Dear Peggy: I live alone, and cooking in the microwave is easy and convenient. I've heard all different messages about how and what kind of containers are safe for microwave cooking. I am especially wondering if there is a time or power level which would be safe to warm or cook in or under plastic. Is it true that plastic wrap is unsafe and can cause harmful effects if ingested? —E.B., Salisbury, Maryland
The answer actually depends more on the plastic than on the microwave setting. Look for plastic wrap that specifically says it's microwave-safe, and don't let the plastic wrap actually touch the food during microwaving. The USDA recommends using microwave-safe plastic wrap, waxed paper, cooking bags, parchment paper and white paper towels. Plastic storage containers of any sort are not advised.
Margarine tubs, take-out containers, whipped-topping bowls and other one-time-use containers are not a good choice for the microwave. These containers can warp or melt, possibly causing harmful chemicals to migrate into the food. Other poor choices include plastic storage bags, brown paper or plastic grocery bags, newspapers and aluminum foil.
Always use a microwave-safe dish and cover with the dish's lid or with one of the items suggested above. But don't allow the cover to actually touch the food.