Is it Safe to Microwave Food in Plastics?

A "microwave-safe" or "microwavable" label on plastic containers only means that they shouldn't melt, crack or fall apart when used in the microwave. These labels do not guarantee that containers don't leach chemicals into foods when heated; the U.S. Food and Drug Administration does not regulate these labels and has not developed any standards for them. As a precaution, Green Guide science advisor Lisa Lefferts always avoids using plastic in her microwave. "You don't want hot, fatty food touching plastic in the microwave," she cautions. "Plastic plus hot plus fat is the worst combination. That's because most chemicals that leach from plastic are lipophilic (they love fat) and temperature speeds up the leaching process into the fat."

For safety's sake, it's best not to heat foods in plastics. Ceramic or oven-proof glass (such as Pyrex) dishes provide safe and effective substitutes. To prevent splattering and ensure thorough heating (which kills harmful microbes), cover dishes with oven-proof glass lids or plates. Never microwave in margarine tubs, yogurt cups or other storage containers such as Styrofoam.