November 8, 2007 The Pump Handle 3Comment

The long awaited EPA study of chemicals emitted when microwave popcorn is popped has just been published. Its results are not surprising: popping microwave butter flavor popcorn releases a sizable number of chemicals into the air, although not necessarily in large amounts. These chemicals include diacetyl, the primary chemical implicated in the bronchiolitis obliterans (“popcorn lung”) cases seen in popcorn and flavor factories.

The study does not attempt to measure or model the exposure consumers get when they pop microwave popcorn at home. Rather, it simply measures what chemicals are emitted when you pop the stuff, and when you open the bags.

Why did the EPA insist on not sharing these results with anyone (including OSHA) before publication?

The results of the study were fairly predictable. With one exception (methyl ethyl ketone) the same chemicals found in the popcorn factories were emitted from the sampled microwave popcorn bags. The greatest emissions (and 80% of the total) come when you open the bag (not while the bag is being microwaved), and emissions drop off dramatically but continue at low levels for some minutes after opening.

There was a sizable variation between brands and types of popcorn popped. For most brands, popping the butter flavor samples resulted in more diacetyl emissions than popping the “light” samples, but not for all.

What does this tell consumers about the hazards of breathing artificial butter vapors from popcorn microwaved at home? Not much. We have already have exposure (rather than emission) data from the case of the Colorado man who popped and ate two bags of heavy butter microwave popcorn a day and developed popcorn lung. The exposure levels in his home were 0.5-3 parts per million after he popped the bags. This is comparable to levels in popcorn factories and evidently enough to damage his lungs.

The EPA scientists also measured the flourotelemers that are released in the popping. These are chemicals used in the lining of the bags, to keep the oils from seeping out. There is evidence that the body can convert flourotelemers into PFOA, a chemical considered by some scientists to be a likely carcinogen. (For more about PFOA, see this case study at

The Project on Scientific Knowledge and Public Policy FOIA’d these results more than a year ago and were refused by EPA. At its recent stakeholder meeting, OSHA staff said they aksed EPA for the results and were turned down as well.

I cannot explain why the EPA was adamantly opposed to sharing these results with the public or other regulatory agencies. The journal in which the article appeared, Critical Reviews in Food Science and Nutrition, does not prohibit scientists from discussing studies before publication. Perhaps one of our readers can help us understand the EPA’s actions, since it makes little sense to me.

3 thoughts on “EPA Microwave Popcorn Emissions Study Finally Published

  1. I have been following with interest the diacetyl saga for about a year and a half since reading a small newspaper article about the successful lawsuit by workers exposed to the product. I am a hazardous materials response and safety specialist. I train workers who will be working with and/or responding to hazardous materials/wastes. One of my primary goals is to train students to evaluate the hazards of chemicals they may come in contact with while on the job.
    A few months ago I began using David Michaels article “Popcorn Lung Coming to Your Kitchen? The FDA doesn’t want to know”, as a handout to generate discussion. Reactions to the information ranged from anger and disbelief to being resigned to the fact that government is in the pocket of big business. When asked for an opinion as to why the EPA test data was released to industry and not made public, the answer was that obviously the chemical was a threat to the consumers of microwave popcorn.
    Since then the popcorn industry has volunteered to remove diacetyl from their microwave popcorn. Congress has passed legislation to establish safe levels for workers who might be exposed to diacetyl.
    My concern is that it does not protect the public from exposure to this chemical at home or in the office lunchroom or break room. Orville Redenbacher continues to make Butter flavered Popcorn oil for popping its regular popcorn in a pan or other utensil. The amount of oil used in a pan may be many times that which is in a microwave package, thereby increasing the airborne concentrations to which the consumer will be exposed. There are also aerosol butter flavered products available such as Pam which I suppose also contain diacetyl.
    With all of the focus on microwave popcorn, I hope that someone is looking into the other potential sources of exposure by this product. I am glad to see help for the workers in industry, but the threat to public health is still out there.
    As a sidenote this material is also known as 2,3 Butanedione. In the New Jersey Hazardous Substance Fact Sheets it is also known to cause anemia.

  2. From March 2002 to May 2005, I popped popcorn in a commercial kettle at my concession stand. I breathed the heavy smoke from the kettle when emptying it and in general tried to keep the buttery flavor in the air to increase business. After 2 CT scans, numerous pulmonary function tests, and a full lung biopsy, I was diagnosed as having Interstitial Pulmonary Fibrosis. At that time I was not aware of the diacetyl connection to the butter flavorings I was using. As of 6 weeks following my biopsy, my lung function was less than 40% and I was put on prednasone and oxygen therapy, which I continued for 9 months. I am a non-smoker and until that time was able to ride a bicycle 20 miles several times a week and once rode 86 miles.

    My pulmonologist is not aware of my popcorn concession operation, but I will inform him. I would welcome any information concerning studies on concession workers, though I would assume it would be similar to those who work in factories. My lung function is now hovering close to 70% and I walk 5 miles daily. I am very determined to increase my lung funtion. Comments?

    I am researching this now because if the food changes and produce toxin it affects our bodies and can cause all kinds of cancer or other diseases.
    i am not using it anymore.

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