Bisphenol A (BPA) has been used for decades in a wide variety of consumer products, like metal food and beverage containers, thermal paper store receipts, and dental composites.

Though the FDA has found BPA safe after numerous studies, because it can exhibit hormone-like properties the public has grown concerned about conflicting claims. There have been studies that have found exposure of rodent fetuses, infants, children or adults can cause cause abnormalities, including cancer, as well as reproductive, immune and brain-behavior problems. 

Researchers at the University of Missouri are now saying that daily exposure to very low concentrations of BPA by pregnant females can cause fetal abnormalities in primates.

"BPA is an endocrine disrupting chemical that has been demonstrated to alter signaling mechanisms involving estrogen, androgen and thyroid hormones," said Frederick vom Saal, Curators Professor of Biological Sciences. "Previous studies in rodents have demonstrated that maternal exposure to very low doses of BPA can significantly alter fetal development, resulting in a variety of adverse outcomes in the fetus. Our study is one of the first to show this also happens in primates."

Most studies involving BPA have been conducted on laboratory mice and rats and weren't methodologically valid, leading U.S. regulatory agencies to call for studies in primates. With funding provided by the National Institute of Environmental Health Sciences (NIEHS), vom Saal and colleagues studied the chemical's blood levels in pregnant female rhesus monkeys and their fetuses, which are more similar to human fetuses than rats are.

Frederick vom Saal and colleagues say that BPA can cause fetal and hormonal imbalances in primates. Credit: University of Missouri News Bureau

After collecting tissue samples, other researchers analyzed the tissues to determine if dBPA exposure was harmful to fetal development. Researchers found evidence of significant adverse effects in mammary glands, ovaries, brain, uterus, lung and heart tissues in BPA exposed fetus when compared to fetuses not exposed to BPA. The abnormalities were caused by levels of BPA in the monkey fetuses that were very similar to levels reported in previous studies of BPA in human fetuses.

"The very low-level exposure to BPA we delivered once a day to the rhesus monkeys is far less than the BPA levels humans are exposed to each day, which reflects multiple exposures," vom Saal said. "Our findings suggest that traditional toxicological studies likely underestimate actual human exposure and show, unequivocally, that biologically active BPA passes from the mother to the fetus. Additionally, our latest study shows that BPA causes damage to developing systems of monkey fetuses, and this is of great concern for human fetuses."

Citation: Frederick S. vom Saal, Catherine A. VandeVoort, Julia A. Taylor, Wade V. Welshons, Pierre-Louis Toutain, Patricia A. Hunt, 'Bisphenol A (BPA) pharmacokinetics with daily oral bolus or continuous exposure via silastic capsules in pregnant rhesus monkeys: Relevance for human exposures', Reproductive Toxicology, 25 February 2014, DOI: 10.1016/j.reprotox.2014.01.007. Source: University of Missouri-Columbia