Man-Made Chemicals May Put Strain on Fish

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.

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