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vestigial oviducts on the right side. Many males also bore feminine characteristics, such as oviducts, recalls avian toxicolo- gist D. Michael Fry of the University of California, Davis. Moreover, he notes, the males' left gonad "had tissues that were both ovarian and testicular-so it was an intersex, or hybrid, gonad" To connect these effects with estro- genic pollutants, Fry and his colleagues conducted a number of experiments dur- ing the 1980s. In one, they injected eggs of contaminant-free gulls with estradiol or with an estrogenic pesticide such as DDT. When the hatchlings emerged, they ex- hibited the same array of feminized sex organs as DDT-contaminated Western gulls on Santa Barbara Island, off the coast of California. In effect, DDT "chemically castrated" the males, Fry says. He suspects the males' likely lack of interest in mating explains not only why female gulls domi- nated Santa Barbara Island's breeding colony in the late 1960s and early 1970s, but also why the females cohabited. More recently, Fry has turned his atten- tion to the effects of other estrogenic pesticides and PCBs. This summer he began studying common terns, a relative of the gull. Fry studied male embryos from nests along New Bedford Harbor, Mass., located near a toxic waste site contaminated with PCBs. Only four of the 15 males that he analyzed appeared nor- mal. The rest exhibited varying degrees of feminized sex organs. All never set out to do any toxicology," maintains Louis J. Guillette Jr., a reproductive endocrinologist at the University of Florida in Gainesville. But the team he heads has recently distinguished itself as one of the foremost in environmental-hormone toxicology. It all began six years ago, when the state of Florida asked him to find out what makes a good alligator egg. Alligator ranching has become a multi- million-dollar industry in Florida, and ranchers wanted to know how many eggs they could harvest from the wild without jeopardizing the survival of this once- endangered species. So Guillette's team began surveying the hatching rate of eggs on various lakes: in all, more than 1,200 nests accounting for more than 50,000 alligator eggs. It didn't take long, Guillette says, "be- fore we realized there was something fundamentally different about one lake." It was Apopka, Florida's fourth largest freshwater body. Whereas 70 to 80 percent of the eggs in most alligator nests hatched, between 80 and 95 percent of those from Apopka failed to hatch. Moreover, of the alligators that did hatch at Apopka, roughly half died within two weeks - a mortality rate at least 10 times that expected for such neonates. As one measure of the health of these animals, Guillette's team began two years ago to examine the fluid that leaks out of eggs at the time of hatching and to analyze it for estrogen and testosterone. In females, estrogen should predominate, whereas males should have more tes- tosterone. Eggs from Lake Woodruff - with normal hatching rates - displayed those classic patterns. Apopka eggs didn't. One group showed what at first appeared to be the normal female pattern. Another group appeared to be "superfemales," with ratios of estro- gen to testosterone twice as high as normal. "We didn't have any group that looked like males," Guillette recalls. It turns out that there were indeed males - the gators emerging from eggs exhibiting the standard female ratio of hormones. But the concentrations of the hormones contributing to that ratio were not normal. "These animals were making almost no testosterone and almost no estrogen," Guillette explains. Six months later, the researchers re- turned to Lakes Woodruff and Apopka to measure hormones in the young. "We found exactly the same condition that we had seen in the eggs," he says - "females with about twice the estrogen typical of a female and almost no testosterone in the males" Apopka's animals also possessed femi- nized internal reproductive organs. The males bore what looked like ovaries, for example, while follicles in the females possessed not only abnormal eggs, but also far too many eggs. Last summer, Guillette's team collected more than 100 juvenile alligators - animals 2 to 8years old-from each of five lakes. Apopka's gators again distin- guished themselves. The phallus on males was one-half to one-third the nor- mal size, and the females' ovaries "looked burned out," Guillette says. Moreover, estrogen and testosterone production in all Apopka gators was minimal - as if, Guillette says, the ovaries and testes were indeed burned out. What accounts for Apopka's feminized alligators? The culprit is estrogenic pesticides, Guillette testified at an Oct. 21 hearing before the House Subcommittee on Health and the Environment. Tower Chemical Co. for years made the pesticide dicofol - a molecule that he says looks like DDT with an extra oxygen atom. Production methods at the plant, situated on the shore of Lake Apopka, weren't always ideal, Guillette says. Spills oc- curred and much of the dicofol was laced with up to 15 percent DDT or DDE. Tower's defunct plant is now a toxic waste site. While high concentrations of DDT have been measured in Apopka gators, Guillette cautions that this doesn't prove DDT is responsible for the observed feminization. To test that link, his team this summer painted gator eggs from Lake Woodruff with concentrations of DDE and dicofol to produce tissue con- tamination typical of hatchlings from Lake Apopka. Though not all their tests have been completed yet, Guillette told SCIENCE NEWS that "we're finding hormone levels in these hatchlings that are almost identi- cal to those in Apopka hatchlings" He adds, "That's about the closest thing to proof science is ever likely to give" In the meantime, Apopka's gators con- tinue to suffer. Since a catastrophic 0 c? w JANUARY 8, 1994 25 Florida panthers: Researchers are investigating whether environmental hormones might help explain their testicular problems, puzzling sex- hormone concentrations, and falling fertility.