Lee (1963a,b), Nopanitaya (1973), and Monsereenusorn (1983) – also refer Chapter 8 on chronic toxicity. Multiple dosing of capsaicin and capsicum in the rabbit resulted in pathological alterations in several organ systems (Lee 1963a,b). In the study reported by Lee (1963a) capsaicin resulted in hepatic necrosis following multiple-dose administration. Mice fed with a diet containing capsicum extract for 4 weeks did not exhibit signs of toxicity (Jang et al., 1992). Intragastric administration of capsaicin (50 mg/kg/day) or crude extract of capsicum (0.5 mg/kg/day) for 60 days was conducted in rats by Monsereenusorn (1983). Biochemical parameters altered by capsaicin and crude extract included significant reductions in plasma urea nitrogen, glucose, phospholipids, triglyceride, transaminase, and alkaline phosphatase. Significantly lower growth rates were noted in both the capsaicin and OC-treated groups – these findings are in concordance with those reported by Nopanitaya (1973).

7.3.2 Reproductive/developmental toxicity of OC and capsaicin/capsaicinoids The pharmacological and toxicological effects of capsaicin/capsaicinoids on specific body and/or organ systems, in particular the sensory systems, the cardiovascular and respiratory system, and the gastrointestinal system, have been well characterized. However, the literature remains extant concerning studies that have addressed the impact of OC and capsaicin/capsaicinoids on reproductive health (i.e. female and male reproductive function and physiology, fetal development). The available data suggest that OC and capsaicinoids have minimal effects on reproductive/developmental parameters (refer Chapter 9 by Mankes and Mankes).

7.3.3 Mutagenesis and carcinogenesis of OC and capsaicin/capsaicinoids Concern regarding the mutagenic and carcinogenic potential of OC and capsaicinoids stems from the ability of capsacinoid metabolic products to alkylate genetic material. The widespread use of OC and capsaicin as the active ingredient in self-defense sprays, as a food additive, and their medicinal/therapeutic applications requires that this issue deserves serious consideration. Numerous studies have been conducted to determine the mutagenic and carcinogenic potential of OC and capsaicin/capsaicinoids, but findings are discordant. A detailed discussion on the mutagenicity and tumorigenicity of capsaicinoids is presented by Durnford (Chapter 10), which examines findings in the literature and addresses our current understanding of capsaicin/capsaicinoid-induced mutagenesis and carcinogenesis.



7.4 HUMAN PHARMACOLOGY AND TOXICOLOGY OF OC AND CAPSAICIN/CAPSAICINOIDS OC (“pepper gas”), purportedly safe and effective, has seen increased adoption and utilization by law enforcement agencies. Smith and Stopford (1999) have reviewed the effects of exposure to OC sprays and have discussed the occupational health risks associated with its use (also refer Stopford and Sidell (Chapter 11) and Stopford (Chapter 14) ). Onnen (1993) on the subject of OC, as related to law enforcement, cited findings by Weaver and Jett (1989) who reported the lack of adverse effects in humans exposed to OC. Watson et al. (1996) reported the findings of a retrospective study of individuals admitted to emergency departments following OC-spray exposure from law enforcement action as well as cases that were not law enforcement related. The objective was to describe the clinical effects to include adverse effects associated with OC-spray use. The authors concluded that emergency department evaluation and medical intervention was infrequent following exposure to OC spray. The most common findings were transient burning sensation, erythema, and localized irritation – none of the patients had adverse outcomes attributed to OC exposure. A number of studies (Lee et al., 1996; Zollman et al., 2000) have been conducted in human subjects to ascertain the effects of self-defense sprays containing OC as the active ingredient. Lee and coworkers (1996) examined the effects of a commercially available OC spray on visual acuity, corneal integrity, and conjunctival appearance in human volunteers. Exposure to OC spray resulted in an immediate and intense blepharospasm, burning sensation, conjunctival injection, excessive mucous secretion, and respiratory dysfunction; visual acuity measured 15 minutes after exposure appeared unchanged from preexposure values. Corneal injury was not evident following spray exposure; however, several subjects sprayed with devices equipped with burst nozzles exhibited some corneal injury; these injuries resolved completely within 24 hours and had not required medical treatment. A second exposure study was conducted using burst-nozzle type “inert” sprays containing methyl salicylate in place of OC. The intent of this study was to determine whether the corneal lesions observed in the previous tests were due to OC, carrier (isopropanol), propellant (isobutane), or to the “inert” ingredient methyl salicylate (“wintergreen”). Based on the findings from the second set of studies, Lee et al. postulated that a component – other than OC or methyl salicylate – may have caused the corneal lesions. Isopropanol was suspected as the component most likely to have caused the corneal lesions, since isopropanol is quite toxic to corneal epithelial cells (Grant, 1974; Roseman and Hill, 1987). An additional evaluation was performed in a single individual exposed to a mixture of isopropanol and isobutane sprayed from an aerosol canister; ocular examination revealed superficial epithelial loss, which suggest that a component(s) in the spray other than OC is capable of causing ocular injury. In spite of these collective findings, the conclusions drawn may not have been entirely correct since the known irritant properties of methyl salicylate were not evaluated. Methyl salicylate is known to cause eye irritation and under certain conditions the degree of irritation may be rather severe, with permanent damage (Carpenter and Smyth, 1946; Grant, 1986; Sax and Lewis, 1989) It remains unclear why Lee et al. selected methyl salicylate as the ingredient replacing OC in the “inert” spray in light of the known irritating properties of methyl salicylate. In another human subject study on the ocular effects of pepper spray, Zollman and colleagues (Zollman et al., 2000) conducted studies using police cadet volunteers. Cognizant of the potential corneal epithelial toxic effects associated with alcohol-based OC sprays, a water-based OC spray was utilized. Subjects were sprayed (face only) with either of two commercially available defense sprays containing 0.5 or 1.0 million Scoville Heat Units (SHU). Ocular effects were evaluated at 10 minutes, 1 hour, and 1 week postexposure


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times. OC was effective in producing significant ocular pain and blepharospasm; tearing and blurred vision were also noted. Corneal sensation was severely affected at 10 minutes and at 1 hour. Blepharospasm was evident in all subjects at 10 minutes, but was not seen at 1 hour. Conjunctival injection was a significant finding on examination, which decreased in severity by about one hour after cessation of exposure. Punctate epithelial erosions were also noted on exposure to OC spray; however, no corneal abrasions were found. At one week after exposure, corneal sensation returned to baseline and corneal abnormalities were not seen. These findings are in agreement with previously published data (Lee et al., 1996; Watson et al., 1996; Busker et al., 1998). Zollman and colleagues concluded that their findings support the use of OC as a relatively safe and effective means to rapidly disable an individual. They have also advocated that additional research should focus on the potential long-term effects following OC exposure, especially as one takes into account the likelihood for multiple exposures experienced by law enforcement and correctional facility personnel. Recently, a number of reports have appeared pertaining to in-custody deaths and pepper spray use (Granfield et al., 1994; Steffee et al., 1995). Granfield and colleagues (1994) have published their findings of their review of aggregated data related to in-custody deaths where pepper spray was used. Thirty in-custody cases were reviewed to ascertain the role of pepper spray as unrelated, contributory, or causative. They concluded that OC had not contributed to or was not the cause of death in 22 cases where sufficient information permitted a thorough review. Granfield et al. also discussed factors/conditions (e.g. positional asphyxia, cocaine intoxication, excited delirium (cocaine-induced), and neuroleptic malignant syndrome). In-custody deaths following OC (pepper spray) use was also the subject of a paper by Steffee et al. (1995), which described two cases of incustody death, both associated with the use of pepper spray. A detailed autopsy and toxicologic analysis was performed coupled with premortem chain of events, symptomatology, and degree of natural disease processes. Findings in the first case indicated that pepper spray neither caused nor contributed to the death; whereas in the second case, findings suggested a direct contribution of pepper spray to the individual’s death. A recent study (Chan et al., 2001) addressed the physical restraint and positional asphyxia issue associated with the use of OC spray. These investigators examined in human subjects the combined effects of OC spray exposure and positional restraint on pulmonary mechanics and function. In both the OC and control groups, pulmonary function parameters were compromised in the restraint position, but values were within a normal range. The authors concluded that the study findings support the hypothesis that exposure to OC spray does not pose a major risk to subjects, even under conditions of positional restraint. Of critical note, however, is that several caveats were expressed, namely, that in a laboratory setting, one would not be able to replicate some or all the conditions that would be encountered in the field – particularly the psychological and physiological effects of exertion, stress, and trauma. In the field, subjects are often in a state of extreme agitation and excitement as a result of the effects of drugs and/or alcohol or from the effects of an underlying psychiatric disorder. Moreover, it should be noted that the study by Chan and coworkers focused on inhalation exposure with the subjects provided with eye protection to reduce OC exposure to the eyes. In contrast, under field conditions, ocular exposure exacerbates the physiological stress; this important aspect was not assessed in this study. Irrespective of the study design, Chan and colleagues have provided critical and useful information regarding OC spray-induced respiratory and pulmonary changes. Overall, these study findings lend credence to the retrospective field studies that have found minimal evidence of significant respiratory consequences and injury following OC exposure. On the broader issues related to incustody deaths, the reader is referred to an excellent paper by Lifschultz and Donaghue (1991). Of additional considerable interest, concerning the potential life-threating and ill



effects of OC, is a report by Billmire et al. (1996) which described the adverse health consequences of OC spray (pepper gas) in an infant. In that incident, a 4-week old healthy infant was exposed to 5% pepper gas when a self-defense device was accidentally discharged; the subject experienced respiratory failure and hypoxemia. Treatment regimen following this exposure included extracorporeal membrane oxygenation. The patient was discharged and a subsequent 12-month follow-up was conducted which revealed several episodes of viral respiratory infections. In comparison to the relatively few human studies on OC, a considerable number of studies have been published concerning the human response to inhaled capsaicin (Fuller et al., 1985, 1988; Maxwell et al., 1987; Nichol et al., 1990; Barros et al., 1991; Bascom et al., 1991; Fuller, 1991; Philip et al., 1994). The human pharmacology of capsaicin has been reviewed by Fuller (1990), and Watson et al. (1996) among others have described the clinical effects in individuals exposed to OC. The probable lethal oral dose of capsaicin for humans is considered to be 0.5–5.0 g/kg (Gosselin et al., 1976). The upper respiratory tract effects on exposure to capsaicin have been described (Bascom et al., 1991; Geppetti et al., 1993). Healthy young human adult subjects that were challenged intranasally with capsaicin manifested rhinorrhea, sneezing, nasal burning, and congestion (Bascom et al., 1991), and capsaicin application to the nasal mucosa produced a painful sensation and copious secretion of nasal fluid (Geppetti et al., 1993). The studies by Geppetti et al. (1993) support the hypothesis that the therapeutic effectiveness of capsaicin treatments in painful diseases might not be linked to nerve fiber degeneration due to the neurotoxic effect of capsaicin, but might rely on desensitization of the mechanism activated by capsaicin on the nerve terminal. It is important to note, that the larynx may represent the primary site of stimulation of inhaled capsaicin (Collier and Fuller, 1984). Because respiratory impairment is one of the most obvious effects observed in capsaicin-exposed animals, bronchoconstriction has been the subject of a number of human studies on capsaicin (Lundberg et al., 1983b; Fuller et al., 1985; Fuller, 1991; Hathaway et al., 1993). Fuller and coworkers (1985) demonstrated that when inhaled in humans, capsaicin produced a dose-dependent bronchoconstriction that was the same as in asthmatics and smokers. The majority of subjects manifested coughing and all reported retrosternal discomfort. The studies by Fuller and colleagues (Fuller et al., 1985; Fuller, 1991) confirmed that the bronchoconstrictor reflex following capsaicin stimulation in animals is also present in humans. The capsaicininduced bronchoconstriction and the release of substance P, the putative neurotransmitter/ neurogenic mediator found in sensory neurons, are caused by stimulation of the C-fibers of the nonmyelinated afferent fibers. These studies and those using isolated human airway preparations showed that repeated-dosing causes tachyphylaxis. In humans, the mechanism of bronchoconstriction following inhalation of capsaicin is uncertain, but possible mechanisms can be inferred from animal studies. In summary, our knowledge of the pharmacological profile of OC and capsaicin/ capsaicinoids and the molecular basis for the varied actions of capsaicin/ capsaicinoids has grown considerably in the past several years. An improved understanding of the “vanilloid” receptor and vanilloid receptor-like proteins, the molecular mechanisms by which capsaicinoids cause inflammation and cellular injury, capsaicin-induced biological actions to include cytotoxic effects, and the effects of capsaicin/capsaicinoids on neural and nonneural tissues is now at hand from a variety of preclinical and clinical studies. However, further research is needed on such issues as long-term effects, including the impact on nervous system regeneration and response to injury in neural and nonneural tissues. Studies needed to be conducted to address the effects of “pepper spray” and capsaicinoids on subjects that are abnormally sensitive or have compromised respiratory physiology. Comparative studies, which focus on inhalation, are needed to enhance the data base and better characterize the pharmacology/toxicology of OC and


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capsaicin/capsaicinoids. Moreover, additional safety evaluation studies of “pepper spray” in animal models of hypersensitivity are needed.

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SAMBAIAH, K. and SATAYANARAYANA, M.N. (1982a) Lipotropic-like activity of red pepper, Journal of Food Science and Technology, 19: 30–35. SAMBAIAH, K. and SATAYANARAYANA, M.N. (1982b) Influence of red pepper and capsaicin on body composition and lipogenesis in rats, Journal of Biosciences, 4: 425–430. SAMBAIAH, K., SATYANARAYANA, M.N., and ROO, M.V. (1978) Effect of red pepper (chillies) and capsaicin on fat absorption and liver fat in rats, Nutrition Reports International, 18: 521–527. SAMBAIAH, K., SRINIVASAN, M.R., SATYANARAYANA, M.N., and CHANDRASEKHARA, N. (1984) Influence of capsaicin on the absorption of amino acids and fat in rats, Journal of Food Science and Technology, 21: 155–159. SANCHEZ, J.F., KRAUSE, J.E., and CORTRIGHT, D.N. (2001) The distribution and regulation of vanilloid receptor VR1 and VR1 5 splice variant RNA expression in rat, Neuroscience, 107: 373–381. SAX, N.I. and LEWIS, R.J. (1989) Dangerous Properties of Industrial Materials, 7th edition, New York: Van Nostrand Reinhold, 2388–2389. SCHUMACHER, M.A., MOFF, I., SUDANAGUNTA, S.P., and LEVINE, J.D. (2000) Molecular cloning of an N-terminal splice variant of the capsaicin receptor. Loss of N-terminal domain suggests functional divergence among capsaicin receptor subtypes, Journal of Biological Chemistry, 275: 2756–2762. SMITH, C.G. and STOPFORD, W. (1999) Health hazards of pepper spray, North Carolina Medical Journal, 60: 150–159. STEFFEE, C.H., LANTZ, P.E., FLANNAGAN, L.M., THOMPSON, R.L., and JASON, D.R. (1995) Oleoresin capsicum (pepper) spray and “in-custody deaths”, The American Journal of Forensic Medicine and Pathology, 16: 185–192. STJARNE, P., LUNDBLAD, L., ANGGERDST, X.X., and LUNDBERG, J.M. (1991) American Journal of Rhinology, 5: 145–151. SURH, Y.-J., and LEE, S.S. (1995) Capsaicin, a double-edged sword: toxicity, metabolism, and chemoprotective potential. Life Sciences, 56: 1845–1855. SUZUKI, T. and IWAI, K. (1984) Constituents of red pepper species: chemistry, biochemistry, pharmacology and food science of the pungent principle of Capsicum species. In: A. Rossi (ed.), The Alkaloids, vol. 23, Orlando, FL: Academic Press, Chapter 4. SUZUKI, T., KAWADA, T., and IWAI, K. (1980) Effective separation of capsaicin and its analogues by reversedphase high performance thin-layer chromatography, Journal of Chromatography, 198: 217–223. SZOLCSANYI, J. (1977) A pharmacological approach to elucidation of the role of different nerve fibers and receptor endings in the mediation of pain, Journal of Physiology (Paris), 73: 251–259. SZOLCSANYI, J. (1980) Effect of pain-producing chemical agents on the activity of slowly-conducting afferent fibres, Acta Physiologica Academiae Scientiarum Hungaricae, 56: 86–89. SZOLCSANYI, J. (1982) Capsaicin type pungent agents producing pyrexia. In: A.S. MILTON (ed.), Handbook of Experimental Pharmacology, vol. 60, Pyretics and Antipyretics, Berlin: Springer-Verlag, pp. 437–478. SZOLCSANYI, J. (1983) Disturbances of thermoregulation induced by capsaicin, Journal of Thermal Biology, 8: 207–212. SZOLCSANYI, J. (1984a) Capsaicin and neurogenic inflammation: history and early findings. In: L.A. CHAHL, J. SZOLCSANYI, AND F. LEMBECK, (eds), Antidromic Vasodilatation and Neurogenic Inflammation, Budapest: Akademiai Kiado, pp.7–25. SZOLCSANYI, J. (1984b) Caspsaicin-sensitive chemoreceptive neural system with dual sensory-efferent function. In: L.A. CHAHL, J. SZOLCSANYI, AND F. LEMBECK (eds), Antidromic Vasodilatation and Neurogenic Inflammation, Budapest: Akademiai Kiado, pp. 27–52. SZOLCSANYI, J. (1987) Capsaicin and nociception, Acta Physiologica Hungarica, 69: 323–332. SZOLCSANYI, J. (1993) Actions of capsaicin on sensory receptors. In: J. WOOD (ed.), Capsaicin in the Study of Pain, New York: Academic Press, pp.1–26. SZOLCSANYI, J. and BARTHO, L. (1981) Impaired defence mechanism to peptic ulcer in the capsaicindesensitized rat. In: G. MOZSIK, O. HANNINEN, AND T. JAVOR (eds) Advances in Physiological Science: Gastrointestinal Defence Mechanisms, vol., 29, Budapest: Akademiai Kiado and Pergamon Press, pp. 39–51.



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DISCLAIMER NOTICE The contents of this chapter do not reflect the position, policy, or position of any Government agency. Responsibility for the contents of this chapter resides only with the authors.


CHAPTER

Chronic Toxicity of Riot Control Agents

8

WOODHALL STOPFORD Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, North Carolina

8.1

INTRODUCTION

Chronic toxicity can be defined as either toxic effects that occur after repeated doses or effects that persist after a single toxic dose. This chapter examines both end-points for the following riot control agents (RCAs): 2-chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS), dibenz[b,f]1:4-oxazepine (CR), oleoresin capsicum (OC) and natural capsaicinoids and two synthetic components of OC, capsaicin and n-nonanoyl vanillylamide (VAN). Studies that were reviewed were those that have been published or are available as unclassified documents for public distribution. Studies that look at the effects of repeated doses in animals or man and persistent adverse effects seen after acute dosing in experimental animals are discussed in this chapter. Persistent adverse effects that have been seen with acute dosing in man are discussed in Chapter 11. For acute and subacute exposures, inhalation doses in terms of concentration time (Ct) in units of mg-min/m3 are given when available. All of the RCAs discussed in this chapter were studied as single chemicals except for those studies looking at chronic effects of capsaicinoids, either from exposures to chili peppers or pepper extracts. Although the described chronic toxic effects associated with exposures to these naturally derived products may be due to their capsaicinoid content, there may be other toxic components of chili peppers that may account for some or all of the noted effects. For instance, Reddy et al. (2001) found that 59% of chili samples they analyzed were contaminated with aflatoxin B1, a chronic liver toxin.

8.2

CN

Although 2-chloroacetophenone (CN) has been used since the First World War, there are limited studies available that have looked at the repeated-dose effects of CN by routes other than inhalation. Effects by other routes of exposure have been demonstrated by looking at adverse effects associated with CN’s use in the field. CN is a strong sensitizer. Persistent effects that occur after single exposure have included eye damage, lung damage, and sensitization.

8.2.1

Inhalation

Repeated inhalation of CN can result in severe lung damage with pulmonary edema and hemorrhage. The damage to liver and kidneys that is seen with high-level exposures may reflect either right heart failure (seen with severe lung damage) or a direct toxic effect of 145 © 2004 by CRC Press LLC

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the liver and kidneys. In subacute and subchronic studies, rodents exposed to 4 mg/m3 for over 6 hours (Ct of 1440 mg-min/m3) or less have few effects other than corneal damage while those exposed to 87.6 mg/m3 for 15 min (Ct of 1314 mg-min/m3) have severe lung, liver, and kidney damage. With chronic exposures at 2 mg/m3 (Ct of 720 mgmin/m3) in rodents, the only exposure-related findings were inflammatory changes of the nose and gastric ulcers, the latter probably related to ingestion with grooming activities. Kumar et al. (1994) exposed mice to CN at 87.6 mg/m3 for 15 min a day for 10 days, for a daily Ct of 1,314 mg-min/m3. After 5 days, the lungs showed diffuse hemorrhage, perivascular swelling, congestion of alveolar capillaries and inflammatory infiltration in bronchi. There was cloudy swelling and centrilobular necrosis of liver cells and coagulative necrosis of renal tubules. At 10 days, more severe lung damage was apparent with, in addition to earlier findings, bronchiolitis and alveolitis. In the kidney, Bowman’s capsules were dilated and had a cuff of inflammatory cells. Findings from several studies on CN have been summarized in an NRC report (NRC, 1984). In one study, 20 guinea pigs and 8 monkeys were exposed to CN for 10 days at Ct values ranging from 2,300 to 4,000 mg-min/m3. It was expected that each daily dose would kill 5–12% of the guinea pigs and none of the monkeys. The total accumulative Ct for this study was 31,445 mg-min/m3. This dose would be expected to kill 70% of guinea pigs and all of monkeys if given at once. Only 5 guinea pigs and no monkeys died. In another experiment, 8 dogs were exposed to CN at daily Ct values of 3,000–7,000 mg-min/m3 for 10 days for total cumulative Ct of 60,000 mg-min/m3. Each daily dose was estimated to be at a level that would kill 12% of dogs and the 10 day dose would be expected to kill most of dogs if given all at once. One dog died. In a third series of experiments 20 guinea pigs, 8 dogs, and 8 monkeys were given 10 consecutive exposures to daily Ct values ranging from 1,300 to 4,200 mg-min/m3. These levels were expected to kill 13–49% of guinea pigs, 3–38% of dogs and 0–70% of monkeys. The total cumulative Ct for this experiment was 88,000 mg-min/m3. If given all at once CN at this level would have expected to kill most animals. Death rates, however, were somewhat lower than would be expected with largest single acute dose. In all that died, death was secondary to lung damage. Pathological changes included pulmonary edema, emphysema, pseudomembrane of the trachea, bronchitis, and bronchopneumonia. The National Toxicology Program (1990a) conducted repeated dose inhalation studies with CN in rats and mice in experiments lasting 14 days, 13 weeks and 2 years. Animals were exposed to CN concentrations ranging from 4.8 to 64 mg/m3, 6 h a day for 14 days for daily Ct values of 1,728–23,040 mg-min/m3. All rats exposed to 19 mg/m3 and higher ( 6,840 mg-min/m3) died during the first week of the studies. During the exposure, rats showed partial closure of the eyelids, lacrimation, and shortness of breath. All mice exposed to 10 mg/m3 or higher ( 3,600 mg-min/m3) died during the first week of the studies. Lacrimation was observed in exposed mice. Rats and mice were then exposed to 0.25 to 4 mg/m3 of CN, 6 h a day, 5 days a week for 13 weeks (Ct values of 90–1,440 mg-min/m3). All rats lived to the end of the studies. Eye irritation and corneal opacities occurred in rats exposed to 0.5 mg/m3 or higher. One of 10 female mice exposed to 4 mg/m3 and 1/10 female mice exposed to 0.5 mg/m3 died before the end of the study. No chemical-related gross or microscopic lesions were observed in rats or mice. In the two-year studies, groups of 60 rats of each sex were exposed to a 0, 1, or 2 mg/m3 CN for 6 hours per day, 5 days per week while groups of 60 mice of each sex were exposed to 0, 2, or 4 mg/m3 with a similar protocol. Death rates in rats was not affected by exposure. In mice survival of females exposed to 2 mg/m3 was significantly decreased. The only significant exposure-related pathological finds in rats were suppurative inflammation, hyperplasia, and squamous metaplasia of the nasal mucosa and, in females, inflammation, ulcers, and squamous hyperplasia of the forestomach. Nose changes were seen in mice as well with squamous metaplasia of nasal mucosa in the high exposure group.


CHRONIC TOXICITY OF RCA

8.2.2 Sensitization Chung and Giles (1972) applied 1 or 2 mg of CN topically (0.5% or 1.0% in acetone) daily to the skin of guinea pigs for induction and challenged 3–4 weeks later with 0.1 ml of 0.2–1.0% CN (0.2–1.0 mg). There was 100% sensitization with positive results seen at both challenge doses.

8.2.3 Acute persistent – eye CN is a severe eye irritant when used as a liquid in eyes at 1% concentration or greater or with exposures to personal defense sprays containing CN in similar concentrations. MacRae et al. (1970) deposited 10–400 g of CN on filter paper using a 1% solution. The treated paper was then placed on rabbit corneas and moistened with trichloroethane every minute for 10 minutes. Eyes were examined for up to 56 days after test. Controls received saline or trichloroethane alone. All control studies were negative. With 10 g of CN there was a moderate to severe response in all rabbits for 7 days with clearing by 35 days. At 25 g of CN there was a moderate to severe (leukoma) response in all rabbits, persisting for 56 days in 3/8 rabbits. At 50 g CN and higher, there was extensive leukoma with persistent abnormalities in all rabbits for 56 days. The authors estimate from these studies that with a Mace sprayed from 6 feet there will be 0.30 g/mm2 cornea taking into account blink reflex. Based on these rabbit studies they estimate that there will be no permanent damage to eyes at CN doses of 1.1 g/mm2. Ballantyne et al. (1975) treated rabbit eyes with 1–10% CN in polyethylene glycol 300, as a solid (0.1–5 mg), and as aerosols (15 min exposure to 360–719 mg/m3 for Ct values of 5400–10,785 mg-min/m3). Applications with 1% CN caused tearing, inflammation of the lids, conjunctival swelling, congestion, corneal epithelial sloughing, iritis, and corneal vascularization. Keratitis was evident at 2% concentrations and higher. Solid CN was even more damaging to the eye than similar amounts in solution. Aerosols of CN did not damage the eye, but irritation of the lids and conjunctivae were persistent. Gaskins et al. (1972) studied the ocular effects of commercial personal defense sprays on rabbits. Results were compared with the treatment with 0.1 mL of a 1% solution of CN. Commercial preparation with 4.3%, but not 2% or less, resulted in severe eye irritation. With direct application of 1% CN to the cornea, permanent scarring sufficient to cause visual impairment was observed. Similar scarring was also observed in monkeys. 10% CN placed in rabbit eyes caused iritis and conjunctivitis lasting longer than 7 days and corneal opacity lasting longer than 55 days. Leopold and Lieberman (1971) cited findings on the eye effects of Mace (1.2% CN) sprayed into the eyes of rabbits and monkeys. From a distance of 6 feet there was no permanent injury to monkeys eyes. Findings at this distance included swelling of corneal epithelium and conjunctiva with minute corneal epithelial defects. Healing was rapid. When rabbits were sprayed from 6 inches, one-third developed a scar in the line of vision. There was also blistering of skin of the eyelids. Weimer et al. (1975) tested two personal defense sprays containing CN on the eyes and skin of rabbits and monkeys. Spraying rabbits with Mace produced conjunctivitis, blepharitis, swelling of eyelids, depilation around eyelids, and patches of red skin at 1–7 days after exposure, with recovery by 14 days without evidence of corneal scarring. Application of 0.1 mL of the liquid to the eyes of rabbits and monkeys resulted in conjunctivitis, blepharitis, and corneal opacity, the latter still evident at 30 days in some rabbits. A second personal defense spray containing 0.96% CN was tested as well. Doses of 0.005–0.2 mL were placed in the eyes of rabbits. At 3 days there was conjunctivitis at all doses. These doses produced marked conjunctival swelling, redness and corneal opacity


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but no iritis, with conjunctival swelling and redness clearing between 15–21 days after exposure. Corneal opacities cleared between 9 and 12 days after exposure. Monkeys were treated with 0.005–0.1 mL in their eyes. Eye effects included blepharitis and conjunctivitis with a corneal ulcer at 0.1 mL in one monkey. At 0.025 and 0.1 mL there was conjunctival swelling, corneal opacities and redness. At the lower dose the corneal opacities disappeared after 5 days. Rabbits were sprayed for 1–5 s from a distance of 1–6 feet. Severe conjunctival swelling and redness occurred in all with corneal opacities in several except for those sprayed for 1 second from 6 feet. Signs were present in most for 21 days and in some at the end of the test at 30 days. A few rabbits eye muscle damage and underlying scar tissue was still present at 30 days after being sprayed in the face.

8.2.4 Acute persistent – inhalation Single inhalation exposures to CN result in severe lung damage at doses of 3,025 mgmin/m3 in or greater in exposed animals with findings similar to those seen in man. Striker et al. (1967a) exposed monkeys to 3,025; 9,251 and 21,699 mg-min/m3 of CN. The lowest dose resulted in emphysema, pulmonary edema and congestion, bronchitis, pulmonary hemorrhage, and atelectasis with all findings clearing by 30 days after exposure. Similar findings were seen at the mid-dose, but emphysema, atelectasis and pneumonia were still present at 30 days after exposure. At the high dose pneumonia, bronchitis, and swelling of larynx were still present at 30 days after exposure. Ballantyne and Swanston (1978) conducted acute inhalation studies with CN in four rodent species. At lethal concentrations, autopsies showed pulmonary edema, congestion, pulmonary hemorrhage, focal necrosis and an acute inflammatory infiltrate of trachea, bronchi and bronchioles. In animals dying after (48) hours there was also evidence of early bronchopneumonia. Those who survived after CN exposure showed scattered pulmonary hemorrhages and congestion of tracheal mucosa. Weimer et al. (1975) tested two personal defense sprays containing CN. With an intratracheal dose of the first spray to dogs, tracheitis and bronchitis were noted within 7 days and persisted for at least 30 days. Dogs (48) were given the liquid from the second personal defense spray intratracheally as well in doses of 0.1–0.5 mL. These treatments resulted in lung congestion, and clearing by 72 h.

8.2.5 Acute persistent – skin With skin exposures to 1% CN or greater, or with exposures to personal defense sprays containing similar concentrations of CN, severe skin damage can result with tissue death. Gaskins et al. (1972) applied 0.5 mL of 1–4% solutions of CN to rabbit skin placed under occlusive dressings for 24 hours. The CN exposures produced redness, slowly developing purpura and a necrotic eschar. Ballantyne and Swanston (1978) applied a 12.5% solution of CN in acetone or corn oil to the skin of rodents under occlusive dressings for 6 hours and then decontaminated with a detergent solution. This treatment resulted in moderate to marked redness and swelling with desquamation at 4 to 7 days after exposure. Ecchymoses with areas of necrosis were present from 24 h to 7 days with scarring noticeable at 14 days after exposure. Biopsies done 3 days after exposure showed extensive necrosis involving the epidermis and collagen of the outer dermis, swelling, and massive neutrophil infiltration. Weimer et al. (1975) tested two personal defense sprays containing CN. The application of liquid from one personal defense spray to the skin of rabbis and monkeys resulted in redness, dermatitis, and necrosis in some animals at 7 days after exposure. Scar



formation and cutaneous lesions persisted in rabbits for at least 30 days. A second defense spray containing 0.96% CN was applied to the skin of rabbits in amounts of 0.025–1.0 mL. Redness, dehydration, and necrosis occurred at all three doses. Necrosis and redness were still evident at 30 days after exposure. Monkeys were treated with 0.025–1.0 mL CN to their skin. There were little or no effects seen at doses below 1.0 mL. With a 1.0 mL application there was marked redness with swelling in some animals. Necrosis was seen in 2 of 8 monkeys when evaluated at 6–8 days after exposure. No lesions were seen at the time of a pathological examination done at 30 days after exposure.

8.3

o-CHLOROBENZYLIDENE MALONONITRILE

o-chlorobenzylidene malononitrile has a lower toxicity than that of CN while at the same time being more irritating. Like CN it is a strong sensitizer.

8.3.1 Eye The National Research Council (1984) described experiments where 0.05–0.2 mL of a 1% CS solution in propylene glycol was placed in the eyes of rabbits and monkeys daily for 5 days. Applications in rabbits produced iritis at all doses. At 0.2 mL severe conjunctival swelling and corneal ulcerations were seen as well. The findings were less severe in monkeys but qualitatively similar.

8.3.2 Inhalation Repeated exposures have been made to CS as an aerosol in both experimental animals and man. Human subjects have been exposed to daily doses of 180 mg-min/m3 without persistent effects. Rodents can receive subchronic exposures to CS at daily doses of 1,800 mgmin/m3 without persistent adverse effects. While chronic exposures to 270 mg-min/m3 result in chronic nose inflammation. One study of repeated exposures to a personal defense spray using CS showed emphysematous changes of the lungs. Colgrave and Marrs (1983) and Marrs et al. (1983a) exposed rats and hamsters to single dose of CS at 480 mg/m3 for 1 hour or 150 mg/m3 for 2 hr (28,800 and 18,000 mgmin/m3). They then observed the animals for 32 months. No unusual tumor risks or other long-term health effects were identified. There were no effects on survival and no material-related toxic effects. Lundberg (1994) cites findings on human subjects exposed to CS aerosol (1–3 mg/m3) for 60 min at a time for 10 exposures over a 14-day period. The only abnormalities seen were acute eye symptoms that dissipated in 15–30 min after each exposure. Punte et al. (1962) exposed dogs to CS for 1 min a day, 5 days a week for 5 weeks and rats for 5 min a day, 5 days a week for 5 weeks. The daily exposure to dogs was 680 mgmin/m3 (cumulative dose 17,000 mg-min/m3). The daily exposure to rats was 3,640 mgmin/m3 (cumulative dose 91,000 mg-min/m3). No dogs and 6/30 rats died during exposure, the latter with cumulative doses of 25,000 and 68,000 mg-min/m3. There were no changes in blood values for dogs for serum electrolytes or creatinine. There were no gross pathological changes in survivors and or non-survivors. Marrs et al. (1983c) conducted repeat-dose inhalation toxicity studies to a 3–4 micron aerosol of CS using male mice, rats, and guinea pigs. They exposed groups of animals for 1 h a day for 120 days. Exposures were to 3, 30, 192–236 mg/m3. Surviving animals were killed approximately 1 year after the start of exposure. Excess mortality was noted in the high-dose groups of all three species. Death during the experiment was related to


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concentration of exposure rather than total dose (Ct). Guinea pigs experienced 46% mortality after receiving a total dose of 71,000 mg-min/m3 in the first month. A pathological study showed acute alveolitis. There were no unusual pathological findings in rats or mice after 12 months exposure in medium or low exposure groups or in surviving animals in the high exposure group. In guinea pigs there was evidence of a chronic laryngitis and tracheitis in the medium exposure group and in high exposure group survivors. The National Toxicology Program (1990b) conducted long term inhalation studies with mice and rats using CS2. Animals were exposed to graded doses of 100 mg/m3 of CS 6 hours/day, 5 days per week for 2 weeks. Compound-related effects included redness, blepharospasm, listlessness, nasal discharge, and mouth breathing. Rats and mice similarly received graded exposures from 0.4 to 6 mg/m3 (maximum daily dose of 2,160 mg-min/m3) for 13 weeks. Compound-related lesions were seen on a pathological examination of the nose of rats including erosions, hyperplasia, squamous metaplasia and suppurative inflammation. Acute inflammation and hyperplasia of the respiratory epithelium were seen in the larynx and trachea of some exposed rats. Compound-related lesions in mice of the nasal passage in mice included squamous metaplasia and inflammation. There was acute inflammation and hyperplasia of the epithelium of the larynx and trachea in mice as well. Rats received similar graded exposures to 0.75 mg/m3 for 2 years and mice to 1.5 mg/m3. Nasal changes in rats included hyperplasia, squamous metaplasia, focal inflammation and proliferation of the periosteum of the turbinate bones. In mice nasal changes included inflammation, hyperplasia, and squamous metaplasia. Debarre et al. (1999) exposed rats repeatedly to respirable aerosols of 5% CS in methyl isobutyl ketone (as used in a personal defense spray) for two exposures separated by 24 h. There was no difference in ventilatory parameters between the first and second exposures. Histological analysis of the trachea, performed at the end of exposures, revealed emphysematous changes of the lungs.

8.3.3 Sensitization Chung and Giles (1972) evaluated contact sensitization with CS by either a topical or intradermal route. About 1 or 2 mg was applied topically (0.5% or 1.0% in acetone) daily during the induction period. After a 3–4 week rest period, animals were challenged with 0.1 mL of 0.2–1.0% CS (equivalent to 0.2–1 mg). There was sensitization at both 0.5% and 1.0% with reactions to all challenge concentrations. Rothberg (1969) treated guinea pigs intradermally and topically with CS, 3 times a week for 3–4 weeks. After a 2–3 week rest, animals were challenged by topical or intradermal applications. Induction solutions of CS ranged from 1 ppm to 1% in polyethylene glycol. Each dilution was given intradermally to 2 guinea pigs. Animals were challenged by intradermal and topical routes to 0.1% CS, a concentration that did not result in redness. Guinea pigs were also induced with topical applications of 0.1% CS in acetone 3 times a week for 3 weeks. After a 2–3 week rest, they were challenged topically with 0.1% CS in 50 : 50 acetone : olive oil. Sensitization occurred at 1, 10, 100 ppm, 0.1% and 1% of CS intradermally and at 0.1% topically. With sensitization reactions to CS included redness, swelling and/or necrosis.

8.3.4 Acute persistent – eye Ballantyne et al. (1974) investigated the toxicity of 0.5–10% CS in polyethyene glycol. With solutions at a concentration of 1% and more, they found inflammation and



swelling of the conjunctiva, iritis, keratitis, corneal vascularization, patchy denudation of corneal epithelium and neutrophilic infiltration of the cornea. The lesions were more severe and lasted longer at higher concentrations. Ballantyne (1979) evaluated the effects of 10% CS in dichloromethane spray discharged from 6 inches into rabbit eyes. This resulted in conjunctival swelling, keratitis, vascularization of cornea, iritis, and blepharitis. The keratitis persistent for 21 days (to end of experiment). There was desquamation of corneal epithelium with massive neutrophil and mononuclear infiltration into the cornea.

8.3.5 Acute persistent – inhalation Striker et al. (1967b) exposed 32 monkeys in groups of 8 to aerosols of CS generated by M7A3 grenades. The authors sacrificed 2 monkeys at 12 h, 72 h, 1 week, and 30 days after each exposure. The monkeys were exposed to 2700, 8500, 28,500 and 80,000 mg-min/m3 of CS. At 80,000 mg-min/m3 4 monkeys died 3–12 h after exposure and an additional death occurred at 96 h after exposure. At 2,700 and 8,500 fright and blinking were the only clinical findings, disappearing in a few minutes after being removed from chamber. At 28,500 mg-min/m3 there was blinking, shortness of breath, coughing, depression, oral and nasal discharges, vomiting, and tearing, peaking 12 hours after exposure and largely resolved by 72 h after exposure. At 80,000 mgmin/m3 there was severe prostration and shortness of breath peaking at 12 h and slowly improving in survivors over next 3 weeks. At 2,700 mg-min/m3 and higher, pathological examination of lungs showed emphysema, atelectasis, pulmonary congestion, extensive pulmonary edema, emphysema, purulent bronchitis, bronchopneumonia, and bronchiolitis. Colgrave and Creasey (1975) exposed 3 groups of rats to 32,000, 60,000, and 90,000 mgmin/m3 and sacrificed animals periodically over the next 2 days. In animals which died, there was severe congestion of the lungs with areas of alveolar hemorrhage and some interstitial edema. The findings were similar but less marked in survivors. Electron microscopic (EM) studies showed fluid accumulation and degeneration of epithelium and endothelium leading to rupture or dissolution of capillary walls. These EM findings are those seen with acute pulmonary edema. Lungs of animals sacrificed 12 h and onwards were normal.

8.3.6 Acute persistent – skin Ballantyne and Swanston (1978) evaluated the application of 12.5% CS in acetone or corn oil under an occlusive dressing for 6 h in a rodent model. Application sites were decontaminated with a detergent solution at the end of the exposure period. This treatment did not result in desquamation but there was focal epidermal necrosis at 3 days with spongiosis and acute inflammatory cell infiltration on a histopathological examination. Swelling and redness were less marked than with CN and only extended somewhat beyond the area of contact. The same effects were seen with either of the solvent. Lesions resolved in 7 days. Weigand et al. (1970) patch tested rabbits and beagles with CS powder. A histological evaluation of the skin lesions resulting from this exposure showed hydropic degeneration of basal cell layer occurring immediately after a 4-h exposure. There was minimal spongiosis of the prickle cell layer noted 24 h later. Prolonged exposure to CS resulted in epidermal necrosis. The finding of the principal damage to the basal cell layer is typical of skin toxicity of alkylating agents.


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8.4 CR Dibenz[b,f]1:4-oxazepine (CR) has been evaluated with repeated-dose studies by various routes. Transient eye effects are seen with repeated dosing at 1–5% concentrations. Chronic exposures to 2,033 mg-min/m3 are associated with few exposure-related changes. High level (5%) treatment of eyes results in iritis and keratitits.

8.4.1 Eye Biskup et al. (1975) dosed rabbits with 0.2 and 0.05 mL 1% CR in a propylene glycol water mixture daily to their eye for 5 consecutive days. The animals were autopsied at 3 and 30 days after dosing. There were no visible signs of eye irritation. One animal had focal corneal clouding at 30 days but a histopathological evaluation was normal in all animals. Rengstorff et al. (1975) applied 0.025 mL of a 5% CR suspension topically to rabbit eyes. Applications were made 5 days a week for 4 weeks and the animals were kept under observation for 60 days. Clinical effects included moderate, transient conjunctivitis. There were no apparent corneal effects on a slit lamp examination with no fluorescein staining. Light and electron microscopic studies done 32 days after the last dosing were negative with no lid or corneal effects.

8.4.2 Inhalation Kumar et al. (1994) exposed mice to CR for 15-min a day at a concentration of 1,008 mg/m3 for 10 days. After 5 days, lungs showed mild intra-alveolar hemorrhage and the liver and kidneys were normal except for patchy congestion of liver and congestion of the kidney. After 10 days of exposure the lungs showed moderate intra-alveolar hemorrhage and congestion of alveolar capillaries, patchy congestion of the liver, and congestion and a few foci of cortical necrosis in kidneys. Colgrave et al. (1983) and Marrs et al. (1983b) describe experiments where 3 groups of 80 hamsters and 3 groups of 80 mice were exposed to CR, 5 days a week for 18 weeks using Molten CR aerosol of a mass median diameter of 2.86 1.17 m. Surviving animals were killed 1 year after the start of exposure. Exposures in this experiment are detailed in Table 8.1. The authors found increased mortality in the highest dose group. No cause for death was ascertained although pneumonitis was present in several affected animals. The only exposure-related finding at autopsy was an increased incidence of chronic inflammation of larynx in mice.

TABLE 8.1 CR exposures to mice and hamsters Total Ct mg-min/m3

Time of exposure minutes

Mean daily Ct mg-min/m3

Mean conc. mg/m3

92,000 183,000 380,000

5.0 8.6 15.8

1,022 2,033 4,222

204 236 267



8.4.3 Ingestion Ballantyne (1977) dosed male rats, female rabbits, and female guinea pigs with CR dissolved in polyethylene glycol 300 daily for 5 days at 10% the LD50 values. Animals were sacrificed 72 h after the last dose. In addition, 10 rabbits received 10% the LD50 dose daily for 10 days and were sacrificed 72 h after the last dose. There were no changes in white blood cell counts, red blood cell indices, bilirubin, creatinine, urea, GGTP or LDH. A pathological evaluation was normal except for acute bronchiolitis in one rabbit and increased peribronchiolar and perivascular lymphoid tissue in the lungs of guinea pigs.

8.4.4 Skin Biskup et al. (1975) applied 0.2 or 1.0 mL of 1% CR under nonocclusive dressings to the skin of rabbits for 5 consecutive days. Animals were autopsied 3 and 30 days after the last exposure. There were no visible signs of skin irritation and no abnormalities were found on histopathology. Marrs et al. (1982) applied 1 mg of CR dissolved in acetone to the skin of C3H and Porton-strain mice in daily applications for 12 weeks (equivalent to 40 mg/kg/day). After a further 80 weeks the animals were sacrificed and examined grossly and histologically. The results were compared with appropriate solvent and untreated controls. No abnormalities were found that could be ascribed to CR. A high incidence of fatty infiltration of the liver in one strain of mice might have been due to exposure to acetone.

8.4.5 Acute persistent – eye Ballantyne et al. (1975) applied 5% and 10% solutions of CR to rabbit eyes. Iritis and keratitis occurred in some rabbits at both concentrations. Keratitis persisted for 3 days on exposure to a 5% solution and for 21 days on exposure to a 10% solution.

8.5 CAPSAICIN Capsaicin has undergone repeat dose testing in humans by both nasal sprays and aerosol inhalation to concentrations of 100 M (30 ppm). Repeated exposures are associated with tachyphylaxis with loss of response for further capsaicin exposures. Chronic ingestion, studies at levels up to 150 mg/kg/day, have shown few exposure-related changes. Treatment of skin with 0.05% capsaicin results in rapidly reversible desensitization to pain.

8.5.1 Eye Shimizu et al. (1984) noted that repeated administration of 1% capsaicin to the eye fails to elicit corneal opacity in adult rats.

8.5.2 Inhalation Philip et al. (1994) administered capsaicin nasal challenges to 8 subjects (4 normal subjects and 4 subjects with perennial allergic rhinitis) every 10 min for 5 doses. Capsaicin, 20 M (0.5 g per spray), when sprayed into the nose, induced burning, nasal


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discharge, and tearing and an increase in total protein content of nasal lavage fluid in those patients with perennial allergic rhinitis. Burning and tearing responses decreased with repeated doses. Geppetti et al. (1993) studied the effects of capsaicin application to the nasal mucosa of 36 human subjects. They found that the application of 50 L of capsaicin (50 nmol or 15 g, 1 mM) produced overt pain. After repeated administrations (once a day for 5–7 days) this effect underwent almost complete desensitization. Marabini et al. (1991) studied the effects of 15 micrograms capsaicin suspended in 100 L (0.49 M) solution in patients with known vasomotor rhinitis. Capsaicin was given 3 times/day for 3 days to each patient by means of a spray delivered to the nasal mucosa. Acute effects induced by the drug included pain and nasal discharge but were no longer observed at the last capsaicin application. Patients recorded their symptoms over a 1-month period. The mean symptom score involving nasal obstruction and nasal secretion was markedly reduced by capsaicin treatment. Morice et al. (1992) evaluated long-term tachyphylaxis to 1-minute capsaicin inhalations at 10 min intervals for 40 min in 10 normal subjects. Cough was attenuated with capsaicin at concentrations of 3, 10, 30, and 100 M. At the highest concentration, cough attenuation was still present at 180 min.

8.5.3 Ingestion Nopanitaya (1973) dosed rats with up to 1 mg/kg bw/day capsaicin for 28 and 56 days. He found this diet was associated with decreased fat absorption based on fat droplet content of duodenal epithelial cells. Nopanitaya (1974) further noted that there were no light microscopic changes in morphology of duodenal mucosa with these studies but that electron microscopic studies showed epithelial cell deterioration. Monsereenusorn (1983) treated rats with 50 mg/kg bw/day capsaicin by gavage or 0.5 gm/kg bw/day capsicum fruit crude extract for 60 days. No correlation between treatment and adverse effects was apparent. The complete blood counts, renal concentration ability and urine assays for glucose, blood, bile salts or lactones were normal. At autopsy, there were no significant pathological findings except for slight redness without hemorrhage in livers and gastric mucosa. Organ weights were no different from controls. Srinivasan et al. (1980) fed groups of 8–10 albino rats 0, 15, 30, and 150 mg/kg of capsaicin a day for 6 months. The authors measured serum proteins, cholesterol and nitrogen balance and performed autopsies at 6 months after dosing with tissues examined histologically. No differences were found in red blood cell, white blood cell, or white blood cell differential counts, or serum protein levels when exposed animals were compared to controls. Total cholesterol levels were reduced in capsaicin-treated rats with significant effects at the 30 mg/kg level. In groups treated with 30–150 mg/kg capsaicin there was some destruction of taste buds and keratinization and erosion of the mucosal layer of the intestinal tract. The large intestine, liver, and kidneys were normal.

8.5.4 Skin – human Anand et al. (1983) found that pretreatment of skin with capsaicin inhibited flare by not wheal responses to substance P, somatostatin, histamine, and vasoactive intestinal polypeptide. The authors applied 1% capsaicin cream in 8 applications over 3 days to human subjects. Burning and redness lessened with each application, disappearing by day 3. Lundblad et al. (1985) investigated whether or not capsaicin pretreatment could block the allergic triple response of itching, wheal and flare on exposure to antigen. They



applied 30 mM (0.9%) capsaicin to an area of abraded skin three times a day for 4 days on 6 volunteers with known rat allergies. The treatment produced a burning sensation and flare reaction but no wheal with the response subsided after 2 to 3 days. On day 5 prick tested with rat antigen produced a triple response in control skin but in treated skin. With treatment the flare was reduced by 95%, itching was much less intense, but there was no change in the wheal response. McMahon et al. (1991) applied capsaicin cream (0.075% or 0.75%), or a vehicle cream, twice daily to the hind paws of rats for 10 weeks. After 10 weeks of capsaicin application, the ability of C fibers to produce neurogenic extravasation was markedly reduced. After 4 weeks and 12 weeks of recovery this ability returned to normal in 0.075% capsaicintreated animals, but remained impaired in the 0.75% group. C fiber function was tested by painting the treated area with 10% mustard oil in olive oil while anesthetized and quantifying neurogenic extravasation with Evans blue dye. The number of dorsal root ganglion cells of the sural nerve did not differ from controls. The neuron cell size, however, was significantly smaller in the capsaicin-treated group. A number of researchers have looked at the effects to human subjects of skin exposures to 0.025–0.075% capsaicin given daily for 7 days to 16 weeks. Treatment is associated with relief of foot pain associated with diabetic neuropathy, relief of pain associated with postherpetic neuralgia, reduced ability to detect heat and respond to histamine (Bernstein et al., 1987; Westerman et al., 1988; Ross and Varipapa, 1989; Simone and Ochoa, 1991). Wallengren and Moller (1986) evaluated the application of 0.1 mL of 0.1% capsaicin in alcohol to forearms over 5 5 cm2 area daily for 3 days. Pain and redness decreased with second application with no reaction to the third application. Treatment decreased flare response to substance P and histamine but not the wheal response. Treatment, however, enhanced noncontact urticaria induced by benzoic acid and allergic reactions when atopics were tested with allergens to which they had known allergies.

8.5.5 Acute persistent – eye Application of 1% capsaicin to rodent eyes results in neurogenic inflammation, depletion of substance P and loss of reactivity to chemical stimuli. These changes remain for at least one week (Fitzgerald, 1983; Buck and Burks, 1986). Winek et al. (1982) treated 3 groups of rabbits, 6 per group with a capsaicin-based pepper sauce. Eyes were treated with 0.1 mL of pepper sauce and the results were compared with the effects of 5% acetic acid, an irritant component of pepper sauce. Corneal damage was assessed at 24, 48, and 168 hours after dosing. Corneal injury scores for the pepper sauce groups were 41.6, 32.5, and 20.8 out of 80 while for the equivalent acetic acid-treated groups the scores were 1.7, 1.7, and 0.8 out of 80. Iris damage was also apparent with pepper sauce treatment. Injury scores were 6.7, 6.7, and 3.3 out of 10 at 24, 48 and 168 h after treatment. With acetic acid treatment the equivalent scores were 1.7, 0.8, and 0 out of 10. The authors suggest that the eye damage was likely, secondary to the capsaicin component of pepper sauce.

8.6 OC Chronic dosing studies have been done with either chili peppers or their extracts by ingestion. Results in some studies differ dramatically from chronic dosing studies with capsaicin with dosing associated with cirrhosis and kidney disease. These results may reflect exposure to a component of chili peppers other than capsaicinoids.


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8.6.1 Ingestion A number of studies have looked at ingestion of capsaicin-containing peppers at doses up to 5 g/kg/day and for periods of up to 5 months. These studies variously reported some destruction of taste buds and keratinization and erosion of the mucosal layer of the intestinal tract (Srinivasan et al., 1980); pronounced histopathological changes of liver cells, massive eosinophilic necrosis, fatty infiltration of hepatocytes, increases in serum transaminase (Lee, 1963); slight glycogen depletion and anisocytosis of hepatocytes (Jang et al., 1992); and no abnormalties (Winek et al., 1982). Studies have also been done with extracts of chili peppers for up to 16 months. Finds have also been variable and have included glomerular degeneration of the kidneys and cirrhosis of the liver (Agarwal and Bhide, 1988); hyperplasia, keratinization and/or dysplasia of tongue, superficial gastritis with infiltration of lymphocytes and plasma cells and chronic gastric ulcers, liver necrosis and fibrosis and tubular degeneration of the kidney (Agrawal and Bhide, 1987); decreased cholesterol absorption with reduction in liver cholesterol and increases in fecal excretion of cholesterol and bile acids (Govindarajan and Sathyanarayana, 1991). Agarwal et al. (1985) dosed hamsters with chili extract equivalent to 50 g of capsaicin to their cheek pouches daily until death. About 23% of the hamsters developed shrunken eyeballs and closing of their eyelids. Vitamin A levels decreased significantly in the liver tissue of chilli-treated groups compared to absolute alcohol-treated and untreated groups. A pathological examination of the eyes of treated hamsters showed that in those without shrunken eyes, there were thickened corneas. In those with eye changes, there was a focal increase in corneal epithelial cells, the iris was adherent to lens, there was disorganization of architecture of retina. The authors felt that it was likely that substance P was depleted from the cornea in treated hamsters with associated loss of protective corneal reflexes, which can result in subsequent eye injury. Schneider et al. (1956) studied the effect of spices on symptoms and rate of healing of 50 patients with duodenal or gastric ulcers. Patients were given antacids, antispasmotics and an ulcer diet plus a spice in a capsule 3 times a day with meals. Patients were dosed with 0.5 gm chili pepper per meal for up to 100 days. One of 3 chili spice patients had considerable heart burn after 60 days, with clearing after the was spice stopped. Enteroscopies before and after ingestion of spices were done. Little or no changes were seen except for moderate redness with chili pepper (2 cases).

8.6.2 Sensitization Winek et al. (1982) applied 0.1 mL of a capsaicin-based pepper sauce to abraded clipped skin of 10 guinea pigs, using a 24-h occlusive dressing, 3 times a week for 9 applications. After a 2 week rest, 0.1 mL was again placed under a 24 h occlusive dressing as a challenge. Skin irritation occurred without sensitization.

8.7 VAN Repeat-dose studies with n-nonanoyl vanillylamide (VAN) have been done to by ingestion. No abnormalities were found with dosing of up to 150 mg/kg/day for up to 6 months except for a reduction in cholesterol. VAN is a severe eye irritant at 0.3%.



8.7.1 Ingestion Govindarajan and Sathyanarayana (1991) report on a study where rats were fed VAN at 0.2% in there diet (equivalent to 70–80 g/kg/day) for 7 weeks. With a high fat diet there was decreased weight gain, decreased liver and serum triglyceride levels, decreases in both total and HDL cholesterol and an increase in hormone sensitive lipase, an enzyme involved in mobilizing adipose fat. At treatment levels of 50 and 500 g/kg/day with high carbohydrate diet there were increases in HDL cholesterol. Srinivasan and Satyanarayana (1989) fed 0.2 mg% VAN (equivalent to 70–80 g/kg/day) to female Wistar rats along with a high fat diet for 11 weeks. Treatment was associated with a lowered adipose tissue weight and also lowered liver and serum triglycerides. The compound elevated total post-heparin plasma lipase and skeletal muscle lipase activities and increased activity of hormone sensitive lipase (involved in mobilization of adipose fat). The increase in the latter indicates the possible mechanism by which capsaicin enhances serum triglyceride uptake by muscle tissue and in turn lowers triglyceride levels. A single dose of capsaicin even at a much higher level failed to lower serum triglycerides emphasizing the necessity of continuous ingestion of capsaicin for exerting its hypolipidemic effect. Posternak et al. (1969) fed rats VAN for 90 days in their diets. Doses averaged 8.36 mg/kg/day in males and 10.33 mg/kg/day for females. Groups of 10–16 male and 10–16 female Charles River CD rats were fed VAN and compared to controls without flavoring supplement. Red blood cell indices, white blood cell counts, BUN, an organ weights were normal. No test-related pathological changes were identified. Srinivasan et al. (1980) fed groups of 8–10 albino rats 0, 15, 30, 150 mg/kg of VAN daily for 6 months. The authors measured serum proteins, cholesterol, and nitrogen balance and performed autopsies at the end of the study with tissues examined histologically. No differences were found in red blood cell, white blood cell or white blood cell differential counts or serum protein levels when exposed animals were compared to controls. Total cholesterol levels were reduced in VAN -treated rats with significant effects at the 15 mg/kg/day level. Histopathological examinations of tissues including the tongue, intestine, liver, and kidneys were normal.

8.7.2 Acute persistent – eye The Committee on Toxicology of Chemicals in Food (2002) report on tests of a VAN solution in the eyes of rabbits. About 0.1 mL of the formulation used in personal defense sprays (0.3% in 50% aqueous ethanol) was placed in rabbit eyes. At 24 and 72 h after treatment there were corneal opacities and iritis. However, the eyes of all the animals were normal by 7 days postexposure.

REFERENCES AGARWAL, R.C. and BHIDE, S.V. (1987) Biological studies on carcinogenicity of chillies in Balb/c mice, Indian Journal of Medical Research, 86: 391–396. AGARWAL, R.C. and BHIDE, S.V. (1988) Histopathological studies on toxicity of chilli (capsaicin) in Syrian golden hamsters, Indian Journal of Experimental Biology, 26: 377–382. AGARWAL, R.C., SARODE, A.V., LALITHA, V.S., and BHIDE, S.V. (1985) Chilli extract treatment and induction of eye lesions in hamsters, Toxicology Letters, 28(1): 1–7. ANAND, P., BLOOM, S.R., and MCGREGOR, G.P. (1983) Topical capsaicin pretreatment inhibits axon reflex vasodilatation caused by somatostatin and vasoactive intestinal polypeptide in human skin, British Journal of Pharmacology, 78(4): 665–669.


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BALLANTYNE, B. (1977) The acute mammalian toxicology of dibenz(b,f)-1,4-oxazepine, Toxicology, 8(3): 347–379. BALLANTYNE, B. (1979) Evaluation of ophthalmic hazards from an aerosol generator of 2-chlorobenzylidene malononitrile (CS), Military Medicine, 144(10): 691–694. BALLANTYNE, B. and SWANSTON, D.W. (1978) The comparative acute mammalian toxicity of 1-chloroacetophenone (CN) and 2-chlorobenzylidene malononitrile (CS), Archives of Toxicology, 40(2): 75–95. BALLANTYNE, B., GAZZARD, M.F., SWANSTON, D.W., and WILLIAMS, P. (1974) The ophthalmic toxicology of o-chlorobenzylidene malononitrile (CS), Archives of Toxicology, 32(3): 149–168. BALLANTYNE, B., GAZZARD, M.F., SWANSTON, D.W., and WILLIAMS, P.T. (1975) The comparative ophthalmic toxicology of 1-chloroacetophenone (CN) and dibenz(b.f)-1:4-oxazepine (CR), Archives of Toxicology, 34(3): 183–201. BERNSTEIN, J.E., BICKERS, D.R., DAHL, M.V., and ROSHAL, J.Y. (1987) Treatment of chronic postherpetic neuralgia with topical capsaicin. A preliminary study, Journal of the American Academy of Dermatology, 17(1): 93–96. BISKUP, R.C., SWENTZEL, K.C., LOCHNER, M.A., and FAIRCHILD, D.G. (1975) Toxicity of 1% CR in propylene glycol/water (20/80), Technical Report EB-TR-75009, Edgewood Arsenal: Aberdeen Proving Ground, MD. BUCK, S.H. and BURKS, T.F. (1986) The neuropharmacology of capsaicin: review of some recent observations, Pharmacological Reviews, 38: 179–226. CHUNG, C.W. and GILES, A.L., Jr. (1972) Sensitization of guinea pigs to alpha-chloroacetophenone (CN) and ortho-chlorobenzylidene malononitrile (CS), tear gas chemicals, Journal of Immunology, 109(2): 284–293. COLGRAVE, H.F. and CREASEY, J.M. (1975) Ultrastructure of rat lungs following exposure to o-chlorobenzylidene malononitrile (CS), Medical Science and Law, 15(3): 187–197. COLGRAVE, H.F. and MARRS, T.C. (1983) Long-term effects of single inhaled doses of 2-chlorobenzylidene malononitrile (CS), British Journal of Pharmacology, 80: 495P. COLGRAVE, H.F., LEE, C.G., MARRS, T.C., and MORRIS, B. (1983) Repeated-dose inhalation toxicity and mutagenicity-status of CR (dibenz-(b.f.)-1,4, oxazepine), British Journal of Pharmacology, 78: 169P. Committee on Toxicology of Chemicals in Food, Consumer Products and the Environment (2002) COT statement on the use of PAVA (Nonivamide) as an incapacitant spray, Department of Health, United Kingdom http:/www.doh.gov.uk/cotnonfood/pava.htm DEBARRE, S., KARINTHI, L., DELAMANCHE, S., FUCHE, C., DESFORGES, P., and CALVET, J.H. (1999) Comparative acute toxicity of o-chlorobenzylidene malononitrile (CS) and oleoresin capsicum (OC) in awake rats, Human and Experimental Toxicology, 18(12): 724–730. FITZGERALD, M. (1983) Capsaicin and sensory neurons – a review, Pain, 15: 109–130. GASKINS, J.R., HEHIR, R.M., MCCAULLEY, D.F., and LIGON, E.W., Jr. (1972) Lacrimating agents (CS and CN) in rats and rabbits. Acute effects on mouth, eyes, and skin, Archives of Environmental Health, 24(6): 449–454. GEPPETTI, P., TRAMONTANA, M., DEL BIANCO, E., and FUSCO, B.M. (1993) Capsaicin-desensitization to the human nasal mucosa selectively reduces pain evoked by citric acid, British Journal of Clinical Pharmacology, 35(2): 178–183. GOVINDARAJAN, V.S. and SATHYANARAYANA, M.N. (1991) Capsicum – production, technology, chemistry, and quality. Part V. Impact on physiology, pharmacology, nutrition, and metabolism; structure, pungency, pain, and desensitization sequences, Critical Reviews in Food Science and Nutrition, 29(6): 435–474. JANG, J.J., DEVOR, D.E., LOGSDON, D.L., and WARD, J.M. (1992) A 4-week feeding study of ground red chilli (Capsicum annuum) in male B6C3F1 mice, Food and Chemical Toxicology, 30(9): 783–787. KUMAR, P., FLORA, S.J., PANT, S.C., SACHAN, A.S., SAXENA, S.P., and GUPTA, S.D. (1994) Toxicological evaluation of 1-chloroacetophenone and dibenz[b,f]-1,4-oxazepine after repeated inhalation exposure in mice, Journal of Applied Toxicology, 14(6): 411–416.



LEE, S.O. (1963) Studies on the influence of diets and lipotropic substances upon various organs and metabolic changes in rabbits on long-term feeding with red pepper. I. Histopathological changes in the liver and spleen, Korean Journal of Internal Medicine, 6: 383–395. LEOPOLD, I.H. and LIEBERMAN, T.W. (1971) Chemical injuries of the cornea, Federation Proceedings of the American Society of Experimental Biology, 30(1): 92–95. LUNDBERG, E.P. (1994) Scientific basis for Swedish occupational standards XV. Consensus report for o-chlorobenzylidene malononitrile. Solna, National Institute of Occupational Health, pp. 56–62. LUNDBLAD, L., LUNDBERG, J.M., ANGGARD, A., and ZETTERSTROM, O. (1985) Capsaicin pretreatment inhibits the flare component of the cutaneous allergic reaction in man, European Journal of Pharmacology, 113(3): 461–462. MARABINI, S., CIABATTI, P.G., POLLI, G., FUSCO, B.M., and GEPPETTI, P. (1991) Beneficial effects of intranasal applications of capsaicin in patients with vasomotor rhinitis, European Archives of Oto-Rhino Laryngology, 248(4): 191–194. MARRS, T.C., GRAY, M.I., COLGRAVE, H.F., and GALL, D. (1982) A repeated dose study of the toxicity of CR applied to the skin of mice, Toxicology Letters, 13(3–4): 259–265. MARRS, T.C., CLIFFORD, E., and COLGRAVE, H.F. (1983a) Late inhalation toxicology and pathology produced by exposure to a single dose of 2-chlorobenzylidene malononitrile (CS) in rats and hamsters, Medicine, Science and the Law, 23: 257–265. MARRS, T.C., COLGRAVE, H.F., and CROSS, N.L. (1983b) A repeated dose study of the toxicity of technical grade dibenz-(b.f.)-1,4 oxazepine in mice and hamsters, Toxicology Letters, 17(1–2): 13–21. MARRS, T.C., COLGRAVE, H.F., CROSS, N.L., GAZZARD, M.F., and BROWN, R.F. (1983c) A repeated dose study of the toxicity of inhaled 2-chlorobenzylidene malononitrile (CS) aerosol in three species of laboratory animal, Archives of Toxicology, 52(3): 183–198. MACRAE, W.G., WILLINSKY, M.D., and BASU, M.B. (1970) Corneal injury caused by aerosol irritant projectors, Canadian Journal of Ophthalmology, 5: 3–10. MCMAHON, S.B., LEWIN, G., and BLOOM, S.R. (1991) The consequences of long-term topical capsaicin application in the rat, Pain, 44(3): 301–310. MONSEREENUSORN, Y. (1983) Subchronic toxicity studies of capsaicin and capsicum in rats, Research Communications in Chemical Pathology and Pharmacology, 41(1): 95–110. MORICE, A.H., HIGGINS, K.S., and YEO, W.W. (1992) Adaptation of cough reflex with different types of stimulation, European Respiratory Journal, 5(7): 841–847. National Research Council (1984) Possible long-term health effects of short-term exposure to chemical agents, vol. 2. Cholinesterase reactivators, psychochemicals, and irritants and Vesicants. US Department of Commerce. National Toxicology Program (1990a) Toxicology and carcinogenesis studies of 2-chloroacetophenone (CAS No. 532-27-4) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). NTP TR-379. National Toxicology Program (1990b) Toxicology and carcinogenesis studies of CS2 (94% o-chlorobenzalmalononitrile, CAS No. 2698-411) in F344 Rats and B6C3F1 Mice (Inhalation Studies). NTP TR-377, http://ntp-server.niehs.nih.gov/LStudies/TR377.html, 2002. NOPANITAYA, W. (1973) Long-term effects of capsaicin on fat absorption and the growth of the rat, Growth, 37(3): 269–279. NOPANITAYA, W. (1974) Effects of capsaicin in combination with diets of varying protein content on the duodenal absorptive cells of the rat, American Journal of Digestive Diseases, 19(5): 439–448. PHILIP, G., BAROODY, F.M., PROUD, D., NACLERIO, R.M., and TOGIAS, A.G. (1994) The human nasal response to capsaicin, Journal of Allergy and Clinical Immunology, 94(6 Pt 1): 1035–1045. POSTERNAK, J.M., LINDER, A., and VODOZ, C.A. (1969) Toxicological tests on flavouring matter, Food and Cosmetic Toxicology, 7: 405–407. PUNTE, C.L., WEIMER, J.T., BALLARD, T.A., and WILDING, J.L. (1962) Toxicologic studies on ochlorobenzylidene malononitrile, Toxicology and Applied Pharmacology, 4: 656–662.


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REDDY, S.V., MAYI, D.K., REDDY, M.U., THIRUMALA-DEVI, K., and REDDY, D.V. (2001) Aflatoxins B1 in different grades of chillies (Capsicum annum L.) in India as determined by indirect competitiveELISA, Food Additives and Contaminants, 18(6): 553–558. RENGSTORFF, R.H., PETRALI, J.P., MERSHON, M.M., and SIM, V.M. (1975) The effect of the riot control agent dibenz(b,f )-1,4-oxazepine (CR) in the rabbit eye, Toxicology and Applied Pharmacology, 34(1): 45–48. ROSS, D.R. and VARIPAPA, R.J. (1989) Treatment of painful diabetic neuropathy with topical capsaicin, New England Journal of Medicine, 321(7): 474–475. ROTHBERG, S. (1969) Skin sensitization potential of the riot control agents CA, DM, CN, and CS in guinea pigs, EATR 4219, Medical Research Laboratory, Edgewood Arsenal, MD. SCHNEIDER, M.A., DELUCA, V., and GRAY, S.J. (1956) The effect of spice ingestion upon the stomach, American Journal of Gastroenterology, 26: 722–332. SHIMIZU, T., FUJITA, S., and IZUMI, K. (1984) Corneal lesions induced by systemic administration of capsaicin in neonatal mice and rats, Naunyn-Schmiedebergs Archives of Pharmacology, 326: 347–351. SIMONE, D.A. and OCHOA, J. (1991) Early and late effects of prolonged topical capsaicin on cutaneous sensibility after neurogenic vasodilation in humans, Pain, 47: 285–294. SRINIVASAN, M.R. and SATYANARAYANA, M.N. (1989) Effect of capsaicin on skeletal muscle lipoprotein lipase in rats fed high fat diet, Indian Journal of Experimental Biology, 27(10): 910–912. SRINIVASAN, M.R., SAMBAIAH, K., and SATYANARAYANA, M.N. (1980) Influence of red pepper and capsaicin on growth, blood constituents and nitrogen balance in rats, Nutritional Reports International, 21: 455–467. STRIKER, G.E., STREETT, C.S., HERMAN, D.F., and HELLAND, D.R. (1967a) A clinicopathologic study of the effects of riot control agents on monkeys. I. Diphenylaminochloroarsine–choroacetophenone (DM–CN) grenade. Medical Research Laboratory, Edgewood Arsenal, MD. EATR 4068. STRIKER, G.E., STREETT, C.S., FORD, D.F., HERMAN, L.H., and HELLAND, D.R. (1967b) A clinicopathologic study of the effects of riot control agents on monkeys IV. o-chlorobenzylidene malononitrile (CS) grenade. EATR 4071, Medical Research Laboratory, Edgewood Arsenal, MD. WALLENGREN, J. and MOLLER, H. (1986) The effect of capsaicin on some experimental inflammations in human skin, Acta Dermato-Venereologica, 66(5): 375–380. Weigand (1970) The cutaneous irritant reaction to agent o-chlorobenzylidene malononitrile III. Histopathology and histochemistry of the irritant reaction in animals. Edgewood Arsenal Technical Report 4451. WEIMER, J.T., OWENS, E.J., and MCNAMARA, B.P. (1975) Toxicological assessment of riot control spray devices and fillings. Edgewood Arsenal Technical Report EB-TR-75047. WESTERMAN, R.A., ROBERTS, R.G., KOTZMANN, R.R., WESTERMAN, D.A., DELANEY, C., WIDDOP, R.E., and CARTER, B.E. (1988) Effects of topical capsaicin on normal skin and affected dermatomes in herpes zoster, Clinical and Experimental Neurology, 25: 71–84. WINEK, C.L., MARKIE, D.C., and SHANOR, S.P. (1982) Pepper sauce toxicity, Drug and Chemical Toxicology, 5: 89–113.


CHAPTER

Reproductive and Developmental Toxicology of Riot Control Agents

9

RUSSELL F. MANKES1 AND KRISTINA M. MANKES2 1 Department of Environmental Health and Safety, Albany Medical College, Albany, NY 12208 2 Department of Medicine, University of Maryland, Baltimore, MD 21201

9.1 INTRODUCTION Critical, modern investigations of riot control agent (RCA)-induced reproductive and developmental toxicology are severely lacking. Despite the widespread use of such agents in both the military and public sectors, published and accessible human gestational exposure data as well as clinical and epidemiological studies of birth outcomes for RCAexposed individuals (occupational, inadvertent, or intentional) are essentially nonexistent. To this date, the few older animal studies that have investigated the reproductive and developmental toxicology of the RCAs have limitations making a comprehensive review difficult. These limitations include: studies that focus only on select agents (CA, BA, DM); those that lack mammalian species (CN, CNS, CNC, CNB); those involving pregnancy in a single species only (CR, rabbit; oleoresin capsicum, rat); and those that do not address both male and female factors (as in the FDA Segment 1 and the multigenerational reproduction studies of the WHO or US EPA). Most RCA formulations (spray or pyrotechnic) rely on complex mixtures (refer to Appendix C). Defense spray formulations contain active ingredient, carriers/solvents, and propellants; the great majority of which are incompletely characterized for reproductive and developmental toxicity. None of the carriers/solvents, propellants, or congeners have been evaluated in combination or interaction with the RCAs. For example, while chloropicrin (an obsolete RCA) has been well characterized for its reproductive toxicology (by virtue of its use as a pesticide) its reproductive and developmental toxicant effects in combination or interaction with chloroacetone in the agent CNC are unknown. Does synergy, potentiation, or additive developmental toxicity occur? How does the vehicle effect the combination? The confounding effect of stress interacting with RCA exposure and on carrier/solvent formulations is not known nor has it been considered in the design or execution of any reproductive developmental toxicity evaluation to date. Clearly, as thin as the classical reproductive and developmental toxicity data are relative to the RCAs; modern evaluations of the potential for neurobehavioral teratogenic effects are essentially nonexistent. As the sensory neurobiology of RCAs is relatively well characterized (see Chapters 5, 6 and 7), the effects of RCAs on late developing CNS and behavioral responses need to be more clearly elucidated (Pellicer et al., 2001). Questions arise relative to species appropriateness in the reproductive and developmental toxicity


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evaluation of the RCAs. Common laboratory species (rats, rabbits, mice) may be relatively insensitive to RCAs effects. To the present, no studies have addressed species selection, relying on the current standards of toxicology practice to select rats and rabbits. It is important that the available toxicokinetic and distribution data (Chapter 4) for the RCAs be considered in selection of the most appropriate species for the reproductive and developmental testing of RCAs.

9.2 MAJOR RIOT CONTROL AGENTS (ACTIVE INGREDIENTS) 9.2.1 Chloroacetophenone Chloroacetophenone is the original MACE®, first synthesized in 1870s (Sidell, 1997). CN has been widely used in civilian and military applications worldwide from the 1920s. CN is a crystalline solid with the odor of apple blossoms and an instantaneous onset of symptoms at exposure levels of 0.3–0.4 mg/m3 (TC50 – eyes/airways) and incapacitation at 20–50 mg/m3. An exposure level of 3,200–8,500 mg-min/m3 is the estimated LCt50 of CN. CN is an SN2 alkylating agent having an affinity for SH groups resulting in enzyme inhibition and protein denaturation. Developmental toxicity studies were done in the early 1960s using chicken embryos. For these, fertilized hens eggs were incubated for 16–18 h (primitive streak stage) or 22 h (head process stage) and explanted. The explanted cultures were then exposed to CN at 0, 0.5, 1, 1.25, 1.6, 2, and 3 mM (in 50% ethanol) for 15–120 min and cultured for an additional 21 h postexposure. Only those embryos exposed to CN at 0.5 mM for 15 min underwent further differentiation. This concentration was then selected for further studies with 91 primitive streak stage embryos and 13 head process stage embryos. Of the 91 primitive streak stage embryos exposed to CN (0.5 mM for 15 min), 21 died (23% mortality). Serious and significant abnormalities afflicted the vast majority of surviving primitive streak stage chicken embryos (n 70) incubated with 0.5 mM CN for 15 min. The abnormalities described included anomalies of the forebrain in 56 (80%), changes in the posterior portion of the brain in 57 (81.4%), neural tube defects in 34 (48.7%), optic vesicle abnormalities in 56 (80%), unfused and fused unflexed vitelline veins in 16 and 27 (22.8% and 38.5%, respectively), abnormal notochord in 14 (20%), abnormal or unformed somites in 27 (39%), and shortened axis length in 89% of the surviving test embryos. All 67 primitive streak stage embryos serving as controls (0 mM CN in 50% ethanol for 15 min) survived (0% mortality). Minor anomalies affecting a minority of the control embryos were observed. These included unfused vitelline veins in 16 (24%), absent optic vesicle in 8 (12%), and shortened axis length in 30% of the control embryos. Of the 13 head process stage embryos exposed to 0.5 mM CN for 15 min, all survived and showed normal development after an additional 21 h incubation postexposure (Lakahai, 1962a). In a mechanistic study to evaluate the effect of various CN concentrations on the morphologic organizing capacity of Hensons node, primitive streak stage chicken embryos were explanted and exposed 0, 0.5, 1.0, or 1.5 mM CN in 50% ethanol for 15 min or to 0.5 mM CN in 50% ethanol for 30 min. Three h post exposure, the Hensons node from the treated explants were dissected and grafted to host primitive streak stage chicken embryos and allowed to continue for 18–20 h postgraft. CN exposure caused a dose-dependent loss of induction. Induction percentages in control graft embryos ranged from 80% to 85%. At the lowest (0.5 mM CN) exposure level for 15 min, 30% of the grafted embryos had an absence of induction. Doubling the CN exposure period to 30 min, increased the loss of induction


REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY OF RCA

to 38% of the grafted embryos. At 1.0 or 1.5 mM CN for 15 min, 60–89% of the grafted embryos had an absence of induction (Lakahai, 1962b). In a subsequent study, Lee and Kalmus (1975) reported that concentrations of CN equimolar to the sulfhydryl-inducing amino acids cysteine and glutathione, blocked the amino acid induction of chick postnodal blastoderm explants. In this report, stage 4 chicken embryos were dissected to remove the postnodal blastoderm specimens that were then grown in culture for 4 days. Only 1 of 12 post nodal blastoderm cultures exposed to 10.2 g CN/ml showed further differentiation in vitro as compared to 3 of 36 control, 30 of 42 cysteine (8 g/ml) or 35 of 48 glutathione (8 g/ml) exposed cultures. In the presence of CN, postnodal blastoderm cultures exposed to cysteine or glutathione did not develop notochord, somite mesoderm, or pulsatile tissue. The lack of modern, mammalian developmental toxicity evaluations with CN is difficult to reconcile with its wide use and potential for human exposure. The studies, recounted here, indicate that CN can affect critical stages of embryonic development when instilled in an alcoholic solution at mM concentrations directly into cultures of hens’ eggs. The relevance of these effects in chicken embryos to human reproductive risk is unknown. CN is widely used in civilian applications and sold in a variety of consumer formulations, routinely resulting in numerous intentional, occupational, or inadvertent human exposures. Despite the wide potential for human exposures at CN levels from the TC50 to the LCT50, no studies of human birth outcomes among workers, civil authorities, or persons exposed to CN have been conducted. Epidemiological evaluations of birth outcomes to male and female employees of CN manufacturers should be undertaken. Personnel employed by civil authorities with potential occupational exposure (police, fire, emergency services) need also to be evaluated. In this population, the confounding effects of stress and heat on CN embryopathy should be considered.

9.2.2

o-Chlorobenzyl malononitrile

o-Chlorobenzyl malononitrile (CS) is a widely used military and civilian RCA now being replaced by the vanilloids in these applications (Sidell, 1997; Olajos and Salem, 2001). CS is a colorless solid with a peppery odor and instantaneous onset of irritating, rubrifacient effects at a threshold level of 0.004–0.023 mg/m3 (eye–airway). The IC50 for CS is considered to be only 3.6 mg/m3 with a LCt50 of 61,000 mg-min/m3. Workplace exposure guidelines for CS suggest a time-weighted average of 0.4 mg/m3, based on its irritative properties. The TCLo (lowest toxic concentration) is given as 6 mg/m3 for 5 min based on studies of pregnant rats exposed continuously from days 6 to 15 of gestation. CS is considered to be cyanogenic but is said to lack reproductive toxicity or embryolethality. Studies by Upshall (1973) that considered multiple species, multiple days and multiple dosing regimens also concluded “CS was not teratogenic or embryolethal.” In this report, Upshall recounted preliminary, unpublished studies with chicken embryos exposed to 1 and 5 mg CS/egg at incubation day 4 that induced no embryolethality or teratogenic effects. In the rat studies, Porton strain SPF rats were given CS either by injection or inhalation during various stages of gestation. Positive (trypan blue), negative (water vapor, Neolite particulate aerosol, or polyethylene glycol (PEG) injection), and stress (recaging) control groups were employed. Multiple exposure paradigms were used. Initially, pregnant rats were exposed to 20 mg/m3 of CS aerosol for 5 min per day (total dose of 1500 mg-min/m3) from days 1 to 21 (staggered) to achieve a totigestational exposure paradigm. In this study, maternal weight gain increase (in grams) was significantly lower (36.41 10.0 vs 47.24 11.21) for CS-exposed rats as compared to controls (percentage of initial weight not expressed). In addition, 16 abnormal litters were seen among the CS-exposed rats versus 11 among the controls.


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Fetal examinations from totigestational CS-exposed dams reported 25 (vs 17 controls) with visceral anomalies affecting a variety of soft tissue organ systems and 11 (vs 1 control) with skeletal anomalies (poor sternebral ossification, rib defect, clubfoot). More (12) fetuses from CS-exposed dams (vs 4 control) in the totigestational study had testicular defects (percentage of males not expressed). Unfortunately, these observations were not further considered. In a “dose–response” paradigm, pregnant Porton strain female rats were exposed by inhalation to 6, 20, or 60 mg/m3 of CS for 5 min each day (total dose of 30, 100, or 300 mg-min/m3/d) for days 6–15 of gestation. Mean fetal weights were significantly decreased (suggestive of intrauterine growth retardation (IUGR)) from CS-exposed dams as compared to concurrent controls (30 mg-min/m3/d to 3.3 0.4 g; 100 mg-min/m3/d to 3.2 0.4 g; and 300 mg-min/m3/d to 3.1 0.4 g vs 3.5 0.4 g for concurrent controls). Maternal body weight gain, although lower than controls for all CS-exposed groups, attained statistical significance only in the low-dose exposure group (30 mg-min/m3/d). The percentage of initial weight gained was not considered. At the 300 mg-min/m3/d exposure level, 16 abnormal litters were seen (vs 13 in controls); at lower exposure levels (30 or 100 mg-min/m3/d), results were similar to controls (11 or 14 abnormal litters, respectively). Fetal examinations from CS-exposed dams found 20 (30 mg-min/m3/d), 15 (100 mg-min/m3/d), and 27 (300 mg-min/m3/d) with visceral anomalies (vs 16 controls) primarily affecting the kidney (hydroureter–hydronephrosis). Examination also yielded 3 (30 mg-min/m3/d), 3 (100 mg-min/m3/d), and 9 (300 mg-min/m3/d) fetuses (vs 1 control) with skeletal anomalies (poor sternebral ossification, rib and vertebral defects, clubfoot, micromelia). More (12) fetuses from CS-exposed (4–30 mg-min/m3/d; 5–100 mg-min/m3/d; and 3–300 mg-min/m3/d) dams (vs 1 control) in the “critical period” gestational study had testicular defects (percentage of males not expressed). In stark contrast to the CS-exposed rats in this study, a positive control group of Porton rat strains administered a single teratogenic dose of trypan blue (50mg/kg on gestation day 8) responded with a marked and significant increase in fetal loss (43.5% vs 6.9% in neutral controls) and a concomitant decrease in mean litter size (8.0 2.2 vs 12.7 2.9 in neutral controls). Of the 151 fetuses from the trypan blue-treated positive controls, 25% were grossly malformed, 36% bore visceral anomalies (including gastroschisis and omphalocele), and 43% had skeletal defects (including vertebral abnormalities and spina bifida). Among pups from negative control groups (Neosil particulate inhalation, water vapor inhalation, and recaging), the only significant difference was found in maternal weight gain, where the increase was lower for the water vapor-exposed (46 9.2 g) or recaged stressed rats (48.1 6.9 g) as compared to untreated (neutral) controls (54.5 10.1 g) Single CS dose “teratology” studies have been reported in which rats were given 20 mg/kg i.p. on day 6, 8, 9, 10, 12, or 14 of pregnancy. Fetal weights were depressed (8%) only from dams given CS (20 mg/kg, i.p.) on gestation day 12. The incidence of anomalous pups from dams given CS was not statistically different from controls. Pups from dams given CS (20 mg/kg) on days 8 and 12 had the highest number of visceral anomalies (30% and 34%, respectively vs 14% in the controls). Like the study described here, the defects found primarily affected the kidney (hydroureter–hydronephrosis). In terms of fetal skeletal anomalies (poor sternebral ossification, rib defects), the greatest number (19%) were also found from dams given CS on gestation day 8. Fetuses from dams given CS on other gestation days (6, 9, 10, 14) or from controls varied from 12% to 21% with visceral (renal) anomalies. In rabbit studies, animals exposed to 20 mg/m3 CS (5 min per day) on days 6 to 20 of pregnancy (total dose 1500 mg-min/m3) had no significant effects on maternal or fetal measures as compared to concurrent controls. Of note, both control and CS-exposed does lost weight during gestation (116 g in controls; 17 g in CS-exposed). Visceral anomalies affecting either the uterus (2 pups with shortened uterine horns) or testis (2 pups with



cryptorchidism) were noted only from CS-exposed does. Skeletal anomalies (sternum and rib defects, arthrogyposis) affected 3 of 75 pups from CS-exposed does. In another “dose–response” paradigm, pregnant New Zealand white rabbits were exposed by inhalation to 6, 20, or 60 mg CS/m3 for 5 min each day (total dose of 390, 1300, or 3900 mg-min/m3) for days 6 to 18 of gestation; controls were exposed to Neosil (particulate) aerosol (60 mg/m3 for 5 min/d) on these same days. No significant effects as compared to concurrent controls were noted in maternal or fetal measures from any group of CS-exposed does. Control and all three groups of CS-exposed does lost weight during gestation (169.5 g – controls; 64–122 g – CS-exposed). Visceral (kinked ureter) and skeletal (sternum, rib) anomalies afflicted similar numbers of pups from control and CS-exposed does. Despite the wide availability of CS formulations for law enforcement, military, and personal defense (refer to Appendix C), no new reproduction or developmental toxicity studies adherent to current FDA, EPA or NTP protocols have been commissioned or reported. Evaluations of early male specific (segment 1) and late gestational effects (segment 3) are particularly needed. Yet even more key to any future study is the concern regarding species selection. Are rats an appropriate species as the above studies elicited no clinical evidence of a CS effect at levels greater than the human TC50 or IC50? Are rabbits, which exhibited depressed weight gains in all groups exposed to both particulates (xeolite) and CS at exposure levels of CS markedly greater than the known human TC50 or IC50 levels, any better? Further research is obviously necessary. Finally, changes in testicular development (rat) and testicular and uterine development (rabbit) after totigestational exposure observed by Upshall (1973) needs to address the question: Is CS androgen inhibitory or estrogenic? In the above studies, Upshall (1973) found no evidence of a classical teratogenic or embryopathic effect of CS when compared to striking response to teratogenic doses of trypan blue. However, the lack of a demonstrable adverse effect of “stress” in this study needs to be reconciled to known, published adverse reproductive effects of stress itself.

9.2.3 Oleoresin capsicum (“pepper spray”) Oleoresin capsicum (OC) and its major component (capsaicin) are rapidly replacing CN and CS in both military and civilian riot control formulations. These neurophysiologically active natural products are available in formulations enriched to anywhere from 500,000 to 2,000,000 Scoville Heat Units (SHUs) – hot peppers range from 0 for bell peppers to 300,000 for some habanero peppers. Oral doses of aqueous Capsicum frutescens (Cf) solution and low capsaicin (8-methyl-n-vanillyl-6-nonenamide) during gestation produces an increase in the thermonociceptive escape response latency of rat offspring. Addition of 10%, 25%, and 50% Cf to the food of gestating rats causes a dose-dependent modification of flexion reflex latency and the latency of appearance of antianalgesic behaviors expressed as paw lick and escape response using the hot plate test (53C to 90.5C). Animals (Cf, 25% group) tested 55 days after the first test exhibited latencies similar to controls, which suggests that the process is reversible (Pellicer et al., 2001). In another study, pregnant rats were injected with single 10% alcoholic or 10% Tween solubilized doses of 0 or 50 mg OC/kg on gestation days 14, 18 or 20, or 2 doses of 50 mg OC/kg on days 15–16 or 16–17 of gestation. Stunting (significantly reduced crown rump length) was noted in pups from dams given 50 mg OC/kg on gestation day 18. All other measured reproductive and developmental parameters from OC-exposed pups were comparable to controls. Histochemical analysis of spinal cord (substantia gelatinosa of the


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dorsal root) acid phosphatase staining revealed a marked reduction related to intrauterine OC exposure on gestation day 16–17. Recovery was not noted even after 60 days of postnatal development. Behavioral analysis of pup activity revealed a 40% depression in capsaicin-exposed animals (Kirby et al., 1982). In a study addressing reproductive effects, capsaicin, administered intraperitoneally to adult male mice at doses of 0.4, 0.8, or 1.6 mg/kg/d on 5 consecutive days, did not induce significant alterations in epididymal weights, caudal sperm counts, testicular weights or testicular histology. In the sperm morphology assay, sperms at 1, 3, 5, and 7 weeks did not reveal any treatment-related increase in the incidence of sperm-head abnormalities (Narasimhamurthy and Narasimhamurthy, 1988).

9.3 MINOR COMPONENTS AND HISTORICAL AGENTS Like the “big three” riot control agents, CS, CN, and OC, the specifics and reproductive and developmental toxicities of lesser-known and historically used RCAs are equally elusive. Three of the more notable exceptions to this rule are adamsite (DM), dibenz(b,f )1:4-oxazepine (CR), and chloropicrin (military designation PS).

9.3.1 Adamsite No information regarding the reproductive or developmental toxicity of the arsenic containing compound adamsite is available (Sidell, 1997; Olajos and Salem, 2001). However, the reproductive and developmental effects of arsenic and organic arsenical compounds have been extensively reviewed by the ATSDR (2000b). It is stated that “there is no convincing evidence that inhaled or ingested inorganic arsenic can injure pregnant women or their fetuses” (ATSDR, 2000b). Studies in animals show that large doses of arsenic that cause illness in pregnant females can also cause low birth weight, fetal malformations, and even fetal death. The oxidation state of arsenic determines the teratogenic potential of its inorganic compounds: trivalent (III) arsenic compounds possess greater teratogenic potential than pentavalent (V) compounds. Arsenic can cross the placenta and has been found in fetal tissues. In addition, arsenic is found at low levels in breast milk (ATSDR, 2000b). In vitro studies of inorganic arsenic have shown that arsenic is embryotoxic and teratogenic. Arsenic significantly impairs preimplantation development in the mouse blastocyst (Hanna et al., 1997). Mouse embryo culture (Tabocova et al., 1996) found a gestational age dependent disruption in neural tube closure, optic and otic development forebrain. Neural tube cell cycle disruption in arsenic treated postimplantation mouse embryos was also reported by Wlodarczyk et al. (1996). Organic arsenicals MMA and DMA affect fetal development (malformed palate, reduced fetal weight, delayed ossification, increased fetal mortality) in rats and mice (DMA – Rogers et al., 1981) and male fertility (MMA – Prukop and Savage 1986). In humans, Lugo et al. (1969) found ingestion of inorganic arsenic at 30 weeks of gestation caused premature delivery of a live female infant (2 pounds, 7 ounces; 1-min Apgar 4). The child died 11 h later after a progressive deterioration in clinical condition; high arsenic levels were found in the infant’s liver, kidney, and brain. Hamster dams dosed continuously with arsenate and exposed to short-term hyperthermia produced a greater percentage of malformed offspring than did hamster dams dosed with arsenate alone. Hamsters receiving both treatments possessed elevated arsenic



concentrations in the maternal blood and placentas immediately after cessation of the hyperthermic insult. Blood levels of arsenic were the same as those of animals not receiving the heat treatment within several h post-hyperthermia; however, arsenic concentrations remained elevated in placentas, the duration being dependent on the dose of arsenate (Hanlon and Ferm, 1986).

9.3.2 Dibenz[b,f ]1:4-oxazepine Dibenz[b,f]1:4-oxazepine is an odorless, persistent, relatively new RCA, first synthesized by the British in 1962 for military use (Sidell, 1997; Olajos and Salem, 2001). No civilian applications are commercially available. CR was administered to gravid rats and rabbits as an alcoholic particulate (0.9–3.5 M) at aerosol concentrations of 0, 2, 20, and 200 g CR/m3 for 5 min from gestation day 6 to 15 (rat) or 6 to 18 (rabbit). No adverse effects were elicited. Pregnant rats given intragastric (i.g.) doses of 0, 2, 20, or 100 mg CR in propylene glycol on days 6, 8, 10, 12, and 14; or i.g. doses of 400 mg CR in propylene glycol on days 7, 10, or 13 of gestation suffered no adverse reproductive or developmental effects. Embryolethality (significant increase in fetal loss) without a decrease in live pups was only elicited in gravid rabbits given 15.8 mg CR in polyethylene glycol/kg on days 14, 15, and 16 (Upshall, 1974).

9.3.3 Chloropicrin Unlike all the previously described agents, chloropicrin, in its capacity as an irritating soil fumigant, has undergone extensive EPA mandated testing for pesticide registration, making its discussion here extremely valuable. In its capacity as an active ingredient, PS is added to CN and chloroform at a level of 38.4% to make riot control agent CNS. The IC50 for agent CNS is given as 60 mg-min/m3 with a LCt50 of 11,400 mg-min/m3. PS has a workplace occupational exposure limit of 0.7 mg/m3 as a time-weighted average while the general populace has a recommended limit of 0.67 mg PS/m3. It has been reported to cause fetal hypoxia/anoxia due to maternal methemoglobinemia. Chloropicrin (99% purity) was given to rats at 0, 0.5, 1.0, and 1.5 ppm for 6 h/day 7 days/week for 2 generations through weaning of F2 pups. Both generations of females and F1 males showed transitory body weight decreases at exposures greater than 1.0 ppm. The females of the F1 generation had a significant decrease in food consumption at the 1.5 ppm exposure level on days 0–20. Females, primarily F0, were found to have gross and microscopic pulmonary pathology at exposure above 1.0 ppm. No treatment-related effects were observed in pups at any dose. No adverse reproductive effects were seen at any exposure level (Schardein, 1994). In another study, rats given 0, 0.4, 1.2, and 3.5 ppm chloropicrin (6 h/day) during days 6–15 of gestation decreases in body weight, body weight gain and food consumption and increased clinical signs of distress at the highest (3.5 ppm) exposure level. Fetal skeletal variations were significantly increased only on a per pup but not on a per litter basis at the 1.2 and 3.5 ppm level or greater (Schardein, 1993). New Zealand White Rabbits were exposed to 0, 0.4, 1.2, and 2.0 ppm chloropicrin (99% purity) by whole body inhalation exposure on days 7–20 of gestation. Fetal evaluations were performed on day 29 of gestation. At the highest exposure level (2.0 ppm), decreases in body weight, body weight gain, and food consumption were observed. The animals had increases in clinical signs of distress, abortions, and mortality occurred at levels of 1.2 ppm or above. Fetal developmental variations were increased from dams exposed to 2.0 ppm of chloropicrin (York, 1994).


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9.4 COMMONLY USED CARRIERS/SOLVENTS 9.4.1 Methylene chloride Methylene chloride (CAS # 75-09-2) may be used up to 84% of an RCA formulation. The reproductive and developmental effects of methylene chloride have been extensively reviewed by the ATSDR (2000a). There have not been any reports of a connection between methylene chloride exposure during pregnancy and birth defects in humans. In rats, methylene chloride has been shown to cross the placenta. One study found no adverse effects on reproduction in rats exposed to concentrations up to 1,500 ppm of methylene chloride for two generations (Nitschke et al., 1988). In dominant lethal tests involving male mice exposed to 200 ppm methylene chloride for up to 6 weeks, no microscopic lesions were found in the testes (Raje et al., 1988). Uterine, ovarian, and testicular atrophy was observed in rats and mice exposed to vapors of methylene chloride (4,000 ppm) for 2 years (NTP, 1986), but the authors considered this effect to be secondary to malignant hepatic and alveolar neoplasms. In a study examining the relationship between birth weights and environmental exposures to methylene chloride from Kodak manufacturing processes in Monroe Country, New York, no significant adverse effects on birth weight were found among 91,302 single births from 1976 through 1987 (Bell et al., 1991). A study in rats demonstrated that methylene chloride crosses the placental barrier (Anders and Sunram, 1982). No treatment-related visceral abnormalities were reported in fetuses of mice and rats exposed to 1,250 ppm of methylene chloride during gestation, but an increase in the incidence of minor skeletal variants (e.g. delayed ossification of sternebra or extra sternebrae) was observed in both species; rats also exhibit an increased incidence of dilated renal pelvis. A maternal effect of increased liver weight was observed (Schwetz et al., 1975). When rats were exposed to 4,500 ppm, maternal liver weights increased and fetal body weights decreased, but teratogenic effects were not observed and viability and growth were not affected (Bornschein et al., 1980; Hardin and Manson, 1980). Wheel running activity and avoidance learning were not affected in rats born to dams exposed prior to and/or during gestation to methylene chloride at 4,500 ppm (Bornschein et al., 1980). Longer-term exposure (for two generations) to concentrations of 1,500 ppm of methylene chloride did not affect neonatal survival or neonatal growth in rats (Nitschke et al., 1988). Although fetal body weights were decreased, the absence of other fetotoxic effects, major skeletal variants, or significant embryolethality suggests that developmental toxicity is not a major area of concern following exposure to methylene chloride (ATSDR, 2000a).

9.4.2 Methyl isobutyl ketone Methyl isobutyl ketone (MIBK) (CAS # 108-10-1, C6H12O) is a nephrotoxic CS excipient, widely used in UK formulations (Fraunfelder, 2000). MIBK was evaluated for developmental toxicity in a relatively modern (1987) study in 2 rodent species (rats and mice) using multiple inhalation exposure levels (6, 20, and 60 times the human TLV) on gestation days 6–15. Maternal toxicity (clinical signs of intoxication, decreased body weight and food consumption, decreased body weight gain, and increased relative kidney weights) and fetotoxicity (pup body weight depression and ossification defects) were observed in both species at 3,000 ppm, but not at 300 or 1,000 ppm. Significant reductions in fetal weight and ossification in the rat at 300 ppm were thought to be related to litter sizes and were not considered treatment related. No evidence of teratogenicity in either species was elicited, even at the maternally toxic exposure concentration of 3,000 ppm. In mice, maternal effects of



3,000 ppm of MIBK were more profound and included death (12.0%, 3/25 dams) and increased absolute and relative liver weights. Fetotoxicity at this dose level in mice also included an increase in dead fetuses as well as reduced fetal body weights and ossification defects. No treatment-related malformations were seen in either species at any exposure concentration tested. There was no evidence of treatment-related maternal, embryo, or fetal toxicity (including malformations) at 1,000 or 300 ppm in either species (Tyl et al., 1987). MIBK is known to potentiate the hepatic toxicity of haloalkanes (CCl4) and the neurotoxicity of n-hexane, presumably by its action on the microsomal mixed function oxidase system (cytochrome P450). Others have reported MIBK affects the toxicity and response to commercial incapacitant (CS) sprays. No studies have evaluated the developmental toxicity CS and MIBK given in combination mimicking commercial incapacitant (CS) sprays.

9.4.3 Isopropanol Isopropanol (2-propanol; CAS # 67-63-0) constitutes greater than 5% of Mace Pepperfoam 10% and Water Based Pepper Spray formulated by Mace Security International of Bennington VT and 64% of CAP-Stun pepper sprays formulated by Zarc International, Inc. of Gaithersburg MD. A two-generation reproduction study in rats of isopropanol’s effects showed that the first generation offspring of treated rats had early growth retardation, indicating a fetotoxic but no teratogenic effect (Clayton and Clayton, 1982). A developmental study in rats exposed pregnant dams (15/group) to 0, 3,500, 7,000, or 10,000 ppm isopropanol 7 h/day on gestation days 1–19 (Nelson et al., 1988). At the two highest exposure levels, feed intake (weeks 1 and 2 of exposure) and maternal body-weight gain were reduced. Narcosis was evident only at the 10,000 ppm level. Increased fetal resorptions and reduced fetal weights (59% of controls) occurred at the highest exposure level. Fetal weights were also significantly reduced (85% of controls) at 7,000 ppm. A slight reduction in fetal weight (96% of controls) occurred at 3,500 ppm but was significant in the sense that a dose-dependent relationship in fetal weight reduction was present across all exposed groups. Skeletal malformations (primarily rudimentary cervical ribs) were seen only in the presence of maternal toxicity at the two highest exposure levels. No detectable teratogenic effects were observed in the 3,500 ppm group. The authors noted that the developmental effects at 3,500 ppm were considered very slight, indicating that this exposure level is close to the LOAEL for isopropanol. In a developmental study, pregnant rats (gavaged with either 0, 400, 800, or 1,200 mg isopropanol/kg on gestation days 6–15) or rabbits (given 0, 120, 240, or 480 mg isopropanol/kg on gestation days 6–18) showed no differences in reproduction indices or in fetal development. No teratogenic effects were seen in either species (Tyl et al., 1994). In another developmental study performed to investigate neurotoxicity, Bates et al. (1994) found no effects on fetal developmental indices at the dose levels of 0, 200, 700, or 1200 mg isopropanol/kg. Developmental neurotoxicity, in the form of motor activity, auditory startle, and active avoidance tests, was not found at any dose of isopropanol.

9.4.4 Propylene Glycol Propylene Glycol (CAS # 57-55-6) constitutes up to 20% of Mace formulated by Mace Security International of Bennington VT. The reproductive and developmental effects of propylene glycol have been extensively reviewed by the ATSDR (1997d). It was reported that no studies were located regarding reproductive effects in humans after inhalation exposure to propylene glycol. Animal studies however were reviewed. Rats exposed


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continuously to a concentration of 55–112 ppm propylene glycol for 18 months showed no adverse effects on the ability to produce live young, or on survival of the offspring (Robertson et al., 1947). Multigeneration exposure to mice of 0.0%, 1.0%, 2.5%, 5.0% propylene glycol in drinking water was without adverse effect (NTP, 1985). Intraperitoneal injections of 100 mg PG/kg on day 11 or 15 to pregnant mice caused increased fetal mortality (e.g. dead and/or resorbed implants per total number of implants – day 11) or stunted fetal growth (day 15) (NIOSH-RTECS, 1999).

9.5 MINOR CARRIERS/SOLVENTS AND CARRIERS/SOLVENTS OF HISTORICAL INTEREST 9.5.1 Iminodiethanol 2,2-iminodiethanol (CAS # 111-42-2) constitutes greater than 5% of Mace Water Based Pepper Spray formulated by Mace Security International of Bennington VT. Animal studies summarized by the Registry of Toxic Effects of Chemical Substances (RTECS-NIOSH) indicate some minor adverse effects in rats and rabbits at extremely high oral or transcutaneous dose levels. Paternal effects (including sperm morphology, motility, and count) were elicited after oral exposure of rats to ~18 g/kg for 14 days (NTP Technical Report NIH-92-3343). For the transcutaneous route, rats exposed to 15 gm/kg from days 6 to 15 of pregnancy displayed “other effects on female” and “other postnatal measures or effects.” For rabbits, other effects on the female were elicited by transcutaneous doses of ~4.5 g/kg from days 6 to 18 of gestation (Marty et al., 1999).

9.5.2 Limonene Limonene (CAS # 5989-27-5) constitutes up to 20% of Mace formulated by Mace Security International of Bennington VT. Limonene is easily taken up in the blood (high partition coefficient blood/air 42) at the alveolus (Falk et al., 1990). The average net uptake of d-limonene was 65% in volunteers exposed to the chemical at concentrations of 450, 225, and 10 mg/m3 for 2 h during light physical exercise (Falk-Filipsson et al., 1993). Limonene is rapidly distributed to different tissues in the body and is readily metabolized (1.1 L/kg/h blood clearance) (Falk-Filipsson et al., 1993). In rats, the tissue distribution of radioactivity was initially high in the liver, kidneys, and blood after the oral administration of [14C] d-limonene (Igimi et al., 1974); however, negligible amounts of radioactivity were found after 48 h. Limonene has been detected, but not quantified, in the breast milk of non-occupationally exposed mothers (Pellizzari et al., 1982). In rats, the oral administration of d-limonene (2869 mg/kg body weight per day) on days 9–15 of gestation resulted in decreased body weight and deaths among the dams. Delayed ossification and decreased total body and organ weights (thymus, spleen, and ovary) were observed in the offspring (Tsuji et al., 1975). In mice, the oral administration of d-limonene (2869 mg/kg body weight per day) on days 7–12 of gestation resulted in reduced growth in the mothers and a significantly increased incidence of skeletal anomalies and delayed ossification in the offspring (Kodama et al., 1977a). The oral administration of d-limonene (250, 500, or 1000 mg/kg body weight per day) to rabbits on days 6–18 of gestation had no dose-related effects on the offspring. At the highest dose, there were some deaths and reduced weight gain among the dams; at the intermediate dose, growth was decreased (Kodama et al., 1977b).



9.5.3 Dipropylene glycol monomethyl ether Dipropylene glycol monomethyl ether (PGME) (CAS # 34590-94-8) constitutes up to 30% of Mace formulated by Mace Security International of Bennington VT. No reports of reproductive or developmental effects of dipropylene glycol monomethyl ether were found. A study of the reproductive effects of exposure to high concentrations of PGME in rats was reported by the American Chemistry Council Propylene Glycol Ethers Panel. No adverse fertility or reproductive effects were observed at 1,000 ppm PGME or lower exposures. Decreased female fertility and reproductive effects were found only at the highest exposure concentration tested, 3,000 ppm PGME. These effects were associated with general toxicity and apparent resultant nutritional stress encountered by the mothers and offspring at this high concentration of PGME and not thought to be due to direct toxicity to reproductive organs.

9.5.4 Mineral oil Mineral oil (CAS # 8012-95-1) or light lubricating oil constitutes greater than 90% of the CS agent NAPA#765-1787 Qualco#993-C Tear Gas formulated by Qualco Products of Fanwood NJ or the Paralyzer series of CS agents (W207, WKR X621) formulated by the United Defense Industries of Phoenix AZ. No reports of reproductive or developmental effects of either mineral oil or light lubricating oil were found. The ATSDR has published extensive reviews of the health effects of other petroleum and mineral oils: Fuel Oils (CAS #’s 8008-20-6, 70892-10-3, 68476-30-2, 68476-34-6, and 68476-31-3) see ATSDR, 1995a; Jet Fuels JP-4 and JP-7 (CAS # 50815-00-4) see ATSDR, 1995b; Jet Fuels JP-5 and JP-8 (CAS # 8008-20-6) see ATSDR, 1998; Mineral Oil (CAS # 8002-05-9) see ATSDR, 1997c; and Petroleum Hydrocarbons (TPH) see ATSDR, 1999.

9.5.5 Cyclohexanone and glyceryl triacetate Cyclohexanone (CAS # 108-94-1) and glyceryl triacetate (CAS # 102-76-1) are excipients of CS Pepper Fog-CS Special formulated by the Smith & Wesson Chemical Co, Inc of Rock Creek OH. No adverse reproductive effects are noted in MSDS supplied by the manufacturer or in the open literature. Cyclohexanone is reported to have been investigated as a tumorigen, mutagen, and reproductive effector. No adverse effects are reported in the MSDS. Reproductive or developmental toxicity studies with glyceryl triacetate have not been reported.

9.5.6 Benzene Benzene (CAS # 71-43-2, C6H6) and carbon tetrachloride (CAS # 56-23-5, CCl4) each constitute 45% of the riot control agent CNB (active ingredient chloroacetophenone). Benzene crosses the placenta and has adverse reproductive and developmental effects in mammalian species (ATSDR, 1997b). Murray et al. (1979a) showed that inhalation of 500 ppm benzene for 7 h/day on days 6–15 and days 6–18 of gestation in mice and rabbits, respectively, induced minor skeletal variations. Tatrai et al. (1980) demonstrated decreased fetal body weights and elevated liver weights in rats exposed throughout gestation to 150 mg/m3 (47 ppm). Kuna and Kapp (1981) found direct teratogenic effects measured as decreased crown-rump length, exencephaly, and angulated ribs in rats when pregnant females were exposed 6 h/day during days 6–15 of gestation to a concentration of 500 ppm.


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In this study, a concentration of 50 ppm during gestation resulted in lower fetal weights measured on day 20 of gestation. No fetal effects were noted at an exposure of 10 ppm (32 mg/m3). Coate et al. (1984) exposed groups of 40 female rats to 0, 1, 10, 40, and 100 ppm (0, 3.24, 32.4, 129.6, or 324 mg/m3) benzene for 6 h/day, 5 days a week, during days 6–15 of gestation. In this study, teratology evaluations and fetotoxic measurements were done on the fetuses. A significant decrease was noted in the body weights of fetuses from dams exposed to 100 ppm (324 mg/m3). No effects were observed at a concentration of 40 ppm (129.6 mg/m3). Keller and Snyder (1986) reported that exposure of pregnant mice to concentrations as low as 5 ppm (16 mg/m3) benzene on days 6–15 of gestation (6 h/day) resulted in bone-marrow hematopoeitic changes in the offspring that persisted into adulthood. However, the hematopoeitic effects (e.g. bimodal changes in erythroid colonyforming cells) in the above study were of uncertain clinical significance. In a similar, later study, Keller and Snyder (1988) found that exposure of mice in utero to 20 ppm (64 mg/m3) benzene on days 6–15 of gestation resulted in neonatal suppression of erythropoietic precursor cells and persistent, enhanced granulopoiesis. This effect was considered significant bone-marrow toxicity by the authors. No hematotoxicity was seen in this study at 10 ppm (32 mg/m3).

9.5.7 Carbon tetrachloride and chloroform Carbon tetrachloride (CAS # 56-23-5, CCl4), also present in agent CNB, is excreted in breast milk and is reported to have adverse reproductive and developmental effects in mammalian species. The reproductive and developmental effects of carbon tetrachloride has been extensively reviewed by the ATSDR (1994). No studies have been cited regarding reproductive or developmental effects in humans after dermal or inhalation exposure to CCl4. Two related epidemiological studies using the same birth outcome and drinking water exposure data bases from certain areas in New Jersey have been reported (Bove et al., 1992a, 1992b). CCl4 exposures were estimated and concentrations in the drinking water of greater than 1 ppb were said to be related to adverse developmental outcomes (including low birth weight, small for gestational age, central nervous system/neural tube defects, and cleft-lip or cleft-palate. In rats that inhaled CCl4 vapors for three generations, there was a decrease in fertility in animals exposed to concentrations of 200 ppm or higher (Smyth et al., 1936). Since both sexes were exposed, it was not possible to determine if this was due to effects on males, females, or both. Moderate to marked degeneration of testicular germinal epithelium has been seen in rats exposed repeatedly to 200 ppm or higher for 192 days (Adams et al., 1952). Rats exposed to 300 or 1,000 ppm CCl4 for 7 h/day on days 6–15 of gestation had significant decreases in fetal body weight, crown-rump length, and sternebral ossification (Schwetz et al., 1974b). Chloroform (CAS # 67-66-3, CHCl3) constitutes 39% of the relatively obsolete riot control agent CNC (chloracetophenone in chloroform). It is excreted in breast milk and has adverse reproductive effects in rats. The reproductive and developmental effects of chloroform has been extensively reviewed by the ATSDR (1997a). Bove et al. (1995) studied the effects of drinking-water consumption on birth outcome. Exposure to total trihalomethane levels 0.l ppm resulted in a 70.4 g reduction in mean birth weight among term babies, increased odds ratio for low birth weight among term births (1.42), for reduced size at gestational age birth (1.50) and for oral cleft defects (3.17). In addition, levels 0.08 ppm resulted in central nervous system defects (2.59) and neural tube defects (2.96).



Kramer et al. (1992) evaluated the human developmental effects of chloroform in drinking water. Infants studied were divided into three groups based on drinking water chloroform level: group 1 – 0 chloroform in drinking water, group 2 – 1–9 g/L chloroform, and group 3 – more than 10 g/L. The relative risk of intrauterine growth retardation was 80% higher and for low birth weight 30% higher in group 3 infants as compared to the zero exposure group. Group 2 infants (1–9 g/L) had an elevated risk of Intrauterine growth retardation (IUGR) of 30%. The authors considered that there is an increased risk of intrauterine growth retardation associated with CHCl3. CHCl3 induces fetotoxicity and teratogenicity in experimental animals. Rats exposed during gestation had delayed ossification and wavy ribs (30 ppm), acaudate fetuses with imperforate anus and missing ribs (100 ppm), and decreased fetal body weight and crown-rump length as well as increased fetal resorptions (300 ppm) (Schwetz et al., 1974a). Slight growth retardation of live rat fetuses was observed at 30 ppm without major teratogenic effects (Baeder and Hofmann, 1988). The offspring of mice exposed to 100 ppm CHCl3 during gestation had increased incidences of cleft palate, decreased ossification, and decreased fetal crown-rump length (Murray et al., 1979b). The observed malformations occurred in the fetuses that were exposed during organogenesis (days 8–15). Increased resorptions were observed in dams exposed during days 1–7. In another study using relatively higher doses, female Sprague–Dawley rats were exposed to 0, 942, 2,232, or 4,117 ppm chloroform 8 days during Gd 7–14, for 1 hour a day. The number of resorptions was enhanced (45% resorptions) and average fetal body weights declined in the highest exposure group only, with no adverse effects noted in the 2,232 ppm and lower doses. The average fetal weight was decreased at the highest dose. No gross teratologic effects or anomalies in ossification were observed in the offspring of exposed dams (Newell and Dilley, 1978). In addition to the reproductive effects described here, a significant increase in the percentage of abnormal sperm was observed in mice exposed to 400 ppm CHCl3 for 5 days (Land et al., 1979). In males, groups of 10–12 male rats (strain not reported) were exposed to 0, 25, 50, or 85 ppm chloroform for 6 months. Adjusted testicular weights in the 50 and 85 ppm groups were greater than those of their respective controls, but were not different from those of other control groups within the same colony. Additionally, no histological changes were noted in testicular tissues of treated animals. The significant increase in testes weights reported in this study was considered to be spurious not likely a direct effect of chloroform exposure (Torkelson et al., 1976).

9.5.8 Butanol and freon 134a Butanol (sec) (CAS # 78-92-2) constitutes up to 20% of Mace formulated by Mace Security International of Bennington VT. Its effects have been recently reviewed by Sullivan et al. (2001). In animals, 2-butanol is absorbed through the lungs and gastrointestinal tract. Approximately 97% of the dose of 2-butanol in animals is converted by alcohol dehydrogenase to the corresponding ketone, which is either excreted in the breath and urine or further metabolized (IPCS, 1987). No teratogenic effects have been observed in pregnant rats up to maternally narcotic (7,000 ppm or 21,546 mg/m3) dose levels. The NOAEL in rats is 3,500 ppm (10,773 mg/m3) when given by inhalation exposure for 7 h per day, based on reduced fetal bodyweight at 5,000 ppm, which was a maternally toxic (narcotic) dose level. The lowest dose was a clear no effect level (Nelson et al., 1989). 2-butanol is reported to be excreted in human breast milk, but no data were presented (Byczkowski et al., 1994). Dymel (Freon) 134a (CAS # 811-97-2; c2h2f4; 1,1,1,2-tetrafluoroethane) is used as a propellant for SABRE DEFENCE sprays manufactured by the Security Equipment


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Corporation of Fenton, MO. It is said to have an extremely low order of toxicity. No exposure-related effects were observed in a standard fertility study in which groups of rats were exposed to 0, 2,500, 10,000, or 50,000 ppm (0, 10,425, 41,700, or 208,500 mg/m3) 1,1,1,2-tetrafluoroethane, 1 h/day during gametogenesis, mating, and post-mating (Alexander et al., 1996). The results from a dominant lethal study revealed no effect on fertility in male rats (Hodge et al., 1979). In a standard developmental toxicity study in rats, delayed fetal development (a statistically significant reduction in mean fetal weight, delayed ossification of digits) was observed when the dams were exposed to 50,000 ppm (208,500 mg/m3) 1,1,1,2-tetrafluoroethane; no significant exposure-related effects were observed at 10,000 ppm (41,700 mg/m3) (Hodge et al., 1980). No other exposure-related developmental effects were observed in rats at levels up to 40,000 ppm (166,800 mg/m3) 1,1,1,2-tetrafluoroethane, a concentration causing decreased maternal body weight gain in rabbits (Wickramaratne, 1989). In the study with rabbits, there was a 30% reduction during exposure with subsequent recovery, resulting in a net reduction in body weight of 3% compared with controls. Dupont has assigned a provisional AEL (Acceptable Exposure Limit) of 1,000 ppm (8-h and 12-h Time-Weighted Average (TWA)) to Dymel 134a. DuPont does not support the use of Dymel 134a as a propellant in high-volume aerosol personal products.

9.6 STRESS AND DEVELOPMENTAL EFFECTS Riot control agents are potent stressors and may, by direct action, cause perturbations in reproductive function, endocrine function, and endocrine gland morphology. Furthermore, RCA-induced alterations in endocrine physiology, in particular that of the adrenals, may indirectly affect reproductive function as the adrenals have an important role in both reproductive function and development. Therefore, in order to fully evaluate the reproductive and developmental effects of RCAs, the role of stress in reproductive function and development must be examined. Major malformations correspond to insults incurred during the first two months of gestation. Thereafter, histological and biochemical abnormalities may result from a variety of negative maternal incidents and can, even without causing obvious malformations, change the phenotype of the conceptus. These abnormalities may then lead to essentially functional disorders compatible with life but ridden with various degrees of handicaps. All systems, when they encounter such an insult at such a stage of development, can be affected. However, the central nervous system (CNS) offers a particularly susceptible system due to its long period of maturation both in utero and after birth. One such example of this susceptibility is the mental retardation documented in children born of mothers who were subjected to atomic radiation, ingested methylmercury from industrial waste, lead, alcohol, and tobacco. Animal experiments confirm these data, adding pathogenic explanations. All of these observations and experiments demonstrate the multifactorial cause of such an abnormality. Toxic substances or drugs can also be responsible for such abnormalities through a genetic attack on spermatogenesis. Behavioral teratogenesis also opens a larger perspective related to the optimal quality of the conceptus and the determining factors, from stress or dietary factors during apparently normal pregnancy to paternal age at the moment of conception. Finally, given that other systems than the CNS can be involved in histological or biochemical abnormalities, such as the reproductive system, we must ask what other types of functional pathology can be induced by interventions on gametes, the embryo, and the fetus. Thus, behavioral teratogenesis leads to the teratogenesis of functions (Auroux, 1997).



9.6.1 Severe stress during pregnancy may cause birth defects Women who are exposed to severe emotional stress during the first trimester of pregnancy are more likely to have children with birth defects, according to new research. Researchers examined the medical records of more than 3,500 women who were exposed before or during pregnancy to extreme stress due to a male partner or older child being diagnosed with cancer, having a heart attack, or dying. They then compared the incidence of birth defects with the incidence in a “control” group of more than 20,000 women who had not been exposed to these events. About 1.18% of pregnancies in women under extreme stress resulted in an infant with a birth defect. About 0.65% of all pregnancies resulted in an infant with such malformations. This corresponds to a greater than 80% increased risk. For women experiencing the death of an older child during early pregnancy the risk increased almost 5-fold and if the death of the older child was unexpected the risk increased more than 8-fold. Because stress affects many of the body’s systems, including the nervous system, cardiovascular system, endocrine system, and immune system, there is good reason to suspect that severe emotional stress could cause defects, especially during the early stages of pregnancy when development is occurring at the fastest rate, researchers explain. Babies born to the severe-stress group of women were more likely to have defects of the cranial nerve crest, a structure of cells that is thought to contribute to the development of the head and face, such as the skull, palate, teeth, nose, parts of the eyes, ears, throat and heart (Hansen et al., 2000).

9.6.2 Stress as a developmental toxin It is accepted in clinical medicine that an adverse psychological state may have pathophysiologic consequences. A study of pregnant women found psychological stress to be associated with elevations in maternal blood pressure, heart rate, cardiac output, and plasma epinephrine and norepinephrine. Animal studies have been both positive and negative but it appears likely that a sufficient degree of stress (e.g. loud jet engine noise) applied for a sufficient length of time (e.g. 6 days in mice) has the potential to adversely affect implantation and embryo viability. Maternal stress has also been associated with an increased incidence of cleft palate. Data in humans is imperfect as it is difficult to precisely measure “stress.” However, some reports suggest that severe anxiety may be associated with preterm birth, low birth weight and a low Apgar. Severe anxiety is also associated with smoking, poor nutrition and low socioeconomic status that are also thought to adversely affect fetal outcome. Whether stress by itself is a developmental hazard in humans is still not known (Scialli, 1988).

9.6.3 Stress as a co-teratogen In CD-1 mice, maternal restraint stress was combined with all-trans-retinoic acid (tRA) given during the restraint period (9:00 a.m. to 9:00 p.m.) to determine in what manner and to what degree teratogenesis might be affected by treatment timing within the stress period and to determine the optimum timing for stress-enhanced production of fetal defects. Eleven groups were treated on gestation day 9 (copulation plug day 1): group 1, vehicle (corn oil) control (C); group 2, food/water deprived (FWD); group 3, restraint only (R); group 4, tRA plus food/water deprivation (tRA FWD); groups 5 and 6, tRA at 0 or 4 hour after 9:00 a.m., that is, tRA(0) and tRA(4), respectively; and groups 7–11, restraint


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plus tRA at 0, 2, 4, 8, or 12 hour after 9:00 a.m. (i.e. R tRA(0), R tRA(2), R tRA(4), R tRA(8), and R tRA(12), respectively). The tRA dose was 20 mg/kg, PO; mice were restrained in the supine position. FWD mice were deprived for the same 12 hour as the restrained mice. All stated differences were significant (P 0.05), based on litter incidences. The incidences of short tails (65%), fused ribs (62%), and fused vertebrae (37%) were elevated in the R tRA(4) group in comparison with all others, and there appeared to be more exencephalies in R tRA(2) litters than in any others. The incidence of supernumerary ribs was elevated in the R group in comparison with C and it was further elevated by tRA at all treatment times (Rasco and Hood, 1995). In another mouse study, researchers examined the effects of stress induced by restraint on individual days during the period of major organogenesis (days 6–14). Weight loss and stress-induced analgesia as assessed by the tail-flick method were used to determine the degree of stress induced by a 12 hour restraint period. Restrained animals lost significantly more weight and had longer tail-flick latencies than the concurrent food and water deprived controls on all gestational days. Significant increases in embryo/fetal mortality were also observed in the offspring of restrained animals. An increased incidence of supernumerary ribs was found in mice restrained on days 7 and 8. Since maternal toxicity induced by chemical teratogens may be accompanied by a general increase in maternal stress, data suggest that such stress may be an etiological factor in teratology bioassays in which dose levels are sufficiently high to induce overt maternal toxicity (Chernoff et al., 1988).

9.6.4 Heat shock protein and its role in maternal stress and teratogenesis The embryonic stress hypothesis of teratogenesis suggests that a proportion of all human congenital defects is due to a failure in essential gene transcription along with translational preemption by the heat shock response (HSR). With this in mind, the potential usefulness of the murine HSR to screen agents suspected of being human teratogens was examined. The teratogenic potential of a selected group of known teratogenic (hyperthermia, insulin, retinoic acid and valproic acid) and non-teratogenic (cycloheximide, dinitrophenol and tetracycline) agents were administered to pregnant SWV mice at critical periods of neural tube closure. Following exposure to either teratogenic doses or at the highest dose possible that did not induce maternal toxicity for those compounds that were not teratogenic, the induction of heat shock protein (HSP) synthesis and changes in total protein synthesis were determined in lymphocytes isolated from murine spleens. The varied results obtained in these studies cast doubt on the value of the murine HSR to screen teratogens (Finnell et al., 1992). Hamster dams dosed continuously with arsenate and exposed to short-term hyperthermia produced a greater percentage of malformed offspring than did hamster dams dosed with arsenate alone. Hamsters receiving both treatments possessed elevated arsenic concentrations in the maternal blood and placentas immediately after cessation of the hyperthermic insult. Blood levels of arsenic were the same as those of animals not receiving the heat treatment within several h post-hyperthermia; however, arsenic concentrations remained elevated in placentas, the duration being dependent on the dose of arsenate. This suggests that the rise in placental arsenic concentrations is the basis of the increase in the production of fetal malformations for hamsters treated continuously with arsenate and heat stressed during critical organogenesis (Hanlon and Ferm, 1986). This also suggests that heat, either directly as a stress or indirectly through a mediator such as HSP, may have some role in increased rate of malformations. Therefore, when considering the reproductive and developmental effects of any possible teratogen, especially



one as suspect as an RCA, it is clear that much needed future studies must take into account not only direct effects of the agent but that of the maternal “stress” inherent to the use of such agents in the real world.

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BATES, H.K., MCKEE, R.H., BIELER, G.S., BARDINER, T.H., GILL, M.W., STROTHER, D.E., and MASTEN, L.W. (1994) Developmental neurotoxicity evaluation of orally administered isopropanol in rats, Fundamental and Applied Toxicology, 22: 152–158. BELL, B.P., FRANKS, P., HILDRETH, N. et al. (1991) Methylene chloride exposure and birth weights in Monroe County, New York, Environmental Research, 55: 31–39. BoRNSCHEIN, R.L., HASTINGS, L., and MANSON, J.M. (1980) Behavioral toxicity in the offspring of rats following maternal exposure to dichloromethane, Toxicology and Applied Pharmacology, 52: 29–37. BOVE, F.J., FULCOMER, M.C., KLOTZ, J.B. et al. (1992a) Population-based surveillance and etiological research of adverse reproductive outcomes and toxic wastes. Report on Phase IV-A: Public drinking water contamination and birth weight, fetal deaths, and birth defects. A cross-sectional study, New Jersey Department of Health. BOVE, F.J., FULCOMER, M.C., KLOTZ, J.B. et al. (1992b) Population-based surveillance and etiologic research of adverse reproductive outcomes and toxic wastes. Report on Phase IV-A: Public drinking water contamination and birth weight, fetal deaths, and birth defects, A case-control study, New Jersey Department of Health. BOVE, F.J., FULCOMER, M.C., KLOTZ, J.B. et al. (1995) Public drinking water contamination and birth outcomes, American Journal of Epidemiology, 141: 850–862. BYCZKOWSKI, J.Z., GEARHART, J.M., and FISHER, J.W. (1994) Occupational exposure of infants to toxic chemicals via breast milk, Nutrition, 10: 43–48. CHERNOFF, N., MILLER, D.B., ROSEN, M.B., and MATTSCHECK, C.L. (1988) Developmental effects of maternal stress in the CD-1 mouse induced by restraint on single days during the period of major organogenesis, Toxicology, 51: 57–65. CLAYTON, G. and CLAYTON, F. (1982) Patty’s Industrial Hygiene and Toxicology. 3rd revised edition. New York, NY: John Wiley & Sons. COATE, W.B., HOBERMAN, A.M., and DURLOO, R.S. (1984) Inhalation teratology study of benzene in rats. In: H.N. MacFarland (ed.), Advances in Modern Environmental Toxicology, vol VI. Applied Toxicology of Petroleum Hydrocarbons. Princeton (NJ): Princeton Scientific Publishers, Inc; pp. 187–198. FALK, A., GULLSTRAND, E., LOUML, F.A., and WIGAEUS-HJELM, E. (1990) Liquid/air partition coefficients of four terpenes, British Journal of Industrial Medicine, 47: 62–64. FALK-FILIPSSON, A., LOUML, F.A., HAGBERG, M., WIGAEUS-HJELM, E., and WANG, Z. (1993) d-Limonene exposure to humans by inhalation: uptake, distribution, elimination, and effects on the pulmonary function, Journal of Toxicology and Environmental Health, 38: 77–88. FINNELL, R.H., AGER, P.L., ENGLEN, M.D., and BENNETT, G.D. (1992) The heat shock response: potential to screen teratogens, Toxicology Letters, 60: 39–52. FRAUNFELDER, F.T. (2000) Is CS gas dangerous? British Medical Journal, 320: 458–459. HANLON, D.P. and FERM, V.H. (1986) Teratogen concentration changes as the basis of the heat stress enhancement of arsenate teratogenesis in hamsters, Teratology, 34: 189–193. HANNA, L.A., PETERS, J.M., WILEY, L.M. et al. (1997) Comparative effects of essential and non-essential metals on pre-implantation mouse embryo development in vitro, Toxicology, 116: 123–131. HANSEN, D., LOU, H.C., and OLSEN, J. (2000) Serious life events and congenital malformations: a national study with complete follow-up, Lancet, 356: 875–880. HARDIN, B.D. and MANSON, J.M. (1980) Absence of dichloromethane teratogenicity with inhalation exposure to rats, Toxicology and Applied Pharmacology, 52: 22–28. HODGE, M., ANDERSON, D., BENNETT, I., and WEIGHT, T. (1979) Arcton 134a: Dominant lethal study in the mouse. Alderley Park, Cheshire, ICI Central Toxicology Laboratory (Report No. CTL/R/437, unpublished). HODGE, M., KILMARTIN, M., RILEY, R., WEIGHT, T., and WILSON, J. (1980) Arcton 134a: Teratogenicity study in the rat, Alderley Park, Cheshire, ICI Central Toxicology Laboratory (Report No. CTL/P/417, unpublished). IGIMI, H., NISHIMURA, M., KODAMA, R., and IDE, H. (1974) Studies on the metabolism of d-limonene (p-mentha-1,8-diene). I. The absorption, distribution and excretion of d-limonene in rats, Xenobiotica, 4: 77–84. 178 © 2004 by CRC Press LLC


IPCS (1987) Environmental Health Criteria 65. Butanols – four isomers. World Health Organization, Geneva. KELLER, K.A. and SNYDER, C.A. (1986) Mice exposed in utero to low concentrations of benzene exhibit enduring changes in colony forming hematopoietic cells, Toxicology, 42: 171–181. KELLER, K.A. and SNYDER, C.A. (1988) Mice exposed in utero to 20 ppm benzene exhibit altered numbers of recognizable hematopoeitic cells up to seven weeks after exposure, Fundamental Applied Toxicology, 10: 224–232. KIRBY, M.L., GALE, T.F., MATTIO, T.G. (1982) Effects of prenatal capsaicin treatment on fetal spontaneous activity, opiate receptor binding, and acid phosphatase in the spinal cord, Experimental Neurology, 76: 298–308. KODAMA, R., OKUBO, A., ARAKI, E., NODA, K., IDE, H., and IKEDA, T. (1977a) Studies on d-limonene as a gallstone solubilizer (VII). Effects on development of mouse fetuses and offspring, ( Japan) Oyo Yakuri, 13: 863–873. KODAMA, R., OKUBO, A., SATO, K., ARAKI, E., NODA, K., IDE, H., and IKEDA, T. (1977b) Studies on d-limonene as a gallstone solubilizer (IX). Effects on development of rabbit fetuses and offspring, ( Japan) Oyo Yakuri, 13: 885–898. KRAMER, M.D., LYNCH, C.G., ISACSON, P. et al. (1992) The association of waterborne chloroform with intrauterine growth retardation, Epidemiology, 3: 407–413. KUNA, R. and KAPP, R.W. (1981) The embryotoxic/teratogenic potential of benzene vapor in rats, Toxicology and Applied Pharmacology, 57: 1–7. LAKAHAI, M.S. (1962a) The effect of chloroacetophenone on chick embryos cultured in vitro, Journal of Embryology and Experimental Morphology, 10: 373–382. LAKAHAI, M.S. (1962b) The effect of chloroacetophenone on the inducing capacity of Henson’s node, Journal of Embryology and Experimental Morphology, 10: 383–388. LAND, P.C., OWEN, E.L., and Linde, H.W. (1979) Mouse sperm morphology following exposure to anesthetics during early spermatogenesis, Anesthesiology, 51: 259. LEE, H.Y. and KALMUS, G.W. (1975) Studies on cell differentiation: inducing capacity of sulfhydrylcontaining amino acids on post-nodal pieces of chick blastoderms, Journal of Experimental Zoology, 193: 37–45. LEHMAN-MCKEEMAN, L.D. and CAUDILL, D. (1992) Biochemical basis for mouse resistance to hyaline droplet nephropathy: lack of relevance of the alpha2 -globulin protein superfamily in this male rat specific syndrome, Toxicology and Applied Pharmacology, 112: 214–221. LUGO, O., CASSADY, G., and PALMISANO, P. (1969) Acute maternal arsenic intoxication with neonatal death, American Journal of Diseases of Children, 117: 328–330. MARTY, M.S., NEEPER-BRADLEY, T.L., NEPTUN, D.A., and CARNEY, E.W. (1999) Developmental toxicity of diethanolamine applied cutaneously to CD rats and New Zealand White rabbits, Regulatory Toxicology Pharmacology, 30: 169–181. MURRAY, F.J., JOHN, J.A., RAMPY, L., KUNA, R.A., and SCHWETZ, B.A. (1979a) Embryotoxicity of inhaled benzene in mice and rabbits, American Industrial Hygiene Association Journal, 40: 993–998. MURRAY, F.J., SCHWETZ, B.A., MCBRIDE, J.B. et al. (1979b) Toxicity of inhaled chloroform in pregnant mice and their offspring, Toxicology and Applied Pharmacology, 50: 515–522. NARASIMHAMURTHY, M. and NARASIMHAMURTHY, K (1988) Non-mutagenicity of capsaicin in albino mice, Food and Chemical Toxicology, 26: 955–958. NELSON, B.K., BRIGHTWELL, W.S., MACKENZIE-TAYLOR, D.R., KHAN, A., BURG, J.R., WEIGEL, W.W., and GOAD, P.T. (1988) Teratogenicity of n-propanol and isopropanol administered at high inhalation concentrations to rats, Food and Chemical Toxicology, 26: 247–254. NELSON, B.K., BRIGHTWELL, W.S., KHAN, A., BURG, J.R., and GOAD, R.T. (1989) Lack of selective developmental toxicity of three butanol isomers administered by inhalation to rats, Fundamental and Applied Toxicology, 12: 469–479. NEWELL, G.W. and DILLEY, J.V. (1978) Teratology and acute toxicology of selected chemical pesticides administered by inhalation, Report by Stanford Research Institute, Menlo Park, CA, to Health


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Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC. NIOSH-RTECS (1999) 1,2 Propanediol RTECS#: TY2000000. National Institute for Occupational Safety and Health. The Registry of Toxic Effects of Chemical Substances. March, 1999 (update). NITSCHKE, K.D., EISENBRANDT, D.L., LOMAX, L.G. et al. (1988) Methylene chloride: two generation inhalation reproductive study in rats, Fundamental and Applied Toxicology, 11: 60–67. NTP (1985) Propylene Glycol (CAS No. 57-55-6): Reproduction and fertility assessment in CD-1 mice when administered in drinking water, Report # RACB84068 P NTIS# PB86140662. NTP (1986) National Toxicology Program – Technical Report Series No. 306, Toxicology and carcinogenesis studies of dichloromethane (methylene chloride) in F344/N rats and B6C3F1 mice (inhalation studies), Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institutes of Health. OLAJOS, E.J. and SALEM, H. (2001) Riot control agents: pharmacology, toxicology, biochemistry and chemistry, Journal of Applied Toxicology, 21: 355–391. PELLICER, F., PICAZO, O., and LEON-OLEA, M. (2001) Effect of red peppers (Capsicum frutescens) intake during gestation on thermonociceptive response of rat offspring, Behavior and Brain Research, 119: 179–183, PELLIZZARI, E.D., HARTWELL, T.D., HARRIS, B.S.H. III, WADELL, R.D., WHITAKER, D.A., and ERICKSON, M.D. (1982) Purgeable organic compounds in mother’s milk, Bulletin Environmental Contamination Toxicology, 28: 322–328. PRUKOP, J.A. and SAVAGE, N.L. (1986) Some effects of multiple, sublethal doses of monosodium methaneargenate (MSMA) herbicide on hematology, growth and reproduction of laboratory mice, Bulletin of Environmental Contamination and Toxicology, 36: 337–341. RAJE, R., BASSO, M., TOLEN, T. et al. (1988) Evaluation of in vivo mutagenicity of low-dose methylene chloride in mice, Journal of the American College of Toxicology, 7: 699–703. RASCO, J.F. and HOOD, R.D. (1995) Enhancement of the teratogenicity of all-trans-retinoic acid by maternal restraint stress in mice as a function of treatment timing, Teratology, 51: 63–70. ROBERTSON, O.H., LOSLI, C.G., and PUCK T.T. (1947) Test for chronic toxicity of propylene glycol and triethylene glycol on monkeys and rats by vapor inhalation and oral administration, Journal of Pharmacology and Experimental Therapeutics, 91: 52–76. ROGERS, E. H., CHERNOFF, N., and KAVLOCK, B.J. (1981) The teratogenic potential of cacodylic acid in the rat and mouse, Drug and chemical Toxicology, 4: 49–61. SCHARDEIN, J.L. (1993) Inhalation developmental toxicity study in rats, IRDC, Mattawan, MI, Project #: 656-007. SCHARDEIN, J.L. (1994) Two generation inhalation reproduction/fertility study in rats, IRDC Mattawan, MI, ID #: 656-011. SCHWETZ, B., LEONG, B., and GEHRING, P. (1974a) Embryo- and fetotoxicity of inhaled chloroform in rats, Toxicology and Applied Pharmacology, 28: 442–451. SCHWETZ, B.A., LEONG, B.K., and GEHRING, P.J. (1974b). Embryo- and fetotoxicity of inhaled carbon tetrachloride, 1,1-dichloroethane and methyl ethyl ketone in rats, Toxicology and Applied Pharmacology, 28: 452–464. SCHWETZ, B.A., LEONG, B.J., and GEHRING, P.J. (1975) The effect of maternally inhaled trichloroethylene, perchloroethane, methyl chloroform, and methylene chloride on embryonal and fetal development in mice and rats, Toxicology and Applied Pharmacology, 32: 84–96. SCIALLI, A.R. (1988) Reproductive Toxicology, 1: 163. SIDELL, F.R. (1997) Riot Control Agents. In: F.R. Sidell, E.T. Takafuji, and D.R. Franz (eds) Medical Aspects of Chemical and Biological Warfare, Washington, DC: TMM Publications, pp. 307–324. SMYTH, H.F., SMYTH, H.F., JR, and CARPENTER, C.P. (1936) The chronic toxicity of carbon tetrachloride: animal exposure and field studies, Journal of Industrial Hygiene and Toxicology, 18: 277–298. SULLIVAN, F.M., BARLOW, S.M., and MCELHATTON, P.R. (2001) A Review of the potential teratogenicity of substances emanating from landfill sites.



TABOCOVA, S., HUNTER, E.S. III, and GLADEN, B.C. (1996) Developmental toxicity of inorganic arsenic in whole embryo: culture oxidation state, dose, time , and gestational age dependence, Toxicology and Applied Pharmacology, 138: 298–301. TATRAI, E., UNGVARY, G.Y., HUDAK, A. et al. (1980) Concentration dependence of the embryotoxic effects of benzene inhalation in CFY rats, Journal of Hygiene, Epidemiology, Microbiology, and Immunology, 24: 363–371. TORKELSON, T.R., OYEN, F., and ROWE, V.K. (1976) The toxicity of chloroform as determined by single and repeated exposure of laboratory animals, American Industrial Hygiene Association Journal, 37: 697–705. TSUJI, M., FUJISAKI, Y., OKUBO, A., ARIKAWA, Y., NODA, K., IDE, H., and IKEDA, T. (1975) Studies on d-limonene, as gallstone solubilizer (V): effects on development of rat fetuses and offspring, (Japan) Oyo Yakuri, 10: 179–186. TYL, R.W., FRANCE, K.A., FISHER, L.C., PRITTS, I.M., TYLER, T.R., PHILLIPS, R.D., and MORAN, E.J. (1987) Developmental toxicity evaluation of inhaled methyl isobutyl ketone in Fischer 344 rats and CD-1 mice, Fundamental and Applied Toxicology, 8: 319–327. TYL, R.W., MASTEN, L.W., MARR, M.C., MYERS, C.B., SLAUTER, R.W., GARDINER, T.H, STROTHER, D.E., MCKEE, R.H., and TYLER, T.R. (1994) Developmental toxicity evaluation of isopropanol by gavage in rats and rabbits, Fundamental and Applied Toxicology, 22: 139–151. UPSHALL, D.G. (1973) Effects of o-chlorobenzylidene malononitrile (CS) and the stress of aerosol inhalation upon rat and rabbit embryonic development, Toxicology and Applied Pharmacology, 24: 45–59. UPSHALL, D.G. (1974) The effects of dibenz[b,f] [1,4]oxazepine (CR) upon rat and rabbit embryonic development, Toxicology Applied Pharmacology, 29: 301–311. WICKRAMARATNE, G. (1989) HFC 134a: teratogenicity inhalation study in the rabbit. Alderley Park, Cheshire, ICI Central Toxicology Laboratory (Report No. CTL/P/2504, unpublished). WLODARCZYK, B.J., BENNETT, G.D., CALVIN, J.A. et al. (1996) Arsenic-induced neural tube defects in mice: alterations in cell cycle gene expression, Reproductive Toxicology, 10: 447–454. YORK, R.G. (1994) Inhalation developmental toxicity study in New Zealand White Rabbits,” (IRDC, Mattawan, MI, Project #: 656-009.


CHAPTER

10

Genetic Toxicity of Riot Control Agents JOYCE M. DURNFORD Battelle Columbus Operations, 505 King Avenue, Columbus, USA

10.1 INTRODUCTION Genotoxic compounds cause heritable genetic change. They may directly damage DNA or they may interfere with the ability of cells to properly segregate their chromosomes during cell division. Genotoxic effects are manifest as DNA fragments, oddly shaped chromosomes, missing chromosomes, induction of DNA repair mechanisms, or mutations leading to gene defects. Sometimes genetic damage can lead to cancer induction. The genotoxicity and carcinogenicity results for the riot control agents (RCAs) addressed in this chapter are summarized in Table 10.1. In this table, a () indicates that most of the studies reviewed show that the compound is positive for this test and a () indicates that most of the studies show the compound negative for the indicated test. Where data are equally divided, both symbols appear. Details are presented later in this chapter in sections focused on each agent. Table 10.1 illustrates an important point. Whether or not something is scored genotoxic may depend on the assay used because the tests reflect different mechanisms of genotoxicity. Until the mechanism of action of a compound is well defined, it is important to utilize a variety of techniques, and it is as important to know why a chemical is not active as to know why it is active in any

TABLE 10.1 Summary of genotoxicity test results Test

Gene mutation in bacteria Gene mutation in animal cells Micronuclei formation Physical damage to DNA Carcinogenicity

Results, by agent CSa

CRb

CNc

Capsaicind

n.d. n.d.

n.d. n.d.

Notes a CS (2-chlorobenzylidene malononitrile). b CR (Dibenz[b,f ]1:4-oxazepine). c CN (1-chloroacetophenone). d Capsaicin is the major active ingredient of oleoresin capsicum. n.d. no data found.


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particular test (McGregor et al., 1988). As McGregor stresses, “No in vitro test can, by itself, tell us if a chemical is or is not a carcinogen” (McGregor et al., 1988). Because the testing methods are important to interpretation of the results, the tests are briefly described first, and then the results for each agent are reviewed.

10.2 GENOTOXICITY TESTS 10.2.1 Bacterial mutation Bacterial mutation assays are firmly established for screening chemicals and environmental samples for genotoxicity. In fact, the Ames assay, a bacterial mutation assay, is the most widely used test for primary screening (Venitt et al., 1984; Meshram et al., 1992). The results of bacterial mutation assays correlate well (78–90%) with the results obtained with carcinogenicity tests in rodents (reviewed by Meshram et al., 1992). The Ames test (Ames et al., 1975), measures mutation in genes necessary for histidine biosynthesis. Several strains of Salmonella typhimurium are used, each carrying a different mutation. The strains have been further modified to have increased cell wall permeability (making it more probable that the test compound will get inside the bacteria), and most are defective in DNA repair (which enhances the probability of detecting gene mutation). To conduct the test, the bacteria are exposed to test chemical and then are cultured under conditions where only mutants will be able to grow. Because large populations of bacteria can be exposed to test agent (over 2 108 bacteria per plate), very rare events can be detected and these assays are very sensitive. Two factors must be considered in conducting bacterial mutation assays: (1) is the compound toxic? and (2) is the compound metabolized by animals into a genotoxic form? Let’s consider toxicity first. If a compound kills cells at the dose tested, the killed cells may release enough nutrients to permit nonmutant cells to grow, particularly in assays incubated extended times (Wild et al., 1983; Meshram et al., 1992). Thus, failure to account for toxic compounds can lead to false positive results in mutation assays. Similarly, failure to consider metabolic activation can lead to false negatives. The mammalian liver contains oxidative enzyme systems to metabolize foreign chemicals. Usually this inactivates the chemical and prepares it for excretion. Sometimes an inactive chemical is metabolized into electrophilic metabolite(s) that can interact with DNA. In these cases, although the parent compound itself may not be genotoxic, it is metabolized to a form that is. This is called metabolic activation. In assay systems like bacteria and isolated animal cells, one must artificially provide this metabolic activation function by adding an enzyme mix called S9 derived from mammalian livers.

10.2.2 Mammalian cell mutation Animal cells are more complex than are bacterial cells. They have an organized nucleus, structured chromosomes, and apparatus for chromosomal segregation during cell division. Mutagenesis assays conducted in mammalian cells can give information about the genotoxicity of compounds that act on these more complex structures. Such information cannot be obtained with bacteria, which lack both nucleus and multiple chromosomes. The general approach to study mutation in mammalian cells is similar to the approach to study mutation in bacterial cells. A large population of animal cells in culture is exposed to test substance. Since these are isolated cells, one must test with and without the addition of S9 to provide metabolic activation, and one must control for toxicity of the test


GENETIC TOXICITY OF RCA

compound. After exposure, the treated cells are then cultured without selection to deplete nonmutant enzyme that might have been in the parent cell and to permit the segregation of DNA into daughter cells. Since mammalian cells have two copies of each chromosome, and since only one copy may carry the mutation, it is important that the cells go through at least one cell division before selection for mutants. This culture time, called the expression time, varies with cell type. After the expression period, the cells are placed under culture conditions where only mutants are able to grow. Control cultures are incubated under conditions where all the cells can grow. Mutation frequency is the ratio of the number of cells grown on selective media (mutants only) to the total number of viable cells grown on nonselective media (Cole and Arlett, 1984). Two mammalian mutation systems are commonly used, both based on mutations in enzymes which render cells resistant to toxic drugs. The enzyme, hypoxanthine–guanine phosphoribosyltransferase (HGPRT) is a salvage enzyme that normally recycles byproducts of nucleic acid synthesis. Mutations in this enzyme renders cells resistant to 6-Thioguanidine (6-TG) and 8-Azaguanine (8-AG). Tests can be done in L5178Y mouse lymphoma cells, in V79 cells and in Chinese Hamster Ovary (CHO) cells. Mutations in the enzyme thymidine kinase render cells resistant to 5-Bromodeoxyuridine (5 BrdUrd) and Trifluorothymidine (TFT). This test can be conducted in the L5178Y TK (/) mouse lymphoma cell line.

10.2.3 DNA damage Physical damage to DNA sometimes is detected directly. Three kinds of assays are used: DNA fragmentation, chromosomal aberration, and sister chromatid exchange. DNA fragments can be detected by electrophoresis, an analytic technique that separates molecules by size. Small molecules migrate more rapidly through a semisolid gel under the influence of an electric field than do large molecules. DNA can be first purified from cells and then analyzed (Richeaux et al., 2000), or individual cells can be lysed directly in the electrophoretic system (Richeaux et al., 2000) and the electrophoretic mobility pattern of the entire DNA from one cell can be studied. Damaged DNA, which is smaller, migrates faster forming a pattern that resembles a comet tail when the DNA is stained. This “comet assay” is “the only currently available method with sufficient sensitivity to detect initial DNA damage in individual cells and possible repair of that damage” (Richeaux et al., 1999). Chromosomal damage can be detected by microscopic examination of stained smears of metaphase chromosomes collected from cells. Each chromosome has an expected size, length of arm, and position of the centromere. Variations in any of these are chromosomal aberrations. In the sister chromatid exchange assay, cells are incubated during one cell cycle with chemicals to specifically label one strand of DNA. The cells are then exposed to test chemical. If the chemical causes a break in one strand of DNA and if the broken DNA is then transferred from one strand to another, one can detect the exchange by microscopic examination of the stained chromosomes.

10.2.4 Micronuclei formation Micronuclei result when the chromosomal material is not properly distributed during cell division. If DNA is not properly distributed to spindles, it may end up in only one of the daughter cells, and may form one or more small nuclei called micronuclei. These small nuclei are identified by microscopic examination of the cells after treatment. Micronuclei are mostly composed of either acentric fragments of DNA or of lagging chromosomes resulting from spindle disturbances. They can occur in any proliferating tissue. Since red blood cells (erythrocytes) lack nuclei, micronuclei are easy to see, and these cells are often


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chosen for examination in tests of micronuclei (described by Adler, 1984). Spindle disturbances lead to the formation of micronuclei and to chromosome loss, which may be detected in mutagenicity assays. The National Toxicology Program (NTP) of the United State has begun rigorous program to test by the micronucleus assay chemicals that have been tested in the Salmonella mutagenicity assay as well in the rodent carcinogenicity assay. The in vivo bone marrow micronucleus assay is used to identify chemical carcinogens that act by genotoxic mechanism (Yang et al., 1992).

10.2.5 DNA repair All cells have mechanisms to recognize DNA damage, excise the damaged sequences and replace the damaged DNA with newly synthesized (or repaired) DNA. This repair synthesis is not done during cell division, and is performed by different enzymes than those responsible for cell replication. If DNA repair is induced, one can infer that DNA damage must have occurred. One can detect the induction of DNA repair synthesis by incubating nonreplicating cells in the presence of DNA precursors that can be monitored (e.g. precursors that are radioactive, have an altered density, or are fluorescent). One example of such an analysis is the BrdUrd density shift method (Pettijohn and Hanawalt, 1964), in which repair synthesis leads to the incorporation of radioactivity into the parental strands of DNA.

10.2.6 Whole animal assays Neither bacterial cells nor cultured mammalian cell cultures, even with the addition of liver enzyme extracts, can mimic all aspects of animal exposure to a test chemical. Some compounds that are mutagenic in vitro (i.e. in the Salmonella/Ames assay) are not carcinogenic in rodents because the compound may not be able to reach target organ, it may be labile, or it may not be metabolized properly in vitro (Yang et al., 1992). In a whole animal, one can deliver the test chemical by any route of exposure (e.g. aerosol, skin paint, in food) and study the extent to which the test chemical is absorbed into the body, metabolized, transported to target organs and excreted. The basic procedure is to treat animals by various routes of exposure, then, after an appropriate interval, sample tissue for further analyses, for example, by a cytogenetic examination of metaphase chromosomes or by examining for the presence of micronuclei. In an in vivo test the test material is delivered in some solvent, and controls containing only solvent must be included in the test design. Water and physiologic saline are preferred solvents for compounds soluble in aqueous media. For water-insoluble compounds, vegetable oil, dimethylsulfoxide (DMSO), or diluted ethanol are often used. The concentration of material to be tested is critical. Generally, the maximum dose tested is that which is lethal to half of the test animals (LD50). Sometimes the MTD (maximum tolerated dose) is used. Nontoxic chemicals are tested at the limit of solubility. Generally, two lower doses are also chosen, which are one-half and one-quarter of the maximum dose. In the case of RCAs, which are not very toxic, these high doses may bear little relationship to actual exposure.

10.3 TEST RESULTS BY AGENT Now that the basic tests have been briefly introduced, let us turn to the testing of each of the four RCAs to be studied in this chapter. Not every agent has been tested by every test.



10.3.1 Genotoxicity of CS (2-chlorobenzylidene malononitrile) CS is a potent irritant at very low doses and has a very high margin of safety. Minimal irritant concentrations range from 0.1 to 1.0 mg/m3, and most people find exposure for 10 m to a dose of 1 mg/m3 intolerable (Olajos and Salem, 2001). The dose required to incapacitate 50% of exposed people (the ICt50 5–10 mg-min/m3) is much less than the calculated lethal exposure for humans ( 1 h exposure to 1,000 mg/m3). In animals, acute toxicity is observed at dose much higher than the minimum concentrations causing irritation in humans. In rodents, the LCt50 for inhaled aerosol is 50,000–90,000 mg-min/m3 Ballantyne, 1977; Marrs et al., 1983). CS has been extensively tested (Tables 10.2 and 10.3), and its molecular mechanism of action is reasonably understood.

CS binds proteins When 14C-labeled CS was administered to rats intraperitoneally, radioactivity was found associated with the proteins of liver and kidney, but not with the DNA (Von Daniken et al., 1981). Because less than 100 times as much CS was associated with DNA as with protein, the authors conclude that CS does not bind directly to DNA and does not cause direct DNA damage. It does not stimulate DNA repair in V79 cells, in 3T3 human fibroblasts, or in A549 alveolar tumor cells (Ziegler-Skylakakis et al., 1989). CS forms a covalent interaction with thiols or amino groups on proteins. A dose-dependent increase in spindle disturbances was observed after a 3-h exposure of cultured V79 cells, starting at a dose of 4.7 M CS, the lowest dose tested (Schmid et al., 1989). Because spindle damage can lead to chromosome loss, with associated serious effects, these authors recommend, “CS should be considered a potentially hazardous agent”. In a follow-up study by the same group, CS and its metabolites o-chlorobenzaldehyde and malononitrile were tested on V79 cells. When the exposure time was increased to 20 h, or two cell cycles, a significant increase (19.6% vs 8% in untreated controls) was observed in the number of aneuploid cells after exposure to CS and o-chlorobenzaldehyde, but not malononitrile (Schmid and Bauchinger, 1991). This is consistent with the hypothesis that the damage to spindles is manifest only after cells have attempted to divide. Disruption in the mitotic spindle can lead to the formation of micronuclei. In V79 cells, a concentration-dependent effect in micronucleus formation was observed, but

TABLE 10.2 CS test concentrations Parameter

Dose

Citation

Noncarcinogenic Maximum tolerated dose Oral LD50 Chromosome loss Spindle disruption Mutagenic to V79 cell Nonmutagenic to Salmonella

170 mg/kg/day (rat) 339 mg/kg/day (mouse) 282 mg/kg (mouse) 37 M, 20 h 4.7 M, 3 h 75 M, 3h Up to 800 g/plate

Ashby and Tennant, 1988 Wild et al., 1983 Schmid and Bauchinger, 1991 Schmid et al., 1989 Ziegler-Skylakakis et al., 1989 Meshram et al., 1992


188

TABLE 10.3 CS genotoxicity results Test

Result

Notes

Citation

Bacterial mutagenesis (Salmonella)

Weak () () ()

Only at 2,000 g/plate Only with TA100 strain; 72-h incubation

von Daniken et al., 1981

() Mutagenicity in V79 Chinese Hamster Cells Sex-linked mutation in fruit flies Mouse micronucleus

() () () () () ()

Stimulate DNA repair Protein akylation Interact with spindle Chromosome loss Chromosomal aberration Sister chromatid exchange Mouse lymphoma forward mutation assay


() () () () () ()

Toxicity noted at 1.5 mg/plate; incubated for 48 h for revertants 5 tester strains; 3 levels S9; criteria for positive response standardized 2-fold increase over solvent controls; tested up to 5–800 g/plate; 200 g/plate toxic 3-h exposure up to 75 M; 6-TG reversion was 4–5 times higher than matched solvent controls

0.3% mutation frequency after 3-day feeding with up to 5 104 M CS 3-h exposure Oral (LD50 282 mg/kg) I.P. (up to 37.8 mg/kg, 3/4 of the LD50) after 30 or 48 h 10 M lowest dose tested had 2 times the frequency of solvent controls; hydrolysis products were negative Rats Cultured V79 cells Cultured V79 cells Cultured V79 cells Cultured V79 cells Weakly positive at 2 g/mL after 4-h exposure

Rietveld et al., 1983 Wild et al., 1983 Meshram et al., 1992 Ziegler-Skylakakis et al., 1989 Wild et al., 1983 Ziegler-Skylakakis et al., 1989 Grawe et al., 1997 Wild et al., 1983 Ziegler-Skylakakis et al., 1989 Ziegler-Skylakakis et al., 1989 von Daniken et al., 1981 Schmid et al., 1989 Schmid and Bauchinger,1991 Bauchinger and Schmid, 1992 Bauchinger and Schmid, 1992 McGregor et al., 1988


even at the lowest dose tested, 19 M CS, micronuclei were twice as frequent as in solvent treated controls (Ziegler-Skylakakis et al., 1989). Other laboratories have repeated this observation, leading to the conclusion that CS is an in vitro aneugen (Salassidis et al., 1991; Nusse et al., 1992; Miller and Nusse, 1993). This may not be true in whole animals, however. At least two in vivo tests have failed to detect micronuclei formation in mice (Wild et al., 1983; Grawe et al., 1997). Mice were given CS by oral or i.p. route at doses approaching the LD50 and were sacrificed after 30 or 48 h treatment. No micronuclei were detected (Wild et al., 1983). The apparent difference in results between the studies with whole mice and the cultured cells remain to be clarified. It seems probable to this author that either the in vivo concentration was not high enough or not present long enough to cause formation of detectable micronuclei in the cells examined. These data stress the importance of confirming in vitro observations with in vivo analyses.

CS mutagenicity to mammalian cells As noted in the previous section, CS can disrupt the mitotic spindle of cultured cells. This spindle disruption can lead to improper chromosome segregation during cell division. Thus, under exposure times and concentrations where spindle disruption is observed, one would expect to see evidence of mutation, and this is the case. Cultured V79 CHO cells exposed for 3 h to 75 M CS showed 4–5 times more revertants to 6-TG resistance than matched solvent controls (Ziegler-Skylakakis et al., 1989). CS was weakly mutagenic at 2.5 g/mL in 2 of 2 tests in the mouse lymphoma forward mutation assay (L5178 tk/tk) with or without the addition of S9 (McGregor et al., 1988). In this experiment, the cultured cells were exposed to chemical for 4 h, and then cultured 2 days before plating in agar with or without selective agent Trifluorothymidine (TFT). Dose-dependent chromosomal damage in the form of chromosomal aberrations and sister chromatid exchange followed in vitro exposure of V79 Chinese hamster cells to CS. The extent of damage was greater when cells were exposed to the CS for 20 h followed by a 20-h recovery period in the absence of CS than when cells were exposed for only 3 h (Bauchinger and Schmid, 1992). Finding chromosomal damage provided the cells underwent one or two cell cycles is consistent with the hypothesis that the primary effect of CS is disruption of the mitotic spindle by binding to cellular protein.

CS and bacterial mutagenesis Since bacteria lack a cell nucleus and the mitotic apparatus found in mammalian cells, and since CS seems to exert its effect by disrupting the mitotic apparatus, it is perhaps not surprising that CS is not mutagenic for S. typhimurium when assayed either in the presence or absence of metabolic activation provided by the S9 microsomal fraction (Rietveld et al, 1983; Wild et al., 1983; Zeiger et al., 1987; Meshram et al., 1992). One report showed CS was weakly mutagenic for Salmonella (Von Daniken et al., 1981), but only with the TA100 strain of Salmonella and only at (very high) doses of 2 mg/plate and only after a (very long) 72-h incubation period. Wild et al., 1983 reported that CS is cytotoxic at 1.5 mg/plate and not mutagenic after a 48-h incubation period. It seems probable that the weakly mutagenic response observed by Von Daniken et al. was a reflection of toxicity. The large number of dead cells on the plates may have, during the long incubation period, provided histidine to cross-feed residual mutant cells, permitting them to form colonies even though they were not revertants (Wild et al., 1983; Meshram et al., 1992). CS is metabolized to ortho-chlorobenzaldehyde and malononitrile, neither of which is mutagenic in Salmonella.


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The mutagenic potential of CS and CS2, a formulation containing CS in a mixture of micro-pulverized CS in an aerogel of 5% Cab-o-Sil® and 1% methyldisilizane, was negative when tested in S. typhimurium strains TA98, TA1535, and TA1537 with or without metabolic activation NTP (1990b).

CS carcinogenicity Carcinogenicity studies were conducted in rats (F2344/N) and mice (B6C3Fl) (NTP, 1990b). Animals were exposed via inhalation over their lifetime to CS2 aerosol. No cancer was observed. Compound-related non-neoplastic lesions characterized as hyperplasia and squamous metaplasia of the respiratory epithelium and degenerative changes of the olfactory epithelium were evident in CS2 exposed rats. Hyperplasia and squamous metaplasia of the respiratory epithelium were also noted in mice exposed to CS2. These findings are not unexpected since the epithelium of transitional areas of the respiratory tract are reported to be the most sensitive areas for cellular alterations such as epithelial degeneration, hyperplasia, and squamous metaplasia following exposure to irritants (Gopinath et al., l987; Burger et al., l989). Neoplastic effects were not observed in either rats or mice exposed to test article leading to the conclusion that CS2 is noncarcinogenic for rats and mice. Similarly, CS was noncarcinogenic in a repeated dose inhalation study (Marrs et al., 1983b) of CS in 300 mice, 200 rats, and 300 guinea pigs exposed 1 h/day for 120 days. Three exposure levels were used (0, 3, 30, and 300 g/L). The highest exposure dose was selected on the basis of pilot studies that produced chronic toxicity, and the lowest doses were selected to approximate the human LD50. The high dose was toxic, and lead to high mortality. The rest of the dose groups were not toxic. Animals were held for 1 year after the last exposure and then sacrificed. There was little mortality compared to controls in animals treated with 30 g/L in all three species. Inflammatory changes were noted in the lungs from all groups of animals. No dose-dependent changes were identified. The authors conclude that at 30 g/L (a dose that is a little over 8 times the dose most humans would find intolerable) given 1 h/day for 120 days caused no adverse effects in any of these species of animal (Marrs et al., 1983b).

10.3.2 Genotoxicity of CN (1-chloroacetophenone) Mutagenicity data on CN is lacking; however, it has been tested for carcinogenicity in rats and mice (Ashby and Tennant, 1988; NTP, 1990a). There was no indication of carcinogenic activity of CN in male rats exposed to test article. Equivocal evidence of carcinogenicity of CN was based on findings in female rats indicating an increase in fibroadenomas of the mammary gland. The findings of a two-year inhalation bioassay in mice, suggested no carcinogenic activity in male or female mice exposed to CN. Composite results from the NTP studies were included in a 1993 computer modeling study (Rosenkranz and Klopman, 1993). Table II of that report lists CN as nonmutagenic by Ames assay and noncarcinogenic for mice, but have equivocal carcinogenicity for rats (i.e. the authors felt that the tests were properly and adequately conducted, but equivocal evidence for carcinogenicity was obtained) (Ashby and Tennant, 1988). The maximum tolerated dose was 0.9 mmole/kg/day for rat and 1.8 mmole/kg/day for mouse.

10.3.3 Genotoxicity of CR (Dibenz[b,f]1:4-oxazepine) CR is a sensory irritant that is more potent than CS or CN and less acutely toxic than CS (Marrs et al., 1982). Pure aerosol of distilled and recrystallized CR has such low toxicity when inhaled, that an LCt50 cannot be calculated (Ballantyne 1977 cited by Marrs et al.,



1982, 1983a). No mutagenic or carcinogenic activity was reported in the citations examined for this review. Lab animals seem insensitive to the irritant effect, and disregard concentrations intolerable to humans (Marrs et al., 1983a). There is a paucity of data addressing the subject of genotoxic potential of CR. Colgrave et al. (1983) evaluated the mutagenic potential of CR and its precursor (2-aminodiphenyl ether) in the Salmonella/ Ames assay for bacterial mutagenesis and in mammalian genotoxicity bioassays using Chinese hamster cell mutagenesis (V79/HGPRT system); mouse lymphoma cell mutagenesis (L5178Y/TK/TK); and the micronucleus test (erythrocytes). CR and its precursor were negative in all assays, but the paper provided almost no experimental details. In the same study, golden hamsters and mice were exposed 5 days a week for 18 weeks to aerosolized technical grade CR at 4,223, 2,031, 1,022 mg-min/m3. One year after the start of exposure, survivors were killed. The authors observed increased mortality in high dose animals, but few histological changes. They concluded that CR was not carcinogenic. In a mouse dermal exposure study, mouse skin was painted daily for 12 weeks with 20 L of 50 g/L solution in acetone (1 mg/dose). No skin lesions were observed. After 80 weeks postexposure, animals were sacrificed and examined histologically. No organ toxicity was noted (Marrs et al., 1982). A repeated dose inhalation toxicity to mice and hamsters using technical grade CR exposed animals 5 day/week for 18 weeks. The animals were retained for 1 year after the last exposure. There was a drop in survival at high doses, but no single case of death and no organ specific toxicity (Marrs et al., 1983a). These data suggest that CR probably does not pose a mutagenic threat.

10.3.4 Genotoxicity of capsaicin (8-methyl-N-vanillyl-6-nonenamide) Capsaicin is the major pungent ingredient of hot peppers of the genus Capsicum (Arceo et al., 1995). Capsaicin is detectable at approximately 10 ppm (Arceo et al., 1995). The level of active capsaicin in hot peppers can range from 0.1% to 1% (Surh et al., 1998) reaching 1.82 mg/g in dried fruits (Arceo et al., 1995). The average daily exposure may reach ~0.2 mg/kg in rural Mexican populations (Lopez-Carillo et al., 1994), and has been estimated as high as 50 mg/day in certain Korean populations ( Jang et al., 1991). Human populations who routinely use peppers in their diet, exhibit an increased incidence of gastric cancer (Tajima and Tominaga, 1985; Lopez-Carrillo et al., 1994; Lee et al., 1995). The genotoxicity of capsaicin was reviewed by Azizan and Blevins (1995). Capsaicin has a dual role, acting both to promote and to prevent carcinogenesis and mutagenesis, with substantial anti-genotoxic and anti-carcinogenic effects (reviewed by Surh et al., 1998). When aerosolized, as in pepper spray, capsaicin affects the eyes, airways and skin, causing burning, irritation, tearing, and pain immediately upon exposure. Because of this selective effect on defined subpopulations of sensory neurons, capsaicin has been used as a research tool to study pain mechanisms (Surh and Lee, 1995). In skin exposure studies, it has been found that although capsaicin is very irritating upon first exposure, repeated exposure to the skin makes people less sensitive to pain. The topical application of capsaicin is thought to deplete substance P from local sensory nerve terminals, suppressing the local P-mediated flare response in skin. It inhibits platelet aggregation and interferes with phospholipase A2. These analgesic and anti-inflammatory effects have led to the use of capsaicin as a therapeutic to treat pain. It is the active ingredient in over-the-counter analgesic creams (Zostrix® and Axain®) used to treat arthritis. The concentration of capsaicin is 75 mg/100 mL in Zostrix HP® and 25 g/mL in Zostrix® (Richeaux et al., 2000).Twenty-four h after a single topical application of the Zostrix preparation, 3.75 mg


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will be distributed to the blood, leading to blood levels of 10–20 M (Richeaux et al., 1999).

Mechanisms of action Capsaicin binds the vanilloid receptor, a nonselective cation channel found on neuronal cells and on some non-neuronal cells (mast cells and glial cells) (Caterina et al., 1997; Richeaux et al., 1999). Rat astrocytes (IC50 97 M) and neuroblastoma cells (IC50 60 M) express the vanilloid receptor and are sensitive to capsaicin. DNA fragmentation and strand breaks were detected by the comet assay in cultured neuroblastoma cells (SHSY-5Y) exposed to 50 M capsaicin (Richeaux et al., 1999). Cells without the vanilloid receptor, like endothelial cells, have lower sensitivity to capsaicin. In the endothelial cell (IC50 175 M), capsaicin stimulates lipoperoxidation and the release of soluble intercellular adhesion molecule (sICAM-1), an inflammatory mediator. Capsaicin does not cause DNA fragmentation in these cells (Richeaux et al., 2000). The authors suggest that “capsaicin induces an inflammation process associated with lipid peroxidation, which induces cell death probably involving inhibition of protein synthesis and necrosis … not programmed cell death or any other process involving DNA strand breakage and fragmentation.” To summarize, Richeaux and coworkers have demonstrated that capsaicin causes DNA fragmentation in cells with the vanilloid receptor and not in cells without this receptor.

Metabolism and activation Liver enzymes are very important in metabolizing foreign chemicals. As noted previously, some chemicals are metabolically activated by the liver from innocuous forms to forms that are carcinogenic. The story with capsaicin is a beautiful example of the complex interplay of activation and inactivation that characterizes the sophisticated feedback mechanisms operational in cells. Capsaicin is itself metabolized by the microsomal cytochrome P450-dependent monooxygenases of the liver to a phenoxy radical intermediate that can bind to protein and nucleic acid. This activated metabolite can lead to toxicity, mutagenesis, and carcinogenesis. At the same time, capsaicin and dihydrocapsaicin (trans-8-methyl-N-vanillyl-6-nonanamide) inactivate cytochrome P450 IIE1 and other microsomal monooxygenases by irreversibly binding to the enzymes. This inactivation can have chemoprotective effects against other chemicals that require metabolic activation (reviewed by Surh and Lee, 1995).

Carcinogenicity, cocarcinogenicity and anticarcinogenic activity By this action, capsaicin attenuates carcinogenicity of benzo[a]pyrene and other heterocyclic amines. It inhibits metabolism and covalent DNA binding of aflatoxin B, and modulates expression of c-erb and c-myc, two genes frequently activated in cancer, in livers of mice. Topical application of 0.42 mM capsaicin prior to addition of vinyl carbamate (VC) or N-nitrosodimethylamine (NMDA) inhibited formation of skin tumors in mice. Both VC and NMDA require metabolic activation for the carcinogenic effect, an activation blocked by capsaicin (Surh et al., 1995). A cocarcinogenesis model in rat showed that capsaicin inhibited liver and lung carcinogensis induced by diethylnitrosamine (DEN), N-methylnitrosourea (MNU), N-dibutylnitrosamine (DBN). Alone it did not cause cancers (Jang et al., 1991). The effect of capsaicin on 12-O-tetradecanoylphorbol-13-acetate (TPA), widely used in tumor promotion studies, was studied by LaHann (1986) and Sasajimi et al. (1987). LaHann (1986) concluded that capsaicin appeared to facilitate the onset of TPA-induced tumor formation, and that capsaicin could enhance the risk of skin cancer. Studies by



Sasajimi and coworkers (1987), demonstrated that capsaicin induced ornithine decarboxylase (ODC) activity, an enzyme used as an index of tumor promoting capability. Studies by Kim et al. (1985) suggest that capsaicinoids may act as cocarcinogens. Thus, capsaicin can promote tumor formation in some systems and inhibit it in others. Capsaicin alone was reported in early studies to induce mucous fibrosis in the oral cavity (Sirsat and Khanolkar, 1962; Pindborg et al., 1967). This finding appears not to have been repeated in more recent studies with more pure preparations. In the tumor promotion study of Jang et al., capsaicin alone did not cause cancer (Jang et al., 1991). A dosed feed study with a mixture of capsaicinoids (64.5% capsaicin and 3.26% dihydrocapsaicin) in B6C3F1 mice showed no carcinogenicity in a 79-week study. The tumor incidence (hepatocellular) was negatively correlated with capsaicin dose in both sexes, and the number of tumors in females treated with highest dose was significantly less than control. All other tumors were similar between treated and control groups (Akagi et al., 1998).

Genotoxicity The mutagenic potential of capsaicinoids has been studied in both microbial and mammalian genotoxicity assays. The literature on mutagenicity of capsaicin is contradictory, largely due to variability in the purity of the capsaicin studied (Table 10.4). Since capsaicin is found in foods, many studies have been designed to assess the risk of consuming high concentrations of capsaicin in the diet. Capsaicin extracted from fruits was either negative or weakly positive in the Salmonella mutagenicity assays, and then often only on one test strain of Salmonella or with a particular regimen of S9 activation. Pepper extracts contain a number of components. Some, like carotene, vitamin C and thiamine inhibit mutation (Villasenor and de Ocampo, 1994). Unknown components present in acetone extracts of C. annum peppers inhibited mutagenicity of compounds present in ether extracts from the same fruit (Azizan and Belvins, 1995). Natural capsaicin is a mixture of five kinds of vanillylamides that are hard to separate. The components are capsaicin (63–77%), 6,7 dihydrocapsaicin (21–32%) nordihydrocapsaicin (0.8–9%), homocapsaicin (1%) and homodihydrocapsaicin (3%) (Villasenor et al., 1993). Seven homologs were isolated by HPLC, characterized by mass spectroscopy, then chemically synthesized (Gannett et al., 1988). These authors found that the dominant forms of capsaicin, which they called 1b and 2b, were not mutagenic in the Ames assay with or without the addition of S9 activation, nor was the extract from the peppers. In a mammalian V79 mutagenicity assay, compounds 1b and 2b were mutagenic, but the extract was more so. The authors conclude “the mutagenicity of the red pepper extracts is only partially caused by the capsaicinoids present.” The studies with purified capsaicin suggest that it is not mutagenic for bacteria. It may be mutagenic for mammalian cells.

Micronucleus Natural capsaicin was fractionated from C. frutescens fruits from a local market. At the maximum tolerated dose (1.22 mg/kg) no micronuclei were detected in the mouse erythrocyte micronucleus assay (Villasenor et al., 1993). A year later the same laboratory reported that the fractions identified as C1 and C2 (which contained spectral properties comparable for natural capsaicin) caused micronuclei formation in the mouse bone marrow micronucleus assay (Villasenor and de Ocampo, 1994). Purified capsaicin was positive for micronucleus induction (Nagabhushan and Bhide, 1985; Arceo et al., 1995). It appears from these studies that purified capsaicin probably causes micronuclei formation.


194

TABLE 10.4 Capsaisin genotoxicity results Test

Result

Notes

Citation

Salmonella mutagenesis

()

Chili pepper oleoresin and capsaicinoids studied. Negative against strains TA97, TA100, and TA102; toxic to TA97 and TA98 at 1 mg/plate; Mutagentic for TA98 at 0.75 mg/plate with rat liver S9 but not with mouse liver S9. Oleoresins of Capsicum annuum and Capsicum frutescens were prepared by ethanol extraction from pepper. Streptomycin-dependent derivatives of Salmonella typhimurium TA100 and TA98 were used. Test concentration and toxicity not reported. Tested near ID50. Tested 100, 300, and 1,000 g/plate against strains TA98 and TA 1535 S. typhimurium. These authors chemically synthesized the two main capsaicin components (1b, 2b) of pepper and also tested the pepper extract. Toxicity not reported. Capsaicin was obtained from fresh Capsicum annum (green pepper) using an ether extraction. Weak mutagenesis was observed at 20–40 g per plate, but only on test strain TA100, not on TA97 or TA98. Other components in the extract (e.g. chlorophyll) inhibited the mutagenicity. Popular Thai spices purchased from a local market in Bankok; tested untreated, treated by macerating in water or by boiling in water; sample was applied to a 15 mm disk placed on a streak of Bacillus indicator.

Buchanan et al., 1981

() Low level with S9 but only on one strain and only with rat S9 () without S9

() with S9 () with or without S9

() weak

B. subtilis mutagensis

()

Mammalian cell mutagenesis (V79)

() ()


Red pepper extracts separated and characterized by HPLC and GC-MS. Tested two chemically synthesized components (1b, 2b) and the pepper extract. At 10 g/mL, fraction 1b, 2b,

Toth et al., 1984

Damhoeri et al., 1985

Nagabushan and Bhide, 1985 Gannett et al., 1988

Azizan and Blevins, 1995

Ungsurungsie et al., 1982

Nagabushan and Bhide, 1985 Gannet et al., 1988

() with activation by hamster hepatocytes Enzyme activation in mammalian cell cultures

()

DNA fragmentation in cultured cells

()

()

Mouse Micronucleus

() ()

() ()


and the pepper extract were mutagenic. The mutagenicity in the extract is only partially caused by the capsaicinoids. Crude mixture of capsaicinoids from Capsicum frutescens and synthetic capsaicin and dihydrocapsaicin were mutagenic. Doses tested were from 1 to 50 g/mL. The LD50 is approximately 5–10 g/mL. IC50 for these cultured esophageal epithelial cells was 40 M. Capsaicin at 100 M induced ornithine decarboxylase activity 220% and induced plasminogen activator activity; OCD and PA activation is consistent with tumor promoting activity like that of TPA. Cultured neuroblastoma cells; these cells have the vanilloid receptor, and are killed with an IC50 of 60 M in culture; At 50 M capsaisin, DNA strand break was detected by comet assay. Cultured endothelial cells; these cells do not have the vanilloid receptor. They are killed with an IC50 of 175 M by a mechanism that involved inhibition of protein synthesis; no DNA fragmentation detected by comet assay after exposure of up to 175 M capsaisin. 7.5 mg/kg in mice. Isolated natural capsaicin from Capsicum frutescens. At the maximum tolerated dose of 1.22 mg/kg in mice, given 30 h and 6 h prior to sacrifice. No micronuclei in erythrocytes. Fractionated C. frutescens. At MTD of 1.22 mg/kg saw micronuclei in bone marrow micronucleus assay. Subchronic repeated dose study in mice. Purified capsaicin (1.9 mg/kg i.p. three consecutive days, followed by one-day rest, then repeated for 32 days). Maximum dose 90% higher than expected human exposure. Elevated micronucleus in erythtocytes and SCE.

Lawson and Gannet, 1989

Sasajimi et al., 1987

Richeaux et al., 1999

Richeaux et al., 2000.

Nagabushan and Bhide, 1985 Villasenor et al., 1993

Villasenor and de Campo, 1994 Arceo et al., 1995

(continued)

196

TABLE 10.4 (continued) Test

Result

Notes

Citation

Dominant lethal sperm mutation

()

Narasimhamurthy and Narasimhamurthy, 1988

Carcinogenicity

()

Adult mice, injected i.p. at 0.4, 0.8, and 1.6 mg/day for 5 days (doses that are 1/10, 1/20 and 1/5 of the LD50. No changes in sperm count, testicular weight or histology, No change in sperm head abnormality, no dominant lethal mutants during an 8-week sequential mating schedule. Capsaisin (65% purity) in the food at doses up to 1%, for 35 days increased duodenal tumors in Swiss Mice. Chili extract promotes stomach and liver tumors in mice. Rodent bioassay showed increases in benign tumors (polyploid adenomas) but no malignant tumors. Dosed feed study in mice for 79 weeks with up to 0.25% capsinoid; no tumors. Capsaicin enhanced effect of 12O-tetradecanoylphorbol-13-acetate (TPA) in promoting induction of skin cancer. 0.42 mM topical application to skin prevented tumor induction by vinyl carbamate (VC) or Nnitrosodimethylamine (NMDA); both VC and NMDA require metabolic activation; capsaicin blocks the metabolic activation. Inhibited liver and lung carcinogenesis induced by diethylnitrosamine (DEN), N-methyl nitrosourea (MNU), and N-dibutylnitrosamine (DBN). Alone did not cause cancers.

() () () Co-carcinogenicity

()

Anti-carcinogenicity

()

()


Toth et al., 1984 Agrawal et al., 1986 Toth and Gannet, 1992 Akagi et al., 1998 LaHann, 1986 Surh et al., 1995

Jang et al., 1991


10.4 CONCLUSIONS The riot control agents CS, CN, CR and capsaicin (active ingredient of oleoresin capsicum (“pepper spray”) ) are very potent irritants at very low concentrations and have a large margin of safety. None have been shown to be carcinogens. Genotoxic effects have been demonstrated for CS and capsaicin, but usually in cultured cells and at micromolar concentrations. These levels would not normally be achieved in field use. However, exposure to high concentrations in confined spaces should be avoided.

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GANNETT, P.M., NAGEL, D.L., REILLY, P.J., LAWSON, T., SHARPE, J., and TOTH, B. (1988) The capsaicinoids: their separation, synthesis and mutagenicity, Journal of Organic Chemistry, 53:1071–1074. GOPINATH, C., PRENTICE, D. E., and LEWIS, D. J. (1987) The respiratory system. In: Atlas of Experimental Toxicologic Pathology, Current Histopathology, G.A. GRESHAM (ed.), Norwell MA: MTP Press, pp. 22–42. GRAWE, J., NUSSE, M., and ADLER, I.-D. (1997) Quantitative and qualitative studies of micronucleus induction in mouse erythrocytes using flow cytometry. I. Measurement of micronucleus induction in peripheral blood polychromatic erythrocytes by chemicals with known and suspected genotoxicity, Mutagenesis, 12: 1–8. JANG, J.J., CHO, K.J., LEE, Y.S., and BAE, J.H. (1991) Different modifying responses of capsaicin in a wide-spectrum initiation model of F344 rat, Journal of Korean Medical Science, 6: 31–36. KIM, J.P., PARK, J.G., LEE, M.D., HAN, M.D., PARK, S.T. et al. (1985) Co-carcinogenic effects of several Korean foods on gastric cancer induced by N-methyl-N-nitrosoguanidine in rats, Japanese Journal of Surgery, 15: 427–437. LAHANN, T.R. (1986) Effect of capsaicin on croton oil and TPA induced tumorigenesis and inflammation, Proceedings of the Western Pharmacology Society, 29: 145–149. LAWSON, T. and GANNETT, P. (1989) The mutagenicity of capsaicin and dihydrocapsaicin in V79 cells, Cancer Letters, 48: 109–113. LEE, J.K., PARK, B.J., YOO, K.Y., and AHN, Y.O. (1995) Dietary factors and stomach cancer: a case-control study in Korea, International Journal of Epidemiology, 24: 33–41. LOPEZ-CARILLO, L., AVILA, M.H., and DUBROW, R. (1994) Chili pepper consumption and gastric cancer in Mexico: a case-control study, American Journal of Epidemiology, 139: 263–271. MARRS, T.C., GRAY, M.I.H., COLGRAVE, H.F., and GALL, D. (1982) A repeated dose study of the toxicity of CR applied to the skin of mice, Toxicology Letters, 13: 259–265. MARRS, T.C., COLGRAVE, H.F., and CROSS, N.L. (1983a) A repeated dose study of the toxicity of technical grade dibenz-(b.f.)-1,4 oxazepine in mice and hamsters, Toxicology Letters,17: 13–21. MARRS, T.C., COLGRAVE, H.F., CROSS, N.L., GAZZARD, M.F., and BROWN, R.F.R. (1983b) A repeated dose study of the toxicity of inhaled 2-chlorobenzylidene malonitrile (CS) aerosol in three species of laboratory animal, Archives of Toxicology, 52: 183–198. MCGREGOR, D.B., BROWN, A., CATTANACH, P., EDWARDS, I., MCBRIDE, D., and CASPARY, W.J. (1988) Responses of the L5178Y tk /tk- mouse lymphoma cell forward mutation assay II: 18 coded chemicals, Environmental and Molecular Mutagenesis, 11: 91–118. MESHRAM, G.P., MALINI, R.P., and RAO, K.M. (1992) Mutagenicity evaluation of riot control agent o-chlorobenzylidene malononitrile (CS) in the Ames Salmonella/microsome test’, Journal of Applied Toxicology, 12: 377–384. MILLER, B.M. and NUSSE, N. (1993) Analysis of micronuclei induced by 2-chlorobenzylidene malonitrile (CS) using fluorescence in situ hybridization with telomeric and centromeric DNA probes, and flow cytometry, Mutagenesis, 8: 35–41. NAGABHUSHAN, M. and BHIDE, S.V. (1985) Mutagenicity of chili extract and capsaicin in short term tests, Environmental Mutagenesis, 7: 881–888. NARASIMHAMURTHY, M. and NARASIMHAMURTHY, K. (1988) Non-mutagenicity of capsaicin in albino mice, Food and Chemical Toxicology, 26: 955–958. NESTMAN, E.R. and LEE, E.G.-H., MATULA, T.I., DOUGLAS, G.R., and MUELLER, J. (1980) Mutagenicity of constituents identified in pulp and paper mill effluents using the Salmonella/mammalian microsome assay, Mutation Research, 79: 203–212. NESTMAN, E.R. and LEE, E.G.-H. (1983) Mutagenicity of constituents of pulp and paper mill effluent in growing cells of Saccharomyces cerevisias, Mutation Research, 119: 273–280. NTP (1990a) National Institutes of Health, Toxicology and carcinogenesis studies of 2-chloracetophenone (CAS No 532-27-4) in F344/N rats and B6C3F1 mice (inhalation studies), NTP TR 379, National Toxicology Program, Research Triangle Park, NC.



NTP (1990b) National Institutes of Health, Toxicology and carcinogenesis studies of CS2 (94% o-chlorobenzalmalononitrile) (CAS no 2698-41-1) in F344/N rats and B6C3F1 mice (inhalation studies), NTP TR 377, National Toxicology Program, Research Triangle Park, NC. NUSSE, M., RECKNAGEL, S., and BEISKER, W. (1992) Micronuclei induced by 2-chlorobenzylidene malonitrile contain single chromosomes as demonstrated by the combined use of flow cytometry and immunofluorescent staining with anti-kinetochore antibodies, Mutagenesis, 7: 57–67. OLAJOS, E.J. and SALEM, H. (2001) Riot control agents: pharmacology, toxicology, biochemistry and chemistry, Journal of Applied Toxicology, 21: 355–391. PETTIJOHN, D.E. and HANAWALT, P.C. (1964) Evidence for repair replication of ultraviolet damaged DNA in bacteria, Journal of Molecular Biology, 9: 203–212. PINDBORG, J.J., POULSEN, H.E., and ZACHARIAH, J. (1967) Oral epithelial changes in thirty Indians with oral cancer and submucous fibrosis, Cancer, 20: 1141–1146. RICHEAUX, F., CASCANTE, M., ENNAMANY, R., SABOUREAU, D., and CREPPY, E.E. (1999) Cytotoxicity and genotoxicity of capsaicin in human neuroblastoma cells SHSY-5Y, Archives of Toxicology, 73: 403–409. RICHEAUX, F., CASCANTE, M., ENNAMANY, R., SANCHEZ, D., SANNI. A., SABOUREAU, D., and CREPPY, E.E. (2000) Implications of oxidative stress and inflammatory process in the cytotoxicity of capsaicin in human endothelial cells: lack of DNA strand breakage, Toxicology, 147: 41–49. RIETVELD, E.C., DELBRESSINE, L.P.C., WAEGEMAEKERS, T.H.J.M., and SEUTTER-BERLAGE, F. (1983) 2-Chlorobenzylmercapturic acid, a metabolite of the riot control agent 2-chlorobenzylidene malononitrile (CS) in the rat, Archives of Toxicology, 54: 139–144. ROSENKRANZ, H.S. and KLOPMAN, G. (1993) Structural relationships between mutagenicity, maximum tolerated dose, and carcinogenicity in rodents, Environmental and Molecular Mutagenesis, 21: 193–206. SALASSIDIS, K., SCHMID, E., and BAUCHINGER, M. (1991) Mitotic spindle damage induced by 2-chlorobenzylidene malonitrile (CS) in V79 Chinese hamster cells examined by different staining of the spindle apparatus and chromosomes, Mutation Research, 262: 263–266. SASAJIMI, K., WILLEY, J.C., BANKS-SCHLEGEL, S.P., and HARRIS, C.C. (1987) Effects of tumor promoters and co-carcinogens on growth and differentiation of cultured human esophageal Epithelial Cells, Journal of the National Cancer Institute, 78: 419–958. SCHMID, E., BAUCHINGER, M., ZIEGLER-SKYLAKAKIS, K., and ANDRAE, U. (1989) 2-Chlorobenzylidene malonitrile (CS) causes spindle disturbances in V79 Chinese hamster cells, Mutation Research, 226: 133–136. SCHMID, E. and BAUCHINGER, M. (1991) Analysis of the aneuploidy inducing capacity of 2-chlorobenzylidene malonitrile (CS) and metabolites in V79 Chinese hamster cells, Mutagenesis, 6: 303–305. SIRSAT, S.M. and KHANOLKAR, V.R. (1962) Submucous fibrosis of the palate and pillars of the fauces, Indian Journal of Medical Science, 16: 189–197. SURH, Y.-J. and LEE, S.S. (1995) Capsaicin, a double-edged sword: toxicity, metabolism and chemopreventive potential, Life Sciences, 56: 1845–1855. SURH, Y.-J, LEE, E., and LEE, J.M. (1998) Chemoprotective properties of some pungent ingredients present in red pepper and ginger, Mutation Research, 402: 259–267. SURH, Y.-J., LEE, R.C.-J., PARK, K.-K, MAYNE, S.T., LIEM, A., and MILLER, J.A. (1995) Chemoprotective effects of capsaicin and diallyl sulfide against mutagenesis or tumorigenesis by vinyl carbamate and N-nitrosodimethylamine, Carcinogensis, 16: 2467–2471. TAJIMA, K. and TOMINAGA, S. (1985) Dietary habits and gastro-intestinal cancers: a comparative case control study of stomach and large intestinal cancers in Nagoya, Japan, Japanese Journal of Cancer Research, 76: 705–716. TOTH, B. and GANNETT, P. (1992) Carcinogenicity of lifelong administration of capsaicin of hot pepper in mice, In Vivo, 6: 59–63. TOTH, B., ROGAN, E., and WALKER, B. (1984) Tumorigenicity and mutagenicity studies with capsaicin of hot peppers, Anticancer Research, 4: 117–119.


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UNGSURUNGSIE, M., SUTHIENKUL, O., and PAOVALO, C. (1982) Mutagenicity screening of Popular Thai spices, Food and Chemical Toxicology, 20: 527–530. VENITT, S., CROFTON-SLEIGH, C., and FORSTER, R., (1984) Bacterial mutation assays using reverse mutation. In: S. Venitt, and J.M. Parry, (eds), Mutagenicity Testing: A Practical Approach, Oxford: IRL Press Ltd, pp. 45–99. VILLASENOR, I.M. and DE OCAMPO, E.J. (1994) Clastogenicity of red pepper (Capsicum frutescens L.) extracts, Mutation Research, 312: 151–155. VILLASENOR, I.M., DE OCAMPO, E., and BREMER, J.B. (1993) Effect of natural capsaicin on bone marrow cells of mice, Philippine Journal of Science, 122: 397–402. VON DANIKEN, A., FREDERICH, U., LUTZ, W., and SCHLATTER, C. (1981) Tests for mutagenicity in Salmonella and covalent binding to DNA and protein in the rat of the riot control agent o-chlorobenzylidene malononitrile (CS), Archives of Toxicology, 49: 15–27. WILD, D., ECKHARDT, K., HARNASCH, D., and KING, M.-T. (1983) Genotoxicity study of CS (Orthochlorobenzylidene malononitrile) in Salmonella, Drosophila, and mice, Archives of Toxicology, 54: 167–170. YANG, W.L., KLOPMAN, G., and ROSENKRANZ, H.S. (1992) Structural basis of the in vivo induction of micronuclei, Mutation Research, 272: 111–124. ZEIGER, E., ANDERSON, B., HOWORTH, S., LAWLOR, T., MORTELMANS, K. and SPECK, W. (1987) Salmonella mutagenicity tests III. Results from the testing of 225 chemicals, Environmental Mutagenesis, 9: 1–109. ZIEGLER-SKYLAKAKIS, K., SUMMER, K.H., and ANDRAE, U. (1989) Mutagenicity and cytotoxicity of 2-chlorobenzylidene malonitrile (CS) and metabolites in V79 Chinese hamster cells, Archives of Toxicology, 63: 314–319.


CHAPTER

Human Exposures to Riot Control Agents

11

WOODHALL STOPFORD1 AND FREDERICK R. SIDELL2 1 Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, USA 2

Consultant, 14 Brooks Road, Bel Air, MD 21014, USA

11.1 INTRODUCTION This chapter examines the effects of riot control agents (RCAs) when humans are exposed either under controlled conditions or during their use. We present information on 1-chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS), dibenz[b,f]1:4oxazepine (CR), oleoresin capsicum (OC) and natural capsaicinoids and two synthetic components of OC, capsaicin and n-nonanoyl vanillylamide (VAN). We have paid particular attention to those studies that have shown persistent adverse effects related to intentional or unintentional high level acute exposures. When the data are available we present acute and subacute inhalation doses in terms of concentrationtime (Ct) in units of mg-min/m3. For each RCA we examine threshold concentrations where 50% of an exposed population will just react to exposure (TC50 in terms of mg/m3 or molar concentrations (M)) and those where 50% of a population will leave an exposure situation because of irritant effects (ICt50 in terms of mg-min/m3 or molar concentrations (M)). Many of the technical terms used in describing effects of RCAs to humans are technical or medical. Please see the Appendix A on terminology for definitions for these terms. The riot control agents CN, CS, CR, OC, and VAN are currently in use by police, correction officers, or the military in various countries. Capsaicin is the most potent component of OC and is currently not available as an RCA. There is, however, a large database on its use in experimental animals and man because of its properties of depleting substance P and interfering with the function of sensory C fibers. By blocking their function, investigators can determine the physiological significance of these fibers. It is used in man as a topical agent for controlling pain in various disorders including diabetic neuropathy and post-herpetic neuralgia and as a treatment for chronic rhinitis. Finally, it is a major tool in the armamentarium of respiratory physiologists and physicians for studying patients who have chronic cough. It is not surprising then that the weight of human studies involving exposures to capsaicin are for inhalation and skin exposures. Oleoresin capsicum is an extract of chili pepper plants that contains a number of capsaicinoids. Of these capsaicinoids, 80–90% comprise of capsaicin and dihydrocapsaicin, components with similar irritating properties; 1–2% of the capsaicinoids in OC are made up of VAN. There is, however, a great deal of variability in the concentrations of active ingredients from one OC product to the next and there is a large batch-to-batch variation in the concentration of capsaicinoids for any one OC product (Reilly et al., 2001). Consequently attempts by us to determine capsaicinoids exposures from published experiments may have limited utility. There has been a great deal of interest in the effects of OC


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since chili powder is a major component of the cuisine of many societies. Because of this there are an inordinate number of studies involving the chronic dosing of chili pepper, OC, or its components. Chili peppers may, contain toxic materials other than capsaicinoids (such as aflatoxins) that may influence the outcome of chronic dosing studies.

11.2 CN 1-chloroacetophenone (CN) was used in the First World War and has been used in tear gas guns and tear gas grenades through the 1960s. Although its use in personal defense sprays and as a tear gas has been supplanted with less toxic RCAs, it is still used for riot control and in personal defense sprays law enforcement agencies of at least three countries (Independent Commission on Policing for Northern Ireland, 2001).

11.2.1 Threshold effects Kane et al. (1979) noted the following concentration-related effects for CN exposures in man (Table 11.1). McNamara et al. (1969) noted that the Human Estimates Committee set the ICt50 for CN at 40 mg-min/m3 when CN is dispersed in acetone and 20 mg-min/m3 when dispersed by grenade.

11.2.2 Inhalation The National Research Council (1984) reviewed 69 inhalation exposures to CN at Edgewood Arsenal between 1958 and 1972. Subjects were exposed to 6–315 mg-min/m3 CN. The effects of inhalation exposures were transient and included blepharospasm, tearing, conjunctivitis, and rarely, eyelid edema. Respiratory effects included chest irritation, nasal discharge and, rarely, shortness of breath. There was no evidence of exposurerelated asthma, even with repeat exposures. Punte et al. (1962) exposed subjects to a maximum of 350 mg-min/m3 of CN and examined them before, immediately after, and 2–4 days after exposure. Median particle sizes were 0.6–1.1 m. The concentration necessary to produce irritation in 50% of the subjects (ECt50) in 1 min was 213 mg/m3. The 2 min ECt50 value was 119 mg-min/m3 and the 3 min ECt50 value was 93 mg-min/m3. Exposures to CN were associated with symptoms of tearing, burning of the eyes, and blurred vision; nasal discharge and nasal irritation; and burning of the throat and chest, and difficulty in breathing. Airway resistance appeared to increase at times.

TABLE 11.1 CN: Biological effects and exposure concentrations (humans) Effect

Concentration (mg/m3)

Respiratory symptoms and severe tearing/conjunctivitis Intolerable sensory irritation Sensory irritation but tolerable Minimal or no sensory irritation

4.5


3.3 0.3–0.4 0.06

HUMAN EXPOSURES TO RCA

11.2.3 Skin Holland and White (1972) studied the skin reactions in humans after CN exposure. Irritation started within 10 min of exposure and became more severe during the period of application. Irritation disappeared following removal of material but recurred transiently when washing affected area during the subsequent 12 h. In every instance diffuse redness affected up to 3 times the original contact area. At doses of over 2 mg there was also localized edema that subsided after 24 h. With quantities of 0.5–2 mg when applied dry the redness disappeared within 72 h. At higher doses and at all doses when applied moist the redness became raised and papular. The papules coalesced to form a ring of vesicles at about 48 h. Two weeks later the lesions were evident as faint areas of hyperpigmentation.

11.2.4 Sensitization Marzulli and Maibach (1974) tested normal human subjects to CN using a modified Driaze patch test procedure. Repeated insults of 0.5 gm of 1% CN applied under an occlusive dressing every 48–72 h were delivered to skin over 3–5 weeks followed by a 2-week rest and then a challenge contact. The applications were applied successively at the same site. Challenge was done with non-irritating concentrations of CN. On challenge, 7 of 10 participants reacted to a 0.1% CN concentration but not to a 0.01% concentration. The data were regarded as showing CN to be a strong sensitizer. Penneys et al. (1969) describe the induction of sensitization to CN by patch testing under an occlusive dressing to a 0.9% concentration for 24 h. Challenges were done with 0.009% CN (a non-irritating concentration) at 7, 14, 21 days under occlusive patch for 48 h. The authors were able to sensitize two individuals after one induction exposure and another two with repeated induction exposures. All four were positive to the patch tests. Eight naïve controls also received 0.009% patch tests repeatedly and three became sensitized.

11.2.5 Tear gas gun injuries Tear gas guns were used commonly from the 1920s to the 1960s. These guns, as well as CN grenades, contained 10–23% CN (MacRae et al., 1970). Their discharge was associated with pressures of up to 20 atmospheres. Discharges close to the eyes or skin could result in both penetrating wad injuries as well as extremely high exposures to CN, often with penetration of particles through the outer layers of the skin or eyes. Chronic effects would occur secondary to the persistent effects of embedded CN particles (Ballantyne, 1977). Effects associated with these injurious exposures included chronic keratitis, corneal ulcers, and corneal inflammation to the point of vascularization and loss of vision, glaucoma, and eye damage requiring removal of the eye. Soft tissue injuries occurred with associated nerve damage. Hoffmann (1967) observed over 50 cases of eye injuries from shots of tear gas fired into eyes at close range. He found that CN powder infiltrated into conjunctiva and cornea. In most cases there was initial corneal edema and superficial erosion that followed in a few days by clouding of the cornea. Late vascularization of cornea occurred. These effects were seen with shots from 10 cm to 2 m from the eye. The author discounted thermal effects. Oaks et al. (1960) describe a patient who was shot in the face at close range with a CN tear gas gun. The wadding hit him above his right eye. When first seen his face showed edema, generalized redness, and vesiculation. At 12 h post-injury, the left eye still showed chemosis and mild injection. The eyelids of right eye were swollen to the point of rigidity. The conjunctiva was edematous and hemorrhagic. His right cornea was white. At


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52 days after injury he continued to complain of pain: his right globe was stony hard and was enucleated for pain relief. A pathological examination showed that the iris was vascularized and fibrotic and that there was optic nerve atropy. Levine and Stahl (1968) described findings in 13 individuals who lost one or both eyes after tear gas gun or grenade injuries. Injuries were associated with intense eye pain, corneas were opaque, vascularized, scarred and/or ulcerated. There were anterior chamber exudates or debris. Glaucoma occurred in a few cases. Pathological examinations disclosed intense, suppurative, necrotizing keratitis and coagulative necrosis in the deep aspects of corneas. The authors felt that the major risk was from “tear gas” itself as opposed to blast fragments. Adams et al. (1966) evaluated 3 cases of penetrating hand injuries from tear gas pen guns. Even with debridement, there was thickening of tendon sheaths and nerve sheaths with associated loss of sensation and pain with hand flexion movements. In rabbit model, they found that CN sprinkled on sciatic nerve resulted in inflammation and edema and paralysis. Nerve conduction was absent and adjacent muscles were friable.

11.2.6 Acute persistent – eyes (self defense sprays) Ballantyne (1977) reviewed cases of eye damage from use of CN sprays. They review the report of Rose (1969) where 12 cases where evaluated with fluorescein staining of cornea. Findings were normal within 72 h in nine cases, but extensive injury requiring 14–21 days for healing occurred in three. Oksala and Salminen (1975) describe five patients who were hospitalized by eye injuries caused by CN sprays discharged close to the face. There was severe swelling and injection of the lids and conjunctiva in all cases. Epithelial defects, swelling, and blurring of the parenchyma were observed in the corneas. Healing required weeks to months.

11.2.7 Acute persistent – inhalation Thorburn (1982) describes hospitalizations after CN was released into 44 prisoner cells. Eight prisoners required hospitalization and 20 more received outpatient physician care for injuries. Five of the eight hospitalized prisoners had pseudomembranes in their throats. Three developed tracheobronchitis requiring the use of bronchodilators. In one, bronchodilator therapy continued for three months. Vaca et al. (1996) describe a case where CN spray was used mistakenly as room deodorizer. Eighteen, hours after exposure began, the individual presented with shortness of breath and pulmonary edema on X-ray. There was worsening edema for several days after admission which reversed with the use of glucocorticosteroids. Gonzales et al. (1954) describe a death that resulted from exposure to CN in enclosed space as a result of police action. At autopsy there was a secondary bronchopneumonia from inflammation of the lungs and airway passages. Chapman and White (1978) describe an individual who died after being exposed to CN and CS. CN was used during a prison riot. Fourteen 100 g CN projectiles, six CN grenades, 0.4 L of 8% CS, and 4–5 min bursts of CS via fogger were used. The authors calculate that prisoner could have been exposed to as much as 41,000 mg-min/m3 CN from use of the projectiles. The subject was found dead in his cell 46 h after initial gassing. There was extensive necrosis of the mucosal epithelium of the larynx, trachea, and bronchi with replacement by a pseudomembrane. There were areas of consolidation in the lungs. Stein and Kirwan (1964) report a death that occurred after a 29-year-old man was exposed to 128 g of CN in a room of approximately 70 cubic feet for 30 min. When



admitted he was semicomatose. After 12 h he developed pulmonary edema and died. At autopsy the larynx, tracheal, and bronchi were swollen and covered by a pseudomembrane. There was acute necrosis of respiratory mucosa and desquamation of epithelium in many of bronchioles. There was pulmonary edema and alveoli were filled with protein-rich fluid and, in some places, lined with hyaline membranes. There was brain swelling with tonsillar herniation. Sidell (1997) estimates that exposure to CN in this case was 142,500 mg-min/m3, 10-fold above the estimated human lethal dose. The authors document three additional unpublished deaths associated with CN exposure. In each case the affected individual was exposed in a confined and relatively small space for 10 min to hours. Autopsy findings were similar to those found in this case.

11.2.8 Acute persistent – skin Thorburn (1982) describe hospitalizations after CN was released into 44 prisoner cells. Eight prisoners required hospitalization and 20 more received outpatient physician care for injuries. Of those hospitalized, four had facial burns and three had burns around their ankles. In the most severely affected, there were first and second degree burns over 25% of his body. One had an allergic-type of reaction starting 72 h after exposure and one had an asthmatic reaction starting 1–2 days after exposure. Among those not hospitalized (36), 10 had first and second degree chemical burns, and six had allergic-type rashes starting 2–7 days after exposure. Two of these latter required antihistamines for three months to control rashes. Fuchs and in der Wiesche (1990) interviewed 56 occasional demonstrators and performed patch testing with a 0.0010% solution of CN. Twenty-one were exposed to CN or CS 5 times, 31 were exposed 5–50 times and four were exposed 50 times. Thirtyeight subjects were exposed to both CN and CS. Subjects (59%) had reported burning, itching, reddening, and swelling of their skin. One individual noted a week-long itching rash associated with swelling, burning, reddening, blister formation, and bleeding. Skin reactions were noted in 14/16 coming in contact with CN. On patch testing eight showed questionable to slightly positive reactions: four to both CN and CS and four to CN only. Madden (1951) described a law enforcement officer who used old CN grenades to try and eradicate rodents. He developed a severe dermatitis on his legs with each use over a period of 5 years. A small area of one leg was intentionally exposed to CN tear gas: an acute contact dermatitis appeared subsiding within 8 h.

11.2.9 Acute delayed – sensitization Sidell (1997) notes that because of the high incidence of sensitization in test subjects exposed to CN, this RCA should be considered a potent sensitizer and those who are frequently exposed should be aware of the high likelihood of developing allergic contact dermatitis. Maucher et al. (1986) describe a patient with allergic contact dermatitis, which first appeared 5 days after exposure to CN. With testing against 0.01% CN, a papular rash developed while a 0.1% exposure resulted in a vesicular rash. Queen and Stander (1941) describe an allergic reaction that developed in a 43-year-old physician who went through CN training chamber routine (5-min exposure, removing mask during exposure). He had prior exposure 17 years before during a similar exercise at which time he had slight itching. Within 5 min, generalized itching developed and became progressively worse. Four hours after exposure a diffuse and intense redness developed over his entire body except his feet (wearing boots) and portion of face covered with his mask. His temperature rose to 39.4C the next day and continued to be elevated for


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several days. He developed vesiculation 48 h after exposure and later severe subcutaneous edema. Profuse desquamation started on day six and continued for the next 3–4 weeks. The authors felt that this reaction represented allergic hypersensitivity to CN.

11.3 CS o-chlorobenzylidene malononitrile (CS) is currently used as an RCA, as a personal defense spray and to assist in building entry by police forces of at least 10 countries (Independent Commission on Policing for Northern Ireland, 2001). It has been used by armed forces as a replacement for CN since 1959. Its use to assist building entry can result in high level exposures with increased risk for adverse skin and chest effects.

11.3.1 Thresholds Lundberg (1994) notes irritation thresholds for CS of 0.004 mg/m3 for eye effects, 0.023 mg/m3 for airway effects, 3.2 106 M (0.06 g) for corneal pain, and 7.3 107 M (0.014 g) for involuntary blinking. McNamara et al. (1969) note that the ICt50 values for CS are based on the results of 146 human exposures in seven experiments. They feel a range of values should be used: 0.1–10 mg/m3. From data summarized by McNamara et al. (1969), the National Research Council (1984) calculated the values of ICt50 for CS as in Table 11.2. The end point in each case was intolerance sufficient to leave exposure. The ICt50 values were calculated with a curvilinear regression line analysis.

11.3.2 Eye effects Eye effects have been evaluated after CS exposures to the eyes presented as drenches or showers, drops, sprays, or aerosols. The data on drenches and sprays may have limited usefulness. Exposure concentrations by these routes ranged from 0.003% to 1.0% whereas personal defense sprays usually have CS concentrations in the range 1–7%.

TABLE 11.2 ICt50 values for CS Vehicle

Concentration (mg/m3)

Aerosol in acetone (motivated) Aerosol in acetone (no motivation) Aerosol in acetone (no motivation) Vaporized methylene chloride solution (no motivation) Vaporized methylene chloride solution (motivated) CS dry powder aerosol (motivated)

5–442

78

4.7

0.3–8.0

35

0.7

0.02–5.4

30

0.2

0.40–0.90

21

0.6

0.50–28.0

130

6.9

30

0.5


0.3–6.7

No. of men

ICt50 (mg-min/m3)


Ballantyne et al. (1976 ) drenched fully clothed subjects with solutions of 0.003%, 0.003%, or 0.005% CS either in shower stalls for 15 s or out of doors for 60 s. Immediately after exposure, subjects commonly experienced stinging of their eyes, coughing, breathlessness, and nasal discharge. These symptoms were followed by unpleasant, though mild, skin stinging. Symptoms quickly diminished in a few minutes, disappearing within 10 minutes. Blood pressures increased by 5–50 mm Hg systolic and 0–40 mm Hg diastolic in 1–2 min after drenching, returning to normal in 2–13 min. The magnitude of the blood pressure rise generally related to magnitude of discomfort. Rengstorff and Mershon (1969) placed or sprayed 0.1% or 0.25% CS in water into the eyes of volunteers. Exposure resulted in intense blepharospasm lasting from 10 to 135 s and transient conjunctivitis. There was no corneal damage as assessed by slit lamp biomicroscopy. Rengstorff and Mershon (1971) further evaluated CS by spraying or placing one drop of 0.1% or 0.25% CS in water and 0.5% polysorbate 20 in to the eyes of volunteers. Exposure was associated with a burning sensation after 1–5 s, intense eye pain, and blepharospasm. Effects were worse with the CS aerosol than with the drops. Subjects began to experience relief in 3–4 min and had resolution of pain after 10 min. In this study, 1 of the 16 subjects developed fluorescein staining of the cornea that cleared by 24 h after exposure. There was no evidence of edema or damage to the epithelium or stroma of the cornea at 24 h, 8 days (spray) or 52 days (drops) after exposure. Weimer et al. (1975) instilled 1.0% CS in trioctyl phosphate into the eyes of 18 volunteers as a single drop or a brief spray. Subjects were unable to open their eyes for 20–85 s. Vision blurred for 70–450 s. There was no corneal damage on slit lamp biomicroscopy. Gutentag et al. (1960) exposed human subjects to CS in a wind tunnel at levels of 5 mg/m3. Eye symptoms were instantaneous and included severe conjunctivitis, tearing, a burning sensation, and eye pain. Pain disappeared abruptly 2–5 min after exposure stopped and conjunctivitis cleared in 25–30 min. Redness of eyelids generally remained for 60 min. Tearing lingered for as long as 12–15 min. Occasionally, there was blepharospasm. In 5–10% of subjects, marked photophobia lasting for up to one year in some cases were found. Rengstorff (1969) exposed 10 men to CS2 aerosol in a wind tunnel. Concentrations ranged from 0.1 to 1.7 mg/m3 and from 20 to 600 s at 0.1 mg/m3 with all exposures at higher concentrations for 60 s. In a second study he exposed 34 men to 0.4–1.0 mg/m3 CS in methylene chloride for 35–600 s. A third series of exposures was done with 22 men to 0.5–6.7 mg/m3 CS in methylene chloride for 10 min or more. Symptoms associated with exposure included intense eye irritation with blepharospasm, tearing, and marked conjunctival injection. There were no changes in visual acuity within minutes of exposure. During exposure, in those volunteers who could open their eyes (73%), visual acuity ranged from 20/20 to 20/30. At exposures 5 mg/m3 all subjects had intense eye irritation and most were unable to open their eyes during exposure, but for one who had an acuity of 20/30. Postexposure slit lamp and UV light examinations after fluorescein staining of the corneas revealed no abnormalities. Rengstorff (1968) exposed subjects to a powder of dispersed CS2 or CS powder thermally disseminated at concentrations of 0.1–6.7 mg-min/m3 for 20 s to 10 min. Visual acuity was tested during and after exposure. In those individuals who could keep their eyes opened, there was no decrement in acuity from baseline values.

11.3.3 Inhalation Controlled human exposures have been reported to respirable aerosols of CS at concentrations ranging from 0.16 to 94 mg/m3. With a gradual increase in exposure levels,


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tolerance to CS can develop. All tested individuals were, however, unable to tolerate concentrations of 10 mg/m3 for more than a minute. Cotes et al. (1972a) exposed 14 soldiers to 1 m CS aerosols during progressive exercise on a bicycle ergometer. CS concentrations ranged from 0.2 to 1.3 mg/m3. There was increased heart rate at rest and with exercise during exposure but ventilation minute volume did not change significantly. Cotes et al. (1972b) used a single breath CO method to determine alveolar volume and diffusion capacity. They evaluated 11 men exposed to 0.6–2.0 mg/m3 CS for over 1 h. They found very small transient decreases in gas exchange during exposure thought to be secondary to changes in vascular tone and blood volume in the lung capillaries. The alveolar volume did not change with no evidence of constriction of smooth muscles of airways sufficient to cause air trapping. Gas exchange returned to normal within 2 h of exposure. The authors note that they see similar changes in blood flow (and associated gas exchange) with exercise, excitement, heat exposures, or apprehension. McNamara et al. (1969) summarize experiments where human subjects were exposed to various concentrations of CS for up to 300 seconds. Incapacitating effects were found to include intense burning of the eyes, nose, and respiratory tract, profuse tearing and salivation, blepharospasm, chest tightness, and a feeling of suffocation. When a tolerant person left room for 10–30 min, intolerance returned. Men could tolerate 1.5 mg/m3 CS for 90 min or 6 mg/m3 CS for 30 min when concentrations were gradually built up over 30 min. No significant differences in incapacitating dose could be found based on exposure to an aerosol vs a grenade, at room temperature vs 0F, in men over 50 vs those in their 20s, and in men with allergies vs no allergies. There was a possible decrease in time to incapacitation with a temperature of 95F vs room temperature either with a relative humidity of 35% or 97%. Beswick et al. (1972) exposed volunteers to CS for 60 min. Concentrations were slowly raised from 0.43 to 2.0 mg/m3. This exposure did not affect flow, tidal volume, vital capacity, or EKGs. Once exposure ceased all symptoms and signs, apart from headache, disappeared in a few minutes. If men were able to stand the initial effects, they were able to tolerate higher concentrations as well. Cole et al. (1975) exposed 17 men to 0.4–4.4 mg/m3 CS during progressive submaximal exercise testing and compared the effects to those of exposures to 50–340 mg/m3 of ammonia. In this exposure range the cardiorespiratory effects were small in relation to the intense discomfort subjects experienced and not much different from effects seen with ammonia at exposure levels that were only associated with minimal symptoms. With both exposures there was a slight reduction in ventilation frequency and, at higher doses, a reduction in tidal volume accompanied by an increase in breathing rates. Cole et al. (1977) further measured ventilation minute volume, tidal volume, and heart rate during submaximal exercise performed by male volunteers exposed to CS and ammonia gas in concentrations of 0.16–4.4 mg/m3 (1.3–35 mg-min/m3) and 50–344 mg/m3, respectively. Exposures to CS were progressively increased over 120 min with exposures averaging 0.3–0.9 mg/m3. Ventilation minute volume was reduced by 6% associated with a reduction in tidal volume and a rapid breathing rate. Gutentag et al. (1960) exposed human subjects to CS aerosols at various concentrations. Time for incapacitation for untrained subjects was 50 s for exposures at 5 mg/m3 and greater. With high temperatures and humidity (95F, 97% RH) skin burning was more prominent particularly in areas of sweating. Blood pressure was elevated in some subjects, particularly those with a history of hypertension. Blood pressures normalized within 15 min after exposure. The maximum recorded blood pressure rise was 60 mm Hg systolic and 50 mm Hg diastolic. Individuals with a history of allergies, hay fever or asthma were more likely to have chest symptoms and symptoms were more severe than in those without this history. Symptoms included profuse nasal discharge and salivation, burning of



the throat and chest, occasional coughing, and constriction of the chest often accompanied by panic. Individuals who had panic appeared not to be able to breath in or out. Most subjects were aphonic for 1–2 min after exposure and several were hoarse for 24 h. The authors felt that these symptoms could reflect reflex laryngospasm. Chest symptoms were not helped by epinephrine, isoproterenol, or prophylactic atropine. Airway resistance did not increase after 4 or 10 exposures. Himsworth et al. (1971) report on a number of investigations that were done to determine whether or not exposures to CS during riots in Londonderry in August 1969 could have put rioters at risk of ill health. They estimate that average CS exposure during these riots was 90 mg-min/m3. 1

2

3

4 5

6

They investigated whether or not exposure was associated with a risk of liver disease. For the period from August 1968 through July 1969, 41 cases of hepatitis were reported in Londonderry, 11 from inhabitants of district where CS was used. From August 1969 through May 1970, 30 additional cases of hepatitis were reported, nine were in individuals over age 12 but only four occurred in persons living in districts where CS had been used. The Committee felt that there was no evidence of risk of liver disease related to acute CS exposures. A study was done where 34 adults were exposed to CS for 1 h for a Ct of 90 mg-min/m3. Significant increases in total white blood cell, neutrophil, and monocyte counts occurred immediately after exposure. There were increases in SGPT immediately after exposure but the elevation was not significant at 24 h. There were no changes in BUN, SGOT, and alkaline phosphatase. The Committee did not consider the changes to be effects of any significance to health. A study was done where 12 healthy men were exposed for 1 h to 0.6–2.0 mg/m3 CS. There were no changes in lung volumes or carbon monoxide diffusion associated with exposure. Another study was done where 15 healthy men were exposed to 1 mg/m3 CS while exercising. CS produced a 6% reduction in ventilation rate at a constant workload. Death rates from bronchitis, emphysema, and asthma in Londonderry County Borough were determined for the years 1965–69, bracketing exposure of residents to CS in August 1969. The standardized mortality ratio (SMR) for death associated with these diseases for males ranged from 118 to 189 for the years 1965–68. For 1969 the SMR for these diseases was 161. For women SMR values ranged from 123 to 233 for the period 1965–68 and was 217 for deaths from these diseases in 1969. Patterned breathing was evaluated in individuals exposed to 50 mg/m3 CS for about one minute. CS produced periods of apnea lasting for up to 10 s. Minute ventilation dropped in half in some individuals but there was no impairment in gas exchange.

Owens and Punte (1963) exposed six subjects to CS in a wind tunnel for 60 s at concentrations ranging from 85 to 94 mg/m3. With exposures to a small (0.9 m) aerosol 40% tolerated eye effects vs 100% who could tolerate similar exposures to a large (60 m) CS aerosol. Of those exposed to the 0.9 m aerosol, 100% found respiratory effects intolerable in 30 s. In contrast, 67% of those with large aerosol exposures could tolerate chest effects for 1 min. For small particles the recovery time for eye effects averaged 91 s and for chest effects 51 s. For large particles the recovery time for eye effects was 280 s and for chest effects 9 s. Punte et al. (1963) exposed volunteers to 0.5–1.0 m aerosols of CS in a wind tunnel and measured response times (to intolerance) in seconds to one minute. Response times


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were 35 s or less at exposures of 20–94 mg/m3. At 10 mg/m3, response times ranged from 15 to 60 s. Response times were reduced with high temperature and humidity or with exercise. In one group exposed 10 times for over 2 weeks to concentrations ranging from 1 to 13 mg/m3, blood electrolytes, alkaline phosphatase, chest X-rays, and urinalyses were normal and airway resistance did not vary from baseline. In 36 subjects, tidal volume, vital capacity, and peak flow were measured at 2–4 min and 24 h after exposure, which changed from baseline.

11.3.4 Inhalation – tachyphylaxis Beswick et al. (1971) exposed eight groups of volunteers to CS2 for 60–90 min. Exposures began at 0.56–0.84 mg/m3 and were boosted at intervals up to 2.3 mg/m3. Men became habituated though symptoms were exacerbated at boosts in exposure concentration. Those who were placed in the exposure chamber wearing masks were forced to rush out of chamber at the end of hour when unmasked while those who were habituated could continue exposure. There was a slight rise in blood pressure and pulse rate at 10 min after the start of exposure but values retuned to normal within 20 min. Punte et al. (1963) exposed volunteers to 0.5–1.0 m aerosols of CS in a wind tunnel. The authors found that men could tolerate exposures to 1.5 mg/m3 CS for 90 min and to 6.6 mg/m3 as long as concentrations were gradually built up over 30 min. With these repeated low-level exposures to induce tolerance, accuracy of simple problem solving was not impaired. If concentration were built up to 6 mg/m3 over 10 min, three of four subjects had to leave.

11.3.5 Ingestion Sidell (1997) reports on the findings of individuals who ingested CS. Typically children were playing in an old impact area on a military installation and came across some shells containing a powdery substance which they ate. One adult ate CS in an attempted suicide. Another adult ate a CS pellet (820 mg) thinking it was a vitamin pill. No deaths occurred. In the case of the attempted suicide, the patent was treated with saline cathartics. Over the ensuing 24 h he had repeated episodes of severe abdominal cramps and diarrhea. He recovered uneventfully. In the case of the adult who ate the CS pellet, he vomited twice, had six voluminous watery stools without blood and otherwise recovered uneventfully. His blood cyanide level was 1 g/dL, 18 h after ingestion.

11.3.6 Skin A number of studies have evaluated the response of human skin to CS applied in the liquid form (in concentrations ranging to 20%), as a solid or as an aerosol (in concentrations ranging to 300 mg/m3). Exposures to skin only by aerosol were made possible by having subjects place their arms through a sleeve into the exposure chamber. Exposures by this method can result in any changes from temporary redness to second degree chemical burns. The likelihood of developing a more severe reaction increases with increasing exposures (in terms of mg-min/m3), including those that are a result of delayed decontamination, with sweating or when there is prior skin damage, even minor abrasions. Blister formation is usually accompanied by edema, probably related to alkylation of tissue components. Healing of second degree chemical burns is usually accompanied by pigmentation changes while healing of third degree burns is accompanied by scarring.



Foster and Weston (1986) applied 0.04 mL CS solutions to a blister base for a maximum of 1 min and scored the degree of pain associated with exposure. Repeated exposures to 100 M CS were associated with pain and then desensitization to pain. Weigand et al. (1969) patch tested 10 volunteers to CS1 solutions ranging in concentration from 0.01% to 1.0%. At room temperature CS1 at 0.5% and higher caused delayed redness, that is, an irritant dermatitis if exposures were for longer than 5 minutes. All concentrations caused moderate to severe stinging. Weimer et al. (1975) applied CS in concentrations of 0.1–1.0% in uncovered patches to the foreheads of five volunteers at ambient temperatures of either 75–80 F or 105 F. Immediate redness occurred at all concentrations and at both temperatures. There was no persistent dermatitis. Shmunes and Taylor (1973) patch tested two men with 1% CS in olive oil for 12 h. This treatment produced tender reddish lesions. By 24 h edema was evident and by 48 h bullae had developed. Healing was complete in two weeks. Gutentag et al. (1960) noted that patch testing disclosed that CS is potentially a severe skin irritant. Patch testing of 10% CS methylene chloride was associated with no reaction; but mild redness and vesicle formation was seen in two of four subjects when exposed to 20% CS. Weigand and Mershon (1970a) patched tested 39 subjects to 0.18–0.22 mg CS2 powder under occlusive dressings, determining the time to perceptible redness. Patches were placed on the face, forearm, or back with or without the stratum corneum removed with applications of Scotch Tape. The initial reaction to CS2 was characterized as local redness and, in some cases, a flare beyond the contact area. Several hours later a chemical burn developed that persisted for 24 h and beyond. With intact skin, exposure time to perceptible redness ranged from 0.5 to 5 h on the lower back and as short as 0.3 min on the face. When the skin on the lower back was stripped with Scotch Tape, time to perceptible redness decreased to 2–20 min. Holland and White (1972) applied 2–30 mg CS under 4 cm watch glasses to volunteers for 1 h. Only at 20 mg did they find faint redness during exposure, disappearing after exposure stopped. When moistened with water, faint redness was seen with 10 mg or more lasting for 1–2 days. There was no blistering. Punte et al. (1963) exposed volunteers to 24 h patch testing to CS as a dry powder. They found that CS was a severe skin irritant. In 5/11 exposed under occlusive dressings, vesicle formation with redness and sloughing occurred. With a porous cover, 4/4 had vesicle formation surrounded by redness. Gutentag et al. (1960) exposed human subjects to CS in a wind tunnel at levels of

5 mg/m3. Burning of the skin occurred on exposed surfaces and was greatly accentuated by perspiration, tearing, nasal discharge, or salivation. Burning remained for several hours and recurred upon washing the exposed areas. Hellreich et al. (1967) exposed the arms of volunteers to thermally generated CS at an ambient temperature of 97 F and 100% humidity and a wind velocity of 5 mph. They studied four groups of four volunteers each. Exposure times varied from 15 to 60 min. Stinging began 5–10 min after start of exposure. After exposures, the skin was rinsed with cold water for 1 min. One minute after exposure, patchy vascular dermal redness was noted that persisted for up to 3 h with persistence time related to exposure. At exposure levels of 14,040 and 17,700 mg-min/m3 there was a delayed response beginning from 12 to 24 h after exposure consisting of first and second degree burns with the latter occurring in four of eight volunteers. Epithelialization took place within 10 days. At six weeks, there was mild postinflammatory hyperpigmentation. Healing of minor wounds was not affected by the CS burns. Hellreich et al. (1969) exposed 28 volunteers by means of a plastic sleeve and removable patches to CS thermally generated from M7 grenades and maintained at a


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concentration of 300 mg/m3. Patches were removed to give Ct exposures ranging from 1515 to 33120 mg.min/m3. At 20C and 95% RH, four subjects developed minimal delayed redness at CS exposures of 26,025–30,240 mg-min/m3. In contrast under tropical conditions delayed redness occurred at CS exposures of 3,500 mg-min/m3 and vesicular rashes occurred at exposures of 3,030 mg-min/m3. The mean effective dose for redness (MED50) was 3,500 1,500 mg-min/m3. The lowest effective dose for redness was 1,515 mg-min/m3 for exposures under tropical conditions and 21,060 mg-min/m3 for exposures under temperate conditions.

11.3.7 Sensitization Marzulli and Maibach (1974) used human subjects to test for the sensitization ability of CS. Ten chemical insults were delivered to skin in over 3–5 weeks followed by a two-week rest than a challenge contact CS (0.5 gm of 1% CS) was applied to the upper arm under occlusive dressing for 48 or 72 h with each contact. Challenge was done with a nonirritating concentrations. Five of the nine subjects reacted to a 1% challenge, 1/9 to a 0.1% concentration and none to a 0.01% concentration. The data were regarded as showing that CS is a strong sensitizer.

11.3.8 Acute persistent – eye Parneix-Spake et al. (1993) reported on 11 patients who were hospitalized with bullous dermatitis after self-defense spray exposures to a product containing 5% CS. Keratitis was identified in three of nine patients who had eye examinations.

11.3.9 Acute persistent – inhalation Inhalation of CS can result in inflammation of the airways and damage to the lung. CS is used for building entry maneuvers. Its use in enclosed spaces can result in very high exposures. Risk of adverse effects is a function of dose (Ct): if someone cannot leave the structure quickly, then there is an increased risk of chest effects. Acute airway inflammation can lead to chronic airway inflammation with associated reactive airways dysfunction syndrome (RADS). This condition has occurred after exposures to CS aerosols in enclosed spaces and to personal defense sprays. Himsworth et al. (1969) note that a number of asthma attacks were associated with use of CS grenades and shells for crowd control. A child had an asthma attack some hours after being exposed to CS while playing with spent shell. The asthma attack cleared in 12 h. Six cases were sent to a hospital: Three were admitted and rapidly recovered. The other three had largely cleared by the time they reached hospital. In another case where an individual with a history of asthma and bronchitis was exposed to CS, deterioration in pulmonary function tests was found. Himsworth et al. (1971) revisited the area several months later and described a case where a man was struck in his chest by a CS tear gas canister. He developed chest symptoms with signs of bronchitis when seen one month later and persisting for at least nine months. They further report on 10 patients with chronic bronchitis who were exposed to CS in Londonderry and had pulmonary function studies three weeks after exposure and again six months later. There was about a 10% improvement in pulmonary function parameters at six months. Anderson et al. (1996) describe a series of patients who were exposed to large quantities of CS used as a tear gas. Among 184 exposed patients, 21% had shortness of breath and 19% had chest pain. One child complained of shortness of breath lasting for 33 days



after the incident. She had abnormally low peak expiratory flow readings and an history of asthma. Hu et al. (1989) describe the use of large amounts of CS during civil unrest in South Korea. Exposed hospitalized patients with asthma and chronic obstructive pulmonary disease experienced deterioration in lung function and lengthening of stays. Park and Giammona (1972) describe the case of a 4-month-old, who was exposed to CS for 2–3 h when police had fired tear gas canisters into his house. The infant had copious secretions and coughing when removed from the house and was hospitalized. He was found to be wheezing, respiratory distress and hyperinflation on chest X-ray. He was treated successfully for severe bronchoconstriction. He developed a pneumonia on the seventh day in hospital requiring antibiotic treatment. Krapf and Thalmann (1981) describe the case of a 43-year-old male who was heavily exposed to CS tear gas while indoors. A 1 g gas cartridge was ignited as a joke. He had immediate burning pains in his eyes and chest, tearing, shortness of breath, and coughing. When he was seen 1–2 h later in an emergency room he was found to have confluent shadows on chest on X-ray that increased by 6–8 h after exposure, consistent with pulmonary edema. He was cyanotic and had foaming, pink sputum. He was treated for pulmonary edema with little improvement. By four days after exposure he was still cyanotic and developed signs of right heart failure with associated liver dysfunction. He continued to have problems with shortness of breath, chest pain, and liver enzyme changes until at least 49 days after exposure. A complete medical examination conducted three months after exposure showed that all abnormalities had resolved. Hu and Christiani (1992) describe an accidental exposure to CS in a 21-year-old with no prior history of airways disease. A canister of CS was discharged 2–3 m from her in a crowded nightclub. Patrons were unable to escape for 5–10 min. She experienced intense irritation of her eyes, face, throat, nose, and chest. She had coughing, chest tightness, and a burning pain of her chest. Coughing and shortness of breath persisted and were associated with wheezing. Four weeks after exposure her forced expiratory volume in 1 s was 62% of predicted and dropped by 16% with associated wheezing when exercising in cold air. Symptoms continued for next two years and were aggravated by exposures to cold air, tobacco smoke, or automobile fumes, or with exercise. The authors judged that her chest problem was consistent with the diagnosis of RADS. Roth and Franzblau (1996) describe an individual who was exposed to aerosols of CS and OC when lying on a mattress contaminated by a personal defense spray containing 1% CS and 1% OC. Immediate symptoms of cough, chest tightness, and mucous membrane irritation occurred followed shortly by wheezing and shortness of breath. Reversible airways disease was identified on pulmonary function testing. Wheezing was noted on examination four months later and treatment for control of airway reactivity continued for the next three years. There had been no prior history of airways disease. The authors felt that their patient’s findings were consistent with RADS. Hill et al. (2000) describe clinical history of a 30-year-old man who was sprayed with CS indoors in a prison. He developed cough, redness, and swelling of his eyes during the next day. He had worsening chest tightness and shortness of breath over subsequent days. Eight days after exposure he was hospitalized with asthma, icterus, and a patchy pneumonia. He was found to be hypoxemic and allergic to CS on patch testing. During the subsequent months he continued to suffer from a cough and wheezing consistent with RADS. He still had asthma-like symptoms a year later. Himsworth et al. (1971) interviewed a Dr Vennema told the Committee of his experience while in Vietnam from 1965–67. He saw some 20–30 patients who were hospitalized 6–18 h after being heavily exposed to CS. Their ages ranged from 4 to 65 years. On admission these patients were feverish, semicomatose, and extremely short of breath. There were signs of pulmonary edema. About one-half of this group died. A postmortem


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examination in one case showed pulmonary edema. A condition like chronic bronchitis persisted for at least a time in the survivors. The Committee felt that the described deaths were likely to be related to extremely high CS exposures.

11.3.10 Acute persistent – skin Second and third degree chemical burns have been described after exposures to CS both as a tear gas and as a self-defense spray. Cases occurred when CS was used in enclosed spaces, when used in tropical environments, or when there is a delay in decontamination. Prior skin injury (including, injury by prior spraying) can increase the severity of the burn. Zekri et al. (1995) and Anderson et al. (1996) report the effects associated with the use of large quantities of CS tear gas canisters in riot at a Vietnamese detention center in Hong Kong. They initially evaluated 96 individuals with burn injuries associated with CS exposure during that event. Thermal injuries accounted for 83 of the cases. In 13 cases, the burns were secondary to CS exposure. Most of the latter were associated with contaminated clothing. In one 5-year-old boy, there was a 4% chemical burn involving the hand and thigh requiring debridement and skin grafting of the hand. The case records of the 184 patients with symptoms consistent with CS exposure were reviewed two months later. Of these, 52% had burns: 16 had first degree burns, 78 had second degree burns, and 22 with third degree burns. Both exposure in a contained area tropical environmental conditions were likely to have contributed to the frequency and severity of burns. There may have been a delay in decontamination as well. Varma and Holt (2001) describe an allergic dermatitis that developed in an individual who was sprayed with a 5% CS spray while sitting in car. He had been sprayed nine months previously without any skin reaction. A diffuse redness occurred marked by periorbital edema, blistering, and crusting. Parneix-Spake et al. (1993) reported on 11 patients who were hospitalized with bullous dermatitis after CS self-defense spray exposures. Five had previous exposure to CS sprays. All presented with an rednesstous dermatitis localized to areas directly exposed to the spray (face, neck, and hands). The dermatitis began 12 h to 3 days after exposure. In seven cases there was impressive swelling of the face. About 2–13% the body surface was involved with second degree burns with involved areas covered with vesicles, blisters, and crusts. The five patients with previous exposure did not differ from those without prior exposure to CS. Southward (2001) describes an individual who developed a second degree burn of the ear after being sprayed in the face with a CS personal defense spray. One of the authors (WS) evaluated a gentleman who had been sprayed with a personal defense spray containing 1% CS and 1% OC some 4–5 times over a 12-month period. On each occasion he was jailed and did not have an opportunity to decontaminate until his release the next day. He was initially sprayed twice in 24 h. On each occasion he developed a bullous dermatitis involving areas of his face, arms, and trunk that came into contact with the spray. After the blisters broke he would continue to have a crusty rash for 1–2 weeks. An attempt was made to reduplicate the events leading to the recurrent rash. CS/OC spray (77–116 mg) were placed under nonocclusive dressings on the forearm on a volunteer for 11–15 h and then decontaminated with a dilute detergent solution. After a 7 h rest, a second treatment under a nonocclusive patch was made to one of the sites. At the time of removing the patch 15 h later, a blister had formed. Beginning at 24 h after decontamination generalized redness and swelling developed involving an area of 20 times the size of the original patch test. This resolved at 72 h after decontamination. Initial reepithelialization was completed seven days after decontamination. At two weeks



after decontamination, the area remained red and atrophic (scarred) with scarring still apparent six months later. The site where there had been no re-treatment remained red and slightly raised for three days and then resolved without blistering. Although this reaction appears to be a toxic reaction from CS contact to injured skin, recurrent exposures increase the risk of sensitization. Schmutz et al. (1987) note that habitual offenders with repeated exposures to CS sprays can present with acute eczema of the face. Healing can be delayed if there is a secondary infection or reinjury.

11.3.11 Acute persistent – sensitization CS is a strong sensitizer. Skin exposures, either in the laboratory or field, either when exposure has been to a aerosol or spray, have led to allergic contact dermatitis with either prolonged rashes or hypersensitivity to CS with repeated exposures. Hellreich et al. (1969) exposed 28 volunteers by means of a plastic sleeve and removable patches to thermally generated CS aerosol. One of the volunteers developed a classical delayed eczematous hypersensitivity reaction 10 days after a single exposure under tropical conditions to a maximum exposure of 27,540 mg-min/m3. This was the subject’s first exposure and there was no blistering with the exposure. Ro and Lee (1991) describe a male who developed contact dermatitis beginning one day after walking through a cloud of CS riot gas. He had had several exposures to CS during the preceding year. A vesicular eruption was noted and patch tests were positive to CS at 10 ppm with a vesicular eruption at the site of the test but negative at 2 ppm. In a second case, eczema of face and forearms began 4 h after heavy exposure to CS tear gas. The individual had been exposed three weeks before the incident without any rash. Patch testing resulted in a vesicular eruption at 10 ppm CS and a papular reaction at 2 ppm. Fuchs and in der Wiesche (1990) interviewed 56 occasional demonstrators who were exposed repeatedly to CS and/or CN. Of these 59% complained of skin rashes. Allergy testing to 10 ppm CS showed mild reactions in four. Hill et al. (2000) describe clinical history of a 30-year-old man who was sprayed with CS indoors in a prison. He developed a generalized pruritic rash and was found to have an elevated eosinophil count. Patch tests to 1 : 100,000 CS were positive. He suffered a generalized dermatitis for several months after the incident. Sommer and Wilkinson (1999) describe an individual who developed bullous dermatitis seven days after being sprayed by police with a CS spray. He had been exposed once before to CS. A skin biopsy showed spongiotic dermatitis with many eosinophils consistent with an acute allergic contact dermatitis.

11.4 CR Dibenz[b,f]1:4-oxazepine (CR) has been evaluated as a less toxic and more potent replacement for CS since the early 1960s. It has not, however, been used routinely as an RCA. Consequently, information on human effects are limited to studies done during its development as an RCA. There are no reports of sensitization, severe skin, eye or lung effects or long lasting exposure-related problems that occurred during exposure characterizations studies.

11.4.1 Thresholds Ballantyne and Swanston (1974) evaluated CR solution effects in 35 men. They found that the threshold for CR in the human eye to produce blepharospasm averaged


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8.6 107 M and to produce irritation averaged 4.9 107 M. They note that the human eye is considerably more sensitive to CR as an aerosol than as a solution: The TC50 for CR in solution is 9.1 102 mg/L vs 4.0 106 mg/L for CR aerosols in air. The authors suggest an IC50 of 3.3 106 M for CR in humans based on extrapolation. Ballantyne (1977) noted the following irritant concentrations for CR aerosols: an IC50 of 0.7 mg/m3 and IC75 of 1.1 mg/ m3. They found a TC50 for chest irritation of 0.002 mg/m3. Foster and Weston (1986) found that the threshold for pain when CR was applied to a blister base was 5 106 M.

11.4.2 Eye Ballantyne et al. (1976) drenched men and women subjects with solutions of 0.0010% and 0.0025% CR. Drenching occurred either via a six-headed shower or with a dense spray for up to 1 min until subjects were soaked. There was immediate eye discomfort with blepharospasm and profuse tearing. Within 5–6 min after exposure, subjects could open their eyes. Ballantyne et al. (1973) exposed more than 150 male volunteers to 0.01 or 0.1% CR in a solution made up of equal parts of water and PEG 300 via splashing. Exposures were associated with intense eye irritation, eye pain, blepharospasm tearing, conjunctival injection and minimal edema of the eyelids. Effects persisted for at least 15–20 min. Blepharospasm and tearing usually cleared in 30 min while edema persisted for 6 h. There was a short-lasting small rise in intraocular pressures.

11.4.3 Inhalation Ballantyne et al. (1973) exposed more than 150 male volunteers to 0.01% or 0.1% CR in a solution made up of equal parts of water and PEG 300 via splashing. There was a burning sensation in the mouth associated with considerable salivation, mild irritation of the nose, nasal stuffiness, and nasal discharge, all of short duration. Within 5–6 min after exposure, subjects could open their eyes. Ashton et al. (1977) exposed human subjects to a 1–2 m CR aerosol for 1 h at 0.25 mg/m3. Peak expiratory flow was found to decrease by 7% after 20 min of exposure. There was a transient increase in heart rate. The authors postulated that CR stimulated pulmonary irritant receptors to produce bronchoconstriction. The National Research Council (1984) described effects on human subjects tested at Edgewood arsenal: Between 1963 and 1972, 33 subjects were exposed to aerosols of CR ranging from 0.01 to 34 mg-min/m3. All effects were transient and included upper airway irritation; choking, shortness of breath, and rapid breathing; and eye irritation, blepharospasm, and tearing.

11.4.4 Skin CR has been tested for its ability to cause skin irritation at concentrations ranging from 1 ppm to 1%. A 1 ppm CR causes pain in the blister base model, equivalent to contact with abraded skin. In intact skin pain and redness occur at 10 ppm. Concentrations as high as 1% in liquid or 25 mg as a solid cause skin pain and redness without chemical burns, delayed effects or sensitization. Foster and Weston (1986) evaluated CR using the human blister base model. They applied 0.04 mL of various concentrations to a blister base and graded pain response after



1 min of contact. Both pain and desensitization with repeated exposures occurred with 5 M CR (1 ppm). Chemical burns or sensitization do not occur at concentrations as high as 1%. Ballantyne et al. (1976) drenched men and women subjects with solutions of 0.0010% and 0.0025% CR (0.05–1.3 mM). There was immediate intense stinging and redness of the skin. The skin irritation was associated with a rise in blood pressure. Peak blood pressure rise was 30–80 mmHg systolic, and 15–45 mmHg diastolic occurring 1–3 min after drenching and thereafter slowly declining, returning to normal in 2–15 min. One group was tested with submaximal exercise starting 2 min after drenching (time enough to allow pain to develop). Exercising did not result in further increases in blood pressure. Skin sensations were considered mild or had disappeared within 20 min of exposure. Ballantyne et al. (1973) exposed more than 150 male volunteers to 0.01% or 0.1% CR via splashing. There was burning pain of the skin lasting 15–30 min with the sensation readily reactivated if the area is moistened, even after several days. Intense skin redness occurred corresponding exactly to the area of skin contamination. The redness persisted for several hours. There were no vesicles or sensitization. There were increases in blood pressure and pulse changes thought secondary to discomfort and apprehension with increases of 5–100 mmHg systolic and 0–40 mmHg diastolic pressure, usually returning to normal within 30 min. The heart rate would decrease as much as by 25% at the time the blood pressure was elevated, usually returning to normal in 5 min. Weigand and Mershon (1970b) patch tested 39 subjects in various anatomical sites to concentrations of CR ranging from 0.01% to 1% for exposure times of 5–30 min. Ambient temperatures ranged from 18.3C to 25.6C. Onset of skin symptoms was faster at higher temperatures. Transient redness was seen that subsided in 2–4 h. The National Research Council (1984) described effects on human subjects tested at Edgewood arsenal. Between 1963 and 1972, 64 subjects received skin exposures. Test concentrations ranged from 0.1% to 1% with application times of 5 or 30 min. CR was used as a face spray from 3 to 12 feet away in a wind tunnel in subjects wearing goggles. All effects were transient. With patch testing there was stinging and redness resolving within 24 h. Redness developed only on contaminated skin. Contact was not associated with either blistering or sensitization. Holland (1974) applied 0.5–25 mg of CR as a dry powder or moistened with saline to the skin of volunteers. The powder was washed off in 1 h. All reactions were transient and mild if powder was dry, with redness noted at 2 mg but not at 0.5 or 1 mg. If moist, reactions to CR, both as irritation and redness, were first noted in all subjects at 1 mg but even at 10–25 mg were only moderate. Redness disappeared 30 min after decontamination. No blistering or sensitization occurred. When the affected areas were washed at a later time, even up to 24 h later, recurrent irritation was noted.

11.5 CAPSAICIN Capsaicin, along with dihydrocapsaicin, is responsible for the “heat” sensations noted with skin contact or ingestion of products containing capsaicinoids. It is available commercially as a pure chemical but has not been developed as an RCA.

11.5.1 Thresholds Threshold effects have been observed in man for exposures to either capsaicin or capsaicinoid-containing powders. These effects are summarized in the Table 11.3 and discussed in greater detail later in this chapter or in Chapter 14 on Occupational exposures.


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TABLE 11.3 Threshold effects seen with capsaicin or capsaicinoid exposures Effect

Exposure concentration

Type of exposure

Reference

Bronchoconstriction Bronchoconstriction in asthmatics Cough Cough with sensory hyperreactivity Nose irritation Nose irritation Chest symptoms

5 106 M

Capsaicin

Fujimura et al. (1993)

1 106 M 6 106 M

Capsaicin Capsaicin

Hathaway et al. (1993) Fujimura et al. (1992)

1 106 M 4 g/m3 2 105 M 0.3 g/m3

Capsaicin Capsaicinoids Capsaicin Respirable capsaicinoids

Millqvist (2000) Chan et al. (1990) Sanico et al. (1997) Lankatilake and Uragoda (1993)

Although thresholds for eye effects to capsaicin have not been determined, an irritant concentration has been identified in experimental animals. Jancso et al. (1968) instilled 50 g/L (1.6 107 M) of capsaicin into rat eyes. This evoked a violent pain reflex and blepharospasm as well as extravasation as demonstrated by Evans blue dye. Chan et al. (1990) evaluated 61 male spice grinders exposed to chili pepper dust. Upper airway symptoms were experienced in 49%. Dust levels ranged from 0.03 to 0.82 mg/m3, with a mean value of 0.15 mg/m3. Assuming 0.50% capsaicinoid content of the pepper dust, dust exposures would be equivalent to a mean of 0.8 g/m3 capsaicinoids with a maximum of 4 g/m3. Lankatilake and Uragoda (1993) evaluated the respiratory function of 15 workers exposed to chili powder. When first employed, 60% of workers experienced chest symptoms and 44% developed chronic chest symptoms. The capsaicin content of the chili was 0.25% and average respirable dust levels was 0.06 mg/m3. Assuming that the capsaicinoid content of the chili powder was twice that of the capsaicin content, then exposures to capsaicinoids would have averaged to 0.3 g/m3.

11.5.2 Inhalation Nose effects Capsaicin is used for treating vasomotor rhinitis. Amounts as small as 250 pg can cause nose symptoms and 15 g produces overt pain. With repeated applications, the nasal mucosa becomes desensitized and produces long lasting decreases in nasal stuffiness and nasal discharge in patients with chronic rhinitis. Intranasal doses of capsaicin as high as 100 g have been used. The highest concentration used in these various studies, 1 mM or 0.03%, is a factor of 40 less concentrated than the capsaicinoid content of some OC selfdefense sprays (Reilly et al., 2001). Bascom et al. (1991) investigated nasal responsiveness to capsaicin in individuals with environmental tobacco smoke (ETS)-related rhinitis. The authors challenged 10 ETSsensitive and 11 ETS-nonsensitive subjects intranasally to 25 pg – 25 ng of capsaicin in 25 mg of lactose. Subjects rated nasal symptoms and underwent nasal lavage. A dose of 250 pg capsaicin (3.2 109 mol/kg of lactose) was associated with a significant increase in burning, sneezing, and nasal discharge. At a dose of 2.5 ng of capsaicin (3.2 108 mol/kg of lactose) there was increased nasal congestion as well.



Sanico et al. (1997) exposed 10 subjects with active allergic rhinitis to capsaicin administered by means of nasal spray in doses of 1, 10 and 100 g (2, 20, and 200 M) in a double-blind, randomized, crossover manner with one week between doses. Nasal lavage was performed before and at 30 min, 1 h, and 4 h after capsaicin challenges. Symptoms associated with the challenges included burning, congestion, and nasal discharge. Leukocyte counts or albumin and lysozyme levels were not significantly increased after administration of 1 g of capsaicin but were increased after 10 and 100 g of capsaicin up to 4 h after exposure.

Inhaled nebulized capsaicin Cough sensitivity has been evaluated using capsaicin inhalation as a model and diagnostic tool. Normal subjects cough after inhaling 5–6 106 M capsaicin. Using exposures of 2 M of capsaicin or less, researchers have found that patients with sinobronchial syndrome and atopy with allergies in inhaled antigens (Fujimura et al., 1992, 1998). There are, however, several conditions where there is increased cough sensitivity to capsaicin compared with normal subjects including sensory hyperreactivity, asthma, cough-variant asthma, viral chest infections, and chronic obstructive lung disease (Fuller, 1991; Millqvist, 2000; Millqvist et al., 2000; Doherty et al., 2000; Cho et al., 2002). Exposures to capsaicin in the range of 5106–2.5103 M can cause bronchoconstriction with increased airways resistance during the first minute after exposure. Studies done from 1–9 min after exposure to capsaicin at these levels have not shown evidence of continuing bronchoconstriction (Collier and Fuller, 1984; Fuller et al., 1988; Choudry et al., 1990; Nichol et al., 1990; Fujimura et al., 1993). The likelihood of bronchoconstriction occurring with capsaicin inhalation appears to increase with dose. Even the highest exposure concentrations used in these studies was 0.07%, a factor of 20-fold lower than the level of capsaicinoids found in some personal defense sprays (Reilly et al., 2001). Hathaway et al. (1993) studied the effects on air flow, measured as forced expiratory volume in 1 s (FEV1) of inhaled capsaicin in concentrations of 3 106–0.3 mg/mL and methacholine (1–16 mg/mL) in 10 normal subjects and 17 asthmatic subjects. Capsaicin had an immediate irritant effect on the airways in some asthmatics producing bronchoconstriction 10 s after inhalation. Capsaicin doses of 0.003–0.3 mg/mL (1 1061 103 M) gave similar response as seen with 1–16 mg/mL methacholine. Seven asthmatic subjects developed bronchoconstriction after capsaicin (fall in FEV1 of 5.6–40.4%); the remaining 10 asthmatic subjects showed no response. Those asthmatics with greater methacholine responsiveness tended to have greater bronchoconstriction with capsaicin: of seven responders only one was not responsive to methacholine; of 12 methacholine responders, six were responsive to capsaicin. All normal subjects were nonresponsive. All subjects coughed with capsaicin inhalation. Fuller et al. (1985) studied the effect of inhaled capsaicin on airway tone in human subjects. They found that inhaled capsaicin at concentrations of 105 and 104 M (doses of 0.24 and 2.4 nmol, 0.07 and 0.7 g) caused a dose-dependent fall in specific airways conductance (maximum fall 28% and 38%, respectively). This change was maximal within 20 s of exposure and lasted for less than 60 s. There was no difference in the magnitude or duration of bronchoconstriction between normal, smoking, or asthmatic subjects. On repeated exposure to capsaicin, there was no evidence for a reduced response (tachyphylaxis) in both normals and asthmatics.

11.5.3 Ingestion Desai et al. (1976) studied the effects of intragastic infusion of 5, 7.5, and 10 mg/h capsaicin in 28 normal human subjects. They found a significant increase in the DNA


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content of gastric aspirate at highest dosage, a measure of exfoliation of gastric epithelial cells.

11.5.4 Skin Buck and Burks (1986) describe the skin application of 1% capsaicin solutions to human subjects. Treatment produced a burning sensation and a widespread flare response. They noted that treatment with capsaicin abolishes histamine-induced flare and itching but not weal. Treatment blocked skin reactions in patients with heat or cold-induced urticaria. Carpenter and Lynn (1981) applied 1% capsaicin painted on human skin of six volunteers at of intervals 2 h. Several applications resulted in a decreased heat threshold by 3.5C, for 0.4–10 h following application, presumably because of irritation, and then an increase in heat threshold by 2C for 2–10 days with a gradual return to normal over next few weeks. Substance P was injected into treated and control skin areas in three subjects. Capsaicin greatly reduced or eliminated the flare response but not edema. Foster and Weston (1986) studied the effects of capsaicin using the human blister base model. A capsaicin solution of 0.04 mL was applied to a blister base and reactions compared to other lacrimators. Applications frequently produced a flare around the blister and the degree of flare correlated with applied concentration and pain. Capsaicin resulted in pain at 0.5 mol/L (0.5 M or 153 g/L or 0.006 g). Pain at 2 min was similar for all applications but at time zero pain for VAN 50 M CS 100 M CR 5 M 0.5 M capsaicin 0.1% ethanol (vehicle control).

11.5.5 Acute persistent – sensitization Meneghini and Angelini (1979) describe a 37-year-old patient who applied a 0.5% capsaicin cream as an antirheumatic agent to the right foot. After several days an allergic contact dermatitis developed involving the foot and lower leg. Patch tests to the cream and 0.5% capsaicin in petrolatum were positive.

11.6 OC Oleoresin capsicum (OC) contains natural capsaicinoids in concentrations of 0.08–13.1% with capsaicin and dihydrocapsaicin making up 74–84% of the total capsaicinoids (Reilly et al., 2001). The level of capsaicinoids in OC spray products ranges from 0.1% to 1.3%. Unlike exposures to respirable aerosols generated in an exposure chamber, the respirable content of these sprays can be as low as 0.0001% (Dubay and Rush, 1998). Personal defense sprays come in various configurations. Those that have a contiguous stream or cone spray pattern act as liquids when they contact surfaces (Stopford, unpublished data). When sprayed directly into the mouth, aspiration of this liquid may be a concern (Billmire et al., 1996; Winograd, 1977).

11.6.1 Eye Lee et al. (1996) evaluated Snellen visual acuities and anterior segment appearances of the eyes of 22 police officers and after being sprayed with an OC self-defense spray that used isopropanol as a solvent. All officers experienced intense blepharospasm, tearing, conjunctivitis, and incapacitation as the result of spray exposure. Acute effects lasted for about 5–10 min, with relatively complete recovery occurring in about 30–60 min. All had



significant conjunctivitis, and some had water-drop-shaped corneal defects that stained with fluorescein. These defects resolved within 24 h without treatment. The authors examined the corneas of eyes of 13 additional policemen before and after being sprayed with a 5% OC personal defense spray containing isopropanol as a solvent. Injection resolved in 60 min. Visual acuity was unchanged. The corneas of 10/13 officers were normal. Three subjects sprayed with burst nozzles (high volume) showed several 1–2 mm circular areas of superficial epithelial loss that stained with fluorescein. These resolved in 24 h. A third group of nine officers was evaluated after being sprayed with an inert burst spray containing methyl salicylate and isopropanol as a solvent. Eight of nine officers had superficial epithelial defects of their corneas. This trial was immediately followed by being sprayed with the OC/isopropanol spray. No additional corneal defects or effects were identified in these eight officers. But the ninth developed corneal defects. All defects resolved in 24 h. The authors felt that the corneal epithelial erosions may have been secondary to the isopropanol carrier which is quite toxic to corneal epithelial cells. Vesaluoma et al. (2000) evaluated 10 police officers before and after being sprayed with OC spray. The authors measured corneal sensitivity and examined corneas microscopically. The subjects were examined before application and 30 min, one day, one week, and one month after OC exposure. OC spray produced occasional areas of focal epithelial defects that healed within one day. A microscopic examination of the corneas showed swelling of epithelial cells but no other abnormalities. Visual acuity did not change with exposures. Mechanical sensitivity remained below normal values for seven days. Chemical sensitivity to CO2 was high for as much as one day and decreased below normal one week later. Sensitivity to cold was unaffected. Zollman et al. (2000) examined the eyes of 47 officers before and at 10 min and 1 h after exposure to OC spray during a training exercise. Eleven subjects were reexamined at one week after exposure. The examination included tests of visual acuity and corneal sensitivity and a slit lamp with fluorescein staining. Visual acuity was unaffected but corneal sensitivity was reduced at 1 h after exposure. In 21% of eyes, there was evidence of punctate epithelial erosions, but no corneal abrasions were found. All subjects reported significant pain, blurring of vision, and tearing at 10 min that was much improved by 1 h after exposure. At one week after exposure, corneal sensation returned to baseline and no corneal abnormalities were found.

11.6.2 Inhalation Chan et al. (2002) exposed 35 subjects (24 men and 10 women, ages 22–46) to OC or placebo spray and evaluated measures of bronchoconstriction. Spirometry, oximetry, and end-tidal CO2 levels were collected at baseline and throughout the 10 min following exposure. The OC spray contained 0.92% capsaicinoids. Subjects were sprayed for 1 s while their heads were in a 5 3 3 box with subject’s being 5 from the canister. If the spray was fully dispersed, subjects would have been exposed to 13 mg/m3 of capsaicinoids. Each subject’s head stayed in the box for 5 s after being sprayed. OC spray exposure did not result in abnormal spirometry, hypoxemia, or hypoventilation when compared to placebo in either sitting or prone positions.

11.6.3 Ingestion Myers et al. (1987) gave healthy subjects test meals containing red pepper (0.1–1.5 g) in a double-blind fashion. Serial gastric washes were performed after the test meal. Dosing was


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associated with increases in acid and pepsin secretion and in potassium loss. Gastric cell exfoliation (as reflected in DNA loss into gastric contents) was increased. Mucosal microbleeding was seen and one subject had grossly visible gastric bleeding. Aspirin ingestion was comparable in effects to the higher doses of red pepper. Tominack and Spyker (1987) describe three children of ages 3, 5, and 7 who were repeatedly disciplined over a period of months by placing a split jalapeno pepper or tobasco sauce in the their mouths for 15–20 min. Abuse was associated with burning of the mouth, throat, stomach, and, in some instances, anus. Vomiting and diarrhea occurred after some mistreatments. Viranuvatti et al. (1972) studied 20 normal subjects where they instilled a 3% capsicum solution intragastrically and observed for at least 15 min. Treatment was associated with redness, edema, and hemorrhagic spots within 2 min. Abnormalities were seen in seven, with hemorrhagic spots in four, and a severe reaction with progressive hemorrhage and hematemesis in one. Agarwal et al. (2002) evaluated the effects of chili powder ingestion in 29 men with irritable bowel syndrome and compared the results to those of 21 healthy controls. Small bowel transit time was measured after ingesting 10 g red chili powder (capsaicin equivalent 14 mg). Chili ingestion did not alter small bowel transit time. Ketusinh et al. (1966) extracted 10 gm of dried Capsicum minimum chili peppers with 100 mL water then diluted 1.5 : 100 to make a test solution. One drop of undiluted solution was pungent to trained testers. Each of four subjects was given 50 mL of test solution. Treatment was associated with an increase in free stomach acid.

11.6.4 Skin Jones et al. (1987) notes that in New Mexico, chili peppers (Capsicum annuum) are prepared by roasting and manually removing the skin. Peeling is often done barehanded and may cause prolonged burning pain, irritation, and redness but not vesiculation. Twenty female subjects immersed their hands in a standardized slurry of green chili for 40 min. Exposures duplicated symptoms that subjects described associated with peeling peppers.

11.6.5 Acute persistent – eye Brown et al. (2000) reviewed a physician-maintained log of patients presenting to a jail ward emergency area over a three-year period. The standard of care required corneal examination with fluorescein staining. Scleral injection was identified in 38 and corneal abrasions in 7 of 100 cases of where a 10% OC spray exposure had occurred. Watson et al. (1996) describe the evaluation of 81 consecutive patients who presented to an emergency department after OC spray exposure from law-enforcement action over a three-year period. The 81 patients represented about 10% of all those being sprayed during this interval. Corneal abrasions and respiratory symptoms occurred in seven (8.6%) and six patients, respectively. None required hospitalization. A history of asthma was found in 12 of 81 patients but respiratory symptom frequency and severity in asthmatics was similar to respiratory symptoms in those without such a history.

11.6.6 Acute persistent – inhalation Billmire et al. (1996) describe a four-week-old infant who was sprayed accidentally with 5% OC spray. There was rapid onset of gasping respirations and epistaxis followed by respiratory arrest and cyanosis. The infant was supported by mouth to mouth breathing



for 20 min and then intubated. He required high peak inflating pressures and peak end expiratory pressure to achieve adequate chest movement. He had worsening hypoxemia and hypotension requiring pressor agents to maintain blood pressure. Increased airway secretions were noted and a chest X-ray showed bilateral diffuse infiltrates consistent with noncardiogenic pulmonary edema. A secondary chest infection developed by the second day requiring antibiotic treatment. Four days after injury he was placed on extracorporeal membrane oxygenation. This latter treatment continued for 138 h until his lungs recovered. He was discharged nine days after injury with continued treatment with cromolyn and albuterol aerosols. Over the ensuing 12 months he had three additional admissions for viral respiratory infections associated with wheezing. Winograd (1977) described an 11-year-old boy with developed acute respiratory distress 2 h after intentional deep inhalation of several breaths of OC spray. Respiratory arrest occurred requiring mouth to mouth resuscitation. He was found to have stridor, an indication of upper airway obstruction with marked subglottic narrowing on X-ray. He had bilateral perihilar infiltrates worsening 6 h after admission. Initially there was poor air exchange with gasping respiration. There was marked improvement after the insertion of nasotracheal tube 3 h after admission. Treatment included systemic glucocorticosteroids. The authors ascribe the findings to tracheitis, laryngeal edema, and pulmonary edema. There was complete clearing of chest on the second day, substantiating diagnosis of pulmonary edema. He was discharged four days after admission. Follow up evaluations at one week and 10 months after discharge showed no sequalae. Roth and Franzblau (1996) describe an individual who was sprayed with a self-defense spray containing 1% CS and 1% OC. The person was exposed to high levels for at least 30 s from lying on contaminated mattress. Immediate symptoms included cough, chest tightness, and mucous membrane irritation followed by wheezing and shortness of breath. A medical evaluation found reversible airways obstruction on pulmonary function testing. Wheezing was noted when the subject was examined four months later. After an additional three years several medications were still required to control airway reactivity. The individual was restricted by physicians from any further irritant exposures. The authors felt that this individual met the criteria for the diagnosis of RADS. Steffee et al. (1995) describe a case of in-custody death ascribed to the excessive use of OC spray. The subject was sprayed 10–15 times with OC spray while being hogtied. He complained of shortness of breath and experienced labored breathing while in upright sitting position. He became quiet before arrival to the police station and was found to be unresponsive. Resuscitation efforts were unsuccessful. At autopsy the lungs showed florid bronchitis and bronchiolitis, pulmonary edema, and acute aspiration. There was mild laryngeal edema. The authors felt that this individual had bronchospasm secondary to OC inhalation. The American Civil Liberties Union (ACLU, 1995) investigated 26 deaths in California where OC spray was used during arrests. All of these individuals were combative but only two were intoxicated. In all cases the OC spray was ineffective. Drugs or alcohol were felt to be involved in 24/26 of the deaths; 61% had underlying heart or respiratory disease including two who had asthma. Lethal drug levels were found in six cases. Four were noted to have difficulty in breathing after being sprayed and before respiratory arrest including one asthmatic and one with chronic bronchitis. Five had coronary artery disease or an enlarged heart.

11.6.7 Acute persistent – skin Dooley and Dooley (1996) describe a patient who developed painful paresthesias of the hands occurring after eating Cajun-spiced craw fish on two different occasions.


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The examination was normal and symptoms resolved in 24 h on each occasion. Cayenne pepper containing capsaicin is used in Cajun spice. Weinberg (1981) describe a gentleman who abraded the skin of his fingers while sanding furniture. He then prepared a Chinese lunch containing red peppers (Capsicum japonicum). He noted the sudden onset of burning of his fingertips with the burning not relieved by ice water. The pain radiated up his arms and was associated with dizziness and sense of flushing. On examination his face was flushed and red and he was perspiring profusely. He was treated successfully with a local anesthetic gel (lidocaine). These self-limiting reactions are mirrored by “Hunan hand” with chili pepper content in the work place (see Chapter 14 on Occupational exposures). Greer et al. (1993) describe a 66-year-old man presented with a five-day history of arthralgias, fever, painful rednesstous papules, plaques, pustules, and hemorrhagic bullae on both hands beginning several days after picking fifteen quarts of jalapeño peppers. A skin biopsy disclosed pathologic findings characteristic of acute febrile neutrophilic dermatosis or Sweet’s syndrome. The patient was treated conservatively with gradual resolution over the next three weeks. There was reaction to patch testing with 0.25% capsaicin.

11.6.8 Acute persistent – sensitization Gallo et al. (1997) describe a 23-year old individual who developed eczema then asthma after handling latex gloves. Episodes of asthma and epiglottal edema also occurred when eating yellow pepper and prick tests to this antigen were positive. The authors view this as a case of cross sensitization. Raccagni et al. (1995) describe a patient who developed target like lesions, vesicles and small bullae at the site of topical application of a homemade, concentrated alcoholic tincture of capsicum used for its antirheumatic properties. The rash spread to the arms and face some days later. A skin biopsy showed spongiosis and lymphomononuclear perivascular infiltration of the dermis. Patch testing one month later showed positive results to a tincture of the whole pepper plant and peel. Twenty control subjects patch tested to these tinctures had negative reactions.

11.6.9 Acute persistent – ingestion Landau et al. (1992) treated a 25-year-old man who ate 25 chili peppers in 12 min. Epigastric pain began 2 h later. On examination in the emergency room there was evidence of peritonitis and perforation was evident on X-ray. A small duodenal perforation was identified on exploratory laporotomy. The authors postulate that the perforation was related to direct irritation by capsaicin.

11.7 VAN N-nonanoyl vanillylamide (VAN) is a food flavor (at levels up to 10 ppm) and as a rubifactant used in some skin balms. It is used in the personal defense sprays used by police organizations in at least four countries (Independent Commission on Policing for Northern Ireland, 2001).

11.7.1 Skin Foster and Weston (1986) studied the effects of VAN in a human blister base model and compared results to effects seen with other lacrimators. Each test solution (0.04 mL) was



placed on a fresh blister base and pain intensity recorded. Pain at 2 min after application was similar for applications of all lacrimators but at time zero pain for VAN 50 M CS 100 M CR 5 M 0.5 M capsaicin 0.1% ethanol (the vehicle control). Desensitization occurred with repeated applications of 50 M VAN. The flare response to VAN correlated with both pain and concentration.

11.7.2 Inhalation Committee on Toxicology of Chemicals in Food (2002) describe 10 normal subjects and 10 individuals with mild asthma who were exposed to 0.3% and 0.1% PAVA in a 50% aqueous ethanol solution by nebulizer. Exposures per breath were likely at 60 and 200 g of respirable PAVA. In normal subject exposure was associated with a transient cough, a 1% decrease in FEV1, 15% increase in mean heart rate and an 8% increase in mean systolic blood pressure. In asthmatics there was a 3% reduction in FEV1, a 5% increase in heart rate and a 5% increase in mean systolic blood pressure. In two asthmatics with higher levels of nonspecific airway reactivity as indicated by greater methacholine responsiveness, there was transient but clinically significant bronchospasm with drop in FEV1 of 0.5 L. It was judged that this spray would be unlikely to have any significant respiratory effect in normal individuals though some bronchospasm could be induced in asthmatics.

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CHAPTER

Forensic Aspects of Riot Control Agents

12

BRYAN BALLANTYNE1 AND HARRY SALEM2 1 Formerly, Director of Applied Toxicology, Union Carbide Corporation, Connecticut, USA; Senior Medical Officer and Head, Section of Toxicology and Pathology, Chemical Defence Establishment, Porton Down, UK; Adjunct Professor, Pharmacology and Toxicology, West Virginia University, USA 2 Chief Scientist, Research and Technology Directorate, US Army, Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland, USA

12.1 INTRODUCTION 12.1.1 Historical aspects and generalizations Chemicals, mainly in the form of vapors and smokes, have been used by man from early times for protective (by incapacitating) and offensive purposes (SIPRI, 1971). One of the earliest smokes was a burning mixture of pitch and sulfur (Greek fire) which was thrown at enemies to discourage them by virtue of its irritant effects. Arsenical smoke was used by Hunyadi to defend Belgrade against the Turks in 1456, and soldiers of the Bishop of Munster also used arsenical projectiles in 1672 as a siege weapon against Gronigen. Plutarch is said to have described an action by a Roman general in Spain in which an irritant cloud was used to drive enemy out of concealment in caves. This practice was also used in the late-twentieth century for cave and tunnel denial in Vietnam, and led to strenuous denials that this use of tear gas is chemical warfare in the context of the Geneva protocol. The use of chemicals for civilian peacekeeping operations and riot control has become a notable feature of the twentieth century, and has been associated with occasional instances of injury or death which was directly or indirectly attributable to the agent used. Peacekeeping operations can be defined as planned and coordinated procedures for the control of disturbances involving, or between, members of the civilian population and where the level of violence is such that there could be destruction of private and/or public property, and a risk of injury to, or death of, persons actively participating in the disturbance or who, by chance, are present in the area of the disturbance. The circumstances are very variable and may range from criminal assault by one member of the public on another, a prisoner resisting arrest, to large scale riots. It should be the aim of the security forces to restore order with the minimum of physical violence, and using methods least likely to cause injury or to escalate the situation. Relatively recently it has been a major objective to produce riot control agents (RCA) that have a rapid incapacitating effect even against the most motivated of malefactors, easy to disseminate and decontaminate, have a long shelf life and low cost, but not produce significant adverse


RIOT CONTROL AGENTS

health effects in a heterogeneous population which includes the very young, elderly, or otherwise infirmed (Maynard, 1999). As noted above, the use of chemicals for peacekeeping purposes in civil circumstances has expanded and also been reported widely in the twentieth century. In 1912 in Paris the police used ethylbromoacetate (EBA) grenades to temporarily disable lawless gangs by making use of the irritant effects of the gas on the eyes (Swearengen, 1966). A rapid increase in the use of chemicals for peacekeeping purposes occurred in America in the mid-1920s following a marked increase in both the crime rate and in urban gangster warfare. This led to the manufacture and marketing of anti-riot guns capable of firing tear gas projectiles into rioting crowds, or into buildings as a means of evicting armed besieged criminals. About this time, small tear gas pen guns became available for general use in the United States for general self-protection use. Later, around the mid-1950s, an increase in crimes of violence led to a proliferation of tear gas pen gun sales and the development of hand-held liquid irritant spray devices for general sale, although their use is now illegal in many countries. Since the mid-twentieth century the use of chemicals, mainly of an irritant nature, to regain law and order in violent demonstrations has increased, sometimes to large proportions, and on a worldwide scale. For example, during June 1987 political demonstrations in South Korea caused the government to use 351,200 tear gas canisters and grenades against civilian demonstrators (Hu et al., 1989). This was against the lack of information to the Korean medical community on tear gas. The government withheld information on the chemical nature of agents employed, and guidelines were not issued to the public or to health authorities (Hu et al., 1989). Publicity and public outcry against the widespread use of CS (o-chlorobenzylidene malononitrile) in Northern Ireland sectarian riots, led the United Kingdom Secretary of State for the Home Office to appoint a Committee of Enquiry, under the Chairmanship of Sir Harold Himsworth, to investigate the use of CS by the Royal Ulster Constabulary in Londonderry on 13th and 14th August, 1969. A major conclusion of the Himsworth Committee was that despite the extreme discomfort following exposure to CS smoke it is only under exceptional circumstances that exposure doses of CS could be received that might result in serious injury or death. The Committee also made a recommendation that when chemical agents are used for civil purposes, the effects of such agents should be studied more akin to that of a new drug rather than a weapon (HMSO, 1969, 1971). Most countries draw a distinction between agents used for chemical warfare and those used for control of disturbances of the peace in civil situations. In the US such a distinction has been made between chemical warfare agents and military chemicals with the latter excluding chemical warfare agents. The US does not consider RCAs to be chemical weapons as defined in the Geneva Convention of 1925, although there is still some lack in clarification and classification in this respect (White House, 1994; Sidell, 1997; Takafuji and Kok, 1997; NRC, 1999). It is clear from these considerations, and discussed in more detail later, that any disturbance of the peace and its subsequent control by security forces may, in some cases, lead to short-lived ill-health effects, very occasionally to more severe injury or even death. The causes for these effects may be many and varied, and can be associated with factors such as age or prior ill-health. Also, the effects may occur not only in those deliberately participating but also in those who become incidentally involved. Therefore, the potential for injury claims, litigation, coroner’s investigations, claims for the use of excessive and unnecessary force, and police arrests and evidence may be considerable in the event of a moderately large disturbance. Also the approaches adopted by the security forces may lead to enquiries by the “media” and possible questions from political representatives. Thus, against this background there will clearly be a need for consultation and advice from experts in many areas, including those of forensic specialties. This advice


FORENSIC ASPECTS OF RCA

will be needed in respect of the safe use and/or misuse of RCA and the circumstances in which they are used. Additionally, and particularly in planning phases for security operations likely to involve control of disturbances of the peace, there will be a need for expert (including forensic) advice with particular respect to the procedures which may be used and their relative safety. “Forensic” (Latin – forum) implies that the specialty and function has a legal purpose as its basis (i.e. of, or used in courts of law; this may involve local (state), national (federal), and international law. Thus, the work of the forensic expert is performed in the interests of truth (accuracy and integrity) and justice (impartiality). The particular areas of expertise of importance in relation to RCA and circumstances of civil disturbance are those of the forensic pathologist, forensic toxicologist, and forensic psychologist or psychiatrist. The forensic pathologist (medical examiner,) will be medically qualified and have responsibility to assess what was the prime cause of injury or death (natural or induced) of an individual, and whether exposure to a particular material, procedure and/or experience was a contributory factor. In the case of mortality this will mean assessment of autopsy material and the circumstances of the death, and in the case of nonlethal injury will involve a critical examination of case material, including history, physical examination, and the findings from any special investigations. The forensic pathologist needs not only to be familiar with general and forensic pathology, but should be conversant with clinical medicine and have some knowledge of toxicology. He should be prepared for rebuttal arguments from other pathologists and from specialists in various areas of clinical medicine. Most forensic toxicologists are, by education and training, analytical chemists, although there is increasing tendency for additional education and experience in biological subjects. The majority of formal forensic toxicologists are responsible for analytical (chemical) examination of body fluids and tissues, and are experts in these methods, and their sensitivity, specificity, and artifacts. Some will have formal training in formal toxicology which will supplement the advice and consultation given by the forensic pathologist. A major role in defining the contribution of RCA to adverse human health effects comes from the clinical toxicologist, whose contributions will be complementary to those of the forensic pathologist. The forensic psychologist/psychiatrist should be available to give advice on the motivation of malefactors, the possible adverse influence on the success of certain crowd control measures, how best to approach situations of civil disturbance in the context of mixed motivations and variable states of mental health, the social responsibilities of the competent authorities, and tactics in negotiations in planned and spontaneous disturbances of peace. The major functions expected of these various experts is summarized in Section 12.9. The essentials of toxicological and medical aspects of peacekeeping operations is considered in the next section, with particular reference to both the safe use of RCA and peacekeeping procedures, and those aspects of misuse or misplanning that can lead to injuries or even death, sociopolitical repercussions, and possibly litigation.

12.2 AGENTS USED IN PEACEKEEPING OPERATIONS 1

Peripheral sensory irritant (PSI) materials Peripheral sensory irritant materials interact with sensory nerve receptors in skin and mucosal surfaces, producing discomfort or pain at the site of contact together with related local and systemic reflexes. The local reflexes include excess lacrimation and blepharospasm with the eye, and with inhaled materials excess nasal and tracheobronchial secretions, sneezing, coughing, and changes in breathing rate (Ballantyne, 1999). Both the sensations and the local reflexes cause harassment and a desire to vacate the contaminated


RIOT CONTROL AGENTS

2

3

4

5

6

area, and this forms the basis for the use of PSI materials in peacekeeping operations. In view of their effects and usage, they are sometimes referred to as harassing agents or short-term incapacitants. They are the most effective and frequently used chemicals in peacekeeping operations, and thus reviewed in more detail in Section 12.2.1, also refer to Chapter 5. Obscuring smoke cloud agents Although used principally in military situations (Burton et al., 1982; Mishra, 1994) obscuring, or screening, clouds could be used in peacekeeping operations to produce distraction, and obscure potential targets and the security forces. They are disseminated by pyrotechnic generation of the smoke from grenades or canisters. Certain smokes used for military purposes are not appropriate for civilian peacekeeping operations based on toxicity studies in the laboratory demonstrating respiratory tract injury, or since they are known to have caused severe pulmonary injuries or mortality in humans. These include phosphorus pentoxide (Ballantyne, 1998), titanium tetrachloride (Ballantyne, 1982), zinc oxide/hexachloroethane (Marrs et al., 1983, 1988), and zinc chloride smoke (Evans, 1945; Johnson and Stonehill, 1961; Milliken et al., 1963; Hjortso et al., 1988). Smokes of lower acute and repeated inhalation exposure toxicity which might be useful in peacekeeping operations include cinnamic acid (Ballantyne and Clifford, 1978; Marrs et al., 1989), and dyes such as Disperse Red 9, Solvent Green 3, and Solvent Yellow 33, although high concentrations and mixtures of these dyes may result in pulmonary dye retention and foreign body reactions ( Marrs et al., 1984; Sun et al., 1987). Visible and occult markers In solution, these materials may be used to mark and subsequently identify malefactors. For this purpose they may be visible dyestuffs for staining of skin and clothing; this may also cause some discouragement for the lesser motivated to continue participating in a civil disturbance. Clearly, such materials because of their intended persistence need to be carefully chosen, particularly from the point of view of local toxicity. For example, Gentian violet while a very persistent skin staining material, causes severe and prolonged eye damage (Ballantyne et al., 1973a). Occult markers include substances which are colorless but can be detected by fluorescence under ultraviolet radiation. Solutions of markers may be used against individuals by incorporation in hand-held liquid projection devices or against a larger number of rioters by use in water canon. Malodorous substances The dispersal of malodorous substances, such as amines or mercaptans, has been proposed as a physiological means for causing the less motivated rioters to disperse from an area of civil unrest (Witten et al., 1970). Such materials may be delivered using a frangible missile. The addition of a thickening agent will prolong adhesiveness. Clearly, appropriate methods for decontamination will be required. Low friction polymers It has been suggested that the dispersion of slippery agents in the direction of malefactors would impair their movement and hence make it difficult for them to undertake coordinated activities. However, the use of such materials would have to be carefully weighed against the potential for personal accidents, and also the problems associated with having motorized vehicles in the area. Additionally, the use of such procedures would require that decontamination could be carried out shortly after their use in public places. Centrally acting pharmacological agents It has been proposed that pharmacological agents causing, for example, tranquilization or emesis could be delivered to the most violent malefactors and ringleaders using drug-injecting dart guns (Swearengen, 1966; Conner, 1967; Security Planning Corporation, 1972; Deane-Drummond, 1975). Clearly this would necessitate having security forces trained in the use of such weapons, in order to avoid serious accidents.



12.2.1 On the nature and effects of PSI materials As noted above PSI molecules interact with sensory nerve receptors in skin and mucosal surface causing local sensations and local and systemic reflexes. In the eyes the local effects are discomfort or pain with blepharospasm and excess lacrimation. Contamination of the nasal mucosa causes discomfort with rhinorrhea, and of the mouth causes stinging sensations with excess salivation. Inhalation of PSI materials causes stinging, discomfort or pain in the chest with a sensation of tightness, coughing, sneezing, increased tracheobronchial secretions, difficulty with breathing and periods of voluntary breath holding. From a biological point of view these effects are bioprotective in nature, warning of the presence of an irritant material and also limiting exposure to that material. Clearly all these effects are also harassing, which make the affected individual want to vacate the contaminated area, and are detrimental to the performance of coordinated activities; these form the basis for the use of PSI materials in peacekeeping operations. Sensory irritant effects are usually experienced at concentrations significantly lower than those likely to produce adverse effects (toxicity) by acute exposure. This differential in concentration thus limits the potential for exposure to acutely harmful doses of a PSI. In addition to the local reflexes of blepharospasm, cough, sneezing, and increased secretions, there are also systemic reflexes, of which the more important with respect to potential medical considerations are transient hypertension and bradycardia. Sensory irritants, dispersed in the atmosphere, are sometimes referred to (classified as) sternutators having their major actions on the upper respiratory tract, and lacrimators having a principal action on the eye. For most currently used materials, this is not a useful or accurate method of description, since both effects are often present. Exposure to an airborne sensory irritant will result in PSI effects in skin, eye, and respiratory tract. When disseminated in solution the effects are limited to the area contaminated, and the reflexes elicited are a function of the afferent nerve involvement. In general, PSI effects appear within a few seconds of exposure and subside within 10–60 min after the end of exposure. If the incidence of a given response to an exposure to a PSI is plotted as a function of exposure concentration a typical sigmoid curve for a biological phenomenon is obtained (e.g. Figure 12.1). This implies the existence within the population of hypersensitive and hyposensitive individuals, respectively, at the left and right hand sides of the distribution curve, but the majority respond over a relatively small concentration between these extremes. From such frequency distribution data it is possible to calculate median effective concentrations as follows (Ballantyne and Swanston, 1973, 1974). For just-detectable sensation plotted as a function of exposure concentration it is possible to calculate what is a just-detectable sensory response in 50% of the population studies (TC50). This can also be done for incapacitating concentrations; that is those that cannot be voluntarily tolerated (usually for 1 min). Clearly these are concentrations of interest in connection with effective concentrations for peacekeeping operations; as with threshold effects a median effective concentration (IC50) can be calculated, but in the practical context of a riot it may be more meaningful to determine IC75 or IC90 values. The operational effectiveness of a PSI in respect of its use in peacekeeping operations needs to be considered in terms of both the absolute concentration of a specific material and its potency in comparison with established materials. The effectiveness of a given PSI will be a function of both the absolute concentration of material producing an incapacitating effect and the relationship between the incapacitating concentration and the TC50. The closer these values, that is, the smaller the ratio of IC50/TC50 the more rapidly will the incapacitating effects appear within a rising atmospheric concentration of PSI. Thus, the ratio of IC/TC may be referred to as the effectiveness ratio and compared for different materials.


RIOT CONTROL AGENTS

100

Percent response

80

60

40

20

100

200

300

400

[CS] × 10–4 (mg/m3) Figure 12.1: Concentration–response curve for threshold peripheral sensory irritation

to an aerosol of 2-chlorobezylidene malononitrile (CS) based on induced sensation in the human eye. Probit analysis of this data gives a TC50 of 4.0 103 mg/m3 (95% confidence limits 2.3–6.6 103 mg/m3).

TABLE 12.1 Comparison of the peripheral sensory irritant potency of o-chlorobenzylidene malononitrile (CS) and dibenz[b,f]1:4-oxazepine (CR) aerosolsa Material

CS CR CPd

TC50b (mg/m3)

4 103 2 103 2.0

IC50c (mg/m3)

3.6 0.7 5.1

IC75 (mg/m3)

10.0 1.1 9.1

Effectiveness ratio [IC50/TC50]

[IC75/TC50]

900 350

2,500 550

Notes a Data after Ballantyne et al. (1977a). b TC Threshold concentration. c IC Incapacitating concentration. d CP Comparative potency (CR/CS).

Also, the absolute potency of different PSI materials may be compared by examining the ratio of threshold or incapacitating effects at a given level (comparative potency). For example, Table 12.1 compares the PSI materials CS and CR. It can be seen that based on a consideration of the absolute PSI concentrations the relative (comparative) potency of CR is greater than that of CS (at the TC50, IC50, and IC75). CR is more effective than CS



IC84 IC50 IC16

500

200

Dosage (mg/m3)

400 Concentration (mg/m3)

ICt84 ICt50 ICt16

250

300

200

100

150

100

50

0

0 2

4

6

8

10

2

4

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8

10

Exposure time (min) Figure 12.2: Relationship between concentration and time (left hand graph) and

inhalation exposure dosage (Ct) and time (right hand graph) for defined levels of incapacitation (IC – 16%, 50%, and 84%) caused by -chloroacetophenone (CN) aerosol to human volunteers subjects (data after McNamara et al., 1968).

based on a comparison of the effectiveness ratios, which are smaller at both the IC50 and IC75 levels for CR than for CS. The relationship between the exposure concentration of a PSI, [C]e, and the time to onset (latency) of a specific effect is shown in Figure 12.2 (left hand side). For any given [C]e the proportion of the population responding increases with time. This implies that, within limits, that any given degree of incapacitation (e.g. IC50) can be produced by reciprocal relationships between [C]e and exposure time (t)e. Clearly the variability in latency between individuals needs consideration in assessing the effectiveness of a PSI as an RCA. The relationship between (t)e and [C]e also has implications with respect to the total dose of irritant received by the respiratory route, that is, the inhalation exposure dosage [Ct]e, and thus the potential for toxicity. The [Ct]e for given levels of incapacitation are shown as a function of (t)e in Figure 12.2 (right hand side). For a given level of incapacitation, [Ct]e values are larger for the high [C]e – short (t)e conditions than for the low [C]e – high (t)e conditions. Thus, while increasing [C]e shortens the effective response time, it does result in a larger [Ct]e to produce an equipotent harassing effect. Several factors influence the latency to, and potency of, a PSI response. Those of operational significance are as follows: (a)

Concentration As discussed above, and illustrated in Figures 12.1 and 12.2, increasing [C]e will increase the proportion of persons responding, decrease latency, prolong the effect, and produce overall a more potent effect.


RIOT CONTROL AGENTS

(b)

(c)

(d) (e)

Particle size With aerosol dispersions in the atmosphere, the smaller respirable particles (c. 1 m MMAD) cause both ocular and respiratory effects, while larger particles (c. 60 m MMAD) produce predominantly ocular effects (Owens and Punte, 1963). Vehicle With solutions, the use of a surface-active material may enhance spread and penetration of PSI into skin and mucosae, and hence facilitate the irritant response. Environmental conditions Elevated temperature and humidity may decrease tolerance (Punte et al., 1963). Motivation In general, increased motivation and distracting influences will increase the threshold for induction of PSI effects and increase tolerance to suprathreshold concentrations of PSI. This may clearly influence decisions on what constitute appropriate incapacitating concentrations in well motivated malefactors.

Materials currently used in peacekeeping operations in various parts of the world are 10-chloro-5,10-dihydrophenarsazine (DM), -chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS), dibenz[b,f]1:4-oxazepine (CR), and oleoresin capsicum (OC). Details of the physicochemical properties, pharmacology and toxicology of these materials is presented elsewhere in this book, and have been reviewed by Ballantyne (1977, 1987), Busker and van Helden (1998), Marrs et al. (1996), Monsereenusorn et al. (1982) and Salem et al. (2001).

12.3 APPROACHES AND METHODS FOR THE GENERATION AND DISPERSAL OF RCAS In general, RCA for screening purposes are generated by dispersion in the atmosphere; marking agents by dispersion in solution; and PSI materials by both airborne dispersion or projection as coherent liquid jets. The chosen mode of dissemination will depend on specific operational circumstances. Thus, airborne PSI materials may be widely disseminated and result in many individuals being effected, but clearly local meteorological conditions may influence the way in which they are used; for example, with respect to persistence and drift. Solutions of irritants may be projected as coherent jets, and thus used to selectively engage a particular individual or groups of persons. At one end of the operational scale is the use of small hand-held pressurized canisters for use against individuals, and at the other end is the use of water cannon to engage a larger number of individuals. Some specific methods for the generation and dispersion of RCAs are as follows (also refer to Chapter 2). Aerosolization by thermal volatilization The most widely used method for generating a cloud or irritant material or screening smoke from thermostable chemicals is by pyrotechnic. The material is mixed with a base such as chlorate or lactate which, on ignition, causes it to volatilize and subsequently condense into a cloud of solid or supercooled liquid droplets, usually in the range 0.5–2.0 m MMAD (i.e. respirable). Within a short period the suspended particles or droplets settle or aggregate into large agglomerations. On a calm day a typical explosive cartridge or grenade of an irritant will generate a cloud of about 20–30 feet in diameter, which may linger for 10–15 min (Sanford, 1976). The technology of various devices for producing irritant smokes has been described by Swearengen (1966). A variant is to increase the number of burning sources by incorporating subunits into the primary munition, and hence increasing the area over which smoke is generated and with a reduction in the total emission from each subunit. An example is the rubber bursting grenade, which consists of a rubber cylindrical casing packed with small pellets composed of irritant and pyrotechnic composition. Ignition



causes the rubber casing to burst and scatter slowly burning pellets over a wide area, producing a multifocal source of smoke (Ballantyne and Johnson, 1974a). Powder clouds Irritants in fine particulate form can be blown into the atmosphere from a fogging device. For large-scale use with a mobile fogger, the irritant may be mixed with a material such as Neocil for free-flowing properties. On a much smaller scale, ‘tear gas pen guns’ or ‘tear gas pistols’ are available in some countries. These devices contain a small explosive charge which propels and discharges the irritant as a cloud. Tear gas pistols became available to the public in the US in the late 1920s (Rengstorff, 1969a). These devices have a high injury potential. Vapor dispersal Pyrotechnically generated smokes or powder clouds may be unacceptable in some circumstances, For example, when malefactors are in a confined space which has a relatively low ventilation rate, where exposure to smokes may result in asphyxial effects and, as noted later, even mortalities. Also, with grenade generated smokes there may exist the possibility for fires. In order to overcome some of these potential hazards a variety of methods and approaches have been proposed. One of these is the use of highly volatile irritant materials projected into the enclosed area. One such material, 1-methoxycycloheptatriene, although a highly volatile effective PSI was abandoned because of its central neurotoxicity, causing cerebellar Purkinje cell necrosis and gliosis (Marrs et al., 1991). An alternative is the use of an irritant dissolved in a volatile solvent which, when projected into the area by means of an aerosol canister or frangible missile, leaves a vapor or aerosol of the irritant in the atmosphere (Ballantyne, 1979). Solutions Solutions of irritants can be projected as coherent liquid jets, allowing for the engagement of specific targets. Additionally, the use of such solutions also allows the incorporation of marking agents into the liquid for subsequent identification purposes. Using such coherent jets on a small scale avoids or reduces the possibility for kinetic, thermal, and physical injuries. However, with larger scale use of water canon the potential for kinetic injuries is still present, and there is a possibility for physical injury from slipping on the large volumes of liquid projected. With water canon, a PSI can be dissolved in the water at a low concentration to cause skin and eye irritation on drenching, and this avoids some of the potential complications from inhaling grenade generated smokes. A number of hand-held irritant liquid projection devices have been manufactured for use by the security forces, and these have also been sold for self-protection purposes to the general population, although this latter practice is illegal in some countries. These devices are designed to allow the user to direct a spray of the irritant solution at the face of an assailant, thus causing temporary incapacitation from severe eye and facial skin effects which deter the individual and allow the person to be overpowered. In some cases where the irritant is volatile, it is recommended that the spray be directed at the upper body so that vapor is produced and causes harassment by this means. Examples include Chemical Mace and Federal Streamer containing CN, Paralyzer containing CS, and Guardian having OC as the active constituent (Fisher, 1970; Sreenivason and Boese, 1970; Steffee et al., 1995).

12.4 ASSESSMENT OF THE OPERATIONAL USE AND ADVANTAGE OF RIOT CONTROL PROCEDURES IN THE LIGHT OF SAFETY CONSIDERATIONS In assessing the operational usefulness or advantage of riot control chemicals, notably harassing agents, some of the most important factors that need to be considered are


RIOT CONTROL AGENTS

as follows: 1

2

3

4

5

Effectiveness in the intended use Specific factors in assessing the effectiveness and comparative effectiveness of harassing agents (TC50, IC50, effectiveness ratio and comparative potency) have been discussed earlier. General questions on effectiveness arise relating to rapidity of action, potency, persistence of effect, performance against desirability, and the ease by which avoidance and countermeasures can be developed. Most of these require the need for carefully controlled and conducted trials in the laboratory or field in volunteer subjects. Such trials can be combined with biomedical monitors for safety-in-use considerations (see next). Toxicity Toxicology is concerned with determining the potential of a substance (or mixture of substances) to produce adverse biological effects (toxicity); in this context adverse effects are meant to imply those that are detrimental to the normal functioning or survival of the organism (Ballantyne, 1984). If adverse effects are produced it is necessary to know their nature, incidence, mechanism of production, factors influencing their development, and reversibility. The development of a toxicology testing program, considered in more detail later, should take into account that in addition to investigating the toxicity of a specific material, it usually requires to be determined what are the modifying influences of formulation and delivery system(s). Both the toxicology testing program and the subsequent hazard evaluation procedure need to take these, and other, factors into account. Toxicology testing is discussed in more detail later. Also, emergency services require to be made aware of what first-aid and medical management measures will be necessary, and appropriate studies may be needed in this respect. Relationship of effectiveness to toxicity (hazard evaluation) Toxicity requires to be clearly differentiated from hazard, a more practical aspect which assesses whether the known toxic effect(s) of a material will be exhibited under the specific conditions of use. In this respect, it should be noted that while most of the participants in a riot will only be exposed for relatively short periods and for a single period or a few irregularly spaced periods, some subjects may be subjected to heavy acute overexposure (e.g. in poorly ventilated spaces). Also the participants, or accidental bystanders, in a situation of civil unrest belong to a heterogeneous population (male and female, young and elderly, and of variable states of health). The shorter the latency to onset of an effect and the more potent the material, the smaller will be the effective dose required to produce a given harassing effect. With irritants, because of the self-limiting nature of the experience the smaller will be the effective dose and hence the smaller the chance of inducing any toxicity, that is, the greater the safety ratio. If the ratio between sensory effectiveness and injurious dose is high this will be a significant factor in defining margins of safety-in-use. However, as discussed earlier, while increasing exposure concentration will shorten the effective response time, it does result in a larger inhalation exposure dosage to produce an equipotent harassing effect. Ease and control of use The material to be used should be capable of being delivered to its target by appropriate physical methods which combine safety (i.e. no significant enhancement of hazard) with the required degree of selectivity but without attenuation of the desired effect. Environment and decontamination When chemicals are dispersed in large amounts, particularly in urban areas, a very large number of differing environmental considerations need to be taken into account. These will depend, among other things, on the nature and physicochemical properties of the material, its stability and persistence, the amount used, formulation characteristics, and the local geography and geology. The diversity of considerations may cover, for example,



effects on sewage organisms, persistence and resultant decontamination of public and private property, effects on domestic animals, phytotoxicity, toxicity to fresh water organisms, effects of accidental contamination of food and/or drinking water since PSI materials may be detectable at very low concentrations (e.g. CR is detectable in drinking water at 3.16 105% (Kemp and Wetherell, 1975), and optimal methods for dealing with these and other potential situations.

12.5 BIOMEDICAL CRITERIA FOR EVALUATING HAZARD AND SAFETY-IN-USE OF RCA As noted above, a major recommendation of the Himsworth Committee (HMSO, 1969, 1971) was that an agent intended for use in peacekeeping operations should be assessed more from the viewpoint of a new drug than that of a weapon. However, in reaching this conclusion the Committee did make an important distinction in that with a new drug the acceptability involves a balanced consideration between the benefits and the risks; these are purely medical considerations. However, with a chemical intended for anti-riot purposes while some of the risk assessments are of a medical nature, other questions raise points of social policy and there must also be assessed on political grounds as well.

12.5.1 Toxicology In assessing the potential for adverse health effects, it is noted that most individuals who are deliberately or by accident at the scene of a civil disturbance will be exposed only once or for a few brief intervals and for comparatively short periods of time. Clearly studies on acute and short-term repeated toxicity by the intended route of exposure, primary irritancy, and sensitization studies are necessary as preliminary investigations. Since production workers and security forces may be repeatedly exposed over longer periods of time, longer-term repeated exposure studies are necessary for these circumstances. Indeed for several PSI materials, workplace exposure guidelines are available; for example, for CN a TWA of 0.05 ppm, and for CS a Ceiling Value of 0.05 ppm (ACGIH, 2001). However, in a civil disturbance there is the additional consideration that exposure is to a heterogeneous population with respect to age, sex, reproductive status, and state of health. Thus, there are also requirements for studies on developmental and reproductive toxicology, and genetic toxicology. The oncogenic potential of an RCA needs to be investigated with respect to those occupationally exposed to the material, but this is also an issue which may be raised by those who are involved in the sociopolitical aspects or by the concerned media. The following brief listing is of testing-needs which are regarded as generically required for an RCA, but is not necessarily a complete listing. Each toxicology testing program should be considered individually, taking into account the nature and intended use of the material, foreseeable misuse, and how toxicity could be modified by formulation and mode of dispersion. Special additional studies may be needed for each chemical and each operational application. Results should allow a definition of a NOAEL and a minimal effects concentration (dosage) for each toxic endpoint recognized (with essential data for hazard evaluation and risk assessment such as dosage/response and slopes of probit response lines). Details of the techniques used for toxicology testing are given in standard works such as Anderson and Conning (1993), Niesink et al. (1996), Ballantyne et al. (1999), and Hayes (2001). 1

Acute toxicity There is a clear need for single exposure studies by a relevant route or routes of exposure to determine lethal toxicity (LD50 or timed LC50) and


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2

3

4

5

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7

sublethal injury potential with dose–response relationships; no-effects levels are of prime initial importance. In addition to studies on the pure material it will be necessary to study the technical material, and to determine the influence that operational variants may have on toxicity; e.g., solvent or the effects of pyrotechnic decomposition products. Primary irritancy Since both airborne RCA or solutions of them may come into contact with skin and eye, it is clearly necessary to know if they produce inflammatory and injurious effects on skin and eye, and the possible modifying effects of formulation. It is of considerable value for eye irritation tests to be supplemented with objective evaluations of corneal thickness and intraocular pressure (Ballantyne et al., 1974; 1977b). Sensitization Again, since skin and the respiratory tract are the usual routes of exposure to RCA, there is need to determine the potential for them to produce skin and/or respiratory sensitization. In vivo and in vitro approaches are available (Kimber and Dearman, 1999). Repeated exposure studies There is a clear need from both the operational and occupational aspects to study the effects of repeated exposures in the short-term to determine the potential for cumulative toxicity. However, the need for subchronic and chronic toxicity/oncogenicity studies will require to be determined case-by-case taking into account such wide ranging considerations as exposure patterns, nature and biological reactivity of the RCA (including genetic toxicology), suspect biological activity, and sociopolitical demands. Developmental and reproductive toxicology As noted earlier, use of RCA against the heterogeneous population, particularly with respect to age, sex and reproductive status, demands that investigations should be carried out to assess potential embryofetotoxic, teratogenic, and reproductive hazards. Studies on the developmental toxicology of PSI materials, especially when exposure is to the aerosol, need careful design, particularly with respect to the stress caused both by the irritation and aerosol exposure during gestation (Upshall, 1973, 1977a). Genetic toxicology As a general guide to potential biological hazards, biological reactivity, and to assist in determining the need for repeated exposure studies, it is desirable to conduct studies to define the mutagenic and/or clastogenic potential of RCA. Metabolism and toxicokinetics These studies, by the intended route of exposure, may be of considerable value in assessing potential hazards and allowing quantitative risk assessments. Metabolism studies may give information of the possible effects of metabolites on the toxicity of the material. Studies on the uptake, biodistribution, and excretion of materials will aid in defining the potential for cumulative toxicity, possible target organs and/or tissues, and allow quantitative assessments of hazards. Such studies also help in the design and interpretation of repeated exposure studies. They may also be useful in circumstances where there are suspicions for adverse health effects based on misleading routes of exposure and/or biochemical considerations. For example, because of the malononitrile component, CS may be considered to be cyanogenic. Indeed following lethal intraperitoneal injections of CS in the rabbit, death due to cyanide poisoning was confirmed by measurement of blood and tissue cyanide concentrations, serum thiocyanate concentrations, and the degree of inhibition of tissue cytochrome oxidase activity (Ballantyne, 1983). However, in the context of the use of CS as an RCA, the biotransformation of malononitrile is insignificant because of the marked limitation on the inhaled dose due to the sensory irritant effects on the respiratory tract. For example, assuming complete retention, a dosage (Ct) of 10 mg min/m3 with a minute volume of 20 L would result in the absorption of 1.05 mole



8

CS and the maximum liberation of 2.1 mole cyanide. This is approximately equal to the cyanide content of two 30 ml puffs from a cigarette. Studies on the respiratory absorption of CS showed that exposures of rats and cats to 750 mg/m3 for up to an hour did not result in the detection of cyanide in blood or increased urinary thiocyanate concentration (Leadbeater, 1973; Upshall, 1977b). Additional and special studies Because of the variety of chemicals that may be used, and the differing circumstances of their use, there clearly may be special studies needed for a given material or a specific weapons delivery system. These studies may be required on a predictable preplanned investigation, or may arise from in-use incidents. Some representative examples follow. Riot control chemicals are used in circumstances where open physical injuries may occur, and thus there is a clear need to investigate the influence of certain chemicals on cutaneous wound healing (Ballantyne and Johnson, 1974b). The rubber-bursting grenade, mentioned above and used to produce a multifocal source of pyrotechnically generated irritant smoke, may result in injury from a direct wounding capability of scattered smoldering pellets. This additional source of potential trauma over that which could result from conventional grenade generated smoke sources required investigation (Ballantyne and Johnston, 1974a). An example of the need for special studies because of in-use experiences is provided by CS. Following the use of grenade generated CS smokes in Londonderry, Northern Ireland, on 13th and 14th of August, 1969, reports appeared in the newspapers describing cases of diarrhea, occurring particularly in infants and children (The Times, 1969; The Observer, 1969) The Himsworth Committee of Enquiry which investigated the use of CS concluded that there were certain features of the outbreak, including time of onset, that made them hesitant to ascribe the effect as due to CS (HMSO, 1969). Also, in controlled exposures to CS, diarrhea was only described as occurring in a very small proportion of subjects (c.1%) in one study (Punte et al., 1963), and not at all in another (Beswick et al., 1972). Isolated instances of a need to defecate have been described in volunteer subjects following the eating of food grossly contaminated with CS (Kemp and Willder, 1972). However, in order to clarify the possibility of an association between exposure to CS and the occurrence of diarrhea, an experimental study was conducted in which several species of laboratory animals which were given CS by gavage acutely or by 5 daily consecutive doses. There was no evidence of an increase in wet stool production, and no histological evidence for an irritant effect on the alimentary tract (Ballantyne and Beswick, 1972).

12.5.2 Human volunteer studies As has been noted, carefully conducted and controlled human volunteer studies in the laboratory or the field to study effectiveness of, for example, RCA, screening smokes and delivery systems, can readily be combined with physiological and biomedical monitoring to determine the effects of the various procedures on homeostasis, physiological function and possible pathophysiological consequences of exposure. In addition to clinical observations, volunteers have been monitored for hematology, clinical chemistry, respiratory function tests, ophthalmic studies (including tonometry and pachometry, [Ballantyne et al., 1977b]), and cardiovascular function. Such investigations are of value not only in assessing safety-in-use for the normal healthy population, but also against special subpopulations including those with established ill-health (e.g. cardiovascular disease, respiratory disease, aneurysm, glaucoma, etc.). They clearly complement the toxicology studies and are of considerable value in hazard evaluation. The results of the toxicology studies, combined with the findings from human volunteer investigations, should also


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be of value for defining any operational restrictions of an RCA, and its formulation and/or delivery systems. Such trials, usually started at threshold levels (doses) should be conducted with the appropriate medical cover, and only in informed volunteer subjects who have signed documentation indicating they have been fully informed of the procedures to be conducted and any possible complications. The proposed studies should have prior approval by the appropriate medical ethical committee and independent advisory group, who should be informed of the results, and whose authorization for extension of the work should be obtained. A written signed record of the minutes (discussions) of these committees and advisory groups should be kept.

12.6 CAUSES OF INJURIES AND MORTALITIES IN PEACEKEEPING OPERATIONS: MEDICAL AND FORENSIC IMPLICATIONS Casualties to malefactors or those caught up by chance in an incidence of civilian disobedience may result from direct (primary) chemical injury from the RCA used (overexposure); from ballistic or thermal trauma from the mode of dispersion; from misused situations (e.g. confined spaces), or from the emotion or panic of being involved in a civil disturbance. Security and/or emergency services may therefore be faced with the following (mainly unintended) situations.

12.6.1 Physical injuries (i)

(ii)

(iii)

Projectile injuries These may be deliberate as in the use of rubber bullets and plastic bullets (baton rounds) where the degree of civil unrest makes their use needed for crowd dispersal. The earlier weapons had poor aerodynamic characteristics. They may cause local bruising, fractured bones (including skull and face), visceral injury, and eye trauma. Deaths have resulted secondary to trauma (Marshall, 1976). More than a quarter of a century later, and in spite of a Human Rights Commission statement that the newer plastic bullets are more dangerous than those they have replaced, these projectiles continue to be used with a high casualty yield, most recently in San Francisco, Los Angles, and Buenos Aires (BBC, 2003). Smoke or tear gas grenades launched remotely from dischargers may cause physical injury by direct impact. Physical and thermal injuries Grenades or canisters which are picked up before they detonate may cause burns as well as explosive injuries. Also, if they are projected into enclosed spaces (e.g. rooms) they may cause burns secondary to ignition of the area contents. Special devices, such as the bursting grenade may cause local burns by lodgment of smoldering pellets between clothing and skin. Tear gas pen guns or pistols discharged close to the body, particularly the head and neck have caused severe and sometimes fatal injuries (Stahl et al., 1968; Hopping, 1969; Stahl and Davis, 1969; Ayers and Stahl, 1972; Smialek et al., 1975). Panic injuries If sensory irritants or projectiles are discharged close to groups of persons they may result in a panic situation with resultant injuries. A recent example of this was in a Chicago night club during February, 2003, when a security guard attempted to break up a dance floor fight by using a pepper spray. This started a stampede of several hundred persons towards the front door, resulting in the death of 21 persons (USA Today, 2003). In addition to the purely panic effects of such situations, difficulty to escape may be compounded by blepharospasm



(iv)

and excess lacrimation induced by a PSI. A less dramatic, but still instructive example was seen in Leicester, UK, in which 23 persons had to attend the accident and emergency department of a hospital following exposure to CS aerosol in a crowded nightclub (Breakell and Bodiwala, 1998). Incidental physical injuries and accidents With water canon, physical injuries may result from running to escape, which is impeded by the slippery surface of the wetted ground. If airborne PSI materials drift from their intended site, they may access areas where motorized vehicles are present, which could lead to difficulties in vision with the drivers and resultant accidents. A similar situation could apply if low viscosity polymers were employed. Arrest and in-custody deaths may result from restraint techniques used, positional asphyxia, and restraint in cases of cocaine intoxication, marked alcohol involvement, and the neuroleptic malignant syndrome. These have been discussed in detail elsewhere (McLaughlin and Siddle, 1988; Lifschultz and Donoghue, 1991; Bell et al., 1992; Luke and Reay, 1992; Reay et al., 1992; Granfield et al., 1994; Steffee et al., 1995).

12.6.2 Chemical injuries (i)

Eye injuries Contamination of the eye with a PSI in the form of an aerosol, a solid, or in solution, in addition to causing distress due to the discomfort may result in a marked conjunctoblepharitis. Although this normally resolves within minutes to a few hours postexposure, prolonged exposure to CN aerosols may cause severe persistent conjunctoblepharitis and possibly corneal injury (Thorburn, 1982). Heavy exposure to CN may produce necrosis of the corneal epithelium (Grant, 1986). Injury to the eye has been described with liquid projection hand-held (‘self-protection’) devices, principally those containing solutions of CN. Laboratory studies show a threshold for corneal injury at 1% in polyethylene glycol 300, with severe keratitis occurring at 2% (Ballantyne et al., 1975). Eye injury from Mace has been documented (Kling, 1969; MacLeod, 1969; Pearlman, 1969; Rose, 1969; Macrae et al., 1970; Oksala and Salminen, 1975). Discharge of particulate irritant from tear gas pen guns has been associated with eye injury, again mainly with CN devices (Oaks et al., 1960; Hoffmann, 1967; Hopping, 1969) . Effects have included chemosis, corneal edema, corneal epithelial stripping, necrotizing keratitis, and iridocyclytis (Levine and Stahl, 1968; Laibson and Oconor, 1970). The initial severe eye injury is probably a consequence of physical damage from blast and heat coupled with explosive deposition of solid particles in the wound leading to chemical necrosis. The chronic nature of many of these injuries is probably mainly due to the persistent effects of embedded chemicals. Corneal abrasions have been seen after individuals have been exposed to OC sprays (Brown et al., 2000). Contamination of the eye with solutions of a PSI (e.g. from a hand-held self protection device) can result in a transient increase of intraocular pressure (Ballantyne et al., 1973b, 1977b). Pressure increases mainly in the contaminated eye, and to a lesser degree and shorter duration in the contralateral eye. Both local and systemic causes may be responsible for the increased pressure. Locally there is probably an impairment of aqueous humor drainage due to hyperemia and/or congestion of the conjunctival vessels with ocular compression due to blepharospasm. Systemically, there is increased central venous pressure which will further impede aqueous drainage (Ballantyne et al., 1973b; Rengstorff et al., 1975). The ocular hypertension is unlikely to be significant for those with normal vision, but may precipitate or exacerbate problems in persons with established glaucoma (Ballantyne, 1977; Ballantyne et al., 1977b).


RIOT CONTROL AGENTS

(ii)

(iii)

Skin Injuries With harassing, but otherwise relatively low dose exposures to PSI materials, the only visible cutaneous effect is normally erythema. However, sustained exposure to high CN concentrations may result in severe erythema, edema, and skin burns (Thornburn, 1982). CN, and to a lesser degree CS, may cause allergic contact dermatitis (Penneys et al., 1969; Rothberg, 1970; Penneys, 1971; Holland and White, 1972; Frazier, 1976; Ballantyne, 1977; Pfeiff, 1984; Leenutaphong and Goerz, 1989; Fuchs and Wiesche, 1990; King et al., 1995). Respiratory Tract Injuries The discomfort, breathing difficulties and cough associated with exposure to an airborne PSI usually resolve within 10 min to an hour or so. Sustained exposure to high concentrations may result in laryngotracheobronchitis (Thorburn, 1982). It is possible that exposure of hypersusceptible individuals may result in laryngospasm, possibly fatal. Lung injury is most likely to occur when there is exposure to high aerosol concentrations, particularly of grenade generated smoke, in areas with poor ventilation, and from which escape is difficult ; e.g. a barricaded room or cell, or automobile (Thorburn, 1982; Greaves, 2000). Several cases of fatal respiratory tract injury have been recorded from such acute overexposure situations, particularly with DM and CN but also CS (Gonzales et al., 1954; Stein and Kirwan, 1964; Ministry of Defence, 1972; Chapman and White, 1978; Krapf, 1981). Death usually occurs between 12 h and several days postexposure. It is pathologically characterized particularly by laryngeal and tracheobronchial necrosis with pseudomembrane formation, pulmonary edema, and alveolar hemorrhages (Stein and Kirwin, 1964; Chapman and White, 1978). If respiratory tract injury occurs, secondary infection may develop. In circumstances where it is considered there is no alternative to the use of a PSI for evicting a deranged or dangerous individual, or individuals, from enclosed spaces with perhaps inadequate ventilation, then the use of the smallest munition possible should be considered and, if available, the employment of devices not utilizing pyrotechnic methods for an aerosol generation.

12.7 DECONTAMINATION, FIRST-AID AND MEDICAL MANAGEMENT OF CASUALTIES IN PEACEKEEPING OPERATIONS As will be anticipated from the discussions here, the emergency services and physician may expect casualties from a civil disturbance to vary from simple irritant and emotional effects with prompt recovery to severe chemical and/or physical injury necessitating hospital admission. Advance knowledge of the procedures to be adopted by the security forces will greatly aid the emergency services, including hospitals, in what preparations may be necessary. If civil unrest develops into violent demonstrations or chronic urban riots, this will enormously increase the requirements for health care and social services. For example, after the use of CS grenades in a Vietnamese detention center in Hong Kong during 1995, some 1,500 people were transferred to a British Red Cross Medical Clinic for assessment and treatment (Anderson et al., 1996). The wider medical and social problems and appropriate planning have been considered in several publications (Walt et al., 1967; Frank et al., 1969; Hayman and Berkeley, 1971; Robb and Matthews, 1971). Arrangements for triage and to exclude injuries or complications may be required if large numbers of persons are likely to be involved, but most patients will rapidly recover. It is important to reassure the individual that recovery will occur promptly and without any adverse sequelae. A typical presentation to an airborne sensory irritant is as follows, with which emergency service personnel and physicians should be familiar. There will be pain or discomfort (itching, stinging, or burning sensation) in the eye, nasal and oral cavities,



throat, and larynx with burning and/or constricting sensations in the chest. These are accompanied by blepharospasm, excess lacrimation, rhinorrhea, excess salivation, increased tracheobronchial secretions, sneezing, coughing, retching, and difficulty with breathing, including breath holding. If contaminated saliva is swallowed there may be nausea, and in extreme cases vomiting. Visual acuity may be slightly reduced immediately after contamination of the eye, and while the subject is symptomatic, but acuity rapidly returns to normal (Rengstorff, 1969b; Yih, 1995). With solutions, the sensory effects are confined to the body area contaminated, and the reflex effects are a function of the afferent nerve involved. In general, effects appear within a few seconds of exposure and slowly subside over the next 10 min to a few hours.

12.7.1 Decontamination and medical management Ideally a separate well ventilated area should be available to receive, examine and decontaminate exposed individuals. In many cases where exposure has been symptomatic but briefly sustained then decontamination in a fresh air stream is the optimum approach and sometimes this is all that is required (Lee et al., 1984; Blaho and Stark, 2000). Contaminated clothing should be placed in plastic bags. Disposable gloves and gowns should be worn when handling patients in order to avoid transfer of RCA. If decontamination requires showering or washing, then the patient should be advised so that this may result in a temporary reprise of symptoms as water leaches PSI out of contaminated hair. If a patient is in need of specialist care, such as surgery, then it is essential that the individual be as far as possible totally decontaminated, since secondary contamination of medical staff may present management problems. For example, in those exposed to RCA, intubation may prove difficult for the anesthetist (Bhattacharya and Hayward, 1993).

Eye Acute chemical conjunctoblepharitis may be present from aerosol of liquid PSI contamination of the eye. In mild cases of aerosol exposure, aeration in the open air or using an electric fan may be all that is required for decontamination and relief (Lee et al., 1984; Yih, 1995; Blaho and Stark, 2000). In more marked cases gentle decontamination of the eyes may be required by irrigation with water or saline for several minutes. If discomfort is extreme or persists, the use of local anesthetic eye drops may be useful; for example propoxymetacaine hydrochloride. The use of local anesthetics should be restricted to essential cases, and ideally have the authorization of an ophthalmologist, since they may impair the regeneration of the corneal epithelium and retard healing (Leopold and Leiberman, 1971). It is recommended that contact lenses should be removed to ensure that entrapped PSI can be irrigated. Soft lenses contaminated with OC should be discarded because it may be difficult to remove residual material (Lee et al., 1996). Those having marked and persistent eye discomfort with blepharospasm should have a detailed ocular examination (possibly including fluorescein staining and biomicroscopy) to confirm the absence of corneal or anterior segment injury (Brown et al., 2000). As discussed in detail earlier, contamination of the eye with solutions of PSI materials causes a transient increase in intraocular pressure. While this is of no significance in those with normal eye function, individuals with established or incipient glaucoma may be at risk, and should receive appropriate expert ophthalmic examination and advice.

Skin Skin erythema is normally all that is seen. Skin may be decontaminated with a copious soap and water wash. With CS, and if the symptoms are marked, advantage may be taken


RIOT CONTROL AGENTS

of its rapid hydrolysis in alkaline solution. Weigand (1969), for example, recommended use of the following solution which is sufficiently alkaline (pH 9.4) to produce rapid hydrolysis and prompt relief of symptoms; aqueous 6% sodium bicarbonate, 3% sodium carbonate, and 1% benzalkonium chloride. Usually, however, either aeration or simple water wash is sufficient. Sustained exposure to high concentrations of grenade generated smoke, particularly CN, may cause a more severe primary irritant dermatitis, requiring therapeutic measures; for example, topical corticosteroids. Also, a hypersensitivity reaction may be present in a minority of individuals, although this is more likely to be present in the more frequently exposed security forces. Perforating injuries with embedded CN may provoke severe chronic suppurative, and necrotizing reactions resulting in degenerative changes and fibrosis affecting skin, nerve, and muscle (Adams et al., 1966; Stahl et al., 1968).

Respiratory tract Respiratory effects usually subside rapidly and completely if exposure was outdoors. However, if exposure was sustained, and particularly if it occurred in an enclosed space, then the patient should be kept under observation and, as dictated by the clinical circumstances, radiological studies, lung function tests, and blood gas analyses, conducted. Those with established chronic pulmonary disease and asthma, may have an exacerbation of their symptoms, for which usual treatment remains unchanged. With sustained overexposures to grenade generated smokes laryngotracheobronchitis may develop, possibly requiring bronchodilators, postural drainage, and corticosteroids (Thorburn, 1982). The possibility for secondary infection should be kept in mind for those having postexposure respiratory tract injury. Reactive airways dysfunction syndrome has been described occasionally following acute overexposure (Hu and Christani, 1992; BayeauxDunglas et al., 1999; Worthington and Nee, 1999).

Cardiovascular status Exposure to aerosols or solutions of PSI materials may produce a transient increase in systolic and diastolic blood pressure, sometime accompanied by a mild to moderate bradycardia (Ballantyne et al., 1976; Ballantyne, 1977). This, could compound with that caused by the emotional experience of being involved in a civil disturbance, and those who give a history of cardiovascular disease (including essential hypertension, cardiac arrhythmias, myocardial infarction) may require appropriate monitoring.

General and unusual The circumstances of a civil disturbance, particularly if large and if experienced by an innocent passer by, may be disturbing and result in psychological casualties, including the development of hysterical and delayed reactions. Such psychological disorders may also be shown by those living in areas where the threat of violence exists (Frazer, 1971; Lyons, 1971). They may require appropriate sedation and reassurance from psychiatric social workers, whose presence should be made available. Very rarely the following complications have been described with CS; hemoptysis and hematemesis (Anderson et al., 1996), and multisystem hypersensitivity reaction (Hill et al., 2000). The possible use of habit-forming drugs by some participants in civil disturbances should be kept in mind (Hayman and Berkeley, 1971). Physicians should be aware of the possibilities of complications from formulation components, and advance information can be of essential help in this respect. For example, Duenas et al. (2000) described several cases of carbon monoxide poisoning resulting from inhalation exposure to the spray from a CS personal defense containing 0.8% CS in dichloromethane, the latter solvent being known to be



metabolized to carbon monoxide (Horowitz, 1986). With CS-containing spray canisters the solution should not be aqueous because of the rapid hydrolysis of CS (t 1/2 14 min; pH 7.4, 25C). In the UK, methyl isobutyl ketone is a major component of the formulation, and which may itself produce a moderate primary skin and eye irritation, but more sustained than that resulting from CS (Gray, 2000).

12.8 ROLE AND EXPECTATIONS OF THE COMPETENT AUTHORITIES IN PEACEKEEPING OPERATIONS Ideally, and because of the detailed organizational needs, preplanning requirements, operational considerations, medical, social, ethical, legal, and organizational aspects of peacekeeping operations (in the broad spectrum discussed here) the regulating competent authority should be at a central government level. The central competent authority will, by necessity, need to coordinate with, and authorize the activities of, regional (local) government bodies. However, at this time the preparations for, and authorization of, the use of control measures against those causing a disturbance of the peace show a widely differing scope and extent depending on geography; and indeed within a country there may be regional variations in procedures, policies and authorizations. Some countries have a central control in policies and procedures for the involvement of security forces in peacekeeping operations (e.g. the Home Office in the UK) whereas in other countries the legal situation varies geographically (e.g. by State in the US). However, the recent activities to prepare for and make preparations against possible terrorist activities by some National authorities could be used as a convenient focal area for considerations related to civil disobedience. The causes, circumstances, procedures, and involvement of security forces in civil disobedience situations markedly differ from, and in some aspects contrast with, those of anti-terrorist operations. However, the central commonality of many specialties, information and politico-legal resources, communication channels, and coordination with security forces (notably police and armed services), the umbrella coverage of (particularly) riot control under the central competent for homeland security would have many advantages, including economic, planning, operational, communication, scientific, medical, communication, and coordination. However, there could be some sensitive legal and sociopolitical constraints on a strictly combined function, and on the subsequent policies, procedures, and authorization (command and control). Nevertheless, any competent authority with responsibility for civil disobedience can be expected to have the following responsibilities and accountabilities. 1

Safety evaluations The authority should have undertaken complete hazard evaluations and risk assessments for the procedures to be used, including the safety of chemicals, and their modes of delivery, in the context of use against a mixed civilian population. Ideally these assessments should have been reviewed by expert independent and credible advisory committees, and the results made available for public scrutiny in a manner that ensures transparency of the processes and views of the competent authority. This was also a recommendation of the Himsworth Committee who stated that “—if the competent authorities feel it justifiable to release a chemical agent for use in civil circumstances, the medical and scientific research relevant to this decision should straight away be published in the appropriate scientific journals so that informed medical and scientific opinion may


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assess the situation for itself—” (HMSO, 1971). Relatively few risk assessments for the use of chemicals are available, but have been published, for example, for pepper spray (oleoresin capsicum) (Busker and van Helden, 1998) and CS (HMSO, 1969, 1971). There should be provision for periodic re-review of assessments and recommendations. Information resource The authority should have available, or ready access to, all literature (basic research, development, and review) relevant to the practices and procedures they recommend. This is, in part, related to the function of ensuring that a complete evaluation of potential health hazards from chemicals and procedures is undertaken (see), and also in part to ensuring the credibility and completeness of statements made. Coordination with emergency and support services The very nature of circumstances of civil unrest mean that there may be injuries of various types and degrees, destruction of property, fires, and disruption of local amenities. It therefore follows that the security forces need the cooperation of support and emergency services such as firefighting, ambulance, emergency medical, and social services. A coordinating role with media may also be useful. The overall guidance and planning of these arrangements should initially be discussed and planned centrally to ensure consistency and agreement of optimum approaches. The manner in which these support services are contacted and coordinated in an actual situation is clearly a local matter, but should be planned in advance and included in training exercises. Oversight of education and training In some situations of civil unrest, there have been accusations that security forces may not have been fully trained in the use of chemicals and equipments and that injuries have been a consequence of this (Hu et al., 1989). It therefore seems appropriate that competent authorities should advice on the need for, and planning of, educational courses and training exercises for the security forces. Such a function by the central competent authority would ensure that there would be consistency in the guidelines, practices, and policies used by individual local security authorities. Proper education should cover the psychology of civil unrest, physical and nonphysical methods for control, and when appropriate, complications that may result from the use and misuse of riot control procedures and how to minimize or correct these. Training sessions should be conducted, and there should be provisions for random audit of the procedures and practices. Advice and information dissemination Advice and information should be made available on the practices and procedures to be used in the event of civil unrest, including the nature of chemicals to be used, and approaches for decontamination and the treatment of overexposed individuals. In this way the emergency and health care facilities can be appropriately prepared. Failure to appropriately inform may result in significant medico-legal issues and adverse public comment. Although mainly in the area of anti-terrorist activity, a recent incident of the failure to inform serves to demonstrate how this can result in severe problems and criticism by the international community. This specific incident involved the use of a “debilitating gas” by Russian security forces against Chechen rebels who held about 800 people hostage in a Moscow theatre during late October 2002. Pumping the gas into the theatre (for about 30 min) resulted in the death of 119 hostages at the scene of the incident and over 200 required hospital admission. The identity of the agent used was not made available in advance to local hospitals and medical personnel, and it was only some 5 days after the incident that the government authorities declared that the substance used was the narcotic analgesic, fentamyl (BBC, 2002).



12.9 THE ADVISORY ROLE OF THE FORENSIC EXPERT IN PEACEKEEPING SITUATIONS It follows from the discussions made in this chapter that the use of RCA in circumstances of civil unrest may lead to many subsequent enquiries, comments, and complaints; these may originate from a wide range of sources including news agencies, those members of the public involved directly or incidentally in the disturbance, those who may have been injured, those involved in litigation, and lawmakers, It is clear that, under these circumstances the forensic expert should be expected to demonstrate expertise, impartiality, professional ethics, and clarity. Expert witness considerations have been presented in detail elsewhere ( Furst, 1997; Furst and Reidy, 1999). A limited number of authoritative reviews dealing with the management of casualties from civil disturbances have been published (Ballantyne et al., 1973b; Ballantyne, 1977, 1987; Beswick, 1983). However, there are no widely published clear-cut guidelines or recommendations, official or unofficial, on the procedures to be adopted in the difficult and often changing situation of a civil disturbance. This has, on occasions led to suggestions of the misguided use and misuse of forceful methods for control of these situations by security forces. The accusations of misuse patterns, of excessive force, and of resulting injuries, and in a few cases mortalities, have resulted in increasing litigation against security forces. In these circumstances the role of an independent reviewer and advisor can be of indispensable value. In this respect, the forensic expert can expect to be asked to give expert guidance, and maybe testimony, on the following issues for purposes of information, reassurance, and possible litigation. Enquiries may originate from wide ranging sources including the competent authorities, other government departments, legal services and litigation attorneys, reporters from television and radio companies and newspapers, and private citizens. The following are some of the major issues that the forensic and related experts may be called upon for advice, and maybe to give testimony. They represent but a few illustrative examples of what is a wide spectrum of potential needed assistance. 1

Was the death of an individual directly related to the circumstances of a civil disturbance at which the deceased was present. This is clearly a wide ranging question, mainly in the area of the forensic pathologist and toxicologist, which may cover a variety of scientific, medical, and possibly operational aspects. The considerations will depend, among many other factors, on the circumstances of the death, its timing, the previous health status of the individual, and the findings of the autopsy. Each case will require a detailed case-by-case consideration taking into account all factors. These will include, but clearly not limited to, the following, which should merely be regarded as representative considerations. ●

●

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2

Was the death a result of primary chemical injury; e.g. what was the nature of, and degree of exposure to, any RCA used; for example was there sustained exposure to high concentrations in an enclosed space. Was death secondary to physical and/or thermal injuries sustained in the disturbance; e.g. head injury from baton rounds. Could the preexisting health status of the individual have been a significant contributory factor; e.g. an increase in systemic blood pressure precipitating or exacerbating cardiovascular disease, or resulting in rupture of an aortic or intracerebral aneurysm. Did any arrest or restraint procedures contribute directly or indirectly to death.

Were any immediate or delayed-onset injuries sustained by a person at the scene of a civil disturbance a direct consequence of the procedures used by the security


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forces. This may cover physical and/or thermal injuries from missiles or exploding grenades, a combination of chemical injuries and physical injuries, or chemical injuries resulting from a direct toxicity of the material(s) used. Clearly this demands a knowledge of the ballistics of the delivery systems as well as a detailed knowledge of the toxicology of the RCA used and the formulations. Could exposure to the conditions of the civil disturbance have exacerbated prior ill-health conditions in the individual. This clearly demands a knowledge of general medicine as well as of the circumstances of the disturbance, and the agents and dissemination methods employed. Was an appropriate action taken in controlling a particular situation, especially if a disturbed person had to be subdued. This raises the question of whether the security forces are trained by or, more desirable, have access to forensic psychiatrists and psychologists who can recognize the signs and symptoms of mental disturbances, which may require special negotiation methods for control (Danto, 1987). What agent(s) were used in a particular situation, and/or was a individual or group of individuals exposed to a particular material (e.g. PSI). This clearly needs a detailed knowledge of the signs and symptoms experienced by exposed subjects, how these may vary, and what are the potential complications. Studies have been undertaken on the stability of PSI materials, and methods have been developed for the chemical identification and confirmation of commonly used irritants, including capsaicin, dihydrocapsaicin, CN, CS, and CR ( Sreenivason and Boese, 1970; Gag and Merck, 1977; Fung et al., 1982; Raghuveeran and Malhotra, 1982; Allinson and McLeod, 1997; Kataoka et al., 2002; Reilly et al., 2002). Most approaches involve off-site analysis of wipe samples, which should be collected as soon as possible and the samples kept in closed containers (Kataoko et al., 2002). However, methods for on-site identification have been described, for example, using ion mobility spectrometry (Allinson and McLeod, 1997). Were single or multiple injuries in a civil disturbance a consequence of the wrong use of a particular RCA in a given situation, or misuse of the methods for its dispersion. This also is a wide ranging question necessitating detailed information on the circumstances of the disturbance, the nature of any chemical(s) used, the methods for their (its) dispersion, and the experience, training and motivation of the security forces, and were the practices employed excessive for the given situation. Was the material (RCA or formulation constituent) used in a civil disturbance appropriately tested before its release for use in such circumstances. This clearly needs a detailed toxicological review of the types of studies conducted, and their scientific adequacy and credibility, against the background of the nature of the material and its potential biological reactivity against a heterogeneous civilian population.

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preparedness training for nonclinical hospital workers: empowering them to take action. J. Occup. Envir. Med., 45, 333–337. UPSHALL, D.G. (1973) Effects of o-chlorobenzylidene malononitrile (CS) and the stress of aerosol inhalation upon rat and rabbit embryonic development, Toxicol. Appl. Pharmacol., 24, 45–59. UPSHALL, D.G. (1977a) Embryonic development and inhalation stress. In: B. BALLANTYNE (ed.), Current Approaches in Toxicology. Bristol: Wright, pp. 79–85. UPSHALL, D.G. (1977b) Riot control smokes: lung absorption and metabolism of peripheral sensory irritants, Proc. European Society of Toxicology, Edinburgh, vol. XVIII. Amsterdam: Excerpta Medica, pp. 121–127. USA Today (2003) Chicago club may loose its licenses. USA Today, February 20th, Section A, p. 4. WALT, A.J., WILSON, R.F., ROSENBERG, I.K., ARBULA, A., GRIFKA, T.J., KOBOLD, E.F., and LUCAS, C.E. (1967) The anatomy of a civil disturbance, J. Amer. Med. Assoc., 202, 394–397. WEIGAND, D.A. (1969) Cutaneous reaction to the riot control agent CS, Mil. Med., 134, 437–440. White House (1994) Riot control agents: Press release dated June23, 1994. Office of the Press Secretary, White House, Washington, DC. WITTEN, B., WAGMAN, W., SAFFER, R., and COHEN, L. (1970) Malodorous substances as riot control and training agents. Edgewood Arsenal Technical Report No. 4370, Department of the Army, Edgewood Arsenal, Maryland. WORTHINGTON E. and NEE, P.A. (1999) CS exposure – clinical effects and management, J. Accid. Emerg. Med., 16, 168–179. YIH, P.-H. (1995) CS gas injury to the eye, Brit,. Med. J., 311, 276.


CHAPTER

An Approach for Assessing and Characterizing Risk from the Use of Riot Control Agents

13

JACQUELINE PATTERSON1, BERT HAKKINEN2, PATRICIA NANCE1, MICHAEL DOURSON1, AND B. JON KLAUENBERG3 1 Toxicology Excellence for Risk Assessment (TERA), 1757 Chase Avenue, Cincinnati, OH 2 European Commission, Institute of Health and Consumer Protection, (Italy) 3 Non-Lethal Weapons, Human Effects Center of Excellence, Brooks AFB, TX

13.1

INTRODUCTION

Determining the risk to humans intentionally or unintentionally exposed to riot control agents (RCAs) requires a careful consideration of the potential toxicity of the agent, the exposure situation, and concentrations to which the persons are exposed. A comparison of the resulting estimated external (e.g. skin surface) and internal (e.g. respiratory tract) doses with what is known of the agent’s toxicity via relevant routes of exposure allows one to characterize the risk for the population of interest (be it the target, bystanders, or those deploying the RCA). The assessment of risk is conducted in conjunction with an evaluation of an agent’s effectiveness (e.g. levels of exposure needed to achieve a desired control effect) to gain an understanding of both effectiveness and risk and how each changes with different exposure situations or conditions. A framework for characterizing effectiveness and risk from exposures to situations such as those where RCAs may be used has been developed (TERA, 2001). The framework adapts common approaches to human health risk assessment (concerned with exposures to chemicals from water, soils, air, consumer products, and foods) to address these other types of situations and materials. This framework draws heavily upon the risk assessment paradigm developed by the (United States) National Academy of Sciences (NAS, 1983; NAS/NRC, 1994). The resulting knowledge can help evaluate the safety of reasonably foreseeable exposures to the RCA being assessed, and will help identify any areas of uncertainty and opportunities for refinement of the risk assessment. It could also be used to consider reformulation or redesign of the RCA and/or its delivery system, or recommendations for RCA usage (e.g. use under specific scenarios and weather conditions).


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RCAs are solids with low vapor pressures and are generally dispersed as fine particles or in solution from a variety of devices which include small spray canisters carried on the body (e.g. in a pant or coat pocket, or inside the sleeve along the wrist), large spray tanks, grenades, and other larger devices (e.g. helicopter- and shoulder-fired rockets), and launching devices that deliver canisters. These chemicals are intended to temporarily disable a targeted individual by way of sensory irritation of the eyes, respiratory tract, and skin. When used as intended, these agents are generally regarded as safe and of low toxicity. However, under increased exposure levels or prolonged durations of exposure they may have toxic effects (Olajos and Salem, 2001). Chapters 4–11 have provided detailed information about the potential toxicity to humans from exposure to the various RCAs. This chapter will describe the phases and steps of the risk characterization framework and approach (TERA, 2001), and explore its applicability for assessing intentional uses of RCAs. This chapter will not describe an actual assessment and will not attempt to quantify the risks from use of RCAs, but rather provide a qualitative discussion of how such an assessment and characterization might be conducted.

13.2

RISK CHARACTERIZATION FRAMEWORK

The risk characterization framework and approach described here was developed for the Department of Defense (DoD) by Toxicology Excellence for Risk Assessment (TERA) and a group of scientists experienced in decision analysis, risk assessment, modeling, and probabilistic dose–response and exposure assessment (TERA, 2001). TERA and the group of scientists met in a workshop with individuals from the DoD and its contractors, knowledgeable in nonlethal weapon (NLW) technologies and human effects. The resulting framework is an approach for evaluating risks and effectiveness of a particular NLW for a defined exposure situation. Figure 13.1 illustrates the four phases of the conceptual risk characterization framework (effects identification, dose–response, exposure assessment, and data needs). These are based on the risk assessment process, as outlined by the NAS (1983) and practiced in the areas of environmental clean up and standard setting. The framework facilitates the organization and evaluation of available data, the communication of risks and benefits to different levels of decision-makers, and the identification of research needs. It allows for the integration of information on intended target effects and effectiveness, as well as the risks of unintended effects. The framework includes a series of steps, which identify the types of human effects anticipated, the relationship between the amount of “dose” or force and the resulting physiological response, and the effect of exposure conditions on the amount of force or “dose” received by the person(s). This information is all combined to describe the potential risk of unintended effects on the target, operator/user, or bystander from use of a NLW for a given scenario. This description may include the probability of a certain type of injury or death occurring given the identified circumstances. If the data are more limited, the results may provide an indication of the margin of exposure between the amount of exposure likely to result from a given situation and the dose that would induce intended or unintended effects. A simple probabilistic software model has been developed to demonstrate the use of the framework. With input data on exposure parameters and dose–response information, the model estimates how many people would be affected and what types of effects they might encounter. Like any model, it is only as precise as the data used. More robust models could be constructed that would consider more complex crowd behavior and quantify the uncertainty in the model predictions. The results of risk characterization provide decision-makers with the probability of intended effects and unintended effects so that the risks can be weighed against the benefits of using the weapon.


Effects ID

Dose response

Risk characterization

Exposure assessment

Start

No

Start

ID relevant variables for scenarios of interest

Probabilities of intended, unintended

Effects identified?

Yes Yes Exposure–dose curves

Required

Dose–response curves

Dose–response data?

Research

No

No Required

Quantitative data on variable(s)?

No

Risk characterization description

Yes

Qualitative data on variable(s)?

Nonlethal index (NLI)

No Required

Threshold data?

Yes

Yes Effective dose (ED)

Point estimate ratios

Exposure estimate

Figure 13.1: Conceptual framework for risk characterization. This flow chart outlines the steps needed to characterize risk from use

261

of nonlethal weapons. The risk characterization description is the end result of the process, reflecting the hazard identification and dose–response data from the left side incorporated with the exposure assessment results from the right side. The results in the risk characterization column (either probabilities or point estimate ratios) reflect the type of decision needed as well as data available from the dose–response and exposure assessments (adapted from TERA, 2001).


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The following sections more fully describe the four phases and qualitatively discuss considerations for characterizing risk from RCAs.

13.2.1 Effects identification The first phase of the risk characterization framework is the process of identification and discussion of all possible effects of the RCA; both those that are intended and those that are not. It is important to distinguish between “intended effects,” those effects to the persons targeted which are desired and should result in the target changing their behavior (e.g. stopping or leaving the area), and unintended effects. While the ultimate intended effect of an RCA is a behavioral response by the target person(s), generally, only the physiological effects (e.g. eye or pulmonary irritation) are directly measurable and therefore it is these physiological effects that are the focus of this approach. Unintended effects are those that produce unacceptable injury to the targeted individuals. In addition, those effects that are intended for the target may be considered unintended effects when experienced by uninvolved bystanders. The determination of intended and unintended is a judgment based on the context in which the agent is used and is thus made by personnel at the time when its usage is under consideration. Traditional human health risk assessment focuses on the adverse and undesired effects of exposure to an agent and calls this step “Hazard Identification.” However, for the purposes of characterizing risk from intentional use of an RCA, not all effects are considered undesirable, and one goal of the process is to determine the magnitude of difference between exposure causing intended effects and those causing unintended effects. It is this area, which the RCA user would want to maximize to allow for effective use of the agent, without adverse and undesirable effects on the target, user, or bystander. In the effects identification phase, the analyst gathers and evaluates data on the types of health injury or disease that may be produced by the agents, and to the extent possible tries to understand the behavior of an agent within the body, including the interactions it undergoes with organs and cells. Data on the conditions of exposure under which the injury or disease is produced are also evaluated. The first decision point is to determine whether relevant physiological effects have been identified and if there are sufficient data available. A qualitative description of the effects may be derived from both a direct and a “weight-of-the evidence” analysis of various sources including data from humans or laboratory animals and ancillary data from other studies. If there are not sufficient data to identify the RCA’s effects, more research would be necessary. Obviously, without knowledge of the potential effects from an agent or substance, one would not have dose–response information, and cannot characterize risk. RCAs are sensory irritants which elicit their effects generally on the eyes, skin, and respiratory tract. Pain, burning sensation, and irritation of exposed mucous membranes and skin are the main effects of RCAs. Olajos and Salem (2001) indicate that RCAs can be classified physiologically as lacrimators, vomiting agents, or sternutators. The first group will cause eye irritation and tearing, the second group will cause vomiting, and the final group produces uncontrollable sneezing and coughing. Typical characteristics of RCAs include rapid onset, with a short period of activity after exposure ceases. The lacrimatory effects of many of the chemicals can range from mild to severe, including stinging of the eyes and tearing at low concentrations, resulting in temporary disablement. At low levels these compounds will cause reversible effects with no serious injury. At higher levels or prolonged durations of exposure there is potential for more serious injuries, such as corneal edema, corneal ulceration and scarring, corneal opacification, and corneal vascularization. RCAs can also affect the skin, producing tingling or burning sensation, and transient erythema. Edema and blistering can be seen at higher concentrations of some agents such as


ASSESSING AND CHARACTERIZING RISK OF RCA

CN, CS, and DM. At this initial stage of assessment, no attempt is made to determine the likelihood of occurrence or whether certain effects are intended or unintended responses. As discussed in the previous chapters, there are a number of chemicals designed and used as RCAs. These include oleoresin capsicum (OC) and capsaicin, chlorobenzylidene malononitrile (CS), dibenz[b,f]1:4-oxazepine (CR), and chloroacetophenone (CN). The physiological and toxicological effects of RCAs are discussed in Chapters 5–7 and are briefly summarized as follows. OC and capsaicin are derived from the pepper plant. The mixture used contains the active ingredient capsaicin (8-methyl-N-vanillyl-6-nonenamide) as well as other compounds. OC is a highly effective irritant that will quickly produce lacrimation and closure of the eyes as well as respiratory responses such as bronchoconstriction, severe coughing and sneezing, shortness of breath, and nasal irritation. Other potential effects are a burning sensation on the skin and loss of motor control. Pulmonary system effects of capsaicin and capsaicinoids are dominant, including bronchospasms, respiratory arrest, and pulmonary edema. OC can also cause hypertensive crises and hypothermia. At suprathreshold levels serious respiratory and cardiovascular effects as well as permanent damage to the sensory nervous system may occur. There have been a considerable number of deaths linked to OC, although no actual causal relationship has been determined. Most of these deaths occurred within one hour of exposure (Olajos and Salem, 2001). The compound CS is highly irritating to the mucous membranes that cover or line the eyes, nose, throat, and stomach. It also causes intense eye irritation, excessive tearing, and the nose and mouth may feel a stinging or burning sensation as well as rhinorrhea. If the respiratory tract is irritated, as in frequent postexposure, the individual may also have excessive coughing and sneezing, increased tracheobronchial secretions and tightness in the chest. CS can cause death by way of serious lung injury leading to respiratory and circulatory failure. Diarrhea and vomiting will occur if the gastrointestinal tract is irritated. Burning sensation on the skin followed by inflammation and erythema are results of skin exposure. If exposure occurs in hot, humid conditions, the effects will be more severe. CS produces some or all of its effects within 30 s of exposure (Olajos and Salem, 2001). CR is a potent sensory irritant with low toxicity. The effects of CR on the eyes and skin are more transitory than with other agents. CR is not associated with contact sensitization. Experiments done on various species using various routes have shown CR to have a low acute toxicity, much less than CN or CS. Overdose in animals will cause rapid breathing, uncoordination, spasms, and convulsions. The effects generally subside gradually over a period of 15–60 min at which point the animal will either appear normal or have respiratory distress leading to death (Olajos and Salem, 2001). CN is a white crystalline solid and is also known as tear gas or Mace®. It acts directly on mucous membranes to produce intense ocular and respiratory irritation as well as burning and pain of the eye, nose, throat, and lungs. Effects can include blepharospasms (i.e. eye blinking), conjunctivitis, sneezing, coughing, secretions, nasal congestion, and a sense of suffocation. The onset of some symptoms is immediate and persist for up to 20 min after the individual leaves the contaminated atmosphere. The primary cause of death related to CN is a result of inhalation effects on the pulmonary system (Olajos and Salem, 2001).

13.2.2 Dose–response The second phase in the risk characterization framework is the dose–response assessment (see the second column of Figure 13.1). The dose–response assessment refers to the process of evaluating information on the intensity of dose required to produce the effects of interest. A key feature of the framework is its flexibility to allow for the use of the available data of varying quality. Direct, quantitative information on doses and corresponding


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% Response

responses in humans is preferred. However, if these data are lacking, then threshold data, which identify a dose at which the effect of interest is seen, could be used. If direct empirical data of either of these types is not available, then the risk analyst may consider using more qualitative information that could support an estimate of the dose–response or threshold. When dose–response data are available, one could graph the percent of individuals responding with increasing “dose” of the RCA for each level of effect as a result of the use in the situation of interest. Figure 13.2 illustrates hypothetical dose–response curves for different levels of effect. It shows the percent of individuals responding with increasing “dose” for each level. Error bars illustrate that variability in measurement of the effect(s) is expected. A single curve could also represent a combination of different effects all within a given level of severity. The dose–response curves will be used as an input (along with exposure–dose curves) to estimate the probabilities of intended and unintended effects occurring for the scenario of interest. Determining the dose corresponding to no effect is also important to help determine the effectiveness of use of the RCA. In characterizing the risk from use of these weapons, one must simultaneously consider the effectiveness of the weapon in achieving the intended effect on the target, while also considering the unintended effects on either the target or bystanders. When quantitative data are not sufficient for developing dose–response curves, threshold data may be useful. These would include point estimates (e.g. effective doses) that identify doses associated with a defined response level. This type of data could not be used to determine continuous probabilities of response as a function of dose, and are thus more limited than dose–response data. However, the threshold measure could be coupled with exposure–dose curve data to develop probabilistic estimates of the risk of reaching exposures above a defined point estimate. Point estimate data could also serve as input to the calculation of risk characterization metrics such as a margin of exposure that might help define an operational envelope for use of the RCA. Threshold type data might also be used to develop a comparative index that may provide useful information for

Mild

More severe

Very severe

Dose (exposure) Figure 13.2: Hypothetical dose–response curves for three levels of effects. “Dose” indicates the delivered dose or force (depending on type of weapon); error bars indicate expected variability in measurement of the effect (adapted from TERA, 2001).



decision-making, for example, an index to represent the ratio between the effective dose for the unintended effect to the effective dose for the intended effect. Ideally, “response” to use of RCAs would be measured as the behavioral change in the individual or crowd, such as stopping a behavior (e.g. throwing rocks), leaving the area, or lessened motivation to engage in the undesired behavior. This type of response data is rarely available, however. Lacking these direct measures of intended effect, the best substitute is to measure the physiological effects that are designed to cause the behavioral response. A difficulty in estimating effectiveness with the physical data is that significant variability exists among individuals in response to injury (based on both physiological and psychological factors), and data to quantify the differences are frequently not available. Evaluating the availability of quantitative data for the dose–response assessment helps identify research needs. Generally, if high-quality quantitative dose–response data were available for the intended and unintended effects for all potential populations, then further research is not likely to be necessary. However, because threshold data do not describe the dose–response relationship, additional research to develop dose–response data would be desirable to meet the goal of estimating probability of response. Obviously, if the data were inadequate to support any quantitative dose–response or threshold assessment, then additional research would be required. Chapters 4–11 have discussed the available toxicity information for the various RCAs. The data identified in those chapters could be used to develop the necessary dose–response information for characterizing risk.

13.2.3 Exposure assessment The third phase in the risk characterization framework is the exposure assessment (see column 4 in Figure 13.1). The goal of the exposure assessment is to quantify the dose of the RCA to the individual or population of interest. Exposure assessments use information and/or expert judgment for various exposure factors, applied to known and/or reasonably foreseeable scenarios via use of one or more exposure models (hand-calculated or software-driven). The exposure assessment includes consideration of exposure variables related to the intended and unintended effects of the agent for the targeted individuals and any bystanders, the possible hazards from exposure to the physical form of the RCA, and the possible hazards from direct exposure to components of the delivery system (e.g. blunt trauma from a canister). It is clear that the wide array of variables related to the potentially affected populations, the ambient conditions, and the scenarios in which the agent might be used to play a major role in the amount of the exposure (i.e. dose) that reaches the affected person(s). Therefore, to be most useful, exposure assessment has to be defined in terms of usage scenarios that consider the operation (e.g. crowd control, area clearance), and the geography of the site. The population of interest must also be defined; it may be the total group, a particular subpopulation, or an individual, each receiving a different dose or having a different level of vulnerability. As a first step, the scenario(s) of interest should be described. This would include evaluating the situation(s) where the RCA would be used, how the agent is delivered to the target, weather, terrain, and the size and composition of the crowd, the chemical and physical properties of the RCA’s active substance. Other considerations include how often or how much of the RCA will be used and ways in which the magnitude of exposure can be impacted by actions of the user or the affected individuals. After the scenarios are selected, relevant exposure factors are identified and data gathered and evaluated for use in the assessment. Some data gaps are likely to be identified


RIOT CONTROL AGENTS

and these might be noted and proposed as research needs. A wide array of exposure variables can play a major role in determining the concentration and ultimate dose that reaches the affected person(s), and in the effects experienced by the individual from the dose. These factors can be grouped into four categories: scenario factors, physical form of the agent and delivery system, individual factors, and interindividual factors. Examples of potentially relevant exposure variables are described next.

Scenario factors (variables) The setting in which an RCA is used will greatly impact the amount of exposure to individuals. Weather-related factors are very important for assessments of RCAs. For example, the wind direction and speed will impact the delivery of the agent to the target area (or to unintended areas), and will be important factors in the onset time and duration of the responses of the targets and any bystanders. Geographic features such as hills, trees, fences, or buildings between the user and the effected people need to be considered as factors important in assessing the delivery, dispersion, and dilution of the agents. Assessment of the temperature, humidity, fog, mist, or rain can also be important. For example, sweaty or moist skin can be more responsive to the pain, burning, or discomfort associated with some of these chemicals. Moist skin may also lead to formation of other compounds whose toxicity must be considered (e.g. 2-chlorobenzaldehyde and malononitrile can be produced via hydrolysis when a moist skin is exposed to the riot control agent CS) (Rietveld et al., 1988).

Physical form of the RCAs and delivery RCAs can be delivered in various forms, including powders or aerosols delivered by various types of dispersal systems. Delivery might be from a burning or bursting grenade, from a device thrown by hand or delivered by a grenade or rocket launcher, or by release from a helicopter or airplane flying overhead. Further, delivery could be from a handheld or carried pressurized container pointed at a targeted individual or crowd. Other factors to consider include the design range of the system, the diameter, weight, and compliance characteristics of any canisters or projectiles, and the reliability and consistency of operation of the delivery system.

Individual factors Individual factors can include an individual’s breathing rate (the of air inhaled per breath under various exertion and emotional levels), height, the ability to metabolically activate, deactivate, and excrete an agent, and the individual’s degree of sweating for various body locations (e.g. exposed skin on face and arms) under various exertion and emotional levels. Other individual factors include personal psychology, motivation, and physical conditions, the use of any countermeasures (e.g. goggles or respiratory protection), type of clothing (e.g. long-sleeved shirts and pants compared to clothing that leaves more skin exposed), activity factors such as the distance of the individual from the user of RCA, and behavior such as whether the target or bystander is immobile or advancing during the duration of the event. Individuals may also try to decontaminate themselves by washing their skin and clothing with water, or soap and water.

Interindividual factors Interindividual factors encompass the characteristics of the group of individuals (targets and bystanders), including group distributions for the various individual factors noted. Also potentially useful in the assessment is knowledge of scenario-specific crowd



characteristics and dynamics such as the crowd size and density, the age distribution, and whether the individuals as a group or in subsets are likely to remain immobile, advance, or turn away or flee in response to various uses of the RCA. One must gather quantitative data to assess the impact of each of these variables on the dose received by the individual or population of interest. This includes both attenuation of delivered dose and factors that affect the probability of being hit or exposed. While the intended effects of most RCAs are sensory irritation at the site of contact, there is also the possibility of systemic effects and possible biotransformation and hydrolysis products that should be considered. The exposure assessment could estimate the amount of systemic exposure via inhalation, absorption through the skin, and ingestion, using published approaches for RCAs and other chemicals. Skin or eye penetration, burns, and impaired lung function have been noted as the possible more prolonged effects by Hu et al. (1989) and the US Army Medical Research Institute of Chemical Defense (1995), as well as longerterm systemic effects (e.g. NTP, 1990). The hydrolysis of CS to 2-chlorobenzaldehyde and malononitrile on moist skin, followed by the possible dermal uptake and excretion of o-chlorobenzaldehyde and its metabolites has been studied (Rietveld et al., 1988), and the reader is referred to Chapter 4 and papers by Rietveld et al. (1983) and Brewster et al. (1987) regarding the systemic metabolism of CS. An important component to consider in assessing exposures to RCAs is the duration of exposure. For example, the “burning” and pain of exposed mucous membranes and skin, the eye pain and tearing, the burning in the nostrils, respiratory discomfort, and tingling of the exposed skin can occur within seconds of exposure, but seldom persist beyond several minutes after exposure has ended (e.g. US Army Medical Research Institute of Chemical Defense, 1995). The duration of exposure is often limited as the affected individuals seek to escape from the exposure. For example, the user of the RCA can try to control how much and how quickly the agent is dispersed to reach the desired air concentration and achieve the intended crowd control effects. However, the user can decide how long the desired concentration should be maintained, and to control duration by further release of the agent at the same location or while moving into, away from, or alongside the crowd, or while flying above the crowd. The duration of exposure can also be partially controlled by conditions limiting the ability for the individuals to escape the exposure, and/or the ability of the agent to be diluted in the air. The information for the exposure factors judged to be most relevant for the exposure assessment of interest is then used to model the affected individuals for the scenarios of interest. Probabilistic estimates of risk for a given scenario and its exposure conditions can then be developed, as data allow. Individual exposure–dose curves describing the quantitative relationship between dose (or concentration) and a particular variable of interest as hypothetically illustrated in Figure 13.3. Separate graphs plotting the relationship between the dose or concentration and each individual variable of interest could be developed, resulting in multiple graphs. If data and appropriate models were available, one might model the impact of the multiple variables of interest and draw one curve (as shown by the dashed curve in Figure 13.3). For RCAs, concentration of the agent might be a common metric for relating the exposure factors to the dose–response. In a situation where no quantitative data are available to relate the important variables to exposure intensity, a point estimate of exposure could be developed based on qualitative information and expert judgment, in a similar fashion as for dose–response. Use of these estimates would result in a lesser degree of certainty in the resulting risk characterization. If data on exposure factors are not sufficient to make a defensible estimate, additional research is required. Additional research may also be useful to reduce uncertainty in quantitative estimates of exposure. The output of the exposure model(s) can be used to assess the impact of each of the exposure factors on the exposure received by the individual or population of interest.


Dose

RIOT CONTROL AGENTS

Single variable

Multiple variable

Distance Figure 13.3: Quantitative relationship between dose and variable(s) of interest

(hypothetical). The solid line represents the relationship between dose and a single variable of interest (distance, in this hypothetical example); error bars indicate expected variability in measurement and/or probability of a hit. The dashed line reflects the change in dose by distance incorporating the impact of additional variables (note that error bars get larger because of additional measurements) (adapted from TERA, 2001).

Sensitivity analysis can be used to identify the exposure factors and data impacting the exposure estimate the most, and those that make no meaningful difference. Availability of high quality data for the various types of exposure factors associated with an RCA scenario will help develop an exposure assessment with minimal uncertainty. If models are used to estimate exposure, the limitations of the model should be understood and highlighted as part of the risk characterization.

13.2.4 Risk characterization The final step of the framework is risk characterization, the integration of information on dose–response with the estimates of exposure, resulting in estimates or probabilities of effects occurring in the population of interest. The form of the risk characterization will depend upon the availability and quality of the data used for the dose–response and exposure assessments. The framework document (TERA, 2001) presents two alternative approaches for representing the potential degree of risk. A probabilistic approach can be used when there is adequate quantitative dose–response and exposure–response data, while a margin of exposure approach is more useful when quantitative dose–response data are lacking, but threshold or point estimate data are available. Ideally, the risk characterization will provide the decision-maker with the probability of occurrence of intended and unintended effects given a defined set of variables. Multiple scenarios could be considered and the results are likely to differ. Depending on the specific techniques used, the results might also be presented for different populations of interest (user, bystander, or target) or as a combined probability for all affected populations.



Similarly, the data may be amenable to combining a series of effects (perhaps of similar severity) into a single curve to represent the probability of any of the grouped effects occurring to the population of interest. For RCAs, risk could be characterized as the probability of a particular effect or group of effects occurring with a particular number of shots of a canister of an RCA into a specified crowd. In such cases, the resulting risk characterization might look like that shown in Figure 13.4. However, in some cases, the data will not be sufficient for developing curves for the dose–response or the exposure–dose relationship. An alternative is to use threshold type information to plot the likelihood of an effect occurring given a particular exposure scenario. If only point estimates are available for dose–response and exposure estimates, then one might use these data to calculate a margin of exposure which is computed as the ratio of the dose (or concentration) that produces an effect of interest at a predetermined response rate (e.g. the ED50 or ED90) to the estimate of the dose that will be delivered to the person/population of interest. The value of this approach is that it provides a sense for the degree of difference between the exposure for a given scenario and the amount of exposure that would cause the intended and unintended effects to occur. Selection of the effective dose is likely to be different for intended and unintended effects. Figure 13.5 shows estimates of RCA concentration for three different scenarios and the EC90 for lacrimation (a possible intended effect) and EC10 for pulmonary edema (a possible unintended effect). The shading between these two threshold values might illustrate an operational envelope, within which the intended effect is achieved and the unintended effects are below a level of concern given a particular situation. In this hypothetical example, only the exposure concentration for Scenario A falls within the shaded area. The format for presenting the output of the risk characterization will vary based on the needs of the decision-maker and quality and quantity of data. However, it is very important to accompany any graphic or numeric representations of risk with a thorough

100

Undesired effects

80

% Response

Intended effects 60

40 No effects 20

0 0

1

2

3

4

5

6

7

8

9

10

Number of canisters shot Figure 13.4: Risk characterization based on number of canisters shot into crowd

(adapted from TERA, 2001).


RIOT CONTROL AGENTS

EC10 pulmonary edema

Concentration (a.u.)

25

15

EC90 lacrimation

5 A

B

C

Scenarios Figure 13.5: Concentration as a function of three hypothetical scenarios and the

resulting exceedence (or not) of important thresholds (adapted from TERA, 2001).

discussion of the appropriate interpretation of the risk measures that are presented. The risk characterization would describe assumptions and uncertainties used in the analysis. Sensitivity analysis should be provided when possible. The overall level of confidence in the risk estimates and critical areas of uncertainty should be discussed.

13.3 CONCLUSIONS A framework for characterizing risk and effectiveness of NLW can be applied to situations involving use of RCAs (TERA, 2001). Utilizing this framework, a risk analyst could evaluate the available data on dose–response for the effects of concern from the RCA of interest, evaluate the exposure scenario to best describe the conditions for use and resulting exposure estimates, and combine these results to generate estimates of probability of the specified effects occurring in the population of interest. The resulting estimates of effectiveness and risk will reflect the quality of the underlying data.

REFERENCES BREWSTER, K., HARRISON, J.M., LEADBEATER, L., NEWMAN, J., and UPSHALL, D.G. (1987) The fate of 2-chlorobenzylidene malononitrile (CS) in rats, Xenobiotica, 17: 911–924. HU, H., FINE, J., EPSTEIN, P., KELSEY, K., REYNOLDS, P., and WALKER, B. (1989) Tear gas harassing agent or toxic chemical weapon?, Journal of the American Medical Association, 262(5): 660–663. NAS (National Academy of Sciences) (1983) Risk Assessment in the Federal Government: Managing the Process, Washington, DC: National Academy Press. NAS/NRC (1994) Science and Judgment in Risk Assessment. Washington, DC: National Academy Press, National Academy of Sciences/National Research Council. NTP (National Toxicology Program) (1990) Toxicology and Carcinogenesis Studies of CS2 (94% O-Chlorobenzalmalononitrile)(CAS No. 2698-41-1) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). NTIS-PB90256280.



OLAJOS, E.J. and SALEM H. (2001) Riot control agents: pharmacology, toxicology, biochemistry and chemistry. Journal of Applied Toxicology, 21(5): 355–391. RIETVELD, E.C., DELBRESSINE, L.P.C., WAEGEMAEKERS, T.H.J., and SEUTTER-BERLAGE, F. (1983) 2-Chlorobenzyl-mercapturic acid, a metabolite of the riot control agent 2-chlorobenzylidene malononitrile (CS) in the rat, Archives of Toxicology, 54: 139–144. RIETVELD, E.C., HOET, R.M., SEUTTER-BERLAGE, F., and VAN ROSSUM, J.M. (1988) Precutaneous absorption of Carbon-14 Labeled 2-Chlorobenzaldehyde in Rats Metabolism and Toxicokinetics, European Journal of Metabolism and Pharmacokinetics, 13(4): 231–240. TERA (2001) Risk Characterization of Non-Lethal Weapons Report on Expert Workshop and Proposed Conceptual Framework. Submitted to Veridian Engineering. October 5, 2001. US Army Medical Research Institute of Chemical Defense (1995) Medical Management of Chemical Casualties Handbook, Second Edition, Chapter on Riot Control Agents – CS and CN, Chemical Casualty Care Office, Aberdeen Proving Ground, MD 21010–5425, http://www.fas.org/nuke/ guide/usa/doctrine/army/mmcch/RiotAgnt.htm


CHAPTER

Occupational Exposures to Riot Control Agents

14

WOODHALL STOPFORD Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, North Carolina

14.1

EXPOSURES

Occupational exposures to riot control agents (RCAs) occur during the production and packaging of these agents, during training exercises where officers are exposed intentionally and during their operative use. There are published accounts of worker exposure to 1-chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS) and oleoresin capsicum (OC) but not to dibenz[b,f]1:4-oxazepine (CR) or n-nonanoyl vanillylamide (VAN). CR has been developed as an RCA and VAN is used by the police forces of at least four countries in personal defense sprays (Independent Police Commission of Northern Ireland, 2001). The use of personal defense sprays that have a high content of respirable particles can result in exposures to officers sufficiently high to cause as many symptoms as in those on whom the sprays are used. In this regard, Kock and Rix (1996) studied the use of CS by 3,818 police officers in 16 forces over a period of six months. CS was used 726 times. Officers using CS (78%) were cross-contaminated and experienced symptoms of burning to skin (49%), pain or discomfort to eyes (45%), breathing difficulties (7%), throat irritation (2%), and nasal irritation (3%). Symptom frequency experienced by those being sprayed was similar to those of police officers with 37% having burning to skin, 68% pain or discomfort to eyes, 16% breathing difficulties and 16% having no effects. Published accounts of worker exposures to RCAs are reviewed in the following sections. Occupational exposures to workers have been associated with problems that were similar to those seen with human exposures to RCAs under controlled conditions (see Chapter 11) and, sometimes, were more severe with skin burns, allergic dermatitis, and pulmonary edema.

14.2

CN

Exposures to CN have been described during its manufacture, training, and use. Calnan (1979) described a man who developed a rash after working in a factory making CN powder. He wore protective clothing including coveralls, rubber gloves, and air supplied respirator. After seven weeks, he developed swelling and redness of face, trunk, arms, and legs. The rash cleared up in few weeks when away from work. Patch testing with 1% CN resulted in an eroded oozing area. Several control subjects tested with the same patch test


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technique experienced redness but no comparable reactions. Kibler (1933) describes a similar reaction that developed in three workers who had worked around CN for several years. He considered that the dermatitis was probably allergic in nature. Madden (1951) reviewed a case described by Kissen and Mazer (1944) where a soldier who had no reaction after his first exposure to CN developed a mild dermatitis within 30 h that lasted four days after a second exposure. Within 10 h of a third exposure he developed a generalized dermatitis that lasted 10 days. Patch testing gave strongly positive reactions and produced a flare of the original dermatitis. This was the only allergic reaction among more than 10,000 exposures at their station. Queen and Stander (1941) describe an allergic reaction that developed in a 43-year-old recruit who went through a CN training chamber routine, being in the chamber for 5 min and removing his mask during exposure. He had been exposed to CN 17 years previously, also during a training exercise. At that time he had experienced slight itching. Within 5 min of this most recent exposure, he developed a generalized itching that became progressively worse over the next few hours. Four hours after exposure he had a diffuse and intense redness over his entire body except for his feet (he was wearing boots) and a portion of his face that was covered with his mask. By 48 h after exposure the rash became vesicular and later severe subcutaneous edema and severe itching developed. Profuse desquamation started on the sixth day after exposure. Leenutaphong and Goerz (1989) describe a case where a police officer accidentally discharged a CN spray canister that he kept in his pant pocket. A localized redness and a burning sensation occurred instantly and he immediately washed the site with water for 5 min. A blistering reaction developed within two days. After two weeks the borders had extended. The rash persisted for four weeks. Patch testing one month later was positive for CN. In a similar incident, Goh (1987) noted that a prison guard was accidentally exposed to CN when a tear gas canister leaked. He developed an allergic contact dermatitis. Ingram (1942) described an officer exposed to high concentration of CN for 45 min in a confined space. After 6 3/4 h, later he noted irritation of skin followed in 15 min by a morbilliform eruption which soon became blistered. Large blisters developed in his groin and under his arms and a rash with associated subcutaneous edema was widely spread on his trunk and extremities. The rash resolved within two weeks. The rash recurred with minor reexposures.

14.3 CS Occupational exposures to CS with associated adverse effects have occurred during its manufacture, during training exercises and when used in police actions. Reactions have included skin burns, allergic skin reactions, and chest effects. Shmunes and Taylor (1973) evaluated 28 workers manufacturing CS2. Air levels to CS in this plant ranged from 0.64 to 12 mg/m3. Twenty-five complained of skin rashes and two had allergies to CS confirmed on patch testing to a 0.1% CS solution. Factory workers who have become sensitized developed an eczematous reaction of the face with reexposure. In 21 of the 25 workers with rashes, the dermatitis developed during warm weather. Nine employees developed dermatitis during the survey: seven had an acute bullous contact dermatitis indicating a severe irritant reaction. Typically when a rash occurred, there was redness by end of work shift. By 48 h blisters usually had developed and the redness had faded. By 72 h the blisters had broken leaving crusted erosions. These would slowly heal over the next two weeks leaving inflammatory hyperpigmentation. The only chest symptoms that were seen occurred in an employee who did not wear a respirator: he developed wheezing and redness of face. The highest exposures to CS aerosol occurred while filling plastic bags and this was where dermatitis was likely to


OCCUPATIONAL EXPOSURES TO RCA

occur. Risk factors for dermatitis included increased environmental temperature, high level exposures, inadequacy of protective clothing, and inadequate safety procedures. The authors describe CS being manufactured at another facility where workers were not allowed to disrobe during the workday. Workers wore disposable paper coveralls over work coveralls and went through a decontamination facility at end of each workday. Only 2 of approximately 100 workers developed second and third degree burns. These were, however, severe enough to require hospitalization. Bowers et al. (1960) describe the manufacture of CS at Edgewood Arsenal. During a 10 month period 11 workers developed rashes. Workers wore air-supplied suits and respirators while in production areas. One worker developed a minor rash after two weeks of work. After a second incidental exposure while in his street clothes, an extensive bullous rash developed within two days, requiring three weeks of hospitalization. Vesicular rashes also occurred in 10 other workers. In three either a generalized rash or one affecting the same areas as the original rash occurred with reexposure, even when exposures were incidental. The authors note that heat and humidity or sweating increased the likelihood of a reaction. Gutentag et al. (1960) noted that several persons who were working with CS in the manufacturing plant developed minor epistaxis that was non-recurring. Himsworth et al. (1971) describe three scientists working with CS at Porton. One became sensitized after repeated exposures: with each exposure he would develop redness of skin and conjunctivitis. They further describe illnesses that occurred at a CS manufacturing facility employing 22 workers, only four of whom had direct contact to CS. Wearing of protective clothing was rigidly enforced. During the previous 11 years, eight workers developed CS-related skin rashes and two had acute work-related bronchitis. The mortality experience among past workers at this plant was also investigated. No excess mortality was found when death rates were compared to those of the general population. They further report on the evaluation of ventilatory capacity of workers exposed to CS. Researchers measured vital capacity, forced expiratory volume, and peak flow. No changes in ventilatory capacity were found either acutely or in the long term as a result of exposure to just tolerable or barely detectable amounts of CS. CS is used as a self-defense spray in the United Kingdom. Jones (1997) noted that during a training exercise with CS sprays, an inspector received blisters to 40% of one eye and 50% of the other. Because of training-related health effects, the practice of spraying officers was stopped. Thomas et al. (2002) report on nine soldiers who developed chest problems after being exposed to CS for a few seconds to several minutes during a training exercise. Symptoms appeared 36–84 h after exposure during intense physical training. Initial symptoms included hemoptysis (5), cough, (9) and shortness of breath (9). Four of nine had hypoxia and infiltrates were found in four consistent with pulmonary edema. Signs and symptoms resolved within 72 h of the hospital admission. One week after CS exposure, all nine soldiers demonstrated normal lung function during spirometry done before and after exercise. With recreation of the event, the maximum CS level was 17 mg/m3. Weigand (1969) describes the effects of CS exposures to soldiers during a field exercise. Temperatures and humidity were high and it was raining. Protective masks were worn. Soldiers were exposed to high concentrations of CS1 aerosol. Some decontaminated with water and some changed their clothes 2 h after exposure. After 14–16 h, blistering occurred in all men who had not hosed off or changed clothes. Kock and Rix (1996) reviewed 257 medical reports of police officers who had incidental exposures to CS when using personal defense sprays during arrests. Of these, 30% required decontamination. No further treatment was advised in 90% of cases. Twelve police officers had preexisting asthma. There was nothing to suggest that they reacted any differently from those without asthma.


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Weigand (1969) noted that firemen entering burning or burned out buildings where CS had been used became exposed when CS was re-aerosolized by their movements or by the force of water from their hoses. They developed redness and edema in exposed areas of their faces and necks.

14.4 OC OC is processed from chili peppers. Workers handling chili peppers or manufacturing chili powder have experienced OC-related effects. Effects have also been seen in officers intentionally sprayed with OC. Vogl (1982) describe “Hunan hand” occurring among workers along the Mexican border. These workers developed a severe dermatitis called “Hunan hand” when processing chili peppers. Burnett (1989) ascribes the term to a syndrome of skin irritation, redness, and burning pain seen in Chinese workers who process chili peppers. Blanc et al. (1991) evaluated workers chronically exposed to hot chili (capsicum) pepper powder: 22 capsicum-exposed and 19 nonexposed workers were evaluated with pulmonary function tests. Thirteen (59%) of the capsicum-exposed workers reported cough as compared to four (21%) of the nonexposed workers ( p 0.05). Workers also complained of more chest discomfort or tightness, shortness of breath, stuffy, or runny nose but fewer problems with sinus trouble than controls. Baseline pulmonary function studies of flow and volume did not differ between the two groups. Chan et al. (1990) evaluated 61 male spice grinders from 14 factories to determine if they had any skin or respiratory symptoms associated with their work. All subjects were interviewed and examined. Symptoms of upper respiratory tract irritation, such as sneezing and runny nose, were experienced during work by 49%. Over 26% experienced a warm or burning sensation of the skin when grinding chili peppers. There was no evidence of allergic skin disease or asthma. Uragoda (1967) notes that the majority of the workers in chili grinding mills suffer from sneezing, watering of the nose, and cough. A burning sensation of the skin occurs, especially when skin is moist. He found that most workers complained of sneezing (95%), rhinorrhea (95%), cough (95%), and a burning sensation of skin, primarily when skin is moist (95%). Eleven percent also noted chest tightness. Uragoda (1983) evaluated 12 chili grinders clinically. All complained of cough, sneezing, and rhinorrhea while one complained of coughing up blood when first starting to work but not for the ensuing 11 years of employment. Skin tests to a chili antigen were negative in eight subjects. Chest X-rays were normal. Lankatilake and Uragoda (1993) later evaluated the respiratory function of workers in five chili factories in Sri Lanka. When first employed, 60% of workers experienced symptoms of cough, sneezing, watering nose; 44% developed chronic respiratory symptoms including a chronic cough and shortness of breath on exertion. Workers (25 of the 26) in these factories received pulmonary function studies. There were no changes in flows and volumes pre or postshift on Mondays with values similar to those of a control population. Polla and Lacroix (1993) evaluated a 52-year-old woman who developed recurrent episodes of chest tightness and shortness of breath after changing her workplace in a perfume factory to one where she now handled capsaicin. Peak flows during one episode were reduced. A simulated manipulation of workplace materials showed no effects except when handling capsaicin where she developed rhinorrhea and sneezing. Weaver and Jett (1989) describe the effects on 828 FBI trainees who were sprayed with either 1% or 5% OC during training exercises. Trainees experienced severe twitching of the eyes and involuntary closing of the eyes; respiratory inflammation with coughing,



TABLE 14.1 Conditions requiring acute medical care after OC spray exposures during training Condition

Number affected (of total of 61)

Eye irritationa Chest symptomsb Nose/eye/throat symptoms Skin effectsc Hypertensiond Headachee Cardiovascular effectsf Loss of consciousness Hyperventilation

28 20 7 5 11 16 2 2 3

Notes a One described as an eye burn where five days were lost from work. b One with an allergic respiratory reaction and four with asthmatic responses. c Includes two cases of uriticaria. d Blood pressure 180/110 in one case and 200/110 in a second. A 12th case had hypertension noted after epinephrine treatment. e Described as severe in nine. f EKG changes in one, chest pain requiring nitroglycerin in a second.

shortness of breath, gasping of breath, and gagging; skin inflammation with a burning sensation and redness of the skin; nausea and catatonia. A feeling of tightness in the chest was often accompanied by a feeling of panic. Finds included nasal discharge and blisters of skin from very heavy exposures. A report (Zarc International, 1990) described the effects on 899 FBI trainees who were exposed to 1% or 10% OC aerosol grenades. Exposures lasted for 10–20 s in most cases, with a maximum exposure time of 45 s. Symptoms associated with exposure included stinging of the eyes, lachrimation and severe blepharospasm; shortness of breath, coughing and gasping; and skin redness. Temporary paralysis of larynx occurred in some individuals being unable to talk and emitting only gasping noises. Smith and Stopford (1999) investigated medical complaints of correction officers sprayed with OC spray during training exercises between February 1993 and August 1995. A total of 61 officers of approximately 6,000 who were exposed during that period received medical care. Officers received medical attention for eye effects including conjunctivitis, keratitis, eye burns, corneal abrasions, conjunctival blistering, swelling of the lids and allergic reactions; airway symptoms including shortness of breath, asthma attacks, chest pain, and nose irritation; and other medical problems including acute hypertension, severe headaches, EKG changes, and loss of consciousness. The incidence of effects that were sufficiently severe to require medical attention ranged from 1% for the group as a whole to 5% among one group of 187 officers undergoing training. Problems encountered during training are detailed as follows (Table 14.1). Adverse effects persisted for more than one week in 13% of trainees receiving medical care and included eye problems (3), chest problems (3), and headaches (2). One of the trainees with persistent headaches also had problems with disorientation.


RIOT CONTROL AGENTS

14.5 REGULATORY STATUS AND WORKER PROTECTION The departments of labor in several states have been concerned about intentional exposure of police and correction officers to OC spray during training exercises and have issued regulations to limit occupational exposures to OC spray. A review of these regulatory actions follows. Prior to 1996 correction officers in North Carolina were required to be exposed to OC spray during training exercises. In 1995 the Division of Epidemiology of the NC Department of Health and Human Services and the Occupational Safety and Health Section of the NC Department of Labor began to investigate training practices involving intentional exposure to OC. Based on a compliance inspection, observation of a training session, and a detailed review of various training programs and OSHA activities outside of NC, they concluded that exposure to OC during training constituted an unacceptable risk (Smith and Stopford, 1999). This assessment resulted in recommendations by the Department of Labor to the Department of Corrections to conduct OC training exercises that included the following components: 1 2 3 4 5

Use of indirect OC spray exposure. Establishment of a medical screening program to identify employees with health conditions that may be exacerbated by exposure to OC spray. Evaluation of accommodation requests should be conducted by a trained health professional. Hazard communication training to include a discussion of health effects experienced by employees during direct exposure. Minimize exposure training during cold weather to reduce the possibility of hypothermia during decontamination.

In 1997 delegates to the NC Medical Society’s annual meeting adopted a resolution calling for the NC Commissioner of Labor to issue guidelines for the safe use of capsaicin during training exercises by both correction and police officers. To reduce the chance of serious injury they recommended the substitution of indirect spraying, the provision of chemical goggles if direct spraying is used, screening employees to identify and exempt those who might have health conditions that might be exacerbated by OC exposure, having medical personnel present during training to render first aid or medical treatment if necessary, and complying with OSHA’s Hazard Communication (29 CFR 1910.1200) and Personal Protective Equipment (29 CFR 1910.132) standards during each OC spray training exercises (Smith and Stopford, 1999). In addition to North Carolina, state occupational and health divisions for Utah and Tennessee have issued similar recommendations. Utah requires the following during OC spray exposures during training exercises involving police officers: 1 2

protective eye and face equipment; training to include physical health hazards of OC spray and protective methods in compliance with OSHA’s Hazard Communication Standard.

After these regulations were adopted, training of police officers was changed so that exposures are now done with an inert spray. The Tennessee Department of Labor requires the following during training exercises involving OC spray: 1 2

trainees should wear face shields or chemical goggles; an emergency shower and eye wash station should be provided;



3 4 5

medical screening of trainees and trainers to identify those susceptible to effects of the spray; medical personnel on site to render first aid and medical treatment; training in compliance with OSHA’s Hazard Communication Standard.

Occupational exposure during training is not advised and those who continue to use it should exempt entirely all employees who are at an increased risk of adverse effects including those with corneal disease, hypertension, heart disease, respiratory infections, bronchitis, asthma, a history of airway reactivity following irritant exposures and cigarette smokers (Stopford and Smith, 1999). NIOSH (1995) recommends the following actions to limit adverse effects associated with the manufacture of RCAs. Process enclosure with local exhaust ventilation, general dilutional ventilation and personal protective equipment should be used to control worker exposures. Workers should receive training to include information on hazards and early detection of adverse effects. Workers should receive medical evaluations prior to job placement, periodically during term of employment and at the time of job transfer to include a medical, environmental, and occupational history, a physical examination, physiological tests of the function of eyes and pulmonary function studies. They recommended no biological monitoring or blood studies. Workers should thoroughly wash hands, forearms and face with soap and water before eating, using tobacco products, using the toilet, or applying cosmetics. Respirators must be worn before engineering controls have been installed, during work operations such as maintenance or repair activities that involve unknown exposures, during operations that require entry into tanks or closed vessels, and during emergency situations. A respiratory protection program should be instituted that complies with OSHA’s respiratory protection standard, 29 CFR 1901.134, to include the evaluation of the ability of a worker to work while wearing a respirator, regular training, fit testing, workplace monitoring, respirator maintenance, inspection, and cleaning. Personal protective equipment should include chemical protective clothing and safety glasses, goggles, or face shields. Eyewash fountains and emergency showers should be available. Contact lenses should not be worn.

REFERENCES BLANC, P., LIU, D., JUAREZ, C., and BOUSHEY, H.A. (1991) Cough in hot pepper workers, Chest, 99(1): 27–32. BOWERS, M.B., OWENS, E.J., and PUNTE, C.L. (1960) Interim Report of CS Exposures in Plant Workers. CWL Technical Memorandum 24–50, Army Chemical Center, MD. BURNETT, J.W. (1989) Capsicum pepper dermatitis, Cutis, 43(6): 534. CALNAN, C.D. (1979) Chloracetophenone dermatitis, Contact Dermatitis, 5(3): 195–196. CHAN, O.Y., LEE, C.S., TAN, K.T., and THIRUMOORTHY, T. (1990) Health problems among spice grinders, Japanese Society of Occupational Medicine, 40(3): 111–115. GOH, C.L. (1987) Allergic contact dermatitis to mace tear gas, Australian Journal of Dermatology, 28(3): 115–116. GUTENTAG, P.L., HART, J., OWENS, E.J., and PUNTE, C.L. (1960) The Evaluation of CS Aerosols as a Riot Control Agent in Man. US Army Chemical Warfare Laboratories, Technical Report CWLR 2365 Army Chemical Center, MD. HIMSWORTH, H., BLACK, D.A.K., CRAWFORD, T. et al. (1971) Report of the enquiry into the Medical and Toxicological aspects of CS (Orthochlorobenzylidene Malononitrile). Part 11. Enquiry into Toxicological aspects of CS and its use for Civil Purposes. CMnd. 4775. Home Office, 1971. INDEPENDENT COMMISSION ON POLICING FOR NORTHERN IRELAND (2001) Patten Report Recommendations 69 and 70 Relating to Public Order Equipment. A Research Program into Alternative Policing


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Approaches towards the Mangement of Conflict, December 2001, http://www.nio.gov.uk/ pdf/phase2rep.pdf INGRAM, J.T. (1942) Dermatitis from exposure to tear gas, British Journal of Dermatology, 54: 319–321. JONES, G.R. (1997) Are CS sprays safe? The Lancet, 350(9078): 605–606. KIBLER, A.L. (1933) The after-effects of chloracetophenone. Edgewood Arsenal, MD: Medical Research Laboratorires, EATR 133. KISSEN, M. and MAZER, M. (1944) Cutaneous hypersensitivity to tear gas (chloroacetophenone). Bull US Army Med Dept No. 81, pp. 120–121, 1944 as referenced in MADDEN, J.F. (1951). KOCK, E. and RIX, B. (1996) A Review of Police Trials of the CS Aerosol Incapacitant. Police Research Series Paper 21. Police Research Group. London: Home Office. ISBN 1–85893–758–2. LANKATILAKE, K.N. and URAGODA, C.G. (1993) Respiratory function in chilli grinders, Occupational Medicine, 43: 139–142. LEENUTAPHONG, V. and GOERZ, G. (1989) Allergic Contact Dermatitis from Chloroacetophenone (Tear Gas). Contact Dermatitis, 20: 316. MADDEN, J.F. (1951) Cutaneous hypersensitivity to tear gas (chloroacetophenone). A case report Archives of Dermatology and Syphilology, 63: 133–4. NIOSH (1995) Occupational Safety and Health Guidelines for Chemical Hazards, Supplement IV OHG, PB96134549. POLLA, B.S. and LACROIX, J.S. (1993) Capsaicin in the workplace, Allergy, 48: 550. QUEEN, F.B. and STANDER, T. (1941) Allergic dermatitis following exposure to tear gas (chloroacetophenone), Journal of the American Medical Association, 117: 1879. SHMUNES, E. and TAYLOR, J.S. (1973) Industrial contact dermatitis. Effect of the riot control agent ortho-chlorobenzylidene malononitrile, Archives of Dermatology, 107: 212–216. SMITH, C.G. and STOPFORD, W. (1999) Health hazards of pepper spray, North Carolina Medical Journal, 60(5): 268–274. THOMAS, R.J., SMITH, P.A., RASCONA, D.A, LOUTHAN, J.D., and GUMPERT, B.(2002) Acute pulmonary effects from o-chlorobenzylidenemalonitrile “tear gas”: A unique exposure outcome unmasked by strenuous exercise after a military training event, Military Medicine, 167(2): 136–139. URAGODA, C.G. (1967) Symptoms among chilli grinders, British Journal of Industrial Medicine, 24: 162–164. URAGODA, C.C. (1983) A comparative study of chili grinders with paprika splitters. Japanese Society of Occupational Medicine, 33(3): 145–147. VOGL, T.P. (1982) Treatment of Hunan hand, New England Journal of Medicine, 306: 178. WEAVER, W. and JETT, M.B. (1989) Oleoresin Capsicum Training and Use. Quantico, VA: Federal Bureau of Investigations Academy, Firearms Training Unit (FTU). WEIGAND, D.A. (1969) Cutaneous reaction to the riot control agent CS, Military Medicine, 34: 437–440. ZARC INTERNATIONAL (1990) Preliminary FBI Report on Cap-Stun II Aerosol Subject Restraint. International Cap-Stun Training Center.


CHAPTER

Risk Management and Public Health Considerations of Riot Control Agents

15

VERONIQUE D. HAUSCHILD US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland

15.1 INTRODUCTION Modern day riot control agents (RCAs) (e.g. the “tear gases” chloroacetophenone (CN) (marketed as Mace®) and o-chlorobenzilidene malononitrile (CS), dibenz[b,f]1:4oxazepine (CR), and “pepper sprays” containing oleoresin capsicum (OC) or “synthetic” capsaicin (nonivamide) are a unique category of chemicals that are specifically designed to produce acute site-specific physiological actions on the eyes, upper respiratory tract, and skin of humans (and animals). Some groups categorize these chemicals as chemical warfare agents and even see their use as contrary to the Geneva Protocol CWC Treaty (Aftergood, 1994). However, other groups specifically do not include RCAs in their definition of warfare agents (DTRA, 2001) because of their routine application by nonmilitary personnel in civilian environments. The particular uniqueness of RCAs is that despite their intentional use to cause some degree of physiological deficit so as to temporarily “incapacitate” or debilitate adversarial persons, the greater intention of their use is to prevent or minimize injury and death. Specifically, by providing less-than-lethal ‘minimal force’ alternatives for controlling and managing adversarial groups and individual(s), RCAs have proven to be an increasingly desired public health and safety tool for both law enforcement agencies as well as private citizens. However, as with the beneficial use of a variety of chemicals utilized in our society for enhancing public health and quality of life – from pesticides to pharmaceuticals – it is inherently necessary that the potential adverse impacts be identified, assessed, and properly managed to ensure that the benefits suitably outweigh the risks. The health risks associated with the appropriate use of current RCAs, as a whole, may be considered relatively minimal. But potential risks exist, particularly in scenarios that may result in uniquely high concentrations, extended durations of exposure, or in situations involving susceptible persons. In addition, the risks associated with the increasing array of formulations and mixtures – as well as varying potencies of OC products, may also be associated with increased incidence of unintended effects. These risks include potential permanent eye injury, skin damage or sensitization, nasal desensitization, respiratory tract damage such as reactive-airways dysfunction syndrome (RADS), potential developmental and mutagenic/carcinogenic impacts, and even in some cases death.


RIOT CONTROL AGENTS

Appropriate public health risk management goals should be to minimize these risks. Unfortunately, currently available information and guidance on the risks and necessary controls associated with RCA formulations and devices is incomplete and confusing. This stems in part from lack of regulatory oversight of these products. To the extent that current data allows, the hazards associated with the active ingredients and types of dispersal mechanisms and solvents are described in various chapters of this book, but the true risks associated with real life exposures to the increasing mixtures available are not clearly known as actual exposures and adverse outcome are not tracked and assessed for true epidemiological evaluation. This chapter examines some of the shortfalls of existing public health processes and mandates for managing the risks associated with RCA devices, examines the specific public needs and benefits addressed by the availability of such items and substances, summarizes key health risks, and proposes a strategy to better manage these risks in the context of public health goals. Actions identified could minimize the unintended health risks associated with today’s increasing RCA use by law enforcement personnel and the public while maximizing their benefits to society.

15.2 PUBLIC HEALTH GOALS, RISK MANAGEMENT, AND REGULATORY PROCESS Particularly in today’s complex and industrialized society, the reduction or elimination of one risk often involves the acceptance of another type of risk. The process of determining which risks to accept, mitigate, or control is risk management. Risk management is used for a variety of end goals, including financial, quality of life, and health and safety benefits. In terms of public health, the primary risk management goal is to maintain if not improve the health and safety of the public. To meet this goal, a variety of public health agencies and regulatory mandates have been established to ensure that hazards are identified, assessed and characterized, and associated risks appropriately controlled. Ideally this process would be fairly straightforward and standardized. In 1983, the National Research Council provided guidance to governing agencies to improve and standardize methods for assessing risks through hazard identification, dose–response analyses, exposure assessment, and risk characterization (NAS, 1983). Since then, other reports have provided further recommendations towards the same end (NAS/IOM, 1988; NAS/NRC, 1994). However, the process for assessing as well as managing risks, even within the confined context of chemical-related hazards, has yet to be standardized among federal agencies and programs (Burke et al., 1993; PCRARM, 1997; Rhomberg, 1997). Part of the differences in approaches extend from the differences in the established regulatory goals and mandates of the various agencies (Burke et al., 1993; PCRARM, 1997; Rhomberg, 1997). While overall public health and safety are at the core of their intended goals and objectives, the interpretation of how to attain this goal varies. Table 15.1 provides an overview of some of the key Federal statutes and associated agencies established to ensure risks associated with potential toxic or hazardous chemical products are appropriately identified and managed. Detailed evaluation of the risk assessment processes used by each program (Rhomberg, 1997) demonstrate key differences in the interpretation of scientific toxicity information and associated data gaps, the estimation and assumption of exposures, and concept of acceptable risk. A primary fundamental difference in the mandates lies within the context by which cost/benefits or feasibility of controls are factored into the risk management decision making and regulatory mandated controls. This said, it has been noted that a general trend associated with chemical risk assessment and management has been towards preventing risk through control limits


TABLE 15.1 Overview of various Federal statutes and agencies charged with managing chemical-related risks Agency/ Program office

Statute/activity

Risk mandate

Risk scenarios/ focus

Special groups considered

Usual acceptable risk

US EPA Office of Prevention, Pesticides, and Toxics (OPPT) “Toxics” OPPT

Toxic Substances Control Act (TSCA)

Avoid and mitigate “unreasonable risk” via risk–benefit balancing

Reasonable worst case (occupational exposure)

Workers, consumers, general population

Federal Insecticide,

Balance risk benefits, social and economic costs; no unreasonable risk to man or environment No additives that are carcinogens; “reasonable certainty of no harm”; no cost considerations “no employee will suffer material impairment of health,” consider feasibility of standards “to protect … against unreasonable risk of injury” with “reasonably necessary” standards consider the cost/benefits

Maximum concentrations but average exposures

General population, environment

Unstated but usually below 105–106 for non occupational and 104–105 for occupational Unstated but usually 105–106 for non occupational and 104–105 for occupational

Tolerance to maximum cumulative exposures; individual (maximum) risk

General population as well as unique demographics sub-groups Workers

0 –106

Prohibit carcinogens; concentration limits

Feasibly controlled to an extent

Minimize “significant risk” through technology controls, monitoring and exposure limits

General consumers; impact of regulation (not risk) on special groups, e.g. elderly, handicapped

Unstated, unclear

“reasonably necessary” control standards; least burdensome standards that provide clear benefit “bearing reasonable relationship to costs”

“Pesticides” Food and Drug Administration (FDA)

Fungicide, and Rodenticide Act (FIFRA) Federal Food, Drug, and Cosmetics Act (FFDCA)

Occupational Safety and Health Agency (OSHA)

Occupational Safety and Health Act (OSHA act)

Consumer Product Safety Commission (CPSC)

Consumer Product Safety Act (CPSA) and Federal Hazardous Substances Act (FHSA)

283

Source: Derived from Rhomberg (1997).


Average concentrations, standard (mean) durations; population vs individual Typical use in context of cost– benefit analysis

Types of controls, actions

Specific data required for registration, use, and use limitations

RIOT CONTROL AGENTS

and prohibitions as opposed to managing risks (PCRARM, 1997). It is also rare that data representing any public health benefits of a product is documented in parallel with potential adverse outcomes. As a result, risks are evaluated and controlled from a singular scientific point of view – contrasted to a holistic risk management point of view. In addition, once obvious and serious health concerns are addressed or mitigated, residual or de minimis risks become the focus (Burke et al., 1993). For these less significant risks, it is rare that the scientific data is considered complete enough for a clear, unanimous characterization. An unfortunate outcome of the focus on data gaps and resulting uncertainties can be the lack of any clear pubic health-oriented position. This goal of balancing risks is further hindered by the lack of tools or models by which to assess and compare risks (Burke et al., 1993; PCRARM, 1997; Kammen, 1999). Frequently, “no decision” becomes the de facto decision as public health agencies balk at taking a position based on unclear data. Absent public or media attention, the impetus for Federal agencies to seek additional data or make decisions is further diminished. This situation appears to pertain to RCAs and devices. Current evaluation suggests that, with exception of OSHA workplace criteria for CN and CS (see Table 15.2), RCAs, their delivery devices, and their use have not been specifically identified under the jurisdiction of any of the listed Federal regulatory agencies or statutes, despite the fact that consumers – perhaps even more so than workers in manufacturing environments – face some of the key risks. While the scope of some statutes such as the Federal Insecticide Fungicide, Rodenticide Act (FIFRA) and Federal Food, Drug, and Cosmetics Act (FFDCA) perhaps preclude inclusion of RCA products, it is not clear whether aspects of the Toxic Substance and Control Act (TSCA), the Consumer Product Safety Act (CPSA), or the Federal Hazardous Substances Act (FHSA) have application. To the knowledge of the

TABLE 15.2 OSHA air monitoring/exposure level standards pertaining to RCAs Type of agent

CAS number

8-h time weighted average (TWA) PEL

Immediately dangerous to life and health (IDLH)

Other/notes

CN (Mace®, tear gas)

532-27-4

0.4 mg/m3 (0.05 ppm)

15 mg/m3

Recommend use of supplied air and/or self-contained breathing apparatus for different levels above PEL and above IDLH.

CS

2698-41-1

2 mg/m3

CR

257-07-8

0.3 mg/m3 (0.05 ppm) See note

See note

OC (pepper spray, capsicum)

Mixture

—

—

Sources: NIOSH, 2002; Ellison, 2000. Note PEL permissible exposure limit (OSHA).


Although not currently noted in OSHA/NIOSH, (Ellison, 2000) cites a ceiling value of 0.005 mg/m3 and an IDLH of 0.25 mg/m3; the source of these values could not be validated. No standards largely due to the inherent variation in product make up (concentration OC, type/strength of capsicum, and solvents; individual solvents may have OSHA air standards).

RISK MANAGEMENT AND PUBLIC HEALTH CONSIDERATIONS OF RCA

author, specific data needs relative to the RCAs, their formulations, or dispersion devices have not been requested or mandated by any of these ‘public health’ agencies. Another agency, the Department of Health and Human Services (DHHS), while not operating under any of these specific regulatory statutes, has a key role to identify public health risks and provide guidance towards minimizing such risks. However, to the knowledge of the author, at this time there are not any official documents produced by this organization relative to risks associated with RCAs and associated devices. Given the apparent lack of specific Federal risk assessment and risk management guidance or mandates on RCAs, the potential for mitigating or managing the risks is not being achieved and public health goals are not being optimized. However, it is noted that other federal agencies which have not traditionally been considered as having a public health role, such as the US National Institute for Justice (NIJ), have taken some steps to address some health risk issues associated with RCAs. However, these assessments are largely in the context of a particular user need (discussed further in the next section) as opposed to the toxicological identification of risk. In addition, Table 15.3 demonstrates that a few state and local agencies have also developed approaches to deal with some of the hazards associated with riot control products. This said, the approaches and information are not complete or consistent. The lack of consistent guidance is further exacerbated by heavy product marketing and advertising, which by default becomes a primary source of risk information. To provide a more complete overview of the associated risks and recommended risk management approaches, an evaluation of the needs and benefits of RCA devices is performed in order to categorize key risks and identify feasible risk management strategies.

15.3 BENEFITS DERIVED FROM THE AVAILABILITY AND USE OF RCA PRODUCTS Relative to the introduction of CN to the military in the 1950s, the use of RCAs has gone through an extraordinary evolution over the past two decades. In large part this is due to

TABLE 15.3 Existing state laws, regulations, and standards pertaining to riot control/defense spraysa State

Description of regulations/standards

California

Must have warning label, maximum canister size 2.5 oz, 70 g active ingredient; state penalties up to $1,000 (as felony) for “misuse” such as using as a joke, in anger, or possession by prohibited persons (e.g. drug addicts, minors). OC, the only allowable active ingredient in defense sprays (1997, NY State Department of Health); addresses concentration, size, packaging, and labeling (Recer et al., 2002); can only be sold by licensed firearms dealers or pharmacists. Can only be sold by state-licensed firearms dealers. OC, no stronger than 2% concentrate; CS, only accepted tear gas (no CN) and can be no larger than 35 g/can. No combination sprays. Pepper sprays only. No tear gases (CN or CS) or combination sprays. Cans can only be 15–60 g. Must have a safety feature.

New York

Massachusetts Michigan Wisconsin

Note a may not be all inclusive of all state regulations. Sources: www.peppersprayinformation.com/laws.shtml, February 2003; Recer et al. (2002).


RIOT CONTROL AGENTS

the availability of these chemicals in formulations and packages designed for individual protection as ‘defense sprays.” The “user” or “consumer” communities include two basic groups: law enforcement personnel (including military and National Guard) and individual civilian consumers. Review of available literature, statistics, as well as current day marketing advertisements demonstrate that both groups have increasing demands for these products – though each group may have slightly different product characteristic preferences as well as varying risk concerns. This section describes the key application issues relative to each of these two consumer groups.

15.3.1 Law enforcement and military needs Since the initial use of CN by the military, research and development of devices that provide law enforcement, corrections, and military personnel with an alternative to lethal force while minimizing the risk of death and injury to themselves as well as suspects, prisoners, and the general public have been ongoing. Particularly over the last two decades, the US Department of Justice, in conjunction with support from various law enforcement agencies from within the US as well as the United Kingdom (Donnolly, 2001) has demonstrated that less-than-lethal weapons research is a critical component of enhancing law enforcement capabilities as well as safety. (NIJ/BJP, 1996; Edwards, 1997; DOJ, 1999, 2001). Less-than-lethal weapons are designed to temporarily incapacitate/debilitate, confuse, delay, or restrain an adversary in a variety of situations to include riots, prison disturbances, hostage rescues, as well as apprehension of individual suspects. Law enforcement and military personnel are permitted to use the degree of force that is reasonably necessary to both protect themselves as well as accomplish their objective of deterring individuals from unwanted actions that put the larger public at risk. (DA, 1985; DOJ, 2001; Feakin, 2001). However, they are to use the lowest level of force necessary to accomplish this goal. This concept is referred to the ‘progression of force’ and can be depicted graphically as in Figure 15.1. The various types of less-than-lethal “incapacitating” devices available have their own benefits and disadvantages (Feakin, 2001; AELE, 2003) and as such each have their place in the arsenal of tools and equipment that are needed by law enforcement/military users (DA, 1985; DOJ, 2001; Feakin, 2001). Ideally, methods or weapons that have a low likelihood of causing injury, but a high potential for control, are sought. Traditional less-than-lethal means have been impact weapons such as the flashlight and nightstick/baton which have their utility, yet have been demonstrated to pose health risks (tissue damage, hematoma, or clotting) to suspects/aggressors as well as associated litigative concerns for enforcement agencies. Moreover they often provide limited means of control and protection to those attempting to maintain order and public safety (Rodericks, 1992; PCRARM, 1997; Kammen, 1999). Chemical devices have proved to be useful by such personnel in two Lower level force

Verbal persuasion

Physical escort

Devices: – Barriers – Body

Higher level force

Incapacitate

Devices: – Impact weapons (batons, flashlight) – Chemical (riot control/defense sprays) – Electrical (stun gun/tasers) – Other (water hose)

Kill

Devices: – Firearms

Figure 15.1: Progression of force and examples of mechanisms/devices used.



TABLE 15.4 Increased law enforcement authorization of less-than-lethal devices Type of device

1987 (%)

1997 (%)

% Increase

Impact weapons Chemical Stun gun/tasers

89 50a 15

93 71b 16

5 21 1

Sources: NIJ/BJP (1996), DOJ (1999). Notes a Statistical summary for 1987 identifies this category as “Mace (chemical irritants or tear gas)”. b Statistical summary for 1997 identifies this category as “pepper sprays and chemical irritants;” this may be due to the apparent preferences of law enforcement personnel for pepper sprays (OC) over the tear gas products containing CN and CR as individual control devices.

general application scenarios: crowd control and individual control. In particular, the benefits of RCAs in defense sprays for individual control and apprehension has been of significant interest to the law enforcement community over the past several years. Table 15.4 demonstrates the increased authorization of their use relative to other less-than-lethal devices based on annual statistics of US law enforcement agencies. Key factors in selection of a particular chemical device for law enforcement and military purposes vary slightly for different scenarios, but in general these include all of the following. 1 2 3 4 5 6 7 8 9 10

Effective impair/disrupt ability to fight rapid time of onset (seconds to several minutes). High safety ratio (ratio of lethal dose to effective dose, with minimal or no unintended adverse side effect). Temporary effects (non-permanent; brief duration of effects postexposure; subside without medical treatment). Predictability of effects on persons (or animals) intentionally exposed (regardless of size, physiological condition, that is, under influence of drugs or alcohol). Environmentally nonpersistent (decontamination not required and crosscontamination risk low). Manageability of incapacitated individuals (can be controlled, have some ability to walk). Logistical requirements: volume; distance; dispersal type (differs for individual applications vs crowds. Shelf life and environmental stability (operational in various temperatures). Safety (trigger controls, provisional information manuals and training). Expense.

Relative to some of these factors, aspects of product preferences are described next. As one key component, chemical/active ingredient preferences for law enforcement/ military applications were reviewed. Of the four main types of RCAs reviewed in this book (CN, CS, CR, and OC), OC has clearly been identified as the chemical of choice. Several anecdotal as well as NIJ-supported studies have supported the selection of OC over CN and CS agents from a law enforcement prospective, particularly in defense sprays (NIJ/TAP, 1994; Edwards et al., 1997; Chan et al., 2001). Though still available in some stockpiles and used by some law enforcement agencies, CN was effectively “replaced” by CS by the military in 1965 due to its increased effectiveness (immediacy of effect increased) combined with decreased risk of unintended adverse health implications. Recent assessments by the NIJ identify key reasons as to why OC provides additional benefits over CS. In particular, it


RIOT CONTROL AGENTS

is noted that unlike the CN and CS lacrimator/irritants, which work through induction of pain, OC works through induction of inflammatory effects, which result in involuntary eye closure and constriction of the respiratory tract. The NIJ explains that this difference in mechanism allows OC to be more effective at controlling assailants who are under influence of drugs or alcohol and those having limited (or possibly aggressive) response to pain. This same mechanism has been cited as the reason that OC is more effective on dogs/animals, a particular concern to many law enforcement personnel (NIJ/TAP, 1994). Perhaps of even greater significance for such personnel’s preference to the OC/pepper spray products are the decreased concerns for decontamination and cross-contamination. OC/pepper sprays are described as “biodegradable” and dissipate quickly, while cross-contamination of CN and CS (i.e. personnel contact with assailant clothing that has been sprayed with Mace/tear gas products has often resulted in irritating effects) (NIJ/TAP, 1994). A conclusion of one particular NIJ study on the use of OC notes “in arrest and other confrontational encounters, [use of OC] effectively neutralized aggressive suspects and animals. Study findings also suggest that the use of OC reduced the incidence of assaults on police officers, injuries to both officers and suspects, and use-of-force or brutality complaints registered” (Edwards et al., 1997). This, supported with additional statistics and anecdotal reports of law-enforcement officers, demonstrates that OC is the current RCA of choice for defense sprays (Edwards et al., 1997; Chan et al., 2001.) However, data relative to preferred use of such chemicals for crowd control purposes was less clear. In addition it is noted that CR has not been assessed for use outside the military. Despite apparent favor of OC products, the NIJ is silent on the specific identification of preferred percentages of OC or concentration of capsicum. Reports from the NIJ explain that though OC in pepper sprays is available as 1–10% of spray volume, the greater significance relative to potency is the specific type or ‘grind’ of the capsicum used, which is traditionally represented by the term Scoville Heat Unit (SHU). As such, a 10% OC spray of 1 million SHU is less potent than a 10% OC spray of 2 million SHU (NIJ/TAP, 1994; Edwards et al., 1997). But what is not clear from the statistics or studies showing increased effective use in OC products is whether a specific percentage or SHU is more effective or desired (or which ones were used). The applications scenarios (crowd control vs individual control) require devices with different disseminating mechanisms. For crowd control, pyrotechnic/thermal discharge/large canister fogging systems remain of interest. Increased focus on individual defense spray systems has resulted in numerous variants on spray systems (such as those that produce line streams versus those that spray aerosol out in broader dispersal cone), different trigger mechanisms and safety devices, and different volumes/durations of spray (such as 5 s vs 30 s continuous sprays). Specific preferences for release/spray mechanisms was not identified, though NIJ reports noted that for specific applications, different mechanisms might be preferred (NIJ/TAP, 1994; Edwards et al., 1997). What the NIJ has noted – particularly relevant to use of OC – is the implications of the carrier/solvent. A particular concern associated with isopropyl alcohol as a carrier was based on an incident involving the use of a taser after spraying an assailant with pepper spray that effectively lit the assailant on fire. Other than this concern, benefits over nonalcohol-based carriers included a perceived increased (quicker, more effective) absorption of OC with alcohol, better atomizing effects in colder weather, and less toxic side effects (NIJ/TAP, 1994).

15.3.2 Individual consumers for personal protection Civilian use of defense sprays may be a somewhat smaller market than for official law enforcement applications, but this user community has grown substantially over the past



several years. These defense sprays provide a less extreme and more readily available – and less regulated – alternative to firearms as a means of personal protection. In so far as both law enforcement and individuals use individual defense sprays, many of the defense sprays are marketed towards both sectors. However, the selection criteria of key concern to this user group may be less inclined to be concerned about the safety ratio, environmental persistence, or temporary nature of effects. In fact, some advertisements point out to this consumer that their application needs (as a means to detain aggressor and afford escape time) require longer effect durations than those desired by law enforcement personnel. This group of consumers is less likely to be concerned with unintended severity of health effects to those individuals they use their product against. But in addition, with the exception of safety precautions advertised, this consumer group may also be less aware of the potential risks towards themselves or unintended victims. Statistics compiled by Recer et al. (2002), from poison control center data from 1991–95 demonstrates that accidental exposures to these defense sprays are not uncommon, and particularly seem to occur with children. Without any regulatory involvement, this group must rely solely on information provided by commercial manufacturers when making decisions relative to product selection, use, and risk mitigation.

15.4 CATEGORIZING KNOWN AND POTENTIAL HAZARDS ATTRIBUTED TO RCAs The hazards associated with RCAs depend on the type of agent, the dose, the mechanism of delivery/exposure (including associated solvents, propellants, or other additives) and the susceptibilities of the persons exposed. The populations at risk are increasing due to the expanding use and resulting increasing number of exposure scenarios, both intentional and accidental. As described in various chapters of this book, key health implications are associated with both active ingredients as well as the carriers/solvent and propellants used in selfdefense formulations. Additional concerns have been identified with the potential health implications associated with thermal and combustion or breakdown products associated with pyrotechnic RCA devices used for military and crowd control purposes. While one example – the cyanogenic (cyanide-related risk) potential of CS was described as minimal (Chapter 6), a comparative assessment of lethality of these agents from aerosol sprays versus pyrotechnically generated sources suggests that increased hazards are associated with thermal source generation. However, a full characterization of the health risks associated with the resulting products and mixtures has yet to be fully identified. As a primary product of public interest, defense sprays are perhaps a greater public health concern, however. Table 15.5 summarizes some of the health concerns identified with the agents and some of the associated solvent carriers. Included is a lethality estimate of the agents along with estimate of the minimum concentration needed to produce the intended effects, the ratio of which describes the “safety ratio” identified as item (2) in the list of key selection criteria of RCAs given before. The exposures may occur during production (incidental occupational exposures) or training (required “use” scenarios or related accidents), during real world “use” (both of targeted individuals or accidentally from clothing cross-contamination or wind shift changes), or in accidents when discharge is unintended or misdirected. The majority of exposure incidents are expected to be brief in duration and involve concentrations that would not be expected to cause more harm than the intended temporary physiological effects on eyes and respiratory tract. However, there is potential for non-intended, more serious, long-lasting, effects if exposures involve higher than typical concentration designs,


290

TABLE 15.5 Summary of key health risks considerations associated with modern day RCAs Type of agent

Lethality dose estimatea (mg-min/m3)

Minimal effective dosea (mg/m3)

Safety ratiob (lethality/ effective dose)

Specific health effects of concerna,c

Other notes/concerns

CN (tear gas, Mace®)

~8,000

0.3

~27,000b

Cross-contamination risk – rough surfaces including clothing for extended periods requires extended hour aeration and washing – do not rub. Avoid use in enclosed spaces.

CS (tear gas)

~60,000

~0.1–1

~60,000b

Eye injury (potential permanent vision impairment); Skin erythema/vesiculation (blister), sensitization; respiratory tract injury/pulmonary edema; reactive airways dysfunction syndrome (RADS); potential fatality. Similar to CN but of lesser severity; (skin) effects more localized to area of direct exposure.

CR

100,000

1

100,000b

Inhalation effects negligible (unlike that of CN or CS); Eye irritation less than that of CN/CS; skin effects more pronounced than CS; teratogen (Lewis, 2001)

OC (pepper spray)

—

Varies

Presumed to be much 60,000b

Some potential for ocular/skin/airway injury; Considered relatively “safe” as less likely to cause severe effects than CN or CS. However one case of death in asthmatic noted.

Varies (based on %, SHU, carrier solvents)d

Cross-contamination risk – rough surfaces including clothing for extended periods requires extended hour aeration and washing – do not rub. Avoid use in enclosed spaces. Relatively new so not much data available on actual use; not currently legal for commercial use (only military). Avoid use in enclosed spaces. More persistent in environment/clothing than CS. Relative health risks/efficacy associated with different OC percentage and/or concentrations of capsicum not clear. Avoid use in enclosed spaces. Use cold water vs warm/hot to decontaminate; avoid oily soaps and or lotions, do not rub.

Notes a Derived from various sources (DA, 1996; Sidell, 1997; Smith, 1999; Olajos and Salem, 2001; Hess, 2002). b Ideally, the higher the Safety Ratio (SR), the better. However, it is noted that the degree of confidence for each toxicity estimate varies from chemical-to-chemical, and therefore the SR may be somewhat misleading. c Health effects based on typical use scenarios; anecdotal evidence (see Sidell, 1997) indicates potential health risks associated with ingestion hazards but these are not addressed here. d Synthetic capsaicin (nonivamide) potentially “safer” than OC but little data for comparison.



are repeated, or last for extended durations. As described elsewhere in this book, there are those who are more “susceptible” to effects of concern, such as those who suffer from preexisting respiratory or heart problems, children, or those who are immunocompromised. Table 15.6 summarizes the types of groups and circumstances associated with various exposures to RCAs that are anticipated within the US within a given year. The specific types of hazards/health risks relative to these groups are summarized as well. As the actual numbers of individuals exposed, or even numbers of persons with documented adverse health outcomes or requiring medical treatment, are not available, the size of each category is described semi-quantitatively by means of subjective assumptions.

15.5 TYPICAL APPROACHES TO MANAGING CHEMICAL RISKS 15.5.1 Quantified exposure limits and monitoring controls As described in Chapter 13, established risk assessment methodologies can be used to portray health risks associated with a chemical through means of quantified exposure limits. This information can be used to portray the relative toxicity of one chemical to another but is most commonly used as a finite basis for monitoring exposures, limiting use and/or exposure, legal action, etc. However, the disadvantages of this process stem from the degree of completeness and accuracy of available toxicity data as well as its relevance to actual human exposures (Rodericks, 1992; Burke et al., 1993; Kammen et al., 1999). As noted in Table 15.2, existing OSHA work place standards have been developed for CS and CN, but problems inherent to the various mixtures associated with OC products have prevented such criteria being established. However, designation of exposure/monitoring criteria for these chemicals may have limited applications given the wide use in civilian populations. The establishment of even short-term exposure criteria for general population scenarios such as Emergency Exposure Guidelines Levels (ERPGs) (AIHA, 2002) or Acute Exposure Guidelines Levels (AEGLs) (NAS/NRC, 2001) may provide some more specific quantitative criteria by which to compare these agents but one can see the relative complexities of developing appropriate values for comparison. Inconsistencies among product brands, mixtures, and purity and other uncertainties can weigh heavily on resulting toxicity estimates. Furthermore, laboratory results may not always represent the real world exposure scenarios. As demonstrated in Table 15.6, the exposure scenarios involving RCAs are variable and typically nonroutine, with limited environmental controls. Monitoring and quantification of exposures therefore may be a limited approach to control unintended exposures.

15.5.2 Precautionary approach The precautionary approach to risk management incorporates some aspects of hazard identification and exposure assessment – but does not require specific, quantified risk levels or thresholds – or estimation of data uncertainty (Montague, 1998; Foster et al., 2000). In the extreme application of this approach, a chemical can be prohibited from production if certain adverse impacts are identified, even if such impacts are not specifically quantified or supported by data. While this approach can prevent adverse implications that otherwise might require additional time and resources to gather, it can also potentially prevent all or some uses of a chemical that could minimize other public


TABLE 15.6 292

Populations at risk to RCA exposure Type of exposure (intentional vs accidental) and type of population/setting Occupational Intentional use exposures

Accidental exposuresc

Description of scenario

Health concerns

Annual US exposuresa

Industry Police Military

None. Live training requirement. Live training requirement.

NA Low to moderate

Industry

During production processes.

Police Military

During live training or active duty; Example – if wind direction turns release onto unsuspecting trainees. Example – may be crosscontaminated by clothing of subject(s) brought under control. May be cross-contaminated by clothing of subject(s) brought under control.

NA Acute effects; concerns for susceptible individuals;b increased sensitivity; long term effects – uncertain. Increased sensitivity; long term effects – uncertain. Acute effects; concerns for susceptible individuals;b increased sensitivity; long term effects – uncertain.

Acute effects; concerns for susceptible individuals.b

Low

Acute effects; concerns for susceptible individuals and aggravated individuals;b increased sensitivity; long term effects – uncertain. Acute effects; concerns for susceptible individuals.b

Low to moderate

Hospital staff Public Intentional use exposures

Accidental exposuresc

Public crowd – protestors Individual Individual Public crowd

By personnel charged with crowd control responsibilities. By personnel deterring or arresting aggressive or violent individuals. Individual owners unintentional use of personal protective sprays. Wind shift changes could expose unsuspecting and innocent bystanders.

Low Low

Moderate to low

Notes a Population exposure estimate categories are not based on hard data but are author’s assumptions as described by following scale: High 1,000,000; Moderate 1,000,000 1,000; and Low 1,000. These estimates are assumed to overestimate actual number of persons exposed. Number of exposed should not be confused with number of those who incur actual adverse health affects, which is also unknown but would be less than number exposed. b Susceptible individuals include those with existing respiratory diseases or heart conditions; aggravated individuals refer to those who are mentally ill, intoxicated, and/or under the influence of drugs which can incur increased violent behavior and/or health side effects. c Accidental exposure estimates are in part noted by Recer et al. (2002) who through extrapolation from Poison Control Center reports of injuries in conjunction with information from manufacturers’ estimated exposures over five year period to defense sprays (CN, CS, and OC) as approximately 500,000, or average 100,000 per year. © 2004 by CRC Press LLC


health concerns (such as a specified drug, pesticide or food preservative). Under a less extreme use of this approach, specific applications may be limited or only very unique applications may be defined/authorized in order to minimize exposures/impacts that are of particular concern. Due to the relatively diverse circumstances associated with RCAs, a use of the precautionary approach to policy and guidance would be logical choice. Given the lack of any standard source of information and guidance, many precautionarybased courses of action (awareness and information resources, training, standardization) can be taken to better control the development and use of RCAs to ensure that their use is ultimately in the best interest of the public. While the lack of specific quantified exposure guidelines may limit agencies or health professionals’ abilities to estimate dosage and assess scenarios, policies and guidance do not have to rely on such criteria, especially when exposures are unlikely to be sampled and quantified.

15.5.3 Management through risk communication A common relatively low cost form of managing health risks, especially for risks that are associated with a “benefit” or personal choice, is through the provision of accessible, understandable, and unbiased information to those at risk or responsible for making decisions governing the risk. Risk communication can be performed without excessive strict regulatory mandates, but typically does require some production/manufacturers action/input to the process, which is often achieved through some regulatory drivers. For managing and minimizing the unintended impacts associated with RCAs, basic information regarding specific agents authorized for use in a given area, the types of effects, and warnings for potential unintended outcomes, and procedures to address medical emergencies and decontamination would be useful information for law enforcement agencies and hospitals (emergency rooms) as well as to the general public. However, such information must be accurate and reliable – and based on at least some scientific fact (acknowledging gaps in science). Our current state of the science has allowed manufacturers to portray products that have varying levels of effectiveness and varying levels of potential adverse side effects – the exact extent of a products’ effectiveness or severity of effect is not likely to be truly known. Advertisements simultaneously decry their “extremely potent” products, while claiming them to be safe. As demonstrated through out this book, the variability in products (the agents, concentrations, dispersal mechanisms, and associated solvents or additives) have not allowed a full characterization of products. Manufacturers instead are establishing “new” products by even mixing the various agents (such as CS and OC) – further adding to the uncertainty of the efficacy and particularly the overall safety of these products. Some states (Table 15.3) have attempted to put some control on these products and required some hazard labeling, but the generic nature of such information may not be adequate. The confusion resulting from lack of a centralized, unbiased, thorough, factual information source for RCAs relative to the effects/incidents of public health concern, are exemplified through numerous calls to the National Poison Control Center (data from 1991 to 1995, Recer et al., 2002) and responses from hospitals that are overwhelmed with victims of RCAs where queries on appropriate decontamination and treatment (Weir, 2001).

15.6 STRATEGIES FOR MANAGING RCA RISKS The following paragraphs describe five key areas of risk management that can be enhanced relative to the production and use of RCAs and associated products. Table 15.7 details aspects of these strategies relative to unique populations at risk.


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TABLE 15.7 Actions to minimize non-intended adverse outcomes Exposed group

Scenarios

Actions to minimize non-intended adverse outcomes

All

Any/all

Industry

During production processes

Police

Live training requirement Accidents

Establish standard/appropriate product test protocol. Establish product standards – agent type, maximum concentrations, volumes, types of carriers/solvents, use limitations, efficacy standards. Establish tracking mechanisms for reporting use and exposure incidents to enhance epidemiology assessments. Training/awareness. Medical baseline and surveillance. Engineering control (e.g. hoods). Minimize enclosed spaces. Use of PPE. Air monitoring. Training requirements (for organization and individuals). Medical baseline and surveillance (no live training for susceptible individuals; reduce repetition of live training). Use of PPE. Prevent use in enclosed spaces; scenarios with unpredictable wind patterns. Use of surrogates for training. Training/awareness (treatment, decontaminations). Advanced alert to agent use/type by law enforcement in large crowd scenarios. Use of PPE. Training for personnel on other nonlethal options and limitation/benefits of use for RCAs. Provide specific use policies and guidelines for specified agents and dispersal mechanisms. Ensure adequate public knowledge and identify agent and susceptible individuals’ prior use.

Military

Medical

Cross contamination Patient care

Public crowd

By personnel charged with crowd control responsibilities

Individual

By personnel deterring or arresting aggressive or violent individuals Individual owners unintentional use of personal protective sprays

Individual

Training requirements for use. Packaging and labeling (warning). Mandate safety trigger/features.

15.6.1 Identification and selection of riot control compounds for use As indicated, proper risk management is a trade-off of benefits against adverse implications. Clearly, not every selection criterion can be maximized, and for some scenarios a particular agent might be better suited than another. But overall, science has advanced the military as well as civilian law enforcement communities toward better agents of choice. However, as RCAs have become increasingly popular in civilian applications (law enforcement and personal defense sprays), the potential for exposure has gone up, and the degree of certainty with which the science supports their safety is weakened by increasing products mixtures. While NIJ (NIJ/TAP, 1994; Edwards et al., 1997; Chan et al., 2001,) supported an assessment augmented by anecdotal information that clearly identifies OC products as



preferential to CN or CS products, parallel “studies” as to the associated risks are not as clear. That said, most accounts describe OC as relatively “safe” especially in comparison to CN and CS. Specific risk assessment steps were used by the military to select CS over CN, but available documentation of the risk assessment procedures used to compare (or preferentially select) these agents with CR or OC products are limited. While no federal public health agencies have addressed the issue, some states (Table 15.3) have made specific preferential criteria of active ingredient a part of their regulation. Recer et al. (2002) demonstrates the basis for a decision in New York to effectively select OC sprays over CS or CN. That said – the evaluation does not fully examine the consideration of the percentage or concentration of capsicum in these products, nor does it address or prohibit any specific carrier/solvent products. Ideally, to optimize the management of risks and associated public health goals, specific criteria for RCA and product data (efficacy, toxicity) – in light of its intended use, with specifics on agent type, concentration, and associated solvents and additives should be readily available for every product and such information should be utilized by appropriate agencies to identify acceptable vs nonacceptable products or use scenarios. Unfortunately, unless a federal organization (possibly under the jurisdiction of one of the statutes described in Table 15.2) mandates that such information be established (with consistent protocols), this process will be hindered.

15.6.2 Establishing user requirements, labeling, training For official agency use, standard training should be provided. This should include coverage of potential non-predicted or non-intended effects as opposed to common manufacturers generalities that claim that the agent stops everyone and/or that the agent only causes temporary effects and is therefore completely safe. While compliance and control training is an absolute necessity, injuries or death may still occur because of the human factors of misapplication, miscalculation, and excessive strength, or unique susceptibilities. Official users should be warned to be prepared for potentially more serious health implications and under what conditions medical attention is advised. As various products have different level of persistency and cause for cross-contamination, appropriate information as to the type of decontamination methods should be provided. For private citizens use training may be less feasible, but appropriate information should be included with the product.

15.6.3 Education and awareness to those intentionally or incidentally exposed Though the “shock” value of the effect caused by an RCA may be enhanced by the lack of knowledge one has regarding its temporary nature, some basic risk communication and “warning” information to the public at risk of exposure (such as at a protest rally) is an appropriate means to alert those who may be of potential increased susceptibility and minimize follow on perceptions. This could facilitate improved medical response and avoid incidents such as that described by Weir (2001) where hospital staff were overwhelmed with victims of tear gas after a crowd demonstration and had little information as to how best to triage and treat. Information on specific agents/products, their effects, and specific decontamination procedures should also be provided to emergency medical personnel and hospital staff to avoid cross-contamination and facilitate any medical treatment.


RIOT CONTROL AGENTS

15.6.4 Occupational controls and medical surveillance Accidental occupational exposures can be managed through training, procedures, and appropriate personal protective equipment/clothing. But various agencies including the military include “intentional exposure” in their training routines to build confidence in the product while also demonstrating techniques to handle “accidental” exposures during real-word events. Some have described this type of training as inhumane and unnecessary, while others have described it as invaluable. While there is logic to both sides, the context of repeated training of this nature demonstrates possibility of repeated exposures and the resulting impacts on health. Standard guidance on this issue, or general rules of thumb: type of product, condition of exposure (distance, time, physical state), frequency of training, conditions for exemptions, and documentation of medical evaluations, questionnaires and identified medical outcomes would further medical and scientific assessment and could prevent inappropriate or dangerous “intentional” exposures.

15.6.5 Establishment of use/exposure/incident reporting database One of the problems with ascertaining the risks associated with riot control products is the limited epidemiological data that has been compiled. Actual product sales are not tracked, but more importantly incidents of use – particularly those with adverse outcome are not documented in a standardized database. Ideally this would be established at a national level. This said, state and local public health agencies have authority to potentially address this need. Information from private citizens could be gathered from local hospitals, while law enforcement personnel could self-report. To maximize its use, acquisition of the data would need to be as detailed as possible; to include specific product names, active ingredients, description of exposure duration and scenario, and victim information (age, gender, physical condition/extenuating disease or circumstances). Once available, more in-depth analyses can support improved risk assessment of products and help determine if additional risk management strategies are needed.

15.7 CONCLUSIONS Modern day RCAs have an extremely important role not only in military peacekeeping and law enforcement, crowd/individual control applications, but also as an increasingly popular form of personal protection. It is likely that use – and thus related exposures – to these agents will continue to grow. Because they are intended to cause discomfort or pain, one might presume that public health agencies play a role in the production and use of such chemicals. However, limited information, much less policy, or guidance is provided by Federal health agencies and only a few states have taken steps to control the use of such products. By and large, use of these products does not pose a substantial public health problem to our society. Science has helped reduce some of the risks and improved utility through identification of products that appear to provide a better safety ratio of effectiveness over lethality or severe incapacitation. But there are several potential health risks to those using the products, those who are intended victims, and others who are incidentally or accidentally exposed. In addition, because of the variety of agents and formulations, not all is known about the potential for certain adverse health implications associated with the products used today. It is clear that risk is inherent with the use of chemicals that



are intended to cause harm. Unfortunately current risk management strategies are not being optimized to minimize the risk associated with RCA products. Some of the strategies identified include (1) product specific information and selection recommendation, (2) basic user training/labeling requirements, (3) technically accurate, unbiased, publicly accessible information, (4) occupational controls and medical screening, and (5) a standard central use/exposure incident database. Some of these strategies are more resource intensive than others, and ideally they would all be more effectively addressed at a national (Federal) level. But some state and local entities have taken some of these actions and provided example for other agencies to consider.

REFERENCES AMERICANS FOR EFFECTIVE LAW ENFORCEMENT (AELE) (web-2003) Use-of-Force Tactics and Non-Lethal Weaponry, A Periodic Training Guide Provide Complimentary to Prosecution and Law Enforcement Agencies, Park Ridge, IL: AELE. http://www.aele.org/alert.html AMERICAN INDUSTRIAL HYGIENIST ASSOCIATION (AIHA) (2002) Emergency Response Planning Guidelines and Worker Environmental Exposure Levels Handbook, Fairfax, VA: AIHA Press. AFTERGOOD, S. (1994) The “Soft Kill” Fallacy, The Bulletin of the Atomic Scientists, http:// www.thebulletin.org/issues/1994/so1994/so1994Aftergood.html BURKE, T.A., TRAN, N.L., ROEMER, J.S., and HENRY, C.J. (1993) Regulating Risk: The Science and Politics of Risk, Washington, DC: ILSI Press. CHAN, T., VILKE, G., CLAUSEN, J., CLARK, R., SCHMIDT, P., SNOWDEN, T., and NEWMAN, T. (December 2001) Pepper Spray’s Effects on a Suspect’s Ability to Breathe, National Institute of Justice, US Department of Justice, http://www.ojp.usdoj.gov/nij/pubs-sum/188069.htm DEFENSE THREAT REDUCTION AGENCY (DTRA) (2001) Weapons of Mass Destruction Terms Reference Book; DTRA-AR-40H; Alexandria, VA: DTRA. DONNOLLY, T. (2001) Less Than Lethal Technologies Initial Prioritization and Evaluation, Publication No 12/01; Police Scientific Development Branch, Home office Policing and Crime Reduction, UK, http://www.homeoffice.gov.uk/pcrg/psdb/publications/lesslethal.pdf EDWARDS, S., GRANFIELD, J., and ONNEN, J. (February 1997) Evaluation of Pepper Spray, National Institute of Justice, Office of Justice Programs, US Department of Justice, http://www.ojp.usdoj.gov/nij/pubs-sum/162358.htm ELLISON, D.H. (1999) Handbook of Chemical and Biological Warfare Agents, Washington, DC: CRC Press. FEAKIN, T. (2001) Bradford Non-Lethal Weapons Project, Research Report 3; Center for Conflict Resolution, http://www.brad.ac.uk/acad/nlw/research_report_number_three.html FOSTER, K.R., VECCHIA, P., and REPACHOLI, M.H. (2000) Science and the Precautionary Principle, Science (May), 979–981. HESS, D.W. (2002) Long-term effects of pepper spray, Pennsylvania – Susquehanna Health System website: http://www.shscares.org/services/lrc/cme/pepperspray.asp KAMMEN, D.M. and HASSEENZAHL, D.M. (1999) Should we Risk It? Exploring Environmental, Health, and Technological Problem Solving, Princeton: Princeton University Press. LEWIS, R. (ed) (2001) Sax’s Dangerous Properties of Industrial Chemicals, John Wiley and Sons. MONTAGUE, P. (February 1998) The Precautionary Principle, Rachel’s Environment and Health Weekly, #586. NATIONAL ACADEMY OF SCIENCES (NAS) (1983) Risk Assessment in the Federal Government: Managing the Process, Washington, DC: National Academy Press. NATIONAL ACADEMY OF SCIENCE – INSTITUTE OF MEDICINE (NAS/IOM) (1988) The Future of Public Health, Washington, DC: National Academy Press. NATIONAL ACADEMY OF SCIENCES/NATIONAL RESEARCH COUNCIL (NAS/NRC) (1994) Science and Judgment in Risk Assessment. Washington, DC: National Academy Press.


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NATIONAL ACADEMY OF SCIENCES/NATIONAL RESEARCH COUNCIL (NAS/NRC) (2001) Standards Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals. Washington, DC: National Academy Press. NATIONAL INSTITUTE OF JUSTICE – BUREAU OF JUSTICE PROGRAMS (NIJ/BJP) (1996) National Data Collection on Police Use of Force, NCJ-160113. NATIONAL INSTITUTE OF JUSTICE – TECHNOLOGY ASSESSMENT PROGRAM (NIJ/TAP) (March 1994) ‘Oleoresin Capsicum: Pepper Spray as a Force Alternative’, US Department of Justice, http://www.justnet.org/pdffiles/pepper.pdf NATIONAL INSTITUTE OF OCCUPATIONAL SAFETY AND HEALTH (NIOSH) (2002) NIOSH Pocket Guide of Hazardous Substances. http://www.cdc.gov/niosh/npg/npg.html OLAJOS, E. J. and SALEM, H. (2001) Riot control agents: pharmacology, toxicology, biochemistry and chemistry, Journal of Applied Toxicology, 21(5): 355–391. PEPPER SPRAY STORE (2003) Pepper Spray Information: Pepper Spray, Tear Gas, Mace, and the Law; http://www.peppersprayinformation.com/laws.shtml PRESIDENTIAL COMMISSION ON RISK ASSESSMENT AND RISK MANAGEMENT (PCRARM) (1997) Framework for Environmental Risk Management; Final Report, Volumes 1 and II. http://www.riskworld.com/ Nreports/1997/risk-rpt/pdf/EPAJAN.PDF RECER, G.M., JOHNSON, T.B., and GLEASON, A.K. (2002) An evaluation of the potential public health concern for the defense spray active ingredients oleoresin capsicum, o-chlorobenzylidene malononitrile, and 2-chloroacetophenone, Regulatory Toxicology and Pharmocology, 36: 1–11. RODERICKS, J.V. (1992) Calculated Risks: The Toxicity of Human and Health Risks of Chemicals in our Environment, United Kingdom: Cambridge University Press. RHOMBERG, L.R. (1997) A Survey of Methods for Chemical Health Risk Assessment Among Federal Regulatory Agencies. Report prepared for the National Commission on Risk Assessment and Risk Management. SIDELL, F.R. (1997) ‘Riot Control Agents,’ (Chapter 12) Textbook of Military Medicine, Part 1: Medical Aspects of Chemical and Biological Warfare. WRAMC, Washington, DC: TMM Publishing. SMITH, C.G. and STOPFORD, W. (1999) Health hazards of pepper spray, North Carolina Medical Journal, 60: 150–159. US DEPARTMENT OF THE ARMY (DA) (1985) Field Manual (FM) 19–15: Civil Disturbances. Washington, DC. US DEPARTMENT OF THE ARMY (DA) (1996) ‘Riot Control Agents’ (Chapter 7), Field Manual (FM) 8–9: NATO Handbook on the Medical Aspects of NBC Defensive Operations, Washington, DC. US DEPARTMENT OF JUSTICE (DOJ)-Office of Justice Systems (1999) Statistics Law Enforcement and Administration Statistics for 1997: data for individual state and local agencies with 100 or more officers. US DEPARTMENT OF JUSTICE (DOJ) ( January 2001) Principles of Promoting Police Integrity, http://www.ojp.usdoj.gov/lawenforcement/policeintegrity/welcome.html WEIR, ERICA (2001) The health impact of crowd control agents, Canadien Medical Association Journal, 164(13): 1889–1890.

DISCLAIMER NOTICE The views expressed in this chapter are those of the author and do not necessarily reflect the views or policies of US Army Center for Health Promotion and Preventive Medicine. Mention of trade names or commercial products does not constitute endorsement or recommendation of use.


CHAPTER

Environmental Issues Involving Riot Control Agents

16

LARRY E. ERICKSON, ATHERTINA N. STEINAU, TERRIE BOGUSKI, AND FREDERICK W. OEHME Kansas State University, Manhattan, KS 66506

16.1 INTRODUCTION In the last 30 years, environmental issues have received more attention, and many studies of environmental effects have been reported. In this chapter the environmental literature on the fate of riot control agents (RCAs) in the environment is reviewed. The degradation pathways often lead to intermediate compounds which are of toxicological and environmental interest. Thus, the literature on some important intermediate compounds is reviewed as well. Microbial degradation processes appear to play a significant role for each of the RCAs that are considered. This review considers ecotoxicological risk and environmental degradation of o-chlorobenzylidene malononitrile (CS), 2-chloroacetophenone (CN), dibenz[b,f]1:4-oxazepine (CR), and oleoresin capsicum (OC). All of the compounds are biodegraded when environmental conditions are appropriate. When these compounds are present as solid particles in dry soil, they are fairly stable because of their low solubility in water and their low vapor pressure. The environmental and toxicological issues associated with the use of RCAs in enclosed spaces is included in this review. Adsorption to organic compounds in building materials and furniture affects the duration of RCAs in buildings.

16.2

O-CHLOROBENZYLIDENE MALONONITRILE

CS, which is o-chlorobenzylidene malononitrile, is a solid at room temperature. Because CS undergoes hydrolysis to o-chlorobenzaldehyde and malononitrile in aqueous solutions (Patai and Rappoport, 1962), there is limited data on its solubility in water (Katz, Chapter 3 of this work; Keller et al., 1986). Estimation methods of Yalkowsky et al. (1983) based on a melting point of 93C, and an estimated log Kow of 2.76, give aqueous solubilities in the range of 116 to 221 mg/L. The Material Safety Data Sheet, US Army Edgewood Research, Development, and Engineering Center reports a solubility of 0.02% or 200 mg/L. In dry unsaturated soil, the solid particles may be relatively stable until they are dissolved in water. Keller et al. (1986) reported that the degradation rate of CS increased with soil moisture. Olajos (Chapter 4 of this work) has reviewed the biochemistry of CS degradation and reported that the o-chlorobenzaldehyde can be oxidized to o-chlorobenzoate, or reduced to o-chlorobenzyl alcohol. The environmental fate of chlorinated aromatic compounds has


RIOT CONTROL AGENTS

been investigated and reviewed by Fetzner and Lingens (1994) and Fetzner (1998). Under aerobic conditions the o-chlorobenzaldehyde is oxidized to o-chlorobenzoate, which is converted to catechol (Engesser and Schulte, 1989; Fetzner et al., 1989; Romanov and Hausinger, 1994). Under anaerobic conditions o-chlorobenzoate is converted to benzoate by ortho reductive dehalogenation (Sharak Genther, 1999). Photo heterotrophic bacteria (Van der Woude et al., 1994) and photosynthetic microalgae (Noma et al., 1992; Hook et al., 1999) have been reported to biotransform halogenated benzaldehydes and benzoates. Van der Woude found that a pure culture of Rhodopsendomonas palustris could dechlorinate 2-chlorobenzoate when growing photo heterotrophically on 3-chlorobenzoate. Hook et al. (1999) and Noma et al. (1992) found that o-chlorobenzaldehyde was reduced to o-chlorobenzyl alcohol by several algal species. Sharak-Genther (1999) reported that 2-chlorobenzaldehyde was reduced to 2-chlorobenzyl alcohol by anaerobic cultures which transformed 2-chlorobenzoate to benzoate. The malononitrile has a relatively short half life in soil and water. Under aerobic conditions nitriles can be converted to organic acids (Alexander, 1999).

16.2.1 Environmental fate in soil The environmental persistence of CS in soil had been investigated because of its usage in field exercises (Keller et al., 1986). Studies performed at Eglin Air Force Base to determine environmental toxicity of CS involved an evaluation of CS degradation rate in soil and the effect of other variables, such as moisture, light, and multiple CS applications. This study reported CS is readily degradable having a “conservative” half-life of 3.9 days in the test soil under specified conditions. Additionally, the degradation of CS is highly dependant on environmental factors. Moisture in the form of “mist” or rainfall increased CS degradation rate when compared to the corresponding controls. The relative humidity in the environmental chamber was set at 45% for the duration of the investigation. The investigators found that the degradation rate was greater for soil placed in “zip loc” bags. This may be because more moisture is retained in these samples compared to the open samples. Moreover, these studies confirmed that CS degradative patterns/rates are enhanced with light, and it is believed that since the light intensity used in this study was much less compared to normal field conditions, the break-down of CS can be more rapid in its “normal” field application settings. Other environmental factors, such as temperature and the “run off” of CS to subsurface soil via rain, may also affect CS degradation. Soil incorporated with CS had varying effects on the emergence of different seedling species when applied within four weeks prior to planting (Morrison et al., 1974); however test plants at the “incapacitating” exposures for field applications (10–20 mg/m3) did not result in substantial plant damage (Morrison et al., 1974; Keller et al., 1986). Additional studies have determined that acute toxicity of CS to some aquatic plants such as duckweed is due to malononitrile (Worthley and Schott, 1971; Schott and Worthley, 1973). It is furthermore highly toxic to both woody and herbaceous terrestrial plants, affecting mainly leaves and reduction in shoot growth at a previously tested dose of 60–120 gm/m3 (Morrison et al., 1974).

16.2.2 Aquatic toxicity CS, being only partially water soluble, undergoes a slow hydrolysis process that forms two breakdown products, o-chlorobenzaldehyde and malononitrile. Of the two compounds, malononitrile has the least stability and toxic characteristics with an oral LD50 of more than 100 mg/kg in rodents (Punte et al., 1963). While the o-chlorobenzaldehyde may be oxidized to o-chlorobenzoate or reduced to o-chlorobenzyl alcohol, these chlorinated compounds,


ENVIRONMENTAL ISSUES INVOLVING RCA

as a group, are more stable than the malononitrile. Paradowski (1979) reports that o-chlorobenzaldehyde has an LD50 of 8.5 mg/kg (0.06 mmoles/kg) and a half life of 0.69 min in rabbits. Paradowski (1979) shows that the concentration of o-chlorobenzaldehyde in the blood following an LD50 dose of CS approaches the LD50 value for o-chlorobenzaldehyde. He reaches the conclusion that the hydrolysis product o-chlorobenzaldehyde may be responsible for the lethal effects when CS was administered to the blood of rabbits. The oxidation product, o-chlorobenzoate, or o-chlorobenzoic acid, has an LD50 of 6 g/kg in rodents (Punte et al., 1963). It is less toxic than o-chlorobenzaldehyde. Abram and Wilson (1979) investigated the aquatic toxicity of CS, o-chlorobenzaldehyde, and malononitrile using rainbow trout. They present graphs of median period of survival vs concentration for CS, o-chlorobenzaldehyde, malononitrile, and equimolar mixtures of the two hydrolysis products. In their graphs, the effects of CS, o-chlorobenzaldehyde, and the equimolar mixture are fairly similar, while malononitrile is less toxic when the concentrations are converted to molar units. For example, for a median period of survival of 1,000 min the corresponding concentrations in mmoles/L are 0.031 for CS, 0.032 for o-chlorobenzaldehyde, 0.17 for malononitrile, and 0.016 for the equimolar mixture. Malononitrile is reported to be somewhat less toxic than CS and o-chlorobenzaldehyde (Abram and Wilson 1979). Abram and Wilson also report values of LC50; however, their tabular values for CS and the equimolar mixture do not appear to be consistent with the graphs which are presented. CS and its breakdown products were also studied on the mumichog, Fundulus heteroclitus (Linnaeus), an aquatic species indigenous to Carroll Island (Pearson, 1975). Varying exposures of 1.0, 10.0, and 35.0 mg/L of o-chlorobenzaldehyde showed no abnormal behavior or gross morphological effects when compared to controls. However, when exposed to CS at 6.3, 7.5, 8.5, and 10.0 mg/L, symptoms profoundly differed with frequent body convulsions and “coughing” (reverse water flow from the gills). Morphological effects consisted of mucous secretions and external hemorrhages at all exposures. Since CS is a cutaneous irritant and causes hydropic degeneration in the epithelial basil cell layers, the increased mucus secretion is perhaps due to the irritant effects of CS (Pearson, 1975). In contrast, when these exposure concentrations were lowered to 1.6, 2.5, and 4.0 mg/L, no adverse behavior was observed; however, there were mucus secretions. Other studies (Keller et al., 1986) defined a lethal threshold concentration of 3.9 mg/L for CS exposures to the mumichog. Pearson (1975) reported the times to 50% mortality with CS were 5546 min at 4.0 mg/L, 4198 min at 6.3 mg/L, and 1591 min at 10 mg/L for the mumichog. When malononitrile was investigated the times to 50% mortality for the mumichog were 5033 min at 2.5 mg/L, 3184 min at 4.0 mg/L, and 2559 min at 8.5 mg/L (Pearson, 1975). The rainbow trout exhibited greater sensitivity and lethality than the mumichog. For CS at 4.0 mg/L, the median period of survival was about 1500 min for the rainbow trout, compared to the 5546 min for the time to 50% mortality for the mumichog. For o-chlorobenzaldehyde, the mumichog showed no abnormal behavior at 10 mg/L, while the median period of survival was about 400 min for the rainbow trout. In the investigation of Abram and Wilson (1979), the median period of survival for the rainbow trout was about 3000 min at a malononitrile concentration of 4 mg/L, while for the mumichog the time to 50% mortality was 3184 min at the same concentration. Thus, the time with respect to malononitrile is similar. Similarly, CS ecotoxic effects were reviewed for goldfish, Carassius auratus (Linnaeus) by Pearson (1975). The median lethal time (Lt50) for 6 mg/L of CS ranged from 3.3 to 21.8 h, and a higher concentration of 10 mg/L showed toxic effects at 2.7–5.3 h. Observed symptoms included increased mucous membrane secretions, and histological evaluations further showed scattered hemorrhages in the dorsolateral musculature as well as epithelium sloughing (Pearson, 1975).


RIOT CONTROL AGENTS

The aquatic toxicity to phytoplankton has been investigated using three species of duckweeds (Wolffia papulifera, Lemma perpusilla, and Spirodela oligorhiza). Schott and Worthley (1973) reported that colony growth rates of all three species of duckweeds were significantly reduced when concentrations of CS were at or above 5 mg/L. At 50 mg/L, all colonies died. The toxicity of breakdown products was also investigated; malononitrile was found to be more toxic than o-chlorobenzaldehyde. Effects were detected at concentrations of 5 mg/L for each of these breakdown products.

16.2.3 Environmental fate in the atmosphere The fate of CS in the atmosphere has been evaluated using structure estimation methods and information on its hydrolysis when present with water. A half life of 110 h in the atmosphere is estimated by Syracuse Research Corporation based on an assumed concentration of 500,000 hydroxyl radicals per cubic cm (Meylan and Howard, 1993; Toxnet, 2001b). There are three processes that will reduce the concentration of CS in the atmosphere. They are reaction with hydroxyl radicals, hydrolysis by water in the atmosphere and deposition of CS that is present in particulate matter. At 20C, the vapor pressure of CS is 3.4 105 mmHg (Toxnet, 2001b), and the corresponding gas phase concentration of CS is 0.35 mg/m3. Thus, concentrations in the air that are larger than this at 20C include a particulate phase. The vapor pressure increases with temperature, and it is 5–7 mmHg at 60C (Material Safety Data Sheet, Edgewood Arsenal).

16.3 2-CHLOROACETOPHENONE CN which is 2-chloroacetophenone is a solid at room temperature. There is limited data on its solubility in water; reported values range from 0.1 to 1 g/L (Daeniken, 1983; Argonne, 2000). The estimation methods of Yalkowsky et al. (1983) give a value of 1 g/L when a value of log Kow of 2.09 and a melting point of 54C are used (Compton, 1988; Prager, 1995). CN is a solid at normal environmental temperatures, and it is stable when stored in dry containers. The fate of CN in soil depends on soil moisture because the solid particles are relatively stable in dry soil while degradation is expected in wet soil where microorganisms are active. If a large quantity of CN is dumped in solid form in a landfill, one would expect that some would remain in solid form for many years because of the very slow dissolution process in unsaturated soil. There are three degradation processes that have been identified for CN. Hydrolysis of CN to HCl and hydroacetophenone (Compton, 1988) or acetophenone (Smolen et al., 1999) has been reported. Smolen et al. (1999) reported that acetophenone was formed when ferrous iron (Fe II) was present in the solution. They also reported that the rate of hydrolysis was very slow without the ferrous iron, and Compton (1988) also reports that CN is not readily hydrolyzed. The rate of hydrolysis appears to depend on pH and temperature. Compton (1988) indicates that alkaline solutions and steam can be used for decontamination of confined spaces. Smolen et al. (1999) report rate constant data in which the rate increases with temperature. The rate of hydrolysis increases at higher pH according to Danto (1987). The second reaction that has been reported is the microbial reduction of CN to 2-chloro-1-phenyl ethanol (Imuta et al., 1980; Smolen et al., 1999). Dehydrogenase enzymes appear to be active in the reduction as the rate is reported to be slow without dehydrogenase enzymes even when nicotinamide adenine dinucleotide (NADH) is present. Smolen et al. (1999) observed that CN disappeared in their experiments by a third process. They attribute this to reaction with sulfide and report facile disappearance of CN when sulfide is present in their system. They also point out that the fate of related



compounds such as chloroacetanilides have been extensively investigated. Field and Thurman (1996) have reviewed the literature on glutathione conjugation and contaminant transformation. Thurman et al. (1996) report that alachlor and glutathione enzymatically form alachlor–glutathione conjugate which then is converted to a sulfonate, which can be found in surface waters in regions of the farm belt where alachlor is applied. Zablotowicz et al. (1995) have investigated the activity of the glutathione-S-transferase enzymes in microbial populations and report that higher activities were found in gram-negative bacteria. Glutathione-S-transferase enzymes are present in plants (Hatzios, 2001) and animals (Sharp, 1988). These enzymes rapidly transformed alachlor to its glutathione conjugate in rats, mice, and monkeys when experiments were conducted in vitro. Since alachlor and the other chloroacetanilides have the same chloro ketone functional group as CN, similar results (formation of a CN–glutathione conjugate) are expected for CN. Habig et al. (1974) report that there are several different glutathione-S-transferases, which are functional enzymes for the conjugation reactions. They investigated four different ones that are present in rat livers. More recently, Vuilleumier (2001) reports that several dozen sequences of glutathioneS-transferases are now known. These enzymes are known to catalyze a wide range of glutathione dependent reactions. Stamper et al. (1997) report that sulfur reducing bacteria can transform alachlor, propachlor, and metolachlor. They also found that the transformation could be duplicated with sodium sulfide under abiotic conditions. The work of Smolen et al. (1999) would suggest that sulfur reducing bacteria should be able to transform CN, as well.

16.3.1 Environmental fate in soil The experiments of Smolen et al. (1999) with sediments from four different locations show that CN is transformed in soil systems. As shown in Table 16.1, which is based on the results of Smolen et al. (1999), all three of the degradation processes above appear to be active if one assumes that the last column includes glutathione conjugation. The results in the first column are expected to vary with pH and ferrous iron concentration; values of both of these vary from sediment to sediment as shown in Table 1 of Smolen et al. (1999). The half time for degradation of the CN which is based on the estimated first order kinetic constants reported by Smolen et al. (1999) varies from 1.7 h for Institute Marsh to 48 h for Cherokee Park. The time required for degradation of CN in soil has been estimated by Howard et al. (1991). The half-life under aerobic conditions is estimated to range from 168 h to 672 h.

TABLE 16.1 Fate of CN in four different sediments. Values of degradation products are in percentc Sediment

Acetophenonea

2-CPEb

Other formsc

Cherokee Park Rock Creek Young’s Bay Institute Marsh

50 45 20 20

10 35 5 3

40 20 75 77

Notes a Includes acetophenone that was converted to sec-phenethyl alcohol. b Values in columns one and two are from results of Smolen et al. (1999). Values in the other column are by difference. In column 2, 2-CPE refers to 2-chloro-1-phenyl ethanol. c Includes products produced by glutathione conjugation.


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These values are longer than the experimental values above; however, the experiments by Smolen et al. (1999) only address the first steps of the degradation process. The above rates of degradation can be compared with those for alachlor, metolachlor, and acetochlor. Under field conditions, Sharp (1988) reports half-lives of two to four weeks (336–672 h), and LeBaron et al. (1988) report half-lives of 5 to 10.1 weeks (840–1697 h) for metolachlor. Miller et al. (1997) report a half-life of 7.3 weeks (1226 h) for metolachlor. Feng (1991) reports half-lives of one week (168 h) for acetochlor and 30 min for the S-glutathione conjugate of acetochlor in laboratory soil studies. Based on this information, CN is expected to biodegrade in moist soil, and the half-life is expected to be less than 672 h when all of the nutrients needed for biodegradation are present.

16.3.2 Environmental fate in water The experiments of Smolen et al. (1999) were carried out with solid contents ranging from 2% to 10%. Thus, while the solid sediments provided the microbial cultures that grew in the mixture, the environment for the cells included an aqueous phase, as well as solid surfaces for adsorption. One would expect similar rates of biodegradation in water where the conditions are similar except for the absence of soil. Howard et al. (1991) report similar estimates of half-life from 168 h to 672 h for aerobic degradation in surface waters and other aerobic waters. They report estimated values ranging from 672 h to 2688 h for the half-life for anaerobic aqueous biodegradation. In surface waters, there can be disappearance due to volatile losses to the atmosphere. The vapor pressure of CN is about 0.0041 mmHg at 20C, 0.0054 mmHg at 25C, and 0.152 mmHg at 52C (Compton, 1988; Toxnet, 2001a). Based on an estimated value for the Henry’s law constant of 0.0035 L atm/mol, the estimated half-life in a river is 14 days (336 h), and it is 110 days (2640 h) for a lake (Toxnet, 2001a). Thus, in surface waters, degradation processes and losses due to volatilization are both expected to contribute to the disappearance. Experimental data on aquatic toxicity is very limited. While the solubility of CN in water is quite low, a saturated solution of CN would be expected to exhibit some toxicity to sensitive species. Imuta et al. (1980) added 100 mg of CN to 250 ml of broth in their experiments. This would give a concentration of 400 mg/L if all of the CN dissolved in the broth. There was no mention of any inhibition at these conditions. Thus, microbial growth in saturated solutions of CN is expected provided the essential nutrients are present.

16.3.3 Environmental fate in the atmosphere The reported fate of CN in the atmosphere is based on estimated values. These include a half-life of 8 days (Toxnet, 2001a) and values which range from 3.1 days to 31 days (Howard et al., 1991). These estimates are based on reaction with hydroxyl radicals in the atmosphere.

16.4 DIBENZ[b,f ]1:4-OXAZEPINE The RCA dibenz[b,f]1:4-oxazepine (CR) has a solubility in water of 0.35 mmol/L or 68.2 mg/L. It is a solid at room temperature. It melts at 72C and has a boiling point of 335C. It has a vapor pressure of 0.00059 mmHg at 20C (U.S. Army, 1995). No information was found in the published literature on the remediation or biodegradation of CR in soil. Because of its limited solubility in water, one would expect quantities of the solid material



to dissolve slowly into soil water and to remain in solid form in relatively dry unsaturated soil. There is literature on the fate of CR in mammalian systems (Balfour, 1978; Harrison et al., 1978; French et al., 1983a,b; Furnival et al., 1983). French et al. (1983a) have identified 10 metabolic products using radiochemically labeled carbon samples of CR in rats, rhesus monkeys, and guinea-pigs. They report that there are several metabolic pathways, and that CR is converted to the lactam, then to hydroxylactams, and then to the hydroxylactam sulfates. The 4th, 7th, and 9th positions have been the locations where the oxygen containing groups have been found in urine with the largest fraction being 7-hydroxylactam in guinea-pig and monkey, and 7-hydroxylactam sulfate in the rat. These transformations occur rapidly and the half-life of CR in the rat is less than one hour. The liver is the primary location where the transformations occur. Furnival et al. (1983) have conducted in vitro experiments and established that CR is oxidized to the lactam in the cytosol of whole liver homogenate. The enzyme involved has properties characteristic of an aldehyde oxidase. In the presence of an added NADPHregenerating system, the amino alcohol of CR which is 2-amino-2’hydroxymethyl diphenyl ether was formed and the percentage increased with the concentration of CR. Furnival et al. indicate that the enzyme that produces the amino alcohol of CR closely resembles the aldehyde reductases which have a wide distribution in nature. Dihydro CR is also formed in buffer containing the NADPH-regenerating system consisting of NADP, glucose 6-phosphate, glucose 6-phosphate dehydrogenase, and magnesium chloride. This information suggests that transformations of CR should be expected to occur in nature in biological organisms other than mammalian systems. Haley et al. (1990), Johnson et al. (1990), and Landis et al. (1993) have investigated the toxicity and degradation of CR in aqueous media designed to mimic a freshwater ecosystem. They isolated the bacteria Alcaligenes denitrificans denitrificans, CR-1 (ATCC # 53957) which biodegrades CR. They propose a degradation pathway with o-nitrophenol and o-cresol as the first degradation products with a single aromatic ring. Catechol and 3-methylcatechol are proposed subsequent degradation products prior to ring breakage. Haley et al. (1990) reported that CR-1, the bacteria that they isolated, was able to biodegrade o-nitrophenol, catechol, and 3-methylcatechol. There is evidence for biodegradation of o-cresol by other microorganisms in the published literature (Erickson and Fan, 1988). In the experiments that were conducted, concentrations of CR up to 200 mg/L were investigated even though this required ethanol as a cosolvent. Starting with a concentration of 6.5 mg/L, more than 95% of the CR was biodegraded or transformed during an 18-day experiment (Landis et al., 1993). When an initial concentration of 200 mg/L was employed, it took 22 days for CR-1 to degrade the CR to a concentration below the detection limit of approximately 1 mg/L. The concentrations of CR that were investigated in the biodegradation experiments were larger than those which exhibited toxicity in these same microcosms. Johnson et al. (1990) reported a 24-h median effective concentration (EC50) of 1.48 mg/L and a 48-h concentration of 0.94 mg/L for CR for acute toxicity of Daphnia magna. They also reported the total number of young produced and daphnid length at the end of a 21-day test for CR concentrations from zero (control) to 0.50 mg/L. The 21-day inhibition median concentration (IC50) was reported to be 1.8 mg/L for a linear model and 2.2 mg/L for the exponential model. An investigation of the toxicity of CR for Pimephales promelas (fathead minnows) resulted in values ranging from 2.5 to 3.4 mg/L for the median lethal concentration (LC50). For Ankestrodesmus falcatus, algal growth inhibition was investigated, and the median inhibiting concentration in which growth was inhibited by 50% was reported to range from 1.9 to 6.7 mg/L. Harrison et al. (1978) have reported that arene oxides are formed as intermediates when metabolic products of CR are oxidized to 7-hydroxylactam. The metabolic formation of arene oxides associated with the oxidation of aromatic compounds to phenols is known


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to explain some of their toxic and carcinogenic properties (Jerina and Daly, 1974). The formation of arene oxides is an undesirable aspect associated with the degradation of CR. These results show that CR is biodegradable and that it is transformed in microbial and mammalian species. One would expect that it might be transformed in other environments as well.

16.5 ENVIRONMENTAL MANAGEMENT OF IRRITANTS CONTAINING PEPPER AND/OR OLEORESIN CAPSICUM (OC) There are a number of products on the market that are produced from natural plant materials and used as irritants. Black pepper is the dried immature berry of Piper nigrum L., while white pepper is the dried mature berry of Piper nigrum L. (Scott and Kennedy, 1973). Oleoresin capsicum is a product made from dried ripe fruits of the genus capsicum; cayenne pepper, red pepper, and paprika are common products made from capsicum. Oleoresin capsicum is produced by extraction of the pungent compounds using a volatile solvent such as hexane that can be removed by evaporation (Bosland and Votava, 2000: 160). The concentrated pungent compounds can then be used in food, pharmaceutical, or irritant applications. Since irritants made from these natural materials have very limited patent protection, there are many different products that are produced and marketed. Most of them contain compounds from the dried ripe fruits of the genus capsicum.

16.5.1 Capsicum chemistry The pungent compounds in capsicum are called capsaicinoids. Capsaicin is the most abundant of these; dihydrocapsaicin is often next in abundance, and the two compounds often make up more than 80% of the capsaicinoids (Cordell and Araujo, 1993). The chemistry of capsaicinoids is reviewed by Purseglove et al. (1981) and by Govindarajan (1987). Nordihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin are often present, but in lesser amounts (Govindarajan et al., 1988). The structure of these compounds is shown in Figure 16.1. Table 16.2 presents some representative data on the percentages of each compound in selected products that were reviewed by Govindarajan et al. (1988). As shown in Table 16.2, the pungent capsaicinoids are not the only compounds that are extracted when an organic solvent is used. The mass fraction of capsaicinoids is often less than 4% in the organic phase that is extracted. After removal of the seeds, the fruit that is crushed often contains from 0.4 to 1.3 weight per cent capsaicinoids (see Table 12 in Govindarjan et al., 1988). Most of the pungent capsaicinoids are found in the dissepiments (partitions) within the fruit (Purseglove et al., 1981). The capsicum fruit contains pigments which impart color to products such as paprika. Capsanthin and capsorubin are red pigments which are found in the pericarp of the fruit at less than 1% by weight (Govindarajan, 1987). Capsanthin is a keto-carotenoid containing a cyclopentane ring. Beta-carotene is also present in the pericarp of the fruit of the capsicum at about 0.1% by weight or less. These organic pigments are extracted when oleoresin is produced. Volatile organic compounds (VOCs) are also extracted when the oleoresin is produced; however, some may be lost when the organic solvent is removed by evaporation. Keller et al. (1981) has analyzed the volatile compounds that are found in oleoresin capsicum products. His list of identified compounds includes 10 alcohols, 15 aldehydes and ketones, 12 carboxylic acids, 20 esters, and 12 hydrocarbons. Govindarajan (1987) has reviewed



TABLE 16.2 Relative abundance of capsaicinoids in commercial samples of crystalline capsaicinoids and capsicum oleoresins Sample

Capsaicinoids total (%)

C

DC

NDC

HDC

HC

Pflatz & Baur Fluka Fluka 51805 Sigma Sigma Kalsec, oleoresin Kalamazoo, oleoresin Kalamazoo, oleoresin Manheimer, oleoresin Strange, oleoresin

100 100 100 100 100 2.27

55.0 54.9 82.1 88.2 47.8 63.4

29.1 30.0 14.6 10.4 46.7 31.8

13.2 12.6 3.3 1.4 5.7 3.1

2.0 1.9 — — — 1.5

0.8 0.5 — — — 0.3

1.52

62.5

32.2

5.3

—

—

3.75

50.3

42.0

7.7

—

—

4.00

51.8

36.7

8.0

2.3

1.2

2.94

49.0

32.3

13.3

4.4

1.0

Name

Structural formula

Capsaicin Dihydrocapsaicin Nordihydrocapsaicin Homodihydrocapsaicin Homocapsaicin Nonanoic acid vanillylamide Decanoic acid vanillylamide

(CH3)2 • CH • CH = CH • (CH2)4 – CO – R (CH3)2 • CH • (CH2)6 – CO – R (CH3)2 • CH • (CH2)5 – CO – R (CH3)2 • CH • (CH2)7 – CO – R (CH3)2 • CH • CH = CH • (CH2)5 – CO – R CH3 • (CH2)7 • CO – R CH3 • (CH2)8 – CO – R

where R is

NH

CH2

OH OCH3

Figure 16.1: Capsaicinoids in Capsicum species (Purseglove et al., 1981: 376;

Govindarajan et al., 1988: 216).

information on the VOCs in capsicum products. Purseglove et al. (1981) indicate that the volatile oils are largely found in the pericarp, and that the amount of volatile oils ranges from about 0.1% to 2.6%.

16.5.2 Biodegradation of capsicum compounds The literature associated with microbial processes with compounds found in capsicum as substrates is mostly concerned with preservation of product quality. Govindarajan (1985,


Note Values are rounded; C – capsaicin, DC – dihydrocapsaicin, NDC – nordihydrocapsaicin, HDC – homodihydrocapsaicin, and HC – homocapsaicin. Govindarajan et al. (1988: 260).

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1986) makes several references to microbial degradation and to microbial numbers in capsicum products. For example, “The temporary storage of high moisture chilies in bags could start a deteriorative process affecting color and microbiological quality before central drying.” (Govindarajan, 1985). The literature gives significant attention to drying processes and the need to reduce the moisture content prior to storage in order to prevent microbial degradation. Examination of the dried fruit shows that both bacteria and molds are present with numbers ranging from about 29,000 to 15,000,000 per gram of fruit for bacteria and 500 to 1,500 per gram for molds (Govindarajan, 1985). Molds that produce aflatoxins have been identified (Flannigan and Hui, 1976), and they have been shown to grow on red peppers and to produce aflatoxins (Schindler and Eisenberg, 1968). The quantities of aflatoxins present in commercial products are generally quite small (Scott and Kennedy, 1973). Thus, the general evidence indicates that these natural products are biodegraded and that both bacteria and molds are involved in their biodegradation. Most of the biodegradation appears to be under aerobic conditions. Storage studies have shown that dried products stored in a nitrogen atmosphere retain their color and product quality better than products stored in air (Govindarajan, 1987). Some information on the oxidation pathways has been reported (Chen and Gutmanis, 1968; Philip and Francis, 1971). Spices have been used to inhibit microbial degradation in foods. Govindarajan et al. (1988) have reviewed the literature on antimicrobial properties of capsicum products. Their review indicates that phenolics in the volatile oils and capsaicinoids do inhibit microbial activity; however, the inhibition appears to be limited to selected species. Capsaicinoids at 100 mg/L did not inhibit growth of Lactobacillus casei (bacteria), Saccharomyces cerevisiae (yeast), and Aspergillus niger (fungi). The time required for fungal cultures to degrade the capsaicinoids was about ten days (Govindarajan et al., 1988). The concentration of the capsaicinoids affects the extent of the inhibition. Govindarajan et al. (1988) conclude their review as follows: “It can be concluded that the antimicrobial activity of the spice capsicum is not significant.” Since the capsaicinoids have limited solubility in water, they will have limited antimicrobial activity in aqueous solutions because of this.

16.5.3 Oleoresin capsicum ecotoxicity Because OC is biodegradable, it does not require any decontamination protocols (Edwards et al., 1997). OC has been used as a bird repellent by the United States Environmental Protection Agency (EPA); thus, it is assumed that birds as well as other terrestrial species will avoid excessive and prolonged exposure therefore minimizing any potential risk. Additional studies reported that capsaicin did not repel birds that do not recognize capsaicin as “hot” due to their lack of capsaicin sensitive receptors (US EPA, 1992). The effect of OC on aquatic life is limited. In comparison to those mobile terrestrial animals such as birds, fish and other aquatic species unfortunately have limited mobility and are not able to avoid chemicals that have been dispersed in their habitat. EPA expressed uncertainty of OC potential risk due to the limited toxicity information for aquatic species and the inability to estimate exposures. Recommended precautionary methods are therefore restricted to limiting or reducing the usage of OC in aquatic environments (US EPA, 1992). When capsaicin is hydrolyzed in the presence of the enzyme Candida antarctica lipase, the initial metabolic products vannillylamine and 8-methyl-6-trans-nonenoic acid are formed which are further degraded to vanillyl alcohol, vanillic acid, and vanillin (Duarte et al., 2000). Some biological effects were observed in fathead minnows exposed to vanillan (3-methoxy-4-hydroxy-benzaldehyde, vanillicaldehyde). Studies indicated a lethal



concentration at which 50% of the test subjects died (LC50) when exposed to OC for 1, 24, 48, 72, and 96 h to be 173, 131, 123, 121, 121 mg/L (Verschueren, 1983).

16.6 IRRITANTS AND CONFINED ENVIRONMENTS Irritants may be employed in interior or confined environments to encourage individuals to leave that environment. The solid particles will release the irritant to the gas phase until phase equilibrium is established. In Table 16.3, equilibrium gas phase concentrations at 25C are compared to the operational and limiting values reported by Keller et al., (1986). For all three irritants, the equilibrium concentration in air at 25C is larger than the threshold value, where eye irritation is observed to occur. For CN, the gas phase equilibrium concentration of 45 mg/m3 at 25C is close to the reported effective concentration of 35 mg/m3. For CS and CR, the gas phase equilibrium values are smaller than the reported effective concentrations. Often heat is used to increase the gas phase concentration. For a time period of ten minutes, the estimated lethal concentrations are 1000 mg/m3 for CN, 6000 mg/m3 for CS, and 10,000 mg/m3 for CR (Keller et al., 1986). These values are significantly larger than the gas phase equilibrium value at 25C.

16.7 SORPTION ONTO BUILDING MATERIALS 16.7.1 Sorption equilibrium Organic compounds, that are present as vapors in air, adsorb onto surfaces. The equilibrium isotherm (Levine, 1995) describes the relationship between the partial pressure of the volatile organic compound (VOC) in the gas phase and adsorbed concentration on the solid surface. The adsorption isotherm is obtained by measuring the gas phase and adsorbed concentrations at equilibrium for several different concentrations of the VOC at a given temperature. The adsorption equilibrium relationship depends on temperature and pressure. Most adsorption is physical and it is reversible. Compounds involved in chemisorption are changed chemically and the product formed may desorb or remain on the surface. The adsorption equilibrium is a function of temperature and pressure. Increasing the temperature generally causes some of the VOC to leave the solid surface and go into the

TABLE 16.3 Comparison of gas phase equilibrium concentrations with threshold, effective, and lethal concentration reported by Keller et al. (1986)

Gas phase equilibrium concentration at 25C (mg/m3) Eye irritation threshold-aerosol (mg/m3) Aerosol effective concentration (mg/m3) Estimated lethal dosage (mg/m3)a

CN

CS

CR

45

0.71

0.63

0.3

0.004

0.002

35

5

1

1000

6000

10,000

Note a Exposure duration of 10 mins.


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air. Increasing the pressure generally causes some of the VOC to adsorb onto the solid adsorbent. Carpets, drapes, wall materials, and ceiling materials may be manufactured from one or more compounds. The organic fraction in the building material is often the most attractive location for adsorption. The extent of adsorption depends on the surface area that is available to the VOC. The VOC may also be present as a solute in the organic solid phase. Sorption refers to the combined effects of adsorption and absorption where the VOC is physically present on the solid surfaces and is also dissolved in the interior of the solid. Each VOC has several physical properties that affect sorption to building materials. These include vapor pressure, solubility in water, and octanol/water partition coefficient (Kow). Since vapor pressure increases with temperature, the sorption equilibrium concentration associated with the solid decreases as temperature and vapor pressure increases for a given VOC concentration in the gas phase (Won et al., 2001). Those VOCs with large values of Kow are strongly sorbed to the organic portions of building materials. An et al. (1999) found that carpet samples were excellent sorbents for the five organic compounds that were tested. The VOCs, ethylbenzene, cyclohexanone, 1,4-dichlorobenzene, benzaldehyde, and dodecane have large values of Kow. An et al. found that the adsorption equilibrium concentration associated with the solid phase was much larger for carpet samples compared to vinyl tile, painted dry wall, and ceiling tile. Won et al. (2001) divided the ocatanol/water partition coefficient by the Henry’s law constant to obtain an octanol/air partition coefficient. Using eight different VOCs and 12 different solids, they demonstrated that the sorbed concentration at equilibrium is proportional to the octanol/air partition coefficient.

16.7.2 Sorption and desorption processes The processes of sorption to solids and desorption from solids are rate processes that depend on concentration gradients. These include the gas phase concentration gradient external to the solid and concentration gradients within the solid. Transport within the solid is primarily by diffusion. Gas phase diffusivities are much larger than diffusivities in liquids and solids (Cussler, 1984). Jogensen et al. (2000) and Topp et al. (2001) have reported that the rate process of desorption of VOCs from building materials may be diffusion limited. Jorgensen et al. have reviewed earlier modeling efforts, and he has presented a simple model which includes sorption, desorption, and diffusion. The rate of sorption is proportional to the gas phase concentration and the surface area for sorption. The rate of desorption is proportional to the sorbed concentration and the surface area. The rate of transport by diffusion is proportional to the diffusivity, area, and concentration gradient. Meininghaus et al. (2000) have measured diffusion coefficients in several building materials and have found that in some cases the effective diffusion coefficients are only one order of magnitude smaller than those for the VOC in air.

16.7.3 Sorption of mixtures Jorgensen and Bjorseth (1999) have investigated the sorption of mixtures of VOCs. They reported that the results were nearly additive when values for the VOCs tested individually were compared to the result from adding both VOCs at the same time. Won et al. (2000) have shown that relative humidity affects the sorption process for 2-propanol which is highly soluble in water, but there is little or no effect for nonpolar VOCs.



16.8 CONCLUSIONS Riot control agents can be degraded by microbial processes in soil and water. Because of their low solubility in water and low vapor pressure, they can persist in dry soil for a much longer period of time. Experiments on the toxicity in aquatic environments show that many of these compounds can impact the health of aquatic species. Thus, wash water from sites where RCAs are used should be treated prior to discharge to any stream.

ACKNOWLEDGMENT This work was partially supported by the Department of the Navy, Naval Surface Warfare Center, Dahlgren Laboratory. The content of the information does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.

REFERENCES ABRAM, F.S.H. and WILSON, P. (1979) The acute toxicity of cs to rainbow trout, Water Research 13: 631–635. ALEXANDER, M. (1999) Biodegradation and bioremediation, 2nd edn, New York: Academic Press. AN, Y., ZHANG, J.S., and SHAW, C.Y. (1999) Measurment of VOC adsorption/desorption characteristics of typical interior building materials, HVAC&R Research 5: 297–316. Argonne National Laboratory (2000) Remedial Investigation Report for J-Field, Aberdeen Proving Grounds, Maryland, Report ANL/EAD/TM-80, U.S. Department of Energy, Office of Scientific and Technical Information, Oak Ridge, TN 37831–0062; available electronically at http://www.doe.gov/bridge Army (1995) Potential Military Chemical/Biological Agents and Compounds, PCN 320 008457 00, Headquarter, Dept. of Army, Washington, DC; U.S. Gov. Printing Office 1995 0-388-421 (02448); http://www.radiantgames.com/nbcwar/fm39.pdf BALFOUR, D.J.K. (1978) Studies on the uptake and metabolism of dibenz(b,f)-1,4-oxazepine (CR) by guinea-pig cornea, Toxicology 9: 11–20. BOSLAND, P.W. and VOTAVA, E.J. (2000) Peppers: Vegetable and Spice Capsicums, New York: CABI Publishing. CHEN, S.L. and GUTMANIS, F. (1968) Auto-oxidation of extractable color pigments in chili pepper with special reference to ethoxyquin treatment, Journal of Food Science 33: 274–280. COMPTON, J.A.F. (1988) Military Chemical and Biological Agents, Caldwell, New Jersey: Telford Press. CORDELL, G.A. and ARAUJO, O.E. (1993) Capsaicin: review article: identification, nomenclature, and pharmacotherapy, The Annals of Pharmacotherapy, 27, March. CUSSLER, E.L. (1984) Diffusion Mass Transfer in Fluid Systems, Cambridge, UK: Cambridge University Press. DAENIKEN, A. (1983) Bibliography Over the Toxicology of Tear Gases Chloroacetophenone (CN), O-Chlorobenzylidene Malononitrile (CS), and Dibenz(b,f )-1,4-oxazepine (CR), Poison Department of the Federal Office for Health Service, Berne. DANTO, B.L. (1987) Medical problems and criteria regarding the use of tear gas by police, American Journal of Forensic Medicine and Pathology, 8: 317–322. DUARTE, D.R., CASTILLO, E., BARZANA, E., and LOPEZ-MUNGUIA, A. (2000) Capsaicin hydrolysis by Candida antarctica lipase, Biotechnology Letter, 22: 1811–1814. EDWARDS, S.M, GRANFIELD, J., and ONNEN, J. (1997) National Institute of Justice, Research in Brief, Evaluation of Pepper Spray. Feb. 1997.


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ENGESSER, K.H. and SCHULTE, P. (1989) Degradation of 2-bromo-, 2-chloro- and 2-fluorobenzoate by Pseudomonas putida CLB 25, FEMS Microbiology Letters, 60: 143–147. ERICKSON, L.E. and FAN, L.T. (1988) Anaerobic degradation of toxic and hazardous wastes. In: L.E. ERICKSON, and D.Y.C. FUNG (eds), Handbook on Anaerobic Fermentations, New York: Marcel Dekker, pp. 695–732. FENG, P.C.C. (1991) Soil transformation of acetochlor via glutathione conjugation, Pesticide Biochemistry and Physiology, 40: 136–142. FETZNER, S. (1998) Bacterial dehalogenation, Applied Microbiology and Biotechnology, 50: 633–657. FETZNER, S. and LINGENS, F. (1994) Bacterial dehalogenases: biochemistry, genetics, and biotechnological applications, Microbiological Reviews, 58: 641–685. FETZNER, S., MULLER, R., and LINGENS, F. (1989) Degradation of 2-chlorobenzoate by Pseudomonas cepacia 2CBS, J. Biological Chemistry. Hoppe-Seyler, 370: 1173–1182. FIELD, J.A. and THURMAN, E.M. (1996) Glutathione conjugation and contaminant transformation, Environmental Science and Technology. 30: 1413–1418. FLANNIGAN, B. and HUI, S.C. (1976) The occurrence of aflatoxin producing strains of Aspergillus flavus in the mold floras of ground spices, Journal of Applied Bacteriology, 41: 411–418. FRENCH, M.C., HARRISON, J.M., INCH, T.D., LEADBEATER, L., NEWMAN, J., UPSHALL, D.G., and POWELL, G.M. (1983a) The fate of dibenz(b,f )-1,4-oxazepine (CR) in the rat, rhesus monkey, and guinea-pig. Part I. Metabolism in vivo, Xenobiotica, 13: 345–359. FRENCH, M.C., HARRISON, J.M., NEWMAN, J., UPSHALL, D.G., and POWELL, G.M. (1983b) The fate of dibenz(b,f )-1,4-oxazepine (CR) in the rat. Part III. The intermediary metabolites, Xenobiotica, 13: 373–381. FURNIVAL, B., HARRISON, J.M., NEWMAN, J., and UPSHALL, D.G. (1983) The fate of dibenz(b,f )-1,4oxazepine (CR) in the rat. Part II. Metabolism in vitro, Xenobiotica 13: 361–372. GOVINDARAJAN, V.S. (1985) Capsicum production, technology, chemistry, and quality. Part I. History, botany, cultivation, and primary processing, CRC Critical Reviews in Food Science and Nutrition, 22: 109–176. GOVINDARAJAN, V.S. (1986) Capsicum production, technology, chemistry and quality. Part II. Processed products, standards, world production, and trade, CRC Critical Reviews in Food Science and Nutrition, 23: 207–288. GOVINDARAJAN, V.S. (1987) Capsicum production, technology, chemistry, and quality. Part III. Chemistry of the color aroma, and pungency stimuli, CRC Critical Reviews in Food Science and Nutrition, 24: 245–354. GOVINDARAJAN, V.S., RAJALAKSHMI, D., and CHAND, N. (1988) Capsicum production, technology, chemistry, and quality. Part IV. Evaluation of quality, CRC Critical Reviews in Food Science and Nutrition, 25: 185–283. HABIG, W.H., PABST, M.J., and JAKOBY, W.B. (1974) glutathione-s-transferases: the first enzymatic step in mercapturic acid formation, Journal of Biological Chemistry, 249: 7130–7139. HALEY, M.V., VICKERS, E.L., CHENG, T.C., DEFRANK, J., JUSTUS, T.A., and LANDIS, W.G. (1990) Biodegradation and reduction in aquatic toxicity of the persistent riot control material 1,4-dibenz-oxazepine. In: W.G. LANDIS, and W.H. VAN DER SCHALIE (eds.), Aquatic Toxicology and Risk Assessment, Vol. 13, ASTM STP 1096, Philadelphia, PA: American Society for Testing Materials, pp. 60–76. HARRISON, J.M., CLARKE, R.J., INCH, T.D., and UPSHALL, D.G. (1978) The metabolism of dibenz(b,f)-1,4oxazepine (CR): in vivo hydroxylation of 10,11 dihydroxydibenz(b,f)-1,4-oxazepine-11-(1OH)-one and the NIH shift, Experientia 34: 698–699. HATZIOS, K.K. (2001) Functions and regulation of plant glutathione-s-transferases. In: J.C. Hall, R.E. HOAGLAND, and R.M. ZABLOTOWICZ (eds), Pesticide Biotransformation in Plants and Microorganisms, ACS Symposium Series 777, Washington, DC: American Chemical Society, pp. 218–239. HOOK, I.L., RYAN, S., and SHERIDAN, H. (1999) Biotransformation of aromatic aldehydes by five species of marine microalage, Phytochemistry 51: 621–627.



HOWARD, P.H., BOETHLING, R.S., JARVIS, W.F., MEYLAN, W.M., and MICHALENKO, E.M. (1991) Handbook of environmental degradation rates, Boca Raton, FL: Lewis Publishers. IMUTA, M., KAWAI, K.I., and ZIFFER, H. (1980) Product stereospecificity in the reduction of alphahaloaryl ketones, Journal of Organic Chemistry, 45: 3352–3355. JERINA, D.M. and DALY, J.W. (1974) Arene oxides: A new aspect of drug metabolism, Science, 185: 573–582. JOHNSON, D.W., HALEY, M.V., and LANDIS, W.G. (1990) The aquatic toxicity of the sensory irritant and riot control agent dibenz(b,f )-1,4-oxazepine (CR). In: W.G. LANDIS and W.H. VAN DER SCHALIE (eds), Aquatic Toxicology and Risk Assessment, Vol. 13, ASTM STP 1096, Philadelphia, PA: American Society for Testing Materials, pp. 176–188. JORGENSEN, R.B. and BJORSETH, O. (1999) Sorption behaviour of volatile organic compounds on material surfaces – the influence of combinations of compounds and materials compared to sorption of single compounds on single materials, Environment International, 25: 17–27. JORGENSEN, R.B., DOKKA, T.H., and BJORSETH, O. (2000) Introduction of a sink-diffusion model to describe the interaction between volatile organic compounds (VOCs) and material surfaces, Indoor Air, 10: 27–38. KELLER, U., FLATH, R.A., MON, T.R., and TERANISHI, R. (1981) Volatiles from red pepper (Capsicum sp.). In: R. TERANISHI and H. BARRERA-BENITEZ (eds), Quality of Selected Fruits and Vegetables in North America, ACS Symposium Series vol. 170, pp. 137–146. KELLER, W.C., ELVES, R.G., and BONNIN, J.C. (1986) Assessment of CS environmental toxicity at Eglin AFB, FL, AD-A171685, Defense Technical Information Center, 8725 John J. Kingman Road, Suite 0944, Fort Belvoir, VA, 22060. LANDIS, W.G., CHESTER, N.A., and Haley, M.V. (1993) Evaluation of the ability of Alcaligenes denitrificans CR-1 to degrade the riot control agent CR using the standardized aquatic microcosm. In: LANDIS, W.G., HUGHES, J.S., and LEWIS, M.A. (eds), Environmental Toxicology and Risk Assessment, ASTM STP 1179, PA: American Society for Testing Materials. LEBARON, H.M., MCFARLAND, J.E., and SIMONEAUX, B.J. (1988) Metolachlor. In: P.C. KEARNEY and D.D. KAUFMAN (eds), Herbicides: Chemistry, Degradation, and Mode of Action, New York: Marcel Dekker, pp. 335–382. LEVINE, I.N. (1995) Physical Chemistry, 4th edn, New York: McGraw Hill. MEININGHAUS, R., GUNNARSEN, L., and KNUDSEN, H.N. (2000) Diffusion and sorption of volatile organic compounds in building materials – impact on indoor air quality, Environmental Science and Technology, 34: 3101–3108. MEYLAN, W.M. and HOWARD, P.H. (1993) Computer estimation of the atmospheric gas-phase reaction rate of organic compounds with hydroxyl radicals and ozone, Chemosphere, 26: 2293–2299. MILLER, J.L., WOLLUM, A.G., and WEBER, J.B. (1997) Degradation of carbon-14-atrazine and carbon-14-metolachlor in soil from four depths, Journal of Environmental Quality, 26: 633–638. MORRISON, B., DRALLE, D., and DEMAREE, K. (1974) Effects of CS agents on vegetation: ii. field and screening studies, ECTR-74040, Edgewood Arsenal, Aberdeen Proving Ground, Maryland. NOMA, Y., AKEHI, E., MIKI, N., and ASAKAWA, Y. (1992) Biotransformation of terpene aldehydes, aromatic aldehydes, and related compounds by dunaliella tertiolocta, Phytochemistry, 31: 515–517. PARADOWSKI, M. (1979) Metabolism of Toxic Doses of o-Chlorobenzylidene Malononitrile (CS) in the Rabbits, Polish Journal of Pharmacology and Pharmacy, 31: 563–572. PATAI, S. and RAPPOPORT, Z. (1962) Nucleophilic attacks on carbon-carbon double bonds. Part II. cleavage of arylmethylene malononitriles by water in 95% ethanol, Journal of the Chemical Society, 383–391. PEARSON, J.G. (1975) The toxicity of the riot control agent CS (o-Chlorobenzylidene Malononitrile) and its hydrolysis products to the mumichog, fundulus heteroclitus (linnaeus), AD-A007 800, Defense Technical Information Center, U.S. Department of Defense. Defense Information Systems Agency, 8725 John F. Kingman Road, Suite 0944, Ft. Belvoir, VA 22060-6218. PHILIP, T. and FRANCIS, F.J. (1971) Oxidation of capsanthin, Journal of Food Science, 36: 96–97.


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PRAGER, J.C. (1995) Environmental contaminant reference data book, Vol. I, New York: Van Nostrand Reinhold, pp. 89–92. PUNTE, L.C., OWENS, E.J., GUNTENTAG, P.J. and ARSENAL, E. (1963) Exposures to orthorochlorobenzylidene malononitrile, Archives of Environmental Health, 6: 72. PURSEGLOVE, J.W., BROWN, E.G., GREEN, C.L., and ROBBINS, S.R.J. (1981) Spices, Longman Scientific and Technical, (Wiley) New York. SCHINDLER, A.F. and EISENBERG, W.V. (1968) Growth and production of aflatoxins by Aspergillus flavus on red pepper (Capsicum frutenscens L), Journal of the Association of Official Analytical Chemists, 51: 911–912. ROMANOV, V. and HAUSINGER, R.P. (1994) Pseudomonas aeruginosa 142 uses a three-component ortho-halobenzoate 1,2-dioxgenase for metabolism of 2,4-dichloro- and 2-chlorobenzoate, Journal of Bacteriology, 176: 3368–3374. SCHINDLER, A.F. and EISENBERG, W.V. (1968) Growth and production of aflatoxins by aspergillus flavus on red pepper (Capsicum frutenscens L), Journal of the Association of Official Analytical Chemists, 51: 911–912. SCHOTT, C.D. and WORTHLEY, E.G. (1973) Effects of CS and its breakdown products on the growth of duckweeds, AD-772 928, Edgewood Arsenal Technical Report EB-TR-73045, Department of Army, Aberdeen Proving Ground, Maryland. SCOTT, P.M. and KENNEDY, B.P.C. (1973) Analysis and survey of ground black, white, and capsicum peppers for aflatoxins, Journal of the Association of Official Analytical Chemists, 56: 1452–1457. SHARAK-GENTHER, B.R. (1999) Preliminary characterization of four 2-chlorobenzoate-degrading anaerobic bacterial consortia, Biodegradation, 10: 27–33. SHARP, D.B. (1988) Alachlor. In: P.C. KEARNEY and D.D. KAUFMAN (eds), Herbicides: Chemistry, Degradation, and Mode of Action, New York: Marcel Dekker, pp. 301–333. SMOLEN, J.M., WEBER, E.J., and TRATNYEK, P.G. (1999) Molecular probe techniques for the identification of reductants in sediments: evidence for reduction of 2-chloracetophenone by hydride transfer, Environmental Science and Technology, 33: 440–445. STAMPER, D.M., TRAINA, S.J., and TUOVINEN, O.H. (1997) Anaerobic transformation of alachlor, propachlor, and metolachlor with sulfide, Journal of Environmental Quality, 26: 488–494. THURMAN, E.M., GOOLSBY, D.A., AGA, D.S., POMES, M.L., and MEYER, M.T. (1996) Occurrence of alachlor and its sulfonated metabolite in rivers and reservoirs of the midwestern united states: the importance of sulfonation in the transport of chloroacetanilide herbicides, Environmental Science and Technology, 30: 569–574. TOPP, C., NIELSEN, P.V., and HEISELBERG, P. (2001) Influence of local airflow on the pollutant emissions from indoor building surfaces, Indoor Air, 11: 162–170. TOXNET (2001a) 2-Chloroacetophenone, http://toxnet.nlm.nih.gov/ . TOXNET (2001b) Chlorobenzalmalononitrile, http://toxnet.nlm.nih.gov . United States Environmental Protection Agency, (1992) Reregistration Eligibility Document (RED). Office of Prevention, Pesticides and Toxic Substances. VAN DER WOUDE, B.J., DE BOER, M., VAN DER PUT, N.M.J., VAN DER GELD, F.M., PRINS, R.A., and GOTTSHCAL, J.C. (1994) Anaerobic degradation of halogenated benzoic acids by photoheterotrophic bacteria, FEMS Microbiology Letters, 119: 199–208. VERSCHUEREN, K. (1983) Handbook of Environmental Data on Organic Chemicals, 2nd edn, Van Nostrand Reinhold Company, Inc. VUILLEUMIER, S. (2001) Bacterial glutathione-s-transferases and the detoxification of xenobiotics: dehalogenation through glutathione conjugation and beyond. In: J.C. HALL, R.E. HOAGLAND, and R.M. ZABLOTOWICZ (eds), Pesticide Biotransformation in Plants and Microorganisms, ACS Symposium Series 777, Washington, DC: American Chemical Society, pp. 240–252.



WON, D., CORSI, R.L., and RYNES, M. (2000) New indoor carpet as an adsoprtive reservoir for volatile organic compounds, Environmental Science and Technology, 34: 4193–4198. WON, D., CORSI, R.L., and RYNES, M. (2001) Sorptive interactions between VOCs and indoor materials, Indoor Air, 11: 246–256. WORTHLEY, E.G. and SCHOTT, C.D. (1971) The comparative effects of CS and various pollutants on fresh water phytoplankton colonies of wolffia papulifer, Thompson Edgewood Arsenal Technical Report 4595, Department of Army, Edgewood Arsenal, Maryland. YALKOWSKY, S.H., VALVANI, S.C., and MACKAY, D. (1983) Estimation of the aqueous solubility of some aromatic compounds, Residue Reviews, 85: 43–55. ZABLOTOWICZ, R.M., HOAGLAND, R.E., LOCKE, M.A., and HICKEY, W.J. (1995) Glutathione-s-transferase activity and metabolism of glutathione conjugates by rhizosphere bacteria, Applied and Environmental Microbiology, 61: 1054–1060.


CHAPTER

Genomics, Proteomics, and Computational Toxicology as Future Tools in Assessing Health Hazards of Riot Control Agents

17

AKBAR S. KHAN US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, MD 21010

17.1 INTRODUCTION Riot control agents (RCAs) represent highly potent sensory irritants with time-dependent acute site-specific toxicity. The clear genetic mechanism of their action is unclear but it is claimed that these chemicals interact pharmacologically with sensory nerve receptors associated with mucosal surfaces and the skin at the site of contamination, resulting in localized discomfort or pain with associated reflexes. The biological response, for example, ocular irritation, results in pain in the eye, which provides warning followed by excess reflex lacrimation and blepharospasm, which in turn provides protection. The kind of responses produced by these agents is concentration- and dose-dependent and therefore cease on removal of the sensory irritant stimulus. These kinds of compounds may also produce respiratory tract irritation and/or gastrointestinal irritation (i.e. nausea and vomiting). RCAs have both civil and military applications and have received classification as either military chemicals or chemical warfare agents. Common classifications are based on a predominant physiological action, although classification may also be based on use, physical state or persistency (Prentiss, 1937; Jacobs, 1942; Waitt, 1942; Sartori, 1943 – refer to Chapter 1 for a more in-depth discussion). Classifications, based on physical state or persistency are confusing, and therefore a revised classification system would better serve to classify these compounds. Use of genomics, proteomics, and computational toxicology would provide the basis for an improved classification scheme where the classification would be based on expression of families of genes affected by the exposure of these compounds (Figure 17.1). With the help of DNA microarray containing thousands of genes on a single platform, one will ultimately be able to build a library of the different biological pathways that are affected by these RCAs. Computational tools would be used to derive the structure–activity relationships using calculations to help determine the relationship between a chemical’s structure and its biological activity.


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Genomics Animal model

Riot control agents

Mammalian cell culture

Proteomics

Computer network containing signature of different riot control agents

Figure 17.1: Schematic illustration of genomics, proteomics and bioinformatics to

study RCAs.

Furthermore, these tools will help determine whether a compound that has not been tested for health effects may pose a risk because it contains a structure similar to a compound of known toxicity.

17.2 TOXICOLOGY OF RCAS RCAs are considered to have low toxicity, are potent sensory irritants that elicit acute sitespecific toxicity. In the literature, these agents are described as nonlethal (Olajos and Salem, 2001). Exposure to these agents may occur via inhalation, dermal, and oral routes of exposure. The primary target of these compounds is the eye, which is the most sensitive target organ; however, the majority of these compounds will also affect the pulmonary system if inhaled and the skin. RCAs can cause some or all of the effects on these target organs to a greater or lesser extent. Permanent adverse effects are usually not caused by RCAs; however, the deleterious effects by these agents increase with higher exposure levels and/or greater exposure times. The acute and in some instances the repeated-dose toxicity of RCAs have been studied reasonably adequately. In contrast, the extent of our knowledge concerning the long-term and chronic toxicity of these compounds is somewhat limited. Comprehensive studies should be initiated to investigate these compounds using genomic, proteomic and computational toxicology approaches, and methods to dissect out these compounds at a genetic level as depicted next. A database containing individual chemical studies into a knowledge-based science in which experimental data are compiled and computational as well as informatics tools will play a significant role in deriving a new understanding of chemical toxicity of different RCAs will be the focus of future studies on RCAs. The capacity to array large number of individual gene fragments on small matrices that can be hybridized to mRNA or cDNA has made it possible to synchronously access the variety of effects that specific chemical can cause, both good and bad. This new revolution in biology has led to the development of the field of toxicogenomics which proposes to apply both mRNA and protein expression technologies to study chemical effects in biological systems


GENOMICS, PROTEOMICS, AND COMPUTATIONAL TOXICOLOGY

(Afshari et al., 1999; Hamadeh and Afshari, 2000; Fielden and Zacharewski, 2001; Olden and Guthrie, 2001; Hamadeh et al., 2001; Hamadeh et al., in press; Lobenhofer et al., 2001). With the integration of genomics, proteomics, and bioinformatics, the effects of RCAs will be characterized to a progressively greater depth – especially the early genetic changes following exposure, that may give rise to long-term effects. In addition, studies that incorporate such cutting-edge technologies will enhance our understanding the biochemical and genetic complexity of the cellular processes of those biological systems that are adversely affected by these chemicals. Moreover, information and advances resulting from such studies have great potential in the development of safer riot control compounds as well as contributing to the design of novel pharmaceutical agents for the treatment of RCA-induced adverse effects.

REFERENCES AFSHARI, C.A., NUWAYSIR, E.F., and BARRETT, J.C. (1999) Application of complementary DNA microarray technology to carcinogen identification, toxicology, and drug safety evaluation, Cancer Research, 59: 4759–4760. FIELDEN, M.R. and ZACHAREWSKI, T.R. (2001) Challenges and limitations of gene expression profiling in mechanistic and predictive toxicology, Toxicological Sciences, 60: 6–10. HAMADEH, H. and AFSHARI, C.A. (2000) Gene chips and functional genomics, American Scientist, 88: 508–515. HAMADEH, H.K., BUSHEL, P., NUWAYSIR, E., PAULES, R., BARRETT, J.C., and AFSHARI, C.A. (in press) cDNA microarray technology: merging toxicology and genomics, Comments on Toxicology. HAMADEH, H.K., BUSHEL, P., PAULES, R., and AFSHARI, C.A. (2001) Discovery in toxicology: mediation by gene expression array technology, Journal of Biochemistry and Molecular Toxicology, 15: 231–242. JACOBS, M.B. (1942) War Gases, Their identification and Decontamination, New York: Interscience Publishers, p. 1042. LOBENHOFER, E., BUSHEL, P., AFSHARI, C.A., and HAMADEH, H.K. (2001) Progress in the application of DNA microarrays, Environmental Health Perspectives, 109: 881–891. OLAJOS, E.J. and SALEM, H. (2001) Riot control agents: Pharmacology, toxicology, biochemistry, and chemistry, Journal of Applied Toxicology, 21: 355–391. OLDEN, K. and GUTHRIE, J. (2001) Genomics: implications for toxicology, Mutation Research, 473: 3–10. PRENTISS, A.M. (1937) Chemical in War: A Treatise on Chemical Warfare, New York: McGraw-Hill Book Co. SARTORI, M. (1943) The War Gases, New York: D. Van Nostrand. WAITT, A.H. (1942) Gas Warfare, New York: Duell, Sloan, and Pearce.

DISCLAIMER NOTICE The opinions or assertions contained herein are those of the authors and are not to be construed as official or as reflecting the views of the Army or the Department of Defense.


CHAPTER

Issues/Concerns, Needs, Emerging Concepts/ Trends, and Advances in Riot Control Agents

18

WOODHALL STOPFORD1 AND EUGENE J. OLAJOS2 1 Division of Occupational and Environmental Medicine, Duke University Medical Center, Durham, North Carolina 2

US Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland

Earlier chapters of this book have focused on the application and use of riot control agents (RCAs), their chemistry and biochemistry, their pharmacological and toxicological effects in humans and animals, genotoxicity, and developmental/reproductive effects. Relevant and significant topics such as risk assessment/characterization, public health considerations, occupational health aspects, environmental issues, and aspects of forensic toxicology have been discussed and complement the discussions related to the biological actions of these compounds. It is critical to more fully understand the diverse biological actions of these compounds as well as to enhance our capability to develop safer and better RCAs. The development of safer RCAs requires the involvement of a broad array of scientific, technical, medical, and public health professionals. Moreover, it requires collaborative efforts with the law enforcement community, awareness of trends in the legal/policy arena, and cognizance of the growing public interest and concern in RCA use and health issues. In this chapter, we articulate the issues and concerns, the needs, emerging concepts/trends, and technological advances related to RCAs.

18.1 ISSUES AND CONCERNS Issues and concerns related to the use and safety of RCAs in crowd control and the use of these substances in self-defense sprays has increased considerably in recent years as evidenced in recent publications in the medical and scientific literature (Lee et al., 1996; Lewer and Schofield, 1997; Morabito and Doerner, 1997; Recer et al., 2001; Smith and Greaves, 2002). The heightened public concern that has been recently expressed was always and continues to be a matter of concern within the scientific, medical, and law enforcement communities (Pearlman, 1969; Sanford, 1976; Ballantyne, 1977; Danto, 1987; Hu et al., 1989; Hu, 1992; Smith and Stopford, 1999; Recer et al., 2001; Smith and Greaves, 2002). In 1972, the US Department of Justice in association with the National Science Foundation sponsored a National conference on research needs related to less than-lethal weapons – “coercive devices and agents that could subdue without creating


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substantial risk of personal injury or death.” Subsequently, the National Institute of Justice of the US. Department of Justice convened a conference to assess the current state of law enforcement use/application of less-than-lethal devices, to evaluate recent advances in technology, as well as to explore issues that would be of concern and relevance in the future development of less-than-lethal technologies. The proceedings of this conference was published in a National Institute of Justice report (Sweetman, 1987). Many of the issues and concerns expressed at the NIJ conference are still relevant to current policing technology and operations and other issues have since surfaced, particularly as related to fundamental changes, that are taking place in the types of techniques and technologies available for policing purposes. Questions related to the use of lessthan-lethal devices, including chemically-based devices, used by law enforcement and in peace-keeping operations remain unanswered, unconsidered, or under-researched. The issues and concerns related to RCAs are many and varied, ranging from operational aspects to health and legal issues and concerns. The issues and concerns may be considered from broad perspectives such as: (1) the use of science and technology in the development of less-than-lethal weaponry/devices, (2) health risks and environmental concerns associated with the use of RCAs, (3) public perception related to the use of RCAs, (4) contemporary and future policing techniques, and (5) legal/policy aspects. Within this context, one must recognize two critical aspects related to RCA use. First, that RCAs represent one spectrum of less-than-lethal force used by law enforcement in the handling of non-compliant or combative individuals and by those involved in crowd control and peace-keeping operations. The second aspect is that of providing law enforcement with a RCA having optimal efficacy and safety, which is rooted in the concept or notion of an “ideal” or “perfect” RCA. Moreover, the use of RCAs in policing situations and in civil disturbances must be seen in the context of alternatives, which include firearms, electrical devices, batons, police dogs, etc. Thus, other less-than-lethal technologies are also available to law enforcement personnel and are used depending on the situtation and circumstances. Compared with the option of using lethal force, to prevent the injury or death of a police officer(s) or victim(s), RCAs must be seen as the better alternative. Furthermore, it is important not only to revisit the application of these materials in contemporary policing procedures and techniques for riot control, but is also equally important to keep abreast of developments in policing technology. Fundamental changes are and will take place in the type of technologies available for law enforcement (policing) purposes and modern riot control technologies. The second critical aspect that must be considered relates to the concept of an “ideal” RCA. Optimally, a “police-type irritant” or RCA should be characterized by a combination of biological and physical properties that will ensure that lethal consequences will be rare and that “harassing” effects will be transient and relatively mild. The development of an “ideal” or “perfect” RCA may not be attainable, yet development efforts should be directed towards producing an RCA that is an effective option for control of an assailant or effective in civil disobedience situations without causing harmful effects, persistent injury, or death. Because of their higher degree of safety and the uncertain efficacy of chloroacetophenone (CN), the RCAs oleoresin capsicum (OC) and chlorobenzylidene malononitrite (CS) have largely replaced CN for riot control use. Oleoresin capsicum (pepper spray) in particular has gained widespread acceptance with law enforcement agencies. For modern RCAs such as CS and OC, a large margin exists between the dosage that elicits peripheral sensory irritation and that which produces adverse health (unintended) effects. Thus, when assessing the safety profile of CS or OC, it is essential to note that “…in many instances… (there use may…) reduce injuries to officers as well as arrestees…” (Smith and Stopford, 1999). Yet, despite its high degree of safety and effectiveness, concerns have recently surfaced regarding the overall efficacy of OC sprays. Indications are that OC spray may not be as effective on highly agitated individuals or those in an aggressive state induced by drugs or alcohol as


ISSUES, NEEDS, EMERGING TRENDS, AND ADVANCES

originally claimed. However, it is important to note that a large body of data supports the position that OC sprays have a much greater degree of effectiveness on agitated individuals than either CN or CS. Despite the high degree of safety associated with OC use, concerns have focused on the deaths resulting from law enforcement use of OC spray and has become an issue of great concern for law enforcement agencies and pepper spray manufacturers. Regarding the safety of RCAs, the key point is that despite the low toxicity of modern RCAs, these compounds are not entirely without risk, particularly if one takes into account conditions of prolonged exposure, very high concentrations, and susceptible subpopulations (asthmatics, the very old, the very young). The risk of toxicity is elevated under conditions of high exposure concentrations and/or excessive exposure durations and also with the use of over-age formulations. Unintended effects involving the eyes, respiratory system, and skin can occur under the aforementioned conditions, particularly on exposure to CN and even with CS, which is deemed safer than CN. Furthermore, it is best recognized that exposure to RCAs in enclosed spaces may produce adverse health effects irrespective of the RCA that is utilized to quell a disturbance. Moreover, it should also be noted that the misuse or the over-zealous use of an RCA may result in varying degrees of eye, lung, and/or skin damage. This leads to issues and concerns related to the training of law enforcement and other personnel in the proper use of RCAs – unfortunately there are no clear-cut guidelines concerning the use of or the type of RCA. Operationally, many law enforcement agencies have adopted and implemented a “use of force matrix” which defines various levels of “force” and their appropriate application depending on the condition or situation of a policing action. Training must be provided to ensure that those authorized to use RCAs and devices do so safely, and policies and procedures to govern their appropriate use must be implemented and developed. The degree and quality of research that supports the development of RCAs are of great concern. Some would argue that the collective database on some RCAs is rather extensive – it has been stated that for certain RCAs; for example, CS “as much is known of the toxicity of CS as for many regulated chemicals such as pesticides.” The database for other RCAs (i.e. oleoresin capsicum); however, is not as complete. There is no question that many areas related to the health aspects as well as the application/use of RCAs are underresearched. Concerns have been expressed regarding the inadequate testing of RCAs as pertaining to formulations, long-term health effects, and effects on susceptible subpopulations. An additional concern of considerable magnitude is the research used to justify the introduction of new technologies (innovations) in law enforcement practices and riot control. Regarding the adequacy of testing and the health and safety aspects of currently utilized or novel RCAs, the following questions should be asked: ● ● ●

● ●

Has adequate biological testing been performed to evaluate the genotoxic potential? Has adequate biological testing been performed to evaluate efficacy of material? Has adequate biological testing been performed to evaluate the physiological and toxicological target organ effects (e.g. eye damage, inhalation toxicity, skin injury, allergic response, hypersensitivity, etc.) by various routes of exposure? Has adequate biological testing been performed to evaluate long-term effects? Has adequate biological testing been performed to evaluate effects in susceptible subpopulations?

18.2 NEEDS Collectively, there are a number of needs related to RCAs ranging from research to risk assessment/characterization/management and regulatory initiatives. Clearly, there is


RIOT CONTROL AGENTS

a great need to conduct rigorous studies and to validate claims by manufacturers as to the efficacy and safety of their products. Rigorous studies similar to those utilized by the pharmaceutical industry for new drug development and approval needs to be done. As to the safety and effectiveness of products currently on the market, it is critical that independent studies need to be conducted in order to validate the claims of manufacturers as to the efficacy and health aspects associated with their products. Likewise, there is a considerable and urgent need for additional research (in particular via inhalation) to define and delineate the biological and toxicological actions of OC as well as that of other RCAs and to illuminate the full health consequences of these compounds. A greater effort is needed to determine ingredients, potency, dose characteristics, and dose-related effects on the biological organism. Overall, the health community needs to understand that chemicals can cause both classically recognized chemically-induced illness (i.e. solvent intoxication, allergic reaction to chemicals) and less understood , but none-the-less real, health effects associated with low-level exposures and episodic exposures to chemicals – as in the case of RCAs. Inhalation-based pharmacodynamic/pharmacokinetic studies should be conducted on RCAs For example, the absorption characteristics of capsaicin/capsaicinoids via a critical uptake route such as inhalation has not been elucidated and should be done. Studies in suitable animal models should be conducted to address the issues/concerns related to the effects of RCAs on susceptible subpopulations. Moreover, some of the data (depending on one’s point-of-view) are outdated and stateof-the-art research should be conducted on all RCAs to include chloroacetophenone. In addition to needs related to the research and development of RCAs, there are critical needs in the following areas: (1) risk assessment and characterization, (2) training in the use and application of RCAs, and (3) regulatory initiatives and guidelines governing their use and application.

18.3 EMERGING CONCEPTS/TRENDS AND ADVANCES One can reflect on recent developments in RCAs and relate them to the development of less-than-lethal technologies,1 emerging concepts and trends within the law enforcement community, and legal/policy issues related to policing and law enforcement actions. The police are one of the few social institutions empowered to apply physical force to coerce individuals into compliance; however, as Fyfe (1988) has indicated, the laws governing police use of force tend to be vague. This lack of preciseness or equivocation exposes the police to an increased risk of civil liability, which has been addressed by various law enforcement agencies. Law enforcement agencies have developed guidelines or a “use-offorce” matrix. The use-of-force matrix spell out rules of engagement when law enforcement personnel are confronted with a non-compliant or combative individual(s). Within this framework, a broad range of less-than-lethal technologies (e.g. chemical, impact devices, electrical devices, and distraction/disorientation devices) may be employed to include the use of RCAs. The objective is to provide the police with options to allow a use-of-force commensurate with the threat being faced. RCAs enable police to have greater coercion.

18.3.1 Advances In general, devices (weapons) currently used by law enforcement include chemical devices, electrical devices, and impact devices. Technological innovations have taken place in policing techniques and modern riot technology, which includes chemically



based devices. Despite extensive research, four compounds have been developed for use in self-defense sprays and for riot control (civil disturbance) situations. As stated, past technology in the development of RCAs has focused primarily on the peripheral sensory irritants, and the few advances in this arena have been confined to the development of self-defense sprays. The major advance relates to the use of “synthetic” capsaicin (nonivamide) as the active ingredient in self-defense sprays – as opposed to oleoresin capsicum. It is claimed that the use of nonivamide provides a safer as well as a more consistently effective agent than the use of OC in self-defense spray formulations. Nonivamide appears to have the following potential advantages over OC: single compound, reproducible pungency and quality, and is not subject to variations in strength and effectiveness, which occur in OC products. It is recognized that OC is a highly variable and complex mixture of ingredients and is not a quantifiable chemical product that complies to any form of consistent measurement or specification. Being a simple, identifiable chemical, synthetic capsaicin (nonivamide) can be tightly specified under chemical assay and comply with a given standard. Also, in the area of active ingredients, some consideration has been given to the use of malodorants (olfactory compounds) for use as an RCA. Other technological improvements, that have led to safer self-defense spray products, include the use of solvents/carriers having fewer health and environmental risks. Also, technologies related to self-defense sprays have included the mixing or blends of RCAs (e.g. OC/CS; OC/CN) – Mixing of RCAs may make for a “stronger” product but use of such formulations adds significantly to adverse effects or unintended effects.

18.3.2 Recommendations Having identified concerns, issues, and needs, we turn to specific recommendations. They are as follows: a

b c d e f

g

h

i j

Before any of the less-than-lethal technologies are used, it is strongly recommended that they are subject to a full and rigorous evaluation, including health and medical aspects. Rigorous testing/research and controlled studies should be performed. Identify key areas of research/research needs (e.g. formulations testing, studies to address susceptible subpopulations, use of appropriate animal models). Integrate state-of-the art and emerging technologies (e.g. animal models, proteomics/genomics) to better assess the health hazards of RCAs. Match the needs of law enforcement community with current and emerging technologies. Validate claims of manufacturers. Agencies that introduce new tactics or techniques should closely monitor their implementation. Such an approach can determine the effectiveness of a new product and protect against/minimize unintended consequences. In situations involving individuals, forensic and medical experts should be involved in order to assess the appropriateness of actions taken in policing actions involving RCAs. Moreover, medical evaluation should be sought in an effort to evaluate the individual clinically and such observations can provide a foundation for guidelines. To guide the development of initiatives – relevant to the issues, concerns, and problems associated with the use of RCAs – promote interaction among federal agencies such as NIJ, NIOSH, NIH, NIST, and EPA and establish interagency working groups at the federal and state levels. Conduct risk assessment/characterization and perform effective risk communication. Develop protocols/procedures for controlling and regulating product availability.


RIOT CONTROL AGENTS

k

l m n

Training must be provided to ensure that those authorized to use such devices do so safely, and policies and procedures to govern the appropriate use must be developed. (Encourage) cooperation is required among scientists, law enforcement officials and manufacturers in the development of safe and effective RCAs. Implementation of some form of regulation (i.e. state and or local level). Resolution of conflicts between the RCA manufacturers, the public and advocacy groups. One approach is the establishment of interagency working groups and the involvment of the health/medical community. Establishment of an independent panel of health and science professionals.

18.4 CONCLUSIONS There may never be a “perfect” RCA or personal protective device – one that is immediately effective and not associated with adverse health effects, long-term risks to either user or victim. The optimal RCA used in crowd control or as a self-defense spray is one having a high degree of safety, a rapid onset of action, a sufficient degree of effectiveness, a short duration of action, and no long-term sequelae. RCAs, in particular OC and CS, appear to provide an effective less-than-lethal option to terminate inappropriate/hostile behavior with minimal unintended effects. The unintended effects that could occur with the use of RCAs should be viewed in the context of the use of lethal force and of the consequences of not achieving control of an assailant or non-compliant individual.

NOTES 1. Less-than-lethal is a term used to define devices, weapons, equipment to include RCAs and other chemicals (i.e. olfactory agents) that although less likely than firearms to result in a serious or fatal injury, nevertheless carry some degree of risks.

REFERENCES BALLANTYNE, B. (1977) Riot control agents, biomedical and health aspects of the use of chemicals in civil disturbances, in Medical Annual, R.B. SCOTT and J. FRAZER, (eds) , Bristol: John Wright, pp. 7–41. DANTO, B.L. (1977) Medical problems and criteria regarding the use of tear gas by police, The American Journal of Forensic Medicine and Pathology, 8: 317–322. FYFE, J.J. (1988) Police use of deadly force: research and reform, Justice Quarterly, 5: 165–205. HU, H. (1992) Toxicodynamics of riot-control agents (lacrimators). In: S.M. SOMANI, (ed.), Chemcial Warfare Agents, New York: Academic Press, pp. 271–288. HU, H., FINE, J., EPSTEIN, F. et al. (1989) Tear gas: harassing agent or toxic chemical weapon?, Journal of the American Medical Association, 262: 660–663. LEE, R.J., YOLTON, R.L., YOLTON,D.P., SCHNIDER, C., and JANIN, M.L. (1996) Personal defense sprays: effects and management of exposure, Journal of the American Optometric Association, 67: 548–559. LEWER, N. and SCHOFIELD, S. (1997) Non-lethal Weapons: A Fatal Attraction?, London, Zed Books. MORABITO, E.V. and DOERNER, W.G. (1997) Police use of less-than-lethal force: oleoresin capsicum (OC) spray, Policing: an International Journal of Police Strategy and Management, 20: 680–697. PEARLMAN, A.L. (1969) Non-lethal weapons for use by law enforcement agencies, New Physician, August: 625–628.



RECER, G.M., JOHNSON, T.B. and GLEASON, A.K. (2002) An evaluation of the relative potential health concern for the self-defense spray active ingredients oleoresin capsicum, o-chlorobenzylidene malononitrile, and 2-chloroacetophenone, Regulatory Toxicology and Pharmacology, 36: 1–11. SANFORD, J.P. (1976) Medical aspects of riot control (harassing) agents, Annual Review of Medicine, 27: 412–429. SMITH, J. and GREAVES, I. (2002) The use of chemical incapacitant sprays: a review, The Journal of Trauma, 52: 595–600. SMITH, C.G. and STOPFORD, W. (1999) Health hazards of pepper-spray, North Carolina Medical Journal, 60: 268–274. SWEETMAN, S. (1987) Report on the Attorney General’s Conference on Less-Than-Lethal Weapons, (March, 1987), Issues and Practices in Criminal Justice, National Institue of Justice, U.S. Department of Justice, Washington, DC.



APPENDIX

Definitions and Terminology

A

Aflatoxins Toxins produced by various fungi species that cause acute and chronic liver damage and risk of liver cancer. Airway reactivity Increased “twitchiness” of airways such that bronchoconstriction is more likely to occur with nonspecific stimuli such as hyperventilation (rapid breathing), exercise, breathing in cold or dry air or when exposed to irritants. Increases occur temporarily (for days or weeks) after viral bronchitis, exposure to ozone (air pollution) or irritants. Permanent increases in airway reactivity are seen in asthma, chronic bronchitis and reactive airways dysfunction syndrome. Commonly quantified with a methacholine challenge. Alkylation Substitution of an aliphatic hydrocarbon radical for a hydrogen atom in a ring compound. Allergic hypersensitivity Hypersensitivity to a specific substance (antigen) that results in an antigen–antibody reaction manifested by such disorders as asthma, allergic rhinitis, contact dermatitis, and hives. Alveolitis Inflammation of the air cells in the lungs. Atelectasis Collapse of a portion of the lung, usually due to a blocked airway. Anatomy Cerebellum Back part of brain, involved in coordinated movements. Cornea Clear part of the eye in front of the lens. Larynx Voice box. Mitral valve Heart valve between the left atrium (chamber receiving blood from the lungs) and left ventricle (chamber that pumps blood to the body). Pharynx Throat (pharyngeal: related to the throat). Sural nerve Sensory nerve extending from mid-calf to back of the foot. Blepharospasm Spasmodic winking. Blood tests Liver function studies Alkaline phosphatase; Serum glutamic oxaloacetic transaminase (SGOT); Bilirubin; Gamma glutamyl transpeptidase (GGTP); Lactic dehydrogenase (LDH). Kidney function studies Blood urea nitrogen (BUN); Creatinine. Serum electrolytes Potassium, Sodium, Chloride. White blood cells Monocytes, Lympocytes, Neutrophils, Eosinophils, Basophils. Bronchoconstriction Spasmodic narrowing of the larger airways (bronchi).


RIOT CONTROL AGENTS

Bronchiolitis Inflammation of the smaller airways, between the bronchi and alveoli (bronchioles). Bronchitis Inflammation of the larger airways (bronchi). Bullous dermatitis Widespread blisters and redness. Burns First degree Redness. Second degree Blistering; heal without scars. Third degree Full thickness burns; heal with scars. Bronchopneumonia Combination inflammation of the smaller airways, usually with some obstruction and lung collapse (atelectasis) together with filling of air cells (alveoli) with fluid. Can be a result of either infection or inflammation, such as from an irritant gas. Collagenase An enzyme released when there is tissue damage that results in further damage to collagen. Conjunctivitis Inflammation of the membrane covering the front part of the eyeball (conjunctiva or white part of the eye). Contact dermatitis Redness, swelling and/or blistering of the skin secondary to a reaction from contact to a substance to which an individual is allergic or hypersensitive. Cyanotic Turning blue from lack of oxygen or poor circulation. Debridement Intentional removal of dead tissue or skin to promote healing and prevent infection. Desquamation Shedding of the outer layer of skin (epidermis). Diabetic neuropathy Damage to nerves, particularly those of the hands and feet, that is seen in individuals with diabetes for a number of years. This neuropathy is often associated with funny feelings (dysesthesias) or pain in the affected areas. Draize patch test procedure Placing a substance on the skin under an occlusive (air tight) dressing. For irritation testing, the patch is usually left in place for 24 h. For allergy testing, the patch can be left in place for 48–72 h. with repeated (insult) patch testing at the same location for 2–3 weeks. After a rest of two weeks, the individual receives a challenge patch test with a concentration of the chemical that will not cause irritation but at a different location. Dysesthesias Damage to sensory nerves resulting in a disagreeable sensation to ordinary stimuli, such as touching. Ecchymoses A purplish patch from bleeding into the skin. Epistaxis Bleeding from the nose, usually related to infection or inflammation with damage to the epithelial lining of the nose. Eschar A scab caused by a burn. Emphysematous changes Enlargement of air cells due to loss of membranes separating adjacent cells. Enteroscopy Visualization of the gastrointestinal track by passing either a hollow tube or fiber-optic unit through the mouth (to visualize the stomach and upper intestine) or anus (to visualize the colon). Epithelial defects Small areas of swelling of the epithelial cells of the cornea that show up as bright spots when the cornea is stained with fluorescein dye. They represent early, reversible damage to the corneal epithelium. Ergometer A machine, such as treadmill or bicycle, that measures work efficiency. Used for cardiac and pulmonary stress tests. Extracorporeal membrane oxygenation (ECMO) An artificial lung. Fibrotic Leathery from laying down scar tissue usually secondary to either an attempt to repair damage or from reaction to inflammation. Fluorescein staining Staining of the cornea with a dye that will remain in abraded or damaged areas and fluoresce or glow under a Woods (UV) light.


DEFINITIONS AND TERMINOLOGY


Gavage Introducing material into the stomach with a tube. Usually done as a single dose each day. Glucocorticosteroids Derivatives of the steroid hormones produced by the adrenal glands, such as cortisol or prednisone. Used to treat skin and tissue inflammation or allergic reactions. Histamine Chemical released into tissues as part of the allergic response resulting in redness, swelling, and itching. It is involved in causing an asthmatic attach (bronchoconstriction) after inhalation of a substance to which a person is allergic. Hyperinflation Enlargement of air cells in the lungs either due to air trapping from bronchoconstriction or from emphysematous changes, with damage to the walls of air cells. Hypoxemia Low blood oxygen levels. Inflammatory hyperpigmentation Darkening of the skin, such as with a sun tan, seen after second degree burns. Intraocular pressures Pressure inside the eyeball. A certain amount of pressure is necessary to maintain the eye’s shape. With elevated pressures (glaucoma) there can be damage to the eye with loss of vision. Iritis Inflammation of the iris or pupil. Individuals with iritis are light sensitive with pain when in bright light where the iris contracts with the pupil getting smaller. Keratitis Inflammation of the cornea. This is often associated with pain with blinking or a sensation as if something is in the eye. Keratinization Changing of tissues to skin-like with a horny layer of cells. Lavage Washing out the nose or airways with a saline solution. Leukotriene inhibitors Leukotrienes are released from various cells, including mast cells, basophils, and eosinophils, and play a roll in asthma. Their release results in the airway swelling, bronchoconstriction, increased levels of inflammation, increased levels of eosinophils in tissues, and airway reactivity. Inhibitors are medicines that prevent them from acting. Mast cells Tissue-based allergy cells. Can release leukotrienes with nonspecific stimulation (such as irritant exposure) or when sensitized to an antigen. Eosinophils and basophils are circulating cells with similar functions. Morbilliform eruption Resembling measles (many spots). Mucosal epithelium Lining of the airways in the chest and nose where mucous is produced. Necrotizing Causing tissue death. Nerve conduction Testing how rapidly an impulse travels along a nerve, measured from the time a stimulus is made until the stimulus can be measured a known distance along the nerve. Stimuli can be electrical to muscles or nerves or from stimulation of sensations. Neurogenic extravasation Loss of fluids into tissues as a result of release of an inflammatory substance, substance P. Occlusive dressing Air tight dressing. Optic nerve atropy Loss of fibers in the optic nerve usually secondary to build up of pressure in the eyeball (glaucoma) or direct damage to the nerve. Optic atropy is associated with loss of vision. Palpebral Relating to the eyelid. Paresthesias An abnormal spontaneous sensation such as burning, prickling, or numbness. Pathology terms Anisocytosis of hepatocytes Variation in the size of liver cells. Coagulative necrosis Severe necrosis to the point of loss of cell walls. Dorsal root ganglion cells Collection of sensory nerve cells as the nerve leaves the spinal cord.

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Histopathology Microscopic study of tissues. Hydropic degeneration of basal cell layer Swelling of cells of the deepest layer of the skin or dermis to the point of bursting. Hyperplasia Increase in the numbers of cells of a tissue. Intra-alveolar hemorrhage Bleeding into air cells of the lungs. Peribronchiolar and perivascular lymphoid tissue Tissue that collect and transports clear body fluid (lymph) found surrounding bronchi and blood vessels. Periosteum Covering of the bone from which bone is made. Squamous metaplasia Change of mucosal epithelial cells to having a skin-like character. Spongiosis of the prickle cell layer Cellular edema of the epidermis of the skin. Stratum corneum The outer layer of the skin consisting of dead cells. Postherpetic neuralgia Severe pain in the nerve distribution of nerves chronically infected with the herpes virus. Prophylactic Preventative. Pseudomembranes Lining of the upper airways made up of mucous and dead cells resulting from severe damage to the epithelial lining. Pulmonary edema Swelling of the tissues of the lungs either secondary to lung inflammation and damage or because of a build up of lung fluid from heart failure. Pulmonary function studies Alveolar volume The portion of the volume of the air in lungs that is found in the alveoli or air cells. Total lung volume includes the alveolar volume and the volume of the airways. Carbon monoxide diffusion test A test that measures the ability of gases to exchange between the blood and air cells of the lungs. Forced expiratory volume in 1 second (FEV1) The amount of air a person can blow out in one second. Forced vital capacity (FVC) The most air a person can blow out when fully emptying his or her lungs. Methacholine challenge FEV1 is measured after breathing in a specific amount of methacholine (a derivative of the nerve transmitter, acetylcholine) in increasing amounts. Individuals with asthma or RADS have increased sensitivity to methacholine. Tidal volume The volume of air that is breathed out with each breath at rest. Purpura Purplish discoloration from bleeding into skin (ecchymoses). Reactive airways dysfunction syndrome (RADS) Development of chronic inflammation of the airways with an asthma tendency after an acute chemical irritation to the airways. To fit the definition of RADS an individual should not have a history of prior asthma or chronic bronchitis. Individuals with RADS get bronchospasm when exposed to irritants, cold or dry air, or when exercising. Their condition lasts for years or may be permanent. A methacholine challenge test is positive. Symptoms associated with RADS include a dry cough, shortness of breath, wheezing, and a burning chest pain when breathing in. Sensory hyperreactivity (SHR) Asthma-like symptoms after exposure to nonspecific irritating stimuli, but without IgE-mediated allergy, demonstrable bronchial obstruction, or airway reactivity. Slit lamp biomicroscopy Evaluating the clear portions of the eyes under a microscope. Somatostatin A nerve-associated protein found in various tissues including the skin that modulates hormone release, heart action, and blood vessel tone. Standardized mortality ratio (SMR) The ratio of number of deaths in a population over the number that are expected 100. A normal SMR is 100. Subcutaneous edema Swelling in the tissues under the skin. Submaximal exercise testing Exercising on a treadmill or bicycle until the heart rate is 85% of that that is predicted for a person’s age.


DEFINITIONS AND TERMINOLOGY


333

Substance P A substance that collects in the end of sensory nerve roots that is released when there is local inflammation. Release is associated with redness, pain, and inflammation. Suppurative Forming pus. Systemic Administration of a drug into the body by vein, in muscle, or through skin. Tendon sheaths Fibrous covering of tendons. Tendonitis is the inflammation of these sheaths. Tonsillar herniation Swelling of the brain with protrusion of the base of the brain into the opening of the skull to the spinal cord. This usually results in death. Tracheitis Inflammation of the portion of the airways between the larynx and bronchi (trachea). Tracheobronchitis Inflammation extending from the trachea to the bronchi. Uriticaria Hives or wheals forming on the skin usually secondary to an allergic reaction from direct contact to a material or indirect contact such as from eating or breathing a substance. Units dL deciliter: 1/100th of a Liter. kg kilogram: 1000 g. mg milligram: 1/1000th of gram. mol mole: One mole is the molecular weight of a substance in grams. ng nanogram: 1 billionth of a gram. pg pictogram: 1 trillionth of a gram. g microgram: 1 millionth of a gram. m micrometer or micron: 1 millionth of a meter. mg-min/m3 measure of dose: milligrams x exposure time (in minutes)/cubic meter. M Molar: moles per liter. mM millimolar: 1/1000th molar. M micromolar: 1 millionth molar. Vascularization Growth of new blood vessels. Occurs after damage to the cornea with loss of the epithelium (outer cell cover). Vasoactive intestinal polypeptide A nerve transmitter found in skin and lung tissue that causes constriction of blood vessels. Vesicle Small blister. Vesicular rash Dermatitis where the skin is red and covered with small blisters. Vesiculation Forming blisters.

APPENDIX

Decontamination and Medical Management after Exposures to Riot Control Agents

B

B.1 DECONTAMINATION Although riot control agents (RCAs) are used primarily because they can cause incapacitation without injury, there is a risk of persistent skin and eye effects with heavy exposures or when exposure occurs to those who are sensitive to an RCA. Effective decontamination can relieve irritation symptoms and decrease risk of eye or skin injury or delayed effects, such as a contact dermatitis (Penneys et al., 1969; Thorburn, 1982). The basic approach to decontamination appears to be useful for all RCA exposures is as follows. ●

●

●

●

Remove contaminated clothing, placing it in a plastic bag until the clothing can be laundered. The continued wearing of contaminated clothing will increase skin contact to RCAs and risk of adverse effects. Decontaminate skin with either soap or detergent and water. This approach provides immediate relief with RCA exposures where washing with water alone is ineffective. A mildly alkaline soap or detergent solution will both remove the RCA and, in the case of o-chlorobenzylidene malanonitrile (CS), result in rapid hydrolysis of the agent to a less toxic form (Weigand, 1969). Remove all cosmetics and contact lenses during the decontamination process. RCAs can be trapped in lipid cosmetics and soft contacts resulting in continued exposures (Lee et al., 1996; Atkins, 2003). If there are eye symptoms that persist for more than 10 min, flush eyes with 1–2 L of normal saline or a lactated Ringer’s solution over 15 min. A few drops of an anesthetic, such as 0.5% proparacaine, can relieve blepharospasm and facilitate irritation (Stopford and Bunn, 1989; Claman and Patterson, 1995).

At least one proprietary decontaminating agent is available that appears to be effective for decontaminating skin when access to soap and water is not immediately available. It has been used for the immediate treatment of oleoresin capsicum (OC) spray exposures but is said by its manufacturers to be effective for decontaminating skin exposed to CS and 1-chloroeoacetophenone (CN) as well (Giardino, 1997). When exposure occurs indoors, increased ventilation (such as with window fans) will help remove RCAs. An alkaline detergent solution can effectively remove RCAs from impervious solutions and destroy residual CS. Sodium hypochlorite should not be used as a decontaminate for CS-exposed surfaces: it reacts with CS to produce a more toxic chemical (Gutentag et al., 1960).


RIOT CONTROL AGENTS

Those who are involved in decontaminating either affected individuals or areas should wear appropriate personal protection to prevent inadvertent secondary exposures. Such exposures can occur from touching contaminated skin or clothing or when particles are re-entrained when entering an enclosed area. At a minimum impermeable gloves should be worn and the hands washed after removing the gloves to remove any residual chemical. For work in enclosed areas where there may be airborne exposures, a NIOSH-approved full-face respirator equipped with an organic vapor cartridge and high efficiency particulate filter and can prevent respiratory and eye symptoms (Weigand, 1969).

B.2 MEDICAL MANAGEMENT B.2.1 Eye contact Exposure to RCAs can result in corneal epithelial damage and, from rubbing the eyes, corneal abrasions. Consequently, if eye symptoms last more than an hour, an ophthalmologic examination with a slit lamp evaluation of the cornea supplemented by fluoroscein staining is indicated. Small epithelial defects are common findings and usually resolve within 24 h without treatment (Brown et al., 2000). With damage to the cornea to the point of epithelial loss there can be release of collagenase which can result in further corneal damage after a delay of 1–3 weeks. Glucocorticosteroid drops have proved ineffective in relieving eye irritation symptoms and may inhibit regeneration of corneal collagen. If there is epithelial loss or if glucocorticosteroid drops need to be used because of persistent eye inflammation, then anticollagenase drops should be used. These include 10% Mucomyst, 0.25 M 1-cystine and 0.2 M calcium EDTA (Stopford and Bunn, 1989; Lee et al., 1996).

B.2.2 Skin contact Persistent or high level contact to some RCAs can lead to a primary contact dermatitis, presenting as a chemical burn. Treatment is as that for a chemical burn. Redness alone does not require treatment. With vesicular rashes or blistering, denuded areas should be treated with a topical antibiotic to prevent secondary infections. With extensive or large bullae, debridement, and applications of a silver sulfadiazine solution, as with any second or third degree burn, are appropriate. Topical glucocorticosteroid creams are useful for treating the persistent induration that can be seen with CN and CS exposures and, in severe cases, oral prednisone may be necessary (Bowers et al., 1960; Hellreich et al., 1967; Thorburn, 1982). Individuals with single or repeated exposures to CN or CS can develop an allergic contact dermatitis as well. Topical glucocorticosteroids are usually effective in treating allergic vesicular rashes associated with contact to these agents. Treatment may have to extend for weeks (Sanford, 1976; Leenutaphong and Goerz, 1989).

B.2.3 Inhalation exposure Inhalation of RCAs can result in airway irritation and, with heavy exposures, lung damage and pulmonary edema, or even respiratory failure. A number of therapies have been evaluated under controlled conditions and have proven ineffective at preventing airway irritation-related effects. These include prophylactic antibiotics and atropine (Gutentag et al., 1960; Punte et al., 1962).


MEDICAL MANAGEMENT AFTER EXPOSURES TO RCA

Any airway irritant will cause bronchospasm at high level exposures and such a problem can be persistent for hours. Systemic or inhaled bronchodilators are effective for ameliorating irritant-induced bronchospasm. If an inhaled bronchodilator is not immediately effective, then systemic aminophylline followed by systemic glucocorticosteroids should be considered (Punte et al., 1962; Stopford and Bunn, 1989). Systemic glucocorticosteroids may be useful in the management of pulmonary edema associated with high level RCA exposures. With respiratory failure, treatment with high pressure ventilation and high oxygen tensions can lead to irreversible lung damage. The use of extracorporeal membrane oxygenation has been used successfully in treating RCA-related lung damage without evidence of long term lung effects (Winograd, 1977; Billmire et al., 1996) Individuals with airway inflammation from exposure to RCAs may develop reactive airways dysfunction syndrome (RADS) where there is nonspecific airway reactivity with bronchospasm occurring with exposure to irritants and cold or dry cold air or when exercising. A treatment regime that is effective for controlling the nonspecific airway reactivity associated with asthma is likely to be effective for treating RADS as well. Such a program may include inhaled long-acting bronchodilators, glucocorticosteroids, ipratropium bromide (an anticholinergic agent) and cromoyln sodium. Oral leukotriene inhibitors are also useful.

REFERENCES ATKINS, J.M. (2003) Advanced chemical weapons. Everything you ever wanted to know about Chemical Weapons … But didn’t know who, what, or where to ask. http://www.tscm.com/ mace.html BILLMIRE, D.F., VINOCUR, C., GINDA, M., ROBINSON, N.B., PANITCH, H., FRISS, H., RUBENSTEIN, D., and WILEY, J.F. Pepper-spray-induced respiratory failure treated with extracorporeal membrane oxygenation, Pediatrics, 98(5): 961–963. Bowers, M.B., Owens, E.J., and Punte, C.L. (1960) Interim report of CS exposures in plant workers. CWL Technical Memorandum 24–50, Army Chemical Center, MD. BROWN, L., TAKEUCHI, D., and CHALLONER, K. (2000) Corneal abrasions associated with pepper spray exposure, Am. J. Emerg. Med., 18(3): 271–227. CLAMAN, F.L. and PATTERSON, D.L. (1995) Personal aerosol protection devices: caring for victims of exposure, Nurse Pract., 20(11 Pt 1): 52–56. GIARDINO, B.A. (1997) Pepper spray antidote successful in one emergency department, J. Emerg. Nurs., 23(2): 96. GUTENTAG, P.L., HART, J., OWENS, E.J., and PUNTE, C.L. (1960) The evaluation of CS aerosols as a riot control agent in man. US Army Chemical Warfare Laboratories. Technical Report CWLR 2365 Army Chemical Center, MD. HELLREICH, A., GOLDMAN, R.H., BOTTIGLIERI, N.G., and WEIMER, J.T. (1967) The effects of thermally generated CS aerosols on human skin. Edgewood Arsenal Technical Report EATR 4075, 1967. Edgewood Arsenal, Maryland: Medical Research Laboratory. LEE, R.J., YOLTON, R.L., YOLTON, D.P., SCHNIDER, C., and JANIN, M.L. (1996) Personal defense sprays: effects and management of exposure, J. Am. Optom. Assoc., 67(9): 548–560. LEENUTAPHONG, V. and GOERZ, G. (1989) Allergic contact dermatitis from chloroacetophenone (tear gas), Contact Derm., 20(4): 316. PENNEYS, N.S., ISRAEL, R.M., and INDGIN, S.M. (1969) Contact dermatitis due to 1-chloroacetophenone and chemical mace, New Engl. J. Med., 281(8): 413–415. PUNTE, C.L., WEIMER, J.T., BALLARD, T.A., WILDING, J.L. (1962) Toxicologic studies on o-chlorobenzylidiene malononitrile, Toxicol. Appl. Pharm., 4: 656–662.


RIOT CONTROL AGENTS

SANFORD, J.P. (1976) Medical aspects of riot control (harassing) agents, Ann. Rev. Med., 27: 421–429. STOPFORD, W. and Bunn, W.B. (1989) Effects of Exposure to Toxic Gases – First Aid and Medical Treatment, 3rd edition, Secaucus, New Jersy: Matheson Gas Products. THORBURN, K.M. (1982) Injuries after use of the lacrimatory agent chloroacetophenone in a confined space, Arch. Environ. Health, 37(3): 182–186. WEIGAND, D.A. (1969) Cutaneous reaction to the riot control agent CS, Mil. Med., 34: 437–440. WINOGRAD, H.L. (1977) Acute croup in an older child. An unusual toxic origin, Clin. Pediatr. (Phila), 16(10): 884–887.


APPENDIX

Table of Riot Control Agent Formulations

C

TABLE C.1 Representative defense spray formulations characterized by active ingredient, excipients (carriers/solvents, dyes), and propellents. Data derived from manufacturers material safety data sheets (MSDS) Riot control agent

Product name

Manufacturer

Active ingredient (CAS#)

Excipients (CAS #)

Propellant (CAS#)

DEF-TEC Corp 2399 Forman Road Rock Creek OH Mace Security International Bennington VT

Chloroacetophenone (532-27-4)

Potassium chlorate (3811-04-9)

Chloroacetophenone (532-27-4) 1%

Sec Butanol (78-92-2) 20% Propylene glycol (57-55-6) 20% Limonene (5989-27-5) 20% Dipropylene glycol monomethyl ether (34590-94-8) 30% Hydrochloric acid (7647-01-1) LT 3.5% Water (7732-18-5)

Defense spray formulations CN

CN (original Mace)

CN

MACE CN

CNS

Chlor-o-pic

CS

SGA-100 Ferret

CS

SGA-400 Ferret

Great Lakes Chemical Corp 2200 Highway 52 NW West Lafayette IN AAI Corp Hunt Valley MD AAI Corp Hunt Valley MD

Chloropicrin (76-06-2) GT 96.5%

Chlorobenzylidene malononitrile (2698-41-1) 11% Chlorobenzylidene malononitrile (2698-41-1) 10%

Methylene chloride (75-09-2) 71% Methylene Chloride (75-09-2) 84% Dye (unspecified) 6%

(continued)


RIOT CONTROL AGENTS

TABLE C.1 (continued) Riot control agent

Product name

Manufacturer


Excipients (CAS #)

CS

Blast Agent – CS

Liquid agent CS

Chlorobenzylidene malononitrile (2698-41-1) given as (40915-55-7) Chlorobenzylidene malononitrile (2698-41-1) 25%

Magnesium oxide (1309-48-4)

CS

Defense Technology Corp of America Casper WY DEF-TEC Corp 2399 Forman Road Rock Creek OH

CS

NAPA#7651787 Qualco#993-C Tear Gas Sabre Defence

Qualco Products 137 South Ave Fanwood NJ Security Equipment Corporation 330 Sun Valley Circle Fenton, MO Smith & Wesson Chemical Co, Inc 2399 Forman Rd Rock Creek OH United Defense Industries 225 W Deer Valley Rd Phoenix AZ United Defense Industries 225 W Deer Valley Rd Phoenix AZ United Defense Industries 225 W Deer Valley Rd Phoenix AZ Security Equipment Corporation 330 Sun Valley Circle Fenton, MO

Chlorobenzylidene malononitrile (2698-41-1) LT 1% Chlorobenzylidene malononitrile (2698-41-1)

CS

CS

Pepper FogCS Special

CS

Paralyzer W207

CS

Paralyzer WKR

CS

Paralyzer X621

CS–OC

Sabre Defence

OC

Pepperfoam 10%


Mace Security International Bennington VT

Methylene chloride (75-09-2) 75% Rodamine-dye Mineral oil (8012-95-1) GT 90% DymelR 134a (1,1,1,2-tetrafluoroethane) (811-97-2)

Chlorobenzylidene malononitrile (2698-41-1)

Cyclohexanone (108-94-1) Glyceryl triacetate (102-76-1)


Methylene chloride (75-09-2) Light petroleum oil





Chlorobenzylidene malononitrile (2698-41-1) Oleoresin capsicum (8023-77-6) 2,000,000 SHU Capsaicin (404-86-4) LT 15%

Propellant (CAS#)

DymelR 134a (1,1,1,2-tetrafluoroethane) (811-97-2)

Propylene glycol (57-55-6) LT 50% Isopropanol (67-63-0) GT 5% 2,2-iminodi ethanol (111-42-2) GT 5%

TABLE OF RIOT CONTROL AGENT FORMULATIONS

Riot control Product name agent

Manufacturer


Excipients (CAS #)

Propellant (CAS#)

OC

Water Based Pepper Spray

Mace Security International Bennington VT

Oleoresin capsicum (8023-77-6) 5–10%

Nitrogen (7727-37-9) 0.1%

OC

Sabre Defence

Security Equipment Corporation 330 Sun Valley Circle Fenton, MO

OC

Cap-Stun

Zarc International, Inc Gaithersburg MD

Oleoresin Capsicum (8023-77-6) 5.5–10% 500,000– 2,000,000 SHU Oleoresin Capsicum (8023-77-6) 5.5%

Propylene glycol (57-55-6) 5–45% Isopropanol (67-63-0) 5–25% Water (7732-18-5) 45–65% UV Dye 0.1% UV Dye

DymelR 134a (1,1,1,2-tetrafluoroethane) (811-97-2)

Isopropanol (67-63-0) 64%

Isobutane/ propane (75-28-5) 30.5%

Potassium chlorate (3811-04-9) Diatomaceous earth (61790-53-2) Magnesium carbonate (546-93-0) Potassium bicarbonate (298-14-6) Sodium bicarbonate (144-55-8) Sucrose (57-50-1) Potassium chlorate (3811-04-9) Diatomaceous earth (61790-53-2) Magnesium carbonate (546-93-0) Potassium bicarbonate (298-14-6) Sodium bicarbonate (144-55-8) Sucrose (57-50-1)

Nitrocellulose (9004-70-0)

Pyrotechnic formulations CN

CN Smoke Mix Federal 206 Long Laboratories range Saltsburg PA projectile

Chloroacetophenone (532-27-4)

CN

CN Smoke Mix Federal 219/70 Yard Laboratories projectile Saltsburg PA

Chloroacetoph enone (532-27-4)


(continued)


RIOT CONTROL AGENTS

TABLE C.1 (continued) Riot control agent

Product name

Manufacturer


Excipients (CAS #)

Propellant (CAS#)

CN

Pyrotechnic CN agent

Lake Erie Component Co Forman Rd Rock Creek OH

Chloracetophenone (532-27-4)


CS

Blast Agent – CS

CS

Pyrotechnic CS agent

Defense Technology Corp of America Casper WY Defense Technology Corp of America Casper WY

Chlorobenzylidene malononitrile (2698-41-1) given as (40915-55-7) Chlorobenzylidene malononitrile (2698-41-1)

Potassium chlorate (3811-04-9) Magnesium carbonate (546-93-0) Sucrose (57-50-1) Magnesium oxide (1309-48-4)


CS

SGA-100 Ferrett Barricade Penetrating 12 Gauge

Federal Laboratories Saltsburg PA

Chlorobenzylidene malononitrile (2698-41-1) 3%

CS

SGA-400 Ferrett Barricade Penetrating 40 MM Cartridge

Federal Laboratories Saltsburg PA

Chlorobenzylidene malononitrile (2698-41-1) 3%

Potassium chlorate (3811-04-9) Magnesium carbonate (546-93-0) Sucrose (57-50-1) Methylene chloride (75-09-2) 96% Basic violet 10 dye (81-88-9) 1% Methylene Chloride (75-09-2) 96% Basic violet 10 dye (81-88-9) 1%

Note The editors are indebted to Dr. Russell Mankes and Dr. Kristina Mankes for Appendix C.


Subject Index absorption see uptake/distribution of RCAs acrolein (papite) 5 acute medical care 247-8, 336-7 acute pulmonary effects see pulmonary effects acute toxicity of capsaicin 126-9 of chloroacetophenone (CN) 85 of chlorobenzylidene malononitrile (CS) 80-2 of dibcnz|b,f|l:4-oxazepine (CR) 84-5 of oleoresin capsicum (OC) 125 adamsite .sir diphenylaminochloroarsine adrenals and CS exposure 95 and CS-induced morphologic changes 95 and reproductive function 95 adsorption isotherm 309 advisories and promulgations federal 284 state 285 aerosol subject restraints see personal protective sprays agitated individuals 322 alcohol 322 algae 300 alkylating agents (SN-, tvpe) CN as 50 CS as 49, 50 alkylation 47 allergic contact dermatitis and CN exposure 94 and CS exposure 92-3 Ames assay 184 analysis of modern RCAs CN 2 7-8 CR30 CS29 OC 30-1 analysis of obsolete RCAs BA31 SK32 aquatic toxicity of CR 305 of CS 300-2 arene oxides 45, 46 arsenic, developmental toxicity 166-7 artillery projectiles 18

assessing/characterizing risks of RCAs 259-71 asthma animal model for 73 and OC exposure 73 PS irritants 73 bacterial mutation 184 batons 322 behavioral teratogenesis 161, 174 Bezold-Jarrish reflex 128 bioassays for peripheral sensory irritants 67-8 biodegradation of capsicum compounds 307-8 bioinformatics 319 biological interactions of capsaicin/capsaicinoids 52-5 of chloroacetophenone (CN) 51-2 of chlorobenzylidene malononitrile (CS) 49-51 of dibenz[b,f]l:4-oxazepine (CR) 51-2 of oleoresin capsicum see capsaicin/capsaicinoids biomedical criteria 241-4 biotransformation see metabolism Bishop of Munstcr 231 blepharitis 87 blepharospasm 4, 65, 86, 97, 132, 277 blepharospasm test 67 blistering and CN exposure 94 and CS exposure 92 blood cyanide levels and CS exposure 50 and thiocyanate 84 bradykinin release 51 bromoacetone (BA) 5 bromobenzyl cyanide (CA) 5, 86 bronchial hyper-responsiveness 125 bronchoprovocation testing 90 camite 2, 7 capsaicin absorption see capsaicin, uptake/distribution acute toxicity 126 and apnea 128 and chemoprotective properties 53-4

SUBJECT INDEX

capsaicin {Continued) and cytochrome P-450 enzymes 53 and desensitization 128, 129 and effects on neuropeptides 52-3, 128 and formation of reactive intermediates 54-5 and gastrointestinal tract 129 and inhibition of monoxygenases 53 and Kratschmer reflex 128 and neurogenic inflammation 71, 126-7 and nociceptors 127 and non-sensory neurons 127 and ocular effects 71 and protective reflexes 128 and pulmonary function/mechanics 127 and release of bioactive compounds 52, 128 and sensory neurons 126, 127 and substance Ρ 52-3, 128 and suprathreshold levels 124 and thermoregulation 128-9 and treatment of chronic rhinitis 201 diabetic neuropathy 201 post-herpetic neuralgia 201 and vaniMoid receptor 52, 126 anti-carcinogenic effects of 54, 192-3 byconversion to reactive intermediates 54-5 capsaicin antagonists 128 carcinogenicity 130 cardiovascular effects 128 chemistry 124 chemoprotective properties of 53-4 co-carcinogen icity 192-3 detection in biological matrices 31 genotoxicity of 191-6 LDS0 values 126 mechanisms/interactions 52-5, 192 metabolism 47 metabolites of 47 mutagenicity 193-6 neurotoxicity 126-7 nutritional impacts of 129 ocular effects of 71, 124-5 pathological effects 154 pharmacology/toxicology animal 125-9 human 133-4 physiological effects of species differences 128 pulmonary toxicology 127-8 repeated-dose toxicity 129-30, 153-5 sensory irritant effects 71, 72-3, 124-5 synthesis of 30 uptake/distribution 39

capsaicinoids 27, 123-5, 307 capsaicin-sensitive neurons functions of 127 pathophysiology of 127 capsazepine 128 Capsicum annuum 123 Capsicum frutescenes 123 Capsicum japonicion 224 Capsicum minimum 222 Cap-Stun® 8 Cap-Tor® 8, 12 carcinogenicity of capsaicin 192-3 of chloroacetophenone (CN) 190 of chlorobenzylidene malononitrile (CS) 190 of dichloromethane 103 of isopropyl alcohol 106 of methyl isobutyl ketone 105 of polyethylene glycols 108 cardiovascular system and effects of capsaicin 128 and effects of CR 85 carriers/solvents see also solvents dichloromethane (methylene chloride) 100-4 isopropyl alcohol (isopropanol) 105-6 methyl isobutyl ketone 104-5 polyethylene glycols 107-8 propylene glycol 106-7 1,1,1-trichloroethanc 108-9 cartridges 18-19 cation channel 52 centrally acting pharmacological agents 234 CFCs see chlorofluorocarbons c-fibers 155,201 CH see tropilidene Chechen rebels 250 chemical analvsis of capsaicinoids 30 of chloroacetophenone (CN) 27-8 of chlorobenzylidene malononitrile (CS) 29 of CS thermal decomposition products 98 of dibenzlb,f]l:4-oxazepine (CR) 30 of oleoresin capsicum (OC) 30-1 chemical mixtures 96 chicken embryos - CN effects on 162 chili peppers 145, 155, 202 Chinese hamster ovary (CHO) 185, 189 chlorine gas 5 chloroacetone (A-stoff) 5 chloroacetophenone (CN) absorption see chloroacetophenone, uptake/distribution

SUBJECT INDEX acute toxicity 85 as an alkylating agent 47 analysis 27-8 aquatic toxicity 304 carcinogenicity 190 chronic toxicity/long-tcrm effects 145-9 clinical chemistry 51-2 dermatitis 94, 274 environmental fate in the atmosphere 304 environmental fate in soil 303-4 environmental fate in water 304 genotoxicity 190 historical development 85 immunotoxicology 95 inhalation I.Ctso values 82, 85 lung effects and injury 91, 204-5 mechanisms/interactions 51-2 metabolism 46-7 microbial degradation 302 mutagenicity 190 occupational exposure 273-4 occupational standards for 284 ocular effects and injury 70-1, 86, 87-8, 204 organ specific toxicity 87-8, 91, 94 pathological effects 87-8, 91, 94, 145-6 physico-chemical properties 26, 27 physiological effects 85, 202 repeated dose toxicity 145-6 reproductive/developmental effects 162-3 sensory irritant effects 70-1, 72, 74 skin effects and injury 94, 203 synthesis 26 uptake/distribution 38 o-chlorobenzylidene malononitrile (CS) absorption see o-chlorobenzylidene malononitrile, uptake/distribution acute toxicitv 80-2 as an alkylating agent 49, 187 analysis 29 aquatic toxicity 300-2 bradykinin release 51 carcinogenicity 190 cell cycle perturbations 50-1 chest problems 275 chronic toxicitv/long-term effects 89, 149-51 cutaneous effects see o-chlorobenzvl idene malononitrile, skin effects cyanide formation [in vivo) 83, 84 cyanide/thiocyanate levels (in vivo) 84 cyanogenic properties/potential 49-50, 83-4 J

decomposition products see pyrolysis products of dermatitis 274 endocrine toxicology 95-6 environmental fate in soil 300 environmental fate in the atmosphere 302 genotoxicity 183, 187-90 historical development 80 immunotoxicology 94 inhalation LCt50 values 81-2 lung effects and injury 81, 88-91, 207 10 mechanisms/interactions 49-51 metabolites of 43-4 mutagenicity 189-90 occupational exposure 274-6 occupational standards for 284 ocular effects and injury 69, 86-7, 206-7 organ specific toxicitv 80-1, 86-7, 88-91, 92-3 pathological effects 80, 89, 150 physico-chemical properties 26, 28-9 protein binding and genotoxicity 187, 189 pyrolysis products 29, 97-8 repeated dose toxicity 149-50 reproductive/developmental effects 163-5 sensory irritant effects 69, 72, 74 skin effects and injury 74, 92-3, 210-12, 274-5 synthesis 28 uptake/distribution 37-8 thermal decomposition 83, 97-8 2-chlorobenzylidene malononitrile see o-chlorobenzylidene malononitrile chlorofluorocarbons (CI Cs) 9, 99 2-chloro-l-phenyicthanone see chloroacetophenone chloropicrin (trichloronitromethane, PS) 5 chromosomal aberration 185, 189 chronic toxicity/long-tcrm effects of capsaicin 153-5 of CN 145-9 of CR 152-3 of ( 3 149-51 of OC 155-6 of VAN 156-7 cinnamic acid smoke 234 civil order (disturbance) 248 classification see riot control agents, classification of clinical chemistry effects of CN 51-2 of CR 51-2

• 345

SUBJECT INDEX combination products CNB7 CNS7 comet assav 185 comparative toxicity of common RCAs 90-1 competent authorities 249 computational toxicology 318 confined environments/space 309 contact dermatitis see dermatitis corneal injury on exposure to RCAs 86 corticosterone levels and CS 94 cough 154,219 covalent interactions 187 cross reactivity 93 crowd control techniques I, 233-4 crowd/riot control 22 CS see o-chlorobenzvlidene malononitrile CS2 82, 274 CS degradation products detection and identification of 98 toxicity of 98 Ct 81 Ct 50 81 cutaneous toxicology 91-4 cyanide biochemical interactions 50 blood cyanide levels 50 detoxification/metabolism 83, 84 effects of 49-50 mcchanism-of-action 49-50, 83 as a product of CS metabolism 43-4, 83 target organs 49 toxicity 83 cytochrome c oxidase 49, 50 cytochrome P-450 40 Daphnia magna 305 decontamination 247-9, 335-6 decontamination products 12 defense spray propellants 109-11 defense sprays see personal protective sprays degradation products 12 dermal effects see skin effects dermal sensorv irritation 73-4 dermatitis and CN exposure 148 dermatotoxicology see cutaneous toxicology desensitization and capsaicin 52 detection of capsaicin in biological matrices 31 dibenz[b,f] 1:4-oxazepine (CR) absorption see diben/.[b,f) 1:4-oxazcpine (CR), uptake/distribution acute toxicity 84-5

346 •

analysis 30 aquatic toxicity 305 chronic toxicity/long-term effects 152-3 clinical chemistry 51-2 environmental fate and degradation 304-5 genotoxicity 190-1 inhalation LCtS0 values 82 lung effects and injury 91, 216 mechanisms/interactions 51-2 metabolism 44-6, 305-6 metabolites of 45-6 microbial degradation 305 mutagenicity 191 ocular effects and injury 69-70, 87, 216 organ specific toxicity 87, 91, 93 pathological effects 152-3 physico-chemical properties 26, 30 repeated dose toxicity 152-3 reproductive/developmental effects 167 sensory irritant effects 69-70, 72, 73 skin effects and injury 93, 216-17 synthesis 30 uptake/distribution 38 dichloromethane (methylene chloride) acute toxicity 100-2 carcinogenicity 103 disposition and metabolism 102-3 mutagenicity 103 neurotoxicity 100 ocular effects 100 repeated-dose toxicity 102 reproductive and developmental effects 104 target organ toxicity 100 dietary phytochemicals 53 dihvdrocapsaicin 27, 307 dihydro CS 43, 98 diphenylaminochloroarsine (DM, adamsite) general aspects 6 historical aspects 5 ocular and cutaneous effects of 6 physiological effects and toxicology 6 reproductive/developmental effects 166-7 diphenylchlorarsine (DA) 6 diphenylcyano-arsinc (DC) 6 dispensers aircraft-mounted 19 man-portable 19 personal-protection 20 vehicle-mounted 19 dispensing systems and dispersion devices 8-10, 17-20,239 dissemination 5, 238-9 DM see diphenylaminochloroarsine

SUBJECT INDEX DNA and interactions with reactive metabolites 49

DNA damage 186 DNA fragmentation 186 DNA microarrav 317 DNA repair 186 dose-response assessment 263-6 drenches 74 dyes disperse red (9) 234 occult 234 marking 234 solvent green (9) 234 solvent yellow (33) 234 Dymel® (1,1,1,2-tetrafluoroethane) 9 EBA see ethyl bromoacetate effectiveness 235 electrophilic metabolites 48 embryonic development CN effects on 162-3 CS effects on 163-5 endocrine physiology and stress 95 endocrine toxicology CS-induced endocrine toxicity adrenals 95 thvroid 95-6 physical stresses and endocrine function 95 environmental fate/degradation of CN and CS 300, 302-4 of oleoresin capsicum (OC) 307-8 environmental issues 299-315 ethyl bromoacetate (EBA) 6, 232 ethyl iodoacetate (SK) 6, 27 expert witness 251 exposure variables individual factors 266 interindividual factors 266-7 physical form of agent and delivery system 266 setting (scenario) 266 eye effects/injury see ocular effects, ocular injury fathead minnow (Pimephales promelas) 305 federal statutes 283 Federal streamer® 239 fentamyl 250 forensic aspects 231-8 forensic specialists 233 formulations liquid 96 powder 96 pyrotechnic 96

framework - risk characterization .Sir risk characterization framework frangible missile 234 fresh water ecosystems 305 frog flexor reflex assay 67 gas chromatography-mass spectrometry (GC-MS) 29, 31 genetic toxicity 183-200 Geneva convention 232 Geneva protocol 231, 281 genomics 317-19 genotoxicity of capsaicin 191-6 of chloroacetophcnone (CN) 190 of chlorobenzylidene malononitrile (CS) 187-90 of dibenz[b,f]l:4-oxazepine (CR) 190-1 genotoxicity tests bacterial mutation assays 184 DNA damage 185 DNA repair 186 mammalian cell mutation assays 184-5 micronuclei formation 185-6 whole animal assays 186 ^-glucuronidase 89 glutathione (GSH) depletion 51 glycols and derivatives 106 goldfish (Carassius auratus) 301 Greek fire 231 Green Cross 1 6 grenades 18 Guardian® 8 half-life (T. n) Of diben/.[b,f] 1:4-oxazepine (CR) 38 hand-held devices see personal protective sprays harassing agents 1 hazard identification 262 health care facilities/hospitals 246 health concerns related to carriers/solvents 98-100 related to riot control agents 79-80 health risks of RCAs 281 heat shock protein in maternal stress and teratogenesis 176-7 Hensons node 162 HGPRT 185, 191 Himsworth Committee 232, 241 historical perspectives 5-8 homocapsaicin 27, 307 homodihydrocapsaicin 27, 307 Hong Kong 246 human exposures to RCAs 201-30

• 347

SUBJECT INDEX human pharmacology/toxicology of capsaicin 217-21 of chloroacetophenone (C.N) 202-3, 204-6 of chlorobenzvlidene maiononitrile (CS) 206-15 of dibenz|b,fJl:4-oxazepine (CR) 215-17 of oleoresin capsicum (OQ L31-3, 220-4 Hunan hand 276 Hunvadi 231 h yd roge η cya η i de as a CS pyrolysis product 98 toxicity of 83 hydrolysis rate of CN 3 ofCR3 of (:S 3 IC S0 sec incapacitating concentration ICt 5 0 81 ICt^o values for CS 206 immunotoxicitv and CN exposure 95 and CS exposure 94 effect on antibody response 94 effect on humoral immune response 94 incapacitating concentration 81 in-custodv deaths and ()C (pepper spray) use 132, 223 informatics see bioinformatics injuries and RCA use chemical 245-6 physical 244-5 intrauterine growth retardation (IUGR) 164, 165 iodoacetone 6 ion flux 52 irritants and confined environments 309 isopropanol see isopropyl alcohol isopropyl alcohol acute toxicity 105 carcinogenicity 106 disposition and metabolism 105-6 mutagenicity 106 ocular effects 105 repeated-dose toxicity 105 isovelleral 128 Keratitis 153 Kratschmer reflex 128 lachrymators sec lacrimators lacrimators 1, 26 lacrimatory compounds see lacrimators lactams 45

348

laryngotracheobronchitis 248 law enforcement use/application of RCAs 22-3 LCt 50 81 LD50 (lethal dose 50) 107, 126, 241 Leicester 245 less-than-lethal weapons (devices) 286-7 factors in selection 287 lethal concentrations of CN 82 of CR 82 of CS82 of oleoresin capsicum 125 lipid peroxidation 55 liquid projection devices 239 Livens projector 17 Londonderry riots 232 low friction polymers 234 lung effects see pulmonary effects lung lavage fluid 89 lung washings see lung lavage fluid lysosomal activity and /3-glucuronidase 89 and lung injury 89 Mace® 7, 10, 147,239 male reproductive toxicity and chloroform 1 73 andCS 165 malodorants (malodorous substances) 234 maiononitrile 43, 44 mammalian cell mutation 184-5 managing chemical risks - approaches precautionary approach 291, 293 quantified exposure limits and monitoring controls 291 risk communication 293 managing riot control agent risks strategies for 293-6 margin-of-safctv (safety ratio) 4, 289, 290 markers 234 modes-of-action/mechanisms 47-8 medical examiner 233 medical management after exposures to RCAs 247-8, 336-7 metabolic pathways see metabolism metabolism of capsaicin 47 of chloroacetophenone (CN) 46-7 of 2-chlorobenzylidene maiononitrile (CS) 43-4 of dibcnz(b,f]l:4-oxazepinc (CR) 44-6 phase I enzyme systems in 41 phase II conjugation reactions of 42

SUBJECT INDEX metabolites of capsaicin 47 of chloroacetophenone (CN) 46 of 2-chlorobenzvlidene malononitrile (CS) 43-4 of dibcnz|b ; f|l:4-oxazepine (CR) 45-6 1-methoxycycloheptatriene (CHT) see tropilidene

methylchloroform see 1,1,1 -trichloroethane methylene chloride see dichloromethane methyl isobutyl ketone (M1BK) acute toxicity 104 carcinogenicity 105 dermal effects 104 developmental/reproductive effects 168-9 disposition and metabolism 105 mutagenicity 105 repeated-dose toxicity 104-5 target organ toxicity 104 in ethyl salicylate 131 microbial degradation capsicum products 308 of CN 302 microextraction 29 micronuclei formation 185-6 microsomal monoxygenases 40 military use/application of RCAs 20-1 MMAD (mass median aerodynamic diameter) 238 modalities for crowd control see riot control techniques modes-of-action/biological interactions of RCAs 47-55 molten CS 81 mortars 18 Moscow 250 mounted dispensers 19 multiple chemical exposure 96 mumichog {Fundulus lieteroclitus) 301 mutagenicity see genotoxicity National Institute of justice (NIJ) 11, 287, 288 neocil 164 neurobehavioral teratogenicity 161 neurogenic inflammation 126-7, 155 neuropeptides calcitonin gene-related peptide 52, neurokinin A 52 substance Ρ 52-3 neuropeptides and capsaicin 52 NIH-shift 46 NIOSH recommendations and the manufacture of RCAs 279 nonivamide (synthetic capsaicin) 1, 11, 123

non-neural tissues and vanilloid receptor-like proteins 126 norhydrocapsaicin 27 Northern Ireland 232 nucleophilic moieties (sites) 49, 65 obscuring smoke cloud agents 234 obsolete riot control agents 31-2 OC see oleoresin capsicum occupational controls and medical surveillance 296 occupational exposure to RCAs 273-80 OC sprays capsaicinoid content 11 development 11 ocular effects of capsaicin 71, 124-5 of chloroacetophenone (CN) 87-8 of chlorobenzviidene malononitrile (CS) 86-7 of dibenz[b,f]l:4-oxazepine (CR) 87 of oleoresin capsicum (OC) 71, 124, 131-2,220-1 ocular injury and action of RCAs 68-9 and chemicals 85-6 and corneal proteins/enzymes 86 and methods of dissemination 86 and tear gas devices 86 ocular injurv/lesions sec under individual RCAs ocular irritancy .sec under individual RCAs ocular irritancy thresholds 3 ocular sensorv irritation 68-71 oleoresin capsicum (OC) absorption see oleoresin capsicum (OC), uptake/distribution acute effects 124-5 biodegradation 307-8 capsaicin content 125 capsaicinoid analog content 124, 125, 307 carcinogenicity 130 chemistry 306-7 chest problems 277 composition 123-4, 307 ecotoxicity 308-9 eye effects 131-2, 220-1, 277 LCtS0 125 mutagenicity 130 occupational exposure 276-7 pharmacology/toxicology 125 repeated dose toxicity 129-30, 156 reproductive/developmental toxicity of 130, 165-6 sensory irritant effects 71, 72-3 uptake/distribution 39

SUBJECT INDEX olfactory compounds see malodorants onset-of-action of common RCAs 3 opacification and CN exposure 87 operational effectiveness 235, 240 operational use and safety considerations 239-41 ophthalmic toxicology 85-8 organ-specific effects see individual RCAs OSHA hazard communication standard 278 OSHA respiratory protection standard 279 OSHA workplace criteria CN284 CS284 P-450 enzvmes 40-1 Paralyzer®239 particle size 202 patch testing 93 pathological effects/changes on exposure to CN 87-8, 91, 94 on exposure to CR 87, 91, 93 on exposure to CS 86-7, 88-91, 92-3 PAVA .str nonivamide peace-keeping operations agents used in 233-4 injuries/mortalities 244-6 medical management of casualties 246-9 role of competent authorities 249-50 role of the forensic expert 251-2 PEG-200 107-8 PEG-400 107 pepper gas see pepper spray pepper spray 123 pepper-spray products analysis of 30-1 peripheral sensory irritants (PSI) 1, 65-7, 233-4, 235-8 characteristics 65 modc-of-action 65 pharmacological actions 65-6 peripheral sensory irritation bioassavs for 67-8 persistent effects (animal) dermal acute exposure to CN 148-9 acute exposure to CS 151 ocular acute exposure to capsaicin 155 acute exposure to CN 147-8 acute exposure to CR 153 acute exposure to CS 150-1 acute exposure to VAN 157

350 •

respiratory acute exposure to CN 148 acute exposure to CS 151 persistent effects (human) dermal acute exposure to CN 205 acute exposure to CS 214-15 acute exposure to OC 224 ocular acute exposure to CN 204 acute exposure to CS 212 acute exposure to OC 222 respiratory acute exposure to CN 204-5 acute exposure to CS 212-14 acute exposure to OC 222-3 personal defense sprays see personal protective sprays personal protection dispensers see personal protective sprays personal protective sprays active ingredients in 10-12 carriers/solvents in 9 effects of 8 formulations 8, 96 propel I ants in 9 spray patterns 10 toxicity of 96-7 types 8 phagocytosis 95 pharmacokinetics/pharmacodynamics 37-9 pharmacology/toxicology of CS, CR and CN 79-96 pharmacology/toxicology of OC, capsaicin, and capsaicinoids 123-43 phase 1 metabolism 40-2 phase II metabolism 40, 42-3 phosgene 5 physico-chemical properties of capsaicin 3 of chloroacetophenone 3 of o-chlorobenzvlidene malononitrile 3 of dibenz|b,f] l:4-oxazcpinc 3 phytoplankton 302 plethysmograph test 67-8 Plutarch 231 Paris 232 polyethylene glycols acute toxicity 107 carcinogenicity 108 developmental/reproductive effects 108 disposition and metabolism 108 mutagenicity 108 repeated-dose toxicity 107-8 populations at risk to RCAs 292 portable dispensers 19

SUBJECT INDEX positional asphyxia 132 potency 235-7 primary metabolism .sir phase I metabolism progression-of-force 286 propellants - defense spray butane 110 isobutane 110 nitrogen 110 propane 110 1,1,1,2- tetrafluoroethane 110-11 propylene glycol acute toxicity 106 developmental/reproductive effects 106-7 disposition and metabolism 106 mutagenicity 106 repeated-dose toxicity 106 protective reflexes 128 protein expression 318 proteomics 317-19 PSI see peripheral sensory irritants public health goals 282 pulmonary effects of capsaicin 127-8 of chloroacetophenone (CN) 91 of chlorobenzvlidene malononitrile (CS) 88-91 of dibenz|b,f]l:4-oxazepine (CR) 91 of oleorcsin capsicum (()(.) 125 pulmonary sensory irritation 71-3 pulmonary system, responses to xenobiotics 88 pulmonary toxicology 88-91 pyrolysis products see thermal degradation products pyrotechnic dissemination of CN 18 of CS 18 pyrotechnic mixtures of CN 96 of CS 96 toxicity of 96 quinones deleterious/toxic effects 54 and GSH depletion 54 and lipid peroxidation 55 mechanism of action 54 and protein alkylation 54 RADS see reactive-airways dysfunction syndrome rainbow trout 301 RCAs see riot control agents RD5„ 65, 67

reactive-airways dysfunction syndrome 89-90, 248 and CS exposure 89 reactive intermediates methyl radical 48, 55 phenoxy radical 48, quinones 48, 54-5 reactive oxygen species (ROS) 48, 55 reflexes local 65 systemic 65 regulatory status and worker protection 278-9 repeated-dose toxicity of capsaicin 129-30, 153-5 ofCN 145-6 of CR 152-3 of CS 149-50 of oleoresin capsicum 129-30, 156 reproductive and developmental toxicology of adamsite 166-7 of carriers/solvents benzene 171-2 butanol 173 carbon tetrachloride 172 chloroform 172-3 cyclohexanone 171 dichloromethane (methylene chloride) 168 dipropyplcnc glycol monomethyl ether 171 iminodiethanol 170 isopropanol 169 limonene 170 methyl isobutyl ketone (MIBK) 168-9 mineral oil 171 propylene glycol 169-70 of chloropicrin 167 of propellants dymel 173-4 of riot control agents chloroacetophenone (CN) 162-3 chlorobenzvlidene malononitrile (CS) 163-5 dibenz[b,f]l:4-oxazepine (CR) 167 oleoresin capsicum (OC) 165-6 residue analysis of chloroacetophenone (CN) 29 of chlorobenzvlidene malononitrile (CS) 29 rhodanese 83 riot control chemically-based means 1 non-chemical means 1 riot control agents (RCAs) carcinogenicity 190, 192-3

SUBJECT INDEX riot control agents (RCAs) (Continual) characteristics of 2 classification of 13, 232 degradation and decontamination products 12 dermal sensory irritation 73-4 effects of intended 262 unintended 262 emerging concepts/trends 324-5 formulations 339-42 as liquid formulations 96 as pyrotechnic mixtures 96 toxicology of 96-7 health risks considerations 290 issues/concerns related to 321-3 law enforcement use and application 22 metabolism of 39-47 military use and application 20-1 ocular sensory irritation 68-71 physiological actions 2-5 public health considerations 281-2 pulmonary sensory irritation 71-3 reproductive and developmental toxicology 161-81 risk management 293-4 as stressors 174 synthesis and chemical analysis 25-36 risk characterization framework dose-response assessment phase 263-5 effects identification phase 262-3 exposure assessment phase 265-8 risk characterization phase 268-70 risk communication 293 risk management/public health considerations of RCAs 281-98 risk models 260 risks intentional exposure 262 unintentional exposure 262 niRNA expression 318 Royal Ulster Constabulary 232 Ruthenium Red 128 S9 fraction 184 safety index see margin-of-safety Scoville Heat Units (SHU) 11, 71 secondary metabolism see phase II metabolism self-defense sprays see personal protective sprays sensitization and exposure to CN 147, 203, 205-6 and exposure to CS 150, 212, 215 and exposure to OC 156 sensorv irritation 71, 72-3, 124-5

352 •

sensory neurons and capsaicin 126 and neuropeptides 126 settling effects 11 SH-containing enzymes 47 sheep red blood cells (SRBC) 94 Sherrington pseudoaffective response 89 sister chromatid exchange 188 skin effects of capsaicin 125, 154-5, 220 of CN 94 of CR 93-4 of CS 92-3 ofOC 75, 124, 156,223-4 skin sensitization and CN 94, 203, 205-6 and CS 92-3, 212, 215 smoke grenade, obscuring 234 Snellen visual acuities test 220 solubilities of common RCAs 3 solvents see also carriers/solvents acute toxicities 101 additives 99 carcinogenicity 101 developmental/reproductive effects 101 impurities 100 irritation 101 mutagenicity 101 target organ toxicity 101 toxic effects 99-100 sorption irritants and sorption onto building materials 309-10 sorption and desorption processes 310 sorption equilibrium 309-10 sorption of mixtures 310 state regulations/standards set' advisories and promulgations sternutators 32-3 strategics for managing RCA risks 293-6 stress and birth defects 175 stress as a co-teratogen 175-6 stress and developmental effects/ reproductive function 174-7 stress as a developmental toxin 175 stress and riot control agents 174 S. typhlmurtum (Ames) test and capsaicin 193, 194 and chloroacetophcnone (CN) 190 and chloroben/.vlidene malononitrile (CS) 189-90 and dibenz[b,f)l:4-oxazepine (CR) 191 substance Ρ and capsaicin 52-3 and c-fiber stimulation 53 and lung effects 53 and neurogenic inflammation 53

SUBJECT INDEX and responses 53 sulfhydryl (SII) group 47, 50 suprathreshold dose and capsaicin-induced neural damage 126 and CN-induced skin injury 97 synthesis ' of BA 31 of CA 32 of capsaicin 30 of chloroacetophenone (CN) 26 of u-chlorobenzvlidene malononitrile (CS) 28-9 of DA 33 of DC 33 of dibenz[b,fJl:4-oxazepine (CR) 30 of DM 33 of PS 31-2 of SK 32 synthetic capsaicin sec nonivamide tachykinins 53 tachyphylaxis 66, 133, 154, 219 TCso see threshold concentrations tear agents (gases) 5-6 tear gas gun injuries 203-4 1,1,1,2-tetrafluoroethane (halocarbon 134a) genotoxicity of 111 toxicity of 110-11 thermal degradation products of CS 97-8 thin layer chromatography (TLC) 30 thiocyanate excretion 50 formation 44, 83 serum levels 44, 84 thiol enzymes and lacrimatory compounds 50 threshold concentrations (eye irritation) CN3 CR3 CS3 thyroid CS-induced effects 95-6 physical stressors 95 thyroid stimulating hormone 95 TLC see thin layer chromatography toluene diisocvanate 65 toxic metabolites and adverse effects 48 toxicology of capsaicin 125-9 of carriers/solvents 98-109 ofCN85, 87-8, 91,94, 95 of CR 84-5, 87, 91,93-4 of CS 80-4, 86-7, 88-91, 92-3, 94, 95-6

of oleoresin capsicum 125 of propellants 109-11 of RCA formulations (self-defense sprays) 96-7 of RCA thermal degradation products 98 training and law enforcement 278 and use of RCAs 278 training exercises - state advisories and promulgations 278 1,1,1 -trichloroethane acute toxicity 108-9 developmental/reproductive effects 109 disposition and metabolism 109 repeated-dose toxicity 109 trichloronitromethane see chloropicrin tropilidene (CHT) 8 TRP cation channels 52 trypan blue 163 TSII sec thyroid stimulating hormone uptake and distribution of RCAs 37-9 use-of-force matrix 286 use of RCAs 20-3 V-79 185, 187, 189, 191 VAN see nonivamide vanilloid receptor 52, 126, 133, 192 vanilloid receptor-like proteins 52, 126, 133 vehicle see carriers/solvents vesication see blistering Vietnam 231 visible and occult markers 234 volatile organic compounds (VOCs) 306-7, 309, 310 vomiting agents 6 wcight-of-evidencc 262 whole animal genotoxicity assays 186 worker exposure see occupational exposure to RCAs worker protection 278-9 workplace exposure guideline 279 World War I 17 xenobiotic conjugation pathways 42-3 xenobiotic metabolism 39 xenobiotics pulmonary effects 88 xylyl bromide (t-stoff) 5 zinc chloride smoke 234 zinc oxide/hexachloroethane smoke 234

• 353

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