ROCHESTER, NY — Scientists at the University of Rochester Medical Center have found that in some people, surprisingly high levels of the chemical bisphenol A (BPA) remain in the body, even after people have fasted for as long as 24 hours, according to a January 28 university press release.

The study, which was published online on January 28 by the journal Environmental Health Perspectives, suggests that BPA exposure may come from non-food sources or that the chemical is not rapidly metabolized.

BPA is a chemical ingredient used in the manufacture of polycarbonate water bottles and other food packaging. BPA also is used in the manufacture of PVC water pipes.

In December, the US Food and Drug Administration agreed to continue to review the use of BPA in food contact applications, while maintaining the position that the chemical is safe. That decision followed a finding in October by a panel of FDA scientific advisors that FDA’s draft safety assessment of the chemical in food contact applications was inadequate. The panel’s finding was a response to an EPA statement in August that the public was not at risk from BPA, as WaterTech Online® reported.

Until now, scientists believed that BPA was excreted quickly and that people were exposed to BPA primarily through food. “Our results simply do not fit that picture,” lead author Richard W. Stahlhut, M.D., M.P.H., of the University of Rochester’s Environmental Health Sciences Center said in the release. “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 said he 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.

According to the authors, two possible explanations may exist for the higher-than-expected levels of BPA in people who fasted. One is that exposure to BPA might come through other means, such as house dust or tap water.

In addition, Stahlhut theorizes that BPA may seep into fat tissues, where it would be released more slowly. However, further study is needed to evaluate the effects of BPA on adipose tissue hormones and function, Stahlhut said, as well as more studies to compare BPA levels in fat versus blood and urine.

The Centers for Disease Control estimates that 93 percent of Americans have detectable levels of BPA in their urine.

Janet Nudelman, director of program and policy at health advocacy group Breast Cancer Fund, was quoted as saying in a Milwaukee Journal Sentinel article about the study published in the Detroit Free Press, “The study reinforces the urgent need for stricter government oversight and regulation of this extremely toxic chemical. It adds to what we already know about BPA, a chemical so powerful that at extremely low levels — parts per billion or even parts per trillion — it can cross the placenta and alter the mammary gland of the developing fetus, increasing breast cancer risk later in life.”

To read the full University of Rochester press release, click here.

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