BPA-free plastic water bottles, food containers, and sippy cups may be no safer than those containing bisphenol-A. After several studies over the past decade showed that this plasticizer leeches into food and drinks, enters our bloodstream, mimics our hormones, and potentially triggers a host of health problems, many plastics manufacturers ditched BPA. However, they merely swapped in its chemical cousin, bisphenol-S, and until very recently, BPS's impact on the endocrine system was a big question mark. But now the evidence is quickly piling up, and it's looking to be just as hazardous as BPA.
In the latest study to blast BPS, endocrinologists from UCLA examined how low levels of this chemical affected zebrafish. Not only did it speed up the development of embryos and cause premature births, but BPS also messed with key endocrine cells in the offspring's brain. This type of hormonal interference can ransack the fish's reproductive capabilities throughout life, says senior study author Nancy Wayne. Additionally, BPS mimicked thyroid hormones, posing further problems for future brain function.
Since it's unethical to test-drive toxins on living humans, the best info researchers can gather on BPA and BPS comes from animal studies like this, as well as from analyzing human cells in petri dishes. "This is the second fish species in which we've seen bisphenols have a significant effect on the thyroid pathway — and that's huge," says Wayne. Messing with the thyroid system at any stage of life is problematic, she notes, but especially during embryonic development, because the thyroid hormone plays such a critical role in brain development. "To me, this is very frightening," Wayne says.
According to Wayne, previous tests on cultured human cells have shown that cancer cells proliferate in the presence of either BPS or BPA. Based on this evidence, she fears that the dramatic increase in our use of plastics over the past several decades is directly tied to the uptick in prostate and breast cancers. "We can't say for certain that these chemicals are causing cancers — it isn't like we've found one smoking gun," Wayne says. However, she's confident the higher rates of reproductive-system cancers point to environmental changes, and these plasticizers are likely one of many culprits.
Although our bodies metabolize both BPS and BPA very quickly, the problem is we are re-exposed to them daily. That means they're constantly in our bloodstream. "We could take a blood sample from you any day of the week, and we'd be able to detect these bisphenols in your body," Wayne says. The problem doesn't stop with these two chemicals, either. "There are likely dozens of endocrine disruptors in your system at any time," Wayne says. "At the very least, they'll have an additive effect on your health over a prolonged period."
Your best protection against BPS, BPA, and other endocrine-disrupting plasticizers is pretty simple: Avoid plastic as much as possible. Don't drink out of it, don't store food in it, and never heat it in the microwave, which makes it more likely to transfer onto your food or drink. Take it from Wayne, who's been dodging plastic ever since her team started studying BPA back in 2007. "Those preliminary results were so dramatic and frightening that I immediately went home and threw out everything in my fridge, freezer, and cupboards that was kept in plastic," she says. "I tossed out hundreds of dollars' worth of food and started over. Now I store most everything in glass.