Freezing or microwaving plastic: Does it release dioxins?

Date updated: January 22, 2007
Content provided by MayoClinic.com

Does freezing or microwaving plastic food containers cause them to release dangerous toxins?
Gene, New York
No. Stories have circulated for years that freezing or microwaving plastic food containers or wraps causes them to release cancer-causing substances called dioxins. But this isn't true. In fact, there's no evidence that plastic food containers or wraps even contain dioxins.
According to the Food and Drug Administration, freezing and microwaving plastic food containers and wraps are safe. Although small amounts of chemicals used to make certain plastics may leach into food, any chemicals that do leach into food are within safe limits.
To ensure the safe use of plastic in the microwave, use containers or wraps specifically labeled as "microwave-safe." Margarine tubs, carryout containers from restaurants, and plastic grocery bags shouldn't be used in the microwave.
Check the label on packaged foods. If you don't find instructions for microwave use, use a different plate or container that you know is microwave-safe to heat the food.
In addition, microwave-safe plastic wrap shouldn't directly touch the food. The labels on some plastic wraps recommend that you leave a 1-inch space, or greater, between the plastic and the food during microwave heating.