Introduction
Persistent Organic Pollutants are carbon-based chemicals that exhibit characteristics such as, for example, that they do not break down under environmental conditions, are semi-volatile, have low solubility in water, and have an inherent toxicity. The combination of these chemical and physical properties results in long-range transport and in bioaccumulation of the substances. Consequently, POPs are found in regions far from where they have been used or released. Due to their lipophilicity and persistence, they accumulate in the food-chain and high concentrations have been detected in animals and humans. Acronyms such as PBTs (persistent bioaccumulative and toxic substances), PTS (persistent toxic substances) or PEPs (persistent environmental pollutants) have also been used interchangeably. In a narrower sense, the term “POPs” refers to twelve chemicals addressed in the Stockholm Convention on Persistent Organic Pollutants, a global treaty negotiated under the auspices of the United Nations Environment Programme (UNEP) in order to eliminate the production and use or release of POPs. The twelve “Stockholm” POPs are the ten intentionally produced chemicals aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, toxaphene, hexachlorobenzene, and polychlorinated biphenyls (PCB), and the two unintentionally produced substances polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF)1. The Stockholm Convention has as its objective the protection of human health and the environment from POPs. The process of developing the treaty was initiated in May 1995 by UNEP leading to the adoption of the convention in May 2001 in Stockholm. One year later, 151 countries are signatories of the Stockholm Convention. The Convention will come into force after 50 ratifications. There is a high level of interest among governments, international organizations, environmental and industrial non-governmental organizations, and academia in addressing POPs issues in a concerted way and searching for solutions to problems caused by POPs. With a global convention in place, we may move forward to eliminate POPs, considered by some to be the most toxic man-made substances. This volume introduces the history and obligations of the Stockholm Convention as well as its provisions for adding more POPs in the future. It also covers the POPs Protocol under the Convention on Long-range Transboundary 1
The Convention also contains provisions for PCB and HCB as unintentionally produced substances.
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Air Pollution (LRTAP) of the United Nations Economic Commission for Europe. It addresses the Stockholm POPs and highlights their properties, toxicity, and occurrence in the environment and provides human data. Chapters are dedicated to global transport and the fate of POPs, inventories, and technical solutions for the reduction in POPs releases or their destruction. Case studies from three continents – Asia, Africa, and Central America – provide regional flavor and show that developing countries have been able to address this class of chemicals. The chapters were written by experts highly regarded for their knowledge of POPs issues; furthermore, they represent different perspectives. As POPs are global in their impact, this volume also attempts to cover a wider geographical range and different stages of industrial development. Châtelaine, September 2002
Heidelore Fiedler
CHAPTER 1
Protocol to the 1979 Convention on Long-Range Transboundary Air Pollution on Persistent Organic Pollutants: The 1998 Agreement for the UNECE Region Keith Bull United Nations Economic Commission for Europe, Palais des Nations, 1211 Geneva 10, Switzerland E-mail:
[email protected] The 1979 Convention on Long-range Transboundary Air Pollution provides a framework for detailed agreements on particular substances through Protocols to the Convention. The Protocol on Persistent Organic Pollutants was adopted by 36 Parties in 1998. So far, 6 countries have ratified the Protocol, another 10 need to do so before it enters into force. The Protocol was the culmination of work under the Convention started in 1989 and led initially by Canada and Sweden.An ad hoc Working Group under the Convention provided the necessary information and draft text for the negotiations. The adopted Protocol covers 16 substances or groups of substances that were selected by a screening procedure followed by negotiations. For most of the substances (aldrin, chlordane, chlordecone, DDT, dieldrin, endrin, heptachlor, hexabromobiphenyl, hexachlorobenzene, mirex, PCB, toxaphene) the obligation of Parties is for elimination of production and use; the substances are mainly pesticides with well-demonstrated persistence and toxicity. For three substances (DDT, HCH, PCB) there are restrictions of use, and for another group of substances (PAHs, dioxins/furans, and hexachlorobenzene) there are obligations to reduce emissions from specified reference years.A mechanism for selecting substances to add to the Protocol, through an amendment procedure included in the Protocol, was agreed separately in a Decision by the Executive Body for the Convention. Amendments are possible once the Protocol enters into force. Review procedures to ascertain the sufficiency and effectiveness of the obligations are included in the Protocol, the first such review is to be within three years of the Protocol entering into force. Keywords: Persistent organic pollutants (POPs), Protocol, Convention on Long-range Transboundary Air Pollution
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1 Introduction The 1998 Protocol on persistent organic pollutants (POPs) [1] was adopted by the Executive Body for the Convention on Long-range Transboundary Air Pollution on 24 June 1998 in Aarhus (Denmark). It was a regional agreement reached as a result of much negotiating effort. However, it was a major step towards a global agreement and provided the basis for further steps in the regional control of POPs in the future. The Convention has been the focus for international air pollution controls for the UNECE (United Nations Economic Commission for Europe) area over many years and has played an important role in the emission decreases observed in Europe and North America in recent years. This paper describes the Protocol, its content and obligations, within the perspective of the Convention and the UNECE. It seeks to describe the history of the development of the Protocol and indicate the way it will operate in the future.
2 The United Nations Economic Commission for Europe The UNECE is one of the five regional commissions of the United Nations. It includes countries of Western and Eastern Europe, including the Newly Independent States (NIS) extending eastwards to countries such as Kazakhstan and Kyrgyzstan. The region also includes, despite its name, the United States of America and Canada. Created in 1947 as a United Nations regional organization it struggled in its early days to bring together “East” and “West” in a spirit of cooperation. After a difficult initial period the UNECE played a vital role in providing the forum for discussions and agreement between countries with very different political and economic systems. Such a framework provided an important platform for launching agreements such as the Convention on Long-range Transboundary Air Pollution (CLRTAP). In turn, the Convention played an important role in promoting a spirit of collaboration on a specific issue which was recognized by many as one requiring international cooperation to solve effects at a national level. The UNECE secretariat, based in Geneva, provides the secretariat support for a number of multi-lateral environmental conventions, including that on longrange transboundary air pollution. Indeed CLRTAP identifies the secretariat role of the Executive Secretary of UNECE in its text (Article 11). Members of the secretariat support the work of the Executive Body of the Convention and its subsidiary bodies primarily through the organization of meetings and the preparation of documents. They also provide the necessary links with international organizations with common goals and interests.
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3 The Convention on Long-Range Transboundary Air Pollution The history of CLRTAP dates back to the 1960s when there was increasing concern about the effects of air pollution and it was suggested that long-range effects were possible. Links were drawn between emissions in Europe and effects on Scandinavian lakes. In 1972 a United Nations Conference on the Human Environment, held in Stockholm, initiated discussions aimed at international cooperation to address the effects of acidification. Throughout the 1970s scientific studies investigated the effects and their cause and clearly demonstrated that air pollutants could travel for considerable distances and could cause harmful effects thousands of kilometres away from the emission sources. The transboundary nature of the problem could only be solved by international agreement. It has been suggested that CLRTAP arose as the result of a specific “policy window” resulting from the convergence of Scandinavian concern for the issue and the will of the Soviet Union to find a more binding platform than that of the positive but less binding OECD [2]. The Convention [3] was adopted in Geneva in 1979 and entered into force in 1983 after ratification by 16 Parties. The Convention identifies the general principles for international cooperation on air pollution abatement and provides an institutional framework for bringing together science and policy. It provides no specific commitment to decrease or limit emissions of any air pollutant, but offers a binding legal framework within which specific agreements could be agreed. These agreements have taken the form of protocols to the Convention – enshrined in documents that have been separately adopted and ratified by Parties to CLRTAP. Thirty-three Parties (including the European Community) signed the Convention in 1979. Most of these signatories have now ratified the agreement and several other countries of the UNECE region have acceded to the Convention.As a result there are currently 48 Parties (and two signatories that are not Parties) to the Convention (listed in Table 1), from a total of 55 UNECE states. Non-Parties generally fall into two categories, namely some countries from Eastern Europe (e.g., Uzbekistan) and some of the smallest states in Europe (e.g.,Andorra). Since its entry into force CLRTAP has been extended by eight protocols. Five of these [3] have themselves already entered into force having received at least the necessary number (16) of ratifications: – The 1984 Protocol on Long-term Financing of the Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP); – The 1985 Protocol on the Reduction of Sulphur Emissions on their Transboundary Fluxes by at least 30 per cent; – The 1988 Protocol concerning the Control of Nitrogen Oxides or their Transboundary Fluxes; – The 1991 Protocol concerning the Control of Emissions of Volatile Organic Compounds or their Transboundary Fluxes; – The 1994 Protocol on Further Reduction of Sulphur Emissions.
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Table 1. Status of the 1998 Aarhus Protocol on Persistent Organic Pollutants (POPs) – June 2002
Signature Armenia Austria Belarus Belgium Bosnia and Herzegovina Bulgaria Canada Croatia Cyprus Czech Republic Denmark Estonia Finland France Georgia Germany Greece Holy See Hungary Iceland Ireland Italy Kazakhstan Kyrgyzstan Latvia Liechtenstein Lithuania Luxembourg Malta Monaco Netherlands Norway Poland Portugal Republic of Moldovia Romania Russian Federation San Marino Slovakia Slovenia Spain Sweden Switzerland The former Yugoslav Republic of Macedonia Turkey Ukraine United Kingdom of Great Britain and Northern Ireland United States of America Yugoslavia European Community Total:
Ratification
18.12.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998
05.12.2001 18.12.1998
06.07.2001
24.06.1998 24.06.1998 24.06.1998 24.06.1998
25.04.2002
18.12.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 24.06.1998 25.06.1998 24.06.1998 24.06.1998
01.05.2000 23.06.2000 16.12.1999
19.01.2000 14.11.2000
24.06.1998 24.06.1998 24.06.1998 24.06.1998 36
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The remaining three protocols, including the 1994 Protocol on Persistent Organic Pollutants, still await further ratifications before they enter into force: – The 1998 Protocol on Heavy Metals; – The 1998 Protocol on Persistent Organic Pollutants (POPs) and; – The 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone. Over the years, protocols have become increasingly complex, with increasing amounts of technical information provided (usually in the forms of annexes to the protocols) to guide Parties in their implementation of each protocol. Early protocols, whilst recognizing that environmental and human health effects were important and needed to be addressed, defined obligations in simple terms; percentage emission decreases, or a return to previous emission levels, sought to alleviate the effects of air pollutants, but did not link obligations to environmental goals. Through the 1990s, however, more attention has been paid to the effects of air pollutants. For two protocols, the 1994 Protocol on Further Reduction of Sulphur Emissions and the 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone, effects-based approaches, using critical loads [4] and integrated assessment models [5] have defined Parties obligations by taking account of national emissions, their effect on the environment, and the costs involved in achieving certain environmental goals. While neither the 1998 Protocols on Heavy Metals nor that on POPs take an effects-based approach, as is the case for “first Protocols” for other air pollutants, they both pay careful regard to the effects of the pollutants whose controls they encompass.
4 Steps Towards Development of a Protocol on Persistent Organic Pollutants This section outlines the history of the development of the Protocol on POPs. For a more comprehensive description of events and a discussion of the factors important for the development and final form of the protocol see Selin [6]. The Convention’s attention was first drawn to the issue of POPs by the Canadian delegation to the Working Group on Effects in 1989.An official of the Canadian Department of Indian and Northern Affairs presented a paper with the approval of Environment Canada, the body responsible for the Canadian delegation at CLRTAP meetings. The Swedish government had similar concerns and, in 1990, the Working Group on Effects received a further paper for its attention from Canada together with a proposal from Sweden for the creation of a Task Force on complex organic compounds. Subsequently, in November 1990, the Executive Body of the Convention agreed to establish an intergovernmental Task Force on Persistent Organic Pollutants to be jointly led by Canada and Sweden. The Task Force was to work under the auspices of the Working Group on Technology and in cooperation with the Working Group on Effects. The Task Force first met in March 1991.
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The Task Force on POPs was given the job of assessing the effects of POPs and the possible need for action to control them. The Task Force set about compiling the necessary scientific information to prepare a substantive report on POPs. The lead countries were also able to take the opportunity to promote their interests and concerns to other Parties to the Convention. At the end of 1993, the Executive Body requested the Task Force to prepare a final report for its session at the end of 1994. The draft report was presented for discussion to a joint meeting of the Working Group on Technologies and the Working Group on Effects. It was received enthusiastically and recommended to the Executive Body. A similar report, from a Task Force on Heavy Metals, was treated similarly. The Executive Body deliberated upon future actions on both POPs and heavy metals and decided to set up an ad hoc Preparatory Working Group for each of the groups of pollutants. In this way the Executive Body did not commit itself to future action but provided the opportunity for further discussions and preparations to aid the decision-making process regarding future action. Further, the working groups were to report to the Working Group on Strategies which took the discussions into a more policy-oriented forum. The mandate of the Preparatory Working Group was to consider an initial list of substances and control options, consider and assess possible elements for a future protocol, and develop procedures for the future addition of substances to such a protocol. It was not a negotiating group but it did take steps to prepare documents for future consideration by the Working Group on Strategies that was charged with preparing a draft protocol and begin negotiations when there was a sound basis for doing so. The work-plan of the Preparatory Working Group, adopted in 1995, required it to prepare an annotated outline of a protocol and elements for a draft text, identify criteria for selecting an initial list of substances and developing proposals for adding substances to the list, as well as options for annexes and for a basic obligations article for a protocol. It was also expected to prepare, assemble and review information, hold technical workshops and assess implications of draft commitments. To arrive at a list of substances the Preparatory Working Group adopted a screening procedure. It considered a number of such procedures used by countries and by other bodies but also took into consideration the scope of the Convention regarding long-range transport. The three stages to the assessment involved: 1. Evidence of persistence (low vapour pressure, half life in the atmosphere of more than two days, low biodegradability (less than 30% in 28 days; OR monitoring evidence in remote regions); 2. Prioritization scoring based on bioconcentration factors or octanol/water partition coefficients and mammalian or aquatic toxicology; 3. Risk assessment. One hundred and seven POPs were considered and 87 remained after the first stage. For the second stage a scoring system was used to combine information on toxicity with that on bioaccumulation. For some substances data were not sufficient, but at this stage 36 substances were eliminated and 32 forwarded to stage 3. Through consideration of the scientific criteria, including properties such as the
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Table 2. List of fourteen substances arrived at through the ad hoc Preparatory Working Group on POPs screening procedure, and the four borderline substances included for additional consideration (in parentheses)
Pesticides
Industrial chemicals
Unintentional by-products
Aldrin Chlordane DDT Dieldrin Endrin Hexachlorobenzene Mirex Toxaphene (Chlordecone) (Lindane) (Heptachlor)
Hexabromobiphenyl PCB Pentachlorophenol (Short-Chain Chlorinated Paraffins)
Dioxins Furans PAHs
risks from degradation products, together with more socio-economic issues such as use, production and emissions resulting from these, a risk assessment was made of each substance. The methodology resulted in a list of just 14 substances (Table 2). Following subsequent discussions and proposals in the Preparatory Working Group, the list of 14 together with another four “border-line” substances (SCCP – short-chain chlorinated paraffins, heptachlor, chlordecone and lindane) was put forward for negotiations to the Working Group on Strategies. In setting the work-plans for the Preparatory Working Group and for the Working Group on Strategies, the Executive Body stressed the importance of rapid agreement on a protocol of limited scope, particularly in view of the model that such a protocol would set for action beyond the region and/or at a global level. This was with a view to aiding the development of a global agreement on POPs that had been started under the auspices of UNEP. It was recognized that some mechanism was likely to be required for adding substances to the lists that would be annexed to the final protocol. For this it was decided that the Executive Body would make a formal decision on the process drawing upon the experience gained in the screening and evaluation exercise used for drawing up the original list. The option for a Decision provided greater flexibility than incorporating the technical assessment procedures for amendment in the protocol itself, though the formalities for proposing new substances were considered as an article for the protocol. Through the subsequent five negotiating meetings in 1997 and 1998, not only the text, but also the lists of substances to be covered by the protocol were re-considered and individual substances negotiated for inclusion or exclusion. While many substances received consensus for inclusion, others were the subject of negotiations throughout 1997 and into 1998. The final negotiating session took place in February 1998, and sought to resolve such issues as the formal definition of PCB, possible DDT and HCB exemptions and the inclusion or exclusion of pentachlorophenol and SCCP. It agreed on the final list of 16 substances, or
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Table 3. Substances listed in the annexes to the 1998 Protocol on POPs
Annex I. Substances scheduled for elimination of production and use Aldrin Chlordane Chlordecone DDT (pp¢-dichlorodiphenyltrichloroethane) Dieldrin Endrin Heptachlor Hexabromobiphenyl Hexachlorobenzene Mirex PCB (polychlorinated biphenyls) Toxaphene Annex II. Substances scheduled for restrictions on use DDT HCH (hexachlorocyclohexane) PCB Annex III. Substances for which emissions must be reduced PAH (polycyclic aromatic hydrocarbons) Dioxins/furans Hexachlorobenzene
groups of substances (Table 3) comprising eleven pesticides, two industrial chemicals and three by-products/contaminants. This session also considered the final wording of the Executive Body decision on adding substances to the Protocol once it had entered into force. At a special meeting of the Executive Body in March 1998, Decision 1998/2 was formally taken on “information to be submitted and procedures for adding substances into the Protocol”. On 24 June 1998, at the fourth Environment for Europe Ministerial Conference in Aarhus, Denmark the Executive Body adopted the Protocol.
5 The 1998 Aarhus Protocol on POPs The Aarhus Protocol follows the pattern of many other such protocols. Following a preamble and definitions article, the objective and basic obligations are spelled out. Article 4 then specifies exemptions to the basic obligations. Articles 5 to 9 deal with the operational, technical and scientific issues: exchange of information and technology; public awareness; strategies, policies, programmes, measures and information; research, development and monitoring; and reporting. The introduction of public awareness into the Protocol was consistent with the adoption of the Aarhus Convention on Access to Information, Public Participation in Decision Making and Access to Justice in Environmental Matters at the same Ministerial Conference in 1998.Articles 11 and 12 deal with compliance and settlement of disputes, and Article 13 formally identifies the Annexes. Articles
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14 to 20 identify the formalities of: amendments; signature, ratification, acceptance and accession; depository; entry into force; withdrawal; and authentic texts. The basic objective of the Protocol (Article 2) is to control, reduce or eliminate discharges, emissions and losses of persistent organic pollutants. For this, the Protocol clearly adopts the precautionary principle referring to Principle 15 of the Rio Declaration on Environment and Development (Agenda 21) where it was identified. Principle 15 states that “lack of full scientific consensus shall not be used as a reason for postponing cost-effective measures to prevent environment degradation” where “there are threats of serious or irreversible damage”. To meet the objective, basic obligations under the Protocol are detailed (Article 3). They specify the need to take effective measures to eliminate the production and use of substances listed in Annex I (Table 3). Some substances are banned outright (aldrin, chlordane, chlordecone, dieldrin, endrin, hexabromobiphenyl, mirex and toxaphene). Others have specified exemptions but are scheduled for elimination at a later stage (DDT, heptachlor, hexaclorobenzene, PCBs). Disposal or destruction of these substances, or their transboundary movement, must be undertaken in an environmentally sound manner. The obligations take note of the existing Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal. The Protocol severely restricts the use of DDT, HCH (including lindane) and PCBs, substances listed in Annex II of the Protocol (Table 3). It also obliges Parties to reduce their emissions of dioxins, furans, PAHs and HCB, substances listed in Annex III to the Protocol (Table 3), below their levels in 1990 (or an alternative year between 1985 and 1995). For the incineration of municipal, hazardous and medical waste, it lays down specific limit values for these substances. Other timescales, listed in Annex VI, determine the need for action to apply best available technology (BAT), achieve limit values, and take effective measures to control emissions from mobile sources as indicated in Annexes V, IV and VII, respectively.
6 The Status of the Protocol At the adoption of the Protocol, 33 Parties to the Convention, including the European Community, signed the agreement. Spain became the 34th Signatory one day later, and over the following 6 months when the Protocol was open for signature Armenia and Hungary also signed. Since 1998, the Protocol has been ratified by six signatories (Table 1). These have completed their necessary national procedures and have lodged their articles of ratification with the United Nations. Under Article 18 of the Protocol, entry into force takes place on the ninetieth day following the sixteenth ratification. The Protocol then becomes binding on those Parties that have ratified. It will also become binding on all those that subsequently ratify or accede (the ratification process for non-Signatories) to the Protocol. It is usually takes some period of time, two or more years, for a Party to complete its national procedures towards ratification. While procedures vary from country to country they usually involve detailed consideration of obligations,
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often involving more than one government ministry, and a formal decision to ratify by government. Even so, the rate of ratification has been slow, and there are more ratifications of the Protocol on Heavy Metals that was adopted at the same time by the Executive Body. It is known that some countries have decided to delay ratification of the Protocol until completion of the negotiations on the global POPs Convention. There have been indications that the ratification of the two agreements would be considered in parallel to make most efficient use of national resources. This is likely to slow ratification and entry into force as the global Convention, drawn up under the auspices of UNEP, has only recently been adopted in May 2001 [7].
7 The Future – Implementation and Revision of the Protocol Once the Protocol enters into force there will be an obligation on Parties to the Protocol to report their usage and/or emissions of the substances listed. Already the Cooperative Programme on Monitoring and Assessment of the Long-Range Transmission of Air Pollutants (EMEP), that operates under the Convention, has taken steps to initiate reporting procedures. Some countries are already providing the required information. The Convention will monitor progress in implementation of the Protocol through the activities of its Implementation Committee in conjunction with the annual reporting procedures. In addition, Parties to the Convention are invited, every two years, to report on the strategies and policies they have adopted to meet obligations under the protocols to the Convention. This information too is scrutinized by the Implementation Committee, together with any direct submissions to the committee from individual countries. Under the terms of the Protocol a formal review of its obligations and consideration if they are still sufficient must be conducted within three years of entry into force. This provides the opportunity to update or amend the obligations, exemptions and annexes of substances. Amendments to the Protocol are dealt with under Article 14, though the procedure for adding substances is detailed in the Executive Body’s Decision 1998/2 [8]. In this, the technical screening procedure and provision of information to substantiate addition of a substance is described. While such a procedure can only take place after the Protocol has entered into force, the Executive Body in 1999 agreed to establish a group of experts on POPs, reporting to its Working Group on Strategies, that was charged with gathering and evaluating information on substances that might be added to the Protocol annexes. The expert group may also be able to provide advice for the review process when the Protocol enters into force. It remains to be seen what role the Protocol will play in the future controls of POPs now that the global POPs Convention has been adopted. While the substances and provisions of the two instruments are similar, the Protocol has additional substances and fewer exemptions. It might therefore be seen as leading the way for more stringent global controls in the future. In addition, it is likely
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that the Protocol will enter into force sooner and provide the opportunity to add more substances at an earlier date. This again will set a precedent for the global instrument to follow.
8 References 1. United Nations (1998a) Protocol to the 1979 Convention on Long-Range Transboundary Air Pollution on Persistent Organic Pollutants. ECE/EB.AIR/60 2. Castells N (1999) International environmental agreements: institutional innovation in European transboundary air pollution policies. PhD Thesis, University of Amsterdam 3. United Nations (1996) 1979 Convention on Long-Range Transboundary Air Pollution and its Protocols. United Nations: New York and Geneva 4. Bull KR (1995) Critical loads – possibilities and constraints. Water, Air and Soil Pollution 85:201–212 5. Hordijk L (1995) Integrated assessment models as the basis for air pollution negotiations. Water, Air and Soil Pollution 85:249–260 6. Selin H (2000) Towards International Chemical Safety: Taking Action on Persistent Organic Pollutants (POPs). Linköping. Linköping Studies in Arts and Science 211 7. UNEP (2001) Text of the Stockholm Convention on Persistent Organic Pollutants. UNEP/POPS/CONF/2. 8. United Nations (1998) Executive Body Decision 1998/2 on information to be submitted and the procedure for adding substances to Annexes I, II or II to the Protocol on Persistent Organic Pollutants. EB.AIR/WG.5/52, Annex II
CHAPTER 2
The Development of a Global Treaty on Persistent Organic Pollutants (POPs) John Buccini Chair, UNEP Intergovernmental Negotiating Committee on POPs, 31 Sycamore Drive, Ottawa, Ontario, Canada K2H 6R4 E-mail:
[email protected] This chapter summarizes the process involved in developing the recent United Nations Environment Programme (UNEP) treaty on POPs (the Stockholm Convention), summarizes the main provisions of the Convention, and briefly comments on the near-term prospects for further international developments on POPs. Keywords: Persistent organic pollutants, Stockholm Convention, Negotiation of convention
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The Mandate . . . . . . . . . . . . . . . . . Implementing the Mandate . . . . . . . . . Conclusions and Recommendations . . . . Actions in Support of the Negotiation Process The Negotiations . . . . . . . . . . . . . . .
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Abbreviations POPs UNEP UN ECE LRTAP USA DDT PCBs HCB GC IOMC IPCS IFCS WHA PIC INC SADC CEG COP ppm BAT BEP CAS IUPAC logKOW ENGOs IPEN
persistent organic pollutants United Nations Environment Programme United Nations Economic Commission for Europe Long-Range Transboundary Air Pollution United States of America 1,1¢-(2,2,2-trichloroethylidene)bis(4-chlorobenzene) polychlorinated biphenyls hexachlorobenzene Governing Council Inter-Organisation Programme for the Sound Management of Chemicals International Programme on Chemical Safety Intergovernmental Forum on Chemical Safety World Health Assembly prior informed consent Intergovernmental Negotiating Committee South African Development Community Criteria Expert Group Conference of Parties parts per million best available techniques best environmental practices Chemical Abstracts Number International Union of Pure and Applied Chemistry logarithm of the octanol/water partition coefficient environmental non-government organizations International POPs Elimination Network
1 Introduction Persistent organic pollutants (POPs) are organic compounds of natural or anthropogenic origin that possess a particular combination of physical and chemical properties such that, once released into the environment, they remain intact for exceptionally long periods of time as they resist photolytic, chemical and biological degradation. POPs in the environment are transported at low concentrations by movement of fresh and marine waters and, as they are semi-volatile, are transported over long distances in the atmosphere. The result is widespread distribution of POPs across the globe, including regions where they have never been used. POPs are characterized by low water solubility and high lipid solubility, resulting in their bioaccumulation in fatty tissues of living organisms, including humans, and they are found at higher concentrations at higher levels in the food chain. Thus, both humans and environmental organisms are exposed to POPs around the world, in many cases for extended periods of time spanning generations, resulting in both acute and chronic toxic effects to both humans and wildlife.
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In recent decades, the risks posed by POPs have become of increasing concern in many countries, resulting in actions to protect human health and the environment being taken or proposed at the national, regional and international levels. The following are some of the major regional and global initiatives that were underway prior to the formal commitment in 1997 to develop a global POPs treaty, and that were directed at identifying POPs and developing risk management measures to control the exposure of humans and the ecosystem to these substances. (a) The UNEP Global Programme of Action for the Protection of the Marine Environment from Land-based Activities was agreed to at a UNEP conference in Washington, D.C. (October 23–November 3, 1995) and POPs were identified as a priority for action under the plan. (b) The UN ECE Convention on Long-Range Transboundary Air Pollution (LRTAP) includes the Aarhus Protocol on POPs, which was signed on June 24, 1998, and calls for action on sixteen identified POPs. (c) The 1992 Convention on the Protection of the Marine Environment of the Baltic Sea (the Helsinki Convention). (d) The 1976 Convention for the Protection of the Mediterranean Sea Against Pollution (Barcelona Convention), as amended in 1995. (e) The North American Commission for Environmental Cooperation passed Resolution #95-5 on the Sound Management of Chemicals (October 13,1995) and gave immediate priority for Canada, Mexico and the USA to address persistent toxic substances and has resulted in the development and implementation of continental actions plans for DDT, chlordane and PCBs and a commitment to develop an action plan on dioxins, furans and hexachlorobenzene (HCB). (f) Canada-USA Great Lakes Water Quality Agreement (1972), including the Binational Toxics Strategy (April 1997), emphasizes action on POPs as well as other persistent toxic substances. While this list is not exhaustive, it does show that POPs were and will continue to be the subject of considerable attention for both scientists and policy makers.
2 Developing a Global UNEP Convention on POPs 2.1 The Mandate
At its May 1995 meeting, the UNEP Governing Council (GC) adopted Decision 18/32 on POPs, which invited the Inter-Organization Programme for the Sound Management of Chemicals (IOMC), working with the International Program on Chemical Safety (IPCS) and the Intergovernmental Forum on Chemical Safety (IFCS), to initiate an expeditious assessment process, initially beginning with twelve specified POPs [PCBs, dioxins, furans, aldrin, dieldrin, DDT, endrin, chlordane, hexachlorobenzene (HCB), mirex, toxaphene and heptachlor].As specified
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in the following text taken from Decision 18/32, this assessment process should, taking into account the circumstances of developing countries and countries with economies in transition: “a) consolidate existing information available from IPCS, UN ECE and other relevant sources, on the chemistry and toxicology of the substances concerned (particularly the impact on human, plant and animal health); b) analyze the relevant transport pathways and the origin, transport and deposition of these substances on a global scale; c) examine the sources, benefits, risks and other considerations relevant to production and use; d) evaluate the availability, including costs and effectiveness, of preferable substitutes, where applicable; and e) assess realistic response strategies, policies and mechanisms for reducing and/or eliminating emissions, discharges and losses of POPs.” Based on the results of this process, together with the outcome of the UNEP Intergovernmental Conference to Adopt a Global Programme of Action for the Protection of the Marine Environment from Land-based Activities (Washington, D.C., October 23–November 3, 1995), IFCS was invited to develop recommendations and information on international action, including any information that would be needed for a possible decision on an appropriate international legal mechanism on POPs, to be considered at the respective 1997 sessions of the UNEP GC and the World Health Assembly (WHA), the policy body of the World Health Organisation. At a UNEP meeting in Washington (Oct. 23–Nov. 3, 1995), countries adopted a Global Programme of Action for the Protection of the Marine Environment which, in part, recognized the importance of controlling releases of POPs, specified actions that should be taken on POPs, and encouraged countries to participate actively in implementing GC 18/32. The following paragraph from the Washington Declaration on Protection of the Marine Environment from Landbased Activities (November 2, 1995) was, therefore, taken into consideration in implementing Decision 18/32. “17. Acting to develop, in accordance with the provisions of the Global Programme of Action, a global, legally binding instrument for the reduction and/or elimination of emissions, discharges and, where appropriate, the elimination of the manufacture and use of the persistent organic pollutants identified in decision 18/32 of the Governing Council of the United Nations Environment Programme. The nature of the obligations undertaken must be developed recognizing the special circumstances of countries in need of assistance. Particular attention should be devoted to the potential need for the continued use of certain persistent organic pollutants to safeguard human health, sustain food production and to alleviate poverty in the absence of alternatives and the difficulty of acquiring substitutes and transferring of technology for the development and/or production of those substitutes.”
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2.2 Implementing the Mandate
An international multi-stakeholder working group (Working Group) was established to implement Decision 18/32. Initially established as a Working Group under UNEP, the group was later adopted by IFCS in order to discharge IFCS obligations to provide recommendations to UNEP Governing Council as requested in Decision 18/32. This Working Group included representatives from intergovernmental organizations, governments, industry, public interest groups and scientific organizations from around the world. In initiating the assessment process requested by Decision 18/32, the Working Group took into account related international initiatives including: (a) UNEP GC Decision 18/12, which concerns the development of a legally binding instrument for the application of the Prior Informed Consent (PIC) procedure for certain hazardous chemicals in international trade, recognizing that some of the POPs specified in Decision 18/32 were covered by current voluntary PIC procedures; (b) UNEP GC Decision 18/31, which encouraged support for the Global Programme of Action for the Protection of the Marine Environment from Landbased Activities (wherein specific reference was made to POPs) that was subsequently accepted at the UNEP Intergovernmental Conference, as reflected in the Washington Declaration on Protection of the Marine Environment from Land-based Activities, and that involves countries in national, regional and international activities to implement the Plan; (c) the negotiations initiated in 1996 on a POPs protocol under the UN ECE Convention on LRTAP (concluded in 1998 and now referred to as the Aarhus POPs Protocol); and (d) the regional seas agreements, including conventions and protocols. The Working Group first met in Washington, D.C. (October 1995) and agreed to the development of a basic review of chemistry and toxicology of the 12 POPs. The result was a report prepared for the International Programme on Chemical Safety entitled Persistent Organic Pollutants, An Assessment Report on DDT, Aldrin, Dieldrin, Endrin, Chlordane, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, Polychlorinated biphenyls, Dioxins and Furans (December 1995). This report was considered at a meeting of the Working Group in Canberra,Australia (March 1996) and provided the basis for the Working Group to conclude that sufficient information was available on the chemistry, toxicology, transport pathways, origin, transport and deposition of the 12 specified POPs to demonstrate the need for immediate international action and to provide a basis for moving forward on realistic response strategies. The significance of achieving agreement on this conclusion cannot be understated as it marked a turning point in the consultations from a discussion of whether action was warranted to a discussion of what action to take and how to proceed. The Working Group met for the third and final time in Manila, Philippines (June 1996) and developed the Final Report of the Intergovernmental Forum on Chemical Safety ad hoc Working Group on Persistent Organic Pollutants (IFCS re-
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port) which included recommendations for future action on POPs. The IFCS report and recommendations were unanimously supported by all stakeholders and submitted to UNEP and WHA for consideration at their respective 1997 meetings. Several documents were developed in addition to the final IFCS report and most of these are available on the UNEP POPS website. 2.3 Conclusions and Recommendations
The IFCS conclusions and recommendations were approved by both UNEP Governing Council (Decision 19/13C, February 3, 1997) and the WHA (Resolution WHA50.13, May 12, 1997). The key IFCS conclusion was that sufficient scientific information was available on the 12 specified POPs to demonstrate the need for immediate international action and to provide a basis for moving forward on realistic response strategies. Based on acceptance of this key conclusion, UNEP and WHA also accepted the IFCS recommendation that immediate international action should be initiated to protect human health and the environment through measures which will “reduce and/or eliminate ... the emissions and discharges of the 12 POPs” and “where appropriate, eliminate production and subsequently the remaining use of those POPs that are intentionally produced”. UNEP GC agreed to begin negotiation of a global legally binding instrument “by early 1998” and to conclude this task “preferably by the year 2000”. It was noted that proposed action programs should take into account that the 12 specified POPs include pesticides, industrial chemicals, and unintentionally produced by-products and contaminants, and that, within the framework of overarching objectives that were to be negotiated by an intergovernmental negotiating committee (INC), different approaches were needed for each category of POPs. The negotiation mandate was now in hand, and it was time-bound. 2.4 Actions in Support of the Negotiation Process
UNEP Governing Council urged governments to initiate action on the recommendations in the IFCS report and to provide technical assistance, capacity building and funding to enable developing countries and countries with economies in transition to take appropriate action on POPs. Governing Council Decision 19/13C also requested UNEP to initiate immediate action on POPs in response to recommendations in the IFCS report including: (a) general awareness raising on the national, regional and global aspects of POPs; (b) information exchange, within and between countries and intergovernmental organizations; (c) promoting information exchange on alternative products and processes to reduce or eliminate POPs generation, use and release;
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(d) assisting countries in identifying and developing inventories of PCBs and in identifying world-wide capacity to destroy PCBs; (e) developing inventories of information on dioxins and furans, including sources of releases and practices to manage these releases; and (f) collecting information that will be used in the INC negotiations to assist the development of criteria and a process for identifying additional POPs. At the second meeting of the IFCS (Ottawa, Canada, February 10–14, 1997), countries were informed of the progress of the ad hoc Working Group on POPs and agreed to continue the Working Group to assist in preparing for the UNEP negotiation process and to focus efforts of governments to take action on POPs. As a result, joint UNEP/IFCS regional and sub-regional workshops were held at the following locations to raise awareness of the many issues that had to be addressed in preparing nations for the commencement of the UNEP negotiation process in early 1998 and in identifying and taking action on POPs problems at the local, regional and international levels. – – – – – – – –
St. Petersburg, Russia (July 1–4, 1997); Bangkok, Thailand (November 25–28, 1997); Bamaco, Mali (December 15–18, 1997); Cartegena, Columbia (January 27–30, 1998); Lusaka, Zambia (March 17–20, 1998); Iguassu Falls, Argentina (April 1–3, 1998); Kranska Gora, Slovenia (May 11–14, 1998); and Abu Dhabi, United Arab Emirates (June 7–9, 1998).
The workshops attracted representatives of governments, industry, academia, labor and public interest groups from 138 countries and provided an opportunity to gather the views and concerns of countries in the regions with regard to the scientific, technical, social and economic challenges that needed to be addressed during the development and implementation of a global legally binding treaty to reduce the releases of POPs to the environment. Several other workshops were held during the conduct of the negotiations including the following: – Regional Workshop on Management of Persistent Organic Pollutants (Hanoi, Vietnam, March 16–19, 1999). – Workshop on the Management of Persistent Organic Pollutants (POPs) for the South African Development Community (SADC) region (Lusaka, Zambia, February 14–16, 2000). – Workshop on sustainable approaches for pest and vector management and opportunities for collaboration in replacing POPs pesticides (Bangkok, Thailand, March 6–10, 2000). Reports that include the papers presented at all eleven workshops are available on the UNEP POPs web site (http://chem.unep.ch/pops/) and in hard copy format from UNEP Chemicals in Geneva (Tel.: +41-22-917-1234; Fax: +41-22-797-3460; e-mail:
[email protected]).
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2.5 The Negotiations
In June 1998, UNEP convened an INC with a mandate to prepare, preferably by the year 2000, an international legally binding instrument for implementing international action, initially beginning with the 12 specified POPs, and taking into account the mandate in UNEP GC Decision 19/13C and the conclusions and recommendations of the IFCS report. Provision was to be made for commitments at a national and regional level allowing for a higher level of protection than that afforded through the global instrument. In addition, consideration should be given to voluntary measures that may be implemented as a complement to, or independently of, a legally binding instrument. Participation in the INC was open to governments and relevant non-governmental and intergovernmental organizations. Coordination among different regional and international initiatives on POPs was recognized as essential to ensure harmonized environmental and health outcomes from mutually supportive and effective programs that result in the development of policies with complementary and non-conflicting objectives. The negotiations were well attended, with participation by numerous intergovernmental organizations, a wide range of non-governmental organizations and over 120 countries. There was a series of five negotiation meetings: – – – – –
Montreal, Canada (June 29–July 3, 1998), Nairobi, Kenya (January 25–29, 1999), Geneva, Switzerland (September 6–11, 1999), Bonn, Germany (March 20–25, 2000), and Johannesburg, South Africa (December 4–10, 2000).
One of the requirements of the negotiation process was the development of science-based criteria and a procedure for identifying chemicals, in addition to the 12 specified POPs, as candidates for future international action. The process of developing the screening procedure involved reviews of criteria pertaining to persistence, bioaccumulation, toxicity and exposure in different regions, and took into account dispersion mechanisms for the atmosphere and the hydrosphere, migratory species and the need to reflect possible influences of marine transport and tropical climates. An expert body, the Criteria Expert Group (CEG), was established at the first meeting of the INC to carry out this work. The CEG, which met in Bangkok, Thailand (October 26–30, 1998) and Vienna,Austria (June 14–18, 1999), included scientific and socio-economic expertise relevant to the POPs issue and was representative of countries in different stages of development and from different geographical regions, as well as participants from relevant non-governmental and intergovernmental organizations. The CEG considered the criteria and procedure being considered by the UN ECE in the development of the Aarhus Protocol on POPs and also took full account of varied ecosystems and the circumstances of developing countries and countries with economies in transition, as well as the need to conserve biodiversity and protect endangered species. The principles set out in the Rio Declaration on Environment and Development, es-
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pecially Principle 15 that includes a reference to the precautionary approach, and the provisions of Chapter 19 of Agenda 21 were also taken into account. The result of this work was the inclusion in the Convention of a special provision (summarized below) concerning the evaluation and selection of chemicals that are candidates for addition to the Convention. One other issue arose during the negotiations that required special attention: the financial mechanism that would be established under the Convention to provide resources to developing countries and countries with economies in transition. This required a special meeting attended by representatives of eighteen countries in Vevey, Switzerland (June 19–21, 2000) to address the essential and desirable attributes of the financial mechanism. The results of this meeting proved to be of key importance in the final negotiation session in arriving at a consensus on this issue. All documents and reports relating to the negotiations are available on the UNEP POPs home page.
3 The Stockholm Convention on POPs The Stockholm Convention on POPs will enter into force when fifty countries will have ratified it. Once entry into force takes place, the countries that have ratified will meet as a Conference of the Parties (COP) to the Convention and will begin to take decisions on the operation of the Convention. The main provisions of the Stockholm Convention, other than those that relate simply to decision taking and administration of the Convention, are presented under the following headings: – – – –
General provisions; Control provisions; Procedure for adding new POPs; Financial and technical assistance.
3.1 General Provisions
The Preamble of the Convention acknowledges that due to their physical, chemical and toxicological properties, the release of POPs to the environment causes local and long-range impacts on ecosystems and human health, particularly on women and Arctic indigenous groups. It also recognizes that all sectors of society have a role to play in taking action to reduce and/or eliminate the releases and discharges of POPs to the environment, and recognizes the need to develop and implement environmentally sound products and processes as alternatives to the generation, use and/or release of POPs. The concept of “precaution” is introduced in the Preamble, reflected in a number of operative provisions, and is referenced prominently in the Objective of the convention which states: “Mindful of the precautionary approach as set forth in Principle 15 of the Rio Declaration on Environment and Development, the objective of this Convention
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is to protect human health and the environment from persistent organic pollutants.” Under the Convention, each Party has the following general obligations: (a) develop an implementation plan within two years of the Convention coming into force and endeavor to implement the plan, which must be reviewed and updated on a periodic basis: stakeholders should be involved in all these actions; (b) designate a National Focal Point to interact with other Parties and the UNEP secretariat to facilitate the exchange of a broad range of information on the production, use and release of POPs and on alternatives to POPs; (c) promote and facilitate the following as they relate to public information, awareness and education on POPs and their alternatives: – awareness among policy and decision makers, – provision of available and up-to-date information to the public, – development and implementation of educational, training and public awareness programs, – public participation in developing and implementing measures to address POPs, and – training and development programs for all stakeholders; (d) encourage and/or undertake research, development, monitoring and cooperation on all aspects of POPs and their alternatives, including aspects relating to their environmental releases, trends in levels in the environment and humans, transport, fate, transformation, effects, socio-economic impacts, and release reduction and/or elimination; and (e) report to the COP on measures that the Party has taken to implement the Convention and on the effectiveness of the measures. In the future, the COP must evaluate the effectiveness of the Convention in reducing and/or eliminating the releases of POPs. This will be done by establishing a mechanism to acquire comparable monitoring data on the presence, levels and trends of POPs in environmental and biological media, as well as on regional and global environmental transport of POPs. This mechanism will tap into existing national, regional and global networks and sources of information, and its design will be addressed at the first meeting of the COP. The Convention specifies that the COP will review the first effectiveness report four years after the Convention has come into force. 3.2 Control Provisions 3.2.1 Intentionally Produced POPs
For all intentionally produced POPs (i.e., industrial chemicals and pesticides), the goal of the Convention is elimination of production and use. To achieve this goal, the production and use of an intentionally produced POP will be either eliminated or restricted and, in each case, trade will be restricted.
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3.2.1.1 The Initial 10 POPs
For nine of the initial ten intentionally produced substances that are included in the Convention, each Party will be required to “prohibit and/or take the legal and administrative measures to eliminate” the production and use of the POPs that are listed in Annex A (“Elimination”) of the Convention [i.e., aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex, polychlorinated biphenyls (PCBs) and toxaphene]. With regard to DDT, each Party will be required to restrict production and use to the “Acceptable Purposes” specified in Annex B (“Restriction”). With the exceptions of endrin and toxaphene, some “specific exemptions” with regard to production and/or use of the intentionally produced POPs have been included in Annex A and Annex B for each chemical. Any state on becoming a Party may register for one or more “specific exemptions” listed in Annexes A and B by informing the UNEP secretariat who will maintain a publicly available register as required by the Convention. Unless a Party specifies an earlier date, a specific exemption will be valid for a period of five years after the Convention comes into effect for a particular chemical. A Party may withdraw its exemption at any time, or may request an extension of five years to its exemption. Each request for an extension will be reviewed by the COP based on information submitted by the requesting Party justifying its continued need for the registered exemption. Parties that engage in activities involving intentional production or use of POPs under the “specific exemptions” or “acceptable purposes” provisions must take measures to prevent or minimize human exposure and releases to the environment. There are two high-profile POPs among the initial ten that warrant some detailed explanation: PCBs and DDT. With regard to PCBs, all Parties have agreed to cease production of PCBs and to eliminate the use of in-place equipment containing PCBs (transformers, capacitors, etc.) by 2025. The use of in-place equipment containing PCBs is a “specific exemption” under Annex A for all Parties that is subject to some conditions (e.g., use only in intact and non-leaking equipment) and restrictions (e.g., use is not permitted in food and feed processing areas).As all Parties are entitled to this exemption, Parties using the exemption will not be named in the Register as is the case for other intentionally produced POPs. Parties will make determined efforts to identify, label and remove from use equipment containing more than 0.005% (50 ppm) of PCBs, with higher priority given to equipment containing higher levels of PCBs. There is to be no trade in PCB equipment except for the purpose of environmentally sound waste management and, except for maintenance and servicing operations, there is to be no recovery for reuse in other equipment of liquids with more than 0.005% PCBs.Another goal is to achieve the environmentally sound management of PCB wastes as soon as possible but no later than 2028. Parties will report to the COP every five years on their progress in eliminating in-use equipment and the environmentally sound management of wastes, and the COP will review progress toward the 2025 and 2028 targets at fiveyear intervals, taking into account the Parties’ reports.
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A special regime has been agreed upon for DDT. The production and use of DDT will be eliminated except for Parties that notify the Secretariat of their intention to produce or use DDT in disease vector control programs, a specified “acceptable purpose” in Annex B. The production and/or use must be in accordance with WHO recommendations and guidelines on the use of DDT, and when locally safe, effective and affordable alternatives are not available to the Party. Such Parties will be included in a special publicly available DDT register maintained by the secretariat. Every three years, registered Parties will report on the quantities used, the conditions of use and the relevance to the Party’s disease management strategy. Each registered Party should develop national action plans to confine the use of DDT to disease vector management, explore alternatives to DDT, and take measures to strengthen health care and reduce the incidence of disease. All Parties will promote research and development to seek alternatives to DDT. The use of DDT will be allowed until such time as technically and economically feasible alternative products, practices or processes are available to countries that are currently reliant on DDT. The COP will review the situation at its first meeting and every three years thereafter to ascertain whether there is a continued need for DDT for disease vector control. There are two specific exemptions allowed for DDT related to its use as an intermediate in manufacturing other chemicals. 3.2.1.2 Provisions Applicable to All Intentionally Produced POPs
For all POPs in Annex A and Annex B, trade will be restricted. In general, imports and exports are limited to shipments intended either for environmentally sound disposal or to Parties with “specific exemptions” under Annex A or Annex B or with “acceptable purposes” under Annex B. Exports to Non-Parties may take place but there are conditions on both the Non-Party and the Party and accountability requirements for the use and disposal of POPs. The control provisions applicable to intentionally produced POPs listed in Annex A or B do not apply to those quantities of a chemical: (a) used for laboratory-scale research or as a reference standard; (b) occurring as unintentional trace contaminants in products and articles; or (c) occurring as constituents of articles manufactured or already in use before or on the date of entry into force of a relevant obligation concerning that chemical provided that a Party has notified the secretariat that a particular type of product remains within use within that Party, whereupon the secretariat will make the notification publicly available. One final exemption should be noted that is limited to two substances of the initial 10 (HCB and DDT) but that could be applicable to POPs that are added to the convention in the future. Provision has been made for a Party to produce or use these substances as closed-system site-limited intermediates that are chemically transformed in the manufacture of other chemicals that do not exhibit the properties of POPs. This requires notification to the secretariat of information on the
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total amounts produced or used, the nature of the site-limited process, and the amount of the HCB or DDT present in the final product. The notifications will be made publicly available. Such production or use is not considered a “specific exemption” and will cease after a period of ten years unless a Party submits a new notification to the secretariat, in which case the period will be extended for another ten years unless the COP decides otherwise. Those Parties with regulatory and assessment schemes for new industrial chemicals or pesticides shall take “measures to regulate with the aim of preventing the production and use of ” new POPs. This measure is one of the precautionary measures included in the convention and is intended to prevent the commercial introduction of new substances that may have POPs properties. In addition, countries with regulatory and assessment schemes for industrial chemicals or pesticides shall, in conducting assessments of in-use substances, consider the screening criteria (in Annex D) for candidates for addition to the Convention. This will allow the identification of possible POPs as soon as possible in these assessment programs. 3.2.2 POPs that are not Intentionally Produced
POPs that are not intentionally produced are listed in Annex C of the convention (i.e., dioxins, furans, HCB, PCBs). For these chemicals, the intent is to reduce their total releases derived from anthropogenic sources, with the goal of “their continuing minimization and, where feasible, ultimate elimination”. In pursuit of this goal Parties are to: (a) develop action plans within 2 years of entry into force of the Convention for them, and implement their plans to identify, characterize and address the release of the chemicals in Annex C. The action plan shall include the following elements: – evaluate current and projected releases, including the development and maintenance of source inventories and release estimates, – evaluate efficacy of the Party’s laws and policies to manage such releases, – develop strategies to reduce releases, – promote education and training on the strategies, – review success of strategies every five years and report to the COP, and – develop a schedule for implementation of the action plan; (b) promote the application of available, feasible and practical measures to achieve realistic and meaningful levels of release reduction or source elimination; (c) promote the development and, where appropriate, require the use of substitute or modified materials, products and processes to prevent the formation and release of the POPs in Annex C; (d) promote, and as provided for in an action plan, require the use of best available techniques (BAT) for new sources within the following industrial source categories (as specified in Part II of Annex C) that have a potential for comparatively high formation and release of POPs to the environment: – waste incinerators (municipal, hazardous or medical waste; or sewage sludge),
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– cement kilns firing hazardous wastes, – pulp production involving chlorine, and – thermal processes used in the metallurgical industry (secondary production of aluminum, copper or zinc; sinter plants in the iron and steel industry) and phase in any BAT requirements for such sources as soon as practicable but no later than four years after the entry into force of the Convention for a Party. For these identified new source categories, Parties shall promote the use of best environmental practices (BEP). Guidance on both BAT and BEP will be developed by the COP; and (e) promote, as provided for in an action plan, the use of BAT and BEP for new sources within the following categories (as specified in Part III of Annex C) and for existing sources within all categories in Parts II and III of Annex C: – open burning of wastes (including landfill sites), – thermal processes in the metallurgical industry not specified in Part II, – residential combustion sources, – fossil-fuel fired utility and industrial boilers, – firing installations for wood and other biomass fuels, – chemical production processes releasing unintentionally produced POPs (e.g., production of chlorophenols and chloranil), – crematoria, – motor vehicles, especially those burning leaded gasoline, – destruction of animal carcasses, – textile and leather dying and finishing, – shredder plants for the treatment of end-of life vehicles, – smouldering of copper cables, and – waste oil refineries. Annex C of the Convention also contains guidance on BAT and BEP and on general measures to prevent the formation and release of unintentionally produced POPs. 3.2.3 POPs in Stockpiles or Wastes
For POPs that are in stockpiles or wastes, the goal is to ensure the environmentally sound management of stockpiles, wastes, and products and articles upon becoming wastes that consist of, contain or are contaminated by POPs. To this end Parties shall: (a) develop and implement strategies to identify the stockpiles, products and articles in use, and wastes containing POPs; (b) manage stockpiles in a safe, efficient and environmentally sound manner until they are deemed to be wastes; (c) take measures to handle, collect, transport and store wastes in an environmentally sound manner and dispose of these wastes in a way that destroys the POP content, or otherwise in an environmentally sound manner taking into account international rules, standards and guidelines;
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(d) not allow recovery, recycle, reclamation, direct reuse or alternative uses of POPs; (e) not transport these materials across international boundaries without taking into account international rules (e.g., Basel Convention); and (f) develop strategies for identifying contaminated sites and, if remediation is attempted, do it in an environmentally sound manner. 3.3 Procedure for Adding New POPs
The Convention will be able to respond as new scientific and other information becomes available on other chemicals as provision has been made for the addition of new POPs through application of scientific criteria and an agreed process for evaluation of candidates that will be proposed by Parties in the future.A POPs Review Committee will be set up to advise the COP on the merits of proposals submitted by Parties that must address the following criteria contained in Annex D: – chemical identity (names, CAS number, IUPAC name, structure, etc.); – persistence: – evidence that the half life of the chemical in: – water is greater than 2 months, or – soil is greater than 6 months, or – sediment is greater than 6 months, or – evidence that the chemical is sufficiently persistent to warrant consideration under the Convention; – bio-accumulation: – evidence that the bioconcentration factor or the bioaccumulation factor in aquatic species for the chemical is greater than 5000, or absent such data, that the log KO/W is greater than 5, or – evidence that a chemical presents other reasons for concern (e.g., high bioaccumulation in other species, high toxicity or ecotoxicity), or – monitoring data in biota indicating that the bioaccumulation potential of a chemical is sufficient to warrant consideration under the Convention; – potential for long range transport: – measured levels of the chemical in locations distant from the sources of release that are of potential concern, or – monitoring data showing that long-range environmental transport of the chemical may have occurred, or – environmental fate properties and/or model results that show that the chemical has a potential for long-range environmental transport: for a chemical that migrates significantly through the air, its half life in air should be greater than 2 days; – adverse effects: – evidence of adverse effects to human health or the environment that justifies consideration under the Convention, or – toxicity or ecotoxicity data indicating the potential for damage to human health or the environment.
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In submitting a proposal, a Party must address these criteria and include a statement of the reasons for concern and the need for global control. The secretariat will review the proposals and submit complete ones to the POPs Review Committee for examination. If the Committee is not satisfied that the screening criteria have been fulfilled, the proposal is set aside, although there are provisions for a Party to resubmit a proposal. If the committee is satisfied that the screening criteria have been fulfilled, then the proposal and the committee’s report are made publicly available and all Parties and observers are invited to submit the following information specified in Annex E for development of a risk profile that further elaborates on and evaluates the information in Annex D and that submitted on Annex E: – sources (production data, uses, releases, etc.), – hazard assessment for the endpoint(s) of concern, – environmental fate (chemical and physical properties, persistence, environmental transport, degradation and transformation, etc.), – bioconcentration or bioaccumulation factor, – monitoring data, – exposure and bioavailability data, – national and international risk evaluations, assessments or profiles, – hazard classification and labeling information, and – status of the chemical under international conventions. If, on the basis of the risk profile, the Committee is not satisfied that the proposal should proceed, it will be set aside, although there are provisions for a Party to request reconsideration and ask for more information to be submitted within a period of one year. If the committee is satisfied that the proposal should proceed, then the proposal and the committee’s report are made publicly available and all Parties and observers are invited to submit the following information specified in Annex F for development of a risk management evaluation that includes an evaluation of possible control measures for the chemical, encompassing the full range of options, including management and elimination. Relevant information should be provided relating to socio-economic considerations associated with possible control measures to enable a decision to be taken by the COP: – efficacy and efficiency of possible control measures in meeting risk reduction goals (technical feasibility; and costs – including environmental and health costs); – alternative products and processes (technical feasibility; costs – including environmental and health costs; efficacy; risk; availability; and accessibility); – positive and/or negative impacts on society of implementing possible control measures [health – including public, environmental and occupational health; agriculture, including aquaculture and forestry; biota (biodiversity); economic aspects; movement towards sustainable development; and social costs]; – waste and disposal implications, in particular, obsolete stocks of pesticides and clean-up of contaminated sites (technical feasibility; and cost); – access to information and public education;
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– status of control and monitoring capacity; and – any national or regional control actions taken, including information on alternatives, and other relevant risk management information. The Committee shall, based on the risk profile and the risk management evaluation, recommend whether the chemical should be considered by the COP for listing in Annexes A, B and/or C. The COP, taking due account of the Committee’s recommendations and any scientific uncertainty, shall decide, in a precautionary manner, whether to list the chemical and specify its related control measures in Annexes A, B and/or C. This process of evaluating nominations incorporates precaution in a number of ways to ensure that all possible candidates are thoroughly evaluated on the basis of available scientific data to see if they possess the properties that would indicate POPs behavior.As mentioned above, there are safeguards in the process to ensure that all Parties have the opportunity to get a full hearing on any nominated candidate. 3.4 Financial and Technical Assistance
One of the key features of the Convention is the recognition that developing countries and countries with economies in transition will need technical and financial assistance in order to meet their obligations as Parties to the Convention. Regional and subregional centres will be established for capacity building and transfer of technology to assist countries in need. The developed countries have undertaken to provide technical assistance and new and additional financial resources to meet the agreed full incremental implementation costs, and the Global Environment Facility has been named as an interim financial mechanism to handle the funding of capacity building and other related activities. It is expected that projects will begin immediately after the Stockholm conference in May 2001 to enable developing countries to prepare to meet their future convention requirements.
4 Future Actions on POPs The POPs Convention was adopted at a diplomatic conference that was held from May 22–23, 2001, in Stockholm. Since then 150 countries and the European Union have signed and 10 countries have ratified the convention. When 50 countries have ratified the convention, it will come into force. While this process will take a few years, that does not mean that action on POPs will not take place for years to come: far from it! At the Stockholm conference, countries agreed to continue with meetings of the Intergovernmental Negotiating Committee that developed the Convention to coordinate and promote activities on POPs reduction and elimination and lay the groundwork for the eventual first meeting of the COP. The process of negotiation stimulated widespread interest and concern about the effects of POPs and many
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actions have taken place or are underway. UNEP has developed a master list of actions that reports that over 108 countries have already taken or are taking some sort of action on POPs. Intergovernmental organizations and non-governmental organizations have similarly responded by taking actions to reduce and/or eliminate POPs generation and release. For example, during the negotiation process, environmental non-governmental organizations (ENGOs) established an International POPs Elimination Network (IPEN) that has now grown to include over 300 ENGO’s, and they are promoting action on POPs around the world. Thus, there is already underway a large effort by all sectors of society to deal with the POPs issue and to prevent the introduction of new POPs into commerce. Those interested in obtaining additional information on POPs activities should consult the UNEP POPs home page or the UNEP Chemicals POPs Team (11–13 chemin des Anemones, 1219 Chatelaine/Geneva, Switzerland, Tel.: +41-22-917-1234; Fax: +41-22-797-3460; e-mail:
[email protected]).
CHAPTER 3
Criteria for Additional POPs Bo A. Wahlström UNEP Chemicals, 11-13, Chemin des Anémones, 1219 Châtelaine, Genève, Switzerland E-mail:
[email protected] The Intergovernmental Negotiating Committee for a global treaty on POPs developed sciencebased screening criteria for identifying additional substances as candidates for future international action. The screening criteria relate to properties, e.g., persistence, bio-accumulation, potential for long-range environmental transport and adverse effects. Numerical cut-off values have been agreed for persistence in different media and for bio-accumulation but not for longrange environmental transport potential and adverse effects. The cut-off values may be modified by certain external factors, e.g., very high toxicity. Data for individual nominated substances or groups of substances will be compared to the screening criteria as a first step in the assessment. At later steps an in-depth assessment will be undertaken. Keywords: Criteria, POPs, Persistence, Bio-accumulation, Long-range transport, Pollutants
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Background
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Annex D of the Stockholm Convention on POPs . . . . . . . . . . . . . . 42 Information Requirements and Screening Criteria . . . . . . . . . . . . . 42 Annex E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Information Requirements for the Risk Profile . . . . . . . . . . . . . . . 43 Annex F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Information on Socio-Economic Considerations . . . . . . . . . . . . . . 44 7
References
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1 Background In May 1995 the 18th meeting of the UNEP Governing Council (GC) adopted decision GC18/32 [1] inviting the Inter-Organization Programme for the Sound Management of Chemicals (IOMC), working with the International Programme on Chemical Safety (IPCS) and the Intergovernmental Forum on Chemicals Safety (IFCS) to initiate an expeditious assessment process on persistent organic pollutants, starting with an initial list of twelve substances. It further invited the IFCS to develop, based on the result of the assessment process and the outcome of the Washington Conference to Adopt a Global Programme of Action for the Protection of the Marine Environment from Land-based Activities,“recommendations and information on international action, including such information as would be needed for a possible decision regarding an appropriate international legal mechanism.” In response to this decision the IFCS established an ad hoc Working Group on Persistent Organic Pollutants (POPs), which met in Manila in June 1996. In the report of the meeting [2], the Working Group recommended that immediate international action should be initiated to protect human health and the environment through measures which would reduce and/or eliminate emissions and discharges of the 12 POPs specified in UNEP GC Decision 18/32. The Working Group also highlighted “the need to develop science-based criteria and a procedure for identifying additional POPs as candidates for future international action” and recommended “that the proposed INC should be directed to establish, at its first meeting, an expert group to carry out this work”. Based on the recommendations of the IFCS ad hoc Working Group the UNEP GC at its 19th meeting in its Decision 19/13C invited the Executive Director of UNEP to convene an intergovernmental negotiating committee to prepare an international legally binding instrument on POPs [3]. The GC also requested the INC to establish an expert group to develop criteria and a procedure for identifying additional POPs. The Criteria Expert Group (CEG) for POPs was established at the first session of the INC in Montreal in June 1998. The CEG met twice, in October 1998 in Bangkok [4] and in June 1999 in Vienna [5], and developed proposals for crite-
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ria and a procedure for identifying additional POP that were submitted to the third session of the INC in Geneva in September 1999.
2 Recent Regional and International Initiatives The Working Group on Strategies (WGS) under the 1979 Geneva Convention on Long-Range Transboundary Air Pollution (LRTAP) under the auspices of the UN Economic Commission for Europe (UNECE) started work in the early 1990s to prepare a protocol on persistent organic pollutants under the regional convention. Several working papers were developed in which criteria on persistence, bioaccumulation and toxicity were elaborated and tested on a set of chemicals. As a result the Executive Body (EB) of the LRTAP Convention adopted Decision 1998/2 on criteria to be used to identify additional substances [6]. The EB Decision listed numerical criteria for persistence in air, water, soil and sediments as well as for volatility and bio-accumulation. It also described data elements to be gathered for a more comprehensive assessment to develop a risk profile. The POPs Protocol was adopted in June 1998 in Aarhus, Denmark [7]. Some other initiatives to develop criteria for persistent organic pollutants should be mentioned: – In July 1998 the Society for Environmental Toxicology and Chemistry (SETAC) hosted a workshop in Fairmont Springs, Alberta, Canada, to develop a strategy for the selection and assessment of persistent toxic substances. The process developed did not contain any numerical figures but outlined a stepwise open and transparent procedure that would maximise the use of scientific data and allow for input from interested parties at all stages of the process [8]. – The Commission on Environmental Co-operation (CEC) established under the North American Agreement on Environmental Co-operation (NAAEC) similarly has developed criteria for identifying candidate substances for regional action including persistent toxic bio-accumulators [9]. – Canada in 1994 developed a Toxic Substances Management Policy (TSMP) which listed criteria, e.g., persistence and bio-accumulation for organic substances designated for virtual elimination [10]. – A Swedish Government Committee on Chemicals Policy has recently (Spring 2000) proposed criteria for identifying persistent and bio-accumulating substances with a view towards their elimination [11].
3 General Characteristics of the Criteria and their Application Existing systems for selecting and evaluating POPs generally consider properties such as persistence, bio-accumulation and potential for long-range transport at an early stage in the selection process. These properties are considered separately in a step-wise process, which in some cases starts with properties that facilitate transport, e.g., volatility and persistence in air (UNECE) while others start with screening data on persistence in all media (POPs INC). In addition, data on bioaccumulation and evidence of long-range transport is assessed together with ev-
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idence of adverse effects on health and environment in the screening assessment step. At a later stage more comprehensive data on effects, uses etc. are used together with available exposure data to assess potential risks.
4 The POPs Criteria Process 4.1 Overriding Principles for the Criteria Work
In a paper presented to the 1st POPs Intergovernmental Negotiating Committee the author outlined some desired general characteristics of the criteria to be developed [12]. First of all, criteria should be based on sound science. Such criteria should be able to stand the test of time and not be influenced by changing social and political conditions. The stress on the need to establish science-based criteria also reflects the awareness that science in related fields is advancing with regard to our understanding the factors that determine the behaviour of chemicals in the environment and in organisms, including human beings. A better understanding will also in the long run lead to potentially better prediction of the behaviour of suspected chemicals that lack a comprehensive data base. Secondly, criteria should be open and transparent. In the present context this means that they should be understandable to the educated lay public and to policy makers. The procedure whereby a chemical is nominated, evaluated and accepted or rejected as a candidate POP should be easily understood. The process should also include steps for parties, to contribute new, relevant data to modify, clarify, reject or confirm decisions to move a chemical along its path towards its final designation by a Conference of Parties to the Stockholm Convention on Persistent Organic Pollutants (POP) as a Persistent Organic Pollutant of global concern. 4.2 Characteristics of POPs
Chemicals that are POPs are multi-compartment substances that typically move between the environmental compartments of air, water, soil, sediment and biota. In each compartment spread by diffusion needs to be considered, as well as bulk movement with moving media, e.g., air currents, ocean currents, rivers or aquifers. POPs may also move with biota. Migratory butterflies, birds or cetaceans might each constitute a quantitatively small route of dispersal of POPs, but could be important routes of exposure for other organisms. In the process to select candidate POPs all routes of environmental dispersal should be considered. Most potential POPs under discussion contain aromatic or alicyclic rings. Many, but not all, contain carbon-halogen bonds that, to a varying degree, resist degradation by physical, chemical or biological means. They may be characterized as semi-solids with low, but distinct, vapour pressures and the lipid solubility is usually several orders of magnitude higher than the water solubility.A typical POP would be released to air, directly from emissions, or indirectly through
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evaporation from water, soil or vegetation. Once in air it would travel a significant distance with existing winds, generally southwestern on the Northern Hemisphere and northwestern on the Southern Hemisphere. At higher latitudes, or higher altitudes, the substance would condense out of the air due to lower air temperature.When deposited on water, soil or vegetation, it would remain in that medium for a long time. It would redistribute itself between lipid and aqueous phases in media and biota with the net result being a high concentration in lipids and a low one in water. In water, soil and sediment, lipids are mainly found in biota. In cold regions thick fatty layers in warm-blooded animals protect against heat loss and also provide an important energy source. They also become significant storage sites for POPs. Predatory animals in cold regions, including man, need fat as an energy source because of its high specific energy content, thus enhancing the tendency of POPs to accumulate in the food chain. In warmer climates exposures may occur closer to the source, e.g., occupational exposure during use, or local exposure caused by run-off from use or leaking from stockpiles. Food, such as fish may be a major route of intake also in warmer climates and POPs may accumulate in the food chain and reach high levels in predatory species in these conditions. The scientific knowledge on the behaviour of POPs in the environment is increasing. Models for predicting the distribution of chemicals in environmental media are coming closer to agreement with environmental data. Consistent criteria for persistence based on scientific models may soon be developed for all environmental media and the environmental distribution and potential for long-range transport of chemicals, including POPs, scientifically evaluated by models. 4.3 Parameters to Consider
For the Stockholm Convention, the following parameters have generally been identified to be considered primarily for setting criteria to identify POPs: (a) Persistence: The ability of a substance to resist degradation in various media, such as air, soil, water and sediment, generally measured as the half-life of the substance in the medium, i.e., the time taken for the concentration of the substance to decrease by 50%; (b) Bio-accumulation: The ability of a substance to accumulate in living tissues to levels higher than those in the surrounding environment, expressed as the quotient between the concentration in the target tissue and the environmental concentration; (c) Toxicity: The ability of a substance to cause injury to humans or the environment; (d) Potential for long-range transport: The ability of a substance to travel long distances, hundreds and thousands of kilometers, from its point of origin. This property, that may be either evaluated by modeling or measured by sampling of biota in remote regions, is considered to be critical for identifying a chemical as a persistent organic pollutant of global concern;
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In addition it has been proposed that chemicals which are biodegradable but which may give rise to persistent exposure to the environment due to continuous releases or emissions should also be considered as persistent. The issue of bioavailability has also been raised. Some of the above criteria lend themselves to the assignment of numerical cut-off values, while others need to be qualitatively assessed. In the actual situation of applying the criteria to an individual substance other factors, e.g., climate need to be considered. 4.3.1 Persistence
Persistence reflects the ability of the substance to resist degradation by physical, chemical or biological means. Persistence may be expressed in various ways. In laboratory testing of new and existing chemicals for the assessment of hazard and risk, the Organisation for Economic Cooperation and Development (OECD) Test Guidelines are often used together with the (OECD) Principles for Good Laboratory Practice, as adopted under the OECD Council Act on Mutual Acceptance Data [13–15]. There are guidelines for testing the easy biodegradability of substances as well as for measuring their inherent biodegradability. These, however, are primarily focused on differentiating between chemicals that are easily biodegradable and those that are not. Persistent chemicals in the present sense constitute a subset of those that are not easily biodegradable, and may thus not be adequately identified using existing methods. Discussions are underway to refine and develop existing methods to make them better suited for application to the evaluation of POPs. Persistence depends not only on the substance tested but also on the test medium. Therefore, even seemingly simple degradation tests may give results that are open to interpretation. Any single figure for half-life in a medium, without the corresponding information on the test conditions should be treated with extreme caution. Data from non-standard tests should be handled the same way. Comparisons with substances for which extensive data exist (bench-marking) may facilitate the evaluation. 4.3.1.1 Persistence in Air
The normally used persistence criterion for air is the half-life in air, expressed in days [6]. Modeling shows that substantial quantities of substances with a half-life of two days or more still remain in air after 8–10 days. During that time the substance may be transported several thousand kilometers. Substances may be transported in air absorbed to particles, which increases their half-life. Air persistence data should be considered together with the presence of the substance in remote regions, as demonstrated by the monitoring of biota or other media.
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4.3.1.2 Persistence in Water, Soil and Sediments
The half-life of a substance in soil, water or sediments has been proposed as a possible criterion to identify POPs [6]. Chemicals with long persistence half-lives in water, soil or sediments have a high potential for accumulation in the medium and also for uptake by living organisms. The pattern of environmental release or application is of great importance. Substances that are applied once annually, for example some pesticides, may have half-lives of several months and still not accumulate in soil in spite of long-term use. Most industrial chemicals, however, are not used in this way. Releases and emissions usually occur continuously from many sources, including diffuse releases from products or articles containing the substance. In practice, there is no clear demarcation line between persistent and non-persistent chemicals.Also laboratory data have to be applied with caution to real-life situations. Physical, chemical and biological factors such as temperature, pH and amount and content of biological fraction may greatly influence persistence under field conditions, as well as processes such as photolysis and hydrolysis. Substances that normally degrade in the environment may behave as persistent under some conditions, e.g., atrazine in ground water and vice versa degrade more quickly in the environment than indicated by laboratory tests, e.g., pyrethroids in microcosms or field trials. 4.3.2 Bio-Accumulation
Bio-accumulation is a measure of the potential for a chemical to concentrate in living tissues.While persistent substances are diluted by dispersion during longrange transport, bio-accumulation counteracts this process. Bio-accumulation can best be measured in intact organisms in the laboratory or in the field. It is usually expressed as the bio-concentration factor (BCF) or bio-accumulation factor (BAF). Bio-accumulation measured in this way confirms that uptake takes place and integrates accumulation with biodegradation by the organism. Values between 1,000 and 5,000 for BCF in fish have been proposed as cut-off criteria for identifying bio-accumulating substances [6, 8, 11].Among factors that influence BCF are choice of species, study design, lipid content of the organism and others. Systematic testing of existing chemicals is ongoing in several national, regional and international programmes, but, to date, only a fraction of all commercially available chemicals has been studied for bio-accumulating properties. In the absence of data from animal testing, the octanol-water partition coefficient (Kow) has been used as a surrogate. It can be measured relatively easily and even calculated on the basis of the molecular formula and structure and for many substance groups it correlates well with BCF. It must be noted, however, that it should primarily be used as a screening tool, since by itself it will not tell whether a chemical is actually taken up by the organism, or, if taken up, whether it is actually accumulated. Chemicals with molecular weights higher than 1,000 may have a high Kow, but such large molecules are, in general, not bioavailable because they
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cannot pass biological membranes. There are also chemicals with high Kow values that are extensively metabolized into less persistent products. A high Kow (>10,000) should therefore always be confirmed by testing the BCF in an animal species. At present, methods are available for aquatic species only. 4.3.3 Long-Range Environmental Transport
The best way to establish whether or not long-range transport occurs is through direct measurement of POPs, e.g., in monitoring programmes in remote locations such as the Arctic or Antarctic, isolated islands, or mountain areas. Measurements in biota and human populations also provide data that may be used in risk assessments. Long-range transport may include regional transport within a continent, such as transport from a densely populated coastal area with intensive agriculture to inland mountainous regions. The potential for long-range transport may be assessed indirectly by persistence times in air, water or soil and by factors such as volatility. The behaviour of persistent chemicals in the environment is dependent, however, on a host of other factors, such as adsorption to particles, soil binding, etc., which makes prediction difficult. Long-range transport of POPs may also occur through migratory birds that accumulate substantial amounts of POPs because of local use in their tropical winter quarters. Some of these fall prey to predatory birds in their summer quarters, thus transferring their POPs content up the food chain but also from one part of the globe to another.Although rough calculations show this transport to be of minor quantitative importance in relation to air and water it might still be of importance as a route of exposure for specific predatory species. The marine transport through currents, or through repeated dissipation and condensation, as well as through migrating marine species is thought to an order of magnitude lower than the air transport. However, residence times for POPs in water are several orders of magnitude higher than in air, and the exchange mechanisms are slow enough to allow for continued releases from the oceans over several centuries or millennia. The recently evidenced presence of POPs in the deep sea at depths of 1000 meters and more are a cause of continued concern. The long-range environmental transport criterion is basically qualitative in character and needs to be assessed on a case-by-case basis for each POP substance. 4.3.4 Volatility
Volatility is sometimes considered as a separate criterion [6] and sometimes viewed as one important property together with other environmental fate properties (see below).Volatility is usually expressed as the vapour pressure of a substance.A volatility of less than 1,000 pascal has usually been assigned as a cut off value to distinguish between very volatile and semi-volatile substances. Chemicals that have a vapour pressure higher than 1,000 pascal are gases at normal tem-
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peratures, distribute exclusively to air and are not likely to be POPs. The volatility criterion should be applied together with persistence in air and/or data on presence in remote regions. Other ways to indicate a substance’s tendency to volatilize have been suggested, such as Henry’s law constants and fugacity calculations. It has been suggested that many factors, including volatility contribute to the fate of a substance in the environment. If the focus is on POPs in general and not specifically on long-range transboundary air transport, volatility becomes less critical as a property for criteria setting. 4.3.5 Toxicity
International schemes exist for identifying some acutely toxic chemicals, e.g., WHO [16]. However, for the long-term and chronic effects, some of which may appear at extremely low levels, there are at present no internationally agreed quantitative toxicity criteria for identifying POPs. Therefore, a qualitative approach needs to be applied taking into account a wide variety of toxicity and eco-toxicity endpoints. Chronic and irreversible effects should be assessed differently from acute and transient effects. Assessment of toxicity also requires an assessment of dose. Substances of high toxicity may cause concern even when they are present in the environment in very low concentrations, e.g., if they bioaccumulate to a significant degree. Adverse effect levels should, where possible, be compared to possible exposures. Toxicity is therefore essentially a qualitative parameter at the screening stage for presumptive POPs. 4.4 Inherent Problems in the Application of Numerical and other Criteria
Because of the inherent biological variation as well the normal statistical variation inherent in any physical or chemical measurement all numerical criteria must be applied with caution and judgement. Deficiencies in the scientific database for a substance may necessitate caution in using single numbers outside their proper context. The uncertainty related to any kind of scientific measurement is of particular importance in cases where the database consists of a single measurement. Similarly, numbers close to the cut-off values must be thoroughly assessed, regardless of whether they are slightly below or slightly above the cutoff. When several criteria are judged together one might consider a certain substance as fulfilling the criteria if two or more of the criteria are more than adequately fulfilled while one criterion may be just marginally fulfilled or not quite fulfilled. A more generic problem is the lack of appropriate methods for predicting what actually happens in the environment.While at present there is a lack of mutually agreed assessment procedures for chemicals this is something that needs to be developed in the process of applying the criteria. With regard to data quality and validity, data might have been generated under a wide variety of test methods and conditions. All available data should be considered, and scientific judgement should be applied by putting more empha-
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sis on results generated under standardized conditions using widely accepted test methods and laboratory practices. Results obtained under non-standardized test conditions or without recognized test methods might also be considered, as they might sometimes be more appropriate to the issues of concern. Uncertainties in the database frequently give rise to different interpretations between countries or stakeholders.An important part of the criteria development process is to make sure that these divergences are eliminated to the fullest extent possible and that the reasons for any remaining differences are thoroughly understood. A prerequisite for this to happen is a clear understanding of how political considerations, particularly in the field of science policy, influence assessments of hazard and risk. Countries may make various assumptions in their interpretation of scientific data, for example, accepting one well-conducted lifetime study in one species as sufficient evidence of chronic effects, or always taking the “worst” value for an effect parameter. This might reflect the level of protection desired in a country. In the face of the number of possible candidates and the insurmountable costs of testing all substances to a satisfactory degree, predictive tools, e.g., accurate screening methods and fate modeling to identify probable POPs with a potential for long-range transport need to be developed. In applying criteria the strengths and weaknesses of existing methods should be identified and recommendations for method improvement made, as appropriate. The ultimate proof of long-range environmental transport is the presence of POPs in remote environments, such as the Arctic, as evidenced by monitoring data. There is a need for further development of existing monitoring programmes and of establishing such programmes in regions where they do not exist, including looking for new possible POPs. However, monitoring programmes will only reveal pollution that already has occurred and cannot substitute for taking proper preventative action at the source against substances with suspected or confirmed POPs properties. 4.5 Bio-Diversity and Other Factors
Special considerations may influence the application of criteria, such as the need to conserve bio-diversity and the protection of endangered species. For instance, it might be necessary to apply stricter cut-off values for POPs when the diversity of economically, socially and culturally important biota is at stake, or where individual species are threatened [12].
5 Criteria in the Global Negotiating Process The Criteria Expert Group established by the Intergovernmental Negotiating Committee quickly came to an agreement on the properties to consider for screening criteria [4, 5]. For an initial assessment data on persistence, bio-accu-
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mulation, potential for long-range transport and adverse effects should be considered. In view of the multi-compartment behaviour of these substances, persistence in water, soil and sediments were considered of equal importance. Persistence in air should be considered in conjunction with the potential for long-range transport for substances that signficantly migrate through the air and for such substances the half-life in air should be greater than 2 days. In addition, volatility was viewed as a property that should be considered together with other physical and chemical properties of importance for determining the environmental fate of a substance. For persistence in water, soil and sediments numerical cut-off values for halflives in these media were proposed. For half-life in water, two months was agreed, while for soil and sediment there was agreement to use a half-life of six months. Similarly, for bio-accumulation there was agreement to use a cut-off value of 5000 for BCF/BAF in aquatic species. In absence of BCF/BAF data, logKow should be greater than 5. It should be noted that high bio-accumulation in other species or high toxicity or eco-toxicity might be sufficient to fulfill the criteria for bio-accumulation. There is also agreement that when the assessment passes on to the more in-depth stage measured values of BCF/BAF are needed, i.e., logKow as a substitute will not be sufficient. For the other two criteria; potential for long-range transport and adverse effects, no numerical values have been suggested. With regard to environmental fate there are many environmental fate properties and data which are relevant for assessing long-range environmental transport. Those properties and data, many of which were relevant to several of those areas, may be grouped into those relevant for transport (vapour pressure, Henry’s Law constant; water solubility; studies relevant to local, regional, or global environmental transport; particle dispersion; density; etc.), transfer [log Kow, other partition coefficients, water solubility, molecular weight, molecular size, bio-concentration factor (BCF), bio-accumulation factor (BAF), etc.], and transformations (molecular structure, half-lives in various environmental media, and many of the properties and data noted above). In addition a broad interpretation of the terms “toxicity” and “eco-toxicity” should be used. These terms are intended to cover a broad scope of adverse endpoints as might be determined in a variety of controlled in vivo and in vitro laboratory studies, field studies of biota, and epidemiology studies. Furthermore, effects observed or reported could be associated with a variety of single, multiple, intermittent or continuous exposures, could be immediate or delayed, or could be short-term or chronic in their duration. The experts agreed that a certain substance may be considered as fulfilling the criteria if two or more of the criteria are more than adequately fulfilled while one criterion may be just marginally fulfilled or not quite fulfilled. It was also agreed that the assessment process should include the consideration of transformation products of the substance that possessed POPs characteristics. In this regard organic substances that are not in themselves POPs, but whose transformation products satisfy the criteria should be considered.
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The final text, agreed to at the last meeting of the Intergovernmental Negotiating Committee, is presented in the Appendix to this paper.
6 Concluding Remarks A substantial scientific body of knowledge is available to guide us in designing a screening criteria process in which suspected substances may be judged in a step-wise procedure going from simple numerical values for individual properties to a full and comprehensive evaluation of all its impacts. Scientific developments in chemistry, biology, toxicology and related fields can only improve upon the present process to make it more robust and useful for the future. However, at present attempts at developing exact, science-based criteria for identifying with certitude all persistent organic pollutants warranting global action and assigning rigid numerical cut-off values for all selected properties are likely to fail because of the limited scientific knowledge of the underlying processes.
Annex D of the Stockholm Convention on POPs Information Requirements and Screening Criteria
1. A Party submitting a proposal to list a substance in Annexes A, B or C shall identify the chemical in the manner described in subparagraph (a) below and provide the information on the chemical, and its transformation products where relevant, relating to the criteria set out in subparagraphs (b) to (e): (a) Chemical identity, including: (i) Names: trade name or names, commercial name or names and synonyms, Chemical Abstracts Service (CAS) Registry number, International Union of Pure and Applied Chemistry (IUPAC) name; and (ii) Structure, including specification of isomers, where applicable, and the structure of the chemical class. (b) Persistence: (i) Evidence that the half-life of the chemical in water is greater than two months, or that its half-life in soil is greater than six months, or that its half-life in sediment is greater than six months; or (ii) Evidence that the chemical is otherwise sufficiently persistent to justify its consideration within the scope of this Convention; (c) Bio-accumulation: (i) Evidence that the bio-concentration factor or bio-accumulation factor in aquatic species for the chemical is greater than 5,000 or, in the absence of BCF and BAF data, that the log Kow is greater than 5; (ii) Evidence that a chemical presents other reasons for concern, such as high bio-accumulation in other species, high toxicity or ecotoxicity; or
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(iii) Monitoring data in biota indicating that the bio-accumulation potential of the chemical is sufficient to justify consideration within the scope of this Convention; (d) Potential for long-range environmental transport: (i) Measured levels of the chemical in locations distant from the sources of its release that are of potential concern; (ii) Monitoring data showing that long-range environmental transport of the chemical, with the potential for transfer to a receiving environment, may have occurred via air, water or migratory species; or (iii) Environmental fate properties and/or model results that demonstrate that the chemical has a potential for long-range environmental transport through air, water or migratory species, with the potential for transfer to a receiving environment in locations distant from the sources of its release. For a chemical that migrates significantly through the air, its half-life in air should be greater than two days; and (e) Adverse effects: (i) Evidence of adverse effects to human health or to the environment that justifies consideration of the chemical within the scope of this Convention; or (ii) Toxicity or ecotoxicity data that indicate the potential for damage to human health or to the environment. 2. The proposing Party shall provide a statement of the reasons for concern, including, where possible, a comparison of toxicity or ecotoxicity data with detected or predicted levels of a chemical resulting or anticipated from its long-range environmental transport, and a short statement indicating the need for global control. 3. The proposing Party shall, to the extent possible and taking into account its capabilities, provide additional information to support the review of the proposal referred to in paragraph 6 of Article 8. In developing such a proposal, a Party may draw on technical expertise from any source.
Annex E Information Requirements for the Risk Profile
The purpose of the review is to evaluate whether the chemical is likely, as a result of its long-range environmental transport, to lead to significant adverse human health and/or environmental effects, such that global action is warranted. For this purpose, a risk profile shall be developed which further elaborates on, and evaluates, the information referred to in Annex D and includes, as far as possible, the following types of information: (a) Sources, including as appropriate: (i) production data, including quantity and location; (ii) uses; and (iii) releases, such as discharges, losses and emissions;
44
B.A. Wahlström
(b) Hazard assessment for endpoint or endpoints of concern: the assessment should include a consideration of toxicological interactions involving multiple chemicals; (c) Environmental fate, including data and information on the chemical and physical properties and persistence of a chemical and how they are linked to its environmental transport, transfer within and between environmental compartments, degradation and transformation to other chemicals. A determination of BCF or BAF, based on measured values, shall be available, except when monitoring data are judged to meet this need; (d) Monitoring data; (e) Exposure in local areas and, in particular, as a result of long-range environmental transport, and including information regarding bio-availability; (f) National and international risk evaluations, assessments or profiles and labelling information and hazard classifications, as available; and (g) Status of the chemical under international conventions.
Annex F Information on Socio-Economic Considerations
An evaluation should be undertaken regarding control measures, for chemicals under consideration for inclusion in this Convention encompassing the full range of options, including management and elimination. For this purpose, relevant information should be provided relating to socio-economic considerations associated with control measures to enable a decision to be taken by the Conference of the Parties. Such information should reflect due regard for differing capabilities and conditions among Parties and should include consideration of the following indicative list of items: (a) Efficacy and efficiency of control measures in meeting risk reduction goals: (i) Technical feasibility; and (ii) Costs, including environmental and health costs; (b) Alternatives (products and processes): (i) Technical feasibility; (ii) Costs, including environmental and health costs; (iii) Efficacy; (iv) Risk; (v) Availability; (vi) Technical feasibility; and (vii) Accessibility; (c) Positive and/or negative impacts on society of implementing control measures: (i) Health, including public, environmental and occupational health; (ii) Agriculture, including aquaculture and forestry; (iii) Biota (biodiversity);
Criteria for Additional New POPs
45
(iv) Economic aspects; (v) Movement towards sustainable development; and (vi) Social costs; (d) Waste and disposal implications (in particular, obsolete stocks of pesticides and clean-up of contaminated sites): (i) Technical feasibility; and (ii) Cost; (e) Access to information and public education; (f) Status of control and monitoring capacity; and (g) Any national or regional control actions taken, including information on alternatives, and other relevant risk management information.
7 References 1. UNEP Governing Council (1995) Decision 18/32 2. IFCS ad hoc Working Group on Persistent Organic Pollutants (1996) Manila, The Philippines 3. UNEP Governing Council (1997) Decision 19/13C 4. UNEP/POPS/INC/CEG/1/3 (1998) Report of first meeting of Criteria Expert Group for POPs. Bangkok, Thailand 5. UNEP/POPS/INC/CEG/2/3 (1999) Report of second meeting of the Criteria Expert Group for POPs. Vienna, Austria 6. UNECE/LRTAP/EB (1998) Decision 2, Geneva, Switzerland 7. UNECE Protocol to the 1979 Convention on Long-range Transboundary Air Pollution on Persistent Organic Pollutants (1998) Aarhus, Denmark 8. Evaluation of Persistence and Long-Range Transport of Organic Chemicals in the Environment, Klecka GM, Boethling RS, Franklin J, Grady CPL Jr, Graham D, Howard PH, Kannan K, Larson RJ, Mackay D, Muir D,Van de Meent D (1998) Proceedings of a SETAC Pellston Workshop on Persistence and Long-Range Transport of Organic Chemicals in the Environment, 13–19 July, 1998, Fairmont Hot Springs, British Columbia, Canada. Society of Environmental Toxicology and Chemistry, Pensacola, FL, USA. 9. Process for Identifying Candidate Substances for Regional Action under the Sound Management of Chemicals Initiative (1997), Montréal, Canada 10. Toxic Substances Management Policy (1995) Ottawa, Canada 11. New Guidelines for Chemicals Policy (2000) Ministry of Environment Stockholm, Sweden 12. UNEP/POPS/INC.1/6 Note from the Secretariat (1998) Montreal, Canada 13. OECD Guidelines for the Testing of Chemicals (1981) Paris, France 14. OECD Principles of Good Laboratory Practice, as revised in 1997 (1998) Paris, France 15. OECD Council Decision on the Mutual Acceptance of Data in the Assessment of Chemicals C(81)30 (Final) (1981) Paris, France 16. WHO Recommended Classification of Pesticides by Hazard (2001) Geneva, Switzerland
CHAPTER 4
Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex Vladimir Zitko 114 Reed Ave, St. Andrews, NB, E5B 1A1, Canada E-mail:
[email protected] This chapter provides an overview of history, chemistry, environmental fate and effects of DDT and of the cyclodiene pesticides aldrin, dieldrin, endrin, and mirex, and their metabolites and degradation products. These pesticides are, for the purpose of this review, summarily called the ‘classic organochlorines’ (COC). All cyclodiene COC have been practically phased out. DDT is still used in several countries, to some extent in agriculture, but primarily, to control malaria. Common structural features of COC are the presence of several chlorine atoms and a rigid shape of the molecule. Common properties include very low solubility in water and high solubility in lipids, low but significant vapor pressure, and a strong resistance to degradation. The consequences of this combination of properties include a wide distribution and persistence in the environment and accumulation in biota. A prolonged presence in biota results in a number of chronic effects, not anticipated from short-term toxicity studies. COC and similar compounds are not likely to be again released intentionally into the environment; thus this chapter documents a history which will not, hopefully, be repeated. The story should serve as example of difficulties in anticipating environmental effects of chemicals, unexpected consequences, and changing attitudes and terms of reference. Studies of COC contributed a great deal to the understanding of the behaviour of chemicals in the environment; however, nothing can be done about the trace concentrations of COC now present there. An important lesson has been learned and it is time to start paying attention to the detection, behaviour, and effects of many other chemicals released into the environment. Keywords: Production, Toxicity, Bioaccumulation, Trends
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1
Introduction
2
Structure and Properties
3
Environmental Concentrations
3.1 3.2 3.3 3.4 3.5 3.6 3.6.1
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The Handbook of Environmental Chemistry Vol. 3, Part O Persistent Organic Pollutants (ed. by H. Fiedler) © Springer-Verlag Berlin Heidelberg 2003
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V. Zitko
3.6.2 3.6.3 3.7
Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Marine Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Humans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4
DDT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.1 4.2 4.3 4.3.1 4.3.2 4.3.3 4.3.4
History . . . . . . . . . . . . . Production . . . . . . . . . . . Effects . . . . . . . . . . . . . . Mode of Action . . . . . . . . . Structure-Activity Relationships Transformations . . . . . . . . Toxicology . . . . . . . . . . .
5
Aldrin and Dieldrin
5.1 5.2 5.3
History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Mode of Action, Transformations, and Toxicology . . . . . . . . . 79
6
Endrin
6.1 6.2 6.3
History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Transformations and Toxicology . . . . . . . . . . . . . . . . . . 81
7
Mirex
7.1 7.2 7.3
History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Toxicology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
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Closing Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
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References
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1 Introduction DDT was the first chemical found to be remarkably active against a number of insect pests. Its first large-scale use towards the end of World War II was such a success that the discoverer of the insecticidal properties of DDT, Paul Müller, received the Nobel Prize in 1948. One of the valued properties of DDT was its persistence. There was no need for frequent applications and, in addition, DDT has very low acute toxicity in mammals. For at least another 15 years nobody thought of food chains, bioaccumulation, chronic toxicity, and concentrations of residues in the µg/g (ppm) range. Gas chromatography was a curiosity, the electron capture detector was not invented until 1960 [37], and the analytical chemistry was comfortable with concentrations in the mg% (mg/100 g=10 ppm) range. Even in
Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex
49
1967, gas chromatography with electron capture detection, thin layer chromatography, and infrared spectrophotometry were the methods of choice to study environmental fate of DDT and metabolites [182]. The definitive confirmation of many pesticide residues was not possible before the introduction of a mass spectrometer as a detector in gas chromatography, in 1971 [18]. A very interesting history of residue analyses in wildlife, is provided by Keith [109]. It was thought that the presence of chlorine atoms in the molecule of DDT may be a source of its insecticidal activity, and attempts to prepare other such compounds were soon underway. Further impetus to this effort were cases of insect resistance to DDT that started to appear within a few years after large-scale DDT applications. The cyclodiene pesticides chlordane, aldrin, dieldrin, and endrin appeared on the scene and were, somewhat later, followed by mirex and its derivative, chlordecone. These insecticides also have a remarkable insecticidal activity and their typical agricultural application rate ranged from less than 0.5 kg/ha to 2 kg/ha, as compared to 5 kg/ha to 10 kg/ha, or even 40–50 kg/ha in northern orchards, for DDT. However, the cyclodienes have much higher mammalian toxicity than DDT and their use has been somewhat more limited. After a few years, the presence of DDT in human tissues was noticed and caused some concern. Between 1956 and 1961 a large number of bird kills was attributed to seeds treated with aldrin and dieldrin [169].At the same time, kills of birds, fish, and mammals were observed, not only in pesticide-treated areas but also at more distant sites. These incidents together with improvements in analytical techniques led to a better understanding of environmental effects and fate of pesticides. All these were summarized by Rachel Carson in her book Silent Spring in 1962. By the early 1970s, p,p′-DDE was discovered as the agent responsible for the eggshell thinning in a number of avian species [28]. Gradually, restrictions were imposed on the indiscriminate use of pesticides, as gas chromatography with the electron capture detector revealed a widespread contamination of humans and the environment by DDT and its main metabolites, DDE and DDD, and by dieldrin. A complication was encountered by the presence of a number of unknown peaks, some very close or overlapping, the peaks of DDT and its metabolites. Substances causing these peaks were identified in 1967 by Jensen as polychlorinated biphenyls (PCBs). It is likely that the presence of PCBs resulted in some erroneously high, early-reported concentrations, particularly of p,p′-DDE, but also of p,p′-DDD and p,p′-DDT. Even without considering PCBs, the separation of p,p′-DDE and dieldrin by gas chromatography on packed columns was difficult, and relatively low concentrations of the latter may have remained undetected. It took another ten years and the advent of gas chromatography on capillary columns and the mass analyzer detector, to achieve a reliable identification and confirmation of organochlorine pesticides. Many orders of magnitude increase in sensitivity, attained by the new analytical techniques, revealed a widespread presence of these compounds in the environment. Organochlorine pesticides were detected even in the most remote parts of the environment and their global circulation patterns were noticed. At this stage the term organochlorine pesticides covered the COC (Classic organochlorine compounds, an acronym introduced for convenience for the title pesticides of this
50
V. Zitko
chapter) and their metabolites, and, in addition, the hexachlorocyclohexanes and toxaphene. Hexachlorobenzene and PCBs were later included because of their equally widespread presence in the environment, and hexachlorobenzene had some applications as a fungicide. The group was referred to as the organochlorine compounds. Recently, this group was expanded and a new term was introduced, the Persistent Organic Pollutants (POPs). This new group is defined on the basis of environmental properties of its members – persistence, bioaccumulation, and adverse effects, and a global, legally-binding international action on POPs is promulgated. As of 1999, the international action for COC includes a complete phase-out of aldrin and endrin, and a partial phase-out of dieldrin and mirex. The case of DDT is still under discussion, mainly because of DDT’s importance in the control of malaria. In parallel with the persistence-based definition of POPs, another group of compounds, defined by their effects on the endocrine system, the Endocrine Disrupting Chemicals (EDCs), was formed. EDCs include COC and, in addition, branched-chain alkyl phenols and other chemicals grouped by their effects rather than by chemical structure or properties. In this connection it is interesting to note that the estrogenic activity of o,p′-DDT, a minor component of technical DDT, was noticed already in 1968, but did not receive much attention at that time. The endocrine disrupting activity of p,p′DDE, a major DDT metabolite and degradation product, displayed by the inhibition of the androgen receptor androgen binding, was discovered only recently [110]. For the last 30 years, about 800 papers per year were published on some aspects of DDT, followed by approximately 200, 130, 90, and 40 papers per year, on the subject of dieldrin, aldrin, endrin, and mirex, respectively (Table 1). The vast majority of the papers deals with concentrations of these compounds in various environmental compartments. The following frequent topic is toxicology, which describes chronic and, increasingly, subtle effects. Relatively few papers investigate time trends of the concentrations. Because of limited space, it is impossible to refer in this chapter to more than a few publications. Consequently, some statements are presented without references. When given, references were selected
Table 1. Average number of papers abstracted by Chemical Abstracts
Years
SDDT
Aldrin
Dieldrin
Endrin
Mirex
1967–1969 1970–1974 1975–1981 1982–1987 1988–1989 1990–1994 1995 1996 1997 1998 1999
494 835 742 536 717 643 853 873 977 846 1115
122 133 104 94 132 140 150 157 170 125 130
192 242 197 129 180 190 213 219 268 227 265
97 89 80 49 82 88 119 110 120 107 107
4 14 42 37 39 46 54 54 36 49 58
Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex
51
somewhat arbitrarily to cover the literature of the past 40–50 years and to provide a picture of increasing knowledge and of developing environmental awareness and insight. A more general discussion of the latter was published recently [216].
2 Structure and Properties Chemical and common names of COC, as well as their Chemical Abstracts Registry Numbers are in Table 2, properties of environmental interest are in Table 3 for COC as well as for some of their degradation products.‘Benchmark’ toxicity data, illustrated by toxicity to rats, are in Table 4. Structural formulae, metabolites and degradation products are mentioned in sections dealing with the individual pesticides. The solubility of COC in water is extremely low. The determination of such low solubilities is fraught with considerable difficulties. Its is therefore not surprising that the published estimates differ by as much as orders of magnitude. The values, provided in Table 3, are for the most part geometric means of values, colTable 2. Chemical and common names
p,p′-DDT p,p′-DDD Aldrin
Dieldrin
Endrin
Mirex
1,1,1-Trichloro-2,2-bis(4-chlorophenyl)ethane (IUPAC) 1,1′-(2,2,2-Trichloroethylidene)bis[4-chlorobenzene] (CA) CA RN 50-29-3 1,1-Dichloro-2,2-bis(4-chlorpohenyl)ethane (IUPAC) 1,1′-(2,2-Dichloroethylidene)bis[4-chlorobenzene] (CA) CA RN 72-54-8 (1R,4S,4aS,5S,8R,8aR)-1,2,3,4,10,10-Hexachloro-1,4,4a,5,8,8a-hexahydro1,4:5,8-dimethanonaphthalene (IUPAC) (1a, 4a,4ab,5a,8a,8ab)-1,2,3,4,10,10-Hexachloro-1,4,4a,5,8,8a-hexahydro1,4:5,8-dimethanonaphthalene (CA) HHDN (common, pure compound) Aldrin (material containing 95% HHDN) CA RN 309-00-2 (1R,4S,4aS,5R,6R,7S,8S,8aR)-1,2,3,4,10,10-Hexachloro-1,4,4a,5,6,7,8,8aoctahydro-6,7-epoxy-1,4:5,8-dimethanonaphthalene (IUPAC) (1aa,2β,2aa,3b,6β,6aa,7b,7aa)-3,4,5,6,9,9-Hexachloro-1a,2,2a,3,6,6a,7,7aoctahydri-2,7:3,6-dimethanonaphth[2,3-b]oxirene HEOD (common, pure compound) Dieldrin (material containing >85% HEOD) CA RN 60-57-1 (1R,4S,4aS,5S,6S,7R,8R,8aR)-1,2,3,4,10,10-Hexachloro-1,4,4a,5,6,7,8,8aoctahydro-6,7-epoxy-1,4:5,8-dimethanonaphthalele (IUPAC) (1aa,2b,2ab,3a,6a,6ab,7b,7aa)-3,4,5,6,9,9-Hexachloro-1a,2,2a,3,6,6a,7,7aoctahydro-2,7:3,6-dimethanonaphth[2,3-b]oxirene (CA) CA RN 72-20-8 Dodecachloropentacyclo[5.3.0.02,6.03,9.04,8]decane (IUPAC) 1,1a,2,2,3,3a,4,5,5,5a,5b,6-dodecachlorooctahydro-1,3,4-metheno-1Hcyclobuta[cd]pentalene (CA) CA RN 2385-85-5
2.39E –04
7.52E–01
6.79
1.41E –05
Henry’s Law constant, 1.80E+00 Pa.m3/mole
6.19
5.39
Solubility in water, mole/l
logKow
logKoc
6.62
8.5 E –02
1.90E–07
1.35E–06
355
5.00E –03
109
mp
Solubility in water, mg/l
355
MW
789-02-6
o,p-DDT
vp mmHg, 20 °C
50-29-3
CA RN
p,p-DDT
Table 3. Properties of environmental interest
6.64
7.00
2.50E +01
3.46E–05
1.10E–02
6.50E –06
89
318
72-55-9
p,p-DDE
5.78
6.00
2.02E +01
4.09E–05
1.40E–01
6.20E –06
318
3424-82-6
o,p-DDE
5.89
6.02
1.28E +00
1.41E–04
4.50E–02
1.35E –06
109
320
72-54-8
DDD
4.98
5.30
1.07E +01
8.22E–05
3.00E–02
6.60E –06
104–104.5
365
309-00-2
Aldrin
3.62E–04
2.50E–01
3.00E –06
228
381
72-20-8
Endrin
3.23
3.50
4.93
5.20
1.13E +00 1.10E +00
3.54E–04
1.35E–01
3.00E –06
175–176
381
60-57-1
Dieldrin
Chlordecone
491 350
7.38
6.89
5.15
5.41
3.64E+00 5.45E–03
1.10E–05 5.50E–03
6.00E–03 2.70E+00
3.00E–07 2.25E–07
485
546
2385-85-5 143-50-0
Mirex
52 V. Zitko
53
Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex Table 4. Oral toxicity to rats [72]
Aldrin p,p′-DDT p,p′-DDE Dieldrin Endrin Mirex Chlordecone
LD50 (mg/kg)
LD1(mg/kg)
Lowest dose to kill (mg/kg)
Male
Female
Male
Female
Male
Female
39 113 880 46 18 740 125
60 118 1240 46 8 600 125
18 52 360 25 5 200 92
27 80 460 25 5 270 92
25 75 750 30 10 400 100
40 100 500 30 6 500 125
lated in [179]. There do not seem to be accurate values for the aqueous solubility of mirex and chlordecone. The vapor pressures of COC are also low, but the ratio of a low vapor pressure to an extremely low solubility in water yields high values of the Henry’s law constants, which determine the distribution of organic chemicals in environmental compartments (see, for example, [129]). Similarly, the values of the octanol/water distribution coefficients are, with the exception of dieldrin, within the ‘optimal range’ (log Kow 5–7) for bioaccumulation (see, for example, [158]).At the same time, the values of adsorption coefficient on organic carbon are also high and indicate that these compounds are strongly bound by organic matter in soil and aquatic sediments. This strong binding extends to dissolved high-molecular weight organic materials, described as fulvic acid, humic acid, or natural organic matter [184]. Such substances may influence strongly the solubility of COC in water. For example, the solubility of p,p′-DDT increases from 5 mg/l in the absence to 35 mg/l in the presence of soil humic acid at 100 mg/l [46]. At the same time, the bioavailability may decrease because of binding of the pesticides to the natural organic matter. However, this subject has not been studied in great detail [26], although it has been suggested as an explanation of decreased bioaccumulation of very highly lipophilic compounds [209]. Estimates of the half-life of COC in the environment range from 365 days for aldrin to 4300 days for endrin. In environmental context, half-lives are difficult to define and the mentioned values are only an indication of the extreme persistence of COC. Models, such as those developed by Mackay [129], present a better picture of the environmental distribution and behaviour. As can be seen from the example of acute toxicity to rats, the toxicity of aldrin, dieldrin, and endrin is considerably higher than that of DDT. The toxicity of mirex approximates that of DDT. On the other hand, the metabolite of mirex, chlordecone, also used as a pesticide on its own, is as toxic as DDT. The toxicity of all the pesticides to aquatic biota is very high. The distribution of toxicity values to fish and crustaceans, expressed in terms of LC50 or IC50, re-drawn from data compiled in [210], is presented in Fig. 1. With the exception of the toxicity of aldrin to crustaceans, the distributions are nearly parallel, with endrin being the most toxic. COC are acutely toxic to practically all species of fish and crustaceans at concentrations below 100 mg/l.
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V. Zitko
Fig. 1. A summary of aquatic toxicity data, adapted from [210]. A, ac, d, dc, e, ec, ddt, ddtc in-
dicate toxicities of aldrin, dieldrin, endrin and DDT to fish and crustaceans, respectively
According to the toxicity ranking factor [69], the reciprocal of the product of Henry’s Law constant and the acute toxicity LC50, the aquatic toxicity hazard decreases in the order endrin dieldrin>DDT>aldrin.
3 Environmental Concentrations The most frequently reported concentrations are those of p,p′-DDE and p,p′DDT, followed by dieldrin and mirex. The o,p′-isomers of the DDT group, aldrin and endrin are reported much less frequently.Aldrin is seldom found because of its rapid conversion into dieldrin. Endrin has not attracted much attention because of its relatively small-scale use and very low concentrations, yielding a signal possibly hidden in the background of the sample’s analytical signal. The scatter of the measured concentrations is very large, partly due to the variability, typical of environmental matrices, partly because of the complicated analytical techniques, involving in most cases a lengthy cleanup. In addition, the measurement of concentrations in the part-per trillion (pg/g) through part-perbillion (ng/g) to part-per-million (µg/g) is, according to the Horwitz principle, associated with standard deviations ranging from 10–100% [9]. It is important to confirm findings of unexpected presence or of unusually high concentrations. Thus, for example, endrin in concentrations of 1–141 ng/g wet weight was reported in the muscle of a cyprinid fish Barbus xanthopterus, and in concentrations of 11–236 ng/g wet weight in the muscle of Indian shad (Tenualosa ilisha)
Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex
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from Iraq [63]. These concentrations are in the same range as those of SDDT, measured in the same fish. Similarly, o,p′-DDD was reported in average concentrations ranging from 111 to 148 ng/g wet weight in eggs of cormorants (Phalacrocorax carbo sinensis) in Greece [116]. For comparison, the average concentrations of p,p′-DDE ranged from not detectable to 0.42 ng/g wet weight. The authors’ explanation is that the elevated concentrations of o,p′-DDD “are due to its presence in zooplankton and in the water column”. It is more likely that an error was propagated through the data evaluation and publication process and, probably, the concentrations of these two compounds were transposed. This emphasizes the need for a careful quality control of the whole process of residue analysis. The results may be reported in µg, ng, or, sometimes, pg, per g or kg wet, dry, or lipid weight, which adds to the confusion, particularly when the content of dry matter or lipid is not stated. In addition, several different methods may be used to determine the lipid content and yield different results. Methylsulfonyl metabolites of p,p′-DDE are increasingly being reported, particularly in marine mammals and aquatic birds. Tris(4-chlorophenyl)methane (TCPM) and tris(4-chlorophenyl)methanol (TCPMOH) have also been found recently in the environment. There is some evidence that they may have originated from technical DDT and some authors found a correlation between the concentrations of TCPM/TCPMOH and DDT. However, there are also excellent correlations between the concentrations of PCBs and DDT, which, of course mean that both substances behave similarly in the environment, not that PCBs originate from DDT. The determination of time trends of concentrations is very difficult and costly since it requires large number of analyses over many years. The results are affected by many factors [25]. These include biological variability, sampling protocol, frequency and duration of sampling, and, last but not least, changes in the measurement techniques. Thus, for example, the ratio of SDDT concentrations in the same samples of mussels, measured in 1999 to the concentrations obtained in 1977 ranged from 0.03 to 7.1, with a mean of 0.6 [122]. 3.1 Air
The concentrations of COC are usually in tens of pg/m3, but may reach hundreds or thousands in areas of heavy agricultural use of pesticides. In 1971 Woodwell et al. [225] estimated the concentration of DDT in the atmosphere, based on the United States production to that date (Fig. 2). The solid line assumes DDT production in the United States declining to zero in 1974, the dotted line corresponds to continuing production. Concentrations actually measured over the oceans are up to several orders of magnitude below the predicted ones, but approach them in localized areas of high DDT use. The measurement of extremely low concentrations is difficult. Consequently, several ‘surrogate’ matrices, such as pine needles, moss, and tree bark were suggested. The concentrations of SDDT (in this chapter, the term ΣDDT means the sum of the concentrations of p,p′-DDT and its metabolites, most frequently p,p′-DDE and p,p′-DDD. Relatively seldom it also includes some of the o,p′-isomers) in pine needle wax from Sweden and Norway
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V. Zitko
Fig. 2. Concentration of DDT in the troposphere [101, 171, 225]. Solid and dotted lines are model estimates, developed in 1971. The former assumes DDT production ending in 1974, the dotted line, continuing production of DDT. Vertical lines indicate ranges of concentrations actually measured [8, 64, 101, 22, 23]
ranged from 0.12–0.43 ng/g of fresh needle and the concentrations declined from 1984 to 1986. The concentration range was 0.25–0.65 ng/g for Switzerland, Germany, and Denmark and the concentrations declined similarly to those in Sweden. In Poland, in 1985 and 1986 the concentrations ranged from 0.3–2.48 ng/g [65]. In the Czech republic during 1988–1994, moss (Hypnum cupressiforme L. ex Hedw.) accumulated higher concentrations of COC than pine needles, with a range from
