Study: Avoiding Packaged, Canned Foods May Reduce Levels of the Chemical Bisphenol A
By Brenda Goodman
WebMD Health News
Latest Nutrition, Food & Recipes News
Reviewed by Laura J. Martin, MD
March 30, 2011 -- Families who gave up canned foods and food and beverages prepared and packaged using plastic containers saw their levels of a hormone-disrupting chemical fall by 66%, a new study shows. All it took was three days of eating only freshly prepared, organic foods.
The chemical bisphenol A (BPA) is found in many kinds of plastic food packaging, such as some water bottles, food storage containers, and sealing wrap. It is also used to line the inside of food cans.
BPA is an endocrine-disrupting chemical that has been associated with a host of health problems, including heart disease, diabetes, breast cancer, and infertility in adults, and attention deficit hyperactivity disorder (ADHD) in children.
"The study provides clear evidence that food packaging is the major source of people's exposure to bisphenol A and the phthalate known as DEHP," says study researcher Ruthann A. Rudel, MS, director of research for the Silent Spring Institute in Newton, Mass.
Phthalates are chemicals that make plastics strong, transparent, and clear.
"And that we found just by substituting fresh foods with limited packaging for three days, we reduced exposure levels in these participants by more than half," Rudel says.
The study is published in the journal Environmental Health Perspectives.
Avoiding Sources of BPA
For the study, researchers from Silent Spring and the Breast Cancer Fund, in San Francisco, recruited 20 people from five different families in the San Francisco area by posting on listserv sites.
The families were chosen based on answers to questions about how often they ate food from cans, drank water from plastic bottles, drank from an office water cooler, ate restaurant meals, or microwaved in plastic containers -- all sources of exposure to BPA and phthalates.
Monica Laurlund, 40, from Alamo, Calif., signed up her son, daughter, and husband because breast cancer runs on both sides of their family.
"To me, it seemed like an interesting way to find out if I'm being as healthy as I can be," she says.
Researchers took urine samples from each family member before, during, and after the study to check for levels of BPA and other chemicals found in plastics.
For three days, a caterer who had been specially coached to avoid preparing food exposed to chemicals from plastics delivered meals prepared from fresh and organic fruits, vegetables, grains, and meats.
The cooks were instructed to avoid contact with plastic utensils, and nonstick cookware and foods had to be stored in glass containers with BPA-free plastic lids. Researchers even told food preparers not to overfill the containers so the food wouldn't touch the plastic lid.
Microwaving in plastic was out; so was using coffee makers with plastic parts. Coffee drinkers got their morning coffee from French presses or ceramic drip models.
Participating families gave up water in plastic bottles in favor of stainless steel.
Eating out was also avoided since other studies have shown some restaurant meals to be high in BPA.
By the end of the study, urine tests showed the average BPA level dropped 66%, from 3.7 nanograms per milliliter (ng/mL) to 1.2 ng/mL. Levels of DEHP metabolites dropped by about half, from 57 ng/mL to 25 ng/ML.
People who started the study with the highest BPA levels saw even bigger reductions -- 76% for BPA and about 95% for DEHP metabolites.
"Especially after finding out the results, we have completely eliminated the plastics and the canned food," Laurland says. "It's really very simple things, and overall, those things are healthier for you anyway."
"What sold me on it is that I can easily take that toxic chemical out of my body and I don't have to worry about it," she says.
Why Worry About BPA?
Participants saw their levels drop, but science still doesn't know whether or not that matters.
"What the question is, is exactly how much risk, and to whom, from this kind of exposure? We're at a point where that's still emerging," Rudel says.
Still, the existing science has been compelling enough for Canada, which banned the use of BPA in baby bottles in 2008.
In the U.S., Eden Organic has started to sell foods in BPA-free cans. Several states have acted to limit the use of BPA, and similar bills are pending around the country.
The FDA is still studying that question, but so far, says that there's no need for families to change how they eat.
The food industry supports that statement.
"We agree with the U.S. Food and Drug Administration (FDA) that foods packaged in cans with epoxy linings that utilize BPA are safe, and that there is no need for consumers to change their consumption habits," the Grocery Manufacturers Association says in a statement. "That position is supported by the findings of numerous food safety agencies around the globe, such as the European Food Safety Authority (EFSA) in the EU, Germany, Japan, UK, Canada, and Australia-New Zealand, which have all repeatedly confirmed the safety of BPA and continue to reaffirm the safety of BPA, including at levels comparable to those found in the exposure survey published in EHP."
What Studies Show
Animal studies have shown an association with high and low levels of BPA with problems in neurodevelopment and reproductive development.
In 2008, the Journal of the American Medical Association published a study that found that adults with the highest levels of BPA in the study had more than twice the risk of getting diabetes as adults with the lowest levels.
But most studies such as these can only show associations; they can't prove that the chemicals are directly causing health problems.
Nira Ben-Jonathan, PhD, a professor of cell and cancer biology at the University of Cincinnati College of Medicine in Ohio, has studied what happens to cells when they are exposed to BPA in test tubes.
In one study, her team found that BPA exposure protected breast cancer cells from chemotherapy. In another, it made cells ignore a hormone that protects against the development of diabetes.
Even seeing those changes in cells, she said she had reservations about the message of this study.
"Interesting, but not as striking as one would expect," says Ben-Jonathan, who reviewed the study for WebMD. She said she found it suspicious that even after adhering to such a strict regimen that some chemical traces remained.
"That suggests to me that they're also getting BPA from nonfood sources," she says.
And if that's the case, she wonders, is it practical to advise people to make such big changes if it's not possible to really avoid the chemical?
"To tell people only to use organic food and they can reduce their BPA levels, I don't think so," she says. "It's so prevalent. ... It's not just food."
She said the greatest good could be accomplished if manufacturers made packaging changes.
"We are in an industrial world. We are surrounded by plastics. It's very difficult to avoid it. I think that the food industry and the chemical industry should really avoid using bisphenol A if they can find an alternative. Not all plastics can do this," she says.
The Can Manufacturers Institute says they are working on alternatives.
Advice for Consumers
Richard W. Stahlhut, MD, MPH, an environmental health researcher and preventive medicine specialist at the University of Rochester School of Medicine in New York, who has studied BPA exposure, says he tries to take "a Zen approach."
Stahlhut says when he's at home he tries to avoid plastics unless he needs them. If he can't avoid plastics, he tries not to worry too much about it.
"You can't be perfect, but you can be better," he says.
Stahlhut, who reviewed the study, says it appears to be well done and shows that you can make a big dent in BPA exposure by making straightforward changes to how you cook and eat.
And that those reductions are probably prudent, even though knowledge about BPA is still incomplete and probably will be for decades to come.
"Since it takes 10, 20, 30 years to find out, the best approach is that if you don't need an exposure, reduce it when you can. And when you can't, be Zen about it, because we don't know for sure that it's bad anyway."
In particular, experts said, it's probably smart to avoid heating food in plastic containers or covered in plastic wrap, since heating makes the chemicals in plastic break down more quickly and leach into food.
"Just say no. But be Zen about it," he says. "Because that's where we are in history. 100 years from now, we'll have new problems, but these are the ones we have now."
SOURCES: Rudel, R. Environmental Health Sciences, March 30, 2011.Ruthann A. Rudel, MS, director of research, Silent Spring Institute, Boston.Monica Laurlund, study participant, Alamo, Calif.Statement, Grocery Manufacturers Association.Lang, I. Journal of the American Medical Association, Sept. 16, 2008.FDA: "Update on Bisphenol A for Use in Food Contact Application."Stahlhut, R. Environmental Health Perspectives, May 2009.
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