COLUMBIA — A new study by researchers at MU and other scientists at the University of California-Davis and Washington State University concluded that human exposure to bisphenol A, a toxic chemical found in many consumer products, is eight to 10 times higher than the EPA “safe” daily intake dose and poses a threat to human health.
A National Institutes of Health study in 2005 measured BPA. The research found people with high levels of the chemical would be much more likely to have a variety of health problems including heart disease, diabetes, obesity and cancer.
Julia Taylor, lead author and associate research professor at the MU, said many earlier estimates of human BPA exposure were in the range of less than 1 part per billion, although "one or two estimates were quite a bit higher."
The most recent research found human exposure to BPA is closer to 500 parts per billion, Taylor said. “It’s a huge difference. Our data support new estimates of human exposure proposed earlier this year.”
The new study discovered that women, female monkeys and female mice have major similarities when it comes to how BPA is metabolized.
“Our paper shows that as BPA is metabolized the levels of BPA in blood are very similar in mice, monkeys and humans,” Taylor said. “Since human and mice have the same blood level of BPA after exposure to the same amount of BPA, if that amount causes harm in mice, it could cause harm in humans.”
“This is particularly important because the amounts of BPA that harm health in lab studies on mice are lower than those which lead to the blood levels of BPA found in the average person,” Taylor said.
The study was published online in the Sept. 20 NIH journal, Environmental Health Perspectives. It was authored by researchers at the MU Division of Biological Sciences, Veterinary Medical Diagnostic Lab and the Department of Biomedical Sciences, in collaboration with scientists at the University of California-Davis and Washington State University.
BPA is one of the world's highest production-volume chemicals, with more than 8 billion pounds made per year. The chemical is in the plastic used to line food and beverage cans.
“We have traditionally thought that food and beverage containers which are made out of polycarbonate plastic is the major source of BPA exposure," said Sonya Lunder, senior analyst for the Environmental Working Group, non-profit organization in Washington, D.C. "And this includes baby bottles and sport drink bottles. However federal agencies have not thoroughly accounted for the variety of BPA uses.”
“In addition to food, we know that people have daily contact with BPA-treated paper, and that hospitalized infants receive lots of BPA—likely through PVC medical tubing.” Lunder said.
Other daily products contain BPA include some of the thermal paper used for sales receipts, CDs, dental sealants, some children’s toys, eyeglass lenses, and some epoxy adhesives.
Many scientists have urged Food and Drug Administration to ban the use of BPA. “We have sent comments and letters to FDA about the safety of BPA and our concern about baby safety,” Lunder said.
The FDA has refused to ban BPA, recommending additional studies instead. The agency decided there were uncertainties regarding interpretation of these studies and their potential implications for human health effects of BPA exposure. These uncertainties included: the relevance of some animal models to human health, differences in the metabolism of BPA at different ages and in different species, and limited or absent information for some studies.
The MU researchers work with Frederick vom Saal, curators' professor of biological sciences at MU and a leading authority on BPA and human health.
The researchers have renewed their request for stricter governmental regulation for BPA.
“Further evidence of human harm should not be required for regulatory action to reduce human exposure to BPA,” vom Saal said in prepared remarks announcing the latest research findings.