Can You Microwave Styrofoam? TESTED!

Styrofoam is commonly used in coffee cups and take away containers and you might find yourself wanting to heat something up and wondering “can you microwave styrofoam?”

Will it blow up the microwave or catch on fire? Is it safe to microwave and what about the health effects? Will it leach chemicals into my food or drink that are harmful to me?

While I don't personally use a lot of polystyrene I do use them in noodle cups so I wanted to do the research (and experiments) to see if you can microwave styrofoam or not. Here's what I found:

You can microwave styrofoam without it catching on fire, melting or causing damage to your microwave. However, it may have negative health effects. The probable carcinogen styrene is proven to leach from styrofoam especially at high temperatures. Microwaving food in styrofoam is therefore likely to increase your chance of getting cancer.

You should avoid heating food in styrofoam and instead put it into a glass or ceramic container to warm up.

I've done experiments myself and tried to cook or excessively heat up polystyrene in the microwave. I've also dived deep into the research about the health dangers with polystyrene and whether or not it could potentially add to your chance of getting cancer.

In this article I'll share with you my finding and the personal decision I came to about whether or not I will be microwaving polystyrene moving forward.

What Happens When You Microwave Styrofoam?

I did a bunch of tests with styrofoam in the microwave. Heating up noodle cups, comparing styrofoam to glass and how easily I could heat up a cup of water as well as putting a styrofoam cup in the microwave with nothing in it to see what would happen.

Overall the results were pretty unwhelming.

When you microwave styrofoam nothing of note happens. The food or drink inside your styrofoam cup will warm up just like it would in glass or ceramic and a styrofoam cup by itself will get hot but won't melt, create sparks or set on fire.

Below you can see my experiments with styrofoam in the microwave.

As you can see in the video above nothing really happens to the styrofoam when it's put in the microwave.

Can Styrofoam Catch Fire in the Microwave?

Is it possible for styrofoam to get so hot and catch fire in the microwave and break your microwave?

From my personal experience and the research I have done polystyrene won't catch fire in the microwave. It starts to deform at around 110-120ºC (230-248ºF) and starts to melt at 160ºC (320ºF) but won't catch on fire until it reaches extremely hot temperatures that are unlikely in a microwave.

According to springerlink it starts to vaporize at 160ºC but doesn't become completely volatile until around 460-500ºC

There is a 17 second video on YouTube where it appears that people created a fire in a microwave. You can check it out below:

You'll notice in the video that nothing really happens to the styrofoam container itself but rather the side of the microwave lights up.

This is potentially a creation of plasma, which is super heated gas that creates an electric current and grows in the microwave.

If left on this can cause damage to your microwave but you'll notice as soon as they turn off the microwave the plasma/fire disappears.

I tried to replicate this but I couldn't and I haven't seen any other videos or couldn't find any other mention on this phenomenon anywhere online.

Is It Safe To Microwave Styrofoam? Are There Health Risks?

Ok, now we get down to the real reason you probably shouldn't microwave styrofoam.

It is NOT safe to microwave styrofoam! Styrofoam is proven to leach the probable carcinogen styrene into hot drinks. This means microwaving food or drinks inside styrofoam leaches likely increases your chances of cancer.

What we call styrofoam is either extruded polystyrene or expanded polystyrene (more details here). Polystyrene is made from styrene which is polymerized (learn more).

Why polystyrene is different from styrene it has been shown that residual styrene remains in styrofoam cups, bowls, plates and other containers. While the quantities of styrene are not incredibly high, they are still there.

This medical article also shows that polystyrene cups and water bottles are proven to leach the dangerous styrene chemical into the water, with temperature playing a major role in the leaching of styrene from styrofoam cups.

The higher the temperature the more leaching occurred!

Temperature (ºC)Styrene (µg/L)

This report concluded that:

Considering the toxic characteristic of styrene and leaching in water and other products, polystyrene (PS) material should be avoided for food packaging. Especially PS rigid and foam cups should not be used for hot drinks. Paper cups are safe for hot drinks and have no threat as from PS cups. It is also recommended that public awareness program shall be launched to avoid Styrofoam cups for hot drinks.

This quantitative analysis also proves the presence of the harmful chemical styrene in polystyrene products as well as the leaching of styrene into drinks.

Styrene increases your chance of getting cancer and also has a variety of other negative health outcomes.

This article and review by ScienceDaily states some interesting facts about styrene:

  • “the most recent styrene study shows the risk of acute myeloid leukaemia, a rare form of leukemia, is doubled”
  • “Another important research result is a fivefold risk for a particular type of nasal cancer following styrene exposure.”

Interestingly in 2011 the NIH said “The greatest exposure to styrene in the general population is through cigarette smoking.” – view source

This article from the National Library of Medicine also states:

‘Studies in the reinforced-plastics industry provided evidence that suggests a possible association between styrene exposure and cancer of the esophagus or pancreas.’

Hence, based on both animal and human cancer studies and genotoxic findings including clastogenicity and DNA damage in workers as well as on other supportive and biologically plausible mechanistic results, styrene and styrene-7,8-oxide should be considered as presenting carcinogenic risks to humans, particularly for lymphatic/hematopoietic cancers.

Will I Personally Be Microwaving Styrofoam Ever Again?

Luckily in Australia coffee comes in paper cups

After doing the experiments myself and diving into the research where do I do stand on this topic?

Would I personally microwave styrofoam?

Given my new found knowledge I will actually likely never consume food or drinks in styrofoam containers again, especially hot food or drinks.

I won't microwave them and I won't get takeout in them if I can avoid them.

Noodle cups and other food that are sold in polystyrene I will try to avoid buying and if I do buy it I will transfer the food to a glass or ceramic cup or bowl before cooking them.

It's honestly just not worth the risk, plus it's horrible for the environment.