Current and future trends in electronic cigarette use

New tobacco and nicotine products in Latin America and the Caribbean: assessing the market and regulatory environment

OBJECTIVE

To document the regulatory environment of new tobacco and nicotine products (NTNPs), including electronic nicotine delivery systems (ENDS) and heated tobacco products (HTPs), in Latin America and the Caribbean (LAC).

METHODS

Review of market research reports and databases, regulatory websites, Campaign for Tobacco-Free Kids, relevant published literature and the 2021 WHO Report on the Global Tobacco Epidemic.

RESULTS

ENDS entered the LAC market in the 2010s and are now available in most LAC countries. A majority of LAC countries (n=18) have either banned the commercialisation of ENDS (n=7) or regulated ENDS as tobacco products (n=7), medicinal products (n=1) or consumer products (n=3). The remaining LAC countries (n=15) do not regulate ENDS. HTPs were first introduced in 2017 and have been officially launched in five countries (Colombia, Guatemala, Dominican Republic, Mexico and Costa Rica). Few countries have banned HTP commercialisation (n=3) or regulated commercialisation and use (n=7), while the majority of countries have existing legislation that applies to HTPs (n=19). A few countries (n=4) have no tobacco control legislation and therefore do not regulate HTPs.

CONCLUSION

NTNPs are emerging products in the LAC region. Governments should follow WHO guidance and the decisions of the Conference of Parties to the WHO Framework Convention on Tobacco Control and ban or regulate NTNPs as tobacco products; otherwise NTNPs could create a new generation of tobacco and nicotine users.

Regional comparison of self-reported late pregnancy cigarette smoking to mass spectrometry analysis

OBJECTIVE

To report a more accurate prevalence estimate of late pregnancy nicotine exposures.

STUDY DESIGN

A cross-sectional study during a 2-month period in 2019. Participants were women delivering in any of the six county maternity hospitals who consented to universal drug testing at the time of delivery as part of routine hospital admission.

RESULTS

Of 2531 tested samples, 18.7% tested positive for high levels of cotinine indicating primary smoking or other primary use of tobacco products. Together, 33.0% of the study population tested positive for nicotine exposure during late pregnancy compared to vital records which reported 8.2% cigarette smoking during the third trimester of pregnancy and 10.5% cigarette smoking at any time during pregnancy through maternal self-report.

CONCLUSION

Captured vital birth smoking measures vastly underreport actual primary exposures to nicotine products. Vital birth data also fail to capture secondhand exposures which constitute a significant proportion of the population.

Trends in electronic cigarette use and conventional smoking: quantifying a possible 'diversion' effect among US adolescents

BACKGROUND AND AIMS

The impact of electronic cigarettes (ECs) on nicotine use is hotly debated: some fear that ECs are a 'catalyst' to conventional smoking, while others argue that they divert adolescents from the more harmful product. This study used simulation modeling to evaluate the plausibility of catalyst and diversion hypotheses against real-world data.

DESIGN

A simulation model represented life-time exclusive EC use, exclusive conventional smoking and dual use as separate subpopulations. The 'catalyst' effect was modeled as EC use increasing dual use initiation (i.e. EC users also start smoking). The 'diversion' effect was modeled as EC use decreasing exclusive cigarette initiation. The model was calibrated using data from the US National Youth Tobacco Survey (NYTS). The plausibility of each scenario was evaluated by comparing simulated trends with NYTS data. This is the first study, to our knowledge, to estimate the magnitude of a diversion effect through simulation.

SETTING

United States.

PARTICIPANTS AND MEASUREMENTS

Adolescents aged 12-17 years in NYTS, a cross-sectional study from 2000 to 2019 (n = 12 500 to 31 000 per wave). Exclusive cigarette use, exclusive EC use and dual use of both products were defined using cumulative life-time criteria (100+ cigarettes smoked and/or > 100 days vaped).

FINDINGS

A null model (no catalyst or diversion) over-predicts NYTS smoking by up to 87%. Under the conservative assumption that the catalyst effect accounts for all dual use, an exponential decay constant of 19.6% EC users/year initiating smoking is required; however, this further over-predicts actual smoking by up to 109%. A diversion effect with an exponential decay constant of 55.4%/year or 65.4%/year, with the maximum possible opposing catalyst effect also active, is required optimally to match NYTS smoking trends (root mean square error = 286 632 versus 391 396 in the null model).

CONCLUSIONS

A simulation model shows that a substantial diversion effect is needed to explain observed nicotine use trends among US adolescents, and it must be larger than any possible opposing catalyst effect, if present.

Reducing the smoking-related health burden in the USA through diversion to electronic cigarettes: a system dynamics simulation study

BACKGROUND

Electronic cigarettes ("e-cigarettes") have altered tobacco smoking trends, and their impacts are controversial. Given their lower risk relative to combustible tobacco, e-cigarettes have potential for harm reduction. This study presents a simulation-based analysis of an e-cigarette harm reduction policy set in the USA.

METHODS

A system dynamics simulation model was constructed, with separate aging chains representing people in different stages of use (both of combustible cigarettes and e-cigarettes). These structures interact with a policy module to close the gap between actual (simulated) and goal numbers of individuals who smoke, chosen to reduce the tobacco-attributable death rate (i.e., mostly combustible cigarette-attributable, but conservatively allowing e-cigarette-attributable deaths) to that due to all accidents in the general population. The policy is two-fold, removing existing e-liquid flavor bans and providing an informational campaign promoting e-cigarettes as a lower-risk alternative. Realistic practical implementation challenges are modeled in the policy sector, including time delays, political resistance, and budgetary limitations. Effects of e-cigarettes on tobacco smoking occur through three mechanisms: (1) diversion from ever initiating smoking; (2) reducing progression to established smoking; and (3) increasing smoking cessation. An important unintended effect of possible death from e-cigarettes was conservatively included.

RESULTS

The base-case model replicated the historical exponential decline in smoking and the exponential increase in e-cigarette use since 2010. Simulations suggest tobacco smoking could be reduced to the goal level approximately 40 years after implementation. Implementation obstacles (time delays, political resistance, and budgetary constraints) could delay and weaken the effect of the policy by up to 62% in the worst case, relative to the ideal-case scenario; however, these discrepancies substantially decreased over time in dampened oscillations as negative feedback loops stabilize the system after the one-time "shock" introduced by policy changes.

CONCLUSIONS

The simulation suggests that the promotion of e-cigarettes as a harm-reduction policy is a viable strategy, given current evidence that e-cigarettes offset or divert from smoking. Given the strong effects of implementation challenges on policy effectiveness in the short term, accurately modeling such obstacles can usefully inform policy design. Ongoing research is needed, given continuing changes in e-cigarette use prevalence, new policies being enacted for e-cigarettes, and emerging evidence for substitution effects between combustible cigarettes and e-cigarettes.

Electronic Cigarettes Induce Mitochondrial DNA Damage and Trigger TLR9 (Toll-Like Receptor 9)-Mediated Atherosclerosis

OBJECTIVE

Electronic cigarette (e-cig) use has recently been implicated in promoting atherosclerosis. In this study, we aimed to investigate the mechanism of e-cig exposure accelerated atherosclerotic lesion development. Approach and Results: Eight-week-old ApoE^-/- mice fed normal laboratory diet were exposed to e-cig vapor (ECV) for 2 hours/day, 5 days/week for 16 weeks. We found that ECV exposure significantly induced atherosclerotic lesions as examined by Oil Red O staining and greatly upregulated TLR9 (toll-like receptor 9) expression in classical monocytes and in the atherosclerotic plaques, which the latter was corroborated by enhanced TLR9 expression in human femoral artery atherosclerotic plaques from e-cig smokers. Intriguingly, we found a significant increase of oxidative mitochondria DNA lesion in the plasma of ECV-exposed mice. Administration of TLR9 antagonist before ECV exposure not only alleviated atherosclerosis and the upregulation of TLR9 in plaques but also attenuated the increase of plasma levels of inflammatory cytokines, reduced the plaque accumulation of lipid and macrophages, and decreased the frequency of blood CCR2⁺ (C-C chemokine receptor type 2) classical monocytes. Surprisingly, we found that cytoplasmic mitochondrial DNA isolated from ECV extract-treated macrophages can enhance TLR9 activation in reporter cells and the induction of inflammatory cytokine could be suppressed by TLR9 inhibitor in macrophages.

CONCLUSIONS

E-cig increases level of damaged mitochondrial DNA in circulating blood and induces the expression of TLR9, which elevate the expression of proinflammatory cytokines in monocyte/macrophage and consequently lead to atherosclerosis. Our results raise the possibility that intervention of TLR9 activation is a potential pharmacological target of ECV-related inflammation and cardiovascular diseases.

Electronic cigarettes, nicotine use trends and use initiation ages among US adolescents from 1999 to 2018

BACKGROUND AND AIMS

Recent nicotine use trends raise concerns that electronic cigarettes (ECs) may act as a gateway to cigarettes among adolescents. The aims of this study were to examine prevalence trends of exclusive EC use, exclusive cigarette use and dual use to determine the corresponding ages of initiation and to investigate hypothetical trends in total nicotine use and cigarette use in the absence of ECs among US adolescents.

DESIGN

Observational study using data from the National Youth Tobacco Survey (NYTS) to statistically model trends in the prevalences of each user group and their initiation ages. Projections from counterfactual models based on data from 1999 to 2009 (before EC introduction) were compared with actual trends based on data from 1999 to 2018. Rigorous error analyses were applied, including Theil proportions.

SETTING

USA.

PARTICIPANTS AND MEASUREMENTS

Adolescents aged 12-17 years who were established exclusive cigarette users (≥ 100 cigarettes smoked and ≤ 100 days vaped), established exclusive EC users (< 100 cigarettes smoked and > 100 days vaped) and established dual users (≥ 100 cigarettes smoked and > 100 days vaped), based on cumulative life-time exposure (n ≈ 12 500-31 000 per wave).

FINDINGS

Exclusive cigarette use prevalence declined from 1999 to 2018, while exclusive EC use and dual use prevalences increased since their introduction in 2009. The age of cigarette initiation began a slight increase after 2014, whereas the age for EC use remained approximately constant and was higher than that of cigarettes. The counterfactual comparison results were consistent with ECs not increasing the number of US adolescent nicotine users, and in fact diverting adolescents from cigarettes.

CONCLUSIONS

Electronic cigarettes may have offset conventional smoking among US adolescents between 2010 and 2018 by maintaining the total nicotine use prevalence and diverting them from more harmful conventional smoking. Additionally, electronic cigarette users appear to initiate at older ages relative to conventional smokers, which is associated with lower risk.

Legislation Related to E-Cigarettes in The Gulf Cooperation Council Countries

Even though 90% of the world’s population is covered by the World Health Organization’s Framework Convention on Tobacco Control, it is estimated that only one-fifth (21%) and half (49%) of the countries that ratified this convention will achieve the target of reducing tobacco use by 30 % among men and women respectively in 2025. Over the past decade, there has been an increasing trend in the use of electronic cigarettes or e-cigarettes for recreational use as well as smoking cessation. In concurrence with the increasing use of e-cigarettes among smokers of different age groups, nations have developed relevant national regulations on its sale, advertisement, packaging, product regulation, taxation, and surveillance. The countries of the Gulf Cooperation Council (GCC) region have also witnessed several legislations, at varying extent, related to the use of electronic cigarettes. However, the evidence on the use of electronic nicotine delivery systems remains scarce in the GCC region. Thus, further research on this emerging public health issue is warranted to generate the evidence necessary for the formulation of comprehensive tobacco control laws and effective prevention strategies.

The Relationship Between Electronic Cigarette Use and Conventional Cigarette Smoking Is Largely Attributable to Shared Risk Factors

INTRODUCTION

The growing popularity of electronic cigarettes (e-cigarettes) among youth raises concerns about possible causal effects on conventional cigarette smoking. However, past research remains inconclusive due to heavy confounding between cigarette and e-cigarette use. This study uses propensity score methods to robustly adjust for shared risk in estimating the relationship between e-cigarette use and conventional smoking.

METHODS

Cross-sectional data from 8th and 10th graders were drawn from the 2015-2016 waves of Monitoring the Future (n = 12 421). The effects of (1) lifetime and (2) current e-cigarette use on (A) lifetime and (B) current conventional cigarette smoking were examined using logistic regression analyses with inverse propensity weighting based on 14 associated risk factors.

RESULTS

After accounting for the propensity for using e-cigarettes based on 14 risk factors, both lifetime and current e-cigarette use significantly increased the risk of ever smoking a conventional cigarette (OR = 2.49, 95% CI = 1.77 to 3.51; OR = 2.32, 95% CI = 1.66 to 3.25, respectively). However, lifetime (OR = 2.17, 95% CI = 0.62 to 7.63) and current e-cigarette use (OR = 0.95, 95% CI = 0.55 to 1.63) did not significantly increase the risk of current conventional cigarette smoking.

CONCLUSIONS

E-cigarette use does not appear to be associated with current, continued smoking. Instead, the apparent relationship between e-cigarette use and current conventional smoking is fully explained by shared risk factors, thus failing to support claims that e-cigarettes have a causal effect on concurrent conventional smoking among youth. E-cigarette use has a remaining association with lifetime cigarette smoking after propensity score adjustment; however, future research is needed to determine whether this is a causal relationship or merely reflects unmeasured confounding.

IMPLICATIONS

This study examines the relationship between e-cigarette use and conventional smoking using inverse propensity score weighting, an innovative statistical method that produces less-biased results in the presence of heavy confounding. Our findings show that the apparent relationship between e-cigarette use and current cigarette smoking is entirely attributable to shared risk factors for tobacco use. However, e-cigarette use is associated with lifetime cigarette smoking, though further research is needed to determine whether this is a causal relationship or merely reflects unaccounted-for confounding. Propensity score weighting produced significantly weaker effect estimations compared to conventional regression control.

Nicotine and Carbonyl Emissions From Popular Electronic Cigarette Products: Correlation to Liquid Composition and Design Characteristics

Introduction

Available in hundreds of device designs and thousands of flavors, electronic cigarette (ECIG) may have differing toxicant emission characteristics. This study assesses nicotine and carbonyl yields in the most popular brands in the U.S. market. These products included disposable, prefilled cartridge, and tank-based ECIGs.

Methods

Twenty-seven ECIG products of 10 brands were procured and their power outputs were measured. The e-liquids were characterized for pH, nicotine concentration, propylene glycol/vegetable glycerin (PG/VG) ratio, and water content. Aerosols were generated using a puffing machine and nicotine and carbonyls were, respectively, quantified using gas chromatograph and high-performance liquid chromatography. A multiregression model was used to interpret the data.

Results

Nicotine yields varied from 0.27 to 2.91 mg/15 puffs, a range corresponding to the nicotine yield of less than 1 to more than 3 combustible cigarettes. Nicotine yield was highly correlated with ECIG type and brand, liquid nicotine concentration, and PG/VG ratio, and to a lower significance with electrical power, but not with pH and water content. Carbonyls, including the carcinogen formaldehyde, were detected in all ECIG aerosols, with total carbonyl concentrations ranging from 3.72 to 48.85 µg/15 puffs. Unlike nicotine, carbonyl concentrations were mainly correlated with power.

Conclusion

In 15 puffs, some ECIG devices emit nicotine quantities that exceed those of tobacco cigarettes. Nicotine emissions vary widely across products but carbonyl emissions showed little variations. In spite of that ECIG users are exposed to toxicologically significant levels of carbonyl compounds, especially formaldehyde. Regression analysis showed the importance of design and e-liquid characteristics as determinants of nicotine and carbonyl emissions.

Implications

Periodic surveying of characteristics of ECIG products available in the marketplace is valuable for understanding population-wide changes in ECIG use patterns over time.

Does E-cigarette Use at Baseline Influence Smoking Cessation Rates among 2-Year College Students?

INTRODUCTION

This study evaluates the impact of baseline e-cigarette use on smoking cessation rates in a national sample of two-year college student smokers.

METHODS

Participants were 1400 students from over 60 two-year colleges across 25 states who were current smokers enrolled in a web-assisted tobacco intervention (WATI) trial. Survey data were collected at baseline, 1-, 6-, and 12-months, with primary outcomes evaluated at 6-months.

RESULTS

At 6-months, baseline e-cigarette users were more likely to report cessation of traditional cigarettes compared to non-users (OR 1.39, 95% CI 1.002-1.92). Cessation was also associated with higher baseline confidence in quitting and greater time to first cigarette in the morning. Baseline e-cigarette use was not found to be associated with self-reported cessation of all nicotine/tobacco products (OR 1.09, 95% CI 0.75-1.58) nor biochemically verified cessation of all nicotine/tobacco products (OR 0.83, 95% CI 0.47-1.47). Higher confidence was again associated with both self-reported and biochemically verified cessation of all nicotine/tobacco products. Female gender was associated only with biochemically verified cessation of all nicotine/tobacco products at 6-months.

CONCLUSIONS

Two-year college students represent a priority population for cessation interventions. The findings from this study highlight the complexities of evaluating the impact of e-cigarette use on cessation.

Evaluating the mutual pathways among electronic cigarette use, conventional smoking and nicotine dependence

BACKGROUND AND AIMS

The implications of the rapid rise in electronic cigarette (e-cigarette) use remain unknown. We examined mutual associations between e-cigarette use, conventional cigarette use and nicotine dependence over time to (1) test the association between e-cigarette use and later conventional smoking (both direct and via nicotine dependence), (2) test the converse associations and (3) determine the strongest pathways predicting each product's use.

DESIGN

Data from four annual waves of a prospective cohort study were analyzed. Path analysis modeled the bidirectional, longitudinal relationships between past-month smoking frequency, past-month e-cigarette frequency and nicotine dependence.

SETTING

Chicago area, Illinois, USA.

PARTICIPANTS

A total of 1007 young adult smokers and non-smokers (ages 19-23 years).

MEASUREMENTS

Frequency of (1) cigarettes and (2) e-cigarettes was the number of days in the past 30 on which the product was used. The Nicotine Dependence Syndrome Scale measured nicotine dependence to cigarettes.

FINDINGS

E-cigarette use was not associated significantly with later conventional smoking, either directly (β = 0.021, P = 0.081) or through nicotine dependence (β = 0.005, P = 0.693). Conventional smoking was associated positively with later e-cigarette use, both directly (β = 0.118, P < 0.001) and through nicotine dependence (β = 0.139, P < 0.001). The strongest predictors of each product's use was prior use of the same product; this pathway was strong for conventional cigarettes (β = 0.604, P < 0.001) but weak for e-cigarettes (β = 0.120, P < 0.001). Nicotine dependence moderately strongly predicted later conventional smoking (β = 0.169, P < 0.001), but was a weak predictor of later e-cigarette use (β = 0.069, P = 0.039).

CONCLUSIONS

Nicotine dependence is not a significant mechanism for e-cigarettes' purported effect on heavier future conventional smoking among young adults. Nicotine dependence may be a mechanism for increases in e-cigarette use among heavier conventional smokers, consistent with e-cigarettes as a smoking reduction tool. Overall, conventional smoking and, to a lesser extent, its resulting nicotine dependence, are the strongest drivers or signals of later cigarette and e-cigarette use.

Impaired Lung Mitochondrial Respiration Following Perinatal Nicotine Exposure in Rats

Perinatal smoke/nicotine exposure predisposes to chronic lung disease and morbidity. Mitochondrial abnormalities may contribute as the PPARγ pathway is involved in structural and functional airway deficits after perinatal nicotine exposure. We hypothesized perinatal nicotine exposure results in lung mitochondrial dysfunction that can be rescued by rosiglitazone (RGZ; PPARγ receptor agonist). Sprague-Dawley dams received placebo (CON), nicotine (NIC, 1 mg kg(-1)), or NIC + RGZ (3 mg kg(-1)) daily from embryonic day 6 to postnatal day 21. Parenchymal lung (~10 mg) was taken from adult male offspring for mitochondrial assessment in situ. ADP-stimulated O2 consumption was less in NIC and NIC + RGZ compared to CON (F[2,14] = 17.8; 4.5 ± 0.8 and 4.1 ± 1.4 vs. 8.8 ± 2.5 pmol s mg(-1); p < 0.05). The respiratory control ratio for ADP, an index of mitochondrial coupling, was reduced in NIC and remediated in NIC + RGZ (F[2,14] = 3.8; p < 0.05). Reduced mitochondrial oxidative capacity and abnormal coupling were evident after perinatal nicotine exposure. RGZ improved mitochondrial function through tighter coupling of oxidative phosphorylation.