Although canned foods rarely make it to any "top ten" list of great-tasting or especially nutritious foods, the only real concern has ever been the loss of certain nutrients during the canning process and over time. All that changed when toxic chemicals were found in the food.
History
When a wide variety of commercially canned foods came on the market in the early twentieth century, housewives across America rejoiced at this quick and convenient way to feed their families. The prevailing message since that time has always been that as long as the can is sealed properly, and not damaged in any way when you buy it, the food inside is safe to eat. The high heat of processing sterilizes the can and destroys any bacteria or impurities in the food. At the same time, the metal can itself protects the food from further contamination. The only real concern about canned foods, it seemed, was the loss of some vitamins that occurred during processing.
Technology
Not so, says the Environmental Working Group (EWG), a consumer watchdog organization that tested canned foods from supermarkets across the United States and found high levels of the industrial chemical bisphenol A, better known as BPA, in half of them. BPA is a chemical used to make hard, clear plastic and epoxy resin and can be found in such everyday items as plastic food and drink containers. It can leach into foods and drinks. Turns out it may not be enough to simply avoid dented, leaking, or bulging cans of food, because even in perfect condition, the cans themselves may be toxic.
BPA is used in the production of some hard plastics and the plastic-like linings of many metal cans used to package foods and beverages. Since BPA leaches out of the plastic and into the contents of the can when exposed to heat, there is wide concern about its toxic effect. In 2008, the Centers for Disease Control issued a report showing that more than 92 percent of American people had low levels of BPA in their urine.
Research performed by members of the National Institutes of Health's National Toxicology Program (NTP) also found that the vast majority of Americans are exposed to BPA but not enough consistent research has been done on the effects of the chemical in humans. A relatively large body of animal studies has indicated, however, that BPA may be especially toxic to infants and children.
Health Risks
When pregnant animals are exposed to BPA, the chemical has negative effects on the development and behavior of their offspring. At high doses, studies found that BPA accelerated the age of puberty in male and female rodents and appeared toxic to the reproductive system. The NTP researchers found that adult animals are better able than fetuses, babies, and children to break down BPA and eliminate it before it does any harm.
What You Can Do
Nutritionists have always recommended fresh foods over convenience foods whenever possible, in order to get the most nutrition from your diet. Now there may be more reason to keep your use of canned foods to a minimum. The canned food industry is developing alternatives to BPA in products designed to contain food, and the Food and Drug Administration is in the process of establishing better regulation of these products. Until these efforts are in place, when you need the convenience of canned foods, look for products that are clearly labeled "BPA-free." They can be found in health food stores and supermarkets that carry a wide variety of food brands.
Sources:
Environmental Working Group
http://www.ewg.org/node/20936
National Institutes of Health/National Institute of Environmental Health Sciences. "Since You Asked: Bisphenol A (BPA)-NTP Conclusions." Web. 22 Feb 2011
http://www.niehs.nih.gov/news/media/questions/sya-bpa.cfm
U.S. Department of Health and Human Services/National Toxicology Program. "NTAP-CERHR Monograph on the Potential Human Reproductive and Developmental Effects of Bisphenol A" Sep 2008. Web. 22 Feb 2011
http://www.cerhr.niehs.nih.gov/evals/bisphenol/bisphenol.pdf
U.S. Food and Drug Administration. "Update on Bisphenol A for Use in Food Contact Applications: January 2010." 22 Mar 2010. Web. 22 Feb 2011
http://www.fda.gov/NewsEvents/PublicHealthFocus/ucm197739.htm
