It's used almost everywhere. It's in almost all of us. It does weird things to rodents and it may be doing weird things to us—but it's tough to be certain.
Bisphenol-A (BPA) has become a litmus test for how people view
environmental health and the risks of common household chemicals—as I
wrote in a long story for TIME
earlier this year. The chemical has countless industrial uses, most
often in the epoxy liner of cans and in plastic bottles. But BPA is also
an endocrine disruptor, meaning that it has the capacity to mess with
our hormones and potentially impact health—especially in developing
fetuses—even at relatively low doses. (Because they can mimic
hormones—which cause enormous changes in our bodies even at relatively
low amounts—the dose-response relationship used to evaluate traditional toxins like lead may not work with BPA.)
Green advocates like the Environmental Working Group have pushed hard to restrict and even ban BPA, citing the potential risk to human health, while industry groups like American Chemistry Council have fought tooth and nail to keep the chemical in use, casting doubt on the animal studies that have shown harm from BPA. In the U.S. so far the result has been something of a stalemate—public worry about BPA is definitely on the rise, especially in the media, and professional groups like the Endocrine Society have raised their own warnings about the chemical, but there's been no real change in regulation yet from the U.S. government.
Beyond our borders, however, governments are swinging into action. Yesterday Canada—with very little fanfare—declared
BPA a toxic substance, both to the environment and to public health.
The listing doesn't mean that all BPA will need to be banned
immediately—Canadian officials said that the declaration would be the
first in a multi-step process to better regulate BPA. By listing the
chemical as toxic, it's easier for officials
to ban the use of BPA in specific products through regulations, rather
than amending laws or writing new legislation. Canada has already banned BPA in baby bottles,
and this new listing will likely bring an end to food-related uses for
BPA, in bottles and possibly cans as well. Here's an excerpt from the
Canada Gazette explaining the decision:
Concern for neurobehavioural effects in newborns and
infants was suggested from the neurodevelopmental and behavioural
dataset in rodents. Given that available data indicate potential
sensitivity to the pregnant woman/fetus and infant, and that animal
studies suggest a trend towards heightened susceptibility during stages
of development in rodents, it was considered appropriate to apply a
precautionary approach when characterizing risk to human health.
Therefore, it was concluded that bisphenol A should be considered as a
substance that may be entering the environment in a quantity or
concentration or under conditions that constitute or may constitute a
danger in Canada to human life or health.
The Canadian move was done in the face of intense opposition from the
chemical industry, which was quick to respond to the decision. Here's
Steven Hentges of the American Chemistry Council:
Just days after the European Food Safety Authority (EFSA)
once again confirmed that BPA is safe for use in food-contact items,
Environment Canada's announcement is contrary to the weight of worldwide
scientific evidence, unwarranted and will unnecessarily confuse and
alarm the public. This puts Environment Canada at odds with the recent
conclusions of EFSA, the U.S. Food and Drug Administration, and the
German Federal Institute for Risk Assessment, all of which have
concluded that BPA is safe in contact with food. The decision also
appears to contradict the very recent opinion of Health Canada, which
stated in August that ‘the current dietary exposure to BPA through food
packaging is not expected to pose a health risk to the general
population, including newborns and infants.
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As Hentges points out, the European Union's own food safety watchdog just issued its own report on BPA, and found no need
to change the limit on BPA exposure from food containers. The experts
acknowledged that animal studies had found evidence of health impacts on
the nervous system and on cancer susceptibility—but they felt that
wasn't enough to prove a risk to human health. Meanwhile in the U.S.,
half a dozen states have already moved to ban BPA in children's
products, but the federal government still hasn't taken any action—like
the E.U., the FDA has said there isn't yet sufficient proof of harm in
humans. But further studies of BPA are ongoing at the federal level, and
Canada's decision will likely only increase the pressure on the FDA to
take stronger action.
So who's right? As the New York Times put it in a long examination of BPA last month, there's a lot of data and very few clear answers:
Most of the evidence against BPA comes from studies that
find harmful effects in rats and mice at low doses comparable to the
levels to which people are exposed. Sometimes the results seem downright
weird, indicating that low doses could be worse than higher ones. There
is sharp disagreement among scientists about how to interpret some
research. The disputes arise in part because scientists from different
disciplines — endocrinologists versus toxicologists, academic
researchers versus those at regulatory agencies — do research in
different ways that can make findings hard to reconcile.
The biggest unanswered question is whether low doses — the kind to
which most people are exposed — can have lasting, harmful effects in
fetuses and young children. Dr. [Linda S.] Birnbaum, [director of the
National Institute of Environmental Health Sciences, part of the
National Institutes of Health], said it was crucial to find out for sure
whether the low-dose effects in animals really occur. “We have hundreds
of studies that show they do, and then some that don't,” she said.
and for risk tolerance. Vastly improved diagnostic technologies has
allow us to examine the work of chemicals on our bodies even at very,
very low levels—levels that would have been ignored in the past. But
it's tricky, to say the least, to go from animal studies to human
effects—especially because you can't ethically run a double-blind BPA
test on actual human subjects. If you ascribe to the precautionary
principle—as do environmental health experts like Dr. Devra Davis—you'll
look at the worrying animal data on BPA and say we should act now, in
advance of final confirmation that might never come. If you're more
skeptical—or you represent an industry that would bear the brunt of the difficult task of banning BPA—you'll likely say we should wait and see. And wait some more.
about the possible impact of chemicals in the environment—especially on
pregnant women and developing fetuses. (See Annie Murphy Paul's great TIME cover story
on fetal origins and how the first nine months shape your life.) And
our system for regulating chemicals is an outdated legal mess—as I wrote
about earlier this year for TIME.
The science will never be fully certain, but the pendulum is moving in
the direction of a greater emphasis on safety—and I think it's time.