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Reprinted from St Paul Pioneer Press 6/7/96

Pesticides pose danger in tandem

Threat to health far greater than scientists thought

ASSOCIATED PRESS
WASHINGTON

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 if it is confirmed in other labs, it could force a revolution in
the way that the environmental effects of chemicals are measured.
The study centered on endosulfan, dieldrin, toxaphene, and chlordane,
all pesticide chemicals that are known to turn on a gene that makes
estrogen in animals. 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 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 it was expected that combinations of the chemicals
would 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 (6/7) 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 EPA 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.

"We test the ingredients that go into the soup individually," she
said. The combination effect "is a very, very new issue for us."
Goldman said the McLachlan study will have to be verified in other
labs, including tests that screen the effects of the chemical
combinations on laboratory animals.

"It might not be as simple in whole animals as it is in cell lines,"
she said.
Other scientists also said that the work will have to be
double-checked by other researchers. But endocrinologist Wade Welshons
of the University of Missouri told Science: "It's a very important red
flag."

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