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Tough Questions About a Hard Plastic

Plastics are one of the greatest inventions of all time, and modern-day life depends on them. They are ubiquitous—in everything from lightweight bottles, appliances, home insulation, and electrical wiring to winter coats, car seats, bicycle helmets, medical syringes, and heart stents. But we get many questions from readers about the safety of plastics—especially plastic bottles that contain bisphenol-A. Called BPA for short, this industrial chemical has made headlines lately because of concern that, by mimicking estrogen, it may cause developmental and reproductive problems, among other adverse effects. What risk, if any, does BPA pose?

BPA is used to make hard, clear, lightweight polycarbonate plastic—as in those virtually indestructible water bottles favored by hikers (not the disposable ones) and many baby bottles and sippy cups; it’s also found in the lining of most food and beverage cans. Trace amounts can migrate into foods and beverages, especially when the plastic gets hot. BPA has been used commercially since the 1950s, and exposure to it is widespread in developed countries. A large study last year by CDC researchers found that 93% of people tested had the chemical in their urine—with higher amounts seen in women and children. Though much of this BPA comes from food/drink containers, other potential sources include dust, water, and soil.

Numerous lab and animal studies have shown that BPA exposure in early life, even at low doses, causes cell and tissue changes that may have long-term consequences, such as early puberty, behavior problems, breast and prostate cancer, altered immune function, and metabolic problems. New lab research also suggests that BPA can interfere with chemotherapy treatment. But studies in people are limited, and what happens in animals and test tubes may not happen in humans. The potential risk for adults is particularly unclear. Still, in a large new study in the Journal of the American Medical Association—the largest human study to date—high levels of BPA in urine were associated with heart disease, Type 2 diabetes, and abnormal liver enzymes—though this does not prove that BPA is the cause.

BPA, NIH, FDA . . . SOS

Government agencies that assess the safety of chemicals in our food supply have been at odds with one another about the dangers of BPA, as have various independent scientific panels. Last spring the National Toxicology Program at the National Institutes of Health (NIH) reported "some concern" (3 on a scale of 1 to 5) that BPA can affect the brain, behavior, and prostate gland in fetuses, infants, and children at current exposure levels. And a panel of independent experts convened by NIH, reporting in the Journal of Reproductive Toxicology in 2007, concluded that the levels of BPA in people are comparable to those that cause problems in animals and thus have "obvious potential to cause disease or dysfunction." In contrast, after reviewing the scientific literature, the FDA announced this past summer that the small amounts of BPA in food containers pose no health risk at all to children or adults.

The FDA has since been criticized for omitting key research and basing its position mostly on industry-sponsored studies. (Industry studies on BPA overwhelmingly find no risk, in contrast to government studies.) Even a subcommittee convened by the FDA disagreed with the FDA’s assessment. The FDA will continue to evaluate the effects of low-dose BPA, but it’s unlikely to change its position anytime soon—unlike Health Canada, which recently declared BPA a "toxic substance" and plans to ban it in infant bottles and limit exposure from infant formula cans. California and other states have been trying to ban polycarbonate with BPA, and a bill introduced in Congress would ban BPA from products used by young children and restrict its use in food containers nationwide. Meanwhile, more and more manufacturers and retailers, including Wal-Mart, are phasing BPA out of their products, in response to consumer demand.

Containing the risk

Though the final word on BPA is not yet in, limiting exposure makes sense, especially for young children and pregnant or breastfeeding women. Here’s how:

• Instead of polycarbonate plastic water bottles, baby bottles, or sippy cups, use glass, stainless steel, or aluminum bottles. The recycle number "7" in a triangle on the bottom often indicates that the plastic contains BPA—but not always. To know for sure, check with the manufacturer.

• Or look for other plastics. Nalgene, Camelback, and some other sports-bottle makers are switching to plastics, such as co-polyester, that do not contain BPA. It’s hoped that these substitutes are safer, though little is actually known about them. Increasingly, baby bottles and sippy cups are being made with other, presumably safer, plastics.

• If you do use polycarbonate bottles, don’t put hot liquids in them. Heating the plastic greatly increases the release of BPA into fluids subsequently stored in it. For instance, after being filled with boiling water, polycarbonate bottles released as much as 55 times more BPA, according to a 2008 study from the University of Cincinnati. Wash such bottles by hand with mild detergents and warm (not hot) water—never in the dishwasher. Keep them out of heat or sunlight (don’t store them in a car), and discard them if they discolor or develop spider cracks. Do not put them in the microwave.

• When possible, opt for food in jars or cartons instead of cans—or, better yet, fresh or frozen food. Acidic foods, such as tomatoes, cause more leaching of BPA from cans than other foods. Keep in mind, though, that the nutritional benefits of many canned foods (like fish, vegetables, and fruits) are definite, while the BPA risk is uncertain. If you are feeding a baby, powdered infant formula is a safer choice than canned liquid formula unless you know the cans are BPA-free (talk to your doctor before changing formula).

• Note that disposable plastic water bottles, as well as juice and soda bottles, are typically made from polyethylene (PETE, identified by the number "1" on the bottom), which has no BPA. They are considered safe for single use. The plastic may break down with repeated use, increasing the risk that other plastic chemicals will be released—but a better reason not to refill them over and over is that they can become contaminated with bacteria that are hard to clean off.

UC Berkeley Wellness Letter, February 2009