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Significance: IQOS is a heated tobacco product that has been widely advertised by Philip Morris International (PMI) as a reduced-exposure product compared with cigarettes. Reduced exposure results from reduced emission of toxicants which could be influenced by product constituents and user behaviour. This study aims to assess the influence of user behaviour, including device cleaning and puffing parameters, on toxicant emissions from IQOS., Methods: IQOS aerosols were generated by a smoking machine using the combination of two cleaning protocols (after 1 stick vs 20 sticks) and five puffing regimes (including standard cigarette puffing regimes and IQOS-tailored regimes). The generated aerosols were analysed by targeted methods for phenol and carbonyl quantification, and by chemical screening for the identification of unknown compounds., Results: Puffing parameters significantly affected phenol and carbonyl emissions while device cleaning had no effect. Harsher puffing conditions like more, longer, and larger puffs yielded higher levels for most toxicant emissions. Comparing the obtained data with data reported by PMI on 50 cigarette brands smoked under different puffing regimes showed various trends for phenol and carbonyl emissions, with IQOS emissions sometimes higher than cigarettes. Also, the chemical screening resulted in the tentative identification of ~100 compounds in the IQOS aerosols (most of limited toxicity data)., Conclusion: This study showed that puffing parameters, but not device cleaning, have significant effects on carbonyl, phenol and other emissions. Data analysis highlighted the importance of comparing IQOS emissions with an array of commercial cigarettes tested under different puffing regimes before accepting reduced exposure claims., Competing Interests: Competing interests: TE and AS are paid consultants in litigation against the tobacco and e-cigarette industry and are named on one patent for a device that measures the puffing behaviour of e-cigarette users and a patent application for a smoking cessation intervention. TE is also named on a patent application for a smartphone app that determines e-cigarette device and liquid characteristics. All other authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: Although the relationship between smoking and depression has been well-established, little is known about the association between use of e-cigarette and depression, particularly among youth and young adults. This study proposes that e-cigarette dependence, rather than simply use, serves as a potential stressor and may interact with pre-existing vulnerabilities to contribute to depression in youth, consistent with the diathesis-stress theory. This study examines the longitudinal association of vaping dependence and vaping frequency on depression symptoms among youth and young adults who have never smoked cigarettes., Methods: People who used e-cigarettes in the past month who reported never smoking a cigarette (N=1,226) aged between 16 and 25 years were followed longitudinally every 3 months for up to 1 year beginning in 2020. The Penn State E-Cigarette Dependence Index at time t was used to predict depression symptoms assessed using the Center for Epidemiologic Studies Depression Scale at time t+1., Results: A total of 32.1% reported vaping in the past month with the Penn State E-Cigarette Dependence Index score (M=8.5) and a Center for Epidemiologic Studies Depression Scale score (M=15.8). Higher vaping dependence scores were significantly associated with increased depression symptoms scores at follow-up among youth and adults (β=0.08; 95% CI=0.01, 0.15), controlling for baseline depression symptom scores and covariates. Although vaping dependence was highly associated with vaping frequency level, no significant association between the frequency of vaping and depression was found (β= -0.33; 95% CI= 1.21, 0.54)., Conclusions: These results are consistent with the diathesis-stress model of the relationship between substance use and depression. Vaping dependence but not vaping frequency was associated with increased depressive symptoms among people who never smoked cigarettes., (Copyright © 2023 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Nicotine form (freebase/protonated) and nicotine flux (rate at which nicotine is emitted) are two factors that can affect the dose of nicotine inhaled by individuals using electronic nicotine delivery systems (ENDS) because they can influence puffing behavior. The nicotine dose for each puff also is directly proportional to nicotine flux (i.e., dose/puff=nicotine flux*puff duration). This study examines the effect of nicotine form and flux on puffing parameters and mouth-level nicotine exposure., Methods: Thirty-two dual ENDS and combustible cigarette participants completed five visits that differed by nicotine form (freebase or protonated) and nicotine flux (14 or 35µg/sec); a zero-nicotine condition was a negative control. Participants used a Subox Mini C ENDS, powered at 20W, during a 10-puff directed bout (B1) followed by a one-hour ad libitum bout (B2). Puffing parameters and mouth-level nicotine exposure were assessed using the American University of Beirut REALTIME instrument., Results: Relative to protonated nicotine, freebase nicotine was associated with lower total puff duration (puff duration*number of puffs), lower flow rate in B1, lower liquid consumption, and lower mouth-level nicotine exposure. Increasing nicotine flux from 14 to 35µg/sec was associated with lower total puff duration in both bouts, as well as lower liquid consumption. Increasing nicotine flux was associated with higher mouth-level nicotine exposure in B1 only., Conclusion: ENDS with protonated nicotine may enhance nicotine exposure by promoting longer puffing and thus greater dose delivered. This work highlights the importance of accounting for interactions between nicotine form and flux when considering nicotine regulation for ENDS., Competing Interests: Declaration of Competing Interest The authors declare the following competing financial interest: Drs. Shihadeh and Eissenberg are paid consultants in litigation against the tobacco industry and the ENDS industry and are named on one patent for a device that measures the puffing behavior of ENDS consumers and on a patent application for a smoking cessation intervention. Dr. Eissenberg is also named on another patent application for a smartphone app that determines ENDS device and liquid characteristics., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Introduction: Between 2015 and 2018, Canada banned menthol cigarettes. This study pooled data from two pre-post cohort studies (the Ontario Menthol Ban Study, and the International Tobacco Control Policy Evaluation (ITC) Canada Survey, conducted in seven provinces) to derive more precise estimates of the impact of Canada's menthol ban on quitting and to apply these estimates to project the impact of a menthol ban in the USA., Methods: Weighted multivariable logistic analyses compared post-ban quit success of menthol smokers with non-menthol smokers (for daily smokers and for all (daily + non-daily) smokers), controlling for sex, age, ethnicity, education, baseline smoking status, baseline cigarettes per day and study regions. Projections to the USA were created by multiplying the effect size of the Canadian menthol ban on quitting (percentage of increased quitting among menthol smokers) by the number of menthol smokers overall and among African Americans, from the 2019 National Survey on Drug Use and Health., Results: After the menthol cigarette ban, menthol smokers were more likely than non-menthol smokers to have quit smoking among daily smokers (difference=8.0%; 95% CI: 2.4% to 13.7%,p=0.005) and all (daily+non-daily) smokers (difference=7.3%; 95% CI: 2.1% to 12.5%,p=0.006). The projected number of smokers who would quit after a US menthol ban would be 789 724 daily smokers (including 199 732 African Americans) and 1 337 988 daily+non-daily smokers (including 381 272 African Americans)., Conclusions: This pooled analysis of Canada's menthol cigarette ban provides the foundation for estimating the impact of menthol bans in the USA and other countries. Projections suggest that a US menthol cigarette ban would have a substantial impact on increasing quitting., Competing Interests: Competing interests: GTF has served as a paid expert witness or consultant for governments defending their country’s policies or regulations in litigation. He also served as a member of the Brazil Health Regulatory Agency (ANVISA) 2014 Working Group on Tobacco Additives. He has also served as a member of the Expert Group for Article 9 (Regulation of the contents of tobacco products) and Article 10 (Regulation of tobacco product disclosures) of the WHO Framework Convention on Tobacco Control. KMC has received payment as a consultant to Pfizer, for service on an external advisory panel to assess ways to improve smoking cessation delivery in healthcare settings. He has also served as a paid expert witness in litigation filed against cigarette manufacturers. TE is a paid consultant in litigation against the tobacco industry and also the electronic cigarette industry, and is named on a patent for a device that measures the puffing behaviour of electronic cigarette users and patent application for a smoking cessation intervention. TE and EKS are named on a patent application for a smartphone app that measures the characteristics of electronic cigarette devices and e-liquids., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The U.S. Food and Drug Administration proposed new product standards that would ban characterizing flavors (other than tobacco) in cigars. To inform this regulatory action, we compared physiological effects, use behavior, and subjective effects of four popular cigar flavors in cigar-naïve young adult cigarette smokers. Across five laboratory visits, participants ( n = 25) used and evaluated own brand (OB) cigarettes or Black & Mild cigars (original, wine, apple, and cream flavors). Linear mixed models tested differences in saliva nicotine, exhaled carbon monoxide (CO), heart rate (HR), blood pressure (BP), puff topography, and subjective effects ( p < .05). Compared to all cigars, OB resulted in higher nicotine boost (953 vs. < 300 ng/ml) and lower CO boost (4 vs. 8-9 ppm). Nicotine boost for original cigars (283 ng/ml) was significantly higher than wine (190 ng/ml). All products significantly increased HR/BP relative to baseline, but across time wine and apple cigars were associated with significantly lower HR than OB and BP effects varied. Relative to OB, participants took approximately 0.5 s longer puffs for all cigars and took significantly larger puffs (+ 21%-24%) of original, wine, and apple cigars. OB was rated more positively than all cigars, which had similar subjective effects. Wine cigars were disliked most and were less effective in reducing tobacco abstinence symptoms than OB; cream cigars were harsher and had stronger flavor intensity than original. The consistency in toxicant exposure, use behavior, and subjective effects across cigar flavors, including original, highlights the need for product standards to interpret characterizing flavors subject to prohibition broadly. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Background: Research is inconclusive on the effectiveness of electronic nicotine delivery systems (ENDS) as cigarette cessation aids compared with nicotine replacement therapy (NRT) or non-NRT medication. This study compared the cigarette cessation rates for ENDS, NRT and non-NRT medication., Method: Population Assessment of Tobacco and Health Study wave 3 cigarette-only users who used ENDS, NRT or non-NRT medication (varenicline and bupropion) to quit smoking between wave 3 and 4 were included. 'Cessation' was defined as being a former cigarette smoker in wave 4. χ 2 , logistic regression, and a sensitivity analysis with Bayes factor assessed the association between quitting smoking and method used., Results: Among 6794 cigarette-only users, 532 used ENDS (n=75), NRT (n=289), non-NRT medication (n=68), or a combination of NRT and non-NRT medication (n=100) to quit smoking between wave 3 and 4. The percentages of quitting smoking among those who used ENDS, NRT, non-NRT medication, and a combination of NRT and non-NRT medication were 16.2% (n=14), 16.1% (n=47), 17.7% (n=13), and 14.8% (n=12), respectively (p=0.97). None of the cigarette-only users who used ENDS to quit smoking became ENDS-only users in wave 4; 37.6% became dual users of ENDS and cigarettes., Conclusion: No differences were found when cessation rates of ENDS, NRT or non-NRT medication were compared. Given uncertainty about the long-term health effect of ENDS and the likelihood of becoming dual users, people who smoke and need assistance quitting should be encouraged to use current Food and Drug Administration-approved cessation methods until more effective methods are developed., Competing Interests: Competing interests: TE is a paid consultant in litigation against the tobacco industry and also the electronic cigarette industry and is named on one patent for a device that measures the puffing behaviour of electronic cigarette users and on another patent for a smartphone app that determines electronic cigarette device and liquid characteristics. The other coauthors declare no conflict of interests., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Electronic nicotine delivery systems (ENDSs) produce an aerosol by heating a liquid that often contains nicotine. The nicotine can be protonated that may make the aerosol easier to inhale than freebase nicotine. This study's purpose is to determine, in cigarette smokers and ENDS users, the effects of three concentrations of protonated nicotine aerosolized at two different power settings. Forty-five participants (22 cigarette smokers and 23 ENDS users) completed some or all of six sessions that varied by liquid nicotine concentration (10, 15, or 30 mg/ml protonated nicotine) and device power (15 or 30 W). Participants took 10 puffs from each product and then used each product for 90 min ad libitum . Plasma nicotine concentration, subjective effects, and puff topography were measured. Results showed increases in plasma nicotine concentration in all conditions, with greater plasma nicotine increases in higher watt, higher nicotine concentration conditions, as well as greater nicotine delivery for ENDS users compared to cigarette smokers. For puff topography, puff duration and volume decreased as nicotine concentration and power increased, and ENDS users took longer and larger puffs than cigarette smokers. Participants rated the higher watt, higher nicotine concentration conditions as harsher and with more throat hit. Overall, these results suggest that device characteristics and liquid constituents interact to influence users' plasma nicotine delivery and should be considered together when regulating ENDS. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Introduction: Electronic cigarettes (ECIGs) heat a nicotine-containing liquid to produce an inhalable aerosol. ECIG power (wattage) and liquid nicotine concentration are two factors that predict nicotine emission rate ("flux"). These factors can vary greatly across devices and users., Aims and Methods: The purpose of this study was to examine ECIG device and liquid heterogeneity in "real world" settings and the association with predicted nicotine flux, nicotine yield, and total particulate matter (TPM) emissions. Past 30-day ECIG users (n = 84; mean age = 23.8 years [SD = 9.6]) reported device and liquid characteristics. Device power was measured via multimeter, device display screens, or obtained via labeling. Liquid nicotine concentration was obtained via labeling or through chemical analysis. Predicted nicotine flux, nicotine yield, and TPM associated with 10 4-second puffs were calculated for participants' primary devices., Results: Participants' primary devices were box mods (42.9%), disposable vapes (20.2%), and pod mods (36.9%). Most participants (65.5%) reported not knowing their primary device wattage. Rebuildable/box mods had the greatest power range (11.1-120.0 W); pod mod power also varied considerably (4.1-21.7 W). Unlike device wattage, most participants (95.2%) reported knowing their liquid nicotine concentration, which ranged from 3.0 to 86.9 mg/ml (M = 36.0, SD = 29.3). Predicted nicotine flux varied greatly across products (range =12.0-160.1 μg/s, M = 85.6 μg/s, SD = 34.3). Box mods had the greatest variability in wattage and predicted nicotine flux, nicotine yield, and TPM yield., Conclusions: ECIG device and liquid heterogeneity influence nicotine and other toxicant emissions. Better measurement of ECIG device and liquid characteristics is needed to understand nicotine and toxicant emissions and to inform regulatory policy., Implications: ECIG device and liquid heterogeneity cause great variability in nicotine flux and toxicants emitted. These data demonstrate the need to examine device and liquid characteristics to develop empirically informed, health-promoting regulatory policies. Policies may include setting product standards such that ECIG products cannot (1) have nicotine fluxes much greater than that of a cigarette to decrease the risk of dependence, (2) have nicotine fluxes that are very low and thus would have minimal appeal to cigarette smokers and may serve as starter products for youth or nontobacco users, and (3) emit large amounts of particulate matter and other toxicants., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Co-use of tobacco and cannabis and dual use of cigarettes and e-cigarettes are very common among young adults. However, it is unclear whether co-use of cigarettes, e-cigarettes, and/or cannabis is associated with higher levels of nicotine dependence than cigarette-only use. We investigated the relationship between cigarette/nicotine dependence and co-use of tobacco and cannabis among 4 groups of cigarette smokers aged 18-35: cigarette-only smokers, cigarette-e-cigarette (CIG-ECIG) co-users, cigarette-cannabis (CIG-CAN) co-users, and cigarette-e-cigarette-cannabis (CIG-ECIG-CAN) co-users., Methods: Data were from a 2018 cross-sectional survey based on a national convenience sample of smokers aged 18-35 ( n  = 315). Cigarette/nicotine dependence was measured by the Fagerstrom Test of Nicotine Dependence (FTND) and e-cigarette dependence was measured by the Penn State E-cigarette Dependence Index. Bivariate analyses examined sociodemographic and tobacco/other substance use characteristics by co-use status and multivariable linear regression assessed the relationship between co-use and nicotine dependence., Results: In the sample, 27.6% were cigarette-only smokers, 24.8% were CIG-ECIG, 27.6% were CIG-CAN, and 20.0% were CIG-ECIG-CAN co-users. Significant differences were observed in sociodemographic and tobacco/other substance use characteristics by co-use status. E-cigarette co-users had low e-cigarette dependence, but moderate FTND scores. In adjusted analyses, only CIG-ECIG co-use was associated with higher FTND scores compared to cigarette-only smoking. However, CIG-ECIG and CIG-ECIG-CAN co-use were associated with higher FTND scores compared to CIG-CAN co-use., Conclusions: Co-use of cigarettes and e-cigarettes was associated with greater nicotine dependence among smokers aged 18-35. Additional research is needed to understand the underlying mechanisms of these relationships and inform prevention efforts.

Introduction: The combination of electronic nicotine delivery systems (ENDS) device and liquid characteristics affect user nicotine and toxicant exposure, however population-level national survey studies have not reported device and liquid features jointly nor in detail. We examined combinations of characteristics of devices and liquids used by adult ENDS users., Methods: U.S. adults (21+) using ENDS at least five days/week (n = 1,179) completed an online survey in 2020 and uploaded photos of their most used device and liquid. Device/liquid combinations were analyzed to determine and describe the most common pairings. Data were weighted to the U.S. population of adult daily ENDS users., Results: Five device/liquid combinations accounted for 87 % of those reported. The most prevalent combination, reported by 36.2 %, was re-useable devices with adjustable settings and a tank refilled with a free-base nicotine liquid with a median nicotine concentration of 5.2 mg/mL. The second most frequent combination - re-usable devices with no adjustable settings and a nicotine salt liquid in a disposable pod or cartridge - was reported by 22.8 % and the median nicotine concentration was 49.4 mg/mL. Wattage, voltage and resistance varied across device/liquid combination. Overall, 66.5 % refilled their device's tank or pod and 64.2 % had the ability to manipulate device characteristics (power, airflow, and/or coil)., Conclusions: Analyzing ENDS device/liquid combinations rather than each separately can allow researchers to better evaluate relationships between use and key outcomes, such as quitting cigarettes and abuse liability. Additional research may reveal whether certain combinations are more effective at helping smokers quit and which device/liquid combinations should remain on the market., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This work was supported by NIDA and the FDA Center for Tobacco Products (CTP) under award number U54DA036105. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the Food and Drug Administration., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Although overall health in the United States (US) has improved dramatically during the past century, long-standing health inequities, particularly the unequal and unjust burden of tobacco-related disease and death among racialized populations, persist. A considerable gap exists in our understanding of how commercial tobacco product regulations and policies cause and/or exacerbate race-based health inequities among Black/African American (B/AA) and Indigenous American people. The purpose of this paper is to 1) describe how existing US commercial tobacco regulatory policies may contribute to structural racism and undermine the full benefits of tobacco prevention and control efforts among B/AA and Indigenous American groups; and 2) initiate a call to action for researchers and regulators of tobacco products to examine policies using an equity lens. These actions are imperative if empirically-informed regulation of commercial tobacco products is to address health equity., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The JUUL electronic cigarette (e-cigarette) remains popular in the USA and has a big prevalence among youth. In response to the popularity of JUUL and similar devices among youth, the US Food and Drug Administration issued in February 2020 an enforcement policy to remove all flavoured cartridge/pod-based e-cigarettes from the market except for tobacco and menthol. Subsequent studies showed that some users of the now-removed flavoured JUUL pods (especially cool mint) switched to menthol-flavoured JUUL pods with similar satisfaction., Methods: We quantified menthol, nicotine, propylene glycol (PG) and vegetable glycerol (VG) in JUUL pod samples (Menthol, Classic Menthol and Cool Mint) that were purchased in 2017, 2018 and 2020 (only Menthol) to evaluate composition differences before and after the enforcement policy. We also analysed the samples to detect other cooling agents using a screening gas chromatography-mass spectrometry headspace method that we developed for this purpose., Results: Menthol concentration was significantly higher in 2020 products than in products from prior years. Moreover, other cooling agents varied across pods. The PG/VG volume ratio was 27/63 in all pods examined., Conclusion: This study highlights how regulations intended to reduce e-cigarette prevalence among youth may influence changes in tobacco product characteristics in ways that regulators may not have foreseen., Competing Interests: Competing interests: TE and AS are paid consultants in litigation against the tobacco and e-cigarette industry and are named on one patent for a device that measures the puffing behaviour of e-cigarette users and another patent application for a smoking cessation intervention. TE is also named on a patent application for a smartphone app that determines e-cigarette device and liquid characteristics., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Recent regulations have banned all flavors except menthol/mint and classic tobacco from pod-based e-cigarette devices such as JUUL. However, menthol/mint flavor can present a potential risk given its increasing popularity among young people in the US and its puffing and nicotine-enhancing properties. This study examines the impact of menthol/mint flavor manipulation on users' puffing behavior, subjective experience, and nicotine exposure among young people., Methods: JUUL users (n = 33, 18-24 years) attended two 60-min ad libitum e-cigarette use sessions (menthol/mint flavor vs. classic tobacco flavor) in a cross-over design. Puff topography and plasma nicotine concentration were measured, and participants completed subjective experience questionnaires., Results: Following the use of the menthol/mint-flavored pod, increases were observed in measures of satisfaction, pleasurable/interest to use, willingness to use again, enjoyment, urge to vape, product appeal, taste, and concentration (p < .05 for all). For example, compared to the classic tobacco flavor, participants experienced significantly more satisfaction of the product (4.24 vs. 3.09; p = .001) and sensation enjoyment of the product (3.55 vs. 2.48; p = .002) when using the menthol/mint flavor. While means of the plasma nicotine boost and puff parameters were lower in the classic tobacco condition compared to the menthol/mint flavor condition, no statistical significance was observed between the two conditions (p > .05 for all)., Conclusions: Results of this pilot study suggest that menthol/mint-flavor increases e-cigarette users' subjective experience significantly. Regulating menthol/mint flavor is a potentially promising strategy to curb e-cigarette use among young people., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: The extent to which use of electronic nicotine delivery systems (ENDS) for smoking reduction leads to cigarette abstinence in smokers with no plans to quit smoking is unclear. This exploratory analysis examined the effects of ENDS delivering different amounts of nicotine on cigarette abstinence up to 24-week follow-up, in comparison to placebo or a behavioral substitute., Methods: This four-arm parallel-group, randomized, placebo-controlled trial took place at two academic medical centers in the United States (Penn State Hershey and Virginia Commonwealth University). Participants were current adult smokers (N = 520) interested in reducing but not planning to quit. They received brief advice and were randomized to one of four 24-week conditions, receiving either an eGo-style ENDS paired with 0, 8, or 36 mg/ml nicotine liquid (double-blind) or a cigarette-shaped tube, as a cigarette substitute (CS). Self-reported daily cigarette consumption and exhaled carbon monoxide (CO) were measured at all study visits. Outcomes included intent-to-treat, self-reported 7-day cigarette abstinence, biochemically confirmed by exhaled CO at 24 weeks after randomization., Results: At 24 weeks, significantly more participants in the 36 mg/ml condition (14/130, 10.8%) than in the 0 mg/ml condition (1/130, 0.8%) and the CS condition (4/130, 3.1%) were abstinent (relative risk = 14 [95% CI = 1.9-104.9] and 3.5 [95% CI = 1.2-10.4], respectively). The abstinence rate in the 8 mg/ml condition was 4.6% (6/130)., Conclusions: When smokers seeking to reduce smoking tried ENDS, few quit smoking in the short term. However, if smokers continued to use an ENDS with cigarette-like nicotine delivery, a greater proportion completely switched to ENDS, as compared with placebo or a cigarette substitute., Implications: The extent to which use of electronic nicotine delivery systems (ENDS) for smoking reduction leads to cigarette abstinence in smokers with no plans to quit smoking was unclear. This randomized trial found that ENDS with nicotine delivery approaching that of a cigarette are more effective in helping ambivalent smokers to quit cigarette smoking., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: E-cigarette liquid nicotine concentrations typically are labeled as mg/mL or percent, which poorly convey nicotine strength to users. We evaluated whether four novel nicotine concentration labels better convey information about nicotine strength and addictiveness., Methods: Adolescents and young adults (N = 826) completed an online survey in 2020. Participants rated nicotine concentrations (3, 6, 18, 30, 40, and 50 mg/mL) from "no nicotine" to "very high nicotine" communicated using current market labels (mg/mL, percent) and four new labels (text-based, caution sign-shaped, horizonal stoplight, vertical thermometer) which used color, symbols, and verbal strength descriptors. Participants reported on perceived addictiveness for all labels viewed and rank-ordered labels on perceived ability to convey information accurately., Results: Participants ranked the vertical (77%) and horizontal (70%) labels in first or second place and mg/mL (59.1%) and percent (47.2%) in last or second-to-last place. All new labels conveyed nicotine strength more accurately than did market labels (M[SD] correct of 6: percent = 1.50[1.08]; mg/mL = 2.14[1.52]; caution = 5.23[1.37]; vertical thermometer = 5.28[1.51]; text = 5.33[1.36]; horizontal stoplight = 5.47[1.14]), with the horizontal label also outperforming the thermometer and caution labels. Underestimating nicotine strength was uncommon among all new labels (4.7-6.8%). The new labels also were associated with increased perceived addictiveness at higher concentrations (30, 40, and 50 mg/mL), although the thermometer label underperformed the others. When considering perceived nicotine strength, rates of strength underestimates, perceived addictiveness, and rank ordering, the horizontal stoplight label performed best., Conclusions: Novel labeling could improve understanding of nicotine strength and e-cigarette-related risk., Implications: Extending prior research showing that adolescents and young adults who use Electronic Nicotine Delivery Systems (ENDS) have difficulty understanding nicotine concentrations labeled using mg/mL and percent nicotine, the current study demonstrates that novel nicotine concentration labels can improve understanding of nicotine strength and influence perceptions of addictiveness among young ENDS users. While four novel labels were tested, each outperforming current market labeling, the novel label that resembles a horizontal stoplight performed best. The study provides proof-of-concept that creating an easy-to-understand nicotine concentration label is possible and that new labeling better conveys information about nicotine strength and addictiveness., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Cigars are available in a variety of flavors that may impact uptake and use, but little is known about how different flavors affect abuse liability. This study used 3 behavioral economic tasks to examine abuse liability of Black & Mild cigars differing in flavor among young adult cigarette smokers. Participants were 25 cigar-naïve young adults (aged 18-25 years) who smoked ≥ 5 cigarettes/day. In 5 Latin square-ordered laboratory visits, participants completed 3 abuse liability tasks (drug purchase task, cross-price purchase task, and multiple-choice procedure) for each of 4 cigar flavors (original, cream, wine, or apple) and own-brand cigarettes. In the drug purchase task, relative to own-brand cigarettes, all cigar flavors were associated with lower abuse liability using most measures (intensity, breakpoint, maximum total tobacco expenditure for 1 day [ p s < .05]), although only wine-flavored cigars scored significantly lower using 1 measure (price at maximum total tobacco expenditure for 1 day). When cigars and cigarettes were available concurrently in the cross-price purchase task, all cigar flavors functioned as substitutes for cigarettes. Using the multiple-choice procedure, crossover points for wine- (mean = $0.61) and apple-flavored cigars (mean = $0.71) were significantly lower than own-brand cigarettes (mean = $0.86) and original-flavored cigars (mean = $1.00); no significant differences existed between own-brand cigarettes and original-flavored cigars. Thus, whereas abuse liability may be highest for participants' own-brand cigarette, young adult smokers may be willing to use flavored cigars. Furthermore, abuse liability varies by cigar flavor, with original- and cream-flavored cigars appearing to have the highest abuse liability. Characterizing flavors and flavor additives in cigars represent an important tobacco regulatory target. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Background: E-cigarette device and liquid characteristics, such as electrical power output and liquid nicotine concentration, determine the rate at which nicotine is emitted from the e-cigarette (i.e., nicotine flux), and thus are likely to influence user nicotine dependence. We hypothesize that nicotine flux would be associated with the E-cigarette Dependence Scale (EDS) among pod-based and disposable e-cigarette products., Methods: Data were obtained from online panel participants between 18 and 65 years of age, who had indicated that they were either former or current e-cigarette users and resided within the United States (N = 1036). To be included in these analyses, participants had to provide information regarding device type (pod-based or disposable), power (watts), and nicotine concentration (mg/mL), from which we could determine nicotine flux (µg/s) (N = 666). To assess the relationship between nicotine flux and EDS, a series of multivariable linear regressions were conducted. Each model was separated by device type and adjusted for by age and past 30-day e-cigarette use., Results: Greater nicotine flux was associated with higher EDS scores among pod-based e-cigarette users (beta = 0.19, SE = 0.09, p-value = 0.043), but not users of disposable e-cigarettes. Neither power nor nicotine concentration were associated with EDS scores among users of either e-cigarette device type., Conclusion: Results support the hypothesis that nicotine flux is positively associated with nicotine dependence in a sample of current users of pod-based and disposable e-cigarettes., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Electronic cigarette (e-cigarette) use continues to grow with most users reporting concurrent cigarette smoking, but few studies have focused on tobacco use and toxicant exposure among naturalistic dual-using populations. This controlled clinical laboratory study examined how dual versus exclusive use of e-cigarettes and cigarettes and no tobacco/nicotine affected behavioral, physiological, and subjective measures among current dual users. Twenty-two participants identifying as cigarette (≥ 10 cigarettes per day [CPD]) and e-cigarette (≥ 3 days/week) users of "cig-a-like" e-cigarettes completed four 5-day outpatient conditions, which differed by their own brand of products used ad libitum: (a) cigarette and e-cigarette (dual), (b) cigarette-only, (c) e-cigarette-only, and (d) no tobacco/nicotine. Primary outcomes included daily tobacco use, expired air carbon monoxide (CO), and urinary cotinine and NNAL. Linear mixed models with pairwise comparisons (Bonferroni corrected) were performed (p < .05). CPD did not differ significantly between dual and cigarette-only use, but e-cigarette use and liquid consumed increased significantly during e-cigarette-only relative to dual use. Relative to dual use, expired air CO did not differ during cigarette-only and was significantly lower during e-cigarette-only use. Urinary cotinine was significantly lower during e-cigarette-only use relative to dual and cigarette-only use, while urinary NNAL did not differ between the nicotine-containing conditions. In summary, among current dual users, e-cigarettes in combination with cigarettes did not reduce CPD relative to exclusive cigarette use or toxicant exposure relative to exclusive use of either product. However, exclusive e-cigarette use did reduce CO and cotinine, highlighting the benefits of cigarette cessation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Introduction: In 2018, the United States Food and Drug Administration (FDA) required that electronic cigarette (e-cigarette) manufacturers, packagers, importers, distributors, and retailers display an addictive or alternate warning statement on e-cigarette visual advertisements. Few studies have investigated the FDA-mandated and other warnings on social media. This study examined the prevalence and content of warning statements in e-cigarette-related YouTube videos., Methods: In 2019, The Virginia Commonwealth University Center for the Study of Tobacco Products conducted bi-monthly (February-June) YouTube searches by relevance and view count to identify e-cigarette-related videos. Overall, 178 videos met the inclusion criteria. Staff coded each video for the presence of a visual/verbal warning statement, warning statement type (eg, FDA-mandated, addiction/tobacco, safety/toxic exposure, health effects), sponsorship, and tobacco product characteristics. A data extraction tool collected the video URL, title, upload date, and number of views, likes/dislikes, and comments., Results: Only 5.1% of videos contained FDA-mandated and 21.9% contained non-mandated warnings. All videos with FDA-mandated and 46.2% of non-mandated warnings were represented visually. Only 13.1% of industry-sponsored videos uploaded after the mandate effective date had an FDA-mandated warning statement and videos with FDA-mandated and non-mandated (v. no) warnings had significantly fewer views, likes, dislikes, and comments. Among all non-mandated warnings, 31.3% featured an addiction/tobacco, 18.8% a safety/toxic exposure, and 37.5% a health effects warning., Conclusions: The prevalence of FDA-mandated warning statements in e-cigarette related YouTube videos was low. FDA enforcement of the warning statement mandate on YouTube could increase the public's understanding of the addictive nature of nicotine in e-cigarettes., Implications: The FDA has the authority to regulate the advertisement and promotion of e-cigarettes on the Internet. These data can inform future FDA requirements related to the language content and visual representation of addiction/tobacco, safety/exposure, and health effects warning statements that appear in YouTube videos and other visual social media popular among young people. Such data would help consumers make informed decisions about purchasing e-cigarette products, using e-cigarettes, and avoiding unintentional harm related to e-cigarettes. In addition, these data may help social media platforms make decisions on whether they will prohibit advertisements that promote or facilitate the sale of tobacco products., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: E-cigarette e-liquid nicotine concentrations typically are labeled as mg/mL or percent nicotine. We examined whether these metrics accurately convey nicotine strength to young e-cigarette users and if youth can compare concentrations presented in mg/mL and percent nicotine., Aims and Methods: Eight hundred and twenty-one adolescent and young adult e-cigarette users participated in the survey. Participants rated nicotine concentration strengths presented as mg/mL (0-60 mg/mL) and percent nicotine (0%-6%) from "no nicotine" to "very high nicotine." Participants also viewed pairs of nicotine concentrations (eg, 18 mg/mL vs. 5%) and indicated which concentration was stronger or if the concentrations were equivalent., Results: On average, participants correctly identified 5.92 (2.68) of 18 nicotine strengths, correctly identifying strengths labeled as mg/mL (3.47 [2.03]) more often than percent nicotine (2.45 [1.38], p < .001). Excluding nicotine-free, participants rated concentrations presented as mg/mL as stronger, more addictive, and more harmful than equivalent concentrations presented as percent nicotine. Participants seldom correctly identified that one concentration was stronger or that both were equivalent (7.58 [5.88] of 19 pairings), although they more often correctly identified the stronger concentration when it was presented in mg/mL (4.02 [SD = 3.01]) than in percent nicotine (2.53 [2.73], p < .001). The most consistent predictor of correct answers on these tasks was familiarity with using both products labeled as mg/mL and labeled as percent nicotine., Conclusions: Young e-cigarette users had difficulty understanding nicotine concentrations labeled using the most common metrics, raising concerns about inadvertent exposure to high nicotine levels and suggesting that a more intuitive labeling approach is needed., Implications: This study extends prior work showing that young e-cigarette users often are uncertain whether the e-liquids they use contain nicotine by demonstrating that adolescents and young adults have difficulty understanding nicotine concentrations labeled using the two most common metrics (mg/mL and percent nicotine). Errors generally underestimated nicotine strength, and users were not able to accurately compare nicotine concentrations presented as mg/mL and percent nicotine. Difficulty understanding labeling metrics persisted even after accounting for user characteristics like age and vaping experience, suggesting that a novel, easy to understand labeling system is needed to convey information about nicotine strength accurately., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The prevalence of e-cigarette use among youth and young adults has increased markedly in recent years; however, little is known about young people's perceptions of e-cigarette addiction. This study examines factors associated with self-reported addiction to e-cigarette use among this population., Methods: In 2018, 1048 Canadians aged 16-25 years were recruited through online social media platforms to complete a survey. Quota sampling was used to oversample regular e-cigarette users (vaping at least weekly); these 578 regular users were included in this analysis. Self-perceived addiction was assessed by asking participants if they felt they were 'very', 'somewhat' or 'not at all' addicted to e-cigarettes. A proportional odds model was employed to identify factors associated with the ordinal outcome., Results: Almost half of regular users perceived themselves to be 'not at all addicted', 41% felt they were 'somewhat addicted' and 13% felt they were very addicted to e-cigarettes. Women, former cigarette smokers, daily vapers and those vaping for more than a year were more likely to report higher levels of perceived addiction. Similarly, high sensation-seeking youth, those reading blogs and websites about vaping, those frequently dripping and those using higher nicotine strengths had a greater likelihood of higher perceived addiction than their respective counterparts., Conclusion: More than half of youth and young adult regular e-cigarette users felt they had some level of addiction. The findings identify possible opportunities for targeted programming for education and treatment, as well as potential opportunities for policy change such as maximum allowable nicotine strengths., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Most users of electronic cigarettes (e-cigarettes) report initiating use to quit combustible cigarettes. Nevertheless, high levels of dual use (i.e., using both combustible cigarettes and e-cigarettes) occur among adults. Using formative data from in-depth interviews and employing learner verification, we adapted an existing, validated self-help smoking-cessation intervention (Stop Smoking for Good; SSFG) to create a targeted intervention for dual users, If You Vape: A Guide to Quitting Smoking (IYV). In Phase I, in-depth interviews ( n = 28) were conducted to assess relevance of the existing SSFG materials (10 booklets, nine pamphlets) and identify new content for the booklets. Next, for Phase II, learner verification interviews ( n = 20 dual users) were conducted to assess their appeal and acceptability. Several key themes emerged from the Phase I in-depth interviews. Findings led to the inclusion of e-cigarette-specific strategies used by successful quitters such as gradually reducing nicotine levels, switching from tobacco flavor to alternative flavors, and limiting e-cigarette use to places one would normally smoke (i.e., not expanding use). Suggestions from Phase II learner verification included broadening the visual appeal for a younger, more diverse demographic, expanding tips for quitting smoking via e-cigarettes, and expanding terminology for e-cigarette devices. Beginning with an efficacious self-help intervention, we used a systematic process to develop a version specifically for dual users.

Purpose: Waterpipe (WP) smoking patterns and setting can result in a unique trajectory of nicotine dependence (ND) compared with cigarette smoking. This longitudinal study compared the development of ND symptoms among adolescent WP and cigarette smokers., Methods: A cohort of 647 eighth and ninth graders in Lebanon were followed over 5 years. This study was based on 283 current exclusive WP and 146 current exclusive cigarette smokers. Kaplan-Meier survival analyses were conducted to evaluate 50% cumulative probability for the development of initial Hooked on Nicotine Checklist symptoms and the International Classification of Diseases, 10th revision (ICD-10) ND., Results: An initial Hooked on Nicotine Checklist symptom was endorsed by 59% of WP and 50% of cigarette smokers after smoking onset. Among those, 50% of both WP and cigarette smokers did so within 9.7 and 18.5 months, respectively. Approximately 28% of WP smokers and 22% of cigarette smokers developed ICD-10 ND. Among those, 50% of both WP and cigarette smokers did so within 15 and 22 months, respectively. The most common first to fourth ICD-10 criteria reported by WP smokers were "a strong desire to use tobacco," "difficulties in controlling tobacco taking behavior," "neglect of alternative pleasure," and "use despite harm." The most common first to fourth ICD-10 criteria reported by cigarette smokers were "a strong desire to use tobacco," "difficulties in controlling tobacco taking behavior," "withdrawal," and "tolerance"., Conclusions: Compared with adolescent cigarette smokers, initial ND symptoms and ICD-10 ND can develop sooner after starting to smoke and progress more rapidly among adolescent WP smokers. Developing, implementing, and evaluating intervention programs with adolescent WP smokers should be guided by the WP-specific trajectory of ND., (Copyright © 2020 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.)

Introduction: Little is known about differences in tobacco product dependence among people who use two tobacco products versus one. Self-reported product dependence among individuals using cigarettes only, electronic nicotine delivery systems (ENDS) only, and both cigarettes and ENDS (dual users) was compared., Method: PATH Wave 3 data were collected between 2015 and 2016. We used 11 Wisconsin Inventory of Smoking Dependence Motives items to assess cigarette and ENDS dependence, averaged to generate Cigarette Dependence (CD) and ENDS Dependence (ED) scores. Linear regression models were used to assess the association between tobacco use groups and the two dependence scores., Results: Our analytic sample included 5538 (91.5 %) cigarette only, 399 (6.7 %) ENDS only, and 108 (1.8 %) dual users. There was no difference in CD between cigarette only and dual users. ENDS only users' ED (2.11, SE = 0.05) was higher than dual users' ED (1.67, SE = 0.04) (p < 0.05). Dual users' mean ED (1.70, SE = 0.09) was significantly lower than their CD (3.03, SE = 0.11) (p < 0.001), and ENDS only users' ED (2.34, SE = 0.05) was significantly lower than cigarette only users' CD (2.94, SE = 0.02) (p < 0.001)., Conclusion: While there was no difference in CD between dual and cigarette only users, dual users' ED was lower than that for ENDS only users. ENDS appeared to produce less dependence than cigarettes among dual users. Given the high nicotine concentration ENDS products that entered the market after PATH Wave 3 data were collected, future research should examine ED among ENDS only and dual users., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)

Tobacco use delivers nicotine, tobacco-specific nitrosamines (TSNAs), volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs), which are metabolized and excreted in urine offering useful biomarkers of exposure. Previous studies compared individual toxicants across tobacco users. Based on a group of biomarkers, cluster analysis was used to define tobacco toxicant exposure profiles. Clusters with distinct exposure profiles, were determined and described, based on levels of urinary biomarkers of exposure to nicotine, TSNAs, VOCs, and PAHs among a national sample of current, established, adult tobacco users, and examine the association of use behavior and cluster membership. The PATH Biomarker Wave 1 data were analyzed. Current established tobacco users with complete urinary biomarker data were included (N = 6724). User groups included cigarette smokers, users of electronic cigarette (ECIG), smokeless tobacco (SLT), and dual and poly tobacco users. Cluster analysis, pairwise comparisons, and multinomial logistic regression were conducted. Cigarette smokers were primarily in clusters with high biomarker concentrations across all groups, but actual concentrations were associated with smoking quantity. A cluster with high TSNAs but low levels of PAHs and VOCs was heavily populated by SLT users. Exclusive ECIG users, depending on use frequency, were predominantly in clusters with low biomarker concentrations, except for one cluster that had relatively high TSNAs. Clusters heavily populated by dual and poly tobacco users were the same as those heavily populated by cigarette smokers. Ten exposure profiles (clusters) were determined and linked to tobacco use behavior. Findings could inform future research and policy initiatives., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Tobacco control policies have helped to reduce the health, social, and economic burden of commercial tobacco use worldwide. Little is known about the long-term impact of regulatory policies and functioning bodies that make recommendations to inform policies. The Tobacco Products Scientific Advisory Committee (TPSAC) of the U.S. Food and Drug Administration (FDA) was formed in 2009 to evaluate the safety, health, and dependence of tobacco products and provide related advice and recommendations to the FDA and the Secretary of Health and Human Services. This article describes the first 10 years of the TPSAC activities and reflects on the impact of their service on regulatory actions. Methods: We reviewed public documents from the 2010-2019 TPSAC meetings to examine the purposes, TPSAC decisions, public health participation in meetings, and concordance of the TPSAC recommendations with regulatory actions. Meeting agendas, transcripts, public testimony, and presentations were reviewed to obtain this information. Results: Since 2010, the TPSAC held 25 public meetings with 178 speakers who provided oral public testimony. Sixty-four percent of meetings were held from 2010 to 2012, when three congressionally mandated reports were due on the topics of menthol cigarettes, harmful and potentially harmful constituents in tobacco products, and dissolvable tobacco products. Forty-four percent of meetings focused on menthol cigarettes, 32% on modified risk tobacco products, 16% on harmful and potentially harmful constituents, 12% on dissolvable tobacco, and 4% on tobacco addiction/dependence. FDA regulatory actions were largely nonconcordant with voting decisions by TPSAC. Conclusions: The TPSAC has evaluated an enormous amount of science during the first 10 years, but their influence on regulatory policies has been limited. The TPSAC roles and functioning should be reevaluated to determine how TPSAC can better fulfill its mandate to inform the FDA's regulatory decision making, which could ultimately reduce the burden of tobacco use in the United States.

Objectives: The province of Ontario, Canada, banned the use of menthol-flavoured tobacco products as of 1 January 2017. The long-term impact of a menthol ban on smoking behaviour has not been previously evaluated., Methods: Population cohort study with baseline survey conducted September-December 2016 and follow-up January-August 2018 among residents of Ontario, Canada, 16 years old and over who reported current smoking (past 30 days) at baseline survey and completed follow-up (n=913) including 187 reporting smoking menthol cigarettes daily, 420 reported smoking menthol cigarettes occasionally, and 306 were non-menthol cigarette smokers. Relative rates of making a quit attempt and being a non-smoker at follow-up were estimated with Poisson regression controlling for smoking and demographic characteristics at baseline., Results: At follow-up, 63% of daily menthol smokers reported making a quit attempt since the ban compared with 62% of occasional menthol smokers and 43% of non-menthol smokers (adjusted relative rate (ARR) for daily menthol smokers compared with non-menthol smokers: 1.25; 95% CI 1.03 to 1.50). At follow-up, 24% of daily menthol smokers reported making a quit since the ban compared with 20% of occasional menthol smokers and 14% of non-menthol smokers (ARR for daily menthol smokers compared with non-menthol smokers: 1.62; 95% CI 1.08 to 2.42)., Conclusions: The study found higher rates of quitting among daily and occasional menthol smokers in Ontario 1 year after the implementation of a menthol ban compared with non-menthol smokers. Our findings suggest that restrictions on menthol may lead to substantial improvements in public health., Competing Interests: Competing interests: Dr Eissenberg is a paid consultant in litigation against the tobacco industry and is named on a patent application for a device that measures the puffing behavior of electronic cigarette users., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The United States Food and Drug Administration has prioritized understanding the dependence potential of electronic cigarettes (e-cigs). Dependence is often estimated in part by examining frequency of use; however measures of e-cig use are not well developed because of varying product types. This study used an e-cig automatic puff counter to evaluate the value of self-reported e-cig use measures in predicting actual use (puffs)., Methods: Data were collected from a two-site randomized placebo-controlled trial evaluating the effects of e-cigs on toxicant exposure in smokers attempting to reduce their cigarette consumption. Participants randomized to an e-cig condition self-reported their e-cig frequency of use (times per day-one "time" consists of around 15 puffs or lasts around 10 minutes) on the Penn State Electronic Cigarette Dependence Index (PSECDI) and kept daily diary records of the number of puffs per day from the e-cig automatic puff counter. A linear mixed-effects model was used to determine the predictive value of the times per day measure. Correlations were used to further investigate the relationship., Results: A total of 259 participants with 1165 observations of e-cig use were analyzed. Self-reported e-cig use in times per day was a significant predictor of e-cig puffs per day (p < .01). The Spearman correlation between measures was r equal to .58. Examination of individual participant responses revealed some potential difficulties reporting and interpreting times per day because of the difference in use patterns between cigarettes and e-cigs., Conclusion: This study provides evidence that the self-reported PSECDI measure of times per day is a significant predictor of actual frequency of e-cig puffs taken., Implications: Self-reported measures of e-cig frequency of use are predictive of actual use, but quantifying e-cig use in patterns similar to cigarettes is problematic., (© The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objectives: This study examined the effect of pictorial health warning labels (HWLs) on the waterpipe (WP) device on smokers' experience, puffing behaviour, harm perception and exposure to respiratory toxicants., Methods: Thirty WP smokers completed two 45 min ad libitum smoking sessions (WP without HWL vs WP with HWL) in a crossover design study. Exhaled carbon monoxide (eCO) was measured before and after each smoking session. Puff topography was recorded throughout the smoking session, and participants completed survey questionnaires assessing subjective smoking experiences and harm perception., Results: Significant differences were observed in eCO levels between the two study conditions, with lower levels of eCO boost recorded following smoking the WP fitted with HWL (16 ppm) compared with WP without HWL (22.7 ppm). Participants had more puffs, shorter interpuff intervals and a higher total puff volume during smoking the WP without HWL relative to WP with HWL (p values <0.05). We documented enhanced reports of satisfaction, taste and puff liking following smoking the WP without HWL compared with the WP with HWL. WP harm perception was significantly higher among participants after smoking the WP with HWL compared with WP without HWL., Conclusion: This pilot study shows that placing HWL on the WP device is effective in reducing WP smoker's positive experiences, puffing parameters and exposure to carbon monoxide. HWLs lead also to more appreciation of WP harmful effects, making them a promising regulatory approach for addressing the spread of WP smoking among young adults in the USA., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Waterpipe smoking is a method of tobacco consumption that continues to spread globally. In 2002, a ban of tobacco sales was adopted in the Saudi Arabian cites of Mecca and Medina., Aims: This study aimed to examine prevalence of waterpipe and cigarette smoking among students of Taibah University, the biggest in Medina, where the tobacco sales ban has been implemented., Methods: A structured questionnaire was distributed between February and April 2015 to examined tobacco use among Taibah University students., Results: The prevalence of current and ever waterpipe use was 24.2% and 36.04%, respectively, compared with 31.9% and 42.7% for current and ever cigarette smoking. This prevalence is similar to that reported in other Saudi cities where tobacco sales are allowed. Multivariate analysis showed that waterpipe use was higher among senior students; those with pocket money spending of > 500 Saudi Arabia riyal (SAR)/month; and if > 5 individuals were living in the household. In addition, waterpipe use was lower among students with monthly household income of 5000-9000 SAR. In contrast, current cigarette smoking was more frequent in those aged > 22 years; among male students; in those with pocket money spending of > 500 SAR/month; and those who lived away from their parents., Conclusions: Waterpipe and cigarette smoking, despite the ban on tobacco sales, is still common among Taibah University students in Medina, Saudi Arabia., (Copyright © World Health Organization (WHO) 2019. Some rights reserved. This work is available under the CC BY-NC-SA 3.0 IGO license (https://creativecommons.org/licenses/by-nc-sa/3.0/igo).)

Introduction: Sugars are major constituents and additives in traditional tobacco products, but little is known about their content or related toxins (formaldehyde, acetaldehyde, and acrolein) in electronic cigarette (e-cigarette) liquids. This study quantified levels of sugars and aldehydes in e-cigarette liquids across brands, flavors, and nicotine concentrations (n = 66)., Methods: Unheated e-cigarette liquids were analyzed using liquid chromatography mass spectrometry and enzymatic test kits. Generalized linear models, Fisher's exact test, and Pearson's correlation coefficient assessed sugar, aldehyde, and nicotine concentration associations., Results: Glucose, fructose and sucrose levels exceeded the limits of quantification in 22%, 53% and 53% of the samples. Sucrose levels were significantly higher than glucose [χ2(1) = 85.9, p < .0001] and fructose [χ2(1) = 10.6, p = .001] levels. Formaldehyde, acetaldehyde, and acrolein levels exceeded the limits of quantification in 72%, 84%, and 75% of the samples. Acetaldehyde levels were significantly higher than formaldehyde [χ2(1) = 11.7, p = .0006] and acrolein [χ2(1) = 119.5, p < .0001] levels. Differences between nicotine-based and zero-nicotine labeled e-cigarette liquids were not statistically significant for sugars or aldehydes. We found significant correlations between formaldehyde and fructose (-0.22, p = .004) and sucrose (-0.25, p = .002) and acrolein and fructose (-0.26, p = .0006) and sucrose (-0.21, p = .0006). There were no significant correlations between acetaldehyde and any of the sugars or any of the aldehydes and glucose., Conclusions: Sugars and related aldehydes were identified in unheated e-cigarette liquids and their composition may influence experimentation in naïve users and their potential toxicity., Implications: The data can inform the regulation of specific flavor constituents in tobacco products as a strategy to protect young people from using e-cigarettes, while balancing FDA's interest in how these emerging products could potentially benefit adult smokers who are seeking to safely quit cigarette smoking. The data can also be used to educate consumers about ingredients in products that may contain nicotine and inform future FDA regulatory policies related to product standards and accurate and comprehensible labeling of e-cigarette liquids.

Introduction: Prior to the US Food and Drug Administration's (FDA) regulation of electronic cigarettes and warning statements related to nicotine addiction, there was no critical examination of manufacturer/distributor voluntary practices that could potentially inform FDA actions aimed to protect consumers. This study examined the content of warning statements and safety characteristics of electronic cigarette liquid bottles using a national sample., Methods: Research staff randomly selected four electronic cigarette liquid manufacturers/distributors from four US geographic regions. Staff documented the characteristics of product packaging and content of warning statements on 147 electronic cigarette liquids (0-30 mg/ml of nicotine) purchased online from 16 manufacturers/distributors in April of 2016., Results: Data showed that 97.9% of the electronic cigarette liquid bottles included a warning statement, most of which focused on nicotine exposure rather than health. Only 22.4% of bottles used a warning statement that indicated the product "contained nicotine." Of bottles that advertised a nicotine-based concentration of 12 mg/ml, 26% had a warning statements stated that the product "contains nicotine." None of the statements that indicated that the product "contained nicotine" stated that nicotine was "addictive." All bottles had a safety cap and 12% were in plastic shrink-wrap. Fifty-six percent of the websites had a minimum age requirement barrier that prevented under-aged persons from entering., Conclusions: Most manufacturers/distributors printed a warning statement on electronic cigarette liquid bottles, but avoided warning consumers about the presence and the addictiveness of nicotine. Studies are needed to examine manufacturer/distributor modifications to product packaging and how packaging affects consumer behaviors., Implications: These data can inform future FDA requirements related to the packaging and advertising of e-cigarette liquids; regulation related to the content of warning statements, including exposure warning statements, which are not currently mandated; and requirements on websites or language on packaging to help manufacturers adhere to the minimum age of purchase regulation. The data can also be used to help FDA develop additional guidance on the framing of statements on packaging that helps consumers make informed decisions about purchasing the product or protecting young people from use or unintentional exposure to the product.

Introduction: Increased consumption of little cigars and cigarillos (LCCs) among late adolescent and young adult African American smokers is an emerging public health concern. Despite a growing body of epidemiological evidence, there is scant research on systematic variations in LCC use among young adult African Americans. This study aimed to disaggregate African American Black & Mild (B&M) smokers and to identify subgroups of cigarillo smokers' behaviors and associated characteristics., Methods: Using telephone screening data for a NIH-funded clinical laboratory study of toxicant exposure associated with B&M use, latent class analysis (LCA) was used to classify 331 African American B&M smokers' based on daily use, average daily consumption, preference for flavors, preference for product design tips, and product modification behaviors., Results: Results showed five classes, three of which (Daily-Hypers, Daily-Flavored, and Heavy-Daily-Hypers) reflected daily use and average daily consumption rate ranging between 2.7 and 8.9 B&M cigarillos per day. Non-Daily-Hypers and Non-Daily-Flavored classes represented non-daily use patterns and averaged less than 1.0 B&M cigarillo per day. Both sets of classes defined by daily users and non-daily users included smokers who preferred flavored tobacco and who practiced product modification techniques involving hyping and blunting., Conclusions: Latent class analysis is a useful method to detect subtle differences in B&M product preferences and smoking behaviors among African Americans. Study findings highlight the importance of developing tailored interventions that consider within group differences in order to reduce the prevalence of cigarillo smoking among those with the greatest burden., Implications: The current study is the first to identify unique subgroups of African American B&M smokers based on cigarillo use behaviors and associated characteristics. Latent class analyses may prove useful for understanding other subgroups of tobacco users. Current findings concerning patterns of LCC use illustrate how future tobacco cessation and prevention interventions may be tailored for African American smokers., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Cigars remain a widely used tobacco product among adolescent and adult populations. The appeal of a certain type of cigar, the cigarillo, may be enhanced by users' beliefs that their harm potential can be reduced by removing the inner tobacco liner before use (a.k.a. "hyping"). The purpose of this within-subject study was to compare the acute effects of smoking an original cigarillo, a modified ("hyped") cigarillo, and an unlit cigarillo., Methods: Twenty smokers (19 males, 1 female; 19 non-Hispanic blacks, 1 Hispanic "other") of at least 7 Black&Mild (B&M) cigarillos/week and at most 5 cigarettes/day completed the study. All participants reported hyping their cigarillos at least occasionally. Primary outcomes, assessed over two, 30-minute smoking bouts, included plasma nicotine, expired air carbon monoxide (CO) concentration, subjective ratings (product effects, nicotine abstinence symptoms), and puff topography., Results: Mean plasma nicotine concentration increased significantly within (pre- to post-bouts), but not between, original and modified B&M conditions. Mean CO concentration was significantly lower for modified, relative to original, B&M smoking at all post-administration timepoints. Both smoked conditions significantly increased ratings of positive product effects (satisfaction, pleasant) and decreased abstinence symptom magnitude; however, ratings generally did not differ between these conditions. Overall, topography outcomes did not differ between modified and original B&M smoking., Conclusions: Results are consistent with a previous report in that "hyping" may decrease users' CO, but not nicotine, exposure. While these data collectively suggest reduced exposure to CO acutely with engagement in "hyping," longer-term assessments are needed to determine the impact on individual and public health., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Electronic cigarettes (ECIGs) aerosolise a liquid that usually contains propylene glycol and/or vegetable glycerine, flavourants and the dependence-producing drug, nicotine, in various concentrations. This laboratory study examined the relationship between liquid nicotine concentration and plasma nicotine concentration and puffing behaviour in experienced ECIG users., Methods: Sixteen ECIG-experienced participants used a 3.3-Volt ECIG battery attached to a 1.5-Ohm dual-coil 'cartomiser' loaded with 1 mL of a flavoured propylene glycol/vegetable glycerine liquid to complete four sessions, at least 2 days apart, that differed by nicotine concentration (0, 8, 18 or 36 mg/mL). In each session, participants completed two 10-puff ECIG-use bouts (30 s puff interval) separated by 60 min. Venous blood was sampled to determine plasma nicotine concentration. Puff duration, volume and average flow rate were measured., Results: Immediately after bout 1, mean plasma nicotine concentration was 5.5 ng/mL (SD=7.7) for 0 mg/mL liquid, with significantly (p<0.05) higher mean concentrations observed for the 8 (mean=17.8 ng/mL, SD=14.6), 18 (mean=25.9 ng/mL, SD=17.5) and 36 mg/mL (mean=30.2 ng/mL; SD=20.0) concentrations; a similar pattern was observed for bout 2. For bout 1, at 36 mg/mL, the mean post- minus pre-bout difference was 24.1 ng/mL (SD=18.3). Puff topography data were consistent with previous results and revealed few reliable differences across conditions., Discussion: This study demonstrates a relationship between ECIG liquid nicotine concentration and user plasma nicotine concentration in experienced ECIG users. Nicotine delivery from some ECIGs may exceed that of a combustible cigarette. The rationale for this higher level of nicotine delivery is uncertain., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Introduction: Clinical laboratory work among intermittent and daily waterpipe tobacco smokers has revealed significant risks for tobacco dependence and disease associated with waterpipe tobacco smoking (WTS). No studies have compared these groups directly. This study examined whether WTS frequency was associated with differential puff topography, toxicant exposure, and subjective response using a placebo-control design., Methods: Eighty participants reporting WTS of 2-5 episodes (LOW; n = 63) or ≥20 episodes (HIGH; n = 17) per month for ≥6 months completed 2 double-blind, counterbalanced 2-hr sessions that were preceded by ≥12hr of tobacco abstinence. Sessions differed by product smoked ad libitum for 45+ min: preferred brand/flavor of waterpipe tobacco (active) or a flavor-matched tobacco-free waterpipe product (placebo). Outcomes included puff topography, plasma nicotine, carboxyhemoglobin (COHb), and subjective response., Results: HIGH users had more puffs, shorter inter-puff-intervals, and a higher total puff volume for placebo relative to active, as well as relative to LOW users during placebo. Plasma nicotine concentrations increased when smoking active (but not placebo) with no significant differences between groups at 25min post-product administration. COHb increased significantly during all conditions; the largest increase was for HIGH users when smoking placebo. There was some evidence of higher baseline scores for nicotine/tobacco nicotine abstinence symptomology., Conclusions: Higher frequency waterpipe users may be more sensitive to the effects of waterpipe smoke nicotine content. Among HIGH users, higher baseline nicotine/tobacco abstinence symptoms may indicate greater nicotine dependence. These data support continued surveillance of WTS and development of dependence measures specific to this product., (© The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes., Design: Self-reports from cross-sectional Internet and mail surveys. Comparisons of: (a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; (b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); (c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström test for nicotine dependence, the nicotine dependence syndrome scale, the cigarette dependence scale and versions of these scales adapted for e-cigarettes and nicotine gums., Results: Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (≤3 months) users of gums or e-cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers., Conclusions: Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The prevalence of non-cigarette tobacco product use is on the rise across the globe, especially for waterpipes (also known as hookah, narghile, and shisha) and electronic cigarettes (e-cigarettes). The scientific literature reveals that waterpipe tobacco smoking is associated with exposure to a variety of toxicants that can cause short- and long-term adverse health events. In contrast, there is far less evidence of health harms related to e-cigarette use, although the variety of products in this category makes it difficult to generalize. We searched the PubMed database for all publications on waterpipes and e-cigarettes from January 2000 to March 2014. The number of publications on waterpipes rose in a slow, linear pattern during this time, while the number of publications on e-cigarettes showed exponential growth. The different trends suggest there may be more interest in studying a novel nicotine product (the e-cigarette) over a traditional tobacco product (the waterpipe). We posit that, although the specific research needs for these products are different, public health would be served best by a more equitable research approach. Scientists should continue to devote attention to understanding the unknown long-term health effects of e-cigarettes and their potential to serve as harm reduction or smoking cessation tools while simultaneously investigating how to reduce waterpipe smoking given that it exposes users to toxicants known to cause harm to health. Recent regulatory action in the United States, which proposes to include waterpipes and e-cigarettes under some of the same regulations as tobacco cigarettes, makes such research particularly timely.

Introduction: In recent years, a class of products marketed as "tobacco-free" alternatives for the "health conscious user" has become widely available for waterpipe (hookah, narghile, or shisha) smoking. Their adoption may be in part driven by regulations banning tobacco smoking in public places and by an increasing awareness of the hazards of waterpipe tobacco smoking. Although these products are presented in advertising as a "healthier" choice, very little is known about their health effects., Methods: In this study, we compared the effects of smoke generated with tobacco-free and conventional tobacco-derived products on human alveolar cells. Smoke was generated with a smoking machine that precisely mimicked the puffing behavior of 15 experienced waterpipe smokers when they used conventional waterpipe tobacco products of their choice and flavor-matched tobacco-free products. Human alveolar epithelial cells (A549) were treated with particulate matter sampled from the smoke, and the effects on cell cycle, proliferation, and doubling time were measured during the subsequent 72hr., Results: We found that smoke from both types of waterpipe products markedly reduced cell proliferation, caused cell cycle arrest at G0/G1, and increased cell doubling time. There were no significant differences across product in any measure., Conclusion: Tobacco-free and tobacco-based waterpipe products exert substantial and similar deleterious effects on human lung cells. This study adds to the nascent evidence base indicating that except for exposure to nicotine and its derivatives, use of tobacco-free waterpipe products does not present a reduced health risk relative to the use of conventional tobacco-based products.

Cigar smoking is increasingly common among adolescents who perceive cigars as less harmful than cigarettes. This perception of reduced harm is especially true for cigars that are user-modified by removing the tobacco binder through a process called 'freaking'. Little is known about 'freaking' and this multi-study, mixed-methods analysis sought to understand better the rationale and prevailing beliefs about this smoking practice using YouTube videos. In Study 1, we conducted a descriptive content analysis on the characteristics of 26 randomly sampled cigar product modification (CPM) videos posted during 2006-10. In Study 2, a thematic analysis was performed on the transcripts of commentary associated with each video to characterize viewers' comments about video content. Study 1 results revealed that 90% of videos illustrated a four-step CPM technique: 'Loosening the tobacco'; 'Dumping the tobacco'; 'Removing the cigar binder' and 'Repacking the tobacco'. Four themes related to the purpose of CPM were also derived from video content: 'Easier to smoke' (54%), 'Beliefs in reduction of health risks' (31%), 'Changing the burn rate' (15%) and 'Taste enhancement' (12%). Study 2 results concerning the content characteristics of video comments were categorized into three themes: 'Disseminating information/answering questions' (81%), 'Seeking advice/asking questions' (69%) and 'Learning cigar modification techniques' (35%). Favorable comments were more common (81%) compared to unfavorable (58%) and comment content suggested low-risk perceptions and poor understanding of smoking harms. These findings highlight a novel means for youth to access information concerning CPM that may have important implications for tobacco control policy and prevention.

Introduction: A revised indoor air quality law has been implemented in Virginia to protect the public from the harmful effects of secondhand smoke exposure. This legislation contains exemptions that include allowances for smoking in a room that is structurally separated and separately ventilated. The objective of the current study was to examine the impact of this law on air quality in waterpipe cafés, as well as to compare the air quality in these cafés to restaurants that allow cigarette smoking and those where no smoking is permitted., Methods: Indoor air quality in 28 venues (17 waterpipe cafés, five cigarette smoking-permitted restaurants and six smoke-free restaurants (five with valid data)) in Virginia was assessed during 4 March to 27 May 2011. Real-time measurements of particulate matter (PM) with 2.5 μm aerodynamic diameter or smaller (PM2.5) were obtained and occupant behaviour/venue characteristics were assessed., Results: The highest mean PM2.5 concentration was observed for waterpipe café smoking rooms (374 μg/m(3), n=17) followed by waterpipe café non-smoking rooms (123 μg/m(3), n=11), cigarette smoking-permitted restaurant smoking rooms (119 μg/m(3), n=5), cigarette smoking-permitted restaurant non-smoking rooms (26 μg/m(3), n=5) and smoke-free restaurants (9 μg/m(3), n=5). Smoking density was positively correlated with PM2.5 across smoking rooms and the smoke-free restaurants. In addition, PM2.5 was positively correlated between smoking and non-smoking rooms of venues., Conclusions: The PM2.5 concentrations observed among the waterpipe cafés sampled here indicated air quality in the waterpipe café smoking rooms was worse than restaurant rooms in which cigarette smoking was permitted, and state-required non-smoking rooms in waterpipe cafés may expose patrons and employees to PM2.5 concentrations above national and international air quality standards. Reducing the health risks of secondhand smoke may require smoke-free establishments in which tobacco smoking sources such as water pipes are, like cigarettes, prohibited.

Objective: To examine the relationship between adolescents' cigarette smoking experiences and alternative tobacco product (ATP) use., Methods: Multiple indicators and multiple causes (MIMIC) models estimated simultaneously the relationship between cigarette smoking experiences and ATP use among high school students (N=1827) completing the 2009 Virginia Youth Tobacco Survey., Results: Overall, ATP use was associated with adolescents' ever use of cigarettes, early onset of cigarette smoking, cigarettes smoked per day, and peer smoking; however, important model differences between racial/ethnic groups were observed., Conclusions: Prevention and cessation programs might reduce adolescent ATP use by targeting specific characteristics of cigarette smoking.

The International Classification of Diseases and the Diagnostic and Statistical Manual for diagnosing tobacco/nicotine dependence emphasize the dependence-producing drug nicotine. These diagnostic tools have been challenged on grounds of poor predictive validity, and they do not differentiate across various forms of nicotine-containing products. In fact, nicotine-containing products (e.g., tobacco cigarettes, smokeless tobacco [ST], waterpipe, electronic cigarettes [ECIGs], and nicotine replacement [NR] products) have very different characteristics both in terms of sensory and behavioral involvement and also in pharmacokinetic and pharmacodynamic effects. For example, a cigarette and a nicotine patch are very different on almost every one of these dimensions. When ability to stop using a nicotine/tobacco product is used as a criterion for dependence, success rates vary considerably across products: Tobacco cigarette cessation is more difficult than ST cessation that in turn is more difficult than NR product cessation. Based on these results, we hypothesize that there is a continuum of dependence as much as there is a continuum of harm, with tobacco cigarettes and NR products on opposite ends of both continua and other products (waterpipe and ECIGs) somewhere in between. In order to capture more precisely the dependence produced by both nicotine and its administration forms, product-specific instruments may be required. The pros and cons of this approach are discussed.

Background and Aims: The province of Ontario, Canada, banned the use of menthol-flavored tobacco products as of January 1, 2017. This study aims to assess the longer-term impact of a menthol ban on smoking behavior at 2 years, which is unknown.Methods: Population cohort study with baseline survey (n = 1821) conducted September-December 2016 and follow-up survey January-August 2019 among current smokers in Ontario (16+) prior to the menthol ban. Poisson regression was used to assess the probability of quitting smoking by pre-ban menthol status, controlling for differences in smoking and demographic characteristics, with multiple imputations used to address missing data.Findings: Menthol smokers were more likely to report having quit smoking (12% [daily menthol] and 10% [occasional menthol] vs. 3% [non-menthol]; p < .001) than non-menthol smokers in the 2 years after a menthol ban. After adjustment for smoking and demographic characteristics, daily menthol smokers had higher likelihood of quitting smoking (adjusted relative risk [ARR] 2.08; 95% confidence interval [CI] 1.20-3.61) and reported more quit attempts (ARR 1.45; 95% CI 1.15-1.82). Among those who attempted to quit, menthol smoking was not associated with relapse (daily ARR = 0.96; 95% CI: 0.86, 1.07; occasional ARR = 0.99; 95% CI: 0.90, 1.08). However, there was a statistically significant interaction among menthol users who reported using other flavored tobacco products 1 year after the ban (ARR = 0.26 [95% CI: 0.08, 0.90]).Conclusions: The study found increased probability of quitting among daily menthol smokers and more quit attempts among daily and occasional menthol smokers compared with non-menthol smokers in Ontario 2 years after the implementation of a menthol ban.Implications: This study examines quitting behavior 2 years after a menthol ban in Ontario, Canada. Those who were daily menthol smokers prior to the ban were more likely to quit smoking and make more quit attempts in the 2 years after the ban. While there was no difference in the likelihood of relapse between menthol and non-menthol smokers among those who attempt to quit, there were indications that pre-ban daily menthol smokers who used other tobacco products after the ban were likely to quit. [ABSTRACT FROM AUTHOR]