Last month, we reported that bisphenol-A (BPA) used in plastic bottles and cans could not only inflict long-term damage on those who ingest it; it could also cause an immediate spike in blood pressure. At that time, we recommended that you drink out of BPA-free containers.
Apparently, we weren't specific enough.
A chemical called bisphenol-S (BPS) thought to be a safe replacement for BPA, which is banned for use in baby bottles and sippy cups, also causes developmental problems in fish embryos, according to a new study published in Proceedings of the National Academy of Sciences.
"A lot of the alternative chemicals have not been adequately tested because they don't have to be," lead author Deborah Kurrasch told The Washington Post. "A compound is considered safe (by the Food and Drug Administration) until proven otherwise."
For the study, researchers exposed zebrafish embryos to concentrations of both BPA and BPS at levels found in the Bow and Oldman rivers of southern Alberta, Canada — which are very low, in both cases. To the scientists' surprise, they found that exposure to these chemicals altered the timing of when neurons formed in the brains — which resulted in hyperactivity.
One of the most significant findings is that low doses can actually be more harmful than larger ones.
"Finding the mechanism linking low doses of BPA (or BPS) to adverse brain development and hyperactivity is almost like finding a smoking gun," said co-author Hamid Habibi, in a press release.
However, we should keep in mind that this study was performed on zebrafish, not humans. The researchers chose zebrafish because, according to the study, they share 80% of their genes with humans and are considered a good model for studying human brain development. They're good, but certainly not perfect. Fish, obviously, live in water, which exposes them much more to the chemicals in it, while humans are only exposed to trace amounts of chemicals when they drink water from a chemical-lined container.
Regardless, just because a bottle or can says "BPA-free" doesn't mean it's necessarily safe. We should all be wary of companies that just swap one chemical for another without proving the safety of the replacement chemical.
Further research clearly needs to be done to determine if the BPS also affects human fetuses, but the study authors recommend that pregnant women limit their exposure to items containing bisphenols — which can be found in plastics and sales receipts.
So while there's no real reason to be living in fear of the containers from which you drink, it may be wise to swap that plastic water bottle you tote around with you all day for a glass or aluminum bottle. It's better for the environment, too.