Exposure to common chemical may be harmful

ByABC News
August 3, 2007, 6:00 PM

— -- Americans are exposed to far more of a controversial chemical than previously thought levels that likely surpass the government's current safety standard and which have been shown to cause harm in animals, according to a joint statement issued Thursday by 38 leading scientists.

While the chemical, bisphenol A, is hardly a household word, it is found in nearly every home and nearly everybody. Government tests have found bisphenol A used in plastic baby bottles, dental sealants and linings of metal cans in 95% of people studied.

While scientists haven't yet conducted definitive studies in people, animal tests have linked bisphenol A which acts like a hormone to problems such as obesity, early puberty, hyperactivity, and abnormal sexual behavior and reproductive cycles.

In their joint statement, however, scientists say they took a conservative approach, including only statements backed by many strong studies.

Scientists agreed that even very low doses cause profound effects on laboratory animals, particularly during pregnancy and infancy. The chemical can permanently rewire genetic programming before birth, potentially predisposing exposed animals to cancer. Bisphenol A also changes brain structure, body size and behavior in animals studied, scientists said.

Researchers issued their statement, published in Reproductive Toxicology, after reviewing about 700 animal studies.

The Environmental Protection Agency says bisphenol A is safe in doses of up to 50 micrograms per kilogram of body weight, per day. But a paper presented Thursday concludes that the high levels of bisphenol A in human blood and tissue suggest people are actually exposed to 10 times that amount.

One of the scientists, Retha Newbold of the National Institute of Environmental Health Sciences, says researchers need to find ways to measure whether people have been exposed to bisphenol A before or after birth, and if exposure increases their disease risk.