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Does Diacetyl in Vaping Cause Popcorn Lung?

Jim McDonald
December 21, 2018

What is popcorn lung?

Popcorn lung is a slang name for a serious condition with the scientific name bronchiolitis obliterans, or obliterative bronchiolitis. Sometimes the name is abbreviated as BO, and it is occasionally called constrictive bronchiolitis.

Popcorn lung is caused when the smallest airways within the lungs (bronchioles) are scarred, and their capacity and efficiency are reduced. There is no cure for the condition except a lung transplant.

Bronchiolitis obliterans can result from a variety of medical and environmental causes. The bronchioles can become inflamed and damaged from viral, bacterial and fungal infections, or by inhalation of chemical particles. Although diketones like diacetyl are the chemicals most often associated with popcorn lung, the National Institutes of Health lists several other chemicals that can cause it, including chlorine, ammonia, sulfur dioxide, and inhaled metal fumes from welding.

And despite being the only real cure for popcorn lung, lung transplants themselves can cause it too. In fact, bronchiolitis obliterans syndrome (BOS) is the single largest cause of chronic lung transplant rejection.

What are the symptoms of popcorn lung?

The scarring of the lung tissue blocks the airways and prevents the lungs from functioning properly. The symptoms are very similar to those of chronic obstructive pulmonary disease (COPD), but bronchiolitis symptoms can appear within just 2-8 weeks, while COPD typically takes many years or even decades to develop. Early bronchiolitis symptoms include:

  1. A dry cough
  2. Shortness of breath
  3. Reduced activity tolerance
  4. Wheezing (without a cold or asthma)
  5. Fatigue

Although popcorn lung is an incredibly rare disease, the early symptoms are similar to a common cold. Over a period of weeks or months, those symptoms progress and become more severe. Eventually the disease causes a variety of severe problems with breathing and absorption of oxygen. Untreated, popcorn lung causes death from respiratory failure within months or years.

There is no cure for popcorn lung, but treatment can sometimes slow its progression. Depending on the cause, popcorn lung is sometimes treated with antibiotics, immunosuppressive drugs, or corticosteroids. Cough medication or oxygen may be given to help manage symptoms. Severe cases may require a lung transplant.

Popcorn lung can be difficult to diagnose. Although CT scans and pulmonary function tests can offer strong clues, the only reliable way to identify the disease is through a surgical lung biopsy. And sometimes multiple biopsy samples are required to be certain.

Why is it called popcorn lung?

In 2002, the Centers for Disease Control and Prevention (CDC) documented eight cases of lung disease in employees who had worked at a Missouri popcorn factory between the years 1992 and 2000. Investigation showed that those with the worst lung damage had spent considerable time mixing a flavoring chemical called diacetyl with hot oil in large industrial-sized vats.

Although the popcorn workers who were diagnosed with obliterative bronchiolitis had severe and irreversible lung damage, the National Institute for Occupational Safety and Health (NIOSH, an agency within the CDC) found that the workers at the factory showed a spectrum of injury to the lungs probably caused by the flavoring chemicals. Not every affected employee had untreatable lung obstruction.

The diagnosis of bronchiolitis obliterans in the widely publicized cases earned the disease the nickname popcorn lung. In fact, bronchiolitis is so associated with the popcorn factory story that many people don’t know that popcorn lung can have causes other than diacetyl.

Popcorn lung vaping diacetyl

What is diacetyl?

Diacetyl is an organic compound that occurs naturally in fermented products like alcoholic drinks, and in cultured milk products. It’s also found in some fruits and in tobacco. Diacetyl is widely used as a flavoring in processed foods because of its buttery taste and ability to enhance sweet flavors. It was commonly used as an additive in “butter-flavored” microwave popcorn, consumed by millions the world over. After the popcorn lung investigations, most manufacturers stopped using butter flavoring with diacetyl.

Diacetyl is also known as 2,3-butanedione. It’s part of a chemical family called diketones. The other popular diketone used as a flavoring is acetyl propionyl, also known as AP or 2,3-pentanedione. A related flavoring chemical, acetoin, is a ketone (but not a diketone), and has similar properties.

Neither diacetyl nor AP poses any danger when ingested. The FDA designates both chemicals “generally recognized as safe” (GRAS), meaning there have been no observed negative health outcomes from eating or drinking them. However, inhaling diacetyl and similar flavorings — at least in large quantities, like the popcorn factory mixers did — can cause irreversible lung damage.

Popcorn lung, or bronchiolitis obliterans, is famously caused by industrial diacetyl fumes, and acetyl propionyl is likely just as dangerous. The CDC refers to obliterative bronchiolitis and related lung conditions as “flavorings-related lung disease,” and has published occupational exposure standards for diacetyl and other diketones.

Is there diacetyl in vapes?

There can be diacetyl in e-liquid. It’s not a given, but it’s a fact that it’s in some e-liquid on the market. Some e-liquids contain diacetyl or AP in the flavorings used to make them. The most obvious ones are e-juices with buttery flavors, like custards and other sweet desserts. But some candy- and fruit-flavored e-liquids and even tobacco flavors can also contain diketones like diacetyl.

Vapers have had concerns about diacetyl and health to vapers almost since vaping began, but the topic was first addressed scientifically in a 2014 paper by cardiologist Konstantinos Farsalinos and three colleagues. Their research found diacetyl and AP in a large number of sweet-flavored e-liquids, and deemed the diketones “an avoidable risk.” After the study, there was heated debate in the vaping community that resulted in many companies reformulating their products, but not all did. And not all vapers even wanted them to.

For vapers concerned about diacetyl, there are some companies that are recognized for their diketone-free formulations. And if you live in the U.K. or European Union, diacetyl is prohibited as an ingredient in nicotine-containing e-liquid.

Does vaping cause popcorn lung?

There has never been a single reported case of popcorn lung from vaping. Having said that, there are plenty of news stories that suggest vaping can cause it. There’s no evidence to support vaping as a cause of popcorn lung, in any vaping studies or otherwise, but maybe diacetyl in cigarette smoking could shed some insight about the possibilities. Cigarette smoke contains at least 100 times as much diacetyl as the highest levels in any vaping product, yet smoking is not associated with popcorn lung.

Despite the one billion smokers in the world who inhale diacetyl regularly in cigarettes, no smoker has been diagnosed with popcorn lung. And the few smokers known to have contracted popcorn lung were workers in a popcorn factory. According to NIOSH, smokers with bronchiolitis exhibit a discernibly more severe kind of lung damage than smokers with the usual (and still terrible) smoking-caused respiratory diseases like emphysema.

Despite the well-known risks of smoking, popcorn lung is not considered one its outcomes. Of course, lung cancer and chronic obstructive pulmonary disease (COPD) are associated with smoking from inhalation of carcinogenic compounds, tar, and carbon monoxide. But vapes don’t involve combustion, so they don’t produce any tar or carbon monoxide — and in the worst-case scenario, they only contain about one percent of the diacetyl that’s in cigarettes. While almost anything is possible, there’s simply no evidence that vaping causes popcorn lung.

Smokers created vaping without any help from the tobacco industry or anti-smoking crusaders, and vapers have the right to keep innovating to help themselves. My goal is to provide clear, honest information about the challenges vaping faces from lawmakers, regulators, and brokers of disinformation. I recently joined the CASAA board, but my opinions aren’t necessarily CASAA’s, and vice versa. You can find me on Twitter @whycherrywhy


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Daniel Hehir
Daniel Hehir

Great information thank you!


Thanks so much for the reassuring information. I had looked up this subject on Web MD and it mentions diacetyl but not how unlikely it is to get the condition. Your information is far more comprehensive and reassuring.
Maybe submit your article to them, so as to stop frightening people.
Many thanks,

Jack Stewart
Jack Stewart

Hi, so I have a question that’s been on my mind and I’m in a debate about popcorn lung and vaping with one of my friends. I’ve done research, and found that popcorn lung is not a reportable disease. So if one is diagnosed, they do not have to report it and let everyone in the world know, they could just keep it confidential and no one would ever know. How could you say that not one single vaper or smoker has never gotten diagnosed with popcorn lung, if it’s not a reportable disease? Thousands could be getting it but… Read more »

Liam Bailey
Liam Bailey

A teen just got popcorn lung from vaping. Can you explain how, why, and if it’s even true? Thanks.


As of today there have been 6 deaths related to vaping. I think your info needs to be updated. The reason deacetyl doesn’t harm smokers of cigarettes is because the oil component is not involved.

Stu Dowling
Stu Dowling

Oil is not involved with regular nicotine eliquid either. It’s not an oil, it’s a water soluble liquid. Propylene glycol is water soluble, vegetable glycerin is water soluble. The flavoring is water soluble, and the nicotine is in a base of either PG or VG, both of course which are water soluble. Vegetable glycerin may look and feel like oil, and even though it’s a byproduct of oil, usually coconut or palm kernel oil, it is actually a sugar alcohol or carbohydrate, which is not the same as oil. Oil is basically fat at room temperature. Have you ever tried… Read more »

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