Newspaper article St Louis Post-Dispatch (MO)

Pesticide Cited in New Study When Combined, Potency Increases

Newspaper article St Louis Post-Dispatch (MO)

Pesticide Cited in New Study When Combined, Potency Increases

Article excerpt

Pesticides that by themselves have been linked to breast cancer and male birth defects are up to 1,000 times more potent when combined, according to a study.

A federal environmental official called the finding "astonishing" and said that if confirmed in other labs, it could force a revolution in the way environmental effects of chemicals were measured.

The study centered on endosulfan, dieldrin, toxaphene and chlordane, all pesticides known to activate on a gene that makes estrogen in animals. The Environmental Protection Agency has banned or sharply limited the use of these chemicals.

Estrogen is a hormone that controls formation of female organs. A surplus of the hormone has been linked to breast cancer and to malformation of male sex organs.

By themselves, the pesticides have only a very weak effect on the estrogen gene, said John A. McLachlan of Tulane University, leader of a team that tested the chemicals.

"If you test them individually, you could almost conclude that they were non-estrogenic, almost inconsequential," he said. "But when we put them in combination, their potency jumped up 500- to 1,000-fold."

McLachlan said researchers had expected the combinations of the chemicals to be additive - that is, the effects of two chemicals together would equal the sum of the effects of the chemicals alone.

"Instead of one plus one equaling two, we found in some cases that one plus one equals a thousand," he said.

The study is to be published today in the journal Science.

"These findings are astonishing," said Dr. Lynn Goldman, chief of the Environmental Protection Agency's Office of Prevention, Pesticides and Toxic Substances. "The policy implications are enormous about how we screen environmental chemicals for estrogen effects."


"It is a very high priority for us to address the implications of this," she said.


The agency monitors testing of environment chemicals one at a time, said Goldman, and the agency now must consider how to test for effects of chemicals that might combine in the environment. …

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