By Nina Shen Rastogi
Thursday, July 23, 2009
How dangerous to babies is bisphenol A? Lately, I've been seeing a lot of hubbub in the news over the chemical. They say it's in a lot of baby products, like bottles and sippy cups, and in hard plastic water bottles, too. But I can't tell if this is really a big deal or just an overblown chemical panic.
You can be forgiven for being confused: There's a huge mountain of data out there about bisphenol A, and every day it seems as if a study comes along linking the chemical to a new, scary condition.
It's certainly true that we're all regularly exposed to BPA, a synthetic chemical used primarily as an ingredient in the hard plastic called polycarbonate and in the epoxy resins that line most food and soft-drink cans. Small amounts of the chemical can leach from containers into our food, which may explain why a study conducted by the Centers for Disease Control and Prevention found that nearly 93 percent of Americans older than 6 had detectable amounts of BPA in their urine.
Does that make BPA a danger to our health? At very high doses -- thousands of times above what researchers estimate we're exposed to daily -- BPA causes problems in lab animals such as delayed puberty and lower body weight. Based on a high-dose study from the early 1980s, the current federal exposure limit is set at 50 micrograms of BPA per day per kilogram of body weight. To put that in perspective, one recent study worked backward from the CDC's urine data to conclude that normal adults are exposed to between 0.0235 and 0.2472 micrograms per kilogram per day.
The controversy over BPA comes from the hundreds of "low dose" studies that have emerged in the past decade, which suggest that the chemical is more of a problem than we thought. Yet there's quite a bit of dissension in the scientific community over how to interpret all this research. In the past few years, there have been a few attempts to wade through the flood of new data. In 2007, 38 researchers who have studied the chemical extensively signed a consensus statement asserting, among other things, that they were "confident" that commonly reported levels of BPA in humans were higher than those shown to have adverse effects in animals. Last year, the National Toxicology Program, a research division of the National Institutes of Health, expressed "some concern" -- the middle ranking on a five-point scale -- about BPA's effects, at current exposure levels, on the brains and prostate glands of fetuses, infants and children. (The program expressed "minimal" to "negligible" concern, however, on other developmental and reproductive issues.)
Meanwhile, most national regulatory bodies, aware of the low-dose studies, have determined that the research isn't conclusive enough to declare BPA a hazardous substance that should be avoided. In 2008, Canada decided to ban the sale of polycarbonate baby bottles but emphasized that it was doing so as a precautionary measure and that "the current research tells us the general public need not be concerned." The European Food Safety Authority recently reiterated its position that BPA is safe for regular use.
Here in the United States, the Food and Drug Administration released a preliminary risk assessment in August, concluding that "an adequate margin of safety" exists between the levels of BPA Americans get through their food (which it estimated to be 0.185 micrograms per kilogram of body weight a day for adults and 2.42 micrograms for infants) and the level at which harmful effects could be observed in two high-dose studies of rodents (5 milligrams per kilogram of body weight). Yet last month the FDA announced that it would reexamine its position, following a request from concerned congressmen and a highly critical peer review from the agency's science advisory board.
Given all this conflicting information, the Lantern isn't quite ready to panic but thinks it's appropriate to apply the precautionary principle in this case. If the Lantern were pregnant or had her own little Green Penlight, she would at least try to reduce the amount of canned food in her and her baby's diet and choose nonpolycarbonate baby bottles. (Finding one isn't difficult: In March, the country's six leading manufacturers announced they're phasing out BPA bottles from the U.S. market.) There are some trade-offs: For example, glass baby bottles (a popular replacement for polycarbonate) can shatter, and reducing your intake of canned foods can lead to more rotten vegetables and food waste.
Many green-minded folks have also made the move of swapping their Nalgene-style bottles for the stainless-steel variety. A recent Harvard study found that undergrads who spent a week drinking most of their cold beverages out of polycarbonate bottles had 69 percent higher BPA concentrations in their urine than before the study. Those elevated concentrations were still a bit below mean levels found in the general population, though, so it's not as if using a plastic bottle will send your BPA levels skyrocketing. Remember, stainless steel can have greater manufacturing impacts than plastic. If you make the switch, try to find an alternate use for your old bottle, because polycarbonate isn't usually recyclable -- a receptacle for loose change, perhaps?