Forensic Diatomology and Drowning

FORENSIC DIATOMOLOGY AND DROWNING MICHAEL S. POLLANEN Department of Chemistry and the Forensic Science Prog;r...

Author: M. S. Pollanen

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FORENSIC

DIATOMOLOGY

AND

DROWNING

MICHAEL S. POLLANEN Department of Chemistry and

the Forensic Science Prog;ram,

Univ ersity of Toronto, Toronto, Canada

Consulting Scientist, Office of the Chief Coroner

Ontario, Canada

1998

ELSEVIER Amsterdam - Lausanne - New York - Oxford - Shannon - Singapore - Tokyo

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.~

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Preface

Odysseus bent his knees and sturdy arms, exhausted by his struggle with the sea. All his flesh was swollen and streams of brine gushed from his mouth and nostrils. Winded and speechless he lay there too weak to stir, overwhelmed by his terrible fatigue.

- The Odyessey, Calypso (Book V) Homer

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The postmortem analysis of drowning is a classical problem in the pathol ogy of sudden violent death, From a historical perspective, one of the most important issues in the study of drowning has been the search for a sensitive, specific, and easily applicable test for this cause of death. On this basis, the diatom test has emerged as the foremost laboratory proce dure for the detection of drowning. Although the history of the diatom test spans a century, no comprehensive monograph has been published to address the scientific and medicolegal basis of the diatom test. This mono graph is an attempt to fill this void in the English-language literature. The monograph is intended as a guide to forensic diatom analysis useful to the forensic pathologist, scientist, death investigator, criminalist, and police officer. The motivation and axiom for the diatom test are discussed in chapter 1 which also outlines the types of circumstances bodies may be recovered from water. In chapter 2, drowning is considered in the broad er context of rapid anoxial death and the postmortem findings of drowning v

are discussed. The medicolegal value and historical development of the diatom test are reviewed in chapter 3, which prepares the foundation for discussion of the author's research on diatoms and drowning using femoral bone marrow (chapter 4). In chapter 4, the utility and validity of the diatom test is analyzed on a quantitative basis. Chapter 5 describes the laboratory procedures for extraction diatoms from human tissues and pre sents guidelines for interpreting the diatom test in forensic casework. The various investigative applications of the diatom test are presented in chap ter 6, with specific reference to the role of the diatom test in homicidal drowning. The final chapter is a photomicrographic and descriptive guide to the freshwater diatoms that are frequently encountered in drowning cases. This chapter, along with chapter 5, will serve to guide forensic practitioners who are interested in performing forensic diatom analysis. The text is followed by a selected bibiliography which includes references that may not have been cited in the main text. Most of the cases used to develop this monograph are from the Office of the Chief Coroner for Ontario, Canada. I thank the professional and tecnhical staff of the Office of the Chief Coroner for Ontario for sup porting this project, and Drs. 1.T. Cairns and D.A. Chiasson for permission to use case material. Permission to publish the case study in chapter 6 sec tion 7 was kindly provided by the prosecutor of the case Assistant District Attorney E. Nneji of Ulster County, New York. The investigators in the case were Chief Daniel P. Miller, Captain George B. Turner and the Detective Division of the Ulster Police Department. I thank Captain Turner for providing crime scene photographs of this case. I am grateful to Drs. D. Noel McAuliffe, Helier 1. Robinson, and Raoul A. Robinson for reading an earlier version of the manuscript and clarifying ideas. I acknowledge Dr. R. Russell for providing access to the diatom collection of the National Museum of Natural History, Smithsonian Institution, Washington, D.C. This project would not have been possible without the dedication of the late Dr. 1. Hillsdon-Smith (former provincial forensic pathologist and forensic diatomist). It is to him that this monograph is dedicated.

vi

ment of the

Contents -;:: descriptive guide ~ ered in drowning . :-' i: ro guide forensic - I diatom analysis. -~ includes references - .}graph are from the k the professional -: :'or Ontario for sup n for permission . d' in chapter 6 sec ssistant District ~ in estigators in the ;: B. Turner and the -.:. I thank Captain ase. I am grateful .1 ul A. Robinson for larifying ideas. I :ie diatom collection -:t. onian Institution, " ~s ible without the ;::" rovincial forensic -.1: this monograph is

Preface ....... .. ...................... . ............. .. v

Contents ..... .. ... . ... ... .. .. .. ......... ............. vii

1. Bodies in water and the diatom test for drowning . . . . . . . . . . . . 1

1 Medicolegal investigation of bodies in water .... . ...... 1 2 What are diatoms? ......... .... ............ ... .. . 2

3 The diatom and drowning axiom .................... 3

4 Unnatural deaths and water ........ ... ...... ... .... 8

* * *

*

Accidental and suicidal drowning ... ..... .. . . .......... . 8

Homicidal drowning ... . ...... .... . .. ...... ... ... .... 9

Drowning in the bath ............... . ............... 12

* 5 References ..... ... .. ..... . .. . . .... ........... . 14

2. The forensic pathology of drowning . . ................ . .. 17

1 Pathophysiology of anoxia ........................ 18

*

*2

Mechanisms of anoxia .... . . . . .. .. . . .. . ..... ... . . . .. 18

Anoxic encephalopathy .............................. 19

The types of asphyxia ... ... ....... . .... . .... .. ... 21

Classification of asphyxial deaths . ........ ........ ..... 2]

*3

Pathology of asphyxia and rapid anoxial deaths ..... ... .. . 21

Fluidity of the blood . . ........ . . .......... .......... 26

Pathophysiology of drowning ...................... 26

VII

- - - - - - - - - - - - - -- - - --- - --- - --- - - - -

Forensic Diatomology and Drowning

*4

Pathology of freshwater drowning .................. 28

Introduction ....... ........ .. ........... ........ .. 28

Peri mortem injury and events ........ . ........ . .. . . . . . 29

Water-related alterations .......... ... .... .. .... ... ... 30

Air passages ... ...... .. ... ... . . . ............ ... . .. 30

Lu ngs ....... .. .. . ....... . . .. . .... . .. ......... .. . 32

Pleural effusion .......... .. ... ...... .... ..... ..... 33

Hemorrhage in the petrous temporal bone ..... . .. ...... . . 36

Visce ral organs . . ... . .. . ............ . ... ..... ... . .. 36

* 5 Pink teeth ... .... ........ ..... ... .. ...... .. .... 36

*6

The history of pink teeth ........ ...... ... .. . .. ..... . . 36

The significance of pink teeth ..... ... ........ .. .. ..... 39

Aquatic decomposition ........................... 39

Aquatic taphonomic factors .... ................ ...... 39

Decomposition sequence in freshwater ..... .. . .... ... ... 40

Adipocere ... .............. ....... ...... . ......... 42

* 7 References .. . . .. ... ....... .. .. .. ... .... .. .. . .. 42

3. The medicolegal value of the diatom test for drowning .... ... 47

1 Analytical approaches to drowning ............. . ... . 47

*

Chemical tests for drowning . ............ .. ... ... ... .. 47

Micro-organism tests for drowning .. .. ... ..... . ..... . .. 49

* 2 The so called "War-on-Diatoms" .. .... .... . ........ 49

* 3 A brief history of the diatom test ................... 52

* 4 Are diatoms ubiquitous in tissue? ............ . .. ... . 54

* 5 Research and the diatom test ...................... 57

Experimental models ... ........... ...... ... ... . . .. . 57

Extraction of frustules .................. . .. ..... .. .. 58

Qualitative and quantitative diatom analysis .............. 58

Use of bone marrow ................................ 59

* 6 References ..... . ....... . ....... . ...... .. . ..... 60

4. Validity and utility of the diatom test using bone marrow . ..... 65

1 Utility . .. .. . ... . . . .... ........................ 66

*

Outcome ratios for the diatom test .. . .......... ... ..... 66

Seasonal and monthly variation of diatom test outcome ..... 66

Vlll

Contents

*2

· .. . ....... 28

Validity ..................................... .. 68

Concepts in support of the diatom test .................. 68

· . . ........ 28

... .. . . .... 29

Test outcome correlates with diatom content of water .... ... 70

•... ....... . 30

Frequency of concordance of frustules in

· .. ..... .. . . 30

bone marrow and water ........................... 72

· . . ........ 32

* 3 Sensitivity and specificity ...... ... ............. ... 77

* 4 References .................................... 82

Size and shape of drowning-associated diatoms ........... 76

· .. ........ 33

The diatom test and diagnostic indices .................. 78

· .. .. . . .. .. 36

.•. .. .... .. 36

· ... ....... 36

5. Laboratory procedure for the diatom test ......... ........ . 83

1 Collection of samples ............................ 83

· . . . ... . ... 36

*

· . ...... ... 39

· . . ..... ... 39

· ... ........ 39

· ... . ....... 40

Collection of samples at the scene ........ .... ... . . .. .. 83

Collection of biological samples ... . ............ . ...... 84

*2

•... ... ...... 42

· .. .. ...... 42

Chain of custody ........ . ....... ..... . ..... . .... . . 87

Laboratory method .............................. 87

Overview .... ................ .. ........... . .... .. 87

Materials ........................................ 88

- .... " .. . . . .. 47

... . . ... 47

••.. . ..... 47

*3

· .• _ ... ... 49

*4

· ... ..... · .... ...... · ... .. . . ... •• . . .. ....

49

52

54

57

· .. . . . .... •.. ...... · ... ...... • . .. ......

57

58

58

59

Procedure ............................... ....... .. 89

Laboratory method for inanimate objects . .... ... .. ... 90

Overview ......... . . ...... ..... .. ..... . .......... 90

Procedure ................................. .. ..... 91

Interpretation .. .. ..... .. .............. . ........ 91

Microscopic examination of bone marrow extracts ......... 91

Microscopic features of diatom frustules . .......... . ..... 96

Non-diatomaceous silica .... .................. . ...... 97

Significance of bone marrow diatoms ............. . ..... 98

* 5 Other methods ................................ 100

Electron and atomic force microscopy ................. 100

M olecular biologica l approach to the diatom test ......... 101

... . . . . ... 60

* 6 References .. . . . . ........ . .................... 103

·-::>oW... . .. 65

.... ... . .. 66

6. Investigative applications of the diatom test ............... 105

1 General applications ............................ 105

... .... 66

Indications for the diatom test. ....................... 105

*

Contra-indications for the diatom test ... . .. . ........... 106

lX

_.-

-~,


*2

Decomposition and the diatom test ............... .. 107

Aquatic decomposition and the diatom test ............. . 107

Skeletonized bodies and the diatom test ......... .. ... . . 107

* 3 Drowning in filtered water ................ .. ... . . 108

* 4 Dismembered body parts ..... . ................ .. 108

* 5 Diatoms as trace evidence .............. . . .. . . . . . . 112

* 6 Diatoms and homicide .. ... ............. . .. . .... 113

* 7 Case study: Murder in the Hudson river ...... ...... . 115

* 8 References ... .. ....... . . . ............ . .. .. ... 124

7. A guide to the freshwater diatoms of drowning ........... . 1 Centric diatoms ... . ... . ... . ................... 2 Naviculoid diatoms . . . . .... ... .. .... . ........... 3 Dorsiventral diatoms . . . .. .. .. . .................. 4 Epithemia ... . ..... . . . .... .................... 5 Nitzschia and Hantzschia . ..... . .. ............... 6 Asterionella and Tabellaria . ....... . .............. 7 Cocconeis ....... . .. . ... . ..................... 8 Heteropolar and other diatoms ... .... . ............ 9 Cuneate and other diatoms ... . .. ... . . . . .......... 10 Elongated diatoms . ............................ 11 Small pennate diatoms .. . ... . .. ... ... ... .. .... . .

* * * * * * * * * * *

125

126

128

130

132

134

136

138

140

142

144

146

8. Selected bibliography .. . . . . ... . ..... . . ... .. . . .... ... 149

Author index . . . . . . ...... .. ... . ........ .. .. .. ... .. . ... 155

Subject index .... . . .. .. ..... .. ....... ... ... . ... . . .. . . 157

x

· ... . . . ... 107

•• . . .... 107

•.•. ...... 107

· .... ..... • . . . ..... · .. . . . .... · . . .. . ... • •. . . . ... · ..... ...

108

108

112

113

115

124

· .... . ... · ....... .. .•... . .. · .... . . .. · .. ...... .. . . .... . .. · .. . . . ... · •.. .. . .. · ... ..... · .. . ..... · ... . . ... · ... . . ...

125

126

128

130

132

134

136

138

140

142

144

146

1. Bodies in water al1d the diatom test for drowning

A body recovered from water mayor may not have drowned. This leads to two basic problems: determining both the cause of death and manner of death. Both of these problems are difficult when confronted with a body from water, particularly if decomposition has altered the classical findings associated with drowning or another cause of death. In this chapter, the cir cumstances of death associated with water are introduced and the concep tual foundation of the diatom test for drowning is described. Although the diatom test may not, in most cases, contribute to understanding the man ner of death there is a role for the test in determining the cause of death in cases of bona fide drowning.

· ... . .... 149

· .•. . . .... 155

* 1. MEDICOLEGAL INVESTIGATION OF BODIES IN WATER

· ..... .... 157

Drowning is distinguished from many other violent causes of death since the pathology of drowning does not correlate with the manner of death. Unlike manual strangulation, multiple gunshot wounds, and multiple blows to the head, which are almost always homicidal, the postmortem findings in homidical and accidental drowning are indistinguishable. This matter is further complicated by considering the more general case of a dead body recovered from water. In principle, a body recovered from water need not have died in the water, and drowning may not be the cause

-

- - - - -.f.

---.

- -

_ __

--

---


of death even if the death occurred in water (1). Therefore, the medicole gal investigation of a body recovered from water must consider the fo l lowing special questions: 1. Did death occur by drowning? Did drowning occur at the site of body recovery? 2. Did death occur by means other than drowning while in the water? 3. Was the body immersed in the water postmortem ? 4. Is the death due to a criminal act? All of these unique issues relate to the pathology of drowning and can, at least in part, be addressed by full postmortem examination. However, since the lesions of drowning are variable (chapter 2) there is an important role for ancillary tests for drowning include laboratory based analyses using tiss ues recovered at postmortem examination. The most important of these tests is the diatom test for drowning.

* 2. WHAT ARE DIATOMS? Diatoms are aquatic unicellular plants that represent a major taxonomic division of the phytoplankton (2, 3). The most dis tinctive feature of this unicellular organism is its extracellular coat or frustule, which is com posed of silica. The frustule of the diatom is a crystalline structure that is characterized by unique patterns of synunetry and microstructure. On this basis, the vast structural diversity of the frustule leads to a remarkable number of morphologically-distinctive varieties of diatoms. This vast degree of morphological variation gives rise to a large number of species. Recent estimates indicate that there are in excess of 10,000 different species of diatoms. Diatoms are most often encountered in naturally occurring bodies of water such as lakes, rivers, oceans, seas, ditches, and puddles. Some diatom species have preference for water of specific salin ity thus allowing general distinction between freshwater and marine diatom types . In addition, some diatom species are more frequently asso ciated with soil and puddles than lakes. Fossilized diatoms are another major source of frustules in the biosphere, although, these frus tules are derived from long dead diatoms. Such diatoms are mined for commercial 2

-

Bodies in Water

_ :_e medicole - ..:le _ the fol-

use and maybe as forensically important as live freshwater contemporary diatoms. Mined fossilized diatoms are used in several commercial prod ucts including the fine abrasives in polishing compounds (4). One seldom emphasized feature of diatoms are their complex pop ulation dynamics and ecology. Diatom populations are constantly in fl ux and these fl uxes are the result of complex and poorly understood nu trient and aquatic cycles. The net res ult of these environmental variations is a monthly periodicity in the abundance of live aqu atic diatoms with blooms of diatom populations in the spring and autu mn (i.e. seasonal maxima) (5). In addition, there are temporal and spatial variations in diatom concentra tion in any body of water in response to local factors includi ng mineral content of water, temperature, water stratification, and acidity. A poorly understood aspect of diatom ecology is the variation in the species and genus distribution over seasons. These ecological characteristics of diatom populations have great, and under utilized, forensic significance. Among 11 the most important forensically relevant feature of diatom populations is the monthly variation in water concentration of diatom frustules that should, a priori, effect the outcome of the diatom test for drowning during vario us times of the year. The widespread distribution of diatoms in water and their morphological specificity makes the diatom an important foren sic marker of drowning.

-.:: _~e of body - ~.e water?

. ning and .1lJlinarion. :ilere is an " 1)' based :. The most

._'w norruc

* 3. THE DIATOM AND DROWNING AXIOM

- __: ~ :e . On this .: _ remarkable - ~ -. This vast _ _ _ !" of species. .. . ~ 00 different ;;~:: ~ in naturally . di tches, and - ~ ~ -pecific salin ..:.:~ r and marine :':equently asso .-: _::: are another -'?:_f: frustules are -:'L ~-or commercial

The conceptual foundation of the diatom test for drowning is illustrated in fi gure 1.1. In the drowning process, water is inhaled and distends the alve oli. The diatoms that are present in the drowning medium perforate the alveolar-capillary barrier (Fig. 1.2 & 1.3) and enter the pulmonary venous circulation (6). Once the diatom-laden blood is returned to the left side of the heart, the diatoms embolize to organs and tissues such as the bone mar row. Therefore, the presence of diatoms in the femoral bone marrow is an indication of antemortem inhalation of water. If diatoms are detected in the bone marrow (a positive test) this implies that: 1. Drowning caused death or was a contributing factor to death 2. The individual was breathing upon entry into the water. 3

-

--

.---'

Forensic Diatomo[ogy and Drowning

LIVE ENTRY

T~~

DUMPING

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l

COMPARE TYPES

PERCOLATION

rn

t!J

DISSEMINATIO N

1.1. The conceptual foundation of the diatom test for drowning using femoral bone marrow as the source to extract diatoms . If a dead body is immersed in water, diatoms may percolate into the lungs but cannot disseminate in the circu latory system. (Modified from Bernard Knight, Legal Aspects of Medical Practice, Churchill Livingston Publishers, 1972. Illustration by Jackie Robers).

4

a c

211

_::lg using femoral :- ' _ i immersed in '- te in the circu - ~_ I of Medical Ja b e Robers).

1.2. Diatom (Diatoma moniltformis) penetrating the wall of a distal airway in an experimental rodent model of drowning (Scanning electron microscopy, 6,000 X). Courtesy of Dr. Phillippe Lunetta, Department of Forensic Medicine, University of Helsinki. 1.3. Two diatoms (Phaeodactylum tricornutum) found in the lumen of an alveo lar capillary in an experimental rodent model of drowning (a = alveolus, i = inter stitium , c = capillary lumen, d = diatom) (Transmission electron microscopy, 6,600 X). Courtesy of Dr. Phillippe Lunetta, Department of Forensic Medicine, University of Helsinki .

5


If a dead body is placed in water, diatoms may passively enter the tra cheobronchial tree and the alveoli by percolation (7). However, since the heart is not beating, diatoms cannot be dissemeniated to peripheral tissues. The silica-based frustule of the diatom allows for the easy extraction of diatoms from human tissues by digestion of tissues in agents such as strong acids. Although other methods for diatom extraction have been advocated, the acid digestion method and centrifugation has been the most consistently applied and gives highly reproducible results. Various tissues have been used as starting material for the extraction of diatom frus tules. Bone marrow removed from a femur is a popular choice. The advantage of the bone marrow extracted from an intact femur is that contamination can be minimized or eliminated since the marrow is extracted from a "closed" organ that can not be soiled by diatoms from some external source. For the test to be considered valid it is necessary, in most instances, to prove the origin of the diatoms by showing that the types of diatoms extracted from the bone marTOW are concordant with those in the drowning medium. This is accomplished by simple morphological comparison of taxa in the bone marrow and a sample of water from the site of drowning (Fig. 1.4). The forensic pathology community has been, historically, polar ized in its general acceptance of the diatom test as a definitive diagnostic test for drowning. The practical result of this polarization is that the medicolegal community in the United Kingdom, Japan, Europe, and South America (e.g. Uruguay) apply the test with greater frequency than in North America and elsewhere in the world. This is in part due to the origin of the test in continental Europe and because much of the research on the test is derived from laboratories on the continent. One of the main events in the historical debate on the diatom test was the demonstration, by some investigators, that diatoms may be present in the extracts of tissue prepared from non-drowned people. These inves tigators concluded that this finding limited the medicolegal utility of the test. However, this criticism of the diatom test has been successfully met by using the "criterion of concordance" which demands that the diatoms recovered from tissue be comparable to the diatoms in the putative drown ing medium (8, 9). This criterion makes the origin of the diatoms unam biguous and proves the diatoms originated from the drowning process and not some other non-relevant mechanism. 6

Bodies in Water ~='er

the tra

River

"";;;._i.U

e _iagnostic that the nd Sou th Femur

1.4. Concordant freshwater diatoms [Stauroneis sp. (left set), and Asterionella formosa (right set)] extracted from the femoral bone marrow in a case of drown ing and the water in which drowning occurred.

7


* 4. UNNATURAL DEATHS AND WATER Dead bodies that are found in water may have died in water or may have been relocated into a watery environment. Bodies in water are recongized to fall into four major categories: 1. Accidental and suicidal drowning. 2. Homicidal drowning. 3. The body intentionally placed in water posmortem ("the dumped

body").

4. Drowned bodies moved from the water.

Accidental and Suicidal Drowning Accidental drowning in open water during the Summer months accounts for the majority of all water-related deaths. The circumstances of acciden tal drowning are highly variable but commonly occur as follows: 1. Drowning de novo usually associated with water-related recreational

activity.

2. Drowning complicating natural disease (e.g. atherosclerotic coronary

artery disease).

3. Drowning complicating acute ethanol intoxication or other drug

intoxication.

Many victims of accidental drowning are intoxicated and this is an impor tant contributing factor in several water-related fatalities. The ability to swim is not an impOltant correlate of drowning since most victims of drowning are able to swim. Accidental drowning may also occur in mass disasters such as ferry accidents, and plane crashes. The role of hypother mia must be carefully evaluated in many cases of apparent drowning. Hypothermia may be a contributing factor or sole cause of death in some cases. A rare variant of accidental drowning is "micturation syncope" were a recreational boater may collapse unconscious into the water while uri nating over the edge of the boat. Suicidal drowning (10, 11) is infrequent and usually occurs in indi viduals with well a documented psychiatric history. Frequently, suicidal 8

Bodies in Water

_:er or may have re recongized

~£:-

drowning will occur after discharge from a mental health facility or short ly after a psychiatric consultation. In exceptional circumstances, suicidal drowning may be the first manifestation of acute paranoia. Some victims of suicidal drowning will disrobe prior to entry into the water or will weigh themselves with down with stones or other heavy objects.

Homicidal Drowning mped

:::

accounts :_-:: - of acciden ~,-llows:

--=_.-:=- :-e reational

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victims of cur in mass -=- =-,-1:e of hypother - _:,;,are nt drowning. ... .::. ~ f death in some ~- _ :__ _ -~ncope" were -=-.\' rer while uri _ ~-",,:_. occurs in indi :: ~= .; ently, suicidal

Sir Sydney Smith reported that 5% of all drownings, in his experience in Egypt, were homicidal. This figure is consistent with experience in North America and underscores the need for careful consideration of the manner of death of all bodies found in water (12). In most cases of homicidal drowning, postmortem examination reveals other violent injuries, most commonly blunt force injuries of the head, or strangu lation. In such cases, drowning is usually a terminal event complicat ing the other inuries. However, homicidal drowning in the absence of other injuries can also occur and has many contexts . The most widely appreciated is the famous Brides in the Bath case . In December 1914, Margaret Loftus was drowned by her hus band, who called himself John Smith, while bathing (13 ) . Initial investigation led to a verdict of accidental drowning and the husbad collected an insurance settlement. S ubseq uent investigation revealed that several previous wives of Mr. Smith also died of drowning. The previous investigations suggested that the drownings were due to acci dent or the consequence of epilepsy. Smith was later convicted of murder and executed. The Brides in the Bath case illustrates difficul ties of assigning a manner of death in drowning. Determining if open water drowning is homidical may be con siderably difficult and often relies on careful postmortem examination to reveal injuries of assault or pressure on the neck. In addition, scene findings often provide important evidence for assigning manner of death, even if the scene is a deep lake. Bodies may be recovered with weights attached (14), or objects used to weigh down the body may be found at the bottom of the body of water if it becomes detached from the corpse (Fig . 1.5 & 1.6).

9


1.5. Body recovered from a lake with rope attached to the belt-loops of the pants. A knot was found at the other end of the rope that was free-floating in the water. Autopsy revealed drowning , recent pressure on the neck, and diatoms were recov ered from the femoral bone marrow. (Photograph by Cst. R. S. MacLeod).

1.6. A patio stone found at the bottom of the lake near the site the body depict ed in figure 1.5 was recovered. The assailant rendered the decedent unconscious by throttling and drowned her by weighing her body down with the patio stone. (Photograph by Cst. R. Stiver).

10

Bodies in Water

1.7. Scalding injuries from bath water with subsequent drowning in the bathtub. This type of domestic drowning death is most often seen in the elderly with ath erosclerotic heart disease. 1.8. Old contrecoup contusions of the inferior frontal and inferior temporal lobes in a case of drowning in the bathtub. Old contusions may be epileptiform sites that led to a grand mal seizure disorder. Accidental drowning in bathtubs, and pools can occur as a complication of a seizure. (Photograph courtesy of Dr. J.R.N . Deck)

_=- . :.2~nI nconscious e patio stone.

.' 11

--1.

-

- -- -


Drowning in the Bath Drowning in domestic water, such as in the bathtub, accounts for a large subset of immersion deaths (15, 16). Unlike open water drowning, the cir cumstances that are often associated with drowning in the bathtub are more limited and usually fall one of the following categories:

1. Accidental drowning complicating natural disease (e.g. coronary

artery disease, or epilepsy)

2. Accidental drowning complicating drug intoxication. 3. Homicidal drowning (e.g. Brides in the Bath) 4. Suicidal drowning (e.g. the frail elderly or infirm) The most common circumstance is accidental drowning that complicates acute collapse (e.g. grand mal seizure or cardiac arrythmia) due to natural disease. In the case of atherosclerotic heart disease, acute cardiac arryth mia may occur while preparing the bath and peri mortem scalding may occur when the skin is exposed to the hot water (Fig. 1.7). In these cases, significant hyperemia may be found in pharynx and air passages indicat ing aspiration of hot water and thermal injury to the mucosa. Features of drowning are usually, but, not always apparent. In the case of the latter, death may be related more to immersion and intercurrent natural disease than true "wet-drowning". An important preventable type of domestic drowning is drowning complicating an epileptic seizure (17) . In most cases, a clinical history of epilepy in known or anti-epileptic medication can be found at the scene. Several important observations can be made at the time of post mortem examination that may indicate an epileptic seizure-associated drowning including blunt injuries to the tongue (due to biting), and stig mata of the chronic use of phenytoin including gingival hypertrophy, cerebellar atrophy, hepatomegaly, and rarely interfollicular hyperplasia of lymph nodes. In a minority of cases, examination of the brain may reveal structural lesions to account for the seizure disorder. The most common lesion is remote contrecoup contusion of frontal and/or tempo ral lobes (Fig. 1.8). Other focal lesions that may be found infrequently include hippocampal sclerosis, polymicrogyri, neuronal heterotopias and gliomas. 12

Bodies in Water

One important variant of domestic drowning is spontaneous birth into the toilet (18) and infanticide by drowning of the newborn. These cases produce considerable practical difficulties since it is necessary to establish live birth. In the case of spontaneous birth into the toilet, the mother is often primiparious and has denied pregnancy until the time of birth. In principle, the diatom test for drowning can be valuable in estab lishing live birth; however, since domestic water usually lacks diatoms, positive test outcome are infrequent «10%).

The Concealed or Dumped Body

= .:

~omplicates

- _ ral disease

- =:- drowning _ ,: . ·n · al history

-

~=

:'o und at the of post _ . ::":' _ ~e - ssociated . : :- . :.:.~g ) . and stig ~ - =_ :... nypertrophy, . ~ __ 3.[ hyperplasia _ .:. :- _ e brain may _ - ~ :-je r. The most - _- :, and/or tempo infrequently =-=-. :-.e .e otopias and _

--::- - ''"TI e

. :.:. -= "

Recovery of a body in water does not imply drowning. In some cases of accidental drug intoxication (e.g. heroin) the body in maybe concealed in water at some distance from the site of death by witnesses of the death that may also using drugs in a "shooting gallery". Homicide by means other than drowning followed by concealing the body in water also occurs. The corpse may be weighed down (see chapter 2, Fig. 2.26) to hamper efforts to locate the body. In the case of the dumped homicide victim or drug overdose, postmortem examination and toxicological studies are usually sufficient to establish a cause of death, unless the mechanism is asphyxi al. In a study of homicide victims disposed of in lakes of Missouri, U.S.A., Dix (14) found that all cases were weighed down with concrete blocks, barbell weights, wheels, or anchors. In all cases, significant aquat ic decomposition had occurred over the elapsed time since death and dis covery (4-10 months).

Drowning Deaths Moved from Water A small proportion of water-related deaths may be found remote of the water such that the scene does not imply drowning as a cause of death. Such circumstances, although rare, need to be considered particularly since cases of homicidal drowning may be moved to land and may be fur ther concealed by decomposition in an isolated location or burned post mortem. Some cases of accidental drowning in the bath may be removed to the bed to suggest a natural cause of death. 13


Findings at postmortem examination may not be interpreted as drowning if the body is not recovered from water. However, the presence florid oedema of the lungs in the absence of congestive heart failure, and watery fluid in the stomach and sphenoid sinus maybe important indica tors of drowning in this circumstance. The diatom test for drowning may play an important role in determining the cause of death in concealed homicidal drowning. Therefore, some forensic pathologists will routinely harvest a femur for diatom studies in all cases of this type, even if the post mortem findings of drowning are not apparent at autopsy.

* 5. REFERENCES 1. Davis JR. Bodies found in water. American Journal of Forensic Medicine and Pathology 1986;7:291-297. 2. Round FE Crawford, R.M., Mann, D.G. The Diatoms: Biology, and morphology of the genera. Cambridge University Press, 1990 3. Cox EJ. Identification of freshwater diatoms from live material.New York: Chapman and Hall, 1996 4. Peabody AJ. Diatoms in Forensic Science. Journal of the Forensic Science Society 1977; 17: 81-87. 5. Hendey NI. The diagnostic value of diatoms in cases of drowning. Medicine, Science, and the Law 1973;l3(1):23-34. 6. Lunetta P Penttila, A. Scanning and transmission electron microscop ic evidence of the capacity of diatoms to penetrate the alveolar-capil lary barrier in drowning. International Journal of Legal Medicine 1998;in press. 7. Taylor n. Diatoms and drowning -- a cautionary case note. Med Sci Law 1994;34(1):78-79. 8. Timperman 1. Medico-legal problems in death by drowning: Its diag nosis by the diatom method. Journal of Forensic Medicine 1969; 16(2):45-75. 9. Hendey NI. Letter to the Editor, Diatoms and Drowning - A Review. Medicine, Science, and the Law 1980;20(4):289. 10. Copeland AR. Suicide by drowning. American Journal of Forensic Medicine and Pathology 1987;8: 18-22. 11. Auer A. Suicide by drowning in Uusima province in southern Finland. 14

Bodies in Water

::1terpreted as

=- . ~.. I1ant indica _ .

.

rung may .. : ~ :::h in concealed ~= will routinely -: ~ ::\"en if the post -:

. .:: ::

[0\\

-T

_

~=5 :

Biology, and

Med Sci Law. 1990;30(2):l75-l79. 12. Copeland AR. Homicidal Drowning. Forensic Science International 1986;31 :247-252. 13. Kerr DJA. Asphyxia. In: Forensic Medicine. Sixth ed. London: Adam and Charles Black, 1957: 157-158. 14. Dix JD. Missouri's lakes and the disposal of homicide victims. J Forensic Sciences 1987;32(3):806-809. 15. Devos C Timperman, J., Piette, M. Deaths in the bath. Medicine, Science, and the Law 1985;25: 189-200. 16. Schmidt P Madea, B. Death in the bathtub involving children. Forensic Science International 1995;72: 147-155. 17. Ryan CA. Drowning deaths in people with epilepsy. Canadian Medical Association Journal 1993;148:781-784. 18. Mitchell EK Davis, J.H. Spontaneous births in toilets. Journal of Forensic Sciences 1984;29(2):591-596 .

. . e- -. 1990

- - note. Med Sci

ning - A Review.

15

2. Forensic pathology of drowning

Drowning is a member of a general class of sudden violent death due to the rapid exclusion of oxygen from mitochondrial oxidative phosphoryla tion. This class of violent death is known as the rapid anoxias and encom pass several distinct physical and biochemical modes of inhibiting oxygen entry, transport and utilization by the body. The rapid anoxial deaths have traditionally represented the most difficult of all deaths encountered by the forensic pathologist for many reasons including: 1. The lack of pathognomonic postmortem findings in rapid anoxial

death.

2. Widespread misconceptions regarding the sensitivity and specificity of the classical postmortem findings associated with rapid anoxia. 3. The numerous mechanisms that can ultimately lead to acute anoxia are diverse and many are not associated clear associated with post mortem lesions (e.g., suffocation of an unconscious indiviudal or one incapable of defense). While drowning is considered a rapid anoxial process due to obstruction of the airway with inhaled fluid, numerous other biochemical 17


alterations occur simultaneouly due to hemodilution. On this basis, drown ing is anoxial but associated with acute electrolyte changes. However, many of the pathophysiological process and postmortem findings associ ated with drowning may be observed in the other rapid anoxial processes since the final common pathway to death is similar.

* 1. PATHO PHYSIOLOGY OF ANOXIA Mechanisms of Anoxia

All acute anoxial processes ultimately lead to a deficiency in molecular oxygen flow to aerobic metabolism. The four distinct mechanisms that leads to this oxygen depleted state are: 1. Anoxic anoxia which occurs due to the reduction of oxygen passage through the alveolar-capillary barrier leading to decreased oxygen saturation of hemoglobin (e.g., obstruction of any level of the respira tory system). 2. Anemic anoxia which occurs due to a reduction in the amount of hemoglobin able to carrier oxygen in the erythrocyte (e.g., carbon monoxide displaces oxygen from hemoglobin). 3. Ischemic anoxia due to the inability to delivery oxyhemoglobin to the brain due to reduced arterial perfusion (e.g., sudden carotid occlusion or acute cardiac arrthymia). 4. Histotoxic anoxia due to chemical uncoupling of the electron trans port chain (e.g., cyanide ion binding to mitochondrial cytochrome subunits and inhibiting the flow electrons used for energy produc tion). The anemic and histotoxic anoxias are sometimes collectively referred to as the chemical anoxias since both mechanism require an exo geneous toxin. Similarly, anoxic and ischemic anoxia are due to mechani cal forces and, in many circumstances, both anoxic and ischemic mecha nisms are coupled as in strangulation with compression of the airway and the neck vasculature. The net result of any rapid anoxial process is cere bral anoxia which ultimately leads to ventricular asystole or fibrillation. 18

Pathology of Drowning

:-.: basis , drown ~ .::-.g s. However, - ~ -= ::":1dings associ - ;: -c 0xial processes .3

-

=- ~. :n molecular '. Te banisms that ::: _.>::'ge n passage _. c" 'ed oxygen _~ e ~ of the respira - 3ffiount of ~

e . .~ carbon

-.=r::.o _lobin to the ;;- : ?--a:id occlusion

-.: electron trans _ ...;,~ ~y tochrome . .. ;: -Lergy produc

'"":"':':"''Ues collectively _rn require an exo _ .:.Ie due to mechani - :1 i chemic mecha . -- of [he airway and - _. _.....: process is cere :t::'.e or fibrillation.

Anoxic Encephalopathy

The main pathophysiological consequence of any rapid anoxial process is cerebral anoxia. The morphological correlates of cerebral anoxia are mainly related to the duration of the anoxic insult and the interval of survival after the insult. Thus, in rapid anoxial deaths, no structural alteration can be found in the brain in most cases. However, if there is a limited survival interval (e.g., in hospital after resuscitation) after the anoxic insult subtle changes can be observed in the brain. The distribu tion and types of cellular change found related to the length of the sur vival interval such that a minimum of 4-6 hours is required to demon strate unequivocal cellular features of anoxia. The earliest indicator of cerebral anoxia in selective neuronal necrosis in areas of the brain that are preferentially vulnerable to reduced oxygen tension. These areas include the pyramidal neurons of the cerebral cortex, and Ammon's horn (Sommer's sector). Early neu ronal necrosis is typified by nuclear hyperchromasia and pyknosis and the perikaryon is shrunken and eosinophilic (Fig. 2.1). Oedema of the neuropil often accompanies the earliest evidence of neuronal lysis. Purkinje cells of the cerebellum may show early evidence of neuronal necrosis but may appear uninjured even when hippocampal neuronal necrosis is well developed. As the survival interval lengthens, the appearance of neuronal necrosis appears more widespread and this is accompanied by generalized cerebral swelling and herniation mass effects due to cerebral oedema. Although all neuronal populations ulti mately show features of necrosis, the neurons of the basis pontis, and the cranial nerve nuclei may appear resistant after many hours of sur vival in the brain dead state. The aftermath of selective neuronal necrosis of the cerebral cor tex is a conspicuous pattern of laminar necrosis (Fig. 2.2). This corre sponds to local phagocytosis of the necrotic pyramidal cell layer, and often adjacent neuronal laminae, and may show microscopic evidence of astrogliosis and capillary proliferation. Laminar necrosis of the neo cortex is observed only after a prolonged survival interval, usually of several weeks, if somatic death does not occur in the period of maximal cerebral swelling. 19


2.1. Necrotic neurons with pyknotic nuclei and oedema of the neuropil in hypox ic cerebral injury. Neuronal necrosis and oedema are the earliest microscopic lesions of cerebral anoxia and take hours to develop. No microscopic changes in the brain are found in rapid anoxial death. (Hematoxylin-eosin, 400 X) 2.2. Laminar necrosis of the cerebral cortex in a case of throttling with a survival interval of several weeks in hospital. The zonal loss of selectively vulnerable cor tical neurons gives a well demarcated line of necrosis .

20


* 2. THE TYPES OF ASPHYXIA Classification of Asphyxial Deaths

Asphyxial deaths represent a specific subset of the rapid anoxias and are defined as deaths due either to anoxic anoxia or ischemic anoxia or a com bination of the two mechanisms. The main categories of asphyxia are clas sified, thus: 1. Suffocation due either to obstruction of the mouth and/or nares, or

inhalation of oxygen-deficient gas.

2. Choking due to physical obstruction of the airway. 3. Pressure on the neck due to manual or ligature strangulation, hanging, or other modes of neck compression. 4. Positional asphyxia due to restriction of chest expansion during ven

tialtion. This includes asphyxia of restraint and traumatic or crush

asphyxia.

5. Drowning. Pathology of Asphyxia and Rapid Anoxial Death

The lesions of asphyxia and rapid anoxia can be divided into three types of pathological changes : 1. Local physical injuries. 2. Lesions related to increased venous pressure. 3. The signs of rapid anoxial death (the "soft signs" of asphyxia).

:: :".::- j e. t microscopic _. .: opic changes in ' - ~ L -lOa X) -- : " ~D g

with a survival

-. dy \'ulnerable cor-

The local physical injuries, if present, are usually associated with the mechanical effects of producing the anoxic insult. The injuries in the later category are violent and usually relate to pressure on the neck, or suffoca tion. The paradigm violent asphyxial process is manual strangulation (1-3) that can be used to survey the lesions of asphyxia and pressure on the neck (Fig. 2.3-2.13). Manual pressure on the neck may produce superficial abrasion and/or contusion to the ventral aspect of the neck (Fig. 2.3). These superficial injuries can range from absent or minimal to florid, par ticularly if the victim's clothing is caught by the strangling hands and 21


2.3-2.6. The Pathology of Manual Strangulation. 2.3 Multiple punctate abra sions of the ventral neck. 2.4. Fresh bruising of the strap muscles. 2.5 Submucosal laryngeal hemorrhages. 2.6 Bilaterally symmetric fractures of the greater horns of the hyoid bone.

22


: .Jhiple punctate abra "rrap muscles. 2.5 ccri fractures of the

• Z.9

2.7-2.10. Occult Laryngeal Injury in Strangulation. 2.7 & 2.S. Parasagittal sec tions of the superior cornu and associated cartilages of the larynx from a 21-year old female victim of manual strangulation (right) and a control case of a 21-year old female victim of an accidental heroin intoxication (left). There is focal hem orrhage (arrows) within the cartilage of the superior cornu in the victim of man ual strangulation. 2.9. Acute perivascular hemorrhage in the laryngeal cartilage. 2.10. Acute microfracture of the laryngeal cartilage. 23


abrade the skin. Curvilinear abrasions may be present indicating fingernail marks, and rarely, digital pad pressure (mostly from a thumb) can lead to punctate contusions. Hemorrhage may occur in the soft tissues of the neck including the subcutis and platysema, strap muscles (mostly the ster nomastoid and stenohyoid), and about the carotid sheath (Fig. 2.4). Horizontal tears of the carotid artery intima may be found due to carotid manipulation and stretching. Due to the exposed location, the hyoid bone and larynx are sus ceptible to a range of injuries. Among these injuries is fracture which can be determined to be antemortem in the fresh body by the presence of adja cent hemorrhage. In some cases of manual strangulation, the hyoid bone will be symmetrically fractured and in other cases, one horn will be frac tured, usually on the side of the neck with maximal soft tissue injury. A remarkable range of local and remote indirect hemorrhages occur due to pressure on the neck. The mechanisms of these hemorrhages were investigated by Camps & Hunt in their landmark paper (1) "Pressure on the Neck". Pressure of the neck leads to two main types of indirect hemorrhages: local submucosal hemorrhages in the larynx (Fig. 2.5), pos terior pharynx, and pyriform sinuses; and remote petechieal hemorrhages of the cheeks, eyelids, conjunctivae, and serosal surfaces of the lungs and heart (Fig. 2.11-2.13). Local submucosal hemorrhages of the neck organs are perivenous and due to occlusion and rupture of the delicate laryn geopharyngeal venous plexus during strangulation. Petechieal hemor rhages of the conjunctivae, likely relate to increased jugular venous pres sure and subsequent rupture of the capillary bed. However, direct anoxia and release of endogenous mediators are also a possible contributing fac tor (4). The classical site of fracture to the larynx is the superior cornuae of the thyroid . cartilage. T his pattern of fracture is most commonly observed in manual strangulation and may be found in pressure of the neck from a carotid sleeper hold. Many victims of strangulation are you ng females with laryngeal cartilages that are not calcified and are, therefore, pliable and deformable in the process of manual strangulation. This leads to intracartilaginous laryngeal hemorrhages that the same location in the superior cornuae as fracture in older victims of strangulation (Fig. 2.7 2.10). Gross examination of the base of the superior cornuae may often 24

Pathology of Drowning _~ _

_

::ng fingernail can lead to

__""": I

- . .> :-tyoid bone

_:;: .\ ill be frac .: e lOJury. _ - -: ' emorrhages .>-e'hemorrhages - _- -:- ( 1) "Pressure _: ;-es of indirect - _ Fig. 2.5), pos hemorrhages _ -=- , :' [be lungs and o

~

2.11-2.13. Petechial hemorrhages in Asphyxia. 2.11. Eyelid. 2.12. Conjunctiva. 2.13. Epicardium.

_; __" venous pres =- '~:-. direct anoxia , : ontributing fac • :: :Jperior cornuae :n t commonly :'. --ure of the neck

~.e

location in the ; , rion (Fig. 2.7 - : ::mae may often 25


show acute hemorrhage upon sectioning. Microscopic examination con firms the presence of acute perivascular hemorrhage that dissects between collagen fibres in the chrondroid matrix. Feature of strangulation or compression of the neck may be found in many cases of homicidal drowning. In cases of this type, drowning may occur after neck compression and death may due to the combined asphyx ial effects of drowning and strangulation.

Fluidity of the Blood Rapid anoxial death, such as strangulation and drowning, is often associ ated with a highly reproducible but poorly understood series of non-spe cific postmortem findings. These include postmortem fluidity of the blood, perimortem urinary and/or fecal incontinence, and in the decomposed body, the presence of controversial pink teeth. Persistent fluidity of the blood likely relates to inhibition of the coagulation process due to some unknown mechanism. Initial studies on the biochemical basis of the persistent fluidity of postmortem blood in rapid anoxia revealed endogeneous fibrinolysin aci tivity (5, 6). This has led to the proposal that the blood rapidly clots post mortem, and the fibrin is subsequently lysed producing fluid blood. However, using Western blotting for the detection of fibrinogen in the fluid blood of vicitms of drowning and strangulation, we have found that the fibrinogen is the blood is not depleted (Pollanen & Boyle, unpublished observations). This indicates that the persistent fluidity of asphyxial blood is due to failure of the blood to coagulate rather than the lysis of clotted blood.

* 3. PATHOPHYSIOLOGY OF DROWNING The physiological consequences of the inhalation of water have been stud ied in animal models (dogs, sheeps, and rabbits) of drowning and using meta-analysis of reports of drowning and near-drowning in humans (7). The physiological changes in drowning can be addressed in four major areas: 1. Blood gases and acid-base changes. 2. Ventilatory effects. 26


oination con ts between

_ . _. Crowning may - ~ c~b ined asphyx

- :: brinolysin aci _ __ idly clots post __': :'1g fluid blood. - : ..ugen in the fluid 'e found that the o--:.le, unpublished •. phyxial blood ~e lysis of clotted

NG ,:-;?!' have been stud ___ wning and using :- -::g in humans (7). ':: _ d ·in four major

3. Changes in blood volume. 4. Changes in serum electrolytes. Experimental studies indicate that the lethal physiological changes in drowning is anoxia due to airway obstruction. Although some investiga tors have emphasized rapid alteration in serum electrolytes, this effect seems less important since profound disregualation in ion homeostasis is not an important feature of cases of near-drowning with a survival in hos pital. Analysis of oxygen tension in experimental models of drowning and near-drowning indicate that arterial hypoxemia (oxygen content and hemoglobin saturation) is the most rapid and physiologically important change after the air passages fill with water. In several different species (man, dog, sheep, and rabbits), profound changes in oxygen tension occur with inhalation of 1-3 mLlkg (7) . Hypercapnia occurs simultaneously and may lead to hyperventilation if the anoxia does not lead to a rapid anoxial death. Both metabolic and respiratory acidosis occur with the respiratory element predominating early and metabolic acidosis occuring with a sur vival interval. The principal intra-pulmonary consequences of drowning, which ultimately lead to hypoxemia, are airway obstruction and intrapulmonary shunting (V/Q mismatch) due to perfusion of non-ventilated parenchyma. This has been likened to a "space occupying lesion in the alveoli ". If sur vival occurs in a near-drowning, there may be delayed lung injury (e.g., diffuse alveolar injury, and bacterial pneumonia) that further comprimises lung function and can lead to ongoing respiratory acidosis, hypoxemia, and delayed death due to respiratory failure and sepsis. Massive and rapid shifts may occur in blood volume due the inhalation of a fluid medium into the alveoli since there is a highly per meable barrier between the alveolus and the capillary. Such shift in vol ume status can be monitored by alterations in otherwise stable electrolyte concentrations. In the case of freshwater drowning there is an increase in the systemic blood volume due to the influx of a hypotonic fluid (8). Similarly, in saltwater drowning there is an decrease in the systemic blood volume due to the influx of a hypertonic fluid. Such shifts can be moni tored and measured postmortem and this has been the rationale of the 27


chemical based tests for drowning (discussed in chapter 3). In the case of drowning in a hypertonic medium (e.g., sea water) the reduction in the liq uid component of the blood results in increased osmolality and viscosity that may impair pulmonic perfusion and contribute to the VIQ mismatch that occurs due to alveolar distension with fluid. The magnitude of the change in the electrolyte concentrations that occur in sea water drowning (hypematremia and hyperchloremia) and freshwater drowning (hypona tremia, and hypochloremia) are usually not lethal.

* 4. PATHO LOGY OF FRESHWATER DROWNING Introd uction The pathology of freshwater drowning is complex and still poorly under stood. The main difficulty is that, in many cases, the pathological features of drowning are non-specific or grossly unimpressive. However, the descriptive pathology of drow ning has been possible because some cases of drowning show numerous distinctive and florid lesions. Why some cases of drowning have extensive gross changes (e.g., massive pulmonary oedema, frothy air passages, mastoid air cell hemorrhages) and others cases show minimal oedema of the lungs and no other features of drown ing is unknown. It is true that, arguably, all the morphological features of drowning are non-specific and can be potentially explained by other processes (i.e. oedema of the lungs is not specific for drowning). In the daily practice of forensic pathology, this is usually not problematic since circumstantial evidence provides additional information that may con tribute to the weight of the evidence for determining that death occured by drowning. However, since the lesions of drowning are problematic, ancil lary tests such as the diatom test have an important role in the medicole gal assessment of putative victims of drowning. The problem associated with the determination of death by drown ing is eloquently illustrated by famous case of The Man Who Never Was in which the tenuous nature of the morphological features of drowning are paramount. In 1942, intelligence officers Lieutenant-Commander Ewen Montagu and Flight-Lieutenant Charles Cholmondeley developed Operation Mincemeat to facilitate the Allied invasion of Scilly (9). Their plan was to plant a dead body ("Major Martin") into the Mediterranean

28

Pathology of Drowning ~~

.

:: . In the case of

~~_ ::jon

in the liq d viscosity _ -;: ·IQ mismatch I;ater drowning . :ning (hypona-

ING

_

. poorly under ~" _ .)gic al featu res

...:..:, -iYe pulmonary -:- ~e ) and others :e-.::ures of drown . . __ical features of ~ :-. 'ned by other ~:- .::-owning). In the _. "'-ublematic since ::-. (bat may con ~ I:..eath occured by .. :-:- . lematic, ancil . .. the medicole - _:-death by drown ,' }10 Ne ver Was in ~ _ f drowning are . -" .:' ~nm ander Ewen

~ - == :ey developed - .: : Scilly (9). Their :..-::: Mediterranean

Sea complete with documents indicating Allied plans for an invasion of Sardinia, contradictory to the real plan to infiltrate Scilly. The body was to land on the Spanish shore and the bogus document would bo transmitted to the Germans. The main diffculty according to Montagu was: "What would a postmortem reveal?". Montagu consulted Sir Bernard Spilsbury who indicated that there were no major pathological barriers to the plan, presumbly due to the difficulty in excluding drowning as a cause of death in a body recovered from the open sea. Furthermore, when Montagu obtained a suitable corpse to become "Major Martin" he learned that the individual had probably died of pneumonia. Sir Bernard indicated that .. .the pneumonia was a help, for there would tend to be some liquid in the lungs, as might well be the case if the man had died while floating in the rough sea. If a postmortem examination was made by someone who had formed the preconceived idea that the death was probably due to drown ing there was little likelihood that the difference between this liquid, in the lungs that had started to decompose, and sea water would be noticed.

Indeed, a postmortem examination in Spain concluded that death was due to drowning and the bogus documents were accepted as authentic. Postmortem findings in freshwater drowning include the lesions of drowning as well as the alterations that occur due to immersion and decomposition in water. Special importance can be placed on perimortem injuries that may indicate the events immediately preceding death.

Perimortem Injury and Events Several important perimortem injuries and changes can be observed in freshwater drowning . Some of these observations such as cutis anserina, ("gooseflesh" ) are no longer believed to have diagnositic utility. Among the most important posmortem indicators of live entry into water is cadav eric spasm in which the decedent may grasp at vegetation or clothing dur ing drowning and the articles may be tightly bound in the hand due to "instantaneous" rigor mortis. Abrasions of the face and nose may be found if there was a terminal collapse into the water. Other injuries may suggest homicidal drowning (e.g., evidence of neck injury or blunt force head injury).

29


An important type of injury that infrequenly occurs in open water drowning is avulsion and hemorrhage into the muscles of the shoulder gir dle (Fig. 2.14). This is due to a violent struggie that may ensue in the drowning process were the decedent thrashes and forcibly extends the arms against clothing or stable objects in the water. The violent contrac tion results in local tearing of the muscle from the periosteum of the scapu la. The injuries must not confused with blunt impact injuries of the back that may occur in ligature strangulation using a posterior assault.

Water-related Alterations The main water-related change that occurs after several min utes of immer sion (approximately 20-30 minutes) is pallor and wrinkling of the skin of the soles of the feet and palms, so-called "washerwoman skin" (Fig. 2. 15). This change can also be found in the skin in other parts of the body but in the early stages is less conspicious. Water immersion may alter the appear ance of recent wounds of the skin including lacerations and incised wounds, resulting in pallor of the wound margin. In this case, local dis section of the wound may be necessary to determine if local subcutaneous hemorrhage is present indicating an antemortem inj ury. Similarly, post mortem wounding of a body floating in rocky water may occur and dis section will fail to reveal local hemorrhage. The distribution of lividity will be effected by the position in which the body floats . In some circumstances, lividity may be concentrated in the head and neck region, particularly if the body floats in the face down posi tion for several days. This position, along with aquatic decomposition, may result in boggy red discolouration of the subcutaneous and subgaleal tissues that must be differentiated from recent hemorrhage.

Air Passages The main lesion of freshwater drowning is found in the air passages. The classical finding is the presence of abundant stable white foam that emerges from the nose in a mushroom-like fashion (Fig. 2.16). Similar foam can be found in the mouth, and tracheobronchial tree. The foam is moderately resistant to decomposition, which may stain the foam a red brown colour. The stability of the foam is due to the presence of alveolar 30

Pathology of Dro wning

_ - _. in open water _ .e houlder gir ~ . ensue in the . ~-: ~ \' extends the

2.14. Stable foam emerging from the nose in freshwater drowning. Per imortem blunt force injuries to the bridge of the nose, lower lip, and chin are due to terminal collapse. 2.15. "Washerwomen feet" due to water immersion. The skin of the soles of the feet and palms most frequently show this effect of water.

~

he body but in _ alrer the appear ~ ns and incised . . - case, local dis

: --0.

::~

2.14

2.16. Avulsive injury and fresh hemor rhage in shoulder girdle muscles in a case of suicidal freshwater drowning. Injuries of the shoulder girdle muscles are due to violent thrashing while drowning. (Case of Dr. D.A. Chiasson).

ition in which entrated in the ecomposition, - and subgaleal

-e . passages. The e white foam that F~ . 2.16). Similar ::ree. The foam is :-. me foam a red ~=::- ence of alveolar 31


surfactant, which along with the drowning medium and transudative oede ma fluid, comprise the foam. The air passages may also contain water if large amounts of water has been inhaled in the drowning process. If the water contains particulate matter, this may be found in the fluid including fragments of vegetation, and gravel. However, water and particulate matter may enter the trachea of a dead body immersed in water particularly if decomposition is advancing in an aquatic enviroment. Therefore, the presence of water and and foreign matter in the decomposed body from water may not indicate drowning. It is often helpful to open the sphenoid sinuses in cases of putative drowning since the presence of fluid in this site may occur in the absence of fluid elsewhere in the respiratory tract. Watery-fluid from this site can also be sampled for diatom analysis if samples of the putative drowning medium are unavailable for comparison with diatoms extracted from tis sues. The stomach may contain large amounts of water since swallowing water often occurs in drowning prior to inhalation of water. However, the utility of watery-fluid in the stomach as a sole sign of drowning is prob lematic since the water may have been recently ingested some time prior to immersion. The diatoms of the fluid in the stomach may be useful in discriminating, if tap-water or freshwater was ingested, since the former usually lacks diatoms (10).

Lungs In the classical circumstance, the lungs in drowning are hyperinflated and may show indentation from ribs, and the medial edges of the lungs may meet a the centre of the mediastinium ("kissing lungs"). The main gross lesion of the lungs in freshwater drowning is oedema. The pulmonary oedema of drowning has been studied mostly by deterntining the weight of the lungs in case of drowning. In cases of freshwater drowning 90% of cases have lung weights between 500 and 1, 000 grams which is greater than lungs from non-drowning death that have hlllgS weights typically between 400 and 500 grams (11). UnfOltunately, there is overlap between the lung weight of the approximately 15% of drowning cases when com pared with non-drowning cases. In addition, the nonspecificity of pul monary oedema make the weight of the lung, as a sole indicator of drown ing, of lintited value. However, in cases of drowning with foam in the air

32


" - of water : - ~, - particulate " f vegetation, _--"'!' :he trachea of .: ;:: i5 advancing _- ~ j and foreign __-c: Jrow ning. ;: of putative ~.~

:hi s site can _..::: e drowning '-..:. :,ced from tis -. :e swallowing ii=

the former

-_ :--:. rerinflated and .__ ,~ [he lungs may ~_ . The main gross The pulmonary : ::-:- ' -. ing the weight -;: ':':0 \'ning 90% of ,- ,,-ruch is greater = ,,:;:' ghts typically '_ - :werlap between - ~ ;: ' -es when com -- __ ci ficity of pul e rr: '::cator of drown ,::--. 'oam in the air

passage the magnitude of the lung weights may be an important consider ation in determining if drowning occured. Clearly, the positive predictive value of pulmonary oedema increases with the weight of the lungs in the appropriate investigative setting. The microscopic fingings is freshwater drowning include emphysema aquaosum and oedema aquaosum (Fig. 2.17-2.20) (10). Emphysema aquao sum refers to the local or regional expansion of alveolar spaces and oedema aquaosum refers to proteinaceous-fluid in the alveoli. Both these findings are non-specific but may be extensive in some cases of drowning, usually the cases with impressive gross evidence of drowning and diatoms in the femoral bone marrow. It may be possible to find diatoms in routine tissue sections pre pared in cases of freshwater drowning (Fig. 2.21-2.24). Despite the rapid death, alveolar macrophages can occasionally be found to contain phagocy tosed diatoms (Fig. 2.20). There is some evidence that alveolar macrophages may be "washed out" of the lung in drowning, although this does not appear to be an important microscopic feature of the lung in drowning (12). A non-specific finding in many cases of drowning in stagnant pools of water, and "hot-tub" baths is advanced postmortem bacterial overgrowth in the terminal bronchioles and alveolar ducts. Bacteria-laden water innocu lates the distal airways and the bacterial proliferate in the early postmortem interval. Microscopic examination will reveal preferential bacterial over growth in the distal airways and little or no growth of bacteria elsewhere in the lung or in other organs. If an individual survives an episode of near-drowning only to suc cumb later in hospital, the lungs may show diffuse alveolar damage andlor bacterial pneumonia. The diffuse alveolar injury is typified by hyaline mem brane formation, and type II pneumocyte proliferation and may show exten sive organization and interstital fibrosis if the survival interval is prolonged. In this circumstance, there is usually accompanying anoxic encephalopathy. The bacterial pneumonia is likely due to bacteria introduced into the lung by drowning. The pattern is usually diffuse rather than preferentially in the lower lobes.

Pleural effusion The presence of fluid in the chest cavities is variable in freshwater drown ing, and is likely due to diffusion of inhaled fluid from the lungs. In the 33


2.17-2.20. Microscopic Features of Freshwater Drowning. 2.17. Emphysema aquao sum (250 X). 2.18. Oedema aquaosum (250 X). 2.19. Localized bacterial over growth in lung (400 X). 2.20 Alveolar macrophage containing a centric diatom-like particle (1,000 X) (Haematoxlyin-eosin).

34


·r .

2.24

:="'l1pbysema aquao .: :- ~:erial over growth ~ ~ ::'~:llOm-like particle

'{y :',;

2.21-2.24. Diatoms in Lung. 2.21-2.23. Diatom frustules in alveolar air spaces (Haematoxlyin-eosin, 1,000 X). 2.24. Diatom frustule at alveolar wall (Toluidine blue, 1,000 X).

35


fresh state, the fluid is serous or slightly serosanginous. H owever, as decomposition precedes, decompositional fluid may appear in the chest cavities that may be confused with the pleural effusion of drowning. Hemorrhage in the Petrous Temporal Bone

Often the air cells in the petrous portion of the temporal bone will show extensive congestion and hemorrhage in cases offreshwater drowning ( 13) (Fig. 2.25). When the lesion is present it is conspicious although there are no studies on the sensitivity and specificity of the lesion for drowning. Florid congestion and hemorrhage into the temporal bone can also be observed in ligature strangulation presumably due to jugular venous obstruction. However, a similar appearance of the temporal bone may also be observed in non-violent deaths particuarly if the position of the head causes lividity at the skull base. The diagnostic significance of this find ing, although associated with drowning is uncertain at present.

Visceral Organs The main parenchymal organs that have been studed in drowning are the heart and spleen. No specific lesions of the myocardium or the spleen have been found in drowning. However, there may be contraction banding in cardiac myocytes in cases of drowning with significant atherosclerotic coronary artery disease (14). The spleen in freshwater drowning may be slightly reduced in size, although the significance of this observation is not known (15).

* 5. PINK TEETH The History of Pink Teeth

The subject of postmortem pink or red colouration of the teeth has been long investigated in the scientific literature and was first described by Bell in 1829 (16): I have frequently examined the teeth of persons whose death has been occasioned by hanging or drowning, and invariably found the whole of the osseus part coloured with a dull deep red, which could not possibly have been the case if these structures were devoid of a vascular system.

36


_

. ;.!owever, as in the chest

, 3r

- ::>!1e will show .;'c" Jrow ning (13) _ -'")r drowning.

also be .. .:ular venous :' ne may also _""",",""'n_,n .. of the head .-e of this fi nd _ -tC ~an

_~0\\'n ing

are the c :: :he spleen have _:on banding in

2.25 Mastoid air cell hemorrhage in freshwater drowning.

_ -ervation is not

~ =-.e

teeth has been : ':e cribed by Bell

- . ossibly have

37


Since the observations of Bell, several reseachers have studied the mech anism and frequency of pink teeth in bodies that undergo medicolegal postmortem examination (17-23). The most famous series of cases were the victims in the Christie case of 1953 (19,23,24). During the investiga tion of the case, after the accused confessed to the murders , the bodies of two of his victims were exhumed. At the original postmortem examination (about 3 years prior to exhumation), the cause of death for both victim was ligature strangulation without mention of pink teeth. At exuhrnation, pink teeth were found in one vicitm. No carboxyhemoglobin was detected and spectroscopic and and the benzidine reaction suggested that the pigment was derived from hemoglobin. The Christie case initiated debate over the sensitivity and specificity of pink teeth for asphyxial modes of death. The chemical composition of the pink pigment is now well characterized and likely originates from hemogloblin or proteolytic fragments of hemoglo bin. This has been confirmed by direct biochemical characterization of the pigment using spectrophometry, histochemistry, and thin layer paper chro matography (25-28) . Although postmortem pink teeth have been described in hanging, barbituate toxicity, carbon monoxide toxicity, and strangulation, the most consistent association occurs with drowning (24). In addition, pink teeth are not associated with freshly drowned bodies but usually occur after 1-2 weeks of aquatic decomposition. A critical examination of the forensic lit erature on postmortem pink death indicates that there are two possible and non-mutually exclusive mechanisms to form pink teeth. The prerequisites for the genesis of pink teeth include: 1. Congestion and extravestation of blood in the tooth pulp. 2. Decomposition - particularly in a moist or aquatic environment. The first prerequisite occurs in two major circumstances, either through a congestive mode of death such as occurs in strangulation (mostly ligature strangulation as in the Chrisite case) or when lividity accumulates in the head due to positioning of the body (as in aquatic decomposition) . In the circumstance of strangulation, the blood vessels in the pulp presumably rupture and spill blood pigments that subsequently stain the tooth after decomposition. In the case of lividity of the tooth, decomposition and 38

Pathology of Drowning ~c:ed

the mech

. --:e:::: examination =,m victim was _bnation, pink - detected and

- - =...Jr'on, the most _22 :.on pink teeth occur after 1-2 - _.:: ~: e forensic lit ': _,' 0 possible and ..e prerequisites

hemolysis may give the same net effect without initial antemortem con gestion. On this basis, the presence of pink teeth is less an indicator of the cause of death but rather, in some cases, the mechanism of death and the effects of decomposition on the congested tooth pulp.

The Significance of Pink Teeth Pink teeth are not pathognomonic for a specific cause of the death. Although initial studies showed a consistent association with unnatural death and drowning, it is now appearant that other causes of death (e.g., gun shot wounds, explosion, natural causes) can also be associated with the pink teeth if decomposition occurs in the appropriate environment. However, the initiating event of pink teeth formation in an individual case may be related to a congestive mode of death such as strangulation. In such as circumstance, postmortem pink teeth relate to the mechanism of death despite the fact that no definitive conclusion can be made about the presence of pink colouration of the teeth. Pink teeth in drowning likely relates more to aquatic decomposi tion with congestion of the tooth pulp associated with drowning or float ing in the head down position (i.e. lividity). Therefore, pink teeth are not definitive for drowning but, rather, are part of the spectrum of changes that occur in aquatic decomposition.

* 6. AQUATI C DECOMPOSITION Aqu atic Ta phonomic Factors

·!Unment. __ . either through a . _. mostly ligature .:.:' 1ffiulates in the '::~. sition). In the :: ul p presumably 2~. he tooth after ':c' mposition and

The progressive dissolution of the body in water is due to the action of sev eral independent degradative forces , termed taphonomic factors (29-33) . The factors include both intrinsic properties of the body itself and envi ronmental factors such as water temperature, the presence of aquatic scav engers , the action of currents, tides, and rocks in the water, and depth of the water. Aquatic decomposition is a dynamic process that does not fol low a specific timetable and can be slowed or arrested by changes in water temperature that occur with seasonal variation or with depth of submer sion. Since there is an inverse correlation of depth with water temperature, bodies exposed to cold deep water for several years may show only mod erate decomposition. 39


Putrefaction in water may lead to dismemberment of the body due to the action of currents, boat propellors, and canal locks. Unlike terrestri al decomposition, animal scavenging is not a major taphonomic factor for aquatic putrefaction since most marine saprophytes do not dismember. However, the action of crabs, shrimps, and other crustaceans may produce localized marks of the fleshy parts of the face that must be distinguished from antemortem injury. It is not uncommon that decomposed body in water is fragmented or artefactually disrupted upon recovery from the water. Such postmortem injuries must be distinguished from antemortem wounds. One pruticularly common artefact that occurs on bodies recovered from water is the impres sion of metal mesh of the stretchers that rescuers may use to transport the body to the mortuary. This mesh leaves a distinctive impression on the skin especailly on the face if the body is prone. These postmortem pressure marks must not be confused with antemortem injuries. Decomposition Sequence in Freshwater

Aquatic decomposition, like decomposition on land, progresses through a well-defines series of stages (30-32) (Fig. 2.26-2.29). However, the rate of progression through the various stages is too variable to be used as a defin itive guide to determine the time interval between deathlimmerison and discovery of the body. Several variables control the rate of progression through the decompositional sequence, including, but not limited to, water temperature, body composition, whether the body is floating or complete ly submerged, and the influence of natural forces such as tides. In general the sequence progresses from a fresh body to fragmented skeletonized body over a period of months but may take several years. An "average" decomposition sequence starting with a fresh body commences with rigor, and livor mortis, and early discolouration of skin (0-2 days). Early decompsition (2-7 days), results in extensive discoloura tion, bloating, and early putrefaction of organs. After 1 week to 2 month there is advanced decomposition with the onset of adipocere formation, fragmentation, and extensive putrefaction. From months to years the body may become skeletonized with exposure of bones, and encasement by adipocere.

40


: L:- the body due . '__ nlike terrestri

dismember. _"'.:..:)- may produce - .~ distinguished

_ . ..ut

_::.c~:

the impres .;: :) Iransport the _:: _-ion on the skin

.:_~:' unmerison and

_ . _:~ of progression

- _: imited to, water

- : _:..ing or complete · - _. -ides. In general

· ~~. :ed skeletonized

~~

. :th a fresh body · _. _.ouration of skin :en ive discoloura - _ ·.\·eek to 2 month ere formation , - .0 years the body - ~ encasement by

2.26-2.29. Stages of decomposition in freshwater. 2.26. Hair loss, skin slippage, bloating, and green-white discolouration of skin. 2.27. Early water-related changes of the skin with slippage and pre-adipocere fOImation. 2.28. Extensive water denudation of muscle and soft tissue with exposure of femur. 2.29. Adipocere fonnation of the entire body (inset, close-up of adipocere). 41


Adipocere Adipocere ("grave-wax") is a white-waxy substance that is the product of the hydolysis and hydrogenation of fatty acid (e.g., oleic acid) in the adi pose tissue of dead bodies (34) (Fig. 2.29, inset). Adipocere fonus during decomposition in an aquatic or moist humid environment and is remark ably stable once formed. In the early stages, the hydrolysed adipose tissue of the subcutis may herniate through adnexal pores in the skin and hard ens as the chemical process of adipocere formation continues. The result is that the skin is encased in a waxy substance that may harden as a solid protective layer for the long bones and organs. Adipocere may preserve a corpse for years in the water. The presence of a protective layer of adipocere on the leg makes the femoral bone marrow an excellent choice for the starting material to extract diatoms in decomposed bodies found in water. The mechanism and temporal seqence of adipocere formation has been the topic of extensive study (35-39). Adipocere formation usually takes about 2 months, but is highly variable and cannot be used as a reli able indicator of the time of submersion. Water temperature seems to be a key factor in adipocere formation, and immersion in a cool medium may prolong adipocere formation for one year or longer (35). The biochemical pathway to adipocere from lipid is complex but appears to involve the action of bacterial catalysis by both anaerobic or aerobic microbes (36) (e.g., Micrococcus luteus) .

* 7. REFERENCES 1. Camps FE Hunt, A.c. Pressure on the Neck. Journal of Forensic Medicine 1959;6:116-135. 2. Gonzales TA. Manual strangulation . Archives of Pathology 1933;15 :55-66. 3. Luke JL. Strangulation as a method of homicide. Archives of Pathology 1967 ;83 :64-70. 4. Jaffe FA. Petechial hemorrhages: A review of pathogenesis. American Journal of Foresnic Medicine and Pathology 1994;15(3):203-207. 5. Takeichi S Wakasugi, c., Shitkata, 1. Fluidity of cadaveric blood after 42


~':e

,orms during ~e::.: and is remark . .:. c adipose tissue - ~ skin and hard

:001 medium may _- :-he biochemical ..:.:~ to involve the - _: - microbes (36)

= _:TI

e.:.

I of Forensic of Pathology

,... ~: ': e . Archives of

.e ~~e' : . American

- _: : :_03-207. _~. eric blood after

sudden death: Part II. Am J Forensic Med Pathol 1985;6:25-29. 6. Mizutani Y Yamada, T., Sugie, 1. Studies on the fluidity of cadaveric blood in sudden death: Fluid blood in the cadaver from the view point of clotting function. Jpn J Legal Med 1978;32:277-284. 7. Modell l H. The pathophysiology and tretment of drowning and near drowning. Springfield, IL: Charles C. Thomas Publishers, 1971 8. Gettler AO. A method for the determination of death by drowning. 1. Amer. Med. Assoc. 1921 ;77: 1650-1652. 9. Montagu E. The Man Who Never Was. (2nd edition (first edition, 1953) ed.) Great Britian: Oxford University Press, 1996 10. Polson CJ Gee, DJ., Knight, B. Drowning. In: The Essentials of Forensic Medicine. Oxford: Pergamon Press, 1985: 11. Copeland AR Assessment of lungs weights in drowning cases. American Journal of Forensic Medicine and Pathology 1985;6:301 304. 12. Betz P Nerlich, A., Penning, R., Eisenmenger, W. Alveolar macrophages and the diagnosis of drowning. Forensic Science International 1993;62:217-224. 13. Mueller WF. Pathology of temporal bone hemonhage in drowning. Jounral of Forensic Sciences 1969;14(3):327-336. 14. Lunt DWR Rose, A.G. Pathology of the human heart in drowning . Archives of Pathology and Laboratory Medicine 1987; 111 :939-942. 15. Haffner HT Graw, M., Erdeikamp, J. Spleen findings in drowning. Forensic Science International 1994;66:95-104. 16. Bell T. Anatomy, physiology and disease of teeth.London: Stewart and Company, 1829:9-17. ; vol 1829). 17. Beeley JA. Pink teeth appearing as a post-mortem phenomenon. Journal of the Forensic Science Society 1973;13:297-305. 18. Kirkham WR Andrews, E.E., Snow,C.c., Grape, P.M., Synder, L.. Postmortem pink teeth. J Forensic Sci 1977;22: 119-13l. 19. Whittaker DK Thomas, v.c., Thomas, R1.M. Post-mortem pigmenta tion of teeth. Br Dent J 1976;3:100-102. 20. Brondum N Simonsen, J. Postmortem red coloration of teeth. Forensic Odontology 1987;8(2):127-130. 2l. Miles AEW Fearnhead, RW. Post-mortem color changes in teeth. Journal of Dental Research 1954;33:735. 43


22. Brondum N Simonsen, l Postmortem red coloration of teeth. A retro spective investigation of 26 c ases . A m J Forensic M ed Pathol 1987;8: 127- 130. 23. Borrman H Du C hesne, A., Brinkmann, B. M edico-legal aspects of postmortem pi nk teeth. Int 1 Leg M ed 1994 ;106:225-231. 24. Brondum N Simonsen , l Postmortem red colouration of teeth . American 10urnal of Forensic M edicine an d Pathology 1987;8(2): 127 130. 25. Van Wyk CWo Postmorte m pink teeth : in vitro production. J Oral Pathol Med 1988; 17 :56,8-572. 26. Sainio P Syrjanen, S., Kellala, l, Parvianen, A. Postmortem pink teeth phenomenon : an experimental study and survey of the literature. Proc Finn Dent Soc 1990;86:29-35. 27. lk:eda N H arada, A, Takahashi, H ., Suzuki, T. Experimental formation of pink teeth and their analysis. 1pn 1 Legal M ed 1988;42: 179- 183. 28. Van Wyk CWo Postmortem pink teeth: H istochemical identification of the causative pigment. Am J Forensic Med Pathol 1989;10:1 34-139. 29. N awrocki SP Pless, lE., Hawley, D.A. , Wagner, S.A Fluid transport of h uman crania. In: H aglund WD Sorg, M.H ., ed. Forensic Taphonomy: T he postmortem fate of human remains. New York: C RC Press, 1997: 529-552. 30. B rooks S Brooks, R.H . The taphonomic effects of flood waters on bone. In: Haglun WD Sorg, M .H. , ed. Forensic Taphonomy:The post mortem fate of human remains. New York: e Re Press, 1997: 553-558 . 31. B oyle S Galloway, A , M ason, R. T. Human aquatic taphonomy in the M onterey Bay area. In: Haglund W D Sorg, M .H ., ed. Forensic Taphonomy: The postmortem fate of human remains. New York: e Re Press, 1997: 605-613. 32. Sorg MH Dearborn, l H ., Monahan, E.I., Ryan, H.P., Sweeney,K.G., David, E. Forensic taphonomy in marine contexts. In: Haglund W D Sorg, M .H., ed. Forensic Taphonomy:The postmortem fate of human remains. New York: CRC Press, 1997: 567-604. 33. O'Brien TG. Movement of bodies into Lake Ontario. In : Haglung WD Sorg, M .H., ed. Forensic Taphonomy:The postmortem fate of human remains. New York: eRe Press, 1997: 559-565. 34. Mant AK Furbank, R. Adipocere - A review. 10urnal of Forensic 44


:- :eeth. A retro :: \1ed Pathot

.'- ~ m pink teeth . ~: [erature. Proc - ..ental formation .. :.+2:179-183. . _ _dentification of :: 9: 10:134- 139. .:: .A. Fluid transport R .. d . Forensic - - _-ew York: eRe

Medicine 1957;4(1):18-35. 35. Mellen PFM Lowry, M.A., Micozzi, M.S. Experimental observations on adipocere formation. J Forensic Sci 1993;38:91-93. 36. Takatori T Gotouda, H. , Terazawa,K., Mizukami,K., Nagao, M. The mechanism of experimental adipocere formation: substrate specificity on microbial production of hydroxy and oxo fatty acids. Forensic Sciences International 1987;35:277-281. 37. Gotouda A Takatori, T. , Terazawa, K., Nagao, M. Tarao, H. Experimental adipocere formation: Hydration and dehydration in microbial synthesis of hydroxy- and oxo- fatty acids. Forensic Science International 1988;37:249-255 . 38. Takatori T Yamaoka, A. The mechanism of adipocere formation: II Separation and identification of oxo fatty acids in adipocere. Forensic Science 1977;10:117-125. 39. Takatori T Yamaoka, A. The mechanism of adipocere formation. I Identification and chemical properties of hydroy fatty acid in adipocere. Forensic Sciences 1977;9:63-73 .

~:-

flood waters on - _:- ..onomy:The post 1997: 553-558 . . - :aphonomy in the _.H.. ed. Forensic :: '\"ew York: eRe

-

=--.

...: ?.. Sweeney,K.G., . In: Haglund WD _~e!TI

fate of human

..:-:; b : Haglung WD ~ -:-:=:::-. fate of human ~ _ ~al

of Forensic 45

3. The medicolegal value of the diatom test for drowning

* 1. ANALYTICAL APPROACHES TO DROWNING Laboratory approaches to the postmortem diagnosis of drowning can be divided into two basic procedures: the chemical detection of a change in blood volume status due to drowning or the detection of aquatic micro organisms in the greater circulation or organs. The chemical tests depend on the flu id component of drowning medium, whereas the other method depends on particulate components. The common theme in both approach es is to examine a parameter in the body that changes after drowning medi um enters the lung and blood. The chemical tests for drowning are largely historical and not widely practiced. The principle reason for this is the large variability in postmortem electrolyte concentration that occurs as a function of the postmortem interval. While the micro-organism based tests are more widely used, the aquatic micro-organsim of choice is the diatom, rather than other aquatic organisms such as protozoa, dinoflagellates, or invertebrates. The preference for diatoms relates to technical considera tions and the postmortem stability of the diatom in human tissue. Chemical Tests for Drowning The basis of most chemical tests for drowning is that fluid in the drown ing medium passes into the left sided heart blood via the alveolar-capillary

47


barrier resulting in hemodilution if the fluid is hypotonic (freshwater) or hemoconcentration if the fluid is hypertonic (salt-water). Most investiga tors have studied hemodilution due to freshwater drowning. In principle, drowning-associated hemodilution can be measured by the concentration of a solute in the left heart blood as compared with the right heart blood, thereby determining the magnitude of hemodilution using the equation, (SR - SL) / SR' where SR is the solute concentration in the right heart blood and SL is the solute concentration in the left heart blood. Most investiga tors have directly measured electrolyte concentration and calculated the hemodilution factor or used freezing-point determination of the osmolali ty of the plasma (1-4) . Popular variations on the hemodilution test are to assay the electrolyte concentration of other fluid compartments that change with blood volume and electrolyte alterations including the cere brospinal fluid and the vitreous humor. The first ion used to assay hemod ilution was chloride as described by Gettler in 1921 (5). Unlike potassium and other plasma ions, the chloride concentration of postmortem blood is relatively stable and can, in some cases, be used as a index of hemodilu tion in freshwater drowning. In addition, when drowning occurs in a hypertonic medium such as salt-water, hemoconcentration of the left heart blood may increase the chloride concentration. Similarly, hypertonicity of the drowning medium may lead to pleural effusion that has a chloride con centration greater than that of normal plasma (6). Unfortunately, the post mortem concentration of all plasma ions changes with postmortrem inter val such that the values obtained in drowning and non-drowning cases overlap too extensively to be useful in those cases of drowning that have values in the borderzone. An important and promising variant of the hemodilution test is the quantification of blood strontium levels in cases of drowning (7-9). Strontium is a trace metal that is found in relative abundance in the crust of the earth. On this basis, strontium is widespread in sea-water and, to a lesser extent, other naturally-occurring bodies of water and even domestic water. Since strontium has a low concentration in the plasma, the addition of minute amounts of strontium into the blood during drowning may lead to relatively large increases in the strontium concentration in the blood. The level of strontium in drowning cases is dependent on the strontium content of the water; salt-water drownings have higher strontium levels 48

Medicolegal Value of the Diatom Test

~

, ~ o- t

investiga - "' ~ . In principle,

Micro-organism Tests for Drowning

_::on test are to _ :: . " artments that - ':,JJing the cere _ ~ _:0 say hemod : ~':-. :ik:e potassium :- .:: .:: ·~ ortem blood is _ - ':eX of hemodilu ~,-=--1] g occurs in a .:: of the left heart __ . . !:lypertonicity of :::. a chloride con ~ :, _,Eately, the post [[u ortrem inter ~ ~ -drowning cases - ~(" w ning that have ~

than freshwater drownings. Therefore, strontium analysis may be useful for the diagnosis of drowning particularly in the salt-water environment. One of the limitiations of the test is that the detectable strontium is corre lated with the length of time of aquatic decomposition, making the test of questionable value in decomposed bodies recovered from water.

:- . .j it tion test is the

_~ . owning (7-9). __-:.:a.nce in the crust - _'"_-\ ater and, to a ~ ... -=d even domestic :.. . _ -ma, the addition =- .: ~ 'Ding may lead _', n in the blood. _ - r ::':1 the strontium _ ~: 5 ~ rontium levels

The introduction of drowning medium into the pulmonary capillary bed allows both the fluid and particulate components of the medium to enter the circulatory system. This particulate matter ranges from micro-organ sims to amorp hous inorganic debris (e.g. microscopic sand grains). The presence of micro-organisms in the lung parenchyma, tracheobronchial tree, and circulation and its organs has been extensively studied, mostly in the context of diatoms. However, diatoms are not the only aquatic organ isms detected in the tissues of the the drowned. Other important organisms include chlorophyta, dinoflagellates, invertebrates such as Daphnia, and the protozoans including the ciliate Tetrahymena (1 0-18). In the case of Tetrahymena, the ciliate can be propagated in culture indicating that the organism entered the body alive during the drowning process (19). In one study, the presence of diatoms in the left atrial blood was also correlated with the presence of alveolar macrophages with anthracotic pigment indi cating the point of origin of the diatoms (18). In theory, the presence of any aquatic micro-organism derived from the drowning medium in the tissues of a drowning victim is sufficient to prove drowning. However, diatoms are the preferred organism for detection in the laboratory. This relates to several important features of the diatom including the stablity of the siliconiferous exoskeleton (frustule) and the abundance of diatoms in bodies of water. T he stability of the diatom allows relatively easy extraction from postmortem tissues. Other organisms such as the ciliates, and dinoflagellates have delicate cell membranes that cannot resist the harsh extraction procedures usually employed.

* 2. THE SO-CALLED "WA R-ON-DIATOMS" Spitz has referred to the debate on the validity of the diatom test for drowning as the "war-on-diatoms" (20). Before discussion of the scientif 49

Forensic DiatomoLogy and Drowning

ic aspects of research on diatoms and drowning, it is useful to understand the nature of the debate and how this debate emerged. The "war-on diatoms" appears to be that medicolegal facilities in Europe more fre quently utilize the test than in North America. This may be due, in part, to the origination of the test in Europe and the relatively minor contribution of American researchers to the scientific aspects of diatoms and drowning. In addition, many medical examiner's facilities in the United States lack appropriate laboratory facilities to extract diatom frustules from tissue, whereas many European departments of forensic pathology are housed in institutes of legal medicine or Universities. Despite the lack of the widespread use of the diatom test in the United States, the current state-of-the art assessment on the medicolegal significance of the diatom test for drowning is best summarized by the American forensic pathologists DiMaio and D iMaio in their standard text book on forensic pathology : The material , such as bone marrow, is digested in concentrated acid. The deposit is examined with a standard microscope for the presence of the diatoms. The water in which the individual has allegedly drowned is sam pled to see what type of diatoms are present and a comparison is made between that in the water and that foun d in the body. While a positive com parison is helpful, a negative result does not rule out drown ing. Even a completely negative analysis for diatoms does not rule out drowni ng ... Di Maio DJ, Di Maio VJM. Forensic Pathology, Elsevier, New York, pg 363-364, 2nd edition, 1993. The view of DiMaio and DiMaio is not unique among authorities in foren sic pathology; many classical texts of forensic medicine state similar views on the di atom test. M any of these books are considered the classical textbooks of forensic medicine. Professor Keith Simpson, of the Home Office in the U nited Kingdom, supported the use the diatom test in cases of drowning and advocated the use of bone marrow or brain as the starting material for extraction. In "Taylors Principles and Practice of Medical Jurisprudence", he wrote: Only the live body with a circulation could transport diatoms from the lung to the brain or marrow. Acid digestion does, in fact, reveal a remark 50

Medicolegal Value of the Diatom Test :- ~: 0

understand . The "war-on - _rope more fre _ ~ ue, in part, to rn.:..::or contribution _-- - and drowning. '_'::::ired States lack __:es from tissue, - ;. =. - are housed in r'-'"

Eight years later, after further scientific research was published, he sum marized his views on the test as follows:

~

atom test in the the medicolegal ... ~arized by the :.:,.cir standard text

:.=nrrated acid . The -~ presence of the . _fow ned is sam • _ T"'. arison is made e positive com

O\-vning. Even a

:: __ _drowning ...

~ . New York, pg

= _.J :borities in foren '::.ne state similar ,... :..ered the classical

in the United _ of drowning and r:ing material for : _ -:1 Ju risprudence",

-::

able collection of most delicate and beautiful diatomaceous bodies in brain, marrow and other specimens from cases of drowning--as distinct from immersion when dead, and the finding, if not absolutely diagnostic is of the greatest value. The balance of probabilities is, in our experience strongly weighted in favour of immersion in life when diatoms are found in the brain and bone marrow. Simpson K. Taylors Principles and Practice of Medical Jurisprudence, 12th edition, J & A Churchill Ltd., pg 377, 1965.

~ ro ms fro m the . =-e\eal a remark-

... microscopic diatomaceous matter rapidly enters the circulation in a live victim of drowning. Microscopy of spun acid digests of brain and bone marrow tissues will often provide this laboratory proof of immersion alive. A dead body thrown into the river shows no such changes, though water may run into the dead throat or upper air passages ... Simpson K. Forensic Medicine, 6th edition Edward Arnold publishers, pg 92, 1972.

Professor Francis E. Camps was also generally supportive of the reliabili ty of the diatom test: Whilst the tests are not necessarily conclusive, they provide reliable sup

portive evidence. Tests are made on all enclosed organs, skeletal muscle

and femoral bone marrow.

Camps FE. Gradwohls Legal Medicine, 3rd edition, Bristol: John Wright

& Sons Ltd., pg 353, 1976.

In one of the most influencial texts in forensic medicine, Polson, Gee and Knight expressed the view that the diatom test had particular value as a confirmatory test for drowning: The demonstration of plankton and, more especially, diatoms in the sub merging fluid and in the body of the victim, is of particular value as a con firmatory test. The test material is treated by acid digestion as a prelimi nary step in diatom analysis. In the case of decomposed bodies, the demonstration of diatoms in enclosed organs and especially in the bone marrow, due care being taken to exclude contamination, is strong if not conclusive evidence of death by drowning . 51


ic aspects of research on diatoms and drowning, it is useful to understand the nature of the debate and how this debate emerged. The "war-on diatoms" appears to be that medicolegal facilities in Europe more fre quently utilize the test than in North America. This may be due, in part, to the origination of the test in Europe and the relatively minor contribution of American researchers to the scientific aspects of diatoms and drowning. In addition, many medical examiner's facilities in the United States lack appropriate laboratory facilities to extract diatom frustules from tissue, whereas many European departments of forensic pathology are housed in institutes of legal medicine or Universities. Despite the lack of the widespread use of the diatom test in the United States, the current state-of-the art assessment on the medicolegal signific ance of the diatom test for drow ning is best summarized by the American forensic pathologists D iMaio and D iM aio in their standard te xt book on forensic pathology: The material , such as bone marrow, is digested in concentrated acid. The deposit is examined with a standard microscope for the presence of the diatoms. The water in which the individual has allegedly drowned is sam pled to see what type of diatoms are present and a comparison is made between that in the water and that found in the body. While a positive com parison is helpful, a negative result does not rule out drowning. Even a completely negative analysis for diatoms does not rule out drowning ... Di Maio DJ, Di Maio VJM . Forensic Pathology, Elsevier, New York, pg 363-364, 2nd edition, 1993. T he view of DiM aio and D iM aio is not unique among authorities in foren sic pathology ; many classical texts of forensic medicine state similar views on the diatom test. Many of these books are considered the classical textbooks of forensic medicine. Professor Keith Simpson, of the Home Office in the United Ki ngdom, supported the use the diatom test in cases of drowning and advocated the use of bone marrow or brain as the starting material for extraction. In "Taylors Principles and Practice of M edical Jurisprudence", he wrote : Only the live body with a circulation could transport diatoms from the lung to the brain or marrow. Acid digestion does, in fact , reveal a remark 50


efu l to understand _e rg d. The "war-on ~~ in Europe more fre . may be due, in part, to .- eol\" m inor contribution '- ~ '::atoms and drowning. -: :b.c United States lack J

able collection of most delicate and beautiful diatomaceous bodies in brain, marrow and other specimens from cases of drowning--as distinct from immersion when dead, and the finding, if not absolutely diagnostic is of the greatest value. The balance of probabilities is, in our experience strongly weighted in favour of immersion in life when diatoms are found in the brain and bone marrow. Simpson K. Taylors Principles and Practice of Medical Jurisprudence. 12th edition, J & A Churchill Ltd., pg 377, 1965.

Eight years later, after further scientific research was published, he marized his views on the test as follows:

--

~'0r

the presence of the . gedl. drowned is sam ~ _ omparison is made '- -...... Wh ile a positive com ~_ ;: out drowning. E ven a -, : rule out drowning ... _ • E:se\'ier, New York, pg

=,ng authorities in foren . -:. ~ dicine state similar ...I:: 2 0n idered the classical -" Office in the United - , es of drowning and :~.e tarting material for _: _ edical Jurisprudence",

-;:)rt diatoms from the

_ . fac t, reveal a remark-

u~

...microscopic diatomaceous matter rapidly enters the circulation in a Ii\"t~

victim of drowning. Microscopy of spun acid digests of brain and bon

man'ow tissues will often provide this laboratory proof of immersion ali ve.

A dead body thrown into the river shows no such changes, though water

may run into the dead throat or upper air passages ...

Si mpson K. Forensic Medicine, 6th edition Edward Arnold publishers, pg

92, 1972.

Professor Francis E. Camps was also generally supportive of the reliabiE ty of the diatom test: Whilst the tests are not necessarily conclusive, they provide reliable up

portive evidence. Tests are made on all enclosed organs, skeletal muscle

and femoral bone marrow.

Camps FE. Gradwohls Legal Medicine , 3rd edition, Bri stol: John Wri ght

& Sons Ltd ., pg 353, 1976.

In one of the most influencial texts in forensic medicine, Polson, Gee an . Knight expressed the view that the diatom test had particular value a ., confirmatory test for drowning: The demonstration of plankton and , more especially, diatoms in the sub merging fluid and in the body of the victim, is of particular value as a con firmatory test. The test material is treated by acid digestion as a preli mi nary step in diatom analysis. In the case of decomposed bodies, the demon stration of diatoms in enclosed organs and especially in the bone marrow, due care being taken to exclude contamination, is strong if n conclusive evidence of death by drowning. 51

j


Polson CJ, Gee DJ, Knight B . The Essentials of Forensic Medicine, 4th ed ition, Pergamon press, pg 434, 1985.

We now discuss some of the historically important reseach on the diatom test for drowning with specific reference to early investigations, recent studies on the reliability of the test and developments in empirical meth ods fo r isolating frustules from tissue.

* 3. A BRIEF HISTORY OF TH E DIATOM TEST An impressive volume of scientific investigation has been published on the issue of diatoms and drowning. The literature is chiefly devoted to the his tory of the test, the best choice of tissue for diatom detection, and indirect and direct studies of the specificty of the test for drowning. In the last decade, investigators have focu s ed attention on procedural modific ations to the classical methods of the test. Much of the classical literature on diatoms and drowning has been reviewed by Peabody (21). It may have been Revenstorf who first noticed diatoms in the lungs of the drowned in 1904 (22). However, Revenstorf credits Hofman with priority for this discovery eight years prior to his own work. However, there seems little doubt that Revenstorf conceived what is now generally held to be the important concept behind the diatom test; that diatoms could enter the systemic circulation through the lungs during drowning. The modem era of forensic diatom analysis was initiated in the 1940's by the work of the Hungarian investigators, Incze (12, 13, 23 -25) and Tamaska (26, 27). Incze demonstrated that the lungs, blood, and blood-filtering organs of rabbits drowned in suspensions of diatoms con tained diatoms. The specificity of parenchymatous diatoms was shown by immersing dead rabbits in a similar suspension and demonstrating that the peripheral organs lacked diatoms whereas some diatoms could be found in the lungs, presumably by passive infiltration in the postmortem period. Mueller and Gorgs (28-30) carrier out similar in vivo investigations inde pendent of Incze. Tamaska extended these observations by detecting diatoms in the tissues of witnessed drownings. Furthermore, Tamaska failed to demonstrate diatoms in the tissues of several non-drowning deaths that were recovered from the Danube river. 52


. . 1edicine, 4th

_-_::en on the diatom c tigations, recent :-: empirical meth-

TEST published on the deyoted to the his ~::'~~:ion and indirect ~~ 'Ding. In the last ;:~ Jral modific ations :';;c

jrowning has been " ,::"who first noticed .:' .:eyer, Revenstorf . ~...... prior to his own :-onceived what is . e diatom test; that _=' .he lungs during _ ... as initiated in the - ~?e (1 2, 13, 23-25) - ~·:g s . blood, and . 2f diatoms cor. _ :":':_ was sbo n b. _ -.., . :raling that £b:

c::

.:-~~ ... .d

be foun

:r.

It was not until after World War Two that diatoms and drowning became a major research focus in forensic medicine. In the 1960's and early 1970's investigators in Belgium led by Timpennan developed a comprehen sive research prorgam on the the practical application of the diatom test to death investigation (31-37). In 1969, Timpennan published the classic paper on diatoms and drowning, "Medico-legal Problems in Death by Drowning: Its Diagnosis by the Diatom Method" describing a decade of research (37). During the same period other investigators in Japan and the United States published similar data in general agreement with the work of Timpennan. For the first time, using a large series of drowning cases, Timpennan provided evidence for the validity of the diatom test by demonstrating: 1. Diatoms could be reproducibly recovered from human tissues in

freshwater drowning.

2. The acid-extraction method gave consistent results when applied to

several different tissues including bone marrow.

3. Quantitative analysis of the lung diatom burden may be useful in dif ferentiating live and postmortem immersion in water. 4. The concordance of the types of diatom in various organs and the

drowning medium was independent evidence for the validity of the

diatom test.

Studies on the diatom test for drowning in the last three decades have extended and strengthened these conclusions. H owever) at the time of the work in Belgium, some investigators suggested that the rationale for the diatom test may have been based on an erroneous postulate: that diatoms are absent in the tissues of the non-drowned. Spitz wrote: ... in 1963 we questioned the validity of this method by the recovery of diatoms in the liver and in other organs of individuals who had died of causes other than drowning. Spitz WU, Fisher RS . Medicolegal Investigation of Death, 2nd edition, Charles C. Thomas Publishers, pg 570, 1993. This led to the study of the specificity of the diatom test for drowning as determined by the ability to extract diatoms from the tissues of the non drowned.

53


* 4 . AR E DIATOMS UBIQUITOUS IN TISSUE? The main evidence against the validity of the diatom test for drowning is that some studies have found fru stules in tissue-extracts of cases of non drowning deaths (37-45) (Table 3.1). This finding has been interpreted to mean that the non-drowned, indeed anyone, may have diatoms trapped in tissues and that these diatoms did not enter the body by drowning (46). However, an equally logical explanation is that some, if not all, of these problematic diatoms originated in the laboratory rather than the tissues since studies show that there is no universal agreement on the presence of diatoms in the non-drowned. The two issues that have medicolegal impor tance and need consideration are: 1. Is there a plausible mechanism for entry of diatoms into the non

drowned?

2. What is the significance of the presence of spurious diatoms on the

diatom test for drowning?

A priori, diatoms can enter only enter the body by two routes: the respira

tory tract and the gastrointestinal tract. The fact that diatoms have been found in the air and diatomaceous pneumoconiosis (47) is known to occur indicates that diatoms may enter and reside in the lung. There is no empir ical evidence that extensive hematogenous dissemination of diatoms inhaled in the course of tidal ventilation reaches the parenchymal organs or bone marrow. It is also uncertain by what mechanism diatom that are resident in the lung could breach the alveolar-capillary barrier and evade local lung defenses (e.g. cilia, mucus, alveolar macrophages). However, it must be conceded that a massive pulmonary burden of diatoms may lead to disruption of lung homeostasis that may lead to diatoms escaping into the capillary bed. Evidence in support of this is that asbestos and berylli um may be observed in the peripheral organs of some individuals with asbestosis and berylliosis. On this basis, the empirical evidence would suggest that the diatom test for drowning could be confounded by the presence of spurious diatoms in individuals with diatomaceous pneumo coniosis. The empirical evidence for the entry of diatoms through the gas trointestinal mucosa is that liver may contain diatoms and diatom-like par 54


.

~e - t

for drowning is .~ ': - of cases of non ..:.:; been interpreted to ." diatoms trapped in .' by drowning (46). ~. if not all, of these ~ .er than the tissues

_ '1': on the presence of

e medicolegal impor-

TABLE 3.1 Specificity of the Diatom Test Using Various Organs t

# of Cases§

+

Study

Lung

5 0 7 6 4

5 18 28 15 13 16 29

0.22 0.96 0.84 1.00 0.65 0.72 0.88

Otto, 1961

Porowski, 1966 Koseki, 1968 Neidhart & Greendyke, 1967 Schneider, 1969 Timperrnan, 1969 Calder, 1984

21 I 6 6

29 1 30 14 12

0.97 0.05 0.97 0.70 0.67

Mueller, 1963 Spitz & Schneider, 1964 Koseki, 1968 Schneider, 1969 Ti mperrnan, 1969

18 21 14

0.95 0 .88 0.88

Porowski, 1966 Neidhart & Greendyke, 1967 Calder, 1984

18 1 12

0.95 0.06 0.40

Porowski, 1966 Schellman & Sperl, 1979 Calder, 1984

23

into the non diatoms on the

'- routes: the respira i diatoms have been - - is known to occur - g. There is no empir ~~ati on of diatoms . ?arenchymal organs , m diatom that are ~ . barrier and evade :-,hages). However, it - .:-:' diatoms may lead :::....1.roms escaping into stas and berylli ~~,e individuals with ~ al evidence would :: -. onfounded by the __:L!llilCeOUS pneumo • . 2",- {hrough the gas . -:-. diatom-like par

Specificity

Liver

Kidney I 3 2 Bone Marrow

15 18

t Only studies with> 15 cases, all cases are non-drowning deaths §

+ = false positives, -

= true negatives

55


ticles (37) indicating that the hepatoportal circulation may contain diatoms due to the products of digestion. It is uncertain how particulate matter could entire the hepatoportal circulation which usually accepts soluble by simple diffusion or facilitate transport across cell membranes. However, for diatoms in the gastrointestinal tract to be a relevant source of diatoms in peripheral tissues requires a fantastic journey in the bloodstream. Diatoms in the hepatoportal circulation must progress through hepatic sinusoids and enter the inferior vena cava, progress to the heart, pass through the capillary bed in the lung, re-enter the heart, disseminate into the arterial system and become enlodged in a peripheral capillary bed. Throughout the enter process, the diatom must pass undetected by phago cytes, in the sinusoids (e.g. Kupffer cells), the pulmonary capillary bed, and a terminal capillary bed. If we accept that some diatoms may reach distant sites, such as the bone marrow, what is the significance of this for the diatom test? This question was anticipated by Timperman who indicated that the medicole gally significant diatoms in a tissue-extract were concordant with diatoms from the drowning medium. This concept was further articulated by Hendey (48): If the confusion and uncertainty under which the diatom test has laboured is to be dispelled it should be regarded in the following light. The diatom test for death by drowning must be able to show that the diatoms recov ered from the deceased person are part of the diatom flora taken at the site where the subject was lying or where the subject entered the water or was thought to have entered the water. On this basis, if diatoms ar~ occasionally found in the tissues of the non drowned it is of no relevance to the diatom test for drowning if the crite rion ofconcordance is rigidly applied. In fact, once this crtierion is applied the specificity and positive predictive value of the diatom test for drown ing using femoral bone marrow is similar that of routine diagnostic tests in clinical medicine (chapter 4). In summary, the possibility of the presence of diatoms in the tis sues of non-drowned people is the root of much of the criticism of the diatom test. This criticism is based on an imperfect understanding of the basic principles of the test and misconceptions about the significance of 56


- _..:l:. e . However, _:-::e of diatoms _ bloodstream.

- .:: ~seminate into _ _ capillary bed . .:..'"'=- ~te d by phago apiUary bed,

_ -. with diatoms - - ~ articulated by

; - - T he diatom . ~ :::jruo ms reeov - __ ~3.:'e n at the site

-.:: water or was

frustules in human tissue. On this basis, it is important to realize that a medicolegaUy important diatom test result not only demonstrates the pres ence of diatoms in tissue but also the same diatoms at the site of drown mg.

* 5. RESEARCH AND THE DIATOM TEST Since the classical studies, most research on diatoms and drowning has emphasized three main areas: 1. Studies with experimental models to test the validity of the diatom

test for drowning.

2. Development of novel methods to extract frustules from human tis

sue.

3. Development of different approaches to the quantitative and qualitia

tive analysis of diatoms in drowning.

Research with experimenta) animal models of drowning has facilitated further understanding of the fundamental events that occur in drowning, and represents the logical continuation of the original work of Incze. The search for alternative procedures for the acid digestion of tissue for frus tule extraction underlies most new laboratory methods. Finding different and meaningful ways of interpreting forensic diatom analysis is largely based on determining the significance of pulmonary diatoms in bodies recovered from water.

Experimental Models ~

_.: g if the crite :-:erion is applied .": : st for drown . - ;: diagnostic tests _ : roms in the tis .,. ~ri[icism of the _ .:=_ randing of the -i gnificance of

Two experimental models have developed to study the validity of the diatom test for drowning. Ranner et al have re-examined the fundamental principle of the diatom test for drowning using an animal model of drown ing to show that diatoms from the drowning medium are an important source of diatoms in the body (49). In an ingenious experiment, these investigators drowned rabbits in diatomaceous water after amputating one leg and ligating one renal artery. Quantitative analysis revealed that the diatom burden of the bone marrow and kidney increased after drowning indicating the hematogenous distribution of diatoms from the lungs . In a 57


similar model, Lunetta et al have demonstrated that diatoms in the drown ing medium perforate the alveolar-capillary barrier and enter the systemic circulation (50). These experiments show, for the first time, that drowning is the direct causal link between diatoms in drowning medium and those recovered from postmortem tissues.

Extraction of Frustules Several procedures have been developed to replace the original acid diges tion method for extracting frustules from human tissues. Most of the meth ods rely on alternative chemical or physicochemical (e.g. ultrasonic radia tion (51)) means to solubilize tissue. Methods that have been particularly useful are enzymatic digestion of tissues with proteases (10, 52) such as proteinase K. Strong anionic detergents such as sodium dodecyl sulphate and nonspecific tissue solubilizers (51) have also been shown to be effec tive for frustule extraction. Simple centrifugation is usually used to isolate diatoms from extracted tissue-suspensions. However, membrane filtration (53), and gradient centrifugation (11) have also been advocated. Although many methods have been suggested as alternatives to acid digestion there is no evidence for improved yield of frustules since few studies have directly compared methods. Little is known about the centrifugational properties of frustules, in particular, the centrifugal forces that gives optimal quantitative isolation. This may be relevant since small pennate diatoms may be more difficult to isolate, using differential cen trifugation, than larger genera such as Navicula.

Quantitative and Qualitative Diatom Analysis A new concept is emerging in forensic diatom analysis due, in large mea sure, to the research of Auer (54, 55). Until recently, the diatom test for drowning has been based mostly on qualitative characteristics including the presence and concordance of diatoms in tissues. Little attention has been given to the magnitude of the diatom-burden of tissues, or the signif icance of the inter-organ variance of the diatom load. This is particularly important in the context of diatoms recovered from lung since diatoms in this site may not, in all cases, originate from the drowning process. This has resulted in the concept of combined quantitative and qualitative diatom analysis in an effort to establish valid laboratory criteria for a positive

58


the drown .~. :he ystemic _ ±at drowning J ill and those lD

. J.:

~

~ ~ . . . g. -

acid diges . -,:-: of the meth _ . ~ onic radia \..-:1 particularly _' . -2) such as

ed to isolate ane filtration - : . ated. rernatives to .- :ru tules since --: ~\\ n about the • ~r ~rifu gal forces ,"r since small . z'erential cen _

n

diatom test. The basic concept underlying this approach to the diatom test is that diatoms recovered from tissues must be ecologically consisent with the environment of drowning (i.e. the qualitative factor; a variant of the criterion of concordance) , and that the diatom load of the lung and organs must be consistent with previous empirical experience (i.e. the quantitative factor). A corollary to the qualitative factor in the analysis is that it may be possible to identify the site of drowning provided that the diatom popula tion is not too homogeneous. Pachar & Cameron (56) substantially agree with this concept of combined quantitative and qualitative diatom analysis. In a recent study, these investigators found that a potential threshold level for a significant lung diatom burden may be - 15 diatoms per 100 gram of lung. In agree ment with Auer, this study found a correlation between the presence of diatoms in the pelipheral organs and in the lung, suggesting that the lung was the portal of entry for the diatoms (i.e., drow ning). Ludes (57, 58) has advocated further development of the ecologi cal aspects of the diatom by emphasizing the role of diatom community structure in the diagnosis of drowning. In a recent study, Ludes reported the results of comparing the diatom flora from continuous samples of rivers in France and drowning deaths in the same areas. There was a sig nificant correlation between the prevalence of specific genera in the river samples and tissue-extracts indicating the utility taxonomic inventories of diatoms. Unfortunately, in many large countries with extensive waterways the continuous monitoring of diatom flora is not feasible.

Use of Bone Marrow . . ~ . in large mea -:: _:arom test for .. ::c including

- ~ " rocess. This __ali tative diatom .:.! for a positive

Many different organs have been adovcated as starting material for frus tule extraction. The most obvious choice of organ to use as starting mate rial for simple qualitative diatom anlaysis is the lung. However, there are several problems with the lung as an index source for diatoms that have entered the body from drowning. It is theoreticaly possible for diatoms to enter the lung passively by percolation after death. In addition, the diatom burden may be quite large if the local fl ora is highly concentrated. This can lead to false positives if the burden exceeds an arbitrarily set threshold value. On this basis, the best tissue for frustule extraction would have the two characteristics: 59


1. Be perfused by blood that could, in principle, have just passed

through the pulmonary capillary bed.

2. Be immune to spurious postmortem contamination of diatoms from

the drowning medium.

The two tissues that fulfill each of these criteria are the blood in the pul monary viens or left heart if harvested with care in fresh bodies, or the bone marrow of an intact long bone (e.g. femur). Based on this reasoning, we have studied the utility of the femoral bone malTOW as a source of tis sue for the diatom test for drowning. This research in discussed in detail " in the next chapter.

* 6. REFERENCE 1.Schwar TG. Drowning. Its chemical diagnosis. A review. Forensic Sci 1972;1:411-417. 2. Foroughi E. Serum changes in drowning. Journal of Forensic Sciences 1971; 16(3):269-282. 3. Moritz AR. Chemical methods for the determination of death by drowning. Physiol Rev 1944;24:70-88. 4. Coutselinis A Boukis, D. The estimation of Mg2+ concentration in cerebrospinal fluid (C.S.F.) as a method of drowning diagnosis in sea water. Forensic Sciences 1976;7:109-11l. 5. Gettler AO. A method for the determination of death by drowning. J. Amer. Med. Assoc. 1921;77:1650-1652. 6. Kerr DJA Asphyxia. IIi: Forensic Medicine. Sixth ed. London: Adam and Charles Black, 1957: 157-158. 7. Piette M Timperman, 1., Parisis, N. Serum strontium estimation as a medico-legal diagnostic indicator of drowning. Med Sci Law 1989;29(2): 162-171 . 8. Azparren J de la Rosa, 1., Sancho, M. Biventricular measurement of blood strontium in real cases of drowning. Forensic Science International 1994;69: 139-148. 9. Amin MA Samia, AH., Kabil, M.A et al. Serum strontium estimation as a diagnostic criterion of the type of drowning in water. Forensic Science International 1985;28:47-52.

60


e blood in the pul .~ -h bodies, or the .) this reasoning, source of tis ~ ~u ssed in detail

--i e\ . Forensic Sci

_:: n of death by

r

- :; ncentration in ~ .iiagnosis in sea

: .. --. by drowning. J.

e=!. London: Adam

estimation as a \led Sci Law ~

:neasurement of :::orensic Science _':')Jtium estimation _ ::-. water. Forensic

10. Kobayashi M Yamada, Y, Zhang, W-D., Itakura, Y, Nagao, M., Takatori, T. Novel detection of plankton from lung tisue by enzymatic digestion method. Forensic Science International1993;60:81-90. 11. Terazawa K Takatori, T. Isolation of intact plankton from drowning lung tissue by centrifugation in a colloidal silica gradient. Forensic Science International 1980; 16:63-66 . 12. Incze G Tamaska, I., Ggyongyosi, J. A vizbefulas bizonyitasa aver es a szervek planktonvizsgalataval. Orv Hetil 1951 ;7: 1003. 13. Incze G Tamaska, L., Ggyongyosi, J. Zur blutplanktonfrage beim tod durch ertrinken. Dtsch Z Gasamt~ Gerichtl Med 1955;43:517-523. 14. Mikarni Y Kanda, M., Kamimura, 0., Okuyama, M. Experimental study and practice on the detection of vegetative planktons in the bone marrow of the drowned dead body. Acta Med Okayama 1959;13:259 268. 15. Golaeff DA. Use of phyto-plankton method for differentiation between drowned persons and bodies thrown into water. Odessky Med J 1928;3:425-430. 16. Merkel H. Plankton findings in lungs of drowned persons and their practical significance. Deutsche Ztschr.f.d.ges. Gerichtl. Med. 1939;31:211-212. 17. Tomonaga T. Demostration of plankton in organs of drowned persons. Jap.1. Med.Sci., VII, Social Med.and Hyg. 1940;3:197-198. 18. Karkola K Neittaanmaki, H. Diagnosis of drowning by investigation of left heart blood. Forensic Sciences International 1981; 18: 149-153. 19. Chardez D Lambert, 1. Protozoaires cilies et thanatologie. Forensic Science International 1985;28:83-101. 20. Spitz WU. Drowning. In: Spitz WU Fisher, R.S., ed. Medicolegal Investigation of Death, Guidelines for the Application of Pathology to Crime Investigation. Springfield, Illinois: c.c. Thomas, 1973: 21. Peabody AJ. Diatoms and Drowning - A Review. Medicine, Science, and the Law 1980;20(4):254-261. 22. Revenstorf V. Der nachweis der aspirierten ertrankungs flussigkeit als kriterium des todes durch ertrinken. Vierteljahresschs Geritchtl Med Off Sanitaetswes 1904;28:274-279 _ 23. Incze G Gyongyosi, 1. Wirkung des wasserdrucks auf die postmortale flussigkeitstromung in die luftwege. Acta Morphol Acad Sci Hung 61


1955;5:349-353. 24. Incze G . [Phytoplankton resorption in drowning] . Acta M orphol Hung 1951; 1:421-430. 25. Incze G. Fremdkorper in blutkreislauf ertrunkener. Zentralbl AUg Pathol Anat 1942;79: 176. 26. Tamaska L. [Diatom content of bone marrow in corpses in water]. Orv Hetil 1949;16:509-511. 27. Tamaska L. (On diatom demonstration in the bone marrow of drowned dead bodies]. Deutsche Z. Ges. Geric htl. Med. 1961 ;51 :398-403 . 28. Mueller B. [On the problems of the occurence of diatoms in the organs of cadavers not having lain in water] . Deutsche Z. Ges. Geric htl. Med. 1963 ;54:267 -272. 29. Mueller B. Zur frage des vorkommens von diatomeen in organen von leichen, die nicht in wasser gelegen haben. Dtsch Z Gesamte Gerichtl Med 1963 ;54:267-272. 30. Mueller B Gorgs, D. Studien uber das eindringen von corpiscularen wasserbestandteilen aus den lungenalveolen in des kreislauf wahrend des ertrinkungsvorganges. Dtsch Z Gesamte Gerichtl Med 1949;39:715-725. 3l. Thomas F Van Hecke, W., Timperman, 1. The detection of diatoms in the bone marrow as evidence of death by drowning. Journal of Forensic M edicine 1961 ;8(3): 142-144. 32. Thomas F Hecke, W ., Timperman, J. Death by drowning - a problem of forensic medicine. Ciba Sympos 1961;9:154- 16l. 33. Thomas F Van Hecke, W., Timperman, 1. The medicolegal diagnosis of death by drowning. Journal of Forensic Science 1962;7(1): 1- 14. 34. Thomas F Heeke, W., Timperman, 1. Diagnostic medi co-legal de la mort par submersion par la mise en evidence de diatomees dans la moelle des os longs. Ann. Med. Leg. 1962;42:369-373. 35. Timperrnan 1. The detection of diatoms in the maITOW of the sternum. Journal of Forensic Medicine 1962;9(4): 134-136. 36. Timperman 1. Observations on the diatom question. Dtech Gesamte Gerichtl Med. 1968;63(2): 127-128. 37. Timperman 1. Medico-legal problems in death by drowning: Its diag nosis by the diatom method . Journal of Forensic Medicine 1969; 16(2):45-75.

62


\lorphol Hung

""s in water]. Orv ~ow of drowned . : ~ :398-403. ~ - in the organs . Gerichtl. Med.

--. ' n organen von G;:-amte Gerichtl

02

\.2 n corpiscularen cei lauf wahrend Gerichtl Med

n of diatoms in

ng. Journal of

...

~~egal

diagnosis of __ :- 1):1-14. di o-legal de la J[omees dans la

-= : of the sternum. ~ . _.

Dtech Gesamte

ning: Its diag : _:-e ic Medicine _ _ - l,

38. Calder YM . An evaluation of the diatom test in deaths of professional divers. Med Sci Lwa. 1984;24(1):41-46. 39. Koseki T. Investigations on the bone marrow as a material in the diatom method of diagnosing death from drowning. Acta Med BioI 1969; 16(2):85-90. 40. Neidhart DA Greendyke, RM. The significance of the diatom demon stration in the diagnosis of death by drowning. American Journal of Clinical Pathology 1967;18(4):377-382 . 41. Schneider V. Versuch einer wertung der diatmeenprobe. Dtsch Z Gesamte Gericht Med 1969;26:92-96 . 42. Schneider Yea. [On the determination of radioactively labeled diatoms in the organs]. Beitr Gerichtl Med 1969;25:158-164. 43. Schneider V. Evaluation of the diatom test. Beltr Gerichtz Med 1969;26:92-99. 44. Schellman B Speri, W. Diatmeen-nashweis im knochenmark (femur) nichtertru nkener. Z Rechtsmed 1979;83:319-324. 45. Porawski R Investigati~n on the occurrence of diatoms in organs in deaths from various causes. Journal of Forensic Medicine 1966; 13(4): 134-137. 46. Foged N. Diatoms and drowning - Once more. Forensic Science International 1983;21:153-159. 47. Dayan AD Morgan, R.J.T., Trefty, RT., Paddock, T.B.B. Naturally occurring diatomaceous pneumoconiosis in sub-human primates. J Comp Pathol 1978;88:321-325 . 48. Hendey NI. Letter to the Editor, Diatoms and Drowning - A Review. Medicine, Science, and the Law 1980;20(4):289. 49. Ranner G Juan, R , Udermann, R [On the evidential value of diatoms in cases of death by drowning]. Z Rechtsmed 1982;88(1-2):57-65. 50. Lunetta P Penttila, A. Scanning and transmission electron microscopic evidence of the capacity of diatoms to penetrate the alveolar-capillary barrier in drowning. International Journal of Legal Medicine 1998;in press. 51. Fukui Y Takahashi, S., Matsubara, K. A new method for detecting diatoms in human organs. Forensic Science International 1980; 16:67 74. 52. Ludes B Quantin , B., Doste, M ., Mangin, P. Application of a simple 63


enzymatic digestion method for diatom detection in the diagnosis of drowning in putrified corpses by diatom analysis. lnt J Legal Med 1994; 107( 1):37-41. 53. Funayama M Aoki, Y, Sebetan, I.M., Sagisaka, K. Detection of diatoms in blood by a combination of membrane filtration and chemi cal digestion. Forensic Science lnternational1987;34:175-182. 54. Auer A. Qualitative diatom analysis as a tool to diagnose drowning. American Journal of Forensic Medicine and Pathology 1991; 12(3):213-218. 55. Auer A Mottonen,M. Diatoms and drowning. Z Rechtsmed 1988; 10 1(2):87 -98. 56. Pachar JV Cameron, J .M. The Diagnosis of Drowning by the Quantitative and Qualitative Analysis of Diatoms. Medicine, Science, and the Law 1993;33(4):291-299. 57. Ludes B Coste, M . D.iatomees et medecine legale.Paris: Tec & Doc Lavoisier Editions Medicales lnternationale, 1996 58. Ludes B Coste, M. Tracqui, A., Mangin, P. Continuous river monitor ing of the diatoms in the diagnosis of drowning. Journal of Forensic Science 1996;41 (3):425-428.

64

.~

diagnosis of

1:- : J Legal Med

~-.

Detection of -~.:. jon and chemi , ~ 75-182. ~3 se drowning . .:..!1d Pathology Z Rechtsmed wning by the

;; river monitor ;: _mal of Forensic

4 . Validity and utility of the diatom test using bone marrow The quantitative aspects of the utility and validity of the diatom test for drowning using femoral bone marrow are now described. The basis for the present description is the quantitative analysis of cases (n = 771) processed for the diatom test for drowning at the Office of the Chief Coroner for Ontario between 1977-1993. Most cases were drownings recovered from water in Ontario, Canada"; therefore, the results can be reasonably extrap olated to most temperate freshwater environs. In the analysis that follows, the outcome of the diatom test for drowning is correlated with the site, sea son, and month of drowning to induce ecological factors that influence test outcome. Bone marrow from intact femora (or rarely, an intact kidney) was used for the extraction of diatoms using the method of Timperman with minor modifications as described in the next chapter. Full description of the studies summarized in this chapter can be found elsewhere (1, 2). The data presented is based on the belief that use of femoral bone marrow as a staring material for the extract of diatoms is the most reliable. Reasons for this have been described in the previous chapter, but it is important to reiterate some of the basic characteristics that make bone marrow a scientifically preferred specimen for the extraction of diatoms. The main advantage of bone marrow over, for example, lung tissue is that the diatoms in the marrow must have derived from the hematogenous dis semination of particles from the lung requiring a functioning heart. Lung 65


tissue may become laden with diatoms by passive percolation in the post mortem period if the body is submerged in water. Of course, this does not exclude the possibility that some of the diatoms recovered from lung tis sue may have originated from drowning.

* 1. UTILITY OF THE DIATOM TEST Outcome Ratios for the Diatom Test One way of determi ning the medicolegal value of the diatom test for drowning is to show, in a relevant population of cases (e.g. a group of puta tive drowning cases), that this test may be helpful as an ancillary method to determine if drowning was the cause of death. We can describe this quantitatively as the utility of the test, defined as the ratio of the nu mber of all positive test results to the sum of all positive and negative test out comes. This ratio represents the frequency of a positive test outcome in the relevant forensic population. The utility of the diatom test for drowning using femoral bone marrow was calculated in a series of 771 cases of drowning that occurred during the summer, late spring and early autumn (Fig. 4.1 & Table 4. 1) in Ontario, Canada. The diatom test for drowning was positive in 205 cases (28 %) of the fres hwater drowning cases but was rarely positive if drown ing occurred in water from a domestic source that lacked diatoms due to water filtration and processing (Table 4.2). Only four cases (12%) of domestic drownings had a positive diatom test. Drowning medium was available for analysis in two of these cases, and diatoms were found in both cases. The diatoms were derived from an abrasive cleaning agent in one case and from gravel added into the water in the other case.

Seasonal and Monthly Variation of Diatom Test Outcome There was a conspicuous monthly variation in the incidence of a positive outcome of the diatom test (Fig. 4.2). The diatom test was most likely to be positive in April (-40%), July (-40%), and November (-30%) and least likely to be positive in the Winter months. However, the pattern correlated with the well documented monthly variation in diatom population due to cyclic diatom blooms. The principal diatom blooms occur in early spring and autumn with a sharp decline in the live diatom population between the

66

Validity and Utility of Diatom Test

: _:!on in the post . this does not -: ~ from lung tis-

diato m test for ;: ;. ..1 group of puta ~_ ciliary method ~ ~..n describe this of the number - ~ ~=gat ive test out • _~ - . outcome in the

TABLE4 . J Outcome of th e Diorom Testfor DrOlV/zillg by Seasoll

Season

Number of Drownings J

Number of Positive Tests 2

Winter

13 8177 1 ( 18 ';()

26/138 ( J9 ';()

Spring

1721771 (22';()

431172 (257(')

Summer

2931771 (387()

93/293 (32o/()

Autumn

168177 J (227()

431168 (257c)

J

",. = femoral bone

- . . . g that occurred

- . _ - Table 4.1) in

.:...ve in 205 cases

sitive if drown

-=.:! diatoms due to -:- ..z ::ases (12%) of ng medium was were found in

eaning agent in -:-". -" ~ case.

Indica tes the number and proportion of drowning compared with the total series

2 Indica tes the number and proportion of positive diatom tests for alJ cases in the season

16 ,-------------------------------------------~

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en en 12 c

c

3:

e c '0 c 0

- ,::. • Outcome

8

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0

~

e of a positive - most likely to - ~ - 30%) and least ::: ~ ttero correlated - _ pulation due to ;:: _!" in early spring ~ _ .::.tiOD between the

0~

Q.

Jan Feb Mar Apr Ma y Jun Jul Aug Sep Oct Nov Dec Month 4.1. Relative proportion of drowning cases in various months for 771 cases of drowning in Ontario. Canada between 1977 and J993. 67


blooms. The high incidence of positive diatom tests in the summer months was presumably due to persistence of the insoluble frustules of the dead diatoms in water. Although the monthly variation of test incidence corre lated with diatom blooms, a basal concentration of diatoms in freshwater must have been maintained since seasonal variations deviated by only 13% from Winter (-19%) to Summer (-32%) (Table 4.1). The appearant monthly variation in the utility of the test has important implications for the validity of the test (section 2).

* 2. VALIDITY OF THE DIATOM TEST Concepts in Support of the Diatom Test The relationship of test outcome with diatom population dynamics is important corroborating evidence for the validity of the test since it is pre dictable that the diatom content of the water would influence test outcome. The correspondence of the high incidence of positive test outcomes with peak months of diatom blooms is consistent with the water concentration of diatoms being a key factor in test outcome. However, since diatom frus tules persist is freshwater throughout the year, drownings in months with suboptimal water concentration of diatoms still provide occasional posi tive test outcome, although at a lower overall rate. Other data support the reliability of the diatom test for drowning. For example, (i) the high false negative rate indicates that postive results, and therefore, false positives are infrequent; (ii) domestic water drownings had negative diatom tests unless the water contained diatoms derived from some external source (e.g. abrasive cleansers, contamination of the bath with diatoms from the out-of-doors environment); (iii) drowning in water with no or few diatoms (e.g. some samples of Winter water) gives a nega tive test result; and (iv) paired drownings in the same body of water had the same diatom species in the bone marrow. Some additional features (discussed below) also support the valid ity of th diatom test. This includes th fact that diatoms extracted from femoral bone marrow in cases of drowning represent a distinct subset of freshwater diatoms that conform to certain size and shape criteria . Evaluated together these data provide evidence in support of the utility and reliability of the diatom test for drowning. The data suggest that a positive

68

Validity and Utility of Diatom Test

. --e ~ u mmer months ~_ -_ le s of the dead :: :!1 idence corre

in freshwater

_ ( d by only 13% - ~ . The appearant ::: :m plications for

TABLE 4.2 Outcome of the Diotol11 Test for Drowning by Site ofDrolVning Outcome Site of drowning

Total

Positive

Negative

Naturally-occuring body of water!

738

205 (28%)

533 (72%)

33

4 (12%)

29 (889C)

771

209 (279C)

562 (73%)

Bathtub. pool. or toilet

__..;.:~o n dynamics is -e :e-[ since it is pre :- _c:: ~ e test outcome. :=: :;:~t outcomes with _cr concentration :

Forensic Diatomology and Drowning

Forensic Diatomology and Drowning

Drowning World

Drowning Ruth

Man Drowning

Drowning Rose

Man Drowning

The Drowning

Drowning World

Drowning Rose

Drowning Lessons

Drowning Mermaids

Drowning Towers

Drowning Ruth

Drowning World

Man Drowning

Drowning World

The Drowning

Drowning Ruth

Drowning World

Drowning World

Drowning Mermaids

drowning ruth

Man Drowning

Drowning Rose

Drowning Ruth

Drowning World

Drowning World

Fear Of Drowning

An Ordinary Drowning

The Drowning House

Forensic Diatomology and Drowning