Researchers at Harvard’s school of public health have published a new study about the safety of electronic cigarettes, and it has nothing to do with nicotine. More than 75% of the flavored e-cigarettes the researchers tested contained the chemical diacetyl, which multiple studies have linked to lung damage.
Diacetyl is a flavoring agent that was initially investigated by the US Centers for Disease Control (CDC) as a culprit of “popcorn lung,” a type of bronchitis affecting workers at microwave popcorn factories and coffee roasting facilities. Although diacetyl is safe to eat, inhaling it “in the forms and amounts to which food and chemical industry workers may be exposed” may cause lung disease, the CDC said. The ailments include bronchiolitis obliterans, in which the lungs’ small airways are damaged by scar tissue and inflammation.
Diacetyl is one of several chemicals responsible for imbuing flavors such as “Madagascar Bourbon vanilla,” “cherry crush,” and “candy cane” in some of the 7,000 varieties of e-cigarettes and refillable cartridges on the market.
The Harvard researchers, who published their study in Environmental Health Perspectives, tested “51 types of flavored e-cigarettes sold by leading e-cigarette brands and flavors we deemed were appealing to youth” in a sealed chamber. In addition to diacetyl, the air streams were analyzed for acetoin and 2,3-pentanedione, two other flavoring compounds identified by the CDC as potentially harmful. Diacetyl was found in 39 of the 51 samples, acetoin was found in 46, and 2-3 pentanedione was found in 23.
As another group of researchers concluded earlier this year, after publishing a similar study in the journal Tobacco Control, these flavoring chemicals may be technically “food-grade” but that doesn’t mean they’re safe to inhale.