The gender benders: are environmental 'hormones' emasculating wildlife? - includes related articles

Science News, Jan 8, 1994 by Janet Raloff

Apopka's animals also possessed feminized 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 8 years old -- from each of five lakes. Apopka's gators again distinguished themselves. The phallus on males was one-half to one-third the normal 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 dicifol -- 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 occurred 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 feminizaton. To test that link, his team this summer painted gator eggs from Lake Woodruff with concentrations of DDE and dicofol to produce tissue contamination typical of hatchings from Lake Apopka.

Through not all their tests have been completed yet, Guillette told SCIENCE NEWS that "we're finding hormone levels in these hatchings that are almost identical to those in Apopka hatchings." He adds, "That's about the closest thing to proof science is ever likely to give."

In the meantime, Apopka's gators continue to suffer. Since a catastrophic much more potent" than estradiol, Sumpter's team says. Indeed, they conclude, EE represents one of "the most potent of biologically active molecules."

If present in potable waters, however, EE must occur in concentrations below the limits of detection, the British team found. In fact, Sumpter notes, it was only after their research was completed that his team learned of another possible candidate: nonylphenols (SN: 7/3/93, p.12).

These are breakdown products of alkylphenol polyethoxylates (APEs), a class of surfactants first marketed in the 1940s. Today,APEs are used in detergents (including many U.S. dishwashing liquids), pesticides, herbicides, toiletries, and products that need to wet surfaces. Through the parent APEs are not estrogenic, Summer describes the nonylphenols as "directly estrogenic" -- which means that they can bind to an activate the body's estrogen receptor.

Though nonylphenols occur in concentrations of more than 1 milligram per liter of water in poor-quality English rivers -- especially downstream of textile mills -- concentrations if 1 to 50 micrograms per liter [micro]g/1) are more typical of waters in England and Europe, Sumpter says. U.S. concentrations, by contrasts, tend to fall below 1 [micro]g/1.