A Common Plastic Comes Under Scrutiny

Polycarbonate plastic is long-lasting, impact-resistant, and clear. This makes it a perfect material for baby bottles, refillable water bottles, sippy cups, and many other food and drink containers. It is also found in eyeglass lenses, compact discs, dental sealants, and plastic dinnerware. And, as a resin, it forms the protective lining for metal food and drink cans.

But research has raised concerns about the health effects of a chemical used in the manufacture of polycarbonate — bisphenol A (BPA). Some studies have found that BPA can leak trace amounts from polycarbonate containers and resin linings into foods and drinks. In tests on lab animals, BPA appears to copy or disturb the hormone estrogen and affect the reproductive system. This could possibly raise the risk for cancer.

Babies and young children are at greatest risk because they eat and drink more than adults on a pound-for-pound basis. In this way, they have a greater exposure to BPA, says the National Institute of Environmental Health Sciences (NIEHS). Because of this risk, in 2012 the FDA banned the use of BPA in baby bottles and sippy cups to reduce human exposure to BPA.

Polycarbonate plastic is found almost everywhere in modern life. And BPA is one of the highest-volume chemicals produced worldwide. Polycarbonate plastic has proved a handy substitute for glass and ceramic containers. Glass and ceramic can break or can be hard to clean. Polycarbonate plastic bottles can be sterilized easily and don't soak up odors. As a resin, polycarbonate lines the insides of most canned foods. This includes baby formula.

Other types of plastics are also used as food and drink containers. You can tell one plastic from another by the recycling triangle stamped on the container (usually on the bottom). Polycarbonate usually containers carry a No. 7.

In a 2003-2004 health survey, the CDC made a surprising discovery. It found BPA in the urine of nearly 93% of the more than 2,500 people tested. The survey evaluated children 6 years of age and older, teens, and adults. Females had significantly higher levels of BPA than did males. Children had the highest levels.

Most people are exposed to BPA through foods and drinks, according to the NIEHS. It is also found in air, dust, and ground and surface water.

BPA ends up in foods and drinks because it leaks from containers and can linings. Certain foods, as well as heat, appear to speed up this leaking, the NIEHS says.

A number of studies suggest a link between BPA exposure at a young age and certain health problems. Animal studies have shown that BPA at levels typical in the environment acts like estrogen on breast, ovarian, and prostate tissue. Some researchers point to a possible connection between BPA and obesity, diabetes, and heart disease.

Based on a review of the published studies, the NIEHS says it has "some concern" about the health effects of BPA on fetuses, infants, and young children. BPA does not appear to cause birth defects. But it may cause neural and behavioral effects, it says. Adults who are not exposed to BPA at work don't seem to be at risk for reproductive system problems.

The study results are based on animal research. This may be hard to apply to people, the NIEHS says. But the possibility that BPA may change human development must be considered. More research is needed to measure the effects of exposure on human health.

While scientists debate the issue, you can take steps to reduce your family's exposure to BPA.

Here are suggestions from the NIEHS:

• Don't use polycarbonate containers that contain BPA. They usually have a No. 7, and sometimes a No. 3, stamped on the bottom.
• If you do use polycarbonate containers, don't put them in the microwave. When heated, the plastic may break down over time.
• When possible, use fresh or frozen foods instead of canned foods.
• Choose glass, porcelain, and stainless steel containers instead of plastic. This is especially important for foods or drinks that are hot.
• Use baby bottles and sippy cups that aren't made with BPA. Bottles or cups made before 2012 may contain BPA.

Please consult your doctor with any questions or concerns you may have about this condition.