An editorial in The Wall Street Journal on Aug. 8 described a recent EPA-funded study, replicated in several labs, that should allay the fears of parents and other consumers that exposure to small quantities of bisphenol A may cause adverse health impacts. It should also raise troubling questions about the Department of Health and Humans Services' recent Report on Carcinogens (RoC), particularly the shaky science it used to classify styrene as “reasonably anticipated to be” a carcinogen.
BPA is an important chemical intermediate used to produce epoxy food-can linings, polycarbonate drinking bottles, cash-register tapes, vinyl ester resin for composite manufacturing and thousands of other products. Laboratory animals exposed to large quantities of BPA suffer developmental abnormalities and exposure has been “linked” to a variety of diseases, including cancer.
The recent EPA study involved human subjects fed relatively large quantities of BPA. The result: Levels of the biologically active form of BPA were barely detectable in subjects' blood and urine. In the large majority, concentrations were below the detection level, even using ultramodern sensitive analytic techniques.
In an interview posted July 25 at blogs.forbes.com, Justin Teegaurden, lead author of the EPA study, volunteered: “We can now say for the adult human population exposed to even very high dietary levels, blood concentrations of the bioactive form of BPA throughout the day are below our ability to detect them, and orders of magnitude lower than those causing effects in rodents exposed to BPA. For me, the simple takeaway is that if blood concentrations of bioactive BPA are much lower than those in this sensitive animal model, effects in the general human population seem unlikely at best.” Teegaurden's conclusion: The EPA study is “comforting news.”
The story of BPA provides important lessons for the composites industry as we fight federal regulators to obtain a scientifically valid assessment of the potential for styrene to cause cancer. One lesson is that conducting sophisticated science is difficult. It's easy to expose lab animals to abnormally high levels of a substance then react in panic when the rodents get sick.
It's also easy, when assessing chemical health risk, to follow the lead of the HHS' RoC by using default assumptions and shortcuts instead of rigorous weight-of-the-evidence methods.
A recent weight-of-the-evidence evaluation of the BPA database by the German Society of Toxicology found that “the available evidence indicates that BPA exposure represents no noteworthy risk to the health of the human population, including newborns and babies.” It may be that only top-level groups such as the GST or the U.S. National Academy of Sciences have the intellectual resources and motivation to conduct these quality assessments.
A second lesson is that the media and activists — for different reasons — have limited interest in a full analysis of what is typically a large and complex scientific database. Especially in relatively large doses, many substances can cause biological changes (i.e., toxicity) in mice. Taken out of context people can find these results to be very disturbing, especially if the animals have tumors or developmental toxicity. Often these results on their own tell us very little about human health risk, yet they get the attention of media and activists. On the other hand, the complete scientific picture, which often is more complicated and less exciting when it arrives, seems to be of little interest.
Good science can win in the end, but it takes a concerted and lengthy campaign. The real challenge is not so much bad science but the bad combination of politics and money. The Aug. 8 Journal editorial tells the story of Sigg Switzerland USA, the U.S. distributor of metal drinking bottles. “Sigg initially benefited from the BPA scare as consumers ditched their plastic drinking bottles. But once it transpired that the lining of Sigg's aluminum bottles manufactured before August 2008 also contained trace amounts of BPA, its U.S. distributor was hit with lawsuits and public vilification that sent it into bankruptcy. Where does the economy get those jobs back?”
U.S. manufacturing has been devastated in recent years. Let's not exacerbate the problem by pushing bad science — and ignoring the good.
Luchak is president of the American Composites Manufacturers Association, and president and CEO of Miles Fiberglass & Composites Inc. in Portland, Ore.