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Experts ask: When is a chemical too toxic to use?

Bangkok/Nairobi, 23 October 1998 - Leading experts on hazardous chemicals are meeting in Bangkok from 26 to 30 October to start identifying the scientific criteria that will be used for adding chemicals to an international watch list of so-called persistent organic pollutants, or POPs.

The list will be the basis for legal controls to reduce and eventually eliminate unacceptably toxic chemicals from the global environment. It will form part of a new treaty that is expected to be adopted by the year 2000.

"Governments have already agreed on the need to include 12 particularly dangerous POPs in the treaty right away," said Klaus Toepfer, Executive Director of the United Nations Environment Programme (UNEP), which is sponsoring the negotiations. "But for the treaty to be truly effective, we need a transparent and universally accepted system for deciding which other POPs are too dangerous for continued use."

The 12 POPs already on the list are aldrin, chlordane, DDT, dieldrin, dioxins, endrin, furans, heptachlor, hexachlorobenzene, mirex, PCBs, and toxaphene. Eventually dozens of other chemicals are likely to be added.

The Criteria Expert Group was established in July during the first round of POPs treaty talks, which were held in Montreal. In addition to toxicity, the Group will consider factors such as volatility (the ability of a chemical to evaporate into air), persistence (the ability to remain chemically stable and not decompose), long-range transport (POPs circulate globally through the atmosphere and by other means), and bioaccumulation (the ability to accumulate in living tissue at levels higher than those in the surrounding environment).

The experts will also discuss the procedural aspects of adding chemicals to a future legally binding instrument. One approach could involve a science-based standing committee that continually reviews and assesses chemicals against agreed criteria and makes proposals for additions to the treaty's Conference of the Parties. Another could be based on proposals for additions from the Parties to the Convention themselves, subject to agreed criteria and data requirements.

The Expert Group's first session is being hosted by the Government of the Kingdom of Thailand at the UN Conference Centre in Bangkok. Significant contributions towards covering the cost of the meeting were made by the United States, the United Kingdom and Switzerland. Some 100 experts are expected from 50 countries as well as a number of intergovernmental and non-governmental organizations. The meeting will be chaired by Ms. Fatoumata Yallow Ndoye of the Gambia and Reiner Arndt of Germany.

The launching of international treaty talks was inspired by a growing body of scientific evidence indicating that exposure to very low doses of certain POPs - which are among the most toxic substances ever created - can lead to cancer, damage to the central and peripheral nervous systems, diseases of the immune system, reproductive disorders, and interference with normal infant and child development.

Another concern behind the treaty negotiations is the growing accumulation of unwanted and obsolete stockpiles of pesticides and toxic chemicals, particularly in developing countries. Dump sites and toxic drums from the 1950s, '60s, and '70s are now decaying and leaching chemicals into the soil and poisoning water resources, wildlife, and people. A great deal of infrastructure and equipment such as electrical transformers and capacitors are also at or near the end of their useful lives and may leak dangerous chemicals such as PCBs.


Note to journalists: Additional data and documents are available via the Internet at

For more information, please contact:
Jim Willis in Geneva on
tel: +41-22-917-8170,
fax: +41-22-797-3460,

In Bangkok, contact the UNEP Regional Office for Asia and the Pacific on
tel. +66-2-829161,
fax: +66-2-280-3829,

UNEP News Release 1998/110

Sunday 25 Oct 1998
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