A new study from researchers at the Harvard School of Public Health (HSPH) has found that a group of volunteers who consumed a serving of canned food products each day for five days had a more than 1,000% increase in urinary bisphenol A (BPA) concentrations compared with when the same individuals consumed fresh food daily for five days. The study is one of the first to quantify BPA levels in humans after ingestion of canned foods.
The findings were published online November 22, 2011, in the Journal of the American Medical Association (JAMA) and will appear in the November 23/30 print issue.
In 2009, the North American Metal Packaging Alliance, a Washington-based trade group for can makers, said that “there is no readily available” alternative to BPA, which allows high temperature sterilization of canned food, preventing microbial contamination.
“Previous studies have linked elevated BPA levels with adverse health effects. The next step was to figure out how people are getting exposed to BPA. We've known for a while that drinking beverages that have been stored in certain hard plastics can increase the amount of BPA in your body. This study suggests that canned foods may be an even greater concern, especially given their wide use,” said Jenny Carwile, a doctoral student in the Department of Epidemiology at HSPH and lead author of the study.
Quickly lower your own BPA levels by making basic changes in what we eat and drink...
- Buy whole foods -- and carry them home in paper bags.
- Do not microwave in plastic -- even if it is labeled "microwave-safe"! Heat raises BPA levels in plastic, upping the health hazards. Instead, microwave food in glass or ceramic containers.
- Consider switching to a French press coffeemaker. Typical coffeemakers may contain traces of BPA and other toxins in the bin that holds the coffee filter and coffee. These grow more concentrated when heated.
- Kick the cans. Avoid canned foods except those that are in BPA-free cans, such as from Eden Foods, Vital Choice, Oregon's Choice and Trident Seafoods.
Simply put, just about anything you eat that comes out of a can -- from Campbell's Chicken Soup and SpaghettiOs to Diet Coke and BumbleBee Tuna -- contains BPA.
The exposure to BPA from canned food "is far more extensive" than from plastic bottles, said Shanna Swan, a professor and researcher at the University of Rochester in New York. "It's particularly concerning when it's lining infant formula cans."
- Watch out for the kids. Developing children are at even greater risk for harm from BPA. Use glass baby bottles or BPA-free plastic bottles. For older children, get stainless steel lunch boxes instead of plastic.
One scientist helping to lead the charge against BPA is Yale University physician, professor and researcher Hugh Taylor. His research has shown that the chemical alters the way genes react to estrogen, and could open the door for infants in utero to develop cancer much later in life.
"I tell my pregnant patients to avoid products containing it," he said. "Even a fleeting exposure in pregnancy can cause lasting damage."
The studies by Taylor are certainly eye-opening. They have shown that the chemical alters the way DNA operates, a process known as an epigenetic change.
Exposure to the endocrine-disrupting chemical BPA, used in the lining of metal food and beverage cans, has been shown to interfere with reproductive development in animals and has been linked with cardiovascular disease, diabetes, and obesity in humans. In addition to the lining of food and beverage cans, BPA is also found in polycarbonate bottles (identified by the recycling number 7) and dentistry composites and sealants.
The researchers, led by Carwile and Karin Michels, associate professor in the Department of Epidemiology, set out to quantify whether canned-soup consumption would increase urinary BPA concentrations relative to eating fresh soup.
They recruited student and staff volunteers from HSPH. One group consumed a 12-ounce serving of vegetarian canned soup each day for five days; another group consumed 12 ounces of vegetarian fresh soup (prepared without canned ingredients) daily for five days. After a two-day “washout” period, the groups reversed their assignments.
Urine samples of the 75 volunteers taken during the testing showed that consumption of a serving of canned soup daily was associated with a 1,221% increase in BPA compared to levels in urine collected after consumption of fresh soup.
The researchers note that the elevation in urinary BPA concentrations may be temporary and that further research is needed to quantify its duration.
“The magnitude of the rise in urinary BPA we observed after just one serving of soup was unexpected and may be of concern among individuals who regularly consume foods from cans or drink several canned beverages daily. It may be advisable for manufacturers to consider eliminating BPA from can linings,” said Michels, senior author of the study.