A national study that tested samples of human hair for mercury suggests that as many as one in every seven women of childbearing age in Texas has been exposed to potentially dangerous levels of the substance.
A national study that tested samples of human hair for mercury suggests that as many as one in every seven women of childbearing age in Texas has been exposed to potentially dangerous levels of the substance, its author said. The ongoing study, touted as the largest of its kind, also found a link between levels of the neurotoxin and the amount of seafood a person eats. "This confirms what we've already known, but this shows how strong the relationship is," said Steven Patch, a professor of statistics at the University of North Carolina at Asheville's Environmental Quality Institute. Texas fared better than the nation as a whole, where more than one in every five women of childbearing age -- 16-49 -- tested for mercury above the Environmental Protection Agency's recommended health level. The study examined 6,583 people in all 50 states, but the EPA sets its standards based on pregnant women because mercury is thought to be especially dangerous to developing fetuses. Babies and small children are also considered at high risk.
Patch said the level of mercury in hair could be correlated to the amount in the body. A reading of about one part per million in the hair is the equivalent to the EPA's recommended limit, he said.
The study found that someone who eats eight servings or more of fish a month was likely to reach that limit.
Mercury is found naturally in the environment, and also produced by humans -- most often by coal-fired power plants. Fish absorb the toxin or accumulate it from eating other fish or plants that contain mercury.
The biggest fish tend to contain the most mercury. These include king mackerel, grouper, shark and swordfish.
Patch's study found higher levels of exposure than the National Health and Nutrition Examination Survey, conducted by the federal Centers for Disease Control and Prevention in 1999 and 2000.
That study found slightly more than one in 10 women of childbearing age with elevated levels of mercury.
Keller Thormahlen, senior toxicologist with the Texas Department of State Health Services, said Patch's results are probably skewed because he relied on volunteers.
"When it's self-selected, that's a big bias," he said.
Patch acknowledged the problem and even discussed it in the study. But he said that using volunteers was the most cost-effective way of doing such a large research project.
Greenpeace, the Sierra Club and other environmental groups recruited participants. The volunteers had to fill out a survey and pay $25 for the testing.
"It is a self-selected survey and it appears that our participants consume more fish than the average," Patch said.
Anyone interested in being part of the study can find more information at www.greenpeaceusa.org/mercury.
Environmental groups in Texas are touting the report as further proof that the state needs to require stringent mercury controls at coal-fired power plants. After a 15-year hiatus, power companies have proposed seven new coal plants in Texas.
These include a new plant proposed by San Antonio's CPS Energy that state environmental regulators recently approved. After long and contentious negotiations with environmental groups, CPS Energy agreed to a strict set of mercury and other pollution controls.
Neil Carman of the Sierra Club's Lone Star Chapter said the company set a good precedent.
"CPS should be commended for what they did, even though it took a lot of public pressure," he said. "I don't know of any other utility in Texas that has stepped up to the plate like that."
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Source: Knight Ridder/Tribune Business News