Hormone mimics: New assessments air.
Nonylphenols taint waterways throughout the world, especially those downstream of municipal waste treatment plants.
Given half a chance, however, waterborne nonylphenols will take to the air, a new study finds. Their evaporation from water allows the chemicals to travel long distances before settling down again--potentially on land far from water, notes study leader Steven J. Eisenreich of Rutgers University in New Brunswick, N.J.
Using a chemical fingerprinting technique known as gas chromatography, his team identified pollutants in water in the Hudson River estuary and in air nearby. Their work, reported in the Aug. 1 ENVIRONMENTAL SCIENCE & TECHNOLOGY, turned up both water and air pollutants with "an unequivocal match" to the signature of nonylphenols.
The data, the first showing these pollutants in the atmosphere, detected airborne amounts ranging from just above zero to 70 nanograms per cubic meter, which the researchers regarded as a "high concentration." Eisenreich says, "Water was definitely the source of these chemicals in the air."
The Rutgers chemists suspect airborne nonylphenols are "ubiquitous" worldwide. Because nonylphenol concentrations in some European rivers are 10 to 100 times as high as in the Hudson estuary, the airborne chemicals are perhaps even more prevalent elsewhere in the world than in the area studied. The air data raise concern about new routes of human exposure, the scientists say.
Their finding disturbs Susan Sang of the World Wildlife Fund Canada in Toronto, which advocates a phaseout of surfactants that degrade to nonylphenols. When nonylphenol concentrations in water diminish, it has looked like the pollutants were breaking down, Sang says. "It now appears they were just evaporating and moving to where you wouldn't have expected to find them," she says.
Fish exposed to nonylphenols have developed reproductive and other abnormalities (SN: 5/8/99, p. 293). Because of such findings, Sang notes, Canadian officials have recommended that pregnant women avoid nonylphenol exposure.
The Canadian government is also assessing nonylphenol risks. If its findings, due next spring, indicate the pollutants are toxic, the government could require monitoring or even limit nonylphenol release, notes Philippa Cureton of Environment Canada in Hull, Quebec.
Determining whether such pollutants pose risks to people, however, will generally require much more research, concludes a panel convened by the National Research Council (NRC) in Washington, D.C. It released a report of its 4-year assessment of the toxicity of hormonelike chemicals last week.
"We couldn't find any clear evidence that people had been harmed by typical environmental exposures to hormonally active chemicals," observes panel member James C. Lamb IV, a consulting toxicologist in Reston, Va.
Then again, few studies have probed for effects in humans, argues panelist Ana M. Soto of the Tufts University School of Medicine in Boston. A further limitation of the new assessment, she maintains, was its "focus on correlations between one chemical and an effect." Most people face coincident exposures to several hormone mimics--such as nonylphenols, phthalates, and PCBs--and her own studies indicate that the effects can be "at least additive," she says.
When it comes to wildlife, "there was clearly evidence of very negative reproductive effects in populations exposed to chemicals commonly called endocrine disruptors," notes panelist Joanna Burger from Rutgers. The NRC consensus report "doesn't dismiss these findings," she says. Indeed, she notes, it documents many of the hormonal mechanisms that are likely responsible.
Though many pollutants may exhibit hormonal activity, few studies have proved that such hormonal action is responsible for the toxicity of these agents, says panel chair Ernst Knobil from the University of Texas Medical School at Houston. He says that one of his committee's "most radical" actions was to "abandon the term endocrine disruptor" to describe hormone mimics.
To Lamb, this decision indirectly challenges the value of a new federal program to screen all commercial U.S. chemicals for hormonal action (SN: 10/17/98, p. 251). He says, "I'm concerned that we'll spend all this money chasing hormones--with no certainty that it will help us predict risks."
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|Article Type:||Brief Article|
|Date:||Aug 14, 1999|
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