The Controversial Chemicals Behind Your 'Butter' Flavored Popcorn

A movie night at home with a big bowl of popcorn is a popular way to spend an evening. However, popcorn is more than just a movie snack. Some people use popcorn as a crust for fried chicken, sweet and salty pretzel sticks, sports bars, and other treats. If you're snacking on too much microwave popcorn, though, you could be exposing yourself to dangerous chemicals. 

At the beginning of this century, microwave popcorn factory employees were getting what has been nicknamed "popcorn lung." This is a serious disease that causes irreversible scarring in the lungs, resulting in coughing, shortness of breath, and wheezing. It was determined that breathing in diacetyl — the butter-tasting chemical being used on the popcorn — was the cause. As a result, several manufacturers of at-home popcorn were removing it from their products by 2007 and substituting it with acetyl propionyl (2,3 pentanedione). This substitute, however, has been shown to cause severe respiratory tract injury when inhaled as well.

Diacetyl and acetyl propionyl are controversial because, even though they cause serious health consequences when inhaled, they're "generally recognized as safe" to eat by the FDA (per the National Institute for Occupational Safety and Health). That's because both are naturally occurring chemicals in foods and chemical reactions during baking. Because of that, they're still used in manufactured foods. Meanwhile, NIOSH recommends limiting worker exposure to 5 parts per billion for diacetyl and 9.3 parts per billion for acetyl propionyl over an eight-hour shift.

On top of that, per- and polyfluoroalkyl substances (PFAS), which are referred to as forever chemicals, are used in paper products (among other things), including microwave popcorn bags. PFAS transfer into the oil on the popcorn, so people end up consuming it. Since the chemicals dissolve in water and break down at a snail's pace, they linger and accumulate in the environment and tissues.

While these chemicals are present in human blood and tissues, a study published in Environmental Health Perspectives in 2019 found that those who regularly eat microwave popcorn have significantly more of it in their bodies. In fact, research participants who snacked on popcorn every day for a year had up to 63% higher serum levels.

The problem is that PFAS have harmful effects, such as increased cancer risk, decreased fertility, hampered immune system, high cholesterol, and higher obesity risk. Although more research is needed, exposure to these chemicals could have even more and potentially worse health consequences depending on the level of toxicity.

Unfortunately, the use of diacetyl, acetyl propionyl, and PFAS isn't limited to microwave popcorn. Diacetyl and acetyl propionyl naturally occur in foods like baked goods, butter, cocoa, coffee, dairy products, honey, and some fruits and vegetables. The chemicals are also found in beer and wine because they're byproducts of fermentation.

While consuming them is generally considered safe, they pose great inhalation risk when they're used in products like cooking oil spray and become airborne. In fact, a jury awarded $25 million in February 2026 to a man who sued Conagra Brands in 2020. He claimed exposure to diacetyl, acetyl propionyl, and similar hazardous chemicals while using Pam since 1993, which caused severe respiratory system damage and other lung issues. Although Conagra said it removed diacetyl from the product in 2009, it couldn't produce sufficient evidence.

Meanwhile, PFAS are in more than microwave popcorn bags. These chemicals are used to make the wrappers for all kinds of foods, including the wrappings used for fast food and the boxes used to deliver pizza. They can also end up in food after you cook it if you still use nonstick cookware made with the chemicals. That's why several states are prohibiting the distribution and sale of products that contain PFAS, starting as early as 2028 — although some companies have already stopped using them.

However, PFAS also end up in the air, soil, and water around manufacturing facilities and landfills — one of the effects of chemical pollution. Fish and produce in those areas become contaminated as a result, making it very difficult to avoid the chemicals altogether.