Gender Transformed: Endocrine Disruptors in the Environment. (original) (raw)

In the late 1970s, anglers in England began reporting that they were catching bizarre fish-rainbow trout that seemed to be partly male and partly female. Perplexed, a biologist from Brunei University named John Sumpter went out to investigate these reports of what the media called "sexually confused fish."l He discovered that the trout were males that had indeed developed female characters, and he found that the best places to find these gender-bending fish were near sewage plants, in the lagoons and pools just below the discharge outlets for treated waste. The obvious question occurred to him: could anything in the sewage effluent be affecting the masculinity of the fish? Sumpter, with the help of fellow Brunei University biologist Charles R. Tyler and researchers from the Ministry of Agriculture, Fisheries, and Food, found male fish that were producing elevated levels of vitellogenin, a protein responsible for making egg yolks in female fish. Male fish possess a gene that can produce vitellogenin when triggered by estrogen, but ordinarily males lack enough estrogen-a female sex hormone--to trigger this gene. To test whether sewage treatment plants had anything to do with the elevated levels of vitellogenin in the male fish blood, the scientists took healthy male trout raised in captivity, put them in cages, and placed them for three weeks near the discharge points of thirty different sewage treatment plants. Soon those males began producing vitellogenin, just like females. 2