What Is Microwave Safe Plastic?

FDA Studies

• In response to these worries, the FDA (Food and Drug Administration) tests different types of plastics, sets standards for plastic container safety and reviews all plastic containers for compliance before approving their use in microwave ovens. The FDA tests consider the food to plastic surface ratio, the length of cooking time, how high the temperature of the food reaches, how often the container is used for eating as well as cooking, and which chemicals are prone to leaching into foods and in what amounts. Plastic containers must release chemicals in much smaller amounts than those shown to cause harm to laboratory animals. If containers pass the test, the FDA authorizes the manufacturer to label them as microwave safe.

Safe Choices

• Sets of lidded, plastic household food storage containers are typically labeled as safe or unsafe for microwave use. If there are no guidelines, the safest option is to transfer the food to a microwave-safe ceramic or glass container for heating or cooking. Using plastic wrap with a vent cut in the top to cover food is acceptable but it's advisable to keep the wrap from touching the food as it may infuse it with trace chemicals or adhere to the food and render it inedible.

Unsafe Containers

• Plastics shown to leach unacceptable amounts of chemicals into foods include the bulk of takeout containers and cartons, bottles used for commercially sold water, and bowls, tubs or jars in which butter, margarine, cream cheese, whipped toppings, mustard and yogurt are sold. If microwave dishes and trays in frozen food products are labeled safe for one time use, discard them accordingly. Plastic bags in which food is sold or packaged, as well as food storage and freezing bags used by homemakers, are not safe for microwave use.

Microwave Container Hints and Tips

• To minimize the intrusion of plastic chemical transference and off-putting tastes, loosen the lids of plastic microwave containers to let the food breathe during cooking. Check Styrofoam packaging for microwave safety labels, as some types will melt or emit harmful chemicals in microwave ovens. When possible, reheat foods in the microwave covered with unbleached and undecorated paper towels, wax or parchment paper, or uncoated paper plates.