Bisphenol A - The Story of Political Toxicology

Bisphenol A, or BPA, is a useful, even critical industrial chemical used to make such diverse products as polycarbonate food containers, baby bottles, can coatings, and dental fillings. It is also the subject of countless reports that warn of its dangers, despite the fact that U.S., European, and Canadian regulators have vetted the chemical compound and say it is safe for its intended uses.

Even so, the media, including a virtual army of bloggers, continue to cite contradictory and often irrelevant studies to propel public opinion toward pressuring lawmakers for unwarranted legislation, banning the substance at state and federal levels. The Canadian government also is considering a ban. Are their concerns based on solid science? Not really. Rather, it is based on the public's aversion to any risk, no matter how remote. Yet, while the public has become less risk tolerant, our regulatory agencies have not caught up, which is a good thing. It is impossible to eliminate risk entirely from our lives. The question more properly stated is how much risk is acceptable, and whether the science supports the idea that there is any risk to begin with.

Researchers Can't Reproduce Early Study

Take the case of BPA. Over 10 years ago, Frederick vom Saal, a University of Missouri biology professor, reported to the National Academy of Sciences that BPA may cause irregularities in mouse fetuses upon parental exposure at levels on the order of 50 quadrillionths of a gram. Vom Saal noted that the effects are observed only at low doses but not at higher doses, contradicting a fundamental tenet of toxicology that "the dose makes the poison," and eliciting considerable reaction from the toxicology community.

Numerous government and private sector scientists have unsuccessfully attempted to reproduce vom Saal's work. However, a comprehensive set of studies conducted by the National Toxicology Program (NTP) reports that BPA presents virtually no safety hazard. A review of the now massive data set concerning BPA prompted the FDA to comment that "exposure levels to BPA from food contact materials, including for infants and children, are below those that may cause health effects." It goes on to say that alternatives to BPA-containing baby bottles are available to concerned consumers.

International Agencies Confirm Safety

The European Food Safety Authority says that "the available studies cover the majority of endpoints considered relevant for assessment of reproductive effects and other toxicities and do not indicate the presence of effects on reproduction or development." Health Canada concurs, stating that "the average Canadian would need to consume several hundred cans of food per day to reach the tolerable level established by Health Canada."

In spite of this overwhelming evidence, organizations such as the Environmental Defense Fund and the Environmental Working Group, and publications such as Green Guide, Tree Hugger, and Salon use their websites to continue the call for a ban on BPA in consumer products.

Adverse Study Is Misleading

In September 2008, The Washington Post published the story, "Chemical in Plastics Connected to Health Problems in Monkeys," and the New York Times published an editorial pointing to a study done at the Yale University School of Medicine as proof of the evils of BPA and substantiation for their continued call for a legislated ban of its use in consumer products. Ultimately, a number of major retailers and manufacturers of BPA-containing products are now putting a ban into effect in their stores and factories.

However, the study that the newspapers cite is misleading, because test animals were exposed to BPA through subcutaneous injections. Humans are exposed by ingesting miniscule amounts that are only a small fraction of the exposure achieved by injection. Furthermore, the body excretes ingested substances rapidly, while subcutaneous injections result in a much longer chronic exposure.

Unfortunately, and regardless of the scientific substantiation, public opinion is easily swayed by media accounts that question a product's safety. As a result, manufacturers must exercise the utmost care to demonstrate product safety in a scientifically sound and legally defensible manner. And they must protect that product from attention that may alter its public perception in a negative manner.