Rochester study raises new questions about controversial plastics chemical

29-Jan-2009 - USA

A University of Rochester Medical Center study challenges common assumptions about the chemical bisphenol A (BPA), by showing that in some people, surprisingly high levels remain in the body even after fasting for as long as 24 hours. The finding suggests that BPA exposure may come from non-food sources, or that BPA is not rapidly metabolized, or both.

Controversy around BPA is mounting. In December the U.S. Food and Drug Administration agreed to reconsider the health risks of the chemical, which is used to make plastic baby bottles, water bottles and many other consumer products. Scientific studies suggest that BPA may harm the brain and prostate glands in developing fetuses and infants; adults with higher BPA levels in their urine were linked to higher risks for heart disease and diabetes, according to a study published last September in the Journal of the American Medical Association .

The latest finding from Rochester is important because, until now, scientists believed that BPA was excreted quickly and that people were exposed to BPA primarily through food. Indeed, the FDA and the European Food Safety Authority have declared BPA safe based, in part, on those assumptions.

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"Our results simply do not fit that picture," said lead author Richard W. Stahlhut, M.D., M.P.H., of the University of Rochester's Environmental Health Sciences Center. "The research community has clues that could help explain some of these results but to date the importance of the clues have been underestimated. We must chase them much more vigorously now."

Stahlhut and colleagues obtained data for a sample of 1,469 American adults through the Center for Disease Control's National Health and Nutrition Examination Survey (NHANES). The researchers sought to explore the link between BPA urine concentration and the length of time a person had been fasting.

Accepting the widely held assumption that food is the most common route of exposure to BPA, Stahlhut expected to see a relationship between the last food ingested, fasting time, and BPA levels. People who had fasted longest (15 to 24 hours), for example, should have had much lower BPA levels than people who had eaten more recently, Stahlhut said.

Instead, those who fasted had levels that were only moderately lower than people who had just eaten. This is significant because scientists expected BPA levels to decrease by about half, every five hours. "In our data, BPA levels appear to drop about eight times more slowly than expected – so slowly, in fact, that race and sex together have as big an influence on BPA levels as fasting time," Stahlhut said.

Original publication: Environmental Health Perspectives 2009.

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