E-cigarettes with cooling flavours have diversified in ways that complicate tobacco control with the emergence of: (1) Ice-hybrid flavours (eg, ‘Raspberry Ice’) that combine cooling and fruity/sweet properties; and (2) Products containing non-menthol synthetic cooling agents (eg, Wilkinson Sword (WS), WS-3, WS-23 (termed ‘koolada’)). This paper reviews the background, chemistry, toxicology, marketing, user perceptions, use prevalence and policy implications of e-cigarette products with ice-hybrid flavours or non-menthol coolants. Scientific literature search supplemented with industry-generated and user-generated information found: (a) The tobacco industry has developed products containing synthetic coolants since 1974, (b) WS-3 and WS-23 are detected in mass-manufactured e-cigarettes (eg, PuffBar); (c) While safe for limited oral ingestion, inhalational toxicology and health effects from daily synthetic coolant exposure are unknown and merit scientific inquiry and attention from regulatory agencies; (d) Ice-hybrid flavours are marketed with themes incorporating fruitiness and/or coolness (eg, snow-covered raspberries); (e) WS-23/WS-3 concentrates also are sold as do-it-yourself additives, (f) Pharmacology research and user-generated and industry-generated information provide a premise to hypothesise that e-cigarette products with ice flavours or non-menthol cooling agents generate pleasant cooling sensations that mask nicotine’s harshness while lacking certain aversive features of menthol-only products, (g) Adolescent and young adult use of e-cigarettes with ice-hybrid or other cooling flavours may be common and cross-sectionally associated with more frequent vaping and nicotine dependence in convenience samples. Evidence gaps in the epidemiology, toxicology, health effects and smoking cessation-promoting potential of using these products exist. E-cigarettes with ice flavours or synthetic coolants merit scientific and regulatory attention.

Rationale Electronic cigarette (e-cigarette) aerosol contains volatile aldehydes, including flavourings and oxidant metals with known pulmonary toxicity. Objectives To evaluate the associations of e-cigarette use with symptoms of wheeze, bronchitic symptoms and shortness of breath (SOB) across 4 years of prospective data. Methods Participants completed questionnaires on respiratory symptoms and past 30-day e-cigarette, cigarette and cannabis use in 2014 (wave 1; N=2094; mean age 17.3 years, SD=0.6 years). Follow-up information was collected in 2015 (wave 2; n=1609), 2017 (wave 3; n=1502) and 2018 (wave 4; n=1637) using online surveys. Mixed-effects logistic regression models evaluated associations of e-cigarette use with respiratory symptoms. Measurements and main results Participants were mostly Hispanic white (51.8%) and evenly representative by sex (49.6% female; 50.4% male). Compared with never e-cigarette users, past 30-day e-cigarette users reported increased odds of wheeze (OR 1.81; 95% CI 1.28, 2.56), bronchitic symptoms (OR 2.06; 95% CI 1.58, 2.69) and SOB (OR 1.78; 95% CI 1.23, 2.57), adjusting for study wave, age, sex, race, lifetime asthma diagnosis and parental education. Effect estimates were attenuated (wheeze (OR 1.41; 95% CI 0.99, 2.01), bronchitic symptoms (OR 1.55; 95% CI 1.18, 2.05), SOB (OR 1.48; 95% CI 1.01, 2.18)), after adjusting additionally for current cigarette use, cannabis use and secondhand exposure to e-cigarettes/cigarettes/cannabis. Conclusions E-cigarette use in young adults was associated with respiratory symptoms, independent of combustible cannabis and cigarette exposures.

Public health efforts have been effective in reducing the use of cigarettes among youths, and rates of cigarette use are the lowest ever recorded¹; however, use of e-cigarettes (ECs) by youths has substantially increased in recent years.^1-4 The findings from the 2018 National Youth Tobacco Survey showed a 75% increase in EC use among high school students between 2017 and 2018.^1,5 This increased prevalence of EC use may be associated with the development of nicotine dependence and a future transition to other harmful tobacco products among adolescents.⁶ In addition, there may be respiratory effects of ECs; one concern is that the use of ECs may be associated with risk of respiratory symptoms such as wheezing among youths.^7,8

Oral nicotine pouches may appeal to young adult current nicotine/tobacco users interested in alternative forms of nicotine that lack pulmonary exposure, but may also appeal to young adult non-users of nicotine/tobacco products. We used data from a 2020 remote digital survey of an ongoing cohort study of young adults from Southern California (aged 19–23) to examine differences in pouch perceptions and use willingness across nicotine/tobacco use statuses. Participants who had never used nicotine pouches (N = 1167) viewed text/imagery from mass-marketed pouch packaging and advertising, then completed measures of willingness to use nicotine pouches, pouch harm perceptions, and hypothetical choice of cigarettes or e-cigarettes over pouches. Willingness to use pouches was significantly higher among non-combustible only (33.8%), combustible only (29.3%), and dual (43.9%) users than non-users (14.7%). Overall, 49.1% of participants were uncertain whether pouches were less harmful than cigarettes and 52.4% were uncertain whether pouches were less harmful than e-cigarettes. Relative harm perceptions did not significantly differ by tobacco use status. Those using non-combustible products (either alone or as part of dual use with combustible tobacco) had greater odds than non-users of reporting that they would use e-cigarettes over nicotine pouches. By contrast, all tobacco product user groups reported greater odds than non-users that they would use cigarettes over pouches. In sum, a sizable minority of young adults might be willing to try using nicotine pouches, but most are uncertain about the relative harm of pouches.