Can You Microwave Styrofoam? Is It Safe?

This post may contain affiliate links. Read my disclosure policy.

Using a microwave is a great way to heat up food fast but sometimes it's hard to know what materials are microwave safe. In the post we will discuss stryrofoam and answer the question, can you microwave styrofoam.

It's so easy to fall into the trap of, say, reheating our lunch in styrofoam boxes at work. While it does seem like the easiest and the quickest way to reheat our food, it might not be the best option.

In this article, we have rounded up everything you need to know about microwaving styrofoam like, can you microwave styrofoam and is it safe?

Related:

What is styrofoam?

For starters, let’s look at what exactly styrofoam is and what it's made of.

Basically, styrofoam is an aromatic hydrocarbon polymer made of styrene monomer. The material has a thin, brittle foam-like appearance, usually available in white color. If you depend on take out food, you must be aware of styrofoam's white disposable food packaging boxes or maybe styrofoam cups.

These styrofoam boxes are a convenient food storage option due to their lightweight structure and wide availability. However, styrofoam is not the best option when it comes to recycling. It doesn’t decompose quickly. In fact, a styrofoam box needs 50 years to decompose on its own, so the material is an environmental hazard.

For this reason of not getting decomposed, countries like China banned using the material in the food storage industry. However, the ban's implementation became a serious problem, and the food storage companies demanded the reversal of the decision.

A common misconception about polystyrene material comes with its name ‘Styrofoam.’ Styrofoam is a trademark foam brand from The Dow Chemical Company made of polystyrene. The name styrofoam, in reality, is not suitable for white food storage boxes. They should be called polystyrene boxes, but they got the popular name of styrofoam instead.

Can you microwave styrofoam

As a food storage option, most people want to microwave their food in the same styrofoam boxes. It seems quick and convenient to stick those boxes in the microwave. However, the question here is ‘Can you microwave styrofoam?’.

Although it looks like the best option to microwave styrofoam boxes, styrofoam in a microwave is a big NO-NO since it is not safe to do so. The styrene polymer will get soft at a mere 212 degrees Fahrenheit, and it will be completely melted at 464 degrees Fahrenheit. Make sure to transfer food into a microwave-safe container to heat.

Although it is unlikely to get styrofoam melted in the microwave oven, it can definitely soften the container and leach toxic chemicals into the food. The reason the microwave oven does not reach to melt the styrofoam is its temperature capacity.

Microwave ovens can achieve a maximum temperature of 212 degrees Fahrenheit, which is the exact temperature at which the styrofoam boxes will start to soften. You may argue that a microwave doesn’t necessarily achieve the highest temperature limit during a heating cycle, so it may not deform styrofoam.

But do you ever get to know when your microwave achieves 100 degrees Centigrade temperature limit? So, it is better not to keep styrofoam in the microwave to avoid any mishap.

Is it OK to heat up food in styrofoam?

Styrofoam is a good insulator which means that it keeps the food warm for longer periods. This material characteristic may give the wrong idea of it being microwave safe. However, microwaving food in styrofoam poses two potential threats:

The box may get deformed by heating.
Heated polystyrene products may leach materials into the food that can cause cancers.

There are two possible ways of heating food in styrofoam boxes. You can microwave them or put them directly on the flame. Unfortunately, none of them is a safe option. By microwaving, you risk the styrofoam molecules leaching into the food, which can cause cancers.

Directly putting a styrofoam box on the flame will cause a fire—A dangerous fire with fumes of Styrofoam's petroleum molecules.

So, none of the methods is safe to heat food in Styrofoam boxes.

The risk of deformation or leaching dangerous chemicals into the food comes with food-grade Styrofoam containers.

However, there is a variety of Styrofoam that is microwave safe. Let's see what it is.

How to tell if styrofoam is microwave safe?

Typically, there are two types of styrofoam containers—one which doesn't have a microwave-safe label on the bottom. The second one does carry a microwave- safe label. The microwave-safe symbol ensures that the container has been tested to withstand the microwave heat.

If you ever want to heat food in a type #6 plastic container (Styrofoam), check its bottom to find the microwave-safe symbol (a few waves).

Generally, though, type #6 plastic is not reusable, so it is better to avoid heating food in it. Even if there's a microwave-safe symbol on the container, you may face softening of the material inside the microwave.

If you experience softening a Styrofoam container in the microwave, discard it with the food. The softening contaminates the food and makes it unsafe for human consumption.

What to use instead of styrofoam

Although Styrofoam boxes seem to be a convenient reheating option, the ease is not worth the health risk associated with the practice. It may seem like a hassle, but the effort is worth it.

Here are some of the reheating material options instead of Styrofoam that can go inside the microwave oven without another thought:

Pyrex container

Pyrex is a brand of glass containers that are microwave safe. If you have a Pyrex container, they are the best and the safest choice to stick into a microwave.

Pyrex dishes are either made of Borosilicate glass or soda-lime glass, which are safe to go inside the microwave oven without the hassle of breakage.

However, even when using a Pyrex dish in the microwave, keep in mind that the plastic lids may not be microwave safe, so it is better to remove them.

Microwave safe glass or ceramic containers

Glass containers other than Pyrex can also be microwave safe. If the glass container you are using in your microwave oven carries a microwave-safe level on its bottom, you can put it in the microwave.

However, sometimes the containers do not carry the symbol, so there's an easy way to figure out if the glass container is microwave-safe or not.

Put the container and a cup filled with water in the oven and heat it to the highest setting. If on heating, the container remains cool, it is microwave safe.

Similarly, ceramic cookware is generally microwave safe due to its high heat resistance. So, instead of going for a Styrofoam container, use either a microwave-safe glass or ceramic dish to avoid any health risks.

How to safely heat food in the microwave

Although microwave ovens are among the most prevalent kitchen appliances, they have some do's and don'ts attached. It is better to be safe than sorry when dealing with an electrical appliance that can have some associated risks. Here are a few tips on heating food safely in a microwave oven:

Always check your food container for a microwave-safe sign before putting it in the microwave.
If you don't find one, it is better to avoid putting the container in the microwave.
Once you have a microwave-safe container, put the food you want to microwave in an even layer inside the container.
Do not supply continuous heat to the food; instead, heat your food in cycles.
Use a damp paper towel to cover the container; it will make some steam inside the container, which will help heat the food evenly.
Avoid plastics or materials such as Styrofoam in the microwave oven because they do mostly not microwave safe.
Never put metal inside the microwave, or you will watch a spark show in your kitchen.

Conclusion

Styrofoam is a cheap and widely available food storage material that is lightweight and a good heat insulator.

No matter how easy it is to store food in a Styrofoam container, it is not a good idea to heat food in it because the material cannot withstand high heat.

Putting Styrofoam in the microwave can deform the material at first, and if you keep heating it for a longer period, it will eventually melt.

Even at the softening stage, Styrofoam leaches chemicals into the food that can cause cancers. So, instead of choosing convenience, choose health and don't put Styrofoam containers in the microwave.