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.
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.
The latest data also supports the idea that individuals might be re-exposed throughout the course of a day, Stahlhut said. In 2000 another research group found that BPA can migrate from PVC pipes or hoses into room temperature water, producing another potential route of ex
|Contact: Leslie Orr|
University of Rochester Medical Center