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It seems like every
bit we eat or drink is shrouded in plastic. Plastic hugs our microwave burrito,
scrambles our eggs, houses our water and feeds our babies. But is it a problem
for our health? Well it depends on what kind of plastic, what you’re doing with
it, and whom you ask. Bisphenol-A, a plastic ingredient, may be on your mind
because its safety has recently been called into question.
Three big things must
be true for a plastic to harm you. First, it has to have something harmful in
it. Second, the harmful substance needs to get out of the plastic and into you.
And third, it needs to have enough of that stuff to do you damage.
Polycarbonate, a type
of plastic, meets at least two of these three criteria for harm. It contains an
ingredient, Bisphenol-A (BPA), which has garnered a lot of attention lately
because of its use in baby bottles and its potential to damage developing
humans and animals. Studies have found that BPA can migrate out of the plastic
into foods and beverages, and then into you.
The bonds that hold BPA molecules together in a polycarbonate can
disintegrate over time, when heated, or exposed to acidic or basic
substances. Because of this, the BPA is never really safely locked away. It’s that freewheeling, loose BPA that attaches to the food or
beverage in a polycarbonate container and then leaches into your body.
In the body, BPA acts
as an endocrine disruptor — masquerading as a sex hormone.
This is a particular problem for sexual development, which is dependent on
precise hormone signaling: Grow now! Develop hair! Don’t have breasts — you’re
a boy! Studies have shown that BPA can harm developing rodents, even in small
amounts. The question is whether it can harm humans in the amounts to which we
are regularly exposed.
This spring, the
Canadian health authority decided to try to ban baby bottles made from
polycarbonate plastic. Even though the authorities concluded that the amount of
BPA getting into people is less than a safe level, Canadian health officials
worry that even very low levels of BPA could harm developing
infants and children. Tony Clement,
Canada’s
Minister of Health said in his speech, "it is better to be safe than
sorry."
The United States
Food and Drug Administration says that for now, BPA is safe for humans of all
sizes and ages because more than three times less BPA gets into us than the
level the government deems safe (0.05 mg per kilogram body weight per day). But in a review
published in 2007 in the journal Reproductive
Toxicology, scientists argue that there have been more than 40
studies showing BPA causes harm in doses lower than the human safe dose.
Meanwhile, after
reviewing over 200 individual BPA studies, a National Institutes of Health
toxicology panel concluded that there is "some concern" that the
amount of BPA coming out of polycarbonate baby bottles or the lining of cans
can harm developing humans. "Some concern," the report explains,
means halfway between "negligible concern" and "serious
concern." It’s not definitely deadly, but it’s not safe either.
To sum up, people are
not exposed to BPA at the level that the United States government says is
dangerous. But many doubt the accuracy of that "safe level." If
knowing there’s even a small bit of BPA in polycarbonate bottles is enough to
put you off, it may be time for you to switch to another food/beverage storage
system.
This answer is provided by Scienceline,
a project of New York
University's Science,
Health and Environmental Reporting Program.
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