Man-Made Chemicals May Put Strain on Fish

By David A. Fahrenthold
Washington Post Staff Writer
Tuesday, March 18, 2008

The Potomac River contains an array of man-made chemicals that could play havoc with animals' hormone systems, federal scientists have found in their best glimpse yet of the river's problems with a mysterious new class of pollutant.

The research, unveiled at a conference last week, found more than 10 of the compounds, including pesticides, herbicides and artificial fragrances. Through an accident of chemistry, formulas designed to kill bugs or add smell to soap might also interfere with vital signals in fish, amphibians and other creatures.

The scientists said they hoped this new research might explain one of the Potomac's most bizarre discoveries: Some male fish have begun growing eggs. Scientists said there was no evidence of a threat to human health.

Taken with a recent report that drinking water samples from the river contain traces of drugs, the results provide troubling evidence about the river's health. People living along the Potomac, the results showed, have widely tainted it with pollutants that scientists are just beginning to understand.

"The types of things we're finding are the types of things that are associated with everyday life," said David Alvarez, a U.S. Geological Survey research chemist who analyzed samples from the Potomac. The contaminants flow into the river from sewer plants and in rainwater washing off of farm fields and suburban lawns, he said.

"If it's something we're using, ultimately it's going to end up in the water," Alvarez said.

The chemicals in the study presented at the conference, held in Berkeley Springs, W.Va., are suspected by scientists to be "endocrine disruptors." This group of contaminants interferes with natural hormone systems, twisting or aborting the processes that hormones control. The conference was sponsored by the Metropolitan Washington Council of Governments.

Much about the compounds is still unclear, including which of them really do have bad effects.

In 1996, the Environmental Protection Agency was ordered by Congress to create a testing program to identify endocrine disruptors, but the tests have not begun.

Along the Potomac, researchers have long suspected that hormone-mimicking chemicals were the cause of the "intersex" fish. The first of these creatures, male fish with eggs growing in their sex organs, were noticed in a rural West Virginia tributary in 2003.

Follow-up studies have found the fish throughout the

watershed, including near the Woodrow Wilson Bridge.

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