Most to-go containers from your favorite restaurant are styrofoam. Many leftovers are much better when heated in the oven. What could be easier than heating your leftovers the to-go food containers? A common question when reheating food is can styrofoam go in the oven? The answer is no. Here is everything you need to know about styrofoam and reheating leftovers.

“Floating styrofoam lunch box, rural Baja California, Mexico” by Wonderlane is licensed under CC BY 2.0

Is It Safe To Put Styrofoam In The Oven?

Can styrofoam go in the oven? The answer is no. Made of a hazardous material, when heated styrofoam can discharge carcinogenic chemicals into your food. The heat from the oven can melt the styrofoam vessel.

What Is Styrofoam And What Are Its Uses?

“Tepid in styrofoam” by eatatree is licensed under CC BY-SA 2.0

Styrofoam, “first commercially produced in 1930, is used for a wide range of commercial, packaging, and building purposes. Made of polystyrene foam, styrofoam contains the chemical styrene. In 2012, approximately 32.7 million tons of styrene were produced globally, and in recent years polystyrene has become an ubiquitous household item worldwide. In 1986, the US Environmental Protection Agency (EPA) announced that the polystyrene manufacturing process was the fifth largest source of hazardous waste. Styrene has been linked to adverse health effects in humans, and in 2014, it was listed as a possible carcinogen.” (1)

One of the most common use of styrofoam in households today, especially as it relates to this article, is as a container for take out food from restaurants. It is light weight and cheap to produce making it attractive for restaurants. “Disposable plates and cups are commonly made out of styrofoam because it allows for hot food or drink to remain hot without burning the person holding the cup or plate.” (2)

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Does Styrofoam Melt?

Yes, styrofoam can melt. Styrofoam cannot withstand high heat. The make up of the polystyrene beads start to soften at 212 degree fahrenheit. It will begin to melt at 464 degrees fahrenheit.

What Is The Melting Point of Styrofoam?

Traditional styrofoam melts at 464 degrees Fahrenheit. Though it will melt at this high temperature, styrofoam will begin to soften at a much lower temperature. Keep styrofoam away from heat to avoid toxic fumes, hazardous chemicals, and a mess to clean up.

What Temperature Does Styrofoam Leach?

What is leaching? In layman’s terms, leaching is when materials are combined after the introduction of a liquid. This can occur with soil when minerals from the soil combine when rainwater is added. In the case of this article, I wanted to research whether hot liquids, food, or the heating of liquid or food will cause the toxic chemicals from the Polystyrene to leach or transfer into what you will then eat or drink. Though thorough research, I found experiments on leaching was done on the following Polystyrene products: coffee cups lids, stir sticks, spoons, EPS cups, EPS bowls, and EPS takeout containers.

Leaching experiment results:

“Treatments included coffee in a paper cup with a polystyrene lid, coffee with cream and sugar in a clean glass beaker with a polystyrene stir stick, soup broth in a clean glass beaker with a polystyrene spoon, water, coffee and coffee with cream and sugar in an EPS cup, soup broth in an EPS bowl, and instant gravy in an EPS takeout container. All treatments used 250 mL of liquid except for the paper cup with the polystyrene lid (200 mL of coffee), the EPS takeout container (50 mL of gravy), and the EPS cup with water (200 mL). Leaching trials lasted 30 min—roughly the length of time [one would] expect a person to have food or drink in a polystyrene product. For the paper cup with the polystyrene lid, the cup was tipped every 2 min to simulate drinking and allow the liquid to come in contact with the lid.” (4)

“Other studies that use realistic leaching conditions have found concentrations that do raise concerns for human health. Sanagi et al. (2008) found styrene concentrations ranging from 45 to 293 ppb in water under leaching conditions of 24–80°C for 30 min in a polystyrene cup. Tawfik and Huyghebaert (1998) found styrene concentrations of 24 ppb in whole milk under conditions at 40°C for 24 h and in ice-cream under conditions at −10°C for 30 days in polystyrene cups.” (4)

What Happens If You Put Styrofoam In The Oven?

Styrofoam cannot withstand high heat. As discussed earlier in this article, the high heat of the oven can melt the styrofoam producing harmful chemicals. In addition, the melted polystyrene foam will produce an oily liquid or gooey mass in your oven which can be difficult to clean.

If you have made the mistake of heating styrofoam in your oven, here are some tips to clean it by Hunker.com (2).

Can You Microwave Styrofoam?

We know you cannot put styrofoam in the oven, but can you microwave it? After researching this topic, I found several articles stating you can microwave some types of microwave-safe styrofoam. The vast majority of my research on the topic recommends not using polystyrene containers in the microwave oven to warm food.

Just like with the oven, the higher temperature created by the microwave can cause toxic chemicals from the styrofoam to contaminate your food. If you have microwaved styrofoam in the past, you probably have noticed the bottom of the container melted and the food probably leaked from the vessel in the microwave. Do not assume the container your food is in is microwave-safe. If there is no clear microwave-safe label on the container, transfer food from the take-out containers and place into a glass dish or even a paper plate to warm food.

Why Should I Use Styrofoam Containers?

Styrofoam containers are common for leftover and take out food. You can use the container to store cold food while refrigerated. A styrofoam cup can hold cold liquids, but I do not recommended using it for hot beverages. Though the hot liquid will remain hot longer if the beverage is in a styrofoam cup, I recommend instead using a paper cup.

Safe Materials For Reheating Food In The Oven

“Our 1st food in the oven” by edcleve is licensed under CC BY-NC-ND 2.0

What type of dish should I transfer food into when reheating food in the oven? The following is a list of oven-safe containers that will prove to be a safe option for heating food.

Glass, Oven-Safe Container

Glass, oven-safe containers are a great alternative to using the styrofoam container your leftover food came in. Transfer the food to the glass, oven-safe container which can withstand high heat.

Aluminum Foil

You can place a sheet of aluminum foil directly onto the rack of the oven or use it to line your baking sheets for easy clean up. The melting point of aluminum foil is upwards of 1220 degrees F so there is no worry of this material melting or contaminating your food (3).

Metal Cookie Sheet

For quick and even reheating, using a metal cookie sheet is ideal because there is plenty of room to spread out your leftovers so the heating can occur quickly. Used for baking, metal cookie sheets can withstand high temperatures.

What Container Can I Use To Heat Food In the Microwave?

Whether using the oven or a microwave, it is not recommended to reheat food in styrofoam containers. Instead, remove the food from the styrofoam container and use one of the following types of dishes to reheat food in the microwave:

Glass, Microwave-Safe container

I highly recommend using a glass, microwave-safe container to microwave your food. If the container has a glass lid, leave it on while microwaving to avoid any splatter of the food.

Paper plate

If you are looking to avoid doing dishes, use paper plates to microwave your leftover food. You can transfer the food to the plate. After eating the food, throw the plate away. You may want to cover the plate with a commercially made microwavable food cover. If you do not have one, use paper towels or a coffee filter to cover the food to prevent splatters.

Safe Plastic, Microwave Safe Container

I do not recommend using plastic to microwave your food. Plastic is made of properties which when heated could contaminate your food. There are microwave safe plastics. Look at the recycling mark on the bowl. According to Hunker.com, those numbered 3, 6, and 7 are not safe to microwave. The safest bet is those number 5. (5).

Travel mugs or coffee mugs

Transfer hot drinks or liquids such as coffee or soup to a microwave safe travel mug or coffee mug before heating in the microwave.

Do not use any thing that is made of or decorated with medal in the microwave.

In Summary

Do not heat food in stryofoam. Transfer food from the styrofoam plates, cups, or containers into an oven-safe or microwave safe receptacles to avoid any leaching of toxic materials into your food. There are definitely safer materials to heat your food in!

References:

(1) Farrelly, T., & Shaw, I. (2017, February 01). Polystyrene as hazardous household waste. Retrieved May 12, 2021, from https://www.intechopen.com/books/household-hazardous-waste-management/polystyrene-as-hazardous-household-waste

(2) How to REMOVE MELTED Styrofoam. (n.d.). Retrieved May 14, 2021, from https://www.hunker.com/13421965/how-to-remove-melted-styrofoam

(3) Papiewski, J. (2019, March 02). Melting temperature of aluminum foil. Retrieved May 17, 2021, from https://sciencing.com/melting-temp-aluminum-foil-9207.html

(4)Thaysen, C., Stevack, K., Ruffolo, R., Poirier, D., De Frond, H., DeVera, J., . . . Rochman, C. (2018, February 14). Leachate from expanded polystyrene cups is toxic to aquatic invertebrates (ceriodaphnia dubia). Retrieved May 17, 2021, from https://www.frontiersin.org/articles/10.3389/fmars.2018.00071/full

(5) What are the numbers that say that plastic is safe to use in the microwave oven? (n.d.). Retrieved May 17, 2021, from https://www.hunker.com/12003478/what-are-the-numbers-that-say-that-plastic-is-safe-to-use-in-the-microwave-oven

About the Author:

Hi! I’m Chris. I’m a mother, wife, college professor by trade and micro-influencer by hobby. I am a bargain hunter, jack of all trades, and master of chaos.

Thank you for reading my random thoughts on travel, my stories of life as an under appreciated mother of a teenager, and my easy recipes that have won no awards but instead my family’s love and adoration (which is WAY better, right?).