Research from a team of US scientists is again raising doubts over the safety of “BPA-free” plastic products. The animal studies described in a new article suggest bisphenol S (BPS) “causes almost identical changes in gene expression” compared to bisphenol A (BPA). The conclusion is BPS should be considered as hazardous to human health as BPA, however, there is still debate over exactly how dangerous these chemicals actually are.
Bisphenol A (BPA) is an industrial chemical used in the production of plastic products and resins. To this very day the chemical is used in a vast array of different products, however, in the late 1990s scientific studies began appearing questioning the the safety of BPA.
A large volume of animal research quickly accumulated, suggesting BPA causes endocrine dysfunction, metabolic disease, and possibly even cancer. Over the past decade in particular, BPA has been the central focus of many public health debates, and although there is still disagreement from different global health bodies over the human health effects of BPA exposure, the growth of BPA-free products suggests the general public simply doesn’t want to risk it.
BPA-free plastic products use a variety of alternative chemicals to generate the same results as BPA. Some of these substitutes are unknown, but many companies have simply replaced BPA with chemically similar bisphenol compounds such as BPS or BPF.
So a BPA-free label may be true but is BPS a safer replacement? A growing body of research is suggesting it probably isn’t.
This new study compared the effects of both BPA and BPS on a developing mouse placenta.
"Synthetic chemicals like BPS can penetrate through the maternal placenta, so whatever is circulating in the mother's blood can easily be transferred to the developing child," says Cheryl Rosenfeld, a University of Missouri researcher working on the new study. "This mouse model is the best model we have now to simulate the possible effects of BPS during human pregnancy, because the placenta has a similar structure in both mice and humans."
The results strikingly revealed BPA and BPS conferred nearly identical effects on the animal’s placenta. The two chemicals altered expression of the same 13 genes and reduced placental serotonin concentrations. Rosenfeld suggests these chemical disruptions to placental serotinin production can fundamentally alter fetal brain development.
“Lower levels of serotonin can compromise fetal brain development because during this critical time in development the brain relies on the placenta to produce serotonin,” explains Rosenfeld. “Thus, developmental exposure to BPA or even its substitute, BPS, can lead to longstanding health consequences."
The US Food & Drug Administration last year published the results of a two-year animal toxicology study investigating the effects of BPA on health. It affirmed the organization’s prior position on BPA, suggesting current low levels of human exposure to the chemical are safe.
“A variety of endpoints were evaluated including growth, weight and tumor development,” said Stephen Ostroff, the FDA’s Deputy Commissioner for Foods and Veterinary Medicine, in 2018 when the early results of the study were released. “Overall, the study found 'minimal effects' for the BPA-dosed groups of rodents. The report did identify some areas that may merit further research, such as the increase in occurrence of mammary gland tumors at one of the five doses, in one of the groups.”
A study published late last year, however, cast doubts on the FDA research, claiming human exposure to BPA has been vastly underestimated. Traditional urine-based measurements have been used to assess human exposure to BPA and other chemicals, but the study presented a new method of measuring BPA metabolites in human urine and discovered levels up to 44 times higher than the average for American adults reported by the National Health and Nutrition Examination Survey could be detected in some samples.
“This study raises serious concerns about whether we’ve been careful enough about the safety of this chemical,” said Washington University Professor Patricia Hunt late last year. “What it comes down to is that the conclusions federal agencies have come to about how to regulate BPA may have been based on inaccurate measurements.”
The debate will certainly continue surrounding the potential harms from BPA exposure but at the very least it seems clear bisphenol substitutes such as BPS result in virtually identical effects. So, whether or not you agree BPA is harmful, the label “BPA-free” may not mean much at all if it simply has been replaced with chemicals such as BPS.
The new study was published in the journal PNAS.
Source: University of Missouri