New BPA and BPS health concerns
A new study, published in the Proceedings of the National Academy of Sciences, has found that exposure to bisphenol A (BPA) and one of its substitutes can affect nerve growth in the brain, and have an associated effect on behaviour.
The research, carried out on zebrafish, found that embryonic zebrafish treated with a low dose of BPA led to a 180% increase in nerve growth within the hypothalamus – the part of the brain implicated in aggression and hyperactivity. Exposure to the same dose of bisphenol S (BPS) – a related chemical used as a substitute in some BPA-free products – resulted in a 240% increase in nerve growth in that area of the brain.
What is BPA?
BPA is a chemical that has been used in various plastics for over 50 years. It can leach into our food from the epoxy resin coatings used to line most food and drink cans, as well as from polycarbonate plastic tableware, food storage containers, drink bottles and baby bottles.
Concerns about BPA and its potential impact on human health were initially raised after evidence from animal feeding studies suggested that long-term exposure to BPA can disrupt the endocrine system because the chemical mimics hormones that regulate body functions.
Experts respond to the study
"Extra caution needs to be taken"
Dr Anna Callan, lecturer in the School of Medical Sciences at Edith Cowan University said the fact that the effects in this study were seen at low doses of BPA exposure (matching the concentrations of BPA seen in a local river) is important, as many endocrine disrupting chemicals don't follow linear dose response curves (i.e. effects seen at low concentrations may differ from those seen at higher concentrations). "This means that extra caution needs to be taken by regulatory authorities when they determine the tolerable level of exposure for chemicals such as Bisphenol A," she said.
"Not a cause for alarm"
But Dr Ian Musgrave, senior lecturer in Pharmacology at the University of Adelaide, said the study isn't applicable to human environmental exposures.
"The concentrations of BPA, while low, are still much higher than humans would be exposed to. The concentrations of BPA the zebrafish embryos were exposed to that resulted in hyperactivity were roughly 1000 times higher than found in the blood of children with high exposure to BPA. Furthermore, the zebrafish embryos were directly exposed to the BPA at times when the major degradation pathway of BPA has not yet developed," he said.
According to Musgrave, human embryos at a similar developmental stage are protected by the placental barrier and the mother's enzymes that remove BPA from the circulation. "Human embryos would never be exposed to the kinds of BPA levels in this experiment. While a very interesting paper, it is not cause for alarm," he said.
"Study will increase pressure on manufacturers to seek alternatives to BPA"
Professor Ian Rae, honorary professorial Fellow at the University of Melbourne and former president of the Royal Australian Chemical Institute believes the results of the study will increase pressure on manufacturers to seek alternatives to BPA. "The molecules of BPA and BPS are similar in shape and polarity and so likely to bind to the same receptor and, unsurprisingly, produce similar effects. So while BPS seems to be the alternative of the day, its effects have not been widely investigated and it could come under pressure, too," he said.
What's Australia doing about BPA?
In 2010, in response to consumer concerns about BPA, the Australian government announced a voluntary phase-out by retailers of polycarbonate plastic baby bottles containing BPA. About the same time Australian Food and Grocery Council members also began voluntarily phasing out the use of BPA in polycarbonate plastic baby bottles, and many companies now have BPA-free options available.
Also in 2010:
- The ACCC conducted tests and found no detectable amounts of BPA migrate from typical infant feeding bottles, infant sip cups and two leading brands of infant formula supplied in Australia.
- FSANZ analysed levels of BPA migrating from foods packaged in polycarbonate plastics, steel cans with epoxy lining and some glass jars with metal lids and found that only a small number of samples had levels of BPA and there was no detectable BPA in infant formula prepared in several typical infant feeding bottles.
How can I avoid BPA?
If you're concerned about exposure to BPA – or its replacement – choose products in containers made from glass, rather than plastics or metals where possible.
Food safety authorities on BPA
In November 2014 the US Food and Drug Administration (FDA) announced the results of its review of more than 300 studies relating to BPA and its reported effects. It stated that it considered BPA to be safe at the current levels occurring in foods.
In January 2014, the European Food Safety Authority proposed to reduce the Tolerable Daily Intake for BPA following an exposure assessment and review of toxicological studies on its safety, but said current exposure for all age groups would still be well below the proposed new TDI.