Effects of non-tobacco flavors and nicotine on e-cigarette product appeal among young adult never, former, and current smokers

Background: E-cigarette regulations targeting products that disproportionately appeal to never-smokers may optimize population health. This laboratory study of young adults tested whether differences in appeal between e-cigarettes with non-tobacco-flavored (vs. tobacco-flavored) and nicotine-containing (vs. nicotine-free) solutions varied by smoking history. Methods: Current (N = 53), former (N = 25), and never (N = 22) cigarette smokers who vape (Mean [SD] age = 25.4[4.4] years) administered standardized e-cigarette doses varied by a Flavor (fruit, menthol, tobacco) x Nicotine (nicotine-containing [6 mg/mL], nicotine-free) within-subject double-blind design. Participants rated each dose's appeal (0-100 scale). Covariate-adjusted interactions tested whether smoking history moderated flavor and nicotine effects. Results: Appeal was higher for fruit and menthol than tobacco flavors in each group. The fruit vs. tobacco appeal difference was greater in never smokers (fruit tobacco estimate = 19.6) than current smokers (estimate = 12.1) but not former smokers (estimate = 12.6). The menthol vs. tobacco difference was greater in never smokers (menthol tobacco estimate = 17.3) than former (estimate = 6.0) and current (estimate = 7.2) smokers. Appeal was lower for nicotine-containing than nicotine-free solutions in each group; this difference was greater in never smokers (nicotine nicotine-free estimate = -17.3) than former (estimate = -7.0) and current (estimate = -10.6) smokers. Compared to tobacco flavors, nicotine's appeal-reducing effects were suppressed by fruit and menthol flavors in never smokers. Conclusions: Higher appeal of non-tobacco-flavored (vs. tobacco-flavored) and lower appeal of nicotine-containing (vs. nicotine-free) e-cigarettes may be widespread in young adults but disproportionately amplified in never smokers. Non-tobacco flavors may suppress nicotine's appeal-lowering qualities in never smokers. The impact of regulating non-tobacco flavors in e-cigarettes may vary by smoking history.