Even low-level BPA exposure is too much, expert says: primate foetuses affected

Daily exposure to Bisphenol A (BPA), even at very low concentrations, has recently been shown to cause foetal abnormalities in primates, raising questions about its effects on human foetuses.

“BPA is an endocrine-disrupting chemical that has been demonstrated to alter signalling mechanisms involving oestrogen, androgen and thyroid hormones,” said Frederick vom Saal, Curators Professor of Biological Sciences in the College of Arts and Science at the University of Missouri.

“Previous studies in rodents have demonstrated that maternal exposure to very low doses of BPA can significantly alter foetal development, resulting in a variety of adverse outcomes in the foetus. Our study is one of the first to show this also happens in primates.”

Although the use of BPA has been phased out in some products in the EU and Canada, thus far the Australian Government has only suggested a voluntary phase-out of BPA in polycarbonate baby bottles.

A Food Standards Australia New Zealand (FSANZ) statement on BPA says, “The overwhelming weight of scientific opinion is that there is no health or safety issue at the levels people are exposed to.” Professor vom Saal’s research may challenge this attitude.

With funding provided by the National Institute of Environmental Health Sciences (NIEHS), vom Saal and colleagues studied BPA levels in pregnant female rhesus monkeys and their foetuses, which are considered to be very similar to human foetuses.

After collecting tissue samples, other researchers analysed the tissues to determine if BPA exposure was harmful to foetal development. Researchers found evidence of significant adverse effects in mammary glands, ovaries, brains, uterus, lungs and heart tissues in BPA-exposed foetuses when compared to foetuses not exposed to BPA. The abnormalities were caused by levels of BPA in the monkey foetuses that were very similar to levels reported in previous studies of BPA in human foetuses.

“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 foetus. Additionally, our latest study shows that BPA causes damage to developing systems of monkey foetuses, and this is of great concern for human foetuses.”

The study, ‘Bisphenol A (BPA) pharmacokinetics with daily oral bolus or continuous exposure via silastic capsules in pregnant rhesus monkeys: relevance for human exposures’, was published in the journal Reproductive Toxicology.