A new study published in the journal Toxicological Sciences looked at the concentrations of a toxin called bisphenol A (BPA) in the blood and urine after a single-day moderate dietary exposure. The authors found that people eating three meals per day from cans lined with BPA had large spikes in their urinary output of the chemical, but that very little BPA was found in the blood stream.
An industry group quickly released a statement suggesting that this article was definitive evidence of the safety of BPA exposure from cans. It is in fact no such thing.
First of all, the study provides definitive proof that BPA from cans leads to spikes in urinary output, a finding that would be impossible if it were not absorbed. Second, this study included no measures of safety, only measuring some of the ways BPA travels through the body (a study called pharmacokinetics).
Finally, and perhaps most importantly, the blood stream is not the only place BPA ends up. In particular, it seems to have an affinity for fat storage areas. Unless the researchers measured intake versus urinary output (or better yet, did some radiolabeling), this research model does not prove that BPA doesn’t store in the body.
The Center for Science in the Public Interest has been keeping track of some of the concerns related to BPA exposure. In particular, esotrogen-like effects in children appear to be of concern with exposure to this agent and related compounds. The EPA has not yet established a safe upper intake for BPA exposure since these estrogenic effects were first noted.
For the sake of perspective, BPA is probably not one of the biggest environmental health risks we face. The EPA CERCLA list, for example, does not rate BPA among its top 200 priority items (although other estrogen-mimicing chemicals are prominently featured).
I have been very disappointed to see a recent backlash movement against environmental science, with many claiming it to be the equal and opposite force to climate science or evolution denial (here’s a particularly egregious example).
In a sense, I agree that some of the stuff I read about BPA is a bit overblown or one-sided. But we need to continue to do good science to ensure the safety of the chemicals that go in our bodies every day. Single studies don’t prove safety, and sometimes it really does take a long time to observe the truth about adverse health effects.
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