The substance is bisphenol-a, or BPA, widely used in the making of the hard, clear and nearly unbreakable plastic called polycarbonate. Studies and tests show that trace amounts of BPA are leaching from polycarbonate containers into foods and liquids.
While most of the focus is on products for children, including clear plastic bottles and canned infant formula, the chemical is also used in food-storage containers, some clear plastic pitchers used for filtered water, refillable water bottles and the lining of soft-drink and food cans.
While there is debate about how much of a health worry BPA really is, retailers including Wal-Mart have said they are withdrawing baby products made with it. Nalgene, the maker of a popular sports bottle, and the baby-products maker Playtex have announced they will stop using it.
Here are answers to some common questions about BPA.
What is the evidence that BPA is harmful?
It all comes from animal studies. Rat pups exposed to BPA, through injection or food, showed changes in mammary and prostate tissue, suggesting a potential cancer risk. In some tests of female mice, exposure appeared to accelerate puberty.
A draft report from the National Toxicology Program, part of the Department of Health and Human Services, notes that there is no direct evidence that human exposure to BPA harms reproduction or infant development. “I don’t think there’s anything in this brief that should lead to alarm,” said Dr. Michael D. Shelby, director of the Center for the Evaluation of Risks to Human Reproduction, who oversaw the report. “It means we’ve got a limited amount of evidence from some studies that were done in laboratory animals.”
The main concern is the possible risk to infants and pregnant women, although Canada has begun a study to monitor BPA exposure among about 5,000 people to assess any danger to adults.
How much BPA are we exposed to?
BPA migrates into food from polycarbonate plastic bottles or the epoxy resin coatings that line canned food. The typical adult ingests an estimated 1 microgram of BPA for every kilogram (2.2 pounds) of body weight. Babies who use polycarbonate bottles and formula from cans get more, an estimated 10 micrograms per kilogram of body weight. A microgram represents a trace amount. Consider this: a single M&M is about a gram. If you cut it into 100,000 slices, one slice would equal about 10 micrograms.
The 2003-4 National Health and Nutrition Examination Survey by the Centers for Disease Control and Prevention found detectable levels of BPA in 93 percent of urine samples collected from more than 2,500 adults and children over six.
How do I know if the plastic containers in my home contain BPA?
Any product made of hard, clear plastic is probably made from polycarbonate unless the manufacturer specifically states that it’s BPA-free. One way to check is to look for the triangle stamp on or near the bottom: polycarbonate plastics should have the numeral 7 in the triangle, sometimes with the letters PC.
Unfortunately, 7 is a catchall “other” category for a variety of plastics. In my own kitchen, I found just one product with a 7 — plastic fruit cups my daughter takes to school. But the plastic is soft and pliable, so it is probably not made with BPA.
I also found refillable water bottles without a stamp. Because they are hard, shatterproof and clear, it’s reasonable to assume they are made from polycarbonate.
What about canned food and drinks?
While much of the focus is on plastic bottles, most human exposure occurs through the lining of canned foods. Canned beverages appear to contain less of the chemical than canned foods like soup, pasta, fruits and vegetables, which are often processed at high temperatures. Virtually every canned product, even those labeled organic, has a liner with BPA. One brand, Eden Organic Baked Beans, says it uses a BPA-free can.
How do I lower my exposure?
Switch to frozen or fresh vegetables. Use glass, porcelain and stainless-steel containers, particularly for hot foods and liquids. If you don’t want to use a glass baby bottle, several companies, including the popular brand Born Free, now sell BPA-free baby bottles and sippy cups. For formula-fed babies, you can switch to powdered formula rather than liquid.
Although many plastic products claim to be microwave safe, some scientists warn against putting any plastic in the microwave. “There is such a wide variety now, from disposable containers to actual Tupperware,” says Dr. Anila Jacob, a senior scientist for the Environmental Working Group, a Washington-based advocacy group. “I don’t know of anyone who has done definitive testing of all these different types of plastic containers to see what is leaching into food.
Source: Tara Parker-Pope, New York Times
