Avery Nork, Kiren Chauhan, Brandel France de Bravo, MPH, National Center for Health Research
Is it safe to warm up food in plastic containers or using plastic wrap in the microwave or the oven? In 2016, President Obama signed a law that strengthened the Toxic Substances Control Act that requires testing of chemicals to make sure they are safe. Prior to that law, more than 60,000 chemicals on the market had gone untested. With that enormous backlog, it may be decades before the EPA has tested the thousands of chemicals that are widely used today. 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. BPA, phthalates, and other chemicals known as endocrine disruptors act like hormones in our body and affect our natural hormone production. These types of chemicals have been linked to cancer, problems in the reproductive organs, and several other health problems.1 In addition, a 2023 study found that children exposed to phthalates in the womb or during their first year of life were more likely to develop behavioral, attention, and learning disorders. 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 has been ‘phthalate free’ since 2006, but in the United States it is made of polyvinyl chloride or PVC and contains a “plasticizer” called di(2-ethylhexyl)adipate or DEHA. DEHA is not a phthalate but is chemically very similar to the phthalate called DEHP.
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.2 A 2014 study found DEHA in various cheeses as well as beef, chicken, and pork that was sold in clinging plastic wrap at grocery stores.3 A 2021 study found that DEHA triggered brain and heart injuries in rats, but research is needed to better understand the risks for humans.4
Similarly, high density polyethylene (HDPE) plastic containers, which are typically used to store household cleaners and pesticides but are sometimes used for food storage, tested positive for PFAS. The results of a 2023 experiment showed that PFAS were capable of transferring into food, and that if there are PFAS in your food storage, it will transfer into your food over time. The researchers tested olive oil, ketchup, and mayonnaise and found that all of them had detectable levels of PFAS after being in contact with an HDPE for a week. While HDPEs are currently not intended for food storage, there is nothing stopping plastic companies from using them that way. This could be potentially harmful to thousands of people by exposing them to high levels of PFAS.
“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, such as Tupperware, Rubbermaid, other brands, as well as carryout containers from restaurants. While none of these containers seem to be made with phthalates (since those are usually relatively soft), some may have BPA. As companies have become more aware of the dangers of the plastics they were using, they replaced some chemicals with others. When we checked Rubbermaid’s website in 2023, it 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 all of its products are BPA free as of 2010, but any older products still might contain levels of BPA. If you want to check if your Tupperware is BPA-free, check the bottom of the container. Any number 1 through 6 means it is BPA-free, but a 7 means there might be BPA in that product. In addition, the company that makes Saran Wrap changed the chemicals in its product, making it less clingy but less dangerous to our planet.5
Regardless of whether a plastic food container contains phthalates or BPA, it may not be entirely safe. Plastics 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. In fact, numerous studies show that most, if not all, humans have microplastics in our bodies, often from the food and drinks we consume every day.6 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 many of us assumed.
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 said to be “microwave safe,”, 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.7 But if your favorite containers have these chemicals, in addition to all the other ways you can be exposed to endocrine-disrupting chemicals and microplastics, 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). 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.8
Although 96% of canned foods from major supermarkets that were tested in 2019 were BPA free, you might want to throw away older canned goods in your home that still might have BPA in the lining.9
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 make sure your sports bottle 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 hard and make a clicking noise if you hit them with your fingernail or a fork or other metal utensil, and may have the number seven on the bottom.
Remember that all plastics break down when exposed to heat—whether in the microwave or dishwasher—and when exposed to strong soaps. Cracks and cloudiness are signs that a clear, reusable plastic container has started to break down and may be releasing BPA or other chemicals into your beverage or food.
All articles on our website have been approved by Dr. Diana Zuckerman and other senior staff.
- National Institutes of Health. (n.d.). https://deainfo.nci.nih.gov/advisory/pcp/annualReports/pcp08-09rpt/PCP_Report_08-09_508.pdf
- Report to the FDA regarding plastic packaging. CR Advocacy. (n.d.). https://advocacy.consumerreports.org/press_release/report-to-the-fda-regarding-plastic-packaging/
- Cao, X. L., Zhao, W., Churchill, R., & Hilts, C. (2014). Occurrence of Di-(2-ethylhexyl) adipate and phthalate plasticizers in samples of meat, fish, and cheese and their packaging films. Journal of food protection, 77(4), 610–620. https://doi.org/10.4315/0362-028X.JFP-13-380
- Behairy, A., Abd El-Rahman, G. I., Aly, S. S. H., Fahmy, E. M., & Abd-Elhakim, Y. M. (2021). Di(2-ethylhexyl) adipate plasticizer triggers hepatic, brain, and cardiac injury in rats: Mitigating effect of Peganum harmala oil. Ecotoxicology and environmental safety, 208, 111620. https://doi.org/10.1016/j.ecoenv.2020.111620
- Emma KumerUpdated: May 18, 2023. (2023, May 18). Is it just us, or is Saran wrap less sticky?. Taste of Home. https://www.tasteofhome.com/article/why-todays-saran-wrap-is-less-sticky/
- Pinto-Rodrigues, A. (2023a, April 10). Microplastics are in our bodies. here’s why we don’t know the Health Risks. Science News. https://www.sciencenews.org/article/microplastics-human-bodies-health-risks
- Is it safe to heat food in plastic?. Good Housekeeping. (2022, August 16). https://www.goodhousekeeping.com/institute/a17859/plastic-safety-heat-food/
- Food Safety and Inspection Service. Cooking with Microwave Ovens | Food Safety and Inspection Service. (n.d.). https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/cooking-microwave-ovens
- Canned Foods. Center for Environmental Health. (2020a, January 27). https://ceh.org/products/canned-foods/