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However, polystyrene is a different type of foam that makes up some disposable food containers and is not always safe to microwave. Due to health and safety concerns, some types of food and drink containers are more suitable than others for microwaving. This article discusses polystyrene foam containers in more detail and whether they are safe to microwave. It also provides tips for safely heating food and answers common questions about heating food containers. What is Styrofoam Share on PinterestShea Evans/OffsetStyrofoam is a brand of a particular type of foam that the building industry commonly uses in insulation and construction. Some people in countries such as Canada and the United States often use the term when referring to disposable takeout containers, packaging peanuts, and disposable coffee cups. However, these items consist of a type of polystyrene foam that manufacturers inject into molds to set in shape. The full name for this material is expanded polystyrene (EPS) foam. EPS foam is a popular material for food and drink containers, as it is light and cheap to produce. It also acts as an insulator to keep food and beverages warm. However, cities in the United States — including Seattle and San Francisco — have begun to ban EPS containers in favor of more environmentally friendly options. EPS foam does not decompose easily, and it is difficult to recycle. Animals may mistake the material for food and eat it, which can harm their health. Similarly, particles that end up in the ocean can negatively affect marine life. Some scientists are also concerned that EPS foam, which contains a compound called styrene, may be carcinogenic or cancer-causing. Studies have linked the substance to incidences of cancer in both humans and other animals. For more science-backed resources on the environment and sustainability, visit our dedicated hub. Is it safe to microwave Styrofoam It may not be safe to microwave EPS foam containers unless they have a label showing they are microwave-safe. The Food and Drug Administration (FDA) regulates plastic and polystyrene containers, plates, and cups and performs tests on their safety, including their use in microwaves. FDA-approved EPS containers should have microwave-safe labels to show they have been tested and are safe for use in microwaves. Unless an EPS product displays this label, it may not be safe to microwave. Research shows that heating may cause substances in the EPS to leak, or migrate, into the food inside the container. While the concentrations of substances that leak may not be large enough to cause harm in most typical situations, many factors may influence the safety outcomes, including:fat content in the foodtype of foodtemperatures for heatingstorage conditions of the containerslength of time heating Additionally, some EPS foam containers may crack or lose structural integrity if someone heats them. This may cause hot foods or beverages to leak out and cause burns. One substance that may transfer from the EPS foam container to the food inside is of particular concern to researchers. Styrene, which is a compound in EPS foam, has links to cancer. According to the Centers for Disease Prevention and Control (CDC), high levels of styrene may affect a person’s nervous system and is a possible human carcinogen. Human studies on the association between styrene and certain cancers often focus on long-term exposure, usually in people who regularly work with the substance. Therefore, although there is a proven connection between occupational exposure to styrene and cancer, the results may not directly apply to styrene from microwaved EPS foam food or beverage containers:A long-term 2017 study found that people exposed to styrene through work over a long period of time may be at higher risk of developing myeloid leukemia, Hodgkin lymphoma, and cancer of sinuses and nasal cavities.A 2018 study found that people who work with plastics may be at higher risk of developing acute myeloid leukemia after about 15 years of exposure to styrene.A 2019 study found that workers exposed to styrene may be at increased risk of mortality from non-Hodgkin lymphoma, pancreatic, and esophageal cancer. However, a 2017 systematic review found no strong link between styrene exposure and certain types of cancer. Therefore, further research into this topic may be needed. Tips for safely heating food containers People may consider trying the following tips to ensure they are heating food containers safely: heating an EPS foam container only if the product has a microwave-safe labeltransferring food or beverages to microwave-safe containers made from Pyrex, ceramic, or glassventing the microwave-safe EPS foam container to prevent pressure from building inside itrefraining from using old or damaged EPS containers, which may leak substancesusing oven gloves, mittens, or a protective material when removing a heated container from the microwaveavoiding the microwave and transferring food to a pot or pan to heat on the stovetop or in the oven Frequently asked questions Below are some common questions and answers about heating food containers. What should you not put in the microwave A person should avoid putting items in the microwave that can melt, release toxic fumes, or cause a fire. These include:plastic containersaluminum foilmetal containers or cutleryinsulated coffee cups, bottles, or flasksbrown paper bags Can Styrofoam go in the oven Individuals should not put EPS foam in the oven. The material may warp and soften at very high temperatures. Heating the EPS foam in the oven may also release harmful substances into the food, similar to the microwave. Can you microwave a plastic bowl People should not heat plastic bowls in the microwave unless they have a microwave-safe label. Summary A person should only heat food in an EPS foam container in a microwave if the container has a microwave-safe label. Microwaving EPS foam that is not microwave-safe can potentially cause the carcinogenic substance styrene to seep into the food. The container may also crack or soften, and hot food may leak. To ensure safety, a person should transfer food to a glass, ceramic, or Pyrex container before heating. Last medically reviewed on July 21, 2022Nutrition / DietEnvironment / Water / PollutionEnvironment/Sustainability 14 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Axelsson, C., et al. (2017). Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events.https://pubmed.ncbi.nlm.nih.gov/28755809CFR - code of federal regulations title 21. (2022).https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=177.1640Christensen, M. S., et al. (2017). Cancer incidence in workers exposed to styrene in the Danish-reinforced plastics industry, 1968–2012.https://journals.lww.com/epidem/Fulltext/2017/03000/Cancer_Incidence_in_Workers_Exposed_to_Styrene_in.20.aspxChristensen, M. S., et al. (2018). Styrene exposure and risk of lymphohematopoietic malignancies in 73,036 reinforced plastics workers.https://journals.lww.com/epidem/Abstract/2018/05000/Styrene_Exposure_and_Risk_of_Lymphohematopoietic.4.aspxCollins, J. J., et al. (2018). A systematic review of epidemiologic studies of styrene and cancer.https://www.tandfonline.com/doi/full/10.1080/10408444.2018.1445700Food service packaging requirements. (2022).https://www.seattle.gov/utilities/your-services/collection-and-disposal/food-and-yard/business-and-commercial-compostables/food-packaging-requirementsGuazzotti, V., et al. (2022). Migration testing of GPPS and HIPS polymers: Swelling effect caused by food simulants compared to real foods.https://www.mdpi.com/1420-3049/27/3/823/htmHwang, J., et al. (2020). Potential toxicity of polystyrene microplastic particles.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7193629Loomis, D., et al. (2019). Cancer mortality in an international cohort of reinforced plastics workers exposed to styrene: A reanalysis.https://oem.bmj.com/content/76/3/157Marten, B., et al. (2018). Expanded polystyrene life cycle analysis literature review: an analysis for different disposal scenarios.https://www.liebertpub.com/doi/full/10.1089/sus.2017.0015Should I put plastic containers in the microwave? (n.d.).https://cancer.ca/en/cancer-information/reduce-your-risk/myths-and-controversies/should-i-put-plastic-containers-in-the-microwaveSmith, M., et al. (2018). Microplastics in seafood and the implications for human health.https://link.springer.com/article/10.1007/s40572-018-0206-zStyrene – toxFAQs. (2012).https://www.atsdr.cdc.gov/toxfaqs/tfacts53.pdfWhat is Styrofoam (2022).https://www.dupont.com/building/styrofoam-is-not-a-cup.htmlFEEDBACK:Medically reviewed by Sade Meeks, MS, RD, Nutrition — By Caitlin Geng on July 21, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageWhat do we know about microplastics in food? How harmful are microplastics in food, and what can we do to mitigate the health risks? In this Honest Nutrition feature, Medical News Today…READ MOREHow can we reduce our exposure to potentially harmful aluminum? A new study from Germany suggests that many people have an overly high intake of aluminum compounds. 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