The study, published in the journal Environmental Health Perspectives, analyzes a host of e-liquid flavors to discover levels of potentially dangerous chemicals diacetyl, acetyl propionyl, and acetoin.
The researchers found one or more of the three chemicals in 92 percent of the 51 unique flavors of e-liquid. Diacetyl is identified in 39 of 51 flavors – 75 percent of the total.
Following the study, an array of media outlets focused on the presence of diacetyl, a chemical used for food flavoring that if inhaled in large amounts can lead to a severe respiratory disease – bronchiolitis obliterans.
Bronchiolitis obliterans is commonly known as “popcorn lung,” because it was identified in workers who inhaled the artificial butter flavor used to make microwavable popcorn. A number of cases of popcorn lung have been found to be so severe in some patients that they have required a full-blown lung transplant.
The Harvard study whipped up a storm of hyperbolic headlines including “Harvard study finds that E-cigarette flavors cause lung disease” and “Chemicals in Flavored E-Cigarettes Tied To ‘Popcorn Lung’ Disease.”
But the headlines may be shielding the truth about the potential risk of popcorn lung from using e-cigarettes. Dr. Konstantinos Farsalinos, an expert on e-cigarette research and an opponent of putting diacetyl in e-liquids, writes, “tobacco cigarette smoke contains high levels of diacetyl and acetyl propionyl, on average 100 and 10 times higher,” compared to average e-cigarette exposure.
Farsalinos draws the disparity between tobacco and e-cigarettes from research conducted by himself and colleagues published in the journal Nicotine and Tobacco Research in 2014.