New accord targets long-lived pollutants.

This week, negotiators from the United States and 121 other nations agreed to ban or phase out some of the world's most notorious chemicals. The 12 pollutants are renowned for their toxicity, long life, and propensity for leapfrogging around the world--often for decades.

The targeted compounds include dioxins and structurally related furans; polychlorinated biphenyls (PCBs); and the pesticides aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, and toxaphene.

The agreement, forged in Johannesburg, South Africa, will serve as the basis of a new United Nations treaty to protect people and wildlife from the cancers, birth defects, and other grave harms that persistent organic pollutants, or POPs, can cause.

The accord, reached early on Dec. 10, ended a week of confrontation over a few pivotal issues. Key among them was the amount of toxicity data that would be required for listing additional compounds under the treaty. At issue was a so-called precautionary principle. This tenet would permit some action against new POPs in coming years, even without scientific certainty about the extent of their toxicity.

The European Union and others had argued for language "that would appear to have allowed the nomination and listing of any chemical, regardless of whether there was science supporting [serious risks]," says Michael Walls, senior counsel for the American Chemistry Council of Arlington, Va., and an observer at the meeting. The United States, he notes, had lobbied for more evidence of risk before agents could be further considered for banning.

In the end, the envoys finessed their references to the precautionary principle. For instance, the final document notes that parties to the treaty, after evaluating risks of a compound--"including any scientific uncertainty [over risks]--shall decide in a precautionary manner whether to list the chemical."

It may sound bland, but Walls maintains that this phrasing allays "our concern that science could be ignored." Consequently, he told SCIENCE NEWS, "we are very, very pleased with the agreement" and anticipate that any U.S. administration would back it. Even major environmental groups, such as the World Wildlife Fund--U.S. and Greenpeace International, applauded the accord.

The proposed treaty establishes measures to curb the production, use, trade, and disposal of listed POPs. It also directs signatory governments to promote technologies to limit emissions of POPs and seek safer substitutes.

Most of the listed chemicals are slated for an immediate ban. Through 2025, however, the treaty would exempt PCBs contained in well-managed electrical transformers. It would also permit a couple dozen nations to continue using DDT to fight deadly insect-borne diseases, primarily malaria (SN: 7/1/00, p. 12).

Explains Michael Williams of the United Nations Environment Programme in Geneva, the negotiators made sure that "no one is going to get malaria because of this treaty." Every 3 years, however, DDT-exempted countries would have to report their efforts to wean themselves from the insecticide.

Aside from dioxins and furans, which are inadvertent by-products of some combustion (SN: 1/29/00, p. 70) and chemical-production processes, "the U.S. chemical industry has been out of the business of those POPs [now listed] for some time," Walls says. Many other countries, however, continue to use some of them. The treaty would permit temporary exemptions for specific compounds in countries lacking the money and technical ability to quickly adopt substitutes.

"This is the first time we have taken a global approach to toxic synthetic chemicals--asking ourselves which of them we can live without," notes Anne Platt McGinn of the WorldWatch Institute in Providence, R.I. As such, the treaty will spur a search for substitutes, she says. McGinn last month reviewed preliminary efforts by many governments to do just that. She titled her 92-page WorldWatch report "Why Poison Ourselves? A Precautionary Approach to Synthetic Chemicals."

Work on the new POPs treaty began 30 months ago (SN: 7/4/98, p. 6). Next May, the treaty will open for signing at a ceremony in Stockholm. It will become legally binding upon ratification by at least 50 nations.