Bisphenol A, also called BPA, is used in polycarbonate plastic -- hard plastic used in products including some baby bottles and refillable water bottles -- and in epoxy resins, which line some canned goods and are also in dental composites and sealants. Bisphenol A isn't found in softer plastics, such as single-serving water bottles.
The study doesn't prove that bisphenol A caused those problems. But the findings are "disturbing," says David Schardt, MS, senior nutritionist of the Center for Science in the Public Interest. The plastics industry, on the other hand, stands by bisphenol A's safety.
The findings, published in The Journal of the American Medical Association, were presented today at an FDA public hearing on bisphenol A. Here's what you need to know about the new bisphenol A study.
Bisphenol A Study Findings
Most bisphenol A studies have been done in lab tests on rodents. The new study is all about humans.
The researchers checked government data on heart disease, diabetes, and bisphenol A in 1,455 U.S. adults aged 18-74.
As part of a national health study done in 2003-2004, participants provided urine samples and were asked if they had ever been diagnosed with cardiovascular disease -- heart attack, coronary heart disease, or chest pain (angina) -- or diabetes.
People with the highest urinary levels of bisphenol A were more than twice as likely to report ever being diagnosed with cardiovascular disease or diabetes, compared to people with the lowest urinary levels of bisphenol A. High urinary levels of bisphenol A were also linked to abnormal concentrations of liver enzymes.
To put the heart disease and diabetes findings in perspective, those conditions were relatively rare: 79 people reported a history of heart disease and 136 reported a history of diabetes.
The study didn't directly test bisphenol A to see if caused health problems, so it doesn't prove that bisphenol A was to blame.
Still, the results held regardless of factors including age, sex, race, smoking, and BMI (body mass index). But the researchers didn't adjust for all possible influences, including family history of heart disease or diabetes.
David Melzer, MB, PHD, worked on the new bisphenol A study. He's a professor of epidemiology and public health at Peninsula Medical School at England's University of Exeter.
People with high urinary levels of bisphenol A probably weren't exposed to extreme levels of bisphenol A, according to Melzer.
"It looks as if what people were exposed to was way lower than what is considered the safe level at the moment," Melzer tells WebMD. But he adds that it's not clear where their bisphenol A came from.
Melzer's team isn't calling for a ban on bisphenol A, and they're not telling people to ditch their canned goods or polycarbonate plastic products. But they do want to see more research done.
Melzer says future research should check the study's findings in other groups of people, track healthy people to see if those with high levels of bisphenol A develop health problems later on, and identify the leading sources of bisphenol A exposure.
"Which are the main products, which types of food, what particular packaging is actually delivering these levels into people?" asks Melzer. "It would be much easier to understand what to do if we knew where it was coming from, especially in those people who seem to have marginally higher levels."
For now, Melzer warns against jumping to conclusions. "Please don't read too much into this first study; it's limited in various ways," he says.
Melzer also notes that a healthy lifestyle -- regardless of bisphenol A -- is still a crucial part of preventing heart disease and diabetes. "Healthy eating and exercise and so on are still very important," says Melzer.
Bisphenol A Critic's View
Fred vom Saal, PhD, is a bisphenol A researcher who co-wrote an editorial published with the study.
"It is important to point out that it is a snapshot study -- one measurement of bisphenol A and in relation to health status," vom Saal tells WebMD. But he says the results show "such a strong relationship" between high urinary bisphenol A levels and health effects.
He explains that bisphenol A acts like estrogen, pushing up insulin levels, which may lead to insulin resistance and diabetes. "That's exactly what it does in animals," says vom Saal, who testified at today's FDA meeting and is critical of the FDA's stance that bisphenol A is safe at typical exposure levels from food and drink.
"The FDA says there has to be a reasonable certainty of safety in order to use these products. I look at the entire literature and I say there is a very reasonable certainty of harm," says vom Saal.
An FDA spokesperson wasn't immediately available to comment on that. The FDA recently issued a draft report on the safety of bisphenol A in food contact items (food and drink packaging). That draft report deemed bisphenol A food and drink containers safe for typical use. European regulators recently took a similar stance.
But another government agency, the National Toxicology Program, doesn't rule out all risk from bisphenol A. In a separate report the NTP notes "some concern" for effects on the brain, prostate gland, and on behavior in fetuses, infants, and children.
WebMD contacted the American Chemistry Council (a trade group for the plastics industry) and the North American Metal Packaging Alliance (a trade group for the canned goods industry) for their comments on the study.
The American Chemistry Council replied by email with a statement underscoring the limitations mentioned in the study. Because of those limitations, "this new study cannot support a conclusion that bisphenol A causes any disease," Steven G. Hentges, PhD, of the American Chemistry Council's Polycarbonate/BPA Global Group, states in a news release. "The weight of scientific evidence continues to support the conclusion of governments worldwide that bisphenol A is not a significant health concern at the trace levels present in some consumer products," Hentges states.
The council doesn't totally dismiss the study, but it sees the study as being "primarily useful for generating hypotheses that can be tested with more appropriate experiments or analyses," states the council's news release.
The North American Metal Packaging Alliance (NAMPA) also emailed a statement, which points out that study participants only provided one urine sample, and that the body "quickly and efficiently" eliminates bisphenol A through urine. "To suggest that BPA concentrations measured at a single point in time during the process of elimination from the body correlate in any way directly with serious chronic disorders is entirely unsupported and an unsubstantiated scientific leap," states NAMPA, adding that "while the study raises interesting questions, it provides no scientifically defensible answers" and requires further research.
The CSPI's Schardt notes that in lab tests on animals, the biggest risks appeared to be to young animals, but Melzer's team found risks in adults, including people too old to have been exposed to bisphenol A as kids.
"So that's a mystery: If they were being harmed by BPA, when did this happen?" asks Schardt.
Like Melzer, Schardt calls for more research.
"One can't expect the government to make a 180-degree turn based on one study like this," says Schardt. "It underscores the need for more research on BPA. We need to get to the bottom of this, we need to find out what, if anything, BPA is doing to us."
Schardt says there's not enough evidence yet to call for a ban on bisphenol A, but he suggests that parents may want to consider using bisphenol A-free containers for babies and kids.
As for adults, "you don't really want to make drastic changes in your lifestyle based on one study," says Schardt. "Of course, people are free to try to avoid BPA but again, they're not going to avoid it entirely because it's just everywhere."