Container chemical causes controversy

Bisphenol A exposure linked to cardiovascular disease, diabetes, according to study

By: Deborah L. Shelton

Posted: 9/22/08

CHICAGO (MCT) - The debate over the safety of a chemical ubiquitous in the lives of Americans took center stage at a scientific hearing of the U.S. Food and Drug Administration on Tuesday as federal officials, scientists and health advocates gave vastly different assessments of the effects of exposure to bisphenol A.

Bisphenol A, commonly known as BPA, is used extensively in epoxy resins lining food and beverage containers and in polycarbonate plastics used to make countless consumer products including baby bottles and sippy cups. The chemical also has been found in drinking water, dental sealants and even household dust.

Adding to a growing sense of unease about the chemical's potential effects, a study was released before the hearing that linked exposure to bisphenol A with cardiovascular disease, type 2 diabetes and liver-enzyme abnormalities in adults.

Researchers said the study, in Wednesday's Journal of the American Medical Association, offered the first scientific evidence that adults with higher levels of BPA in their bodies were more likely to develop such diseases. This month the federal National Toxicology Program reported the chemical may affect the development of the brains and prostate glands of fetuses and young children.

Pressure has been growing for more government and corporate action on BPA, in part because the chemical is so common that it is difficult for consumers to avoid it.

Some state and federal lawmakers have sought to ban BPA in children's products, and some companies have decided not to produce or sell BPA products. Wal-Mart is phasing out sales of baby bottles containing BPA from its U.S. stores next year, and Nalgene is removing BPA from its popular water bottles.

At Tuesday's hearing on BPA in products that make contact with food, the FDA defended a draft assessment it issued last month declaring that FDA-regulated products currently on the market that contain BPA are safe.

"Right now, our tentative conclusion is that it's safe, so we're not recommending any change in habits," said Laura Tarantino, head of the FDA's Office of Food Additive Safety. The agency said more research was needed.

For the study released Wednesday, Dr. David Melzer and colleagues from the Peninsula Medical School in Exeter, England, divided a representative sample of 1,455 U.S. residents' ages 18 to 74 into quartiles based on BPA concentrations in their urine. The BPA data came from a 2003-2004 survey conducted by the Centers for Disease Control and Prevention.

The researchers found that people in the group with the highest concentration of BPA had almost three times the odds of cardiovascular disease as did those in the lowest quartile, even when factors such as race, income and education levels were accounted for. That group had a 2.4 times higher risk of diabetes.

Higher BPA levels also were associated with clinically abnormal concentrations of three liver enzymes. Researchers did not find a link to any other health problems, including cancer or respiratory disease.

Though previous research in animals had linked BPA to diabetes and liver damage, Melzer said the new finding on human heart disease was unexpected.

Steven G. Hentges, executive director of the Polycarbonate/BPA Global Group of the American Chemistry Council, an industry trade group, noted several limitations of the research.

"Urinary concentrations tell you the exposure over the last 24 hours, but heart disease and diabetes do not occur overnight," he said. "Bisphenol A would have to be measured over the time period when heart disease or diabetes is actually occurring, so that's a major limitation of the study."

Hentges also said the study showed that people were being exposed to very low levels of the chemical, "levels that are far below scientific-based safety standards established by government agencies."

Small amounts of BPA can leach into the contents of food or drinks from some types of plastic containers and the linings of cans. The chemical is excreted in urine, making urinary tests the best available measure of recent exposure, the researchers said.

The authors cautioned that further research is needed to confirm their findings.

"From this one study we can say that the effects of BPA in humans need to be examined more closely," said Melzer, a professor of epidemiology and public health. "Until we are able to repeat these results and clarify that the effects are definitely due to BPA itself, we cannot say for certain that BPA causes disease in humans."

Frederick vom Saal, a professor of biology at University of Missouri-Columbia, said the findings were "absolutely no surprise" to scientists who have studied the chemical, which he described as "one of the largest food contact items in existence." He served on a scientific consensus panel of 38 experts that recently reviewed 700 studies of BPA and concluded that it had a high probability of causing harm.

"If a study comes out of nowhere on a subject that has never been studied, you might say, 'How in God's name can bisphenol A possibly be related to diabetes?'" said vom Saal, who wrote an editorial that accompanied the JAMA study. "But we have a large literature of animal studies that explains the molecular details."

Dr. Anila Jacob, senior scientist for the Environmental Working Group, a Washington-based research and public health watchdog organization, said the study suggested BPA might play a more significant part in chronic diseases than had been thought.

"We don't know causality (in this study), but associations are important in public health," Jacob said. "The first studies of tobacco found associations between smoking and lung cancer. These types of large epidemiologic studies are important in pointing us in the right direction."

Some scientists are urging the FDA to declare the chemical toxic and ban it from products that come into contact with food and drinks.

"We have always been concerned about infants and children because we know they have higher exposures compared to adults and we also know they are more vulnerable because their brains are developing and their organ systems are maturing," Jacob said. "But we believe there is reason for concern for everyone. Until the FDA starts to recognize the toxicity of this chemical, individuals are forced to find ways to reduce exposure to this chemical on their own."

The study was funded by Peninsula Medical School, and the Division of Environmental Health Laboratory Sciences at the CDC's National Center for Environmental Health did the analysis.