In the early 2000s, several workers of a popcorn plant became ill with bronchiolitis obliterans – or “popcorn lung” – after they endured long-term exposure to diacetyl, a chemical used in flavorings to mimic the creamy taste of butter. Although many major popcorn manufacturers have since taken the chemical out of their microwave popcorn, people are still at risk for exposure.
Diacetyl can be found in baking mixes, candy, alcohol, flavored yogurt, snack foods, cheese, and coffee. According to the FDA, diacetyl is safe when consumed in trace amounts. But when it is inhaled, the person is at risk for developing serious lung diseases such as bronchiolitis obliterans, which is only treatable by lung transplant.
However, a recent study revealed that diacetyl poses a major risk to consumers though e-cigarettes. The study tested e-cigarettes for diacetyl as well as acetoin and 2,3-pentanedione, two chemicals that are used similarly and seem to have the similar negative effects on health. Ninety-two percent of the e-cigarettes tested contained one or more of these chemicals.
The study’s lead author, Joseph G. Allen, assistant professor of exposure assessment science at the Harvard T.H. Chan School of Public Health, said, “The flavoring is in a liquid form and our concern is that the exposure pathway is similar to that of the workers who are getting sick.” Allen further explained that inhaling heated flavoring chemicals is similar to the exposure that the microwave plant workers experienced.
“There are no defined safe limits to these chemicals at all for exposure through these e-cigarettes,” said Allen. For frequent and heavy vapers, “frequency and duration of exposure could be higher than those of workers.”