Is It Safe to Microwave Food in Styrofoam? Everything You Need to Know

The Ultimate Safety Guide for Reheating Takeout

When you look at a white foam takeaway container, do you have the question of “Is it safe putting your food in a Styrofoam container and then microwaving it?” Many people wonder if these materials are safe for heating or re-heating food . Moving the food from one location to another can also create added work for inadequate microwaving. The reason why “heating” seems easy is because you are only zapping the food. However, there may be adverse chemicals within the container that could potentially leach into your food as well.

This guide will give an in-depth insight into the material polystyrene, the potential dangers associated with sterile leeching . It will show you how to tell if a container is suitable for microwaves.

Understanding Polystyrene and Food Packaging

Although many individuals refer to foam cups or food trays as Styrofoam, in fact, Styrofoam is a registered trademark of DuPont. It is used for insulating your home against heat loss during cold weather. What is commonly referred to as “Styrofoam” when you’re using that material for take-away food is actually called expanded polystyrene (EPS) foam. EPS foam is a plastic material that can be identified with the recycle symbol #6 on your take-away container. EPS foam is composed of hundreds of thousands of repeating units of styrene. This is a chemical that’s linked together to make plastics from long-chain polymers. EPS foam has excellent insulating properties. It does a great job of maintaining the heat of the coffee you drink in your coffee cup and the coolness of the ice cream that you consume from your ice cream container . It provides extreme localized heat generated by a microwave.

Why Heat and Polystyrene Don’t Mix

Microwaves provide heat through agitation of the water molecules present in the food that is being cooked. Cooking fatty or oily foods will heat them above the boiling point of water, i.e., 212 ° Fahrenheit .

Many things happen to standard EPS foam when exposed to such high temperatures:

• Melting and Destruction: When EPS foam is subjected to high heat, it begins to lose its firmness and structural integrity. Often, it results in “hot spots” due to the melting of the container into the food.
• Migration of Chemicals: When the foam degrades, it causes the monomers , polymer’s building blocks, i.e., styrene etc, to break away from the polymer chain and migrate into the food.
• Leaching in Oily Foods: Oily foods will dissolve chemical residue from plastic much more quickly than non-oily foods. It makes heating oily food in a foam container the most dangerous action.

Is Microwaving Styrofoam Linked to Cancer?

The primary concern with heating polystyrene is styrene. The National Toxicology Program has classified styrene as “reasonably anticipated to be a human carcinogen”.

Potential Health Effects of Styrene Exposure

Although styrene leaches only a small amount after a single 30-second reheat, experts caution about cumulative amounts of styrene exposure. The potential hazards include the following:

• White Carbon Poisoning: Long-term exposure has been associated with increased white blood cell counts. They increase the chances of developing leukaemia and lymphoma.
• White Blood Cell Disorders: Long-term exposure has been associated with various types of white blood cell disorders, such as Chronic Lymphocytic Leukaemia.
• Hormone Disruption: Some studies indicate that certain types of styrene-containing products may mimic hormones, and interfere with healthy reproductive systems.

Decoding the Symbols on Your Takeout Box

Believe it or not, there are certain types of polystyrene containers that can withstand microwaving. The U.S. Food & Drug Administration (FDA) regulates materials that come into contact with food and has rigorous testing requirements.

What to Look For

To verify if your container is microwave safe before cooking, please check for the following signals on the bottom side of the container:

• Microwave symbol – A small microwave looking symbol with waves coming out of the microwave image.
• Wavy lines – Three rows of horizontal lines tell you the container has been tested for heat-resistant material.
• Written text – Look for the words “Microwave Safe” stamped into the plastic.
• Recycling code #5 (PP) – If your container is made of a hard material rather than foam and has a #5 on the bottom, it is made out of polypropylene (PP). It is one of the safest plastics to use in the microwave.
• IMPORTANT NOTE: Don’t use containers without microwave-safe symbols, even if they have a #6 PS recycle code.

The Safest Containers for Reheating

If you’re looking to eliminate chemical leaching risk, then your current food storage method is no longer acceptable. These products would provide the gold standard alternative.

• Glass and Pyrex – These are truly the gold standard. They simply do not leach any chemicals as they are a non-porous material.
• Ceramic – Almost all ceramic plates and bowls are safe. However, be cautious of any cookware with metallic trim.
• Silicone – Food-grade silicone has excellent heat stability. It is a great option for microwave lids & collapsible containers.
• Eco-Friendly Alternatives – Many new restaurants are now starting to use sugarcane bagasse or wheat straw plates. These materials are biodegradable and can go in the microwave as well.

Why Many Cities Are Banning Foam

Food safety is not just an issue; so too is the environment. Polystyrene foam containers present serious problems for both.

• Foam is Non-Biodegradable: Foamed plastic containers can take over 500 years or longer to decompose in a landfill.
• Marine Pollution: Due to their light weight and ability to break into small pieces, foamed containers easily find their way into the water. They are often mistaken for food by marine life.
• Recycling Challenges: Although foamed plastic is technically recyclable, few municipal programs accept expanded polystyrene foam products. They are bulky and contaminated with food.

These three facts were significant enough for Seattle and San Francisco to have developed foam container bans.

Best Practices to Reduce Chemical Exposure

When using containers that you don’t know if they’re safe or not, take these precautions:

• Move the Leftovers:- Whenever you can, place your leftovers into glass or ceramic containers.
• Don’t use Plastic For Oily Foods:- You can add heat to large amounts of oily foods. This would cause a lot of heat in the plastic and therefore can have a chance of melting the plastic.
• Leave Jar Unpressed For Microwave:- If you are using a container that states that it’s microwave-safe, be sure to leave the lid ajar . Steam can escape and create a pressure buildup.
• Disposing of Scratched or Stained Plastic Containers:- If you have many scratches, dendrites, or staining, throw away the container.

The more damage done to the plastic will increase the risk of it leaching food.

Final Verdict: Play It Safe with Your Leftovers

Although the FDA permits some “microwave-safe” polystyrene containers, most takeout containers made from foam are not appropriate for microwave use. It is obvious that the risk of chemical leaching and melting or the potential for adverse long-term health effects . It includes the possibility of developing cancer. You should always take ten seconds to place your food on a different dish before hitting the “Start” button on your microwave.

The Golden Rule: When uncertain, put food into glass.