By Lisa Wade McCormick
January 13, 2010
Another study is raising concerns about human exposure to bisphenol A (BPA) this time finding a significant link between the chemical and cardiovascular disease.
The study released late Tuesday night by the Peninsula Medical School and University of Exeter found that higher exposure to BPA -- a chemical used in plastic water bottles, baby bottles, and food can linings -- was consistently linked to heart disease in American adults.
This new study, Association of Urinary Bisphenol A Concentration with Heart Disease, also confirms earlier findings by the United Kingdom researchers that showed a link between BPA exposure and heart disease. Those findings appeared in the 2008 Journal of the American Medical Association (JAMA). British researchers said this new study rules out the possibility that their previous findings were a statistical blip.
From two completely separate samples of the US adult population, we conclude that higher BPA exposure, reflected in higher urinary concentrations of BPA, is consistently associated with reported heart disease in the general adult population of the US, according to the studys authors. Their analysis is now published in the online journal PLoS ONE.
Despite these latest findings, researchers are quick to point out their study isnt conclusive.
We can't say conclusively from our data that having high BPA concentrations causes heart disease, Professor Tamara S. Galloway, one of the study's authors, told ConsumerAffairs.com. It could be the other way around -- that something about having heart disease changes the way that a person metabolizes the chemical. Or alternatively, there could be another factor, say a lifestyle factor, that is common to both groups.
She added: This is what's called a cross-sectional study. That means that it looks at what is happening at one particular time. In the samples we studied, there was a statistical association between having a higher concentration of bisphenol A metabolites in your urine and prevalence of heart disease.
An industry group that represents top chemistry companies downplayed the study, saying it didnt establish a cause-and-effect relationship between BPA exposure and heart disease. The American Chemistry Council also said BPA is safe in food and beverage packaging.
The U.S. Food and Drug Administration (FDA) agrees that products containing BPA are safe. But the agency is conducting a risk assessment of the chemical.
These latest findings add to the growing number of studies that have linked BPA exposure to serious health problems, including Type 2 diabetes, liver-enzyme abnormalities, prostate and breast cancer, early onset of puberty, and obesity.
A 2009 study uncovered a link between BPA exposure in early pregnancy and aggression and hyperactivity in the women's two-year-old daughters.
Previous animal studies have also found that prenatal BPA exposure is linked to impaired learning, aggression, and alterations in addictive behavior in rodents.
Manufacturers have used BPA for years to make plastics and resins. More than six millions tons of the chemical are produced each year and used in everything from plastic baby bottles to compact disks. Scientists say most people are exposed to BPA through their diets, specifically from food and beverage containers made with the chemical.
Found in urine
Researchers at the Harvard School of Public Health recently found that BPA leaches from polycarbonate bottles -- those hard, plastic drinking and baby bottles -- and winds up in the urine of people who drink from them. Polycarbonate is a shatter-proof plastic made with BPA.
Young children can also be exposed to the chemical if they chew on products may with BPA.
A recent analysis by The Centers for Disease Control and Prevention (CDC) illustrated the widespread exposure of BPA in humans. The study found BPA in the urine of more than 90 percent of the people tested. In this latest study, British researchers analyzed data collected in 2005-2006 from the U.S. National Health and Nutrition Examination Survey (NHANES).
The 720 men and 773 women in the study -- ages 18-74 -- provided urine samples that were tested for BPA. In the 2008 study, researchers examined NHANES data from 2003-2004. Scientists who analyzed that information -- the worlds first large-scale data on urinary BPA concentrations -- found a link between BPA and coronary heart disease, diabetes, and raised liver enzymes.
Researchers wanted to see if those associations were present in the new NHANES data.
With the kind of cross-sectional study that we performed, one of the important things is to be able to replicate the findings, for example, to show that the association between BPA exposure and health effects is present in another, separate population, Professor Galloway told us. This makes it much less likely that the findings are the result of chance. That's what this study set out to do.
Galloway and her colleagues confirmed the link between BPA exposure and heart disease in the new data studied, but found a weaker association with Type 2 diabetes.
But BPA is still associated with this condition when we combine all the available data, researchers said, adding associations with some liver enzymes were also found.
Researchers noted one difference with the new data analyzed the urinary BPA concentrations were one-third lower than those in the 2008 study. We dont have data on the reasons for this change. Professor Galloway said she and her colleagues arent calling for legislative leaders to change laws governing the use of BPA because of their latest findings.
I'm sure that policy makers will view this study alongside all of the existing knowledge on the safety of bisphenol A before making any decisions about its safety, she said.
What about current strategies used to prevent heart disease and diabetes, like losing weight and quitting smoking? What impact will the study have on those recommendations?
There is nothing in our study to change the normal health advice to people on reducing their risks of heart disease or diabetes, Professor Galloway said. But the study, she said, does indicate that more research is needed to determine the health effects on humans from BPA exposure.
More study needed
As researchers we now need to investigate what causes these health risk associations in more detail and to clarify whether they are caused by BPA itself or by some other factor linked to BPA exposure, Professor Galloway said. The risks associated with exposure to BPA may be small, but they are relevant to very large numbers of people. This information is important because it provides a great opportunity for intervention to reduce the risks.
The American Chemistry Council rebuffed these latest findings, saying researchers made an unscientific leap.
Studies of this type are very limited in what they tell us about potential impacts on human health, said Steven G. Hentges, Ph.D., of the American Chemistry Councils Polycarbonate/BPA Global Group. While they can provide helpful information on where to focus future research, by themselves they cannot and should not be used to demonstrate that a particular chemical can cause a particular effect.
The public should be confident that BPA is one of the most studied chemicals, he added. Regulatory bodies from around the world have recently completed scientific evaluations and found BPA safe in food-contact products, including canned foods and beverages.
The FDA -- for now also says BPA is safe. But the agency is reviewing previous studies on human exposure to the chemical.
FDA officials, however, missed their promised 2009 deadline to let the public know if the thousands of products made with BPA posed any health risks to humans.
At this time, FDA is not recommending that anyone discontinue using products that contain BPA while we continue our risk assessment process, the agency states on its Web site. However, concerned consumers should know that several alternatives to polycarbonate baby bottles exist, including glass baby bottles.
The FDA adds: Based on our ongoing review, we believe there is a large body of evidence that indicates that FDA-regulated products containing BPA currently on the market are safe and that exposure levels to BPA from food contact materials, including for infants and children, are below those that may cause health effects.
But several companies that make plastic baby bottles have already stopped using BPA in their products because of scientific studies that found possible links between the chemical and adverse heath effects.
In 2009, six companies announced they will no longer use polycarbonate plastic bottles for baby products in the U.S.: Avent America, Inc; Disney First Years; Dr. Brown; Evenflo Co.; Gerber; and Playtex Products, Inc. The retail giant Wal-Mart also stopped stop selling baby bottles that contain BPA.
Several states have enacted legislation to ban or limit the use of BPA in consumer products, too. Canada also banned the import and use of BPA in baby feeding bottles, sippy cups, and pacifiers.
But there are currently no federal regulations regarding the use of BPA in U.S. products, researchers say.
What to do?
What steps can consumers take to reduce their exposure to BPA?
The National Institute of Environmental Health Studies recommends the following:
• Use BPA-free baby bottles;
• Dont microwave food containers made with polycarbonate plastic. Polycarbonate may break down from over-use at high temperatures;
• Reduce the use of canned foods;
• Use food containers made of glass, porcelain, or stainless steel whenever possible, especially for hot foods and liquids;
• Avoid buying plastic products made with BPA. Those products may have the recycling number 7 on the bottom.
BPA Linked to Increased Risk of Heart Disease...