“Today more than ever before, science holds the key to our survival as a planet and our security and prosperity as a nation.  It’s time we once again put science at the top of our agenda and worked to restore America’s place as the world leader in science and technology.” – President Barack Obama, Executive Order regarding Scientific Integrity, March 2009

You may recall recent debate regarding the compound bisphenol A (BPA).

BPA is a compound used in the manufacture of polycarbonate plastics and epoxy resins used in food packaging.  BPA is vital to food quality as it stops metals and other materials from coming in contact with the food and making it unpalatable.  It also is vital to food safety, as it helps to prevent food spoilage in canned goods which could lead to contamination from deadly pathogens such as botulism.  It has been safely used in food packaging and other applications as a key tool in consumer protection for well over 40 years.  

The Controversy
The U.S. Food and Drug Administration (FDA) has approved the use of BPA for decades in food packaging and through extensive oversight and testing, affirmed its safety for all consumers.  The regulatory agencies responsible for food safety in Europe, Japan, and Australia have all reached the same conclusion.  Health Canada also said there was no risk from use in packaging.  Even the Developmental and Reproductive Toxicant Identification Committee (DARTIC) of the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) determined that BPA should not be listed under California’s Proposition 65.  Of the data and testimony reviewed by the panel of experts, physicians, and public health professionals, none offered clear evidence of risk to human health.  The panel also concluded there was not evidence [of risk to human health] to warrant any consumer warnings.

This consensus may surprise many consumers who have heard in the media that there are “hundreds of studies” that prove BPA is dangerous, and that the chemical should be banned.  Much of this media attention was driven by two determinations that BPA may be of some concern.  The National Toxicology Program (NTP) found that there may not be enough data about BPA, so that there is “some concern” about it.  But that can be said of almost every chemical in the universe.  Environment Canada reached a determination that BPA was not a health risk, but took action because there was a decision that the margin between exposure and effects in animals was not great enough.  It acted out of an abundance of caution.

Why the confusion?
Most consumers do not know about the regulatory nuances that caused the different conclusions.  They also may not be familiar with the underlying principles used to determine whether scientific evidence is suitable or unsuitable for making regulatory decisions.  The key principle for any scientific study is replication—can the findings of one study be reproduced.  Can the results of one study be replicated by another scientist in another laboratory?  Do the results hold up in a larger, more statistically powerful study?  If you can’t reproduce a finding, something was probably wrong with the original study.  Replication is the underlying basis for all of science.  In the case of BPA not all studies can be replicated.  That means the findings of those studies are questionable.

Second, not all studies are meaningful to human risk assessment.  There are many studies for many chemicals with results that simply cannot be interpreted for human health.  They may be interesting facts, but the data have no role in assessing human risks.  Many studies of BPA fit into this area—interesting facts with no meaning to human health.

While some studies suggest an adverse effect at very low doses, these effects have not been reproduced in more than 10 carefully controlled, high quality, reputable studies. One of the latest of these studies (Ryan, et al.) was conducted by the U.S. Environmental Protection Agency (EPA) and published in one of the world’s leading toxicology journals, Toxicological Sciences.  The work was criticized in a letter to the editor by a person extremely vocal about BPA’s potential toxicity, Dr. Frederick vom Saal.  In a response, Dr. Earl Gray, one of the study’s authors and the EPA’s senior reproductive toxicologist, explained in great detail why critics of BPA were misleading journalists, politicians, and policymakers to make policy decisions with little regard to the science.

While vom Saal, et al. describe the Ryan et al. study as “flawed,” regulatory agencies that recently reviewed Ryan et al. did not concur—and described it as useful for risk assessment.  In contrast, “a significant percentage of publications that reported effects of BPA at low dose levels were described as ‘inadequate’ for methodological or statistical reasons, ‘not replicable,’ ‘extremely limited,” or of uncertain toxicity and relevance to human health risk assessment.”

The entire rebuttal can be found in Toxicological Sciences, along with a companion article by Richard Sharpe, Britain’s leading expert on endocrine disruption.  The “Toxicological Highlight” published in Toxicological Sciences, explains why it is irrational to reject the scientific protocols the EPA used to determine that BPA is not a risk to consumers.  Dr. Sharpe goes on to validate Ryan and sharply criticizes the work of vom Saal.  He says, “The results from Ryan et al. are unequivocal and robust and are based on a valid and national scientific foundation.”  In the article, he continues to confirm that based on the Ryan et al. study there were no “discernable adverse effects” in regards to human exposure.  Dr. Sharpe has also weighed in on BPA in the British media where he provides a clear scientific commentary on why BPA is safe.

The FDA has for years supported the safe use of BPA.  However, “new results from recent studies using novel approaches” have presented a new set of questions and conclusions about BPA’s safety.  FDA has requested new data for BPA so it can evaluate everything.  Scientists have for years confirmed the safety of BPA and other (food) compounds based on a guiding set of principles which still hold true—even in today’s fast-paced communications and political environment.

Science is normally the arbiter of issues like BPA, but not all science is equal.  Decisions about BPA and other food components should be held to the most rigorous scientific standards we have today.  Not every published scientific study will meet that standard.  Some of the studies on BPA do not, regardless of the publicity that surrounds them.

Science being the underpinning of regulatory decisions, such as the safety of BPA, is consistent with the President’s point that, “it’s time we put science at the top of our agenda.”  Misinformed efforts to keep our food supply safe could result in the unintended consequences of placing the food supply’s safety in jeopardy.