Chemical reactions involving e-cigarette flavorings may produce new chemicals that
irritate a user’s lungs, according to a new study.
E-cigarettes come in thousands of flavors, including cherry, cinnamon, citrus and
vanilla, which are produced using flavor aldehydes benzaldehyde, cinnamaldehyde, citral,
ethylvanillin and vanillin.
To explore potential chemical reactions, researchers mixed these aldehydes with e-liquid
solvents propylene glycol (PG) and glycerol. About 40% converted to flavor aldehyde
PG acetals. Roughly 50% to 80% of the acetals then were detected in e-cigarette vapor.
The team found these acetals activated TRPA1 and TRPV1 irritant receptors, potentially
causing lung irritation. Children and teens may be more susceptible than adults, and
long-term effects are unknown, according to the authors.
“These individual ingredients are combining to form more complex chemicals that are
not disclosed to the user,” senior author Sven-Eric Jordt, Ph.D., said in a news release.
“When inhaled, these compounds will persist in the body for some time, activating
irritant pathways. Over time, this mild irritation could cause an inflammatory response.”
Researchers also discovered some cigarette labels listing chemical content were inaccurate.
They stressed the importance of accurate labels and including warnings about possible
impact of the e-cigarette solvents being mixed with flavoring chemicals.
“To fully assess the risk potential of e-liquid use for regulatory purposes, it is
imperative that the compounds that a user will actually be exposed to are reported
and evaluated, and not only the initial ingredients combined during manufacturing,”
authors wrote in the study.
Flavors have been blamed for recent spikes in teen use of e-cigarettes. About 3 million
high school students use e-cigarettes, according to federal health officials. The
Food and Drug Administration recently announced a plan to limit where e-cigarettes
can be sold to keep them out of the hands of teens. The Academy has said the plan
does not go far enough and has advocated for banning flavors.