Can You Safely Microwave Styrofoam?

Picture this: You've got last night's takeout, and you're really hungry. Instead of waiting for the oven or a saucepan to heat up, you toss the Styrofoam container straight into the microwave, but there's a nagging question in the back of your mind, should you actually be doing that? The short answer is probably not.

Not all Styrofoam containers are created equal. Some are approved for use in the microwave by the Food and Drug Administration, while others aren't. If your container has a little microwave-safe symbol (those wavy lines), you can microwave it. But if it doesn't? You're playing a risky game by microwaving the container as heating Styrofoam that isn't microwave-safe can cause it to melt, release harmful chemicals, or even catch fire. Aside from the dangers of microwaving Styrofoam, there are also concerns as to how effective it is. So, while you can microwave some Styrofoam safely, you might not always want to.

As we have mentioned, not all Styrofoam is microwave-safe and, beyond the potential for it to start a fire, there are other concerns to consider. In its 15th Report on Carcinogens, the National Toxicology Program noted that styrene, a key component of Styrofoam, is most likely a human carcinogen. When exposed to heat, some of this chemical can end up in your food, particularly if you're reheating fatty foods like meats or cheeses or if the container itself begins to melt. While occasional exposure may not be a major health risk, consuming food contaminated with styrene is definitely not something you want to make a habit of.

As a result of these concerns, several states have banned Styrofoam containers. Maine was the first state to ban polystyrene food packaging and other states, including California, Oregon, and Delaware, have since followed suit. Many of the states that banned Styrofoam have noted that the material's unsustainability contributed to the decision; aside from being potentially harmful to humans and animals, Styrofoam also takes up to 500 years to break down.

Even if your Styrofoam container is labeled microwave-safe, you probably shouldn't use it to reheat food. This is because Styrofoam doesn't allow for food to be heated evenly. Due to its cellular structure, Styrofoam is good at insulating foods, but it is not good at conducting heat. This ultimately means that your food might warm up on the outside while staying cold in the middle.

The best way to reheat food safely is to transfer it to a microwave-safe glass or ceramic container. Not only are these materials safer than Styrofoam, but they will also result in your food reheating more evenly. 

Thankfully, some companies are starting to move away from Styrofoam containers, making it easier for customers to effectively and safely reheat their food. For example, Cup Noodles made the switch from Styrofoam to paper containers that are microwave-safe. So, while the verdict is out on whether alternatives like microwave-safe plastic are actually safe, there are plenty of safe, effective packaging options out there.