Next Global Alert: Persistent Organic Pesticides

The world should do for pesticides what it did for chemicals that destroy the ozone layer. It needs a global phase-out of dangerous agricultural chemicals. Their misuse has created a global environmental hazard on a scale to match that caused by the chlorofluorocarbons (CFCs) that attack the ozone layer.

Use of some of these farm chemicals is not allowed or is severely restricted in the countries that produce them. But the producers can ship them out to other countries - especially developing countries. The resulting hazard transcends direct local or regional poisoning.

These chemicals do not stay put. They travel through air and water. They end up thousands of miles away from their points of use. They contaminate lakes and streams even in countries that ban their use. They pollute the Arctic.

This is why United Nations member nations, acting under the 1979 Geneva Convention on Long-Range Transboundary Air Pollution, are treating pesticide misuse as a global environmental danger. At a meeting in Washington last november, 110 of these nations agreed in principle on the need to phase out use of the worst chemical offenders.

Since then, the treaty's negotiating group has been exploring ways to implement such a ban. The group reported on this last month at the UN Intergovernmental Forum on Chemical Safety in Canberra. Momentum now is building for a global ban on the most dangerous chemicals.

At issue are the persistent organic pesticides - the so-called POPs. They include DDT and other chemicals already banned in some countries. Their ability to take to the air is one of their most dangerous characteristics.

Research over the past several years appears to validate what scientists call the theory of global pesticide distillation. Used in the tropics and subtropics, the pesticides evaporate and travel northward. They condense in colder northern air and wash out into lakes, rivers, and soils. For example, Ronald Hites of Indiana University in Bloomington and Staci Simonich, a former Indiana graduate student now with Procter & Gamble in Cincinnati, studied tree bark specimens from 90 sites around the world. Their data not only documented widespread use of POP chemicals, it showed where they end up as well. Prof. Hites notes signs of DDT contamination in the midwestern and southwestern United States even though DDT use was banned in the United States in 1973. He blames what he calls the "global distillation effect."

Likewise, Canadian researchers such as biologist David Schindler with Alberta University have found dangerous levels of toxaphene in Yukon lakes. Both Canada and the United States banned toxaphene over a decade ago.

Eliminating dangerous POPs will be more difficult than curbing CFCs. There are many more chemicals and many more producers and users. Information on shipment and use of the chemicals is sketchy. Even the US government doesn't have complete records of what American pesticide producers ship overseas. Now that UN members are alert to this new global danger, however, action toward containing it could be forthcoming within the next couple of years.

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