Plastics and Your Health

Plastic products are often the source of urban legends. I remember when a friend told me that if I left my water bottle in the sun, it would leach dangerous chemicals into the liquid and cause certain reproductive harm. I was skeptical, but as a biochemistry major, not totally oblivious to the plethora of potentially hazardous chemicals in our plastic environment.

Plastics have reared their controversial head again, but this time it’s no urban legend. A group of Japanese researchers found that common plastic items, like baby bottles and soup bowls, could leach a hormone-mimicking compound into the consumables they hold.

The plastic in question is polycarbonate, a polymer made by stringing together molecules of bisphenol-A (BPA). BPA has estrogen-like activity and has been shown to increase the risk of cancer and cause developmental toxicity in laboratory animals. The Japanese researchers tested ten different polycarbonate baby bottles and found that, when heated, all leached BPA into the liquids they were holding. Food cans lined with polycarbonate were also found to leach BPA.

This study raises some serious concerns for parents and consumers worried about what they’re ingesting from their plastic containers. But to date, there have only been a handful of studies investigating the effects of BPA in humans. Almost all of the toxicology data has come from laboratory and animal studies. This has resulted in serious controversy between some scientists, who say that there is enough data to confirm that BPA is a threat to human health, and the plastic industry, who contends it is perfectly safe.

I spoke by phone with Dr. Frederick S. vom Saal, a researcher at the University of Missouri-Columbia who has been studying the low dosage effects of bisphenol-A in animals. He feels that we should be taking the matter of BPA leaching very seriously, especially for baby bottles.

“While the Japanese researchers used new bottles, older, worn bottles are most likely leaching more BPA and the older a bottle is, the increased rate of leaching.”

He also notes that although the amount of BPA an adult is getting from a bottle may be below the safety limit for their weight, exposure amounts must be adjusted for body weight. For a six to nine pound baby, the levels are the same as those that cause harm in animal studies.