Elsevier

Drug and Alcohol Dependence

Volume 203, 1 October 2019, Pages 99-106
Drug and Alcohol Dependence

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

https://doi.org/10.1016/j.drugalcdep.2019.05.020Get rights and content

Highlights

  • The effect of e-cigarette flavor and nicotine on appeal in young adults was tested.

  • Sweet, menthol was more appealing than tobacco flavors in non-smokers, smokers.

  • Nicotine had acute unappealing qualities in both non-smokers and smokers.

  • Never smokers had largest preferences for non-tobacco flavors, away from nicotine.

  • Sweet, menthol flavors suppressed nicotine’s unappealing qualities in non-smokers.

Abstract

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) × 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.

Introduction

Product standards prohibiting the manufacture, marketing, and sales of electronic cigarettes (e-cigarettes) with specific product characteristics can substantially affect prevalence of vaping in the population and in turn markedly impact public health (Food and Drug Administration, 2018). E-cigarettes currently on the market are available in numerous non-tobacco flavors, such as menthol and a variety of fruit flavors (e.g., candy, fruit), and are sold in various nicotine concentration levels, including nicotine-free solutions (Camenga et al., 2018; Zare et al., 2018). Non-tobacco flavors and nicotine concentration have been targeted in existing or proposed product standards by the U.S. Food and Drug Administration (2018), European Union Tobacco Product Directive (Berteletti et al., 2017; European Commision Public Health, 2018), and other regulatory agencies (Canada House of Commons’ Standing Committee on Health, 2015; Tulsieram et al., 2017).

Differences in user-reported product appeal in response to systematic administration of tobacco products that vary in flavor or nicotine content in the laboratory under double-blind conditions can guide product standards (Carter et al., 2009; Carter and Griffiths, 2009). Such experiments can isolate causal effects of flavorings, nicotine, and other product constituents on appeal while experimentally controlling exogenous influences common to observational research (e.g., marketing, pre-existing beliefs about products, social influences). Evidence from previous laboratory experiments demonstrate that product appeal is higher for e-cigarettes with fruit-flavored or dessert-flavored (Audrain-McGovern et al., 2016; Bono et al., 2018; Goldenson et al., 2016; Kim et al., 2016; DeVito et al., 2019) or menthol-flavored (Krishnan-Sarin et al., 2017; Rosbrook and Green, 2016) solutions than tobacco-flavored or flavorless solutions. Nicotine concentration in e-cigarettes produce counterpoising effects. In addition to increasing neuropharmacological-mediated reinforcement due to nicotine absorption, products with higher nicotine concentration produce aversive acute sensory effects (i.e., perceptions of harshness or bitterness) that may reduce immediate subjective appeal (Etter, 2016; Goldenson et al., 2016; Hajek et al., 2018; Rosbrook and Green, 2016; DeVito et al., 2019). Nicotine concentration may interact with menthol flavorings such that menthol-related cooling sensations suppress nicotine’s unappealing sensory qualities (Krishnan-Sarin et al., 2017; Rosbrook and Green, 2016).

While observational research suggests that use and appeal of non-tobacco flavored e-cigarettes is greater in never smokers than smokers (Berg, 2015; Bonhomme et al., 2016; Farsalinos et al., 2013; Harrell et al., 2016; Patel et al., 2016; Rodu and Plurphanswat, 2018; Russell et al., 2018), prior controlled laboratory product appeal experiments have aggregated results across never, former, and current combustible cigarette smokers, leaving unclear whether product preferences in experimental research vary by smoking history. Translating this literature into actionable evidence to base regulations that benefit the entire population is difficult because smokers and non-smokers garner divergent health effects from exposure to e-cigarette products they find appealing.

Restricting the sale of products that appeal to never smokers could prevent nicotine addiction and reduce exposure to toxins in e-cigarette aerosols in a population who garners no health benefits from vaping (National Academies of Sciences et al., 2018; U.S. Department of Health and Human Services, 2016). Prohibiting the sale of products that appeal to smokers could discourage transition to e-cigarettes and perhaps encourage former smokers who vape to resume smoking. Optimal regulatory restrictions would target particular products with greater appeal in never smokers than former or current smokers. By doing so, regulations could reduce the appeal of e-cigarettes among never smokers without discouraging smokers from transitioning to e-cigarette use. Consequently, it is critical to identify e-cigarette product characteristics that disproportionately appeal to never smokers relative to current or former smokers to inform regulatory policies that optimize health impact to the population as a whole.

Although most middle-aged and older adults who vape are current or former smokers, never-smoking is common among young adult vapers (Centers for Disease Control and Prevention and National Center on Health Statistics, 2016). This laboratory study of young adult e-cigarette users tested whether smoking history moderated the individual and interactive effects of fruit and menthol (vs. tobacco) flavors and nicotine-containing (vs. nicotine-free) e-cigarette solutions on product appeal ratings. Given past observational research results (Berg, 2015; Bonhomme et al., 2016; Farsalinos et al., 2013; Patel et al., 2016), we hypothesized that the relative preference of fruit or menthol (vs. tobacco) flavors would be heightened in never smokers relative to former and current smokers. No a priori hypotheses were made regarding whether nicotine concentration’s main effects or interactive effects with flavor differed by smoking history.

Section snippets

Participants

Participants (N = 101) in Los Angeles, CA, USA responded to advertisements about a study on reasons for e-cigarette use in 2015. Inclusion criteria were: 1) 18–35 years old; 2) current e-cigarette use >1 day/week for >1 month; 3) use nicotine-containing (>0 mg/mL) e-cigarettes; and 4) English fluency. Exclusion criteria were: 1) plan to immediately reduce or quit vaping; 2) current smoking cessation medication use; or 3) pregnancy or breastfeeding. One participant who did not complete the

Sample characteristics

Descriptive statistics of demographics and tobacco product use characteristics, by smoking history, are reported in Table 1. The pooled sample had a mean age of 25.4 (SD = 4.4) years, was 35% female, was racially/ethnically diverse, and reported, on average, moderate e-cigarette dependence levels on the Electronic Cigarette Dependence Index. Never smokers were younger on average than former and current smokers. E-cigarette dependence was lower in never smokers than former and current smokers.

Discussion

This study provides new experimental evidence indicating that while most young adult e-cigarette users preferred fruit and menthol over tobacco flavors and found nicotine-containing solutions less appealing than nicotine-free solutions, these effects were amplified in never smokers relative to current and former smokers. We also found that menthol and fruit flavors suppressed nicotine’s appeal-reducing qualities among never smokers. In doing so, this study provides some of the most rigorous

Conclusions

All young adult vapers in this study, regardless of smoking history, found non-tobacco flavors more appealing than tobacco flavored e-cigarettes. Thus, an unfortunate reality is that regulatory policies that reduce the availability of non-tobacco flavors may not benefit the health of every segment of the population, namely smokers who aim to quit smoking with the aid of e-cigarettes and find non-tobacco flavors an appealing alternative to combustible cigarettes (Chen, 2018; Farsalinos et al.,

Role of funding source

The funding agencies had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Contributors

AML was the principal investigator responsible for study conception and directing data collection. AML and NG led the conceptualization of the manuscript and wrote the majority of the manuscript text. NG conducted the analyses and wrote initial drafts of the Results and Analytic Plan and prepared the tables and figures. MK, JBT, and RP aided in study conceptualization and provided feedback on drafts. All authors contributed to and approved of the final manuscript.

Declaration of Competing Interest

Dr. Goldenson left USC on February 10, 2019 and started as an employee of JUUL Labs as of March 4, 2019. He met criteria for authorship prior to leaving USC, and he had no role in revising the paper after leaving USC and joining JUUL Labs. There are no other interests declared by authors.

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