Some plastic products are considered safe for use in a microwave oven, while other types of plastic will melt or leach chemicals into your food during microwaving. Plastics that are approved by the FDA for microwave use will either be labeled with words or a symbol depicting a microwave oven or waves, or its packaging may include directions for proper microwave use.
About Microwave-Safe Plastics
Before the FDA will approve a plastic container or other product as safe for microwaving, the product must undergo thorough testing. A material is approved only when it has been shown to meet the FDA’s strict standards. These approved plastics will not melt or leach unhealthy amounts of chemicals into your food when microwaved under typical conditions and according to instructions.
Examples of Microwavable Plastics
Microwave-safe plastics include many containers, trays, packages, wraps, and other products intended to be used with food. These days, reusable food storage containers are often rated as safe for microwaves. Most types of plastic wrap are now also safe, although it is often recommended that you do not allow the film to touch your food during heating, as this could cause a temperature increase that may lead to melting. Some plastic packaging, such as the trays that come with microwavable dinners, are safe for one-time use only.
Plastics Not Intended for Microwave Use
A plastic product without microwave-safe labeling may not have met FDA standards, or it may not have been tested for this purpose at all. Some of these unlabeled products may actually be safe for microwaving, but there is no way for you to know for sure. Some types of containers that are usually not designed for microwave use include plastic tubs that originally contained foods like margarine, whipped topping, or cottage cheese. Also in this category are plastic bottles or jars that held water, juice, salad dressing, peanut butter, or similar products, as well as most takeout containers and to-go boxes from restaurants.
The Harvard Medical School Family Health Guide
Microwaving Food in Plastic, Dangerous or Not?
Using Plastics in the Microwave
Plastics and Food