Bisphenol A

Regular exposure to bisphenol A from food, drink, and other sources means that the commodity chemical shows up at low levels in the urine of essentially everyone. That fact has created a lot of concern about how toxic BPA might be. But assessing the risk the chemical poses has turned out to be not so simple.

Primarily employed as a building block to make polymers, BPA has been used in an array of consumer goods since the 1950s. It’s a primary component of polycarbonate hard plastics found in reusable drink containers, DVDs, cell phones, eyeglass lenses, automobile parts, and sports safety equipment. The chemical is also a key component of epoxy resins that provide a protective layer inside food and drink cans. It’s found in dental sealants and in cash-register receipts as well.

That BPA has estrogenic activity—the ability to simulate the activity of the primary female sex hormones—is old news, dating back to about 1930. At one point decades ago, it was even considered for use as an estrogen replacement drug until better mimics were discovered.

More recently, however, hundreds of animal and cell-culture research studies have linked the chemical’s low-level estrogenic activity to obesity, diabetes, attention deficit hyperactivity disorder, reproductive health problems, heart disease, and breast and prostate cancer. Yet BPA’s safety status is in limbo because regulators think that the methods used in many of those studies haven’t been fully validated. Instead, regulators continue to rely more heavily on a few larger-scale industry-funded studies that used older, standardized assays and reported minimal ill effects at human exposure levels.

It would be easy enough to test the effects of BPA directly on people and settle the issue. That’s naturally out of the question because it’s unethical. So although the ubiquitous chemical is known to prompt some harmful effects, it remains just beyond science’s grasp to provide a definitive assessment of BPA’s safety. This confounding situation has led to a vigorous debate about what to do with BPA: ban it, restrict its use, or leave it alone.

As this debate has unfolded, the public has been bombarded with a steady flow of studies, reports, claims, counterclaims, conflicts of interest, lawsuits, and congressional inquiries regarding BPA. Both sides of the debate have been active in promoting their views to the media and the public. And both sides accuse each other of using spin tactics to create uncertainty about BPA, not unlike the socioscientific debates that have unfolded over cigarette smoking and climate change.

In a series of articles both in print and online, C&EN takes a broad look at the ongoing bisphenol A story.