Ice flavours and non-menthol synthetic cooling agents in e-cigarette products: a review

Abstract

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.

Ice Flavor–Related Discussions on Twitter: Content Analysis

“…In the context of these regulations, ice hybrid–flavored products were introduced into the market [ 3 , 7 ]. Ice hybrid–flavored products combine a cooling flavor with fruit, dessert, or other characterizing flavor (eg, blueberry ice or melon ice), which may allow e-cigarette companies to circumvent regulatory action [ 10 , 11 ]. Recent evidence suggests that the use of ice-flavored e-cigarettes among young adults may be common and positively associated with combustible tobacco use [ 10 , 12 ].…”

“…Ice hybrid–flavored products may contain menthol. Menthol is a flavor additive that produces pleasant cooling sensations and analgesic effects in the throat and mouth, which reduces the harshness of combustible smoke and nicotine’s irritating effects on the airways [ 11 , 12 ]. Research from human and animal studies indicates that menthol increases the intensity of how cigarettes are smoked (eg, deeper inhalation) and facilitates smoking initiation and nicotine intake [ 11 , 13 , 14 ].…”

Expanding the E-Liquid Flavor Wheel: Classification of Emerging E-Liquid Flavors in Online Vape Shops

“…Finally, with a semantic database developed for flavors, our study could shed light for future research that identifies “concept flavors”—a group of ambiguous or vague descriptors that evoke sensory or other pleasant experiences (e.g., jazz, ice, etc.). Concept flavors could replace characterizing flavors as a marketing strategy and continue to attract consumers when products with explicit flavors are banned by authorities [ 43 , 57 , 58 ]. Our database will allow researchers to identify products that do not fall into any of the known flavor categories, thereby assisting in the evaluation of whether these producers adopt concept flavors to market these products.…”

E-cigarette Flavors, Sensory Perception, and Evoked Responses

“…2-isopropyl- N ,2,3-trimethylbutyramide (WS-23) and N -ethyl- p -menthane-3-carboxamide (WS-3) are examples of synthetic cooling agents commonly added to e-cigarette flavors often indicated as “chilled”, “ice”, “polar” or “cooled” in their names. , A significant increase in the marketing of the above indicated flavored e-cigarettes in the US also occurred in tandem with the FDAs 2020 enforcement policy of flavored e-liquids. − A recent study also reported that both WS-3 and WS-23 were major components detected in nicotine-containing e-liquids provided by a significant number of e-cigarette, or vaping, product use-associated lung injury patients from August 2019 to June 2021 . These data are particularly startling in that another study determined that WS-23 is present in e-liquids marketed in the US at levels that may potentially exceed the World Health Organization’s margin of exposure .…”