"Just one word...plastics," a memorable line from the 1967 movie The Graduate, has taken on a whole new meaning. Then, plastics held all the future's promise. Now, we've come to fear them, in part because of the potential health dangers posed by bisphenol A, a chemical found in hard, clear plastics and most cans containing foods or beverages. The spotlight over the past year has been on rigid plastic baby bottles and plastic-lined cans of infant formula. That's natural, since babies are thought to be most vulnerable to BPA's reproductive health effects; in animal studies, exposure early in life increased long-term risk of uterine fibroids, endometriosis, decreased sperm counts, and breast and prostate cancer.
It turns out, though, that adults may be at risk, too. A landmark study of more than 1,400 people ages 18 to 74, published today in the Journal of the American Medical Association, found that those with the largest amount of BPA in their urine had nearly three times the risk of heart disease and more than twice the risk of diabetes as those who had the lowest levels. "Even those with the highest BPA levels still had levels way below the currently established 'safe' level," says David Melzer, an epidemiologist at the University of Exeter in England and coauthor of the study. Other researchers say there's enough evidence from previous animal studies to suggest that BPA is harmful to adults. BPA levels that are slightly elevated but still just one-fifth the safe dose limit established by the Food and Drug Administration trigger an alarming release of insulin in the pancreatic cells of mice—and higher levels lead to pre-diabetes or insulin resistance, says Frederick vom Saal, a biologist at the University of Missouri. BPA also suppresses the release of a hormone from fat cells that normally protects against diabetes and heart disease.
Babies, though, are still most at risk. "They're the most highly exposed to BPA through bottles and formula, so they get more on a per-pound basis," says Sarah Janssen, a physician and science fellow at the Natural Resources Defense Council. Babies also can't metabolize the chemical as quickly as adults, so it accumulates in their bodies, posing problems for fragile, developing organ systems. In fact, the government's National Toxicology Program recently concluded that there's enough evidence to express "some concern" over BPA's detrimental effects on the brain and reproductive organs in children.
So why is BPA still allowed in food products? While public interest groups like Consumers Union have issued calls to ban BPA in all such products, the FDA has declined to do so. The agency declared last month that "products containing BPA currently on the market are safe and that exposure levels . . . are below those that may cause health effects." This decision astounded vom Saal, Janssen, and other environmental health activists, who accused the FDA of relying on only two studies, both funded by plastic manufacturers. The FDA is holding a hearing today to address the health concerns surrounding BPA, but the agency has not indicated whether it will change its stance.
Congress could override the FDA policy by passing legislation that bans the use of BPA in baby bottles and infant formula packaging. And Sen. Chuck Grassley, a Republican from Iowa, today called on the agency to explain how it chose which studies it included in its safety assessment of BPA.
Industry representatives argue that the plastic epoxy resins used to line cans will be particularly difficult to replace. "Acidic foods will corrode the metal of cans, so you have to have a coating in there; it's the reason why canned tuna has a shelf-life of three to four years," says Steven Hentges, a chemist and BPA expert with the American Chemistry Council, a trade group. "Finding an alternative liner that works as well and is safer would not be easy."
Melzer offers a different reason for holding off on a ban of the compound: It's possible, he says, that BPA isn't to blame for ailing hearts or diabetes and is instead an innocent bystander in people with those conditions. Someone who consumes too much canned beef ravioli and a daily six-pack of cola, say, might develop poor health because of the excess calories and saturated fat and, separately, might end up with high BPA levels from the foods' packaging material.