November 11, 2009 11:10 AM ET | Ford Vox
Bisphenol-A, better known as BPA, is the building block of polycarbonates and epoxy resins, plastics that have facilitated modern life. (They’re in microwave containers, baby bottles, laptops, and even canned foods.) Tiny amounts circulate in the bodies of more than 90 percent of Americans. And now a team of Chinese and U.S. scientists says it has linked the stuff to sexual dysfunction in men. Even before today’s news, plenty of people were getting the willies about BPA. Should this news make you feel less virile? Let’s take a closer look.
Six years ago, De-Kun Li, a senior scientist at Kaiser Permanente’s research arm, and his colleagues were already alarmed about BPA because of a steady stream of studies showing that BPA alters tissues in the reproductive organs and offspring of rats and mice. But there’s a heated debate among statisticians, toxicologists, and endocrinologists about which animal models are relevant to human disease and about the paradoxical way BPA seems to work. Unlike typical poisons or carcinogens, more is not always worse and less is not always better. In many of the studies, BPA changes animal tissues only at specific low concentrations and only at particular stages of the life cycle.
“BPA is not a toxin. It’s not going to kill you,” Li told me in an interview. It’s a form of artificial estrogen that could disrupt the endocrine system, where hormone signals like estrogen and testosterone subtly influence the behavior of cells throughout our bodies. Extra estrogen in females isn’t good (it’s known to increase breast cancer risk, for example), and it can interfere with testosterone in men.
But there’s precious little demonstration that this is happening in people and not just in lab animals. “The argument ultimately comes down to: ‘Where is the human evidence?’ ” says Li. That poses a dilemma. Li believes animal evidence alone won’t overcome industry’s vigorous defenses or satisfy government regulators—but he knows no university oversight panel will ever approve human BPA experiments.
Li did the next best thing, finding four factories in China where large quantities of BPA are generated (directly or in producing other materials) and studying the men who worked there. If BPA isn’t dangerous in such places, he figured, we don’t need to worry. He split up the exposed workers into three levels based on personal air sample monitors, job roles, and length of employment, and confirmed with air and urine sampling that they were exposed to much higher levels of BPA than similar men in the same city who didn’t work at the factories.
The research identified a pattern: Higher exposures led to more sexual frustration. The men in the factories had four times the rate of erectile dysfunction of the men who didn’t work there. They complained about ejaculation problems seven times as much. And overall, they were four times as likely to be disappointed with their sex life.