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Posted by on November 14, 2005 at 16:19:12:
MALE fish with female characteristics - discovered off California - have raised fears that treated sewage can deform the sex organs of marine life. Scientists around the world have found sexual abnormalities in frogs, fish, alligators and other animals exposed to sewage effluent and industrial contaminants that mimic oestrogens and other hormones. But the latest research in the waters off Southern California is among the first to find such effects in ocean creatures. Eleven male bottom-dwelling fish out of 64 caught between Santa Monica and Huntington Beach had ovary tissue in their testes. No such sexual defects were found elsewhere off Southern California. Two other studies found other signs of feminised fish in the same areas. Two-thirds of male turbot and sole caught near Orange County's sewerage outfall had egg-producing proteins. And when males were exposed in a laboratory to ocean sediment collected off the Palos Verdes Peninsula and Huntington Beach - where huge volumes of sewage effluent are pumped out to sea - all of them developed female egg proteins. Dan Schlenk, an aquatic ecotoxicologist who co-wrote two of the three studies reported yesterday at a national conference, said it was clear that the ocean floor at sewerage outfalls was contaminated with oestrogenic compounds that are feminising fish. But effects on the overall health and abundance of fish populations and the rest of the marine ecosystem are unknown. "There's definitely oestrogenic activity out there, no doubt," Dr Schlenk said. "But whether it affects populations of the animals is the question we need to answer." Sewage effluent contains several dozen chemicals, natural and man-made, that can alter animal hormones, environmental scientists say. Women excrete natural oestrogen and manufactured ones from birth-control pills, and some industrial chemicals, pesticides and compounds in household items are endocrine disruptors, which mimic hormones. The waste water is filtered and processed, but many contaminants remain and settle into ocean sediment, where they are consumed by bottom-feeding organisms. Excessive amounts of real oestrogens or oestrogen mimics can create "intersex" animals with male and female genitals. Previously, scientists have shown that some fish with the altered organs were infertile. The mixed-s fish were found among two common species of flatfish that feed in bottom sediments: English sole and hornyhead turbot. Eighty-two male turbot and sole were caught, and the 11 with male and female organs were found at eight of 14 sites, said Doris Vidal, a researcher at the institute, who led the study.
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