The Tangled Story of Bisphenol-a – A Preview

So we’re all carrying around small traces of the chemical bisphenol-a (BPA), used to make polycarbonate food and drink containers, epoxy coating for canned foods and sealants in dentistry.

And, according to the Chapel Hill consensus published in August 2007 in Reproductive Toxicology (Volume 24, Issue 2 behind a firewall, but I found a draft copy here), these levels of exposure are within the range at which very subtle, adverse health effects have been observed in laboratory animals. As yet, the occurrence of similar effects in humans hasn’t been attributed to bisphenol-a exposure; then again, it’s very challenging to link specific health effects observed in human populations to specific environmental exposures (for example, where do you find an unexposed control population).

Many conservative and libertarian types prefer that government keep out of the business of regulating chemicals in the environment, particularly those chemicals associated with commercially successful products. Their preference is to let the market squeeze out the problem chemicals – if those products are objectionable or harmful, then people won’t purchase them, and those products with the offending chemicals will disappear from the marketplace and won’t be a source of exposure.

However, markets work imperfectly when information is imperfect. There’s potentially a long latency period between exposure and the occurrence of health effects (breast and prostate cancer; adverse behavioral effects) with bisphenol-a. These effects in human populations are not unique to bisphenol-a, and might be attributable to other causes and sources of exposure. Without being able to draw a convincing exposure-effect relationship, the costs of treating cancer cases, or educating behaviorally-impaired kids or adults, which might have been related to bisphenol-a exposure cannot be incorporated into the price of plastic products made from this substance. It is difficult to inform consumers about the risks associated with bisphenol-a; the scientific issues surrounding the health effects are complex, fraught with significant uncertainty and a little scary, particularly if you’re a women of childbearing age. The economic footprint of polycarbonates and epoxy coatings is large, meaning those affected industries have the resources to shape the public debate around this substance.

This wasn’t the bisphenol-a post I wanted to write, but I’m still bogged down trying to connect the dots on this chemical, and the story is taking longer to pull together than I’ve expected. The story has become extremely tangled and hard to follow, with both scientific and political elements to it. See for yourself, at the National Toxicology Program’s Center for the Evaluation of Risks to Human Reproduction (CERHR) web site. While it is important to remain open to the possibility exists that leaching doesn’t produce significant health effects, making a decision that the risks from bisphenol-a are insignificant (i.e. take no further steps to regulate polycarbonates and epoxy resins contacting foods) with the current state of knowledge would be more of an act of faith rather than reason. In addition, it is sadly apparent that the mainstream media in its current form is not up to the task of informing people adequately about this issue. A good story, which I’ve discussed previously, can be found at PLOS. However as I’ve dug into this issue, I’ve found that that story only scratches the surface of this issue. Still it’s a better start than you’ll find in the mainstream media.

There are alternatives to polycarbonate sports bottles and childrens’ sippy cups. For those of you who don’t wish to wait for the scientific assessment to grind to completion, a precautionary approach in the face of the uncertainties about the health outcomes could be to turn to those alternatives. The alternatives to canned foods might be a bit more difficult, but there are some resources available online to find those alternatives (I’m compiling that information too for later posting, but feel free to Google “bisphenol-a free” if you want to read ahead).