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A Common Plastic Comes Under Scrutiny

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A Common Plastic Comes Under Scrutiny

Polycarbonate plastic is durable, impact-resistant, and clear, making it an ideal material for baby bottles, refillable water bottles, sippy cups, and many other food and beverage 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 beverage cans.

But recent research has raised concerns over the health effects of a chemical used in the manufacture of polycarbonate bisphenol A (BPA). Some studies have found that BPA can leach in trace amounts from polycarbonate containers and resin linings into foods and beverages. In tests on laboratory animals, BPA appears to mimic or disrupt the hormone estrogen and thus affect the reproductive system, possibly raising the risk for cancer.

Infants and young children are at greatest risk because they eat and drink more than adults on a pound-for-pound basis, and so have greater exposure to BPA, says the National Institute of Environmental Health Sciences (NIEHS). Because of this risk, Canadian health officials have banned the sale of polycarbonate baby bottles beginning in June 2008 and may require that infant formula containers use some other lining than polycarbonate resin. Canada has also begun monitoring BPA exposure in 5,000 adults to see what long-term effects the chemical may have. In 2009, the six largest manufacturers of baby bottles vowed to stop selling polycarbonate versions in the United States. 

Is BPA use common?

Polycarbonate plastic is found virtually everywhere in modern life, and BPA is one of the highest-volume chemicals produced worldwide. Polycarbonate plastic has proved a versatile alternative to glass and ceramic containers, which break or can be difficult to clean. Polycarbonate plastic bottles can be sterilized easily and don't absorb odors. As a resin, polycarbonate lines the insides of most canned foods, including baby formula.

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

What's the problem?

In a 2003-04 health survey, the Centers for Disease Control and Prevention made a surprising discovery: It found BPA in the urine of nearly 93 percent 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, and children had the highest levels.

Most people are exposed to BPA through foods and beverages, according to the NIEHS, although it's also found in air, dust, and ground and surface water. A typical adult takes in daily about 1 microgram (mcg) of BPA for every 2.2 pounds of body weight, while infants who are fed with polycarbonate bottles and canned formula may take in 10 times that amount for the same weight.

BPA ends up in foods and beverages because it leaches from containers and can linings. Certain foods, as well as heat, appear to speed up the leaching, the NIEHS says.

A number of studies suggest a link between BPA exposure at a young age and certain health problems. According to a report published in 2008 in the journal Environmental Health Perspectives, BPA at levels typical in the environment has an estrogen-like effect on breast, ovarian, and prostate tissue, and may also affect the thyroid. Some researchers point to a possible connection between BPA and ADHD, obesity, and diabetes.

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. BPA exposure in adults, however, does not appear to have an effect on the reproductive system.

Although the study results are based on animal research, which may be difficult to apply to people, the NIEHS says, the possibility that BPA may alter human development must be considered. More research is needed to assess the human health effects of exposure.

What can you do to lower BPA exposure?

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

Here are suggestions from the NIEHS: 

  • Avoid polycarbonate containers that contain BPA. They usually have a No. 7 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, particularly for foods or beverages that are hot.

  • Use baby bottles and sippy cups that are BPA-free.

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