Can You Microwave Styrofoam? Safety Tips & Guidelines

Microwaves have been around for decades and are known for making kitchen work — namely heating food — much simpler than in the past.

However, due to health concerns, you may wonder what types of containers are best when microwaving your foods and beverages.

This article reviews whether you can microwave styrofoam, if doing so is safe, and what precautions you can take.

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What is styrofoam?

Styrofoam is a term that The Dow Chemical Company trademarks. It refers to a polystyrene foam commonly used in the building industry.

However, in some countries, such as the United States and Canada, the term is often incorrectly used to refer to expanded polystyrene foam injected into molds to make disposable take-out containers, plates, coffee cups, and packaging peanuts.

These containers are popular because they’re cheap and act as good insulators, meaning they keep foods and beverages warm.

Though polystyrene containers were popular in the past, they have slowly been banned in several cities in the United States, such as San Francisco and Seattle, due to environmental and potential health concerns.

Environmentally, the containers do not decompose easily and are difficult to recycle. Also, animals may mistake them for food and eat them.

From a health perspective, they contain a compound called styrene, which has raised some concern, as it has been linked to cancers in animal and human studies.

Summary: Styrofoam is incorrectly used to refer to polystyrene foam containers that are commonly used to serve warm beverages and food.

Can you microwave styrofoam?

There is some concern about microwaving polystyrene foam containers.

One key reason is that they contain a compound called styrene, which human and animal studies have linked to cancer.

In addition, when foods or beverages are microwaved in containers made from polystyrene or plastic, substances used in manufacturing may leak into the food. This especially applies to fatty foods, such as meats and cheeses.

However, it’s important to note that the Food and Drug Administration (FDA) regulates plastic and polystyrene containers, cups, and plates and tests their safety and use in microwave ovens.

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That means any polystyrene or plastic products with a microwave-safe label have been tested for safety in the microwave.

On the other hand, avoid microwaving food in polystyrene containers not labeled as microwave safe, as their safety is not assured. This precaution is not specific to microwaves and applies to other heating methods.

Summary: You can microwave foods or beverages in polystyrene-labeled microwave-safe containers. Conversely, avoid putting polystyrene containers without microwave-safe labels in the microwave.

How to safely heat food

If you are concerned about heating food in a polystyrene container, here are some tips to help you microwave food safely:

Use a microwave-safe container. If you use a styrofoam container, check if it has a microwave-safe label.
Transfer food to ceramic or glass before microwaving. Alternatively, transfer the food into a ceramic, glass, or Pyrex container before heating.
Use the stove or an oven. Another way to avoid potential risks is to transfer the food into a pot or pan to heat on the stovetop or into a baking tray in the oven.
Check for scratches or cracks. Polystyrene and old plastic containers that have scratches or cracks should be disposed of, as they may leach potentially harmful chemicals.
Vent the container before heating it. This prevents pressure from forming, causing the food inside the container to explode.
Carefully remove the container. Use mittens or gloves to remove the container after heating to avoid burning your hands.

Summary: The above tips may help you safely microwave or reheat your food. When microwaving, always use containers that are labeled safe for such use.