What is the ingredient in microwave popcorn that is bad for you?

November 10, 2025 •

5 min read

According to a 2019 study, people who frequently eat microwave popcorn have significantly higher levels of PFAS chemicals in their blood. The primary ingredients in microwave popcorn that have caused health concerns are diacetyl, a buttery flavoring, and per- and polyfluoroalkyl substances (PFAS), a chemical found in the bag lining.

Quick Summary

This article explores the health risks associated with diacetyl and PFAS, the chemicals once or currently used in microwave popcorn production and packaging. It outlines the health concerns related to inhalation and ingestion of these substances and provides safer alternatives for enjoying your favorite snack.

Key Points

Diacetyl was linked to "popcorn lung": The buttery flavoring, diacetyl, caused severe lung disease in factory workers who inhaled high concentrations.
PFAS chemicals were in the bags: "Forever chemicals" known as PFAS were used to grease-proof microwave popcorn bags and were found to transfer to the food.
PFAS linked to health problems: Exposure to PFAS is associated with increased cholesterol, hormonal disruption, developmental issues, and a higher risk of certain cancers.
Many brands have removed these chemicals: Following public concern, many major manufacturers eliminated diacetyl and PFAS from their products, but some alternatives may also carry risks.
Homemade popcorn is the safest option: Making your own popcorn in a paper bag in the microwave, on the stovetop, or in an air popper allows for complete control over ingredients, avoiding problematic additives and packaging.
Moderation and label reading are key: If buying commercial microwave popcorn, read the ingredients list carefully and consume in moderation to minimize potential risks.

For years, the warm, buttery smell of microwave popcorn has been a movie night staple. However, over the last two decades, this convenience food has come under scrutiny due to some concerning ingredients used in its production. While the popcorn kernel itself is a healthy whole grain, the real issues often lie in the added chemicals and the packaging. The primary culprits are diacetyl, a buttery flavor enhancer, and per- and polyfluoroalkyl substances (PFAS), used to make the bags grease-proof.

The Story of Diacetyl and "Popcorn Lung"

Diacetyl (also known as 2,3-butanedione) is an organic compound that gives many foods, including some microwave popcorn, its distinctive buttery flavor. The health risks of diacetyl became widely publicized in the early 2000s, leading to the term "popcorn lung." This was not an issue with eating popcorn, but rather the inhalation of large amounts of diacetyl vapor, particularly by workers in popcorn manufacturing plants.

What is Popcorn Lung?

"Popcorn lung" is the popular name for bronchiolitis obliterans, a severe and irreversible lung disease. The disease is caused by inflammation and permanent scarring that narrows the smallest airways in the lungs. Symptoms often include a dry cough, wheezing, and shortness of breath that worsens over time. While the risk from occasional home use is much lower than for factory workers, the publicity surrounding the danger led many major popcorn manufacturers to remove diacetyl from their products by 2007. Some companies replaced it with similar, but potentially also dangerous, chemicals like 2,3-pentanedione, though many have since removed these as well.

The Threat of "Forever Chemicals" in the Bag: PFAS

Beyond the flavorings, the packaging of microwave popcorn has also contained a hazardous component: per- and polyfluoroalkyl substances, or PFAS. These are a group of synthetic chemicals, sometimes called "forever chemicals" because they are highly persistent in both the environment and the human body.

Manufacturers used PFAS to create the grease-proof coating on the inside of microwave popcorn bags, preventing oil from leaking through. However, when heated, these chemicals can migrate from the bag into the popcorn itself. A 2019 study showed that regular consumers of microwave popcorn have significantly higher levels of PFAS in their blood. The FDA announced in 2024 that PFAS are no longer used in food packaging like popcorn bags in the US, but previous exposure and other international products may still pose a risk.

Health Risks of PFAS Exposure

Exposure to PFAS has been linked to a range of potential health problems:

Increased cholesterol levels: Studies have found associations between higher PFAS blood levels and elevated cholesterol.
Reproductive and developmental issues: PFAS exposure has been associated with decreased fertility, reduced birth weight, and other developmental effects.
Hormonal disruption: These chemicals are known as endocrine disruptors, potentially affecting thyroid function and other hormones.
Weakened immune system: Some studies show a link to reduced vaccine effectiveness and other immune system issues.
Increased cancer risk: Associations with kidney and testicular cancer have been found in research.

Comparing Commercial Microwave Popcorn to Homemade Options


Feature	Commercial Microwave Popcorn	Homemade Microwave Popcorn (paper bag)	Stovetop Popcorn	Air-Popped Popcorn
Bag Chemicals (PFAS)	Historically contained PFAS in bags; many now advertise as free, but read labels.	Requires using a standard brown paper lunch bag, avoiding chemical linings.	No bag chemicals involved.	No bag chemicals involved.
Flavoring (Diacetyl)	Many major brands removed this, but not all. Alternatives may still be used.	You control all ingredients; use natural flavors like butter or nutritional yeast.	You control all ingredients and seasonings.	You control all ingredients and seasonings.
Fat Content	Often contains unhealthy fats like partially hydrogenated oils.	Use a healthy oil like coconut or olive oil, and control the amount.	Use a healthy oil and control the amount.	Requires no oil, making it the lowest-fat option.
Sodium Content	Typically very high in sodium.	You control the amount of salt added.	You control the amount of salt added.	You control the amount of salt added.
Convenience	Very high convenience, just pop and serve.	High convenience, slightly more prep than commercial versions.	Requires slightly more time and monitoring.	Requires an air popper machine.

Making Your Own Healthy Microwave Popcorn

For those who enjoy the convenience of the microwave but want to avoid unnecessary chemicals, making your own is simple. You only need popcorn kernels, a paper bag, and a few minutes.

Here are the steps:

Start with the basics: Put about 1/4 cup of plain, non-GMO popcorn kernels into a plain brown paper lunch bag.
Add your oil (optional): For added flavor, you can toss the kernels with a small amount of healthy oil like coconut or olive oil before placing them in the bag.
Seal the bag securely: Fold the top of the paper bag over two or three times to ensure it stays closed during popping.
Microwave with care: Place the bag in the microwave and cook on high for 2-3 minutes. Listen carefully and stop the microwave when the pops slow down to about one every two seconds to prevent burning.
Season to your liking: Once cooked, you can add melted butter, salt, nutritional yeast for a cheesy flavor, or other seasonings of your choice.

Conclusion

The health concerns surrounding certain ingredients in microwave popcorn, namely the artificial butter flavoring diacetyl and the "forever chemicals" known as PFAS in the packaging, have led to significant changes in the industry. While many major brands have removed these harmful substances, it is still crucial for consumers to read labels and be aware of potential risks. The most direct way to eliminate concerns is to make popcorn from scratch, either on the stovetop, in an air popper, or in a simple paper bag in the microwave. This gives you complete control over the ingredients, ensuring a safe and delicious snack for you and your family. For further information on minimizing chemical exposure in your diet, consider consulting resources from reputable health organizations.

Sources

Verywell Health: Is Microwave Popcorn Bad For You? - Cancer
Medical News Today: Does microwave popcorn cause cancer? What to know
UCLA Health: Eating microwave popcorn increases the level of PFAS in body
Allrecipes: Microwave Popcorn Recipe

Frequently Asked Questions

Diacetyl is a chemical compound that provides a buttery flavor and aroma. It was used in many food products, including microwave popcorn, to enhance the buttery taste. Health concerns arose when factory workers inhaling large amounts of the vapor developed a rare lung disease called bronchiolitis obliterans, or "popcorn lung".

Historically, microwave popcorn bags were lined with per- and polyfluoroalkyl substances (PFAS) to make them grease-proof. In 2024, the FDA announced that PFAS are no longer used in food packaging in the US, but it's always wise to check product packaging and consider older products.

PFAS have been linked to several health concerns, including an increased risk of certain cancers (kidney, testicular), elevated cholesterol, hormonal imbalances, a weakened immune system, and developmental problems.

After the diacetyl scare, some manufacturers initially used similar chemicals like 2,3-pentanedione. However, studies suggested these alternatives might also pose respiratory risks, leading some companies to find safer solutions or discontinue artificial flavorings.

While the overall risk from occasional consumption is low compared to occupational exposure, the chemicals can persist in the environment and the body over time. For minimal risk, it is recommended to opt for brands that have removed these ingredients or make popcorn from scratch.

For the healthiest option, an air-popper is best, as it uses no oil. However, making your own microwave popcorn in a brown paper bag with plain kernels and controlling the oil and salt is also a very healthy alternative to commercial brands.

While some chemicals associated with microwave popcorn, like PFAS, have been linked to cancer risks in studies, particularly with high-level exposure, the American Cancer Society states that there is no strong evidence linking typical consumption of microwave popcorn to cancer. Choosing safer, homemade options eliminates this potential risk.