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Water bottles made with the controversial carbonate plastic bisphenol A, or BPA.
Where is BPA found?
The National Toxicology Program says the main source of human exposure to bisphenol A, or BPA, is the tiny amounts that leach from Nalgene-type polycarbonate water bottles and from metal cans — that could include canned vegetables and fruits — lined with an epoxy resin that contains BPA. The chemical is also found in baby bottles, tableware and food storage containers.
Does BPA cause health problems?
Studies about the effects of BPA have been conflicting. Some animal studies have suggested a link between BPA and effects on the brain, behavior and the prostate gland — and raised concerns about the effects of exposure on the developing fetus and young children. But there are no conclusive studies linking BPA to human health problems.
It's also unclear what determines how much leaching occurs. It may depend on the temperature of the liquid or bottle or how the plastic is reused.
What should I avoid?
To minimize exposure to BPA, the National Toxicology Program recommends that people avoid microwaving plastic food containers or washing them in the dishwasher with harsh detergents. Repeated exposure to high temperatures and harsh cleaning agents can deteriorate the plastic and release BPA.
Additionally, some sources, such as NTP, have advised consumers to avoid hard, clear plastic containers with the No. 7 on the bottom. While the chemical industry maintains that plastic bottles contain little BPA and leach trace amounts too low to be harmful to humans, some companies have voluntarily elected to sell BPA-free products. Nalgene sells BPA-free water bottles, and retailers such as Toys R Us and Wal-Mart offer baby bottles and other children's products that are BPA-free.
— Kathleen Masterson
A new study could change the debate over the safety of bisphenol A, a compound found in many plastics.
It suggests that there is an association between higher exposures to BPA and the development of heart disease and diabetes.
The study, appearing in this week's Journal of the American Medical Association, finds that adults with the highest levels of BPA in their urine were more than twice as likely to report having diabetes or heart disease — compared with adults with the lowest levels of the chemical in their urine.
Though it brings up new possible human health risks, the study, which is being discussed today at a meeting of the Food and Drug Administration's science advisory board, offers no conclusive answers. It does not prove a cause and effect between use of plastic food containers and the development of diabetes or heart disease.
"We don't have a lot of evidence in people about the effects of BPA. This is one of the first studies, and it finds something disturbing. It's suggesting there may be harm in adults, which we didn't really believe based on the animal studies," says David Schardt, a staff scientist with the Center for Science in the Public Interest.
The study uses data drawn from the National Health and Nutrition Examination Survey — a survey conducted by the federal government — isolating a group of adults between the ages of 18 and 74 who are representative of the U.S. population at large. The survey asked a series of health-related questions, and participants provided a urine sample. Researchers then tested the urine samples for a range of compounds, including bisphenol A.
"We were interested in diseases of the 50 and older age group and that's originally what we looked at. And then we realized that these associations went into the larger adult populations. And it just turned out that these signals were exceptionally strong and exceptionally robust," says David Melzer, the study's director and professor of epidemiology and public health at Peninsula Medical School in England.
The researchers adjusted for things like weight and smoking, but the association between high BPA urine levels and likelihood of having the diseases held.
"If you could take two individuals with same sex, race, age, ethnicity, body build, cigarette smoking status, and had one individual that [had] low levels of BPA and one individual that had high levels of BPA, the individual with high levels of BPA would be more likely to also report being a diabetic or having cardiovascular disease history," says Ken Portier, a statistician with the American Cancer Society and an expert at interpreting these kinds of snapshot-in-time studies.
Portier says the findings are certainly strong enough to merit follow-up, and the next step might be to look at another group of the survey participants and see if the associations hold up.
Melzer is scheduled to discuss his findings today at a Food and Drug Administration meeting where the agency has issued a draft proposal on bisphenol A.
At this time, the FDA finds the current level of exposure to BPA through food containers safe.