National Geographic News, Reporting Your World Daily

Monday, November 23, 2009

Photo: Sex-Changing Chemicals Can Wipe Out Fish, Study Shows


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A new study involving the fathead minnow, pictured here, has shown that exposure to even low levels of estrogen caused males to develop eggs in their testes, while females experience delays in their reproductive cycles.

Estrogen used in birth-control pills can taint water supplies and pose serious threats to fish populations, the study's scientists say.

Illustration courtesy USFWS