The new SCOPE-IUPAC report says endocrine disruption can be expected in all animalsin which hormones initiate physical changes, including humans.
While human effects have not been proven or quantified, the European Commission has adopted a precautionary approach based on current knowledge on the possible effects of endocrine disruption in humans. Women, they say, may experience a greater risk for breast and ovarian cancer, and the female birthrate may decline. Possible male health impacts include lower sperm counts, smaller penis size, and increased risk for testicular cancer, according to the inter-governmental body representing 15 member states.
Peter Matthiessen, head of environmental chemistry and pollution at the U.K.'s Centre for Ecology and Hydrology says a major challenge facing scientists who study the impact of endocrine active substances is that the larger the animal, the harder it is to prove the effects of EASs.
"We've got much better data towards the lower end of the animal scale than the upper end," he said. "To be sure you know what's happening, you've really got to do an experiment in the lab to replicate the effect. You can do that with a shrimp or a fish, but not with a whale."
An added challenge for researchers studying endocrine disruptors is the likelihood that the substances act together in complex cocktails. This makes work to determine precise cause and effect even more difficult.
Mattiessen is co-author of a recent U.K. study that backs the finding of the SCOPE-IUPAC report. The study, recently published in the scientific journal Environmental Toxicology and Chemistry, suggests that the gender-bending impacts of EASs can be reversed.
During a five-year study, Matthiessen and his colleagues conducted a series of annual surveys of fish along the British coast to gauge trends in levels of feminization. The study was spurred by previous observations of feminization in estuarine fish, particularly the flounder, a common flatfish, Matthiessen said.
"We've known for some time that this fish has become feminized in estuaries where lots of people live and lots of sewage is going into the water."
Matthiessen said that the fish's changes were a reaction to estrogens present in human waste. Such estrogens derive largely from birth control pills and hormone-therapy drugs.
"What's really interesting is that in the Tyne [River] estuary in northeast England a really strong recovery kicked in," Matthiessen said, noting the phenomenon coincided with the upgrading of a major sewage treatment works. "Until then, most of the fish were very strongly feminized. For example, yolk was present in male blood plasma, which is highly abnormal. Then [after the sewage plant upgrade] there was this sudden drop in yolk protein concentrations which was sustained in subsequent years."
Matthiessen says modern sewage treatments, which are better at stripping out hormones, can help to tackle the problem of estrogen pollution.
The SCOPE-IUPAC report also calls for more detailed scientific analysis of endocrine disruptors, particularly those that may pose a risk even at very low levels. The report also advocates improved environmental safeguards, such as routine testing of chemicals for endocrine-disrupting properties.
The report also says substantial international coordination and cooperation on the issue is lacking at present and that the Intergovernmental Forum on Chemical Safety (IFCS), based in Geneva, Switzerland, should initiate global management of endocrine disruptors.
The European Union has adopted a community strategy for addressing the problem, including the development and validation of test methods and a review of laws governing chemical use. But this still doesnt go far enough, environmental groups say.
Clifton Curtis, of the Washington, D.C.-based WWF, said: "We know that the global production of chemicals is increasing, and at the same time we have warning signals that a variety of troubling threats to wildlife and human health are becoming more prevalent. It is reckless to suggest there is no link between the two, and give chemicals the benefit of the doubt."
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