Gender Benders Feminize Fish. Who's Next?

Canada has a lotta lakes; so many that they can afford to take a few and do some destructive testing -"Entire small lakes are available to test hypotheses about freshwater ecosystems"-)(::Experimental Lakes) In one of them, Karen Kidd of the University of New Brunswick tossed in a heap of birth control pills (well, more accurately, she seeded a 34-hectare lake with 5 ppt 17∝-ethynylestradiol—the active ingredient in birth control pills) to see what would happen. (This is a big issue for TreeHuggers- we talk often about gender bender chemicals getting into our water and 85% of the hormones in birth control pills goes through the body and down the toilet. At the same time we say don't drink bottled water, drink tap. For cities with "closed loop" systems like those on the Great Lakes, we are, as Jacob so aptly put it, spiking the punch.)

She studied the effect of the hormones on the wonderfully named fathead minnow. According to Environmental Science and Technology:

"Within weeks of the first doses, male minnows started making vitellogenin, an egg-yolk protein typically produced by female fish. Within 2 years, the protein concentration reached up to 10,000 times normal levels. The exposure delayed sexual development of both sexes and because minnows spawn for just one season during their 2-year life, this caused the population to plummet toward collapse in just 3 years. The minnow population took 2 years to recover after researchers stopped adding estrogen.".::ES&T; and ::JS Online

Tags: Fish

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