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much more potent" than estradiol, Sump- 1 ter'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 al- kylphenol polyethoxylates (APEs), a class of surfactants first marketed in the 1940s. Today, APES are used in detergents (including many U.S. dishwashing liq- uids), pesticides, herbicides, toiletries, and products that need to wet surfaces. Though the parent APES are not estro- genic, Sumpter describes the nonyl- phenols as "directly estrogenic" -which means that they can bind to and activate the body's estrogen receptor. Though nonylphenols occur in concen- trations of more than 1 milligram per liter of water in poor-quality English rivers - especially downstream of textile mills - concentrations of 1 to 50 micrograms per liter (Ng/1) are more typical of waters in England and Europe, Sumpter says. U.S. concentrations, by contrast, tend to fall below 1 µg/l. "Because of their ubiquitous presence in the aquatic environment and the `high' concentrations," Sumpter told SCIENCE NEWS, "we consider them a good candi- date to account for the estrogenic effects [found in the study with trout and carp]." Though only perhaps 1/10,000 as potent as EE, nonylphenols "are pretty resistant to degradation and [they] bioaccumulate, which will increase the likelihood of them producing physiological effects," he ar- gues. But nonylphenols are not the only products formed by the breakdown of APES. And because many of those others are not monitored, Sumpter says, "the total concentration of all the closely related degradation products remains unknown." Environmental estrogens are also suspected of playing a role in repro- ductive problems plaguing the Flor- ida panther, a species whose surviving members total only 30 to 50 animals. Between 1985 and 1990, 67 percent of male Florida panthers were born with one or more undescended testes, a condi- tion known as cryptorchidism. Just 10 years earlier, only 14 percent of males were cryptorchid, observes Charles Face- mire, an ecological geneticist with the U.S. Fish and Wildlife Service in Atlanta. In addition, he notes, at least one non- cryptorchid male is sterile, and even some of the apparently normal males produce abnormal or deformed sperm. Initially, these problems were assumed to trace to a loss of genetic diversity in the heavily inbred species (SN: 9/25/93, p.200), Facemire says. But a few months ago, he and Mike Dunbar, a veterinarian with the Florida Game and Fresh Water Fish Commission in Gainesville, decided to investigate whether estrogenic con- taminants might also be contributing to these reproductive problems. Their initial blood sampling program turned up males with unusual steroid hormone ratios. For instance, one male had nearly twice as much estrogen as testosterone. (This animal should have had two to three times as much tes- tosterone as estrogen.) At least two other males had similarly skewed ratios; both of them were also cryptorchid. Equally perplexing, at least one female had more testosterone than estrogen. "We don't know enough about the spe- cies to know if these hormone levels might be normal under certain circum- stances. But we don't think they are," Facemire says. Though genetic problems cannot be ruled out, he acknowledges, "I suspect we're going to find that the problems are due more to estrogenic chemicals in the environment" Working under that assumption, Face- mire's office has just issued a prohibition on the use of estrogenic chemicals - principally pesticides - in the 100 or so federally managed wildlife refuges in the southeastern United States. At the same time, Facemire's office has initiated four other investigations into possible effects of environmental hormones on wildlife- including one involving the prothonotary warbler in Alabama and another involv- ing sea turtles in Georgia. Nor are these the only animal studies linking reproductive changes with expo- sures to hormone-mimicking contami- nants. Laboratory studies on fish at the University of Guelph in Ontario, for in- stance, have shown that white suckers exposed to papermill effluent-often rich in dioxins and related compounds-took longer to mature, developed smaller go- nads, experienced reduced fertility, and had lower than normal concentrations of steroid hormones in their blood. More- over, Glen Van Der Kraak and his co- workers reported at an international meeting on the topic in September 1990, male fish exposed to papermill wastes developed reduced secondary sex char- acteristics. Other researchers have begun linking reproductive problems in salmon to rela- tively high concentrations of hormone- like contaminants. And at a conference sponsored by the U.S. and Canadian governments three years ago, PCBs in such fish were linked to dramatic de- clines in the reproduction of minks and otters around the Great Lakes. Finally, University of Wisconsin scien- tists demonstrated two years ago that low prenatal exposures to dioxin feminized the behavior of male rats during adulthood - and sharply reduced their production of sperm. Indeed, the re- searchers concluded, the developing male reproductive system appears to be more sensitive to the effects of this hor- mone-like toxicant that any other organ or organ-system studied (SN: 5/30/92, p.359). \\ ecause we're only just getting g to the basics in this field," Pal- mer says, even simple ques- tions about the reproductive effects of environmental hormones for most spe- cies must go unanswered. But he sus- pects that biologists are going to have to move fast in finding those answers if some contaminated populations are to survive. Toxic-pollutant concentrations in the environment have dropped to where they can seldom kill most adult animals out- right, he says. However, in some species, he fears, "We. may have gotten to a point where the adults look healthy but are so reproductively impaired that that popu- lation may already be extinct-and we're just waiting for the last remaining adults to die [of old age]." ? Jan. 22: Environmental hormones and men BINDERS KEEPERS Bind and save • your copies of ME Science News! ! ! Nf% Keep your copies of SCIENCE NEWS always available for quick, easy reference in this attrac- • • tive, practical binder. Simply snap the magazine in or out in a few seconds - no punching or mutilating. It opens flat-for easy reference and readability. Sturdily constructed, this blue vinyl binder stamped in a gold tone will make a fine addition to your library. SCIENCE NEWS binders hold one six-month volume of SCIENCE NEWS. Each of the 26 issues snaps into the cover with a metal rod. $8.00 each, 2 for $15.00. Postage- paid. Order now, from Science News 1719 N Street, NW. Washington, D.C. 20036 Domestic orders only JANUARY 8, 1994 27