There's no denying that bisphenol A (BPA), the latest headline-making toxin, is ubiquitous — it's in hard plastic water bottles, the lining of food and beverage cans and, most disturbingly, the plastic baby bottles that most parents commonly use. What's less clear, however, is exactly what effect BPA has on human health.
That was the subject of an Oct. 31 daylong meeting of the Food and Drug Administration's (FDA) Science Board. Earlier last week a panel commissioned by the Science Board released its review of the FDA's safety report, which concluded in August that current levels of BPA exposure posed no real health risk. The Science Board convened Friday to discuss the panel's findings — a highly critical 17-page review that deemed the FDA's conclusions flawed — and to hear comments from the public about whether the compound should be banned from food and beverage containers. The board will now forward the review along with the FDA's original safety assessment to FDA chief Dr. Andrew von Eschenbach. The FDA has until February 2009, when the Science Board next meets, to respond.
Why the renewed uproar over plastic? Since the FDA completed its original analysis in August, additional data on the potential health effects of BPA have emerged, linking high levels of BPA exposure to increased risk of heart disease and diabetes and even a decreased sensitivity to chemotherapy in cancer patients. The compound is also linked to developmental and brain effects in infants; BPA is known to mimic the hormone estrogen in the body, which can cause changes in developing fetuses and infants. "There is enough evidence today for the FDA to take the precaution and to certainly get BPA out of infant products," says Urvashi Rangan, senior scientist and policy analyst at Consumers Union. "Even more, consumers should not be ingesting this substance while the science is being figured out."
The FDA's initial assessment — which it has not rescinded — that "an adequate margin of safety exists for BPA at current levels of exposure from food-contact uses, for infants and adults" was based on data available at the time. Back in April, for example, the National Toxicology Program, which is part of the National Institutes of Health (NIH), released a preliminary report expressing "some concern" that according to studies done in animals, BPA could have neural and behavioral effects on fetuses, infants and children at current levels of exposure. Recent surveys by the Centers for Disease Control and Prevention (CDC) had suggested that exposure is widespread, showing that 93% of Americans excrete some BPA in their urine. Still, the weight of the evidence, mostly from animal studies, did not suggest a significant health risk in humans, according to the FDA.
But last week, the reviewing panel disagreed, saying the FDA's analysis excluded several important studies on BPA in animals. The panel also questioned the quality of some of the included studies and found that the FDA did not incorporate enough infant-formula samples in its evaluation. According to the panel review, the FDA's safety report "creates a false sense of security" and the agency's margins of safety for BPA exposure are, in fact, "inadequate." Says Tracey Woodruff, director of the program on reproductive health and the environment at the University of California, San Francisco, and a former Environmental Protection Agency scientist: "Unless the evidence is very compelling, you don't get such a strong statement from a group of scientists."
It's now up to Von Eschenbach to decide how to proceed. He may start from scratch and commission another report that includes the most recent findings on BPA; he may reject the panel's review and adhere to the FDA's original conclusion that BPA is harmless at current exposure levels; or he may ban the chemical from baby products, as the Canadian government did in April. Or he may draw no further conclusions about BPA until additional studies can be commissioned and completed to answer some unresolved questions.
"While we have some idea of how much BPA might leach from a baby bottle, there are intermediate steps between that and how much gets into an infant that we still need to model and establish mathematically," says John Bucher, associate director of the National Toxicology Program, which collaborates with the FDA, NIH and CDC. "And we don't have that yet." The FDA report maintains, for example, that a BPA exposure level of 5 mg/kg per day is acceptable. Health officials have determined that baby bottles can produce anywhere from 7 micrograms/g to 57.7 micrograms/g of BPA. The questions are: How much of the compound is absorbed into an infant's body? How much remains, and how much is excreted? And does that exposure come close to the FDA threshold?
The FDA can't answer those questions yet, but some experts argue that the agency doesn't need to wait to take action. "The Federal Government entered into a voluntary recall of the Teflon chemicals [in pots and pans] on less evidence than we have for BPA," says Woodruff, "because there was concern that people were chronically exposed to a chemical linked to some evidence of potential human harm." Woodruff says the estimated range of exposure to BPA for formula-fed infants is within the range of doses that have led to adverse effects in animal studies.
Until the government settles on a new assessment or action, experts say parents have the option of using BPA-free products — including glass, stainless steel and some innovative next-generation plastics that do not contain the chemical.