Can You Put Styrofoam In The Microwave?

can you put styrofoam in the microwave

There comes a time when we question whether or not it is safe to use a microwave to heat certain things.

Common knowledge says that materials such as metals (including aluminum foil) and most plastics are not meant to be microwaved and are potentially hazardous to one's food and ultimately one's health. But can you microwave Styrofoam?

In the case of plastics, it’s said that some types can be manufactured in a way that allows for usage in a microwave oven. Styrofoam is a type of plastic which is argued to be among those that are not normally microwave-safe, but that can be manufactured for microwave use as well.

Is it okay to microwave Styrofoam? We don't recommend it.

Common Styrofoam Items Being Microwaved

Styrofoam Containers
  • Coffee Cups – Often Styrofoam coffee cups are used to serve coffee and hot chocolate. They have also been used a cheap alternative to small bowls for serving soups, stews and chili.
  • Styrofoam Plates – These are cheap alternatives great for parties since they are cheap and disposable, but are often used to reheat food on the following day or people who have simply arrive late to the event.
  • Cup Noodles – Classic cup noodles typically have two sets of directions. One for simply adding boiling water, while the other may suggest filling with water from the tap and placing the entire thing in the microwave.
  • Take-out Containers – These are often used when ordering out or taking left overs home from a big meal at a restaurant. Instead of removing the contents and reheating the leftovers on another dish, it’s much easier to toss the whole thing in the microwave for 5 minutes.

Chemicals In Styrofoam

One of the main chemical components of Styrofoam is polystyrene which contains toxic molecules of styrene and benzene. They are chemicals that have shown potential carcinogenic and neurotoxic properties along with other detrimental side effects.

So the heated chemicals debate comes down to whether or not polystyrene is leeching chemicals in to our food when heated by a microwave oven.

The National Institute of Standards and Technology (NIST) have published many reviews that indicate polystyrene started to show signs of decomposition around 200 degrees celcius and showed small trace amounts of polystyrene being released.

Where it gets scary is around 224 degrees celcius where polystyrene actually starts to break down. For pure styrene the temperature is about 175 degrees.

You definitely don’t want to be cooking anything in Styrofoam at those temperatures! Cooking a pot roast in the microwave on Styrofoam is definitely out of the question.​ Microwaving plastic at those temperatures will most definitely melt the plastic.

Here is a video cooking Easter Peeps on a Styrofoam plate:​

​An easy way to clean that mess is on our site about how to clean a microwave with lemon and water.

Let’s take a cup of water as an example. Water boils at 100 degrees which is well below the point in which polystyrene has been recorded to release some of its self. But let’s say we’re getting some polystyrene in to our cup of water because the cup has melted.

If the cup weighs 5 grams and you are ingesting 10% of that cup, you would be ingesting about 500mg of polystyrene. The EPA suggests that for styrene that would be about the upper limit of what’s considered safe in the short term.

As for polystyrene facts we were unable to find the data. But if the cup melted and you weren’t chewing on pieces of melted Styrofoam, there is a good chance that there is styrene somewhere in there on its own.

But these two chemicals are not the only ones to worry about. Depending on the manufacturer, they have added other chemicals to their Styrofoam in efforts to reduce costs or create a “better” product that may break down at lower temperatures.

Potential Side Effects

Some of the potential consequences that can result from ingesting the chemical components of heated polystyrene may include:

  • Eye and stomach irritation
  • Headaches
  • Fatigue
  • Hearing loss
  • Clinical depression
  • Dysfunction of the central nervous system

As the risks of microwaving Styrofoam are largely unproven at this point in time, it is hard to say whether or not microwaving typical Styrofoam releases enough of these chemicals to cause harm to human health.

Benefits Of Microwaving Styrofoam

In contrast, microwaving Styrofoam can also provide a few benefits.

  • Convenience
  • Cost effectiveness
  • Disposability

Whether or not these benefits outweigh the risks is up to each individual.

Can You Put Styrofoam In The Microwave Safely?

Microwaving plastic is not something we feel comfortable with so it would also apply to Styrofoam. When in doubt, don’t do it.

Since there is little data to suggest it’s completely safe to put Styrofoam in the microwave, we don't recommend using Styrofoam in the microwave at all. There are many other options available and your health should be paramount.


  • Glass or Pyrex plates and bowls
  • Ceramic plates
  • Skip the microwave and a pot or pan for heating food or drinks

For the sake of your food and your health, be cautious about what you inside your microwave oven.

Did you enjoy this guide? Let us know if you put Styrofoam in the microwave and your biggest safety concerns.

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