Myth: Vaping causes Popcorn Lung

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What is Popcorn Lung?

The technical term for this illness is Bronchiolitis obliterans. It can be referred to as obliterative bronchiolitis or bronchiolitis obliterans syndrome. It has also been called “Silo-fillers Lung” due to people becoming ill after breathing the gasses from sillage.

Bronchiolitis obliterans is a rare lung condition that affects the small airways, blocking air movement by causing constriction and scarring.

Most patients with Bronchiolitis obliterans are treated with medications and therapy by a multidisciplinary team. Those patients will experience a poor quality of life, and the majority of them will die prematurely from respiratory failure.

What causes Popcorn Lung / Bronchiolitis Obliterans?

Bronchiolitis obliterans is rare. It was first mentioned in 1835, and it was not until 1901 that it was mentioned again in medical writings. At that time, inhalation of toxic fumes or foreign bodies and respiratory infections were attributed to causing Bronchiolitis obliterans.

Bronchiolitis obliterans syndrome afflicts about 50% of lung transplant patients within five years and 2% - 6% of hematopoietic stem cell transplantation patients. Some patients with autoimmune diseases are prone to it, too.

Bronchiolitis obliterans can occur after chemical agent exposure, which has been an occupational hazard in agriculture and manufacturing. It has affected workers who make microwave popcorn, coffee, flavorings, etc. It has been found in employees of textile and other industries. Veterans exposed to gasses and burn pits, along with people exposed to the dust and fumes from the collapse of the World Trade Center, have also experienced bronchiolitis obliterans. Some viral infections can cause bronchiolitis obliterans.

If it has a scientific name, why is it called Popcorn Lung?

From the Centers for Disease Control and Prevention: "In 2000, a physician reported that eight former microwave-popcorn factory workers had developed a rare and disabling lung disease, bronchiolitis obliterans. Four of the eight workers were ill and put on lung transplant waiting lists. After investigating numerous possible sources, researchers ultimately determined the cause of lung damage: a vapor from butter flavoring added to the popcorn."

Diacetyl is the chemical that gave the microwave popcorn its buttery flavor.

Is Popcorn Lung the same thing as EVALI?

The two diseases are often conflated but are not the same.

While a variety of things can cause bronchiolitis obliterans (Popcorn Lung), it has been determined that E-cigarette, or Vaping, product use-Associated Lung Injury (EVALI) can be attributed to the addition of Vitamin E to make unregulated vape cartridges containing tetrahydrocannabinol (THC) from marijuana look thick and of higher quality. The additive was used for a brief period of time in 2019-2020. These thickeners were pulled from the market by their manufacturers as news of the EVALI outbreak spread.

Nicotine vapor products did not cause EVALI. Leading experts requested the Centers for Disease Control and Prevention (CDC) change the name of EVALI to help consumers better understand the difference between vaping THC and nicotine. The CDC declined to make that change.

Why are some experts claiming vaping causes Popcorn Lung?

In 2015 the paper "Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-Cigarettes" was published. The authors found Diacetyl in some of the e-liquids they tested. They concluded, "Our findings confirm the presence of diacetyl and other flavoring chemicals in flavored e-cigarettes. Because of the associations between diacetyl and bronchiolitis obliterans and other severe respiratory diseases among workers inhaling heated vapors containing diacetyl, urgent action is recommended to further evaluate the extent of this new exposure to diacetyl and related flavoring compounds in e-cigarettes." (The vapors that workers inhaled were not vapor from an e-cigarette.) Twitter thread about study

Harvard T.H. Chan School of Public Health issued a press release about the study, "Chemicals linked with severe respiratory disease found in common e-cigarette flavors" (Link saved on Wayback Machine). While the safety of e-cigarettes does need to be monitored, the study and the press release did not compare the levels of the chemicals found to what is inhaled from smoking a combustible cigarette. Neither the paper nor the press release said people will get Popcorn Lung from vaping. They just raised concern about the possibility.

While Dr. Farsalinos is strongly opposed to the use of Diacetyl in e-liquids, he is concerned about the study because "the article is creating false impressions and exaggerates the potential risk from diacetyl and acetyl propionyl exposure through e-cigarettes. They failed to mention that these chemicals are present in tobacco cigarette smoke and violated a classical toxicological principle that the amount determines the toxicity and the risk."

Dr. Brad Rodu has concerns about the methods used in this study and said in his blog, "As I advised previously, vapers should only use liquids that are certified to be free of buttery flavors that are suspected respiratory toxicants. However, laboratory investigations of e-cigarettes should use validated methods to assure credibility. The results of the Harvard Buttery Flavor Study do not meet this standard."

Science writer Carrie Arnold commented on this study and said, "This study did not assess levels of diacetyl, 2,3-pentanedione, and acetoin in actual users, much less health effects. So it’s premature to assume that exposure to these chemicals via e-cigarettes causes health problems."

The study and alarm over the potential danger of vaping made headlines across the US and globally. Most of the articles failed to mention there are more of these chemicals in combustible cigarettes, and there are no documented cases of Popcorn Lung being caused by smoking or vaping.

A chemical of concern that might pose potential harm swiftly morphed into known harm, and word began to spread that vaping causes Popcorn Lung, even though there were no documented cases of it actually occurring. A 2015 report published in the Milwaukee Journal Sentinal gave a historical run-down of cases of Popcorn Lung in the food industry and questioned why Diacetyl was allowed in e-cigarettes.

The American Lung Association added information about Popcorn Lung and vaping on their website in 2016.

In 2018, Jonathan Winickoff, the former chair of the American Academy of Pediatrics Tobacco Consortium, a pediatrician at Massachusetts General Hospital and a professor at Harvard Medical School, said that he "believes that the vape industry is co-opting the national wellness trend—when, in fact, vaping can cause something called bronchiolitis obliterans, or popcorn lung."

Schools, in an attempt to keep teens safe and discourage them from experimenting with vaping began telling students they could get Popcorn Lung from vaping.

Misperceptions about the risk of getting Popcorn Lung from vaping can lead some people who smoke to avoid trying this safer alternative to help them quit smoking. A point that was made by Jennifer Pierce, Anders Abelmann, and Brent Finley in their commentary about the 2015 flavoring study.

What actions were taken to protect consumers after the study was released?

  • Many e-liquid manufacturers switched to Diacetyl-free ingredients.
  • Most flavor manufacturers reformulated their flavoring to Diacetyl-free formulas.
  • As a further precaution to avoid the potential for there to be an issue in the future, some countries have banned the use of Daicetyl in e-liquids. Examples include Australia,Northern Ireland, Great Britain, and member states of the EU Tobacco Products Directive (TPD).
  • A study published in 2021 found "that the mean number of chemicals detected per product has in fact changed over the years; products collected in 2017 and 2018 appear to have a significantly higher number of chemical compounds when compared to those collected in 2019. This trend is observed regardless of flavour category analyzed. Of the 825 samples tested "diacetyl was detected in two vaping liquids acquired prior to 2018, 2,3 pentanedione was not detected in any vaping liquids analyzed in the Open Characterization dataset." No Diacetyl was found in the liquids acquired after 2018.

Where can I get reliable information on vaping and Popcorn Lung?

Are there any articles, videos, or Op-Eds pointing out the misinformation surrounding this myth?

Who has corrected or deleted their incorrect information on Popcorn Lung?

Who's information can lead people to believe that vaping causes Popcorn Lung?

Some of these websites don't specifically say that people who vape get Popcorn Lung. They mention diacetyl is in e-cigarettes and that diacetyl can cause popcorn lung. Their failure lies in neglecting to point out that popcorn lung is rare, there is more diacetyl in combustible cigarettes than vapor products, and there are no documented cases of popcorn lung that can be directly attributed to vaping.

(To Do List - SAVE all links on Wayback)


We are not health care practitioners. The information here is not meant to be medical advice. Due to overwhelming amounts of misinformation about nicotine, it is difficult to get accurate medical advice. The best thing you can do is not vape or smoke. Clean (unpolluted) air is the best thing for your lungs. If you wish to inhale nicotine, current evidence shows that while not "safe," vaping is safer than smoking and can help some people stop smoking.

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