Can You Microwave Polystyrene? Your Questions Answered

Did you just go to your favorite restaurant last night and bring home some awesome leftovers? If so, you may be wanting to heat it back up for a quick meal. The container your food is in is most likely made of polystyrene, read on to find out if it’s safe to pop it in the microwave.

It’s best not to heat polystyrene in the microwave for longer than 30 seconds. Polystyrene is safe to reheat food in, but not safe to cook food in. If heated up to more than about 390 degrees Fahrenheit the polystyrene will begin to melt. As it melts it will leak toxic chemicals into the food.

Read on to learn more about polystyrene and why it’s best not to microwave it!

What Is Polystyrene?

Polystyrene is a kind of plastic that can be molded into many different shapes and forms. Because of this, it is used in a wide variety of products with vastly different purposes. Polystyrene is used in automobile parts, gardening equipment, and electrical appliances to name a few general examples.

One common form of polystyrene is known as styrofoam. However, the proper name for styrofoam is expanded polystyrene or extruded polystyrene (aka EPS or XPS). (Styrofoam is a trademarked name for a specific product composed of EPS by a company called Dow Chemical). EPS is valued for its excellent insulative abilities. It’s often used in the food industry as take-out boxes because they’re good at keeping the food fresh. This means that EPS is the form of polystyrene most likely to end up in a microwave.

People might also see polystyrene being used in the form of packing peanuts, egg cartons, and loads of other places where food or other fragile items need to be insulated.

Microwave Safe Polystyrene

Do not cook anything in the microwave on any plastic containers unless they are marked as microwave safe. Even then, it’s often going to be the best choice to just use something else in the microwave. Using glass or paper that has been marked microwave safe is a good idea because those substances are less likely to link the toxic chemicals that polystyrene has.

If they have been marked as microwave safe this means that they have gone through rigorous scientific testing to ensure that this particular product is safe to place in a microwave. However, if someone is just heating something up real quick then the risk is greatly decreased. It takes a little over 30 seconds for the average microwave to heat polystyrene to the point where it would start releasing harmful toxins.

Microwaves themselves are not what makes cooking food in polystyrene a hazardous decision. Anything that heats up the polystyrene to the point of leaking toxins is unsafe. Whether that be cooking with it on a stove, in an oven, or over a campfire. Any and all of these have the potential to overheat the polystyrene and essentially poison the food it’s holding.

Polystyrene is great for insulating foods and helping them maintain their temperature, but it is important not to cook in them no matter the cooking method. There are many other forms of cookware that can be used without endangering the people who are planning to eat the food that is being made. Glass or metal pans for ovens, wrapping food in tinfoil for campfires, and paper or glass or ceramic plates for cooking in a microwave.

What To Do if Ingested

Polystyrene releases the toxic chemical styrene, among other dangerous chemicals, when heated. If ingested, the styrene can lead to neurological damage, increased risk of cancer, and a whole lovely list of other possible side effects. In small infrequent doses, your liver should be able to protect you from most of the toxins. However, with increased ingestion comes increased exposure which leads to increased risks.

There isn’t specifically a way to reverse damage caused by ingesting styrene or any of the other possible leeched chemicals. If it starts to cause symptoms then there are ways to treat those symptoms.

However, if someone ingests polystyrene in its solid form, it can cause choking or intestinal blockage if the piece is large enough. This is due to the body’s inability to break down and absorb the foam. If a person has ingested a larger piece of styrofoam then it is important to follow poison control’s protocol.

The first step is to remove any styrofoam that you can, and most definitely take it out of the person’s hands. Next, wipe out the foam eater’s mouth with a soft wet cloth. Following the cloth, give them at least 2 full glasses of water to drink. This will help dislodge any small bits that may have gotten caught in the esophagus. If any related concerns arise, call poison control or bring them to the hospital if it is an emergency.

Is Polystyrene Reusable?

Polystyrene products, especially those made with expanded polystyrene, are not very reusable. Over time they start to leak styrene, a toxic chemical that has been linked to cancer and other horrendous maladies. If a product made of polystyrene is covered in lots of scratches and cracks, it needs to be thrown away.

Items made from polystyrene are also hard to recycle. This makes them incredibly frustrating for waste management facilities, especially since they’re such common products. Polystyrene is technically recyclable. However, in the case of most polystyrene products, it’s composed of about 95% air. This means that the cost of gathering all the polystyrene and bringing it to the necessary facility capable of breaking it down isn’t going to be worth the cost.

Another frustrating factor is that products made from recycled polystyrene aren’t allowed to come in contact with food. The recycled polystyrene can only be used to produce containers or pack peanuts or other such items that won’t touch food. This is because of the danger of styrene leaking into people’s food. This limit on what can be produced from the recycled material is another factor leading to the cost of recycling polystyrene not being worth the cost.