Objections to an article published by Harvard Health saw a tweet taken down and a review conducted. But the article, which misleadingly links nicotine vapes to “popcorn lung” and “EVALI,” remains online.
The article—titled “Popcorn lung: What is it, and who is at risk?”—was originally published on December 21 by Harvard Health, the consumer health information division of Harvard University’s medical school. The Harvard Health X account, which has 2.5 million followers, soon tweeted it out, quoting a line from the piece: “Experts say it’s possible that using e-cigarettes and vaping can cause popcorn lung.”
Tobacco harm reduction advocates reacted, and the tweet received a community note on the platform based on readers’ concerns over misinformation. The tweet—as Gregory Conley, director of legislative and external affairs for American Vapor Manufacturers, noted on December 26—was then deleted.
The article, however, was not, though a note since added suggests that it was reviewed by a senior faculty editor on January 2.
Neal L. Benowitz, emeritus professor of medicine at the University of California, San Francisco, said risks of vaping are “exaggerated” in the article.
Some changes from the original version were apparent, including the removal of the stronger statement: “Many experts agree that there is a link between popcorn lung and vaping. They point out that diacetyl is a proven cause of popcorn lung, and that diacetyl is a flavoring used in some cigarettes.”
Neither Harvard Health nor the author of the article responded to Filter’s requests for comment.
Neal L. Benowitz, emeritus professor of medicine at the University of California, San Francisco, told Filter that risks of vaping are “exaggerated” in the Harvard Health article.
Many reputable sources have described the idea that vaping causes the rare condition bronchiolitis obliterans, known as “popcorn lung,” as a myth—or at least, as a contention unsupported by evidence.
There’s some evidence linking the disease to exposure among factory workers to diacetyl—a chemical used as a food flavoring and present in alcoholic drinks, as well as in some vapes. But the presence of a chemical does not demonstrate that it is present in sufficient quantities to cause harm.
The changes to the Harvard Health article included describing diacetyl as found in “some flavored e-cigarettes,” when it previously read “many.”
“At one time diacetyl was commonly found in e-liquids,” Dr. Benowitz said. “This is not the case now, particularly with the e-cigarettes that are produced by large corporations.” (In the United Kingdom, diacetyl has been banned as an ingredient in e-liquids.)
“Furthermore, there is a higher level of diacetyl in cigarette smoke compared to that found in some of the older e-liquid emissions,” Benowitz added. Smoking, he said, “causes many severe lung diseases, but ‘popcorn lung’ is not one of them.”
On this question, Action on Smoking and Health, a leading British charity, has made a similar point: “The idea that vaping can cause popcorn lung is frequently repeated, but although cigarette smokers are exposed to over ten times as much diacetyl as people who vape, smoking has not been shown to cause ‘popcorn lung.’”
“The persistence of the idea … has prompted several health bodies, including Health Canada, the New Zealand Ministry of Health, and the UK Health Security Agency, to clarify that no evidence exists for such a link,” noted Michelle Minton in a 2023 debunking article for the Reason Foundation.
The Harvard Health article states: “The American Lung Association has called popcorn lung a dangerous risk of flavored e-cigarettes.”
The American Lung Association, which receives Bloomberg funding, is known for its anti-vaping stance and has been accused of spreading misinformation on the subject; the organization did not respond to Filter’s request for comment.
The article does acknowledge the role of vitamin E acetate in “EVALI,” but fails to make the nicotine/THC distinction clear.
“In addition,” the Harvard Health article continues, with language added in the revision, “thousands of cases of e-cigarette- or vaping-use-associated lung injury (EVALI) were reported in 2019 and 2020. This potentially fatal condition includes bronchiolitis, the inflammatory lung disease that occurs in popcorn lung.”
A problem here, in the context of an article about “popcorn lung” and e-cigarettes, is the implicit conflation of nicotine vaping with other forms of vaping.
“The EVALI epidemic was due to heating vitamin E acetate, which generated a potent lung toxin,” Benowitz said. “Some case reports of lung injury from nicotine vaping have appeared, but in many cases causation … has not been proven.”
Instead, as the CDC belatedly acknowledged, the overwhelming majority of lung injuries were among people who had used (unregulated) THC vaping products. “Researchers have linked vitamin E acetate, a synthetic form of vitamin E found in some THC-containing vaping products, to EVALI,” notes Yale Medicine.
The Harvard Health article does acknowledge the role of vitamin E acetate, but fails to make the nicotine/THC distinction clear—perpetuating the confusion that’s led tobacco control experts to urge that “EVALI” be renamed.
“When Harvard Health spreads misinformation about a rare condition that’s never before been seen in people who vape, it becomes a dangerous message that can reach millions.”
Widespread misconceptions about vaping have very real consequences. They damage public health by deterring people from switching from cigarettes to vastly safer nicotine vapes—a critical comparison that’s absent from the Harvard Health article.
“It seems that people are being inundated with misinformation about vaping as much today as ever before,” tobacco harm reduction advocate Phillip Kirschberg told Filter.
“When a small news outlet comes out with a piece about ‘popcorn lung,’ sadly, it doesn’t come as much of a surprise,” he continued. “But when Harvard Health spreads misinformation about a rare condition that’s never before been seen in people who vape, it becomes a dangerous message that can reach millions of people that deserve accurate information about this lifesaving alternative to smoking.”
This isn’t the first time Harvard Health has misled readers on vaping, Gregory Conley told Filter. The latest episode, he said, exposed “both the intransigence of public health activists and the overbearing arrogance of academics at elite institutions.”
“Despite numerous reviews highlighting the lack of evidence connecting ‘popcorn lung’ to nicotine vaping, individuals like the author and reviewer persist in their crusade,” he continued. “They appear to be more invested in fueling a perceived righteous war than upholding the truth.”