Can you put Styrofoam in a microwave?

by | Feb 18, 2021 | Appliance Advice

We wouldn’t want you to throw away leftovers from last night’s tasty supper, wouldn’t we? After all, heating leftovers is part of the reason why microwaves were invented in the first place. But with it also comes the question, “Can you put you put and heat Styrofoam in a microwave?” Am glad you asked because we really have to careful with what we put in our mouth.


First and foremost, we are very proud of you for making the conscious decision of caring for your health. But before we deliver our verdict, we’d like you to first know some life-saving facts on Styrofoam. We shall begin by first clearing out some misconceptions that many have with regards to this topic.


Cancer is a big deal and that is why experts have for a long time warned against microwaving food in plastics since it might release some carcinogenic chemicals such as dioxins into your food. However, the misconception here is that plastics generally contain dioxins. This is not the case since these chemical substances are only produced when plastics are melted.


Point 1: Plastic only produce carcinogenic chemicals such as dioxins when heated to its melting point.


What Is Styrofoam?


I promise that we are going to keep this simple yet detailed without sounding too “sciency.”


Styrofoam is a product name that simply refers to any substance used to temporarily hold food and drinks. Just as the name suggests, it is foamy and very light compared to the conventional food containers we know.


Styrofoam is actually made up of a polymer substance known as Polystyrene. It is also important for you to know that polystyrene is plastic. Polystyrene is then composed of other chemical substances such as benzene and styrene. Now, these two chemical substances are the guys you wouldn’t want to put in your body.  Over the years, scientists have conducted several extensive tests on these two substances and labelled them as Carcinogenic, meaning that they can cause cancer. In addition to that, it’s not only cancer you need to worry about but also other problems with the reproductive system that they are likely to cause.


Point 2: Styrofoam is made up of a substance known as polystyrene, which is a plastic.


If you join the dots between Point 1 and point 2, then what we are simply saying is that under no circumstance should you heat food using Styrofoam if there’s a chance it will melt. Once it melts, this is when harmful carcinogenic chemicals migrate into your food.


Types of Styrofoam.


In case you didn’t know, there are two types of Styrofoam that you have probably crossed paths with:


  • Traditional Styrofoam.
  • Modern Styrofoam.


Traditional Styrofoam.


This type of Styrofoam is certified for normal temporary storage purposes such as holding your already headed food or drinks. Under no circumstance should you use it when heating food, especially when a microwave is to be involved? This is because once it is exposed to high temperatures, it has the tendency of melting and therefore releasing the toxic styrene and benzene chemicals. In short, it is not microwave friendly.


Don’t get worked out because of the fear of using these types of Styrofoam unknowingly because most of the restaurants today label whether or not their packaging is microwave friendly.


Modern Styrofoam.


This one is also known as the Microwave safe Styrofoam. Its physical characteristics are very similar to traditional Styrofoam being both foamy and light in most cases. However, the difference comes about when you study its chemical composition. It’s actually made up safer, different, and less toxic substances when compared to the traditional Styrofoam.


After running this substance through a series of tests, the FDA has certified the modern Styrofoam as being safe for normal use and heating as well. In fact, it is a requirement that restaurants and other food vendors to state or label whether or not their Styrofoam packages are safe to be heated together with food in a microwave.


Despite all this, it is still upon you the consumer to check your products for any warning and label.


Point 3: There are two types of Styrofoam, traditional and modern. KEEP OFF traditional Styrofoam or any unlabeled Styrofoam packaging you might come across. Heat your food only using the modern and usually labelled microwave-safe Styrofoam.


Common scenarios you might be faced with.


Take-out food.


If your food comes in a Styrofoam box then ought to be careful since it is riskier. To be on the safe side, simply transfer your food onto a plate then happily warm it your microwave.


If it comes in a cardboard box, then you are free to go ahead and heat your food using your microwave. Just remember to never microwave your food with any metallic components such as spoons.


Coffee cups.


Don’t dare try to warm your coffee in one of those. Why? Because this type of Styrofoam is usually used for temporary purposes when the coffee is already heated and warm. It is very unstable and most likely to melt should it be subjected to high temperatures.


Instead of risking your health why shouldn’t you just pour your coffee into another normal mug then now warm it using your microwave.


Noodle cups.


It depends. Is there a sticker or notification on the cup stating that it is microwave safe? Most of them are but few are not to be used for heating purposes. If not then don’t even think about it. Just switch over to another bowl and you should be good to go.


Throwaway plates.


These cheap bulky plates have recently been replaced by the much safer and lighter paper plates. You are free to put paper plates in your microwave unless your food is greasy or oily. If that’s the case then again transfer your food onto another glass plate.


Point 4: You can only put microwave-safe Styrofoam in your microwave. How will you know whether or not it’s safe? Check the label.




It’s recommended that you avoid warming food with Styrofoam, whether or not they are microwave safe or not unless you have no other alternative. All in all, before you put Styrofoam in your microwave, confirm whether or not it is microwave safe by checking the label.

For expert microwave or appliance repairs in Victoria BC. Call on the professionals at Victoria Appliance Repair today.

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Mike Smith Appliance Expert Writer

Mike Smith

I’m Mike Smith. With a strong technical background and an Appliance Repair Technician Certification (ASTC), I’m deeply committed to writing helpful content that addresses common appliance issues. My technical expertise allows me to provide reliable and straightforward advice to homeowners. I hope my articles can help you solve your appliance problems and extend their lifespan.


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