Stanford Medicine Newsletter Updates For the Local Community

Health warnings on hard plastic

Summer 2008

Play eases the anxiety of Bernard Dannenberg's young patient.

Pediatrician Alan Greene, MD, takes a balanced approach to cutting back on plastic made with bisphenol A.

Bisphenol A—a chemical used to make hardened plastics—has been the subject of many recent news stories. Canada has banned baby bottles containing bisphenol A, and the U.S. National Toxicology Program has concluded that there is “some concern” that fetuses, infants and children may be harmed by small amounts of bisphenol A. In the early 1990s, researchers at the School of Medicine were the first to identify and call attention to the possible impact of bisphenol A on human health. Alan Greene, MD, an attending pediatrician at Lucile Packard Children’s Hospital, answers some common questions about this substance.

What is bisphenol A and what does it do? 

Bisphenol A, or BPA, is a synthetic, estrogen-like substance that is found in polycarbonate plastic and epoxy resins. Polycarbonate plastic is hard and clear, and is used in many reusable food and beverage containers, and epoxy resins are used to line metal cans.

Although there is no conclusive proof that ingesting small amounts of BPA can adversely affect human health, studies have implicated low levels of BPA exposure in aggression, hyperactivity, breast cancer and early puberty in lab animals.

How widespread is this problem?

BPA is estimated to be in more than 90 percent of baby bottles and in the liners of many cans of powdered and liquid formula. In fact, about 90 percent of people over the age of 6 have detectable levels of BPA in their urine.

Many major manufacturers and retailers are now starting to phase out its use. For example, Playtex and Nalgene have announced plans to drop the use of BPA-containing plastics and resins in their products, and major retailers like Wal-Mart are pulling these products from their shelves.

Should parents be worried? What can they do to reduce BPA exposure?

I think it’s more important to be educated than to be worried. In lab animals, BPA exposure slightly increases the risk of aggression, hyperactivity, cancer and early puberty—it doesn’t guarantee it will happen.

However, if it’s practical to replace BPA-containing bottles, that’s great. If not, then I’d avoid using worn bottles, which may be more likely to leak BPA, or heating breast milk or formula in them. I would also choose powdered over liquid canned formula. If liquid formula is used, the concentrated version is preferable to the ready-to-feed liquid. Finally, parents can look for formula cans that contain as little metal as possible.

Most of the concerns about BPA exposure seem focused on very young children. What about older children and adults?

Studies have indicated that protecting fetuses, infants and very young children should far-and-away be our biggest concern. A preliminary study in pregnant lab animals suggested that supplementation with folate reduced or eliminated the adverse health effects of BPA exposure in the offspring. In addition to providing our bodies with healthful micronutrients and vitamins, we can also exercise and eat right at every stage of life.

How can I identify BPA-containing containers, and what’s the most environmentally responsible way to dispose of them?

BPA-containing polycarbonate containers are often labeled on the bottom with recycling number 7. However, group 7 is a miscellaneous group that includes some really cool, environmentally friendly, potato- or rice-based materials. Call the manufacturer if you want to be certain.

You can recycle polycarbonate bottles or containers. Although BPA-containing polycarbonates are likely to be phased out of use for foods and beverages, the material still has many other useful applications in industrial safety equipment, park benches, etc.

More information on the scientific debate around the potential human health effects of bisphenol A can be found at the Web sites for the National Institute of Environmental Health Sciences ( and the National Toxicology Program (

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