Which Plastics Are Safe To Put in the Microwave?

With all of the warnings about the dangers of plastics in the microwave, along with the many plastics available today, it's no wonder consumers would be confused about what to and what not to zap in the kitchen.

The easiest way to figure out if a plastic container is safe for the microwave is to look for the Microwave Safe symbol. This stamp of approval, which includes three wavy lines to symbolize radiation, basically says that the container can withstand the heat of the microwave without melting or releasing harmful amounts of chemicals.

Microwave-safe containers go through stringent FDA testing to ensure that, at temperatures reached in the microwave oven, the amount of chemicals that leach out of the plastic is no more than 100 to 1,000 times less than the amount shown to harm lab animals.

Unlabeled plastic containers aren't necessarily unsafe for the microwave. But the lack of label just means that these plastics haven't gone through the battery of tests required to ensure microwave safety. Because there's no way to tell if these containers can hold up to microwave heat, it's best not to use them in the microwave.

And while some containers are labeled with plastic type, such as PET (polyethylene terephthalate), this doesn't give you enough information to determine if it's microwave-safe. For example, some PET containers are safe for the microwave while others are not.

Below is a list of tips from The Harvard Medical School to guide you in using plastics in the microwave:

  • Most take-out containers (like the ones used to carry home your favorite Chinese meal), water bottles, and plastic tubs made to hold butter, cream cheese and yogurt are not microwave safe.
  • Microwaveable take-out containers designed for one-time use should not be re-microwaved.
  • Plastic storage bags (except those labeled as Microwave Safe) and grocery bags are not recommended for the microwave.
  • When using plastic wrap to cover a food dish, make sure it's not touching the food.

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Michelle Bryner
Michelle writes about technology and chemistry for Live Science. She has a Bachelor of Science in Chemistry from the Salisbury University, a Bachelor of Chemical Engineering from the University of Delaware and a degree in Science Journalism from New York University. She is an active Muay Thai kickboxer at Five Points Academy and loves exploring NYC with friends.