Last updated on May 2, 2023.

In Part 1 of this series, I introduced polystyrene, which we commonly refer to as Styrofoam, food packaging. This type of plastic is terrible for the environment and human health. Today, we’ll look at the toxicity of polystyrene in depth.

After watching friends and coworkers repeatedly reheat their take-out and leftovers in polystyrene, I decided to write an article about it. I had known polystyrene was potentially toxic for a long time, but I had no idea just how toxic it is.

Chemicals Leach from Containers into Food

Polystyrene leaches styrene and benzene, chemicals that have known toxic properties, into food. In testing, one scientific journal independently tested and found that polystyrene leaches more toxins when in contact with high-temperature contents and into foods with higher fat content.¹ That means that if you buy hot food, fatty food, soup, or coffee and it is packaged in polystyrene, some of the chemicals from the container leach into your food. Over time, these chemicals can cause severe health problems.

“Styrene is likely to leach when it comes in contact with fatty foods, hot beverages, and especially alcohol. When thinking about the kinds of foods that typically end up in Styrofoam containers (fatty foods) and cups (hot coffee), it seems as though the exact kinds of items Styrofoam contains are exactly the kind of items it should never touch.” -The Green Dining Alliance²

Known Toxicity

When I searched “polystyrene human health” I got more than 13 million results. After reading many articles, I realized that all organizations and even the U.S. government, including the Environmental Protection Agency (EPA), know that polystyrene is harmful to human health as well as land and marine environments. Furthermore, the Food and Drug Administration (FDA) permits the migration of styrene from packaging into food!

Study after study shows that chemicals from polystyrene leach into foods and beverages, especially with higher temperatures and food with higher fat content. And study after study shows that styrene is dangerous to human health. In fact, most agencies caution against the use of polystyrene because of the known health hazards, including these:

• • • • The Environmental Protection Agency (EPA)
      • The World Health Organization (WHO)
      • The International Agency for Research on Cancer
      • National Institute for Environmental Health Sciences
      • U.S. Department of Health and Human Services (DHHS)
      • National Research Council (NRC)
      • Occupational Safety and Health Administration (OSHA)
      • National Institute for Occupational Safety and Health
      • The Agency for Toxic Substances & Disease Registry (ATSDR), Center for Disease Control and Prevention (CDC)

A Known Carcinogen

Styrene exposure increases the risk of leukemia and lymphoma and is a neurotoxin. This alone is enough reason to avoid polystyrene containers. In 2018, the World Health Organization (WHO) reclassified styrene as a probable carcinogen.³ While the EPA does not classify it as a carcinogen, it noted that animal cancer studies provided evidence for carcinogenicity.⁴ Several of the organizations mentioned above, including the International Agency for Research on Cancer and the Department of Health and Human Services, consider it to be carcinogenic.

Hormone Disruption

There are countless studies that show certain types of plastics contain known hormone disruptors. Those chemicals often mimic estrogen and they seep into food and beverages (including breastmilk). In 2014, Environmental Health tested 11 samples of polystyrene and consistently found estrogen seepage after exposure to intense steam or ultraviolet rays.⁵ Since polystyrene is a type of plastic, this is just one more reason to avoid polystyrene containers.

It is terrifying that many schools use foam trays for cafeteria food. Hormone disruption in young children prevents them from developing normally, can affect their ability to reproduce as adults, and can set them up to be prone to other diseases.

Other Health Hazards

Styrene exposure can come from other sources, such as photocopier toner, automobile exhaust, and plastics manufacturing. Exposure can cause irritation of the skin, eyes, mucous membranes, the upper respiratory tract, and gastrointestinal irritation. Chronic exposure can cause neurological problems such as depression, headaches, fatigue, weakness, hearing loss, and disrupted kidney function.⁶

Additional Unknown Chemicals

There are many chemicals and ingredients that are not tested for and not regulated by the EPA and FDA. While this may seem surprising, the standard operating procedure in the United States is to allow a chemical to be used until a known hazard is not only discovered, but proven. Essentially, chemicals are innocent until proven guilty.

Exposure through Manufacturing

Anyone who lives near or works in polystyrene manufacturing sites is at risk of even greater health problems due to respiratory exposure. The Clean Water Action organization noted that “occupational exposure to Styrene increases [the] risk of lymphoma, leukemia, lung tumors, pancreatic cancer, urinary bladder cancer, prostate cancer, and colorectal cancer. High rates of neurotoxicological effects have been reported in workers,” as well as decreased sperm counts.⁷ These plants also emit a toxic and volatile gas called pentane, often used as a blowing agent in the production of polystyrene. 

“Over fifty chemical byproducts are released during the manufacturing of polystyrene, contaminating the air, water and communities that live near these facilities.” –Children’s Environmental Health Network⁸

What You Can Do

Polystyrene is toxic to human health. When ordering take-out, ask the restaurant if they use “Styrofoam” or polystyrene containers. If they do, you can ask if they have an alternative type of container or you can decide to order from somewhere else. When bringing leftovers home from a restaurant, keep a glass or metal container in your car specifically for such occasions. Bring your own reusable coffee mug to coffee shops. As I mentioned at the beginning of my article, try to avoid eating food in polystyrene, and definitely stop reheating your food in polystyrene containers in the microwave. 

Last, polystyrene is the most common type of #6 plastic and is largely not recyclable because of food contamination. In Part 3, I will cover the problems with recycling and the environmental damage polystyrene causes. Thank you for reading, and please share and subscribe!

 

Additional Resources:

“Styrene,” Report on Carcinogens, 14th Edition, National Toxicology Program, Department of Health and Human Services.

Report, “What’s the Package? Unveiling the Toxic Secrets of Food and Beverage Packaging,” Clean Water Action and Clean Water Fund, August 2016.

Article, “Leaching of styrene and other aromatic compounds in drinking water from PS bottles,” by Maqbool Ahmad and Ahmad S. Bajahlan, Journal of Environmental Sciences, 19 (2007), p. 421–426, accessed September 12, 2021.

Footnotes:

1. Article, “Leachate From Expanded Polystyrene Cups Is Toxic to Aquatic Invertebrates,” Frontiers in Marine Science, 28 February 2018.
2. Article, “The Real Cost of Styrofoam,” Green Dining Alliance.
3. Press release, “World Health Organization finds increased cancer risk for chemical found in plastics,” U.S. PIRG, 1 June 2018.
4. Report, “Styrene,” Environmental Protection Agency.
5. Article, “That Takeout Coffee Cup May Be Messing With Your Hormones,” Mother Jones, December 1, 2014.
6. Report, “Styrene,” Environmental Protection Agency, updated May 2020.
7. Fact sheet, “Facts about Styrofoam Litter,” Clean Water Action California, September 18, 2018.
8. FAQs, “FAQs: Polystyrene Foam,” Children’s Environmental Health Network, accessed May 2, 2023.