Kiren Chauhan and Brandel France de Bravo, MPH, National Center for Health Research
Emails continue to circulate about the dangers of using plastic wrap in the microwave. One version of the email claims that dioxin, a known carcinogen, is released from plastic wrap into food when heated. Most of those emails have been proven to be hoaxes that do not come from the universities or authorities cited, and it seems unlikely that plastic wrap emits dioxin. On the other hand, of the 80,000 chemicals produced and used in the U.S. today, the Environmental Protection Agency has required testing on only 200. So, let’s look into this issue more carefully.
What harmful chemicals, if any, does plastic have? Two major chemicals to watch out for are phthalates (used to soften plastics) and bisphenol A (BPA), which is used to make very hard, shatterproof plastic (it usually has #7 on the bottom) and is also found in the lining of canned foods and beverages. When phthalates and BPA get into our bodies, they affect estrogen or testosterone. Researchers have linked BPA, phthalates, and other chemicals known as endocrine disruptors (these act like hormones in our body and affect our natural hormone production) to cancer, problems in the reproductive organs, and several other health problems. That’s why six phthalates are banned by law from children’s products, and why the FDA is studying BPA to determine if it should be banned from baby bottles and the lining of food and beverage cans. Plastic wrap does not typically contain BPA or phthalates, although in tests done by Good Housekeeping magazine in 2008, the labs found very low levels of phthalates and BPA in Glad brand “Press n’Seal” wrap.
Plastic wrap in the United States is made of polyvinyl chloride or PVC and contains a “plasticizer” called di(2-ethylhexyl)adipateor DEHA. DEHA is not a phthalate but is chemically very similar to the phthalate DEHP, which is di(2-ethylhexyl)phthalate).
Studies in the 1990s showed that DEHA can cause liver tumors in mice, and other studies showed that DEHA migrates from plastic wrap into food—particularly high fat foods such as cheese. A 1998 study by Consumers Union tested plastic-wrapped foods and found DEHA levels higher than what is recommended and even permitted by European advisory committees and regulatory agencies. The FDA, however, has not established a limit for how much DEHA is safe in our food because there is insufficient data on its health effects on humans and no government body has classified it as a cancer-causing chemical.
I don’t eat a lot of canned food and I don’t drink soda. Are there other ways that chemicals found in plastic could be getting into my food? Many foods are sold in plastic containers and most of us keep leftovers in food storage containers made out of plastic, like Tupperware, Rubbermaid and other brands. While none of these containers seem to be made with phthalates, some may have BPA. Rubbermaid’s website states that it currently makes no products with BPA or phthalates (if you want to see if any of your older Rubbermaid products contain BPA, check here). Tupperware says that ten percent of its products contain BPA but it fails to list which ones.
Just because a plastic food container is phthalate and BPA-free doesn’t mean it’s entirely safe. Even very hard plastics like the ones with BPA in them break down over time, which means they can potentially release trace amounts of whatever chemicals they are made of into the food. This is more likely to happen when the plastic has been heated or when it’s old and has been subjected to repeated use or washings. Perhaps these chemicals are harmless, but there isn’t any research on the cumulative effect of constantly eating food stored or heated in these plastic containers. It would not be surprising to find out that they may not be as safe as we thought.
So what about all that food we buy that says to microwave it in the plastic container it’s sold in? That type of plastic is “microwave safe” (there is a microwave safe symbol which shows many wavy lines stacked on top of each other), but this means it won’t melt in the microwave—it doesn’t mean that it won’t release small amounts of chemicals into your food. Anything not marked “microwave safe,” will soften and lose its shape in the microwave. “Take out” food containers or other disposable plastic food containers (like the ones that refrigerated foods such as soft cream cheese or butter are sold in) are especially unsafe to use in the microwave. In their study, Good Housekeeping researchers microwaved food in a variety of plastic containers labeled microwave safe and found no detectable levels of BPA (or phthalates) in most. But if your favorite containers are the kind that has these chemicals, and add to that all the other ways you can be exposed to BPA or phthalates, you could end up with unhealthy levels of these chemicals in your body. Two Canadian environmentalists experimented on themselves for four days by exposing themselves to various chemicals found in food and beverage containers and other household objects and wrote a book called Slow Death by Rubber Duckie!
We need more research to know what plastics are safe—under what conditions and for what use. Until we have that information, you can “play it safe” and reduce the amount of chemicals getting into your food from plastic by following these tips:
- Avoid allowing plastic wrap to come into contact with food, especially when heating or if the food has a high fat content (like meat or cheese). Saran Wrap’s official website recommends a one-inch gap between the plastic and food. If you want to prevent food from splattering in the microwave, cover it with a microwave-safe dish or a paper towel.
- Use glass or ceramic containers to microwave food and beverages, and avoid microwaving in plastic or disposable containers.
- Since BPA is in the lining of nearly all canned foods and beverages, use frozen or fresh foods instead of canned, whenever possible. Get rid of older canned goods, especially those that contain tomatoes, because tomatoes’ acidity can increases the leaching of BPA into food. When buying tomato sauce products, choose brands sold in glass jars. You might want to consider buying canned foods from Eden Organic, because it does not use BPA in its cans (except for its tomato products).
- Look for drinks sold in cartons or glass. Some of the glass bottles may have lids lined with BPA, but even so, the top is not usually in contact with the beverage. If you carry a reusable water bottle, switch to stainless steel or look for a sports bottle that is “BPA-free.” [Do NOT re-use the kind of plastic bottles that bottled water is sold in, because they are not safe for repeated use.] Plastics that contain BPA are usually very hard and may have the number seven on the bottom.
Not all plastics with the number seven contain BPA, but all plastics break down when exposed to heat—whether in the microwave or dishwasher—and strong soaps. Cracks and cloudiness are signs that a clear, reusable plastic container has started to break down and may be releasing BPA into your beverage or food.
All articles on our website have been approved by Dr. Diana Zuckerman and other senior staff.
“Reducing Environmental Cancer Risk, What We Can Do Now.” 2008-2009 Annual Report, President’s Cancer Panel. http://deainfo.nci.nih.gov/advisory/pcp/annualReports/pcp08-09rpt/PCP_Report_08-09_508.pdf
“Saran Wrap: Frequently Asked Questions.” http://www.saranbrands.com/faq.asp
“Eden Organic: Frequently Asked Questions.” http://www.edenfoods.com/faqs/
USDA Food and Inspection Service, Fact Sheet: “Cooking Safely in the Microwave :/www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/appliances-and-thermometers/microwave-ovens-and-food-safety/ct_index
Consumers Union. Report to the FDA Regarding Plastic Packaging. 1998. http://www.consumersunion.org/pub/1998/06/002284print.html