[Pharmwaste] Estrogen makes fish too feminine to reproduce
dldebiasi at deq.virginia.gov
Tue May 22 15:05:04 EDT 2007
Tuesday » May 22 » 2007
Estrogen makes fish too feminine to reproduce
Male minnows exposed to hormone found in sewage grew part-female sex organs: Study
CanWest News Service
Tuesday, May 22, 2007
Estrogen that goes down Canadian toilets -- some naturally from women, some from the birth-control pill -- is enough to make entire fish species too feminine to reproduce, a seven-year Canadian study shows.
Fish scientist Karen Kidd dripped small amounts of estrogen into a clean lake in northwestern Ontario over several years, just as if urine with the female hormone were running in via sewage from a nearby city. This constant hormone bath made male fathead minnows produce eggs in unnatural, part-female sex organs.
Even after she stopped adding estrogen and the water turned clean, the minnows almost completely disappeared for several years. Even small concentrations of estrogen can decimate wild fish populations, the University of New Brunswick biology professor concludes, even at levels found in some Canadian waters. She wouldn't name individual rivers.
And while the minnows were prone to fast extinction because of their short lifespan (about two years), she says bigger fish such as trout or pike might also be hurt if they are exposed for long enough.
The first dramatic news of "feminized" fish came from British rivers in the 1990s where male fish near sewage plants were producing eggs and carrying reproductive organs that were partly female.
"A lot of followup studies showed it was the natural estrogens that women excrete and then the synthetic estrogens in birth control pills that were the main causes of feminization in male fish," Kidd said.
"The pill is one of the most heavily prescribed pharmaceuticals in the world. There are over a million women on it in Canada."
She chose an unpolluted lake with healthy fish to learn what damage estrogen would cause.
Male minnows in water with estrogen just stopped looking male. Where they should have distinct colours and bumps at spawning time, they didn't have any visible sign of maleness.
"And then when you opened them up, their testes were much smaller than they should have been" -- about one-third the normal size. By the third year of adding estrogen to the lake, the testes had ovary-type tissue, and were producing eggs -- a condition called "intersex."
It's exactly what scientists had seen in the wild. The achievement is in reproducing this effect in a clean lake, proving that estrogen is the cause. Meanwhile, the female fish produced eggs too slowly.
The seven-year study was funded by Fisheries and Oceans Canada, where Kidd worked during most of it, and the American Chemistry Council. It's published today in the Proceedings of the National Academy of Sciences.
"A lot of our [pollution] regulations tend to be centred around chemicals that are persistent in the environment, and that accumulate in fish," she said. These include pesticides such as DDT and industrial PCB oils, both of which last for years.
Estrogen doesn't last long, but it, too, needs control through decent sewage treatment, she said. The bacteria in a sewage plant chew up estrogen effectively.
© Times Colonist (Victoria) 2007
Deborah L. DeBiasi
Email: dldebiasi at deq.virginia.gov
WEB site address: www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
Mail: P.O. Box 1105, Richmond, VA 23218 (NEW!)
Location: 629 E. Main Street, Richmond, VA 23219
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