Some Plastics Linked to Risk for Diabetes and Heart Disease
< Sep. 17, 2008 > -- Bisphenol A (BPA), a chemical found in plastics that include baby bottles and packaging for food and beverages, may put people at risk for heart disease and type 2 diabetes, a new study concludes.
BPA is one of the world's highest production-volume chemicals, with more than two million metric tons produced worldwide in 2003. It is used in plastics in many consumer products and there has been an increase in demand of 6 percent to 10 percent annually.
"Widespread and continuous exposure to BPA, primarily through food but also through drinking water, dental sealants, dermal exposure, and inhalation of household dusts, is evident from the presence of detectable levels of BPA in more than 90 percent of the US population," say researchers in a new journal article.
The research, published this week in the Journal of the American Medical Association (JAMA), was released early to coincide with a public hearing the US Food and Drug Administration (FDA) is holding on the issue this week.
This is the first study of associations with BPA levels in a large population, and it explores "normal" levels of BPA exposure.
Evidence of adverse effects in animals has created concern over low-level chronic exposures in humans, but there is little data of sufficient statistical power to detect low-dose effects.
According to one expert, the study is suggestive, but not conclusive. "I am really torn here, because I really believe that BPA has some concerns, but this paper does not prove that," says Dr. Hugh S. Taylor, an associate professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at the Yale University School of Medicine.
"It's sort of classic guilt by association," Dr. Taylor says. "The correlations are there. There is more diabetes and more heart disease in people with more BPA, but people who are eating a lot of things out of cans and water bottles are going to have higher BPA in their urine, and they're probably not eating the healthiest diet, so you might expect them to have diabetes and heart disease."
In the study, led by Dr. David Melzer, of Peninsula Medical School, Exeter, in the United Kingdom, researchers looked at the association between BPA and heart disease and diabetes among 1,455 adults who participated in the 2003-2004 US National Health and Nutrition Examination Survey (NHANES).
Dr. Melzer's group found people with high levels of BPA were more likely to have heart disease, including heart attack, or diabetes. In fact, high levels of BPA increased the risk for these diseases by 39 percent, the researchers report.
In addition, higher BPA concentrations were associated with abnormal concentrations of three liver enzymes.
Health Conditions Correlate to BPA
"There are real problems with BPA use," Dr. Taylor says. "BPA is an estrogen-like endocrine disruptor. Clearly, from the animal data, there is reason to believe [that] BPA is hazardous to the fetus if taken during pregnancy. I think it's worth being cautious and at least trying to keep women who are pregnant away from BPA," he says. "With adult exposure, it is less certain that there is any adverse effect."
Dr. David O. Carpenter, director of the Institute for Health and the Environment at the University at Albany in New York, notes that he has shown that these very same diseases are associated with PCBs [polychlorinated biphenyls], dioxins, and chlorinated pesticides.
"I have a strong suspicion that BPA is doing exactly the same thing," he says. "I have been arguing that BPA should be banned for a long time just on the basis of its effect on endocrine systems. The industry reports that argue that it has no adverse effects are simply wrong," he says.
There is nobody who is not exposed to BPA, Dr. Carpenter adds. "The problem in our society is that we are all exposed to this mixture of chemicals, and which ones are responsible for disease is difficult to determine. This is really an important new observation," he says.
Not All Agree on the Dangers of BPA
The American Chemistry Council thinks the link between BPA and heart disease and diabetes is tenuous. "While scientific study continues, the public should be reassured by the FDA's own recent review of bisphenol A," says Tiffany Harrington, the council's director of public affairs.
BPA has been the subject of extensive scientific testing and government reviews worldwide, Harrington says. "These reviews have consistently concluded that human exposure levels to BPA are low and within the safe limits set by government authorities," she says.
"While properly designed and executed statistical studies on this and other compounds can bring valuable new insights with respect to human health, sometimes they do not, and sometimes they merely claim false associations that add little to and even confuse the body of science," Harrington adds.
Another expert, Dr. Rick Stahlhut, from the University of Rochester Medical Center in New York, agreed this study does not provide a causal link between BPA and heart disease and diabetes, but it is the first step toward discovering such a link. "The findings are intriguing, but they have to be validated," Dr. Stahlhut says.
Dr. Stahlhut says he expects the controversy to continue. "It's just like every other environmental exposure problem. We are always two decades behind. Ten to 20 years after the chemical is produced, suspicions start to rise. By then, it's a multi-billion-dollar industry, and now there are forces whose job it is to keep it going - and that is what is happening now," he says.
Until all the facts are known about BPA, Dr. Stahlhut recommends not exposing yourself to things you do not need. Do not take it for granted that because some "smiling guy on TV" says it is OK, it is, he says.
Always consult your physician for more information.
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More about BPA
According to the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences, BPA is a high production volume chemical used primarily in the production of polycarbonate plastics and epoxy resins.
Polycarbonate plastics have many applications including use in some food and drink packaging, e.g., water and infant bottles, compact discs, impact-resistant safety equipment, and medical devices. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some dental sealants and composites may also contribute to BPA exposure.
The primary source of exposure to BPA for most people is through the diet, states the NTP. While air, dust, and water are other possible sources of exposure, BPA in food and beverages accounts for the majority of daily human exposure.
BPA can leach into food from the protective internal epoxy resin lining of canned foods and from consumer products such as polycarbonate tableware, food storage containers, water bottles, and baby bottles. The degree to which BPA leaches from polycarbonate bottles into liquid may depend more on the temperature of the liquid or bottle, than the age of the container.
The NTP states that one reason people may be concerned about BPA is because human exposure to BPA is widespread. The 2003-2004 National Health and Nutrition Examination Survey (NHANES) conducted by the Centers for Disease Control and Prevention (CDC) found detectable levels of BPA in 93 percent of 2,517 urine samples from people six years and older. The CDC NHANES data are considered representative of exposures in the US.
Another reason for concern, especially for parents, may be because some animal studies report effects in fetuses and newborns exposed to BPA.
The NTP has “some concern“ for effects on the brain, behavior, and prostate gland in fetuses, infants, and children at current human exposures to BPA.
The NTP has “minimal concern“ for effects on the mammary gland and an earlier age for puberty for females, in fetuses, infants, and children at current human exposures to BPA.
More research is clearly needed to understand exactly how these findings relate to human health and development, but at this point the NTP cannot dismiss the possibility that the effects being seen in animals may occur in humans.
In the case of BPA, the NTP expressed “some concern” for potential exposures to the fetus, infants, and children.
There are insufficient data from studies in humans to reach a conclusion on reproductive or developmental hazards presented by current exposures to BPA, but there is limited evidence of developmental changes occurring in some animal studies at doses that are experienced by humans.
It is uncertain if similar changes would occur in humans, but the possibility of adverse health effects cannot be dismissed.
The NTP conclusions are based on the weight of scientific evidence, and integrate toxicity and exposure information.
Always consult your physician for more information.
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