Before placing a food container in a microwave, check for labels or imprints on the bottom, side or lid of the vessel indicating it is microwave safe. Although most hard plastic storage containers, glass dishes and ceramic dinnerware are safe to use in the microwave, a verification label ensures harmless microwave cooking.
A number of plastic film wraps, paper towels, plastic cooking bags, wax papers and parchment papers are approved for microwave use and labeled as such. When covering foods with plastic wrap, avoid letting the wrap touch the food to prevent adherence to the food's surface.
Discard frozen or prepackaged food containers designed for one time use after the enclosed food has been cooked. Reusing these containers may impart the food with harmful chemicals or they may melt in the microwave. Never place paper bags, regular food storage bags, plastic grocery bags or aluminum foil in a microwave.