If you're unsure about the safety of a material, it's beneficial to conduct a test. Briefly microwave a container with water (for about 30 seconds). If the container becomes hot, it's a sign that ...

The main safety tip to remember is to check ... microwaving" or point-blank instructions like, "Do not microwave." Another positive sign is that the cup is made from type 5 polypropylene.

"However, this heating doesn't clean the microwave itself or address the bacteria on handles and buttons from unwashed hands," she said. "This creates a shared responsibility in food safety ...