BPA Found in Aluminum Cans, as well as Plastics

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BPA Lurks in Canned Soups and Drinks
By ANAHAD O'CONNOR of The New York Times
November 22, 2011

Harvard researchers have discovered that people who ate one serving of canned food daily over the course of five days had more than a tenfold increase of levels of bisphenol-A, or BPA, a substance that lines most food and drink cans. Most of the research on BPA, a so-called endocrine disruptor that can mimic the body’s hormones, has focused on its use in plastic bottles. It has been linked in some studies to a higher risk of cancer, heart disease, diabetes and obesity, and health officials in the United States have come under increasing pressure to regulate it.

The new study, which was published Tuesday (November 22nd, 2011) in The Journal of the American Medical Association, is the first to measure the amounts that are ingested when people eat food that comes directly out of a can, in this case soup. The spike in BPA levels that the researchers recorded is one of the highest seen in any study. “We cannot say from our research what the consequences are,” said Karin Michels, an associate professor of epidemiology at Harvard Medical School and an author of the study. “But the very high levels that we found are very surprising. We would have never expected a thousand-percent increase in their levels of BPA.”

As part of the study, Dr. Michels and her colleagues recruited a group of 75 staff members and students at the Harvard School of Public Health, split them into two groups, and then followed them for two weeks. During the first week, one group ate a 12-ounce serving of vegetarian soup from a common brand of canned soup every day for five days; the other group, meanwhile, ate 12 ounces of vegetarian soup made from fresh ingredients each day. Then, after a two-day soup-free “wash out” period, the groups switched roles and were followed for five more days. At the end of each five-day period, the subjects provided urine samples. Dr. Michels noted that all the participants were fed amounts of soup that were smaller than what people probably would consume on their own. “One serving of soup is a not a lot,” she said. “They were actually telling us that that wasn’t even enough for their lunch.” In general, most studies have found that urinary BPA levels in typical adults average somewhere around 2 micrograms per liter. That was roughly the levels the Harvard researchers found in the subjects after a week of eating the soup made from fresh ingredients.

After eating the canned soup, though, their levels rose above 20 micrograms per liter, a 1,221 percent increase. Dr. Michels said that her co-authors, including one researcher at the Centers for Disease Control and Prevention who regularly analyzes BPA levels in studies, were stunned when the results came back. “She called me and said something’s funny with these levels,” she said. “She didn’t know what she was looking at.” Dr. Michels said that the increases in BPA were most likely temporary and would go down after hours or days. “We don’t know what health effects these transient increases in BPA may have.” But she also pointed out that the findings were probably applicable to other canned goods, including soda and juices. “The sodas are concerning, because some people have a habit of consuming a lot of them throughout the day,” she said. “My guess is that with other canned foods, you would see similar increases in bisphenol-A. But we only tested soups, so we wouldn’t be able to predict the absolute size of the increase.”

Many companies began phasing out BPA in baby bottles and other plastic food containers in recent years to ease public anxieties, but it is still widely used in the linings of metal cans because it helps prevent corrosion and is resistant to high heat during the sterilization process. “I don’t know how important bisphenol-A is to the lining of these metal cans,” Dr. Michels said. “Can you make the lining to protect the contents of the can without bisphenol-A? If this is the case, then we would suggest taking it out, because then you would eliminate the problem.”