“Microwaving food in plastic releases harmful chemicals.”
Some plastics do release small amounts of chemicals and tiny particles when heated, but harm to people from normal use of microwave-safe containers has not been shown.
You do not need to fear reheating leftovers in a plastic container. The simple habit is to use containers meant for the microwave, and to switch to glass or ceramic if you would rather keep plastic out of the picture.
Use containers labeled microwave-safe, or glass or ceramic if you prefer, and toss plastic containers that are cracked or worn.
Lab tests show some plastics give off small amounts of chemicals and tiny particles when heated, but no study has shown that this harms people at normal use, so "harmful" goes beyond the evidence. Confidence is limited because the evidence is lab testing of containers and cells, not studies of people's health.
Some plastics do release small amounts of chemicals and tiny particles when heated, but harm to people from normal use of microwave-safe containers has not been shown. Lab tests find the release; finding a release is not the same as finding harm.
In one lab test, three minutes in a microwave released up to about 27 million microplastic and 14 billion nanoplastic pieces from each square inch of some baby-food containers, using water or a mild acid in place of food. Extracted particles killed about three out of four human kidney cells in a dish, but only at a very high concentration, which is not the same as eating a meal. A test of 18 brands of polycarbonate baby bottles heated with water in a microwave found BPA levels well under the European limit at the time, and microwaving did not raise BPA release over repeated heatings. Another lab test found small amounts of one phthalate moving from plastic containers into water, with more from older containers heated for longer. In the U.S., materials that touch food must be cleared for the way they are meant to be used, including heating conditions.
- Hussain KA, Romanova S, Okur I, Zhang D, Kuebler J, Huang X, Wang B, Fernandez-Ballester L, Lu Y, Schubert M, Li Y. Assessing the Release of Microplastics and Nanoplastics from Plastic Containers and Reusable Food Pouches: Implications for Human Health. Environmental Science & Technology. 2023;57(26):9782-9792. DOI: 10.1021/acs.est.3c01942. PMID: 37343248
- Ehlert KA, Beumer CW, Groot MC. Migration of bisphenol A into water from polycarbonate baby bottles during microwave heating. Food Additives & Contaminants: Part A. 2008;25(7):904-910. DOI: 10.1080/02652030701867867. PMID: 18569009
- Moreira MA, André LC, Cardeal ZL. Analysis of phthalate migration to food simulants in plastic containers during microwave operations. International Journal of Environmental Research and Public Health. 2013;11(1):507-526. DOI: 10.3390/ijerph110100507. PMID: 24380980
- Keller and Heckman LLP. What are FDA's Regulations on Food Packaging and Microwave Use? PackagingLaw.com, Ask an Attorney. January 13, 2009