Composition of e‐cigarette aerosols: A review and risk assessment of selected compounds

Abstract The potential harms and benefits of e‐cigarettes, or electronic nicotine delivery systems (ENDS), have received significant attention from public health and regulatory communities. Such products may provide a reduced risk means of nicotine delivery for combustible cigarette smokers while being inappropriately appealing to nicotine naive youth. Numerous authors have examined the chemical complexity of aerosols from various open‐ and closed‐system ENDS. This body of literature is reviewed here, with the risks of ENDS aerosol exposure among users evaluated with a margin of exposure (MoE) approach for two non‐carcinogens (methylglyoxal, butyraldehyde) and a cancer risk analysis for the carcinogen N ‐nitrosonornicotine (NNN). We identified 96 relevant papers, including 17, 13, and 5 reporting data for methylglyoxal, butyraldehyde, and NNN, respectively. Using low‐end (minimum aerosol concentration, low ENDS use) and high‐end (maximum aerosol concentration, high ENDS use) assumptions, estimated doses for methylglyoxal (1.78 × 10 −3 –135 μg/kg‐bw/day) and butyraldehyde (1.9 × 10 −4 –66.54 μg/kg‐bw/day) corresponded to MoEs of 227–17,200,000 and 271–280,000,000, respectively, using identified points of departure (PoDs). Doses of 9.90 × 10 −6 –1.99 × 10 −4 μg/kg‐bw/day NNN corresponded to 1.4–28 surplus cancers per 100,000 ENDS users, relative to a NNN‐attributable surplus of 7440 per 100,000 cigarette smokers. It was concluded that methylglyoxal and butyraldehyde in ENDS aerosols, while not innocuous, did not present a significant risk of irritant effects among ENDS users. The carcinogenic risks of NNN in ENDS aerosols were reduced, but not eliminated, relative to concentrations reported in combustible cigarette smoke.