Is it safe to microwave frozen meals in their plastic trays?
Avoid it when you can. Microwave-safe plastic still heats food in direct contact with plastic.
What's actually in it
Frozen meal trays are often thin plastic. The label may say microwave-safe. That usually means the tray should not melt or collapse when used as directed. It does not mean zero plastic particle release or zero migration.
Frozen meals also heat unevenly. Sauce, cheese, oil, and tray edges can get very hot while other parts are still cold. That is a tough job for a disposable plastic tray.
What the research says
A 2023 study in Environ Sci Technol found microwave heating caused the highest microplastic and nanoplastic release from tested plastic containers and reusable food pouches. Some tested containers released large numbers of particles within 3 minutes.
A 2023 study in Food Chem found polypropylene glycol substances transferred into food during microwave cooking in plastic containers. The researchers also identified a new substance formed from a plastic migrant and a natural food component.
When you can, move the frozen meal to glass or porcelain before full heating. Cover it with a paper towel, porcelain plate, or microwave-safe glass lid. If the meal will not release from the tray while frozen, warm it briefly, transfer it, then finish heating.