Bisphenol-A (BPA) is a chemical that is used in a wide variety of items—rigid plastics, lining in canned food and beverage products, and even thermal paper used for receipts. It has been subject to hundreds of studies over the past few decades, making it one of the most studied chemicals in wide use today.

BPA is currently categorized as “general recognized as safe” by the U.S. Food and Drug Administration (FDA). The FDA released two of the largest and most rigorous studies of BPA in early 2014 which, according to Daniel Doerge, a research chemist with the FDA’s National Center for Toxicological Research, “both support and extend the conclusion from the U.S. Food and Drug Administration that BPA is safe as currently used.”

Despite such a huge volume of research on BPA, the chemical still remains highly controversial. In the United States, environmental activist groups such as the Environmental Working Group and the Natural Resources Defense Council, call for the complete ban of the chemical. A division of the National Institute of Health, the National Institute for Environmental Health Studies, has funneled millions of dollars to researchers working to find negative health effects of BPA. And state and federal legislators are working to pass legislation to ban the chemical in certain applications.

Why are health activists scared of BPA?

BPA is an endocrine disruptor that can mimic estrogen. However, studies have found that BPA’s ability to mimic hormones is extremely weak. As an article in Toxicological Science wrote, BPA’s estrogenic effect is “so weak that even at levels of exposure 4000-fold higher than the maximum exposure of humans in the general population there are no discernible adverse effects.”

There are studies that have associated BPA with health problems ranging from autism to prostate cancer, prompting health activists to call for BPA’s ban. However, these studies have largely been dismissed by the larger scientific community for a number of reasons.

• Small sample size. Often these studies rely on just a small number of test subjects, making it harder to tell if any weak associations of BPA with health effects are merely accidental.
• Injecting BPA directly into animal subjects rather than through oral ingestion. Most humans are exposed to BPA orally, not through injections. BPA is metabolized by the body differently when it is ingested orally, therefore studying the impact of BPA when injected directly into rats does not accurately predict health effects in humans.  The National Toxicology Program agrees with this problem, “There is scientific consensus that doses of bisphenol A administered orally and subcutaneously cannot be directly compared in adult laboratory animals because the rate of metabolism of bisphenol A differs following oral and non-oral administration.”
• Exposure to BPA at millions of times the typical level of exposure. Most of the studies that conclude BPA is a threat to public health expose subjects to BPA at millions of times the typical daily exposure level—even the FDA’s most recent study found negative health effects at exposure levels this high.

While there have been a few studies of low-dose exposure of BPA that have found health problems, the EPA notes “Regulatory authorities around the world reviewing these low-dose studies have generally concluded that they are insufficient for use in risk assessment because of a variety of flaws in some of the study designs, scientific uncertainty concerning the relevance to health of the reported effects, and the inability of other researchers to reproduce the effects in standardized studies.”

There is also a small group of researchers that have staked their careers on the conclusion that BPA is harmful and continue to criticize large studies that show the opposite. These researchers have received millions of dollars in grant money (often from governments) to study BPA and are personally invested in getting BPA banned. NIEHS alone has dedicated over $30 million to the study of BPA.  You can learn more about the motivations behind BPA research here.

What do major regulatory bodies say about BPA’s safety?

Most major regulatory agencies around the world conclude that BPA is safe the way it’s currently used. However, some agencies have banned the chemical’s use in children’s products as a precautionary measure. The U.S. Environmental Protection Agency explains this move: “For example, while acknowledging that science indicates exposure levels are below potential health effects levels, Canada is taking steps to ban BPA in baby bottles as a precautionary measure.”