Why be warry of BPA?
What makes BPA so worrisome? It falls into a class of chemicals broadly known as endocrine disruptors — that is, “any manmade chemical that in some way interferes with our body’s hormones and endocrine system,” says Andrea Gore, PhD, editor-in-chief of the journal Endocrinology. Although reproductive effects — for example, decreased sperm count, increased rate of miscarriage, and early-onset puberty — are perhaps the most widely publicized risk, BPA can also bind to receptors for hormones other than estrogen (and testosterone).
There’s now evidence, for example, that BPA may interfere with thyroid hormones — and the effects could be far-reaching. “Our body needs to have normal thyroid hormone levels in order for us to have normal metabolism,” Gore says. “This isn’t simply a matter of getting fat — every cell in our body has to undergo metabolism in order to survive. Our cells need to take in oxygen, they need energy, they need to get rid of waste products. If that doesn’t happen properly, cells will die.” There may also be behavioral effects of BPA, such as hyperactivity and aggressiveness, says Halden.
From the get-go, scientists have known that BPA has hormone-mimicking properties — it was originally discovered by pharmaceutical companies trying to develop estrogen-like drugs. As it turned out, “BPA is pretty weak at activating the estrogen receptor, so it was thrown away as a pharmaceutical,” Gore says. “BPA is not a very good estrogen but it’s a very good plasticizer. So it ended up making its way into plastics.” If its hormonal effects are weak, why does exposure to BPA even matter? At certain ages, children aren’t naturally exposed to any estrogen, making even a small amount of exposure significant. And over time, if you’re exposed to the chemical day after day, the hormonal effects can add up, even in adults.
And BPA has been shown to migrate out of plastic: A 2013 study in the journal Environmental Science & Technology, for example, found that the more water people drank from polycarbonate bottles, the higher their BPA levels tended to be. The study was conducted during the hottest months of the year, leading the researchers to conclude that sun exposure caused the chemical to leach from the bottles into the water — an effect that could be replicated by microwaving potentially problematic plastic, especially if the food you’re zapping is oily or fatty, says Halden.
“If you tested everybody in the U.S., Canada, and most of the industrialized world, you would find BPA in something like 95 percent of people’s urine,” says Schmidt. “BPA has a biological half life of about a day, so that means we’re all being constantly exposed to it.” (Keep in mind, plastic containers aren’t the only culprit: A major source of BPA exposure is the epoxy lining in canned foods.)
Luckily, BPA is being increasingly phased out, which means most containers designed for reuse are free of the chemical. “If you do a sensitive-enough test, eventually you will find something,” says Schmidt, which may explain, at least in part, why an often-cited studydetected endocrine disruptors in every type of plastic tested. What’s going on? Cross-contamination can occur during manufacturing, leaving even BPA-free containers with traces of the stuff, as well as other chemicals.
“Can you guarantee there’s not a single molecule of BPA or a phthalate in something? Probably not,” says Schmidt. “But that shouldn’t be the sole concern. In the grand scheme of things, the hazards that could potentially be associated with reusable plastic food containers may be outweighed by other things we have to worry about — for instance, what food is in those containers and how much of it we eat.”
So， BPA free glass food storage is the better choice for us to take the food.