Several chemicals, including one banned in the U.S., have been found in the Potomac River and its tributaries where pollution is suspected of causing some species of male fish to develop female sexual traits, scientists said.
Water samples taken at eight sites in West Virginia and blood plasma from smallmouth bass were analyzed as part of an investigation into the increase of so called "intersex fish" in which males produce immature eggs in their testes, the U.S. Geological Survey said.
A study released Wednesday said pesticides, flame retardants, personal-care products and a banned fungicide were identified in the water or the fish.
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"Endocrine disruptors of this type may contribute to the high percentage of male smallmouth bass found in the Potomac that exhibit female characteristics," the USGS said.
Potential sources of contamination include wastewater treatment plants, runoff from agricultural activities and industrial wastewater, the report said.
Further studies are planned to determine whether endocrine disruptors interfere with the reproduction and development of aquatic life, the USGS said.
The Environmental Protection Agency has been studying the issue of endocrine disruptors since 1996, but does not issue guidelines to water treatment plants for allowable levels of estrogenic compounds.