At Lake Apopka in Central Florida, the alligators have tiny penises. They run a third the size of normal alligator phalli and have significantly diminished sperm counts. In England, on the Lee River, feminized male fish have eggs as well as sperm in their gonads. And in the Great Lakes region, birds – including male herring gulls, terns and bald eagles – start exhibiting hermaphroditic changes after eating feminized fish.
Some scientists think the culprit in all of these gender-bending events might be exposure to ecoestrogens – a broad class of chemicals that mimic the hormone estrogen and disrupt normal functioning of the endocrine system, a body-wide network of hormone-producing glands that control things like growth and reproduction.