Humans are probably being exposed to far more of a widely used dangerous chemical – found in plastics, canned goods and receipt paper – than previously understood, according to a new study.
The analysis, in the peer-reviewed scientific journal the Lancet, uses a new method for evaluating exposure to BPA, or bisphenol-A.
BPA disrupts hormones critical to many body functions and is linked with obesity and other diseases. Pregnant women who are exposed to it are more likely to have children who have problems with growth, behavior and fertility, as well as a higher cancer risk. Many companies have phased out using BPAs, marketing new products with similar replacement bisphenols as safer without sufficient evidence for their claims, experts say.
The new research examined levels of BPA in urine but also counted the metabolites of BPA. Metabolites are formed when the body breaks down and eliminates a chemical.
Using the new method, the scientists analyzed the urine of 29 pregnant women in their second trimester and found their BPA exposure levels to be an average of 44 times higher than what was measured with the traditional method.
Patricia Hunt, a co-author of the study who is a molecular biosciences professor at Washington State University, said she was “horrified” by the high levels her group found in the pregnant women.
“The regulatory decisions for this chemical, BPA, have been based in part on the idea that our exposure is so very, very low,” Hunt said. “And I just don’t think that’s true. Our data really challenged that assumption.”
Hunt argues that in the US, the new method should be used to re-evaluate samples collected and studied by the Centers for Disease Control as part of its National Health and Nutrition Examination Survey (NHANES). That survey is used to understand chemical exposures to Americans.
She said incorporating the metabolites into studies of exposure may explain why levels of BPA in humans appeared to be very low, despite an increase of production of the chemical.
BPA metabolizes rapidly when it is ingested, making it harder to study. It can linger longer when exposure is through the skin.
Many chemicals are analyzed without consideration of their metabolites, which may not be giving regulators a full understanding of the human health impacts, Hunt said.