Can You Microwave Styrofoam?
Only if the container is made for it. The FDA says to use microwave-safe cookware specially manufactured for use in the microwave oven, and that some plastic containers should not be used in a microwave because they can be melted by the heat of the food inside. The USDA’s Food Safety and Inspection Service says foam insulated trays and plastic wraps on fresh meats in grocery stores are not intended to be heated and may melt when in contact with hot foods, allowing chemical migration into the food.
The chemical of concern is styrene. The National Toxicology Program says the rate at which styrene monomer migrates from polystyrene containers is determined mainly by how fat-soluble the food is, the container’s surface area per volume of food, how long they are in contact, and the food’s temperature.
The National Toxicology Program lists styrene as reasonably anticipated to be a human carcinogen, based on limited evidence in humans, sufficient evidence in experimental animals and supporting data on how it may cause cancer, and IARC classifies styrene as probably carcinogenic to humans, Group 2A.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Government sourceThe FDA says containers can become hot from the heat of food cooking inside, and that some plastic containers should not be used in a microwave oven because they can be melted by that heat. US FDA ↗
- Government sourceThe FDA advises following the oven manufacturer’s instructions and using microwave safe cookware specially manufactured for use in the microwave oven. US FDA ↗
- Government sourceThe USDA Food Safety and Inspection Service says foam insulated trays and plastic wraps on fresh meats are not intended to be heated and may melt when in contact with hot foods, allowing chemical migration into the food. USDA Food Safety and Inspection Service, via web.archive.org ↗
- Government sourceThe National Toxicology Program lists styrene as reasonably anticipated to be a human carcinogen, based on limited evidence in humans, sufficient evidence in experimental animals and supporting mechanistic data. National Toxicology Program, via NCBI Bookshelf ↗
- Government sourceThe National Toxicology Program says styrene migration from polystyrene containers depends mainly on the food’s lipophilicity, container surface area per volume of food, duration of contact and food temperature. National Toxicology Program, via NCBI Bookshelf ↗
- Government sourceIARC classifies styrene as probably carcinogenic to humans (Group 2A). IARC Monographs Volume 121, via NCBI Bookshelf ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.