The effect of e-cigarette aerosol emissions on respiratory health: a narrative review

Dental plaque quantitation by light induced fluorescence technology in exclusive Electronic Nicotine Delivery Systems (ENDS) users

OBJECTIVES

In comparison to conventional combustible cigarettes, Electronic Nicotine Delivery Systems (ENDS) including both e-cigarettes (ECs) and heated tobacco products (HTPs) significantly reduce exposure to toxic chemical emissions. However, their impact on dental plaque remains unclear. This study measures dental plaque in ENDS (ECs and HTPs) users using quantitative light-induced fluorescence (QLF) technology, comparing them with current, former, and never smokers.

METHODS

This cross-sectional study compared dental plaque measurements using QLF technology (Q-ray cam™ Pro) among current smokers (≥10 cigarettes/day), former smokers (quit ≥6 months), never smokers, and exclusive ENDS users (quit ≥6 months). Dental plaque measurements were expressed as ΔR30 (total area of mature dental plaque) and ΔR120 (greater plaque thickness/maturation-calculus). The Simple Oral Hygiene (SOH) score was calculated by the QLF proprietary software. Statistical analyses including ANCOVA was performed by R version (4.2.3) with p < 0.05.

RESULTS

A total 30 smokers, 24 former smokers, 29 never smokers, and 53 ENDS users were included. Current smokers had significantly higher ΔR30 and ΔR120 values compared to other groups (p < 0.001). ENDS users showed plaque levels similar to never and former smokers (p > 0.05) but significantly lower than current smokers (p < 0.01). Although ENDS users showed a lower SOH score than smokers, this difference was not statistically significant. Daily toothbrushing and mouthwash usage were significant covariates.

CONCLUSION

ENDS users exhibited reduced accumulation of dental plaque and calculus compared with current smokers.

CLINICAL SIGNIFICANCE

Exclusive ENDS use could less impact dental plaque accumulation compared to cigarette smoking. Further research is needed to confirm these findings and fully understand ENDS impact on dental plaque formation.

Document analysis of the Foundation for a Smoke-Free World's scientific outputs and activities: a case study in contemporary tobacco industry agnogenesis

BACKGROUND

Tobacco corporation Philip Morris International launched the Foundation for a Smoke-Free World (FSFW), a purportedly independent scientific organisation, in 2017. We aimed to systematically investigate FSFW's activities and outputs, comparing these with previous industry attempts to influence science, as identified in the recently developed typology of corporate influence on science, the Science for Profit Model (SPM).

DESIGN

We prospectively collected data on FSFW over a 4-year period, 2017-2021, and used document analysis to assess whether FSFW's activities mirror practices tobacco and other industries have historically used to shape science in their own interests. We used the SPM as an analytical framework, working deductively to search for use of the strategies it identifies, and inductively to search for any additional strategies.

RESULTS

Marked similarities between FSFW's practices and previous corporate attempts to influence science were observed, including: producing tobacco industry-friendly research and opinion; obscuring industry involvement in science; funding third parties which denigrate science and scientists that may threaten industry profitability; and promoting tobacco industry credibility.

CONCLUSIONS

Our paper identifies FSFW as a new vehicle for agnogenesis, indicating that, over 70 years since the tobacco industry began to manipulate science, efforts to protect science from its interference remain inadequate. This, combined with growing evidence that other industries are engaging in similar practices, illustrates the urgent need to develop more robust systems to protect scientific integrity.

Development of a Flavor Ingredient Wheel Linking E-Liquid Additives to the Labeled Flavor of Vaping Products

E-liquids contain combinations of chemicals, with many enhancing the sensory attractiveness of the product. Studies are needed to understand and characterize e-liquid ingredients, particularly flavorings, to inform future research and regulations of these products. We identified common flavor ingredients in a convenience sample of commercial e-liquids using gas chromatography-mass spectrometry. E-liquid flavors were categorized by flavor descriptors provided on the product packaging. A Flavor Ingredient Wheel was developed to link e-liquid flavor ingredients with flavor categories. An analysis of 109 samples identified 48 flavor ingredients. Consistency between the labeled flavor and ingredients used to produce such flavor was found. Our novel Flavor Ingredient Wheel organizes e-liquids by flavor and ingredients, enabling efficient analysis of the link between ingredients and their flavor profiles and allowing for quick assessment of an e-liquid ingredient's flavor profile. Investigating ingredient profiles and identifying and classifying commonly used chemicals in e-liquids may assist with future studies and improve the ability to regulate these products.

A Global Health Survey of People Who Vape but Never Smoked: Protocol for the VERITAS (Vaping Effects: Real-World International Surveillance) Study

BACKGROUND

There is only limited information about the health effects of regular vaping. Research on the health status of people who used to smoke faces the challenge that previous smoking may have caused unknown health effects. Only studies of people who vape but have never smoked combustible cigarettes can enable the detection of harms attributable to vaping. Large prospective studies of well-characterized electronic cigarette users with and without a history of combustible cigarette smoking are warranted to establish the long-term effects of regular vaping on respiratory health.

OBJECTIVE

We will conduct a global cross-sectional survey of individuals from 6 world regions. Respiratory symptoms will be assessed using a validated questionnaire-the Respiratory Symptom Experience Scale (RSES). Current vapers who are nonusers of other tobacco or nicotine products will be compared with matched controls who are nonusers of vapes and other tobacco or nicotine products.

METHODS

This will be a multicountry, cross-sectional internet-based survey of 750 adults aged ≥18 years who satisfy the criteria for inclusion in either a cohort of people who exclusively vape and who are nonusers of other tobacco or nicotine products ("vapers cohort"; target N=500) or a cohort of nonvapers who are also nonusers of other tobacco or nicotine products ("controls cohort"; target N=250). The primary end point of the study is the RSES score. RSES scores of people in the "vapers cohort" will be compared with those of people in the "controls cohort." Additionally, the study will collect data to characterize patterns of vaping product use among the vapers cohort. Data collection will include information about the age initiation of using vape products, reasons for starting and continuing the use of vape products, specific types of products used, flavors and nicotine strengths of recently used products, as well as the frequency and intensity of product use in the past 30 days.

RESULTS

Participant recruitment started in April 2023, and enrollment was completed by November 2023 with 748 participants. Results will be reported in 2024.

CONCLUSIONS

This will be the first study providing key insights into respiratory health effects associated with using electronic cigarettes in people who vape with no established use of combustible cigarettes or other tobacco or nicotine products.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/54236.

The potential health effects associated with electronic-cigarette

A good old gateway theory that electronic-cigarettes (e-cigarettes) are widely recognized as safer tobacco substitutes. In actuality, demographics also show that vaping cannibalizes smoking, the best explanation of the data is the "common liability". However, the utilization of e-cigarette products remains a controversial topic at present. Currently, there has been a widespread and substantial growth in e-cigarette use worldwide owing to their endless new flavors and customizable characteristics. Furthermore, e-cigarette has grown widespread among smokers as well as non-smokers, including adolescents and young adults. And some studies have shown that e-cigarette users are at greater risk to start using combustible cigarettes while e-cigarettes use was also observed the potential benefits to people who want to quit smoking or not. Although it is true that e-cigarettes generally contain fewer toxic substances than combustible cigarettes, this does not mean that the chemical composition in e-cigarettes aerosols poses absolutely no risks. While concerns about toxic substances in e-cigarettes and their widespread use in the population are reasonable, it is also crucial to consider that e-cigarettes have been associated with the potential for promoting smoking cessation and the clinically relevant improvements in users with smoking-related pathologies. Meanwhile, there is still short of understanding of the health impacts associated with e-cigarette use. Therefore, in this review, we discussed the health impacts of e-cigarette exposure on oral, nasal, pulmonary, cardiovascular systems and brain. We aspire for this review to change people's previous perceptions of e-cigarettes and provide them with a more balanced perspective. Additionally, we suggest appropriate adjustments on regulation and policy for e-cigarette to gain greater public health benefits.

A multicenter prospective randomized controlled trial investigating the effects of combustion-free nicotine alternatives on cardiovascular risk factors and metabolic parameters in individuals with type 2 diabetes who smoke: the DiaSmokeFree study protocol

Stopping smoking is crucial for public health and especially for individuals with diabetes. Combustion-free nicotine alternatives like e-cigarettes and heated tobacco products are increasingly being used as substitutes for conventional cigarettes, contributing to the decline in smoking prevalence. However, there is limited information about the long-term health impact of those products in patients with diabetes. This randomized controlled trial aims to investigate whether switching from conventional cigarettes to combustion-free nicotine alternatives will lead to a measurable improvement in cardiovascular risk factors and metabolic parameters over a period of 2 years in smokers with type 2 diabetes. The multicenter study will be conducted in seven sites across four countries. A total of 576 smokers with type 2 diabetes will be randomly assigned (1:2 ratio) to either standard of care with brief cessation advice (Control Arm) or combustion-free nicotine alternatives use (Intervention Arm). The primary end point is the change in the proportion of patients with metabolic syndrome between baseline and the 2-year follow-up. Additionally, the study will analyze the absolute change in the sum of the individual factors of metabolic syndrome at each study time point. Patient recruitment has started in September 2021 and enrollment is expected to be completed by December 2023. Results will be reported in 2026. This study may provide valuable insights into cardiovascular and metabolic health benefits or risks associated with using combustion-free nicotine alternatives for individuals with type 2 diabetes who are seeking alternatives to tobacco cigarette smoking. The study protocol, informed consent forms, and relevant documents were approved by seven ethical review boards. Study results will be disseminated through articles published in high-quality, peer-reviewed journals and presentations at conferences.

E-cigarettes and heated tobacco products impact on dental color parameters

Objectives

Abstaining from tobacco smoking may not only improve general health, but also reduce teeth staining and restore teeth whiteness. Compared with conventional cigarettes, E-cigarettes (ECs) and heated tobacco products (HTPs) may offer substantial reduction in exposure to pigmented tar-like compounds of cigarette smoke. It is possible that improvements in dental color indices may be observed in those who have stopped smoking combustible cigarettes by switching to tar-free nicotine delivery products.

Methods

This cross-sectional study evaluated and compared dental color parameters by digital spectrophotometry among five different groups: individuals who currently smoke ; individuals who used to smoke but have quit ; individuals who have never smoked ; exclusive users of electronic cigarettes (former smokers) ; and exclusive users of heated tobacco products (former smokers) .

Results

Dental whiteness in current cigarette smokers was notably worse compared with never and former smokers, (13.38 Whiteness Index for Dentistry (WID) units vs. 19.96 and 16.79 WID units). Remarkably high WID values (i.e., whiter teeth) were also observed in ECs (16.72 WID units) and HTPs users (17.82 WID units). Compared to current smokers, difference in dental whiteness for ECs and HTPs users was visually noticeable (ΔWID difference being on average > 2.90 units). The colour differences measured as delta E*(ΔE*) were all visually detectable except for the comparison between ex-smokers and ECs users for which no perceptible color difference was observed (0.415).

Conclusion

Exclusive use of ECs and HTPs is associated with better dental color measurements than current smoking, suggesting that tar-free nicotine delivery technologies are unlikely to have negative effects on dental appearance.

Clinical significance

Use of alternative nicotine delivery systems may be associated with cosmetic benefits with important implications for those smokers perceiving dental aesthetics as a significant problem. For these an oral-based narrative may be a much more significant reason to refrain from smoking than the fear of developing smoking-related diseases in future.

Comparative assessment of electronic nicotine delivery systems aerosol and cigarette smoke on endothelial cell migration: The Replica Project

Cigarette smoking is associated with impairment of repair mechanisms necessary for vascular endothelium homeostasis. Reducing the exposure to smoke toxicants may result in the mitigation of the harmful effect on the endothelium and cardiovascular disease development. Previous investigations evaluated in vitro the effect of electronic cigarette (EC) compared with cigarette smoke demonstrating a significant reduction in human umbilical vein endothelial cells (HUVECs) migration inhibition following EC aerosol exposure. In the present study, we replicated one of these studies, evaluating the effects of cigarette smoke on endothelial cell migration compared with aerosol from EC and heated tobacco products (HTPs). We performed an in vitro scratch wound assay on endothelial cells with a multi-center approach (ring-study) to verify the robustness and reliability of the results obtained in the replicated study, also testing the effect of aerosol from two HTPs on endothelial cells. Consistently with the original study, we observed a substantial reduction of the effects of aerosol from EC and HTPs on endothelial cell migration compared with cigarette smoke. While cigarette smoke reduced endothelial wound healing ability already at low concentrations (12.5%) and in a concentration-dependent manner, EC and HTPs aerosol showed no effect on endothelial cells until 80%-100% concentrations. In conclusion, our study further confirms the importance of EC and tobacco heated products as a possible harm reduction strategy for cardiovascular diseases development in smokers.

In vitro cytoxicity profile of e-cigarette liquid samples on primary human bronchial epithelial cells

Cigarette smoke is associated to severe chronic diseases. The most harmful components of cigarette smoke derive from the combustion process, which are significantly reduced in the electronic cigarette aerosol, thus providing a valid option in harm reduction strategies. To develop safer products, it is therefore necessary to screen electronic cigarette liquids (e-liquids) to meet high safety standards defined by government regulations. The aim of the present study was to evaluate the presence of metal- and plastic-derived contaminants in four different commercial e-liquids with high concentration of nicotine and their cytotoxic effect in normal human bronchial epithelial cells by a number of in vitro assays, in comparison with the 1R6F reference cigarette, using an air-liquid interface (ALI) exposure system. Moreover, we evaluated the effect of aerosol exposure on oxidative stress by measuring the production of reactive oxygen species and mitochondrial potential. Our results showed no contaminants in all e-liquids and a significantly reduced cytotoxic effect of e-liquid aerosol compared to cigarette smoke as well as a maintained mitochondria integrity. Moreover, no production of reactive oxygen species was detected with e-cigarette aerosol. In conclusion, these results support the reduced toxicity potential of e-cigs compared to tobacco cigarettes in an in vitro model resembling real life smoke exposure.

Varenicline and counseling for vaping cessation: a double-blind, randomized, parallel-group, placebo-controlled trial

BACKGROUND

Vaping cessation is virtually unexplored. The efficacy and safety of varenicline for vaping cessation has not been studied and rigorous research is required to advance best practice and outcomes for people who use electronic cigarettes (EC) and want to quit. The objective is to evaluate the efficacy and safety of varenicline (1 mg BID, administered for 12 weeks, with follow-up to week 24) combined with vaping cessation counseling in exclusive daily EC users intending to quit vaping.

METHODS

Design: Double-blind, randomized, parallel-group, placebo-controlled trial.

SETTING

The study took place at a University-run smoking cessation center.

PARTICIPANTS

People who exclusively use ECs daily and intend to quit vaping.

INTERVENTION

A total of 140 subjects were randomized to either varenicline (1 mg, administered twice daily for 12 weeks) plus counseling or placebo treatment (administered twice daily, for 12 weeks) plus counseling. The trial consisted of a 12-week treatment phase followed by a 12-week follow-up, nontreatment phase.

MAIN OUTCOMES AND MEASURES

The primary efficacy endpoint of the study was biochemically validated continuous abstinence rate (CAR) at weeks 4 to 12. Secondary efficacy end points were CAR at weeks 4 to 24 and 7-day point prevalence of vaping abstinence at weeks 12 and 24.

RESULTS

CAR was significantly higher for varenicline vs placebo at each interval: weeks 4-12, 40.0% and 20.0%, respectively (OR = 2.67, 95% CI = [1.25-5.68], P = 0.011); weeks 4-24, 34.3% for varenicline with counseling and 17.2% for placebo with counseling (OR = 2.52, 95% CI = [1.14-5.58], P = 0.0224). The 7-day point prevalence of vaping abstinence was also higher for the varenicline than placebo at each time point. Serious adverse events were infrequent in both groups and not treatment-related.

CONCLUSIONS

The findings of the present RCT indicate that inclusion of varenicline in a vaping cessation program for people who use electronic cigarettes and intending to quit may result in prolonged abstinence. These positive findings establish a benchmark of intervention effectiveness, may support the use of varenicline combined with counseling in vaping cessation programs, and may also help guiding future recommendations by health authorities and healthcare providers.

TRIAL REGISTRATION

The study has been registered in EUDRACT with Trial registration ID: 2016-000339-42.

A downstream social norms approach for curtailing e-cigarette waste: Promising social marketing interventions from consumer interactions

Irresponsibly disposed electronic cigarette (e-cigarette) waste poses significant public health and environmental harm. This study explores downstream social marketing interventions that can be used to curtail the growth of e-cigarette waste in South Africa through the lenses of the social norms approach. This study harnesses the power of social marketing to identify downstream interventions that can be used by marketers to curb the problem of e-cigarette waste. An exploratory research design and a qualitative method were employed. Six virtual focus groups were conducted to collect cross-sectional data from South African electronic cigarette users. Reciprocal altruism, social orientation value, moral licensing and ecological beliefs were found to be the main normative influences that characterise e-cigarette waste. The results support the proposition that social marketers should employ a downstream approach to develop interventions to curtail the growth of e-cigarette waste. Such measures are envisaged to complement upstream initiatives. This study offers new insights on how to manage e-cigarette waste in the context of an emerging market.

Comparison of the effects of electronic cigarette vapours and tobacco smoke extracts on human neutrophils in vitro

Background

Electronic cigarettes (ECs) are electronic aerosol delivery systems composed of nicotine and various chemicals, which are widely used to facilitate smoking cessation. Although ECs are considered safer than cigarettes, they do, however, contain chemical toxicants, some of which may interact with cells of the host's innate immune system of which neutrophils constitute a key component.

Methods

The current study was designed to compare the effects of aqueous EC aerosol extracts (ECEs; with or without nicotine) with those of cigarette smoke extract (CSE) on neutrophil and platelet reactivity in vitro. Neutrophil reactivity is characterised by the generation of reactive oxygen species (ROS), degranulation (elastase release) and the release of extracellular DNA (neutrophil extracellular trap (NET) formation: NETosis), which were measured using chemiluminescence, spectrophotometric and microscopic procedures, respectively. Platelet reactivity was measured according to the magnitude of upregulated expression of the adhesion molecule CD62P on activated cells using a flow cytometric procedure.

Results

Exposure of neutrophils to either ECEs or CSE caused a significant inhibition of ROS generation and elastase release by N-formyl-l-methionyl-l-leucyl-l-phenylalanine (1 µM)-activated neutrophils. Pre-treatment of neutrophils with CSE also resulted in a marked attenuation of phorbol 12-myristate 13-acetate (6.25 nM)-mediated release of extracellular DNA, which was unaffected by the ECEs. Similarly, CSE, but not the ECEs, inhibited the expression of CD62P by platelets activated with ADP (100 µM).

Conclusions

These observations suggest that ECE aerosols may inhibit some of the immuno-protective activities of neutrophils such as ROS production and elastase release by activated cells, the effect of which was not enhanced by inclusion of nicotine. The inhibitory effects of CSE were significantly more pronounced than those of ECEs, especially so for suppression of NET formation and platelet activation. If operative in vivo, these harmful immunosuppressive effects of ECEs may compromise intrinsic pulmonary antimicrobial defence mechanisms, albeit less so than cigarette smoke.

Nicotine-Free E-Cigarettes Might Promote Tobacco Smoking Reduction Better Than Nicotine Delivery Devices: Results of a Double-Blind Randomized Controlled Trial at 1 Year

The purpose of the present study was to determine whether the use of e-cigarettes to aid in quitting contributed to the increase in the pulmonary health of chronic smokers. The efficacy of e-cigarettes to support a successful smoking cessation attempt was also investigated. A total of 210 smokers (78 women) were enrolled in a screening program for the early detection of lung cancer and distributed in three arms: nicotine e-cigarette plus support, nicotine-free e-cigarette plus support, and support. Results showed that participants in the nicotine e-cigarette arm had a significant and fast decrease in daily cigarettes, but that later they resume smoking more than the other two groups. Conversely, participants in the other two arms showed similar daily consumption at the two evaluation points. Among abstinent participants, only 12.5% reported cough, while 48% of current smokers had pulmonary symptoms. Our study suggests that, in the long run, the use of a nicotine-free liquid may favor reducing smoking and could be considered a good option in a clinical setting.

The Respiratory Symptom Experience Scale (RSES): Quantitative Psychometric Assessment and Validation of a New Questionnaire to Assess Respiratory Symptoms in Current and Former Smokers RSES (Preprint)

BACKGROUND

Smokers often experience respiratory symptoms (eg, morning cough), and those who stop smoking, including those who do so by switching completely to electronic nicotine delivery systems (ENDS), may experience reductions in symptoms. Existing respiratory symptom questionnaires may not be suitable for studying these changes, as they are intended for patient populations, such as those with chronic obstructive pulmonary disease (COPD).

OBJECTIVE

This study aimed to develop a respiratory symptom questionnaire appropriate for current smokers and for assessing changes when smokers stop smoking.

METHODS

The Respiratory Symptom Experience Scale (RSES) was derived from existing instruments and subject matter expert input and refined through cognitive debriefing interviews (n=49). Next, for purposes of the quantitative psychometric evaluation, the RSES was administered to smokers (n=202), former smokers (no tobacco use in >6 months; n=200), and switchers (n=208, smokers who switched to ENDS for >6 months), all of whom had smoked for at least 10 years (mean age 33 years). Participants, who averaged 62 (SD 12) years of age, included 28% (173/610) with respiratory allergy symptoms and 17% (104/610) with COPD. Test-retest reliability was assessed by repeat assessment after 1 week in 128 participants.

RESULTS

A generalized partial credit model confirmed that the response options were ordered, and a parallel analysis using principal components confirmed that the scale was unidimensional. With allowance for 2 sets of correlated errors between pairs of items, a 1-factor graded response model fit the data. Discrimination parameters were approximately 1 or greater for all items. Scale reliability was 0.80 or higher across a broad range of severity (standardized scores -0.40 to 3.00). Test-retest reliability (absolute intraclass correlation) was good, at 0.89. RSES convergent validity was supported by substantial differences (Cohen d=0.74) between those with and without a diagnosis of respiratory disease (averaging 0.57 points, indicating that differences of this size or smaller represent meaningful differences). RSES scores also strongly differentiated those with and without COPD (d=1.52). Smokers' RSES scores were significantly higher than former smokers' scores (P<.001). Switchers' RSES scores were significantly lower than smokers' scores (P<.001) and no different from former smokers' scores (P=.34).

CONCLUSIONS

The RSES fills an important gap in the existing toolkit of respiratory symptom questionnaires; it is a reliable and valid tool to assess respiratory symptoms in adult current and former smokers, including those who have switched to noncombusted nicotine products. This suggests that the scale is sensitive to respiratory symptoms that develop in smokers and to their remission when smokers quit or switch to noncombusted nicotine products intended to reduce the harm of smoking. The findings also suggest that switching from cigarettes to ENDS may improve respiratory health.

A Close Look at Vaping in Adolescents and Young Adults in the United States

Vaping by adolescents and young adults is a legitimate concern as there is a risk that some may start smoking and that electronic cigarette (EC) use may have adverse effects in the developing lungs of adolescents. This commentary provides updated information on vaping patterns among adolescents and young adults in the United States, as well as the impact of EC usage on respiratory health. EC use has surged greatly among high school students and young adults over the last decade but fortunately has declined significantly since its peak in 2019. During the same time period, smoking rates have constantly fallen to new low record levels. These trends argue against EC use as a gateway to smoking. Most EC usage is infrequent and unlikely to increase a person's risk of negative health consequences. Furthermore, the majority of EC usage has happened among those who have previously smoked. There is a dearth of data on the long-term health implications of EC usage in adolescents and young adults. We do not know whether short-term or intermittent use of EC in youth can lead to negative health outcomes in adulthood, and long-term high-quality studies in well-defined groups are needed. Although vaping has been linked to respiratory symptoms, they tend to be transient and of uncertain significance. This commentary provides up-to-date information so health care providers can give objective and responsible medical advice on EC usage.

Health impact of e-cigarettes and heated tobacco products in chronic obstructive pulmonary disease: current and emerging evidence

INTRODUCTION

Quitting is the only proven method to attenuate the progression of chronic obstructive pulmonary disease (COPD). However, most COPD smokers do not seem to respond to smoking cessation interventions and may benefit by lessening the negative health effects of long-term cigarette smoke exposure by switching to non-combustible nicotine delivery alternatives, such as heated tobacco products (HTPs) and e-cigarettes (ECs).

AREAS COVERED

Compared with conventional cigarettes, HTPs and ECs offer substantial reduction in exposure to toxic chemicals and have the potential to reduce harm from cigarette smoke when used as tobacco cigarette substitutes. In this review, we examine the available clinical studies and population surveys on the respiratory health effects of ECs and HTPs in COPD patients.

EXPERT OPINION

The current research on the impact of ECs and HTPs on COPD patients' health is limited, and more high-quality studies are needed to draw definitive conclusions. However, this review provides a comprehensive overview of the available literature for health professionals looking to advise COPD patients on the use of these products. While ECs and HTPs may offer some benefits in reducing harm from cigarette smoke, their long-term effects on COPD patients' health are still unclear.

Analytic modeling and risk assessment of aerial transmission of SARS-CoV-2 virus through vaping expirations in shared micro-environments

It is well known that airborne transmission of COVID-19 in indoor spaces occurs through various respiratory activities: breathing, vocalizing, coughing, and sneezing. However, there is a complete lack of knowledge of its possible transmission through exhalations of e-cigarette aerosol (ECA), which is also a respiratory activity. E-cigarettes have become widely popular among smokers seeking a much safer way of nicotine consumption than smoking. Due to restrictive lockdown measures taken during the COVID-19 pandemic, many smokers and vapers (e-cigarette users) were confined to shared indoor spaces, making it necessary to assess the risk of SARS-CoV-2 virus aerial transmission through their exhalations. We summarize inferred knowledge of respiratory particles emission and transport through ECA, as well as a theoretical framework for explaining the visibility of exhaled ECA, which has safety implications and is absent in other respiratory activities (apart from smoking). We also summarize and briefly discuss the effects of new SARS-CoV-2 variants, vaccination rates, and environmental factors that may influence the spread of COVID-19. To estimate the risk of SARS-CoV-2 virus aerial transmission associated with vaping exhalations, we adapt a theoretical risk model that has been used to analyze the risks associated with other respiratory activities in shared indoor spaces. We consider home and restaurant scenarios, with natural and mechanical ventilation, with occupants wearing and not wearing face masks. We consider as "control case" or baseline risk scenario an indoor space (home and restaurant) where respiratory droplets and droplet nuclei are uniformly distributed and aerial contagion risk might originate exclusively from occupants exclusively rest breathing, assuming this to be the only (unavoidable) respiratory activity they all carry on. If an infected occupant uses an e-cigarette in a home or restaurant scenarios, bystanders not wearing face masks exposed to the resulting ECA expirations face a [Formula: see text] increase of risk of contagion with respect the control case. This relative added risk with respect to the control case becomes [Formula: see text] for high-intensity vaping, [Formula: see text], and over [Formula: see text] for speaking for various periods or coughing (all without vaping). Infectious emissions are significantly modified by mechanical ventilation, face mask usage, vaccination, and environmental factors, but given the lack of empiric evidence, we assume as a working hypothesis that all basic parameters of respiratory activities are equally (or roughly equally) affected by these factors. Hence, the relative risk percentages with respect to the control state should remain roughly the same under a wide range of varying conditions. By avoiding direct exposure to the visible exhaled vaping jet, wearers of commonly used face masks are well protected from respiratory droplets and droplet nuclei directly emitted by mask-less vapers. Compared to the control case of an already existing (unavoidable) risk from continuous breathing, vaping emissions in shared indoor spaces pose just a negligible additional risk of COVID-19 contagion. We consider that it is not necessary to take additional preventive measures beyond those already prescribed (1.5 m separation and wearing face masks) in order to protect bystanders from this contagion.

E-cigarette addiction and harm perception: Does initiation flavor choice matter?

Introduction

The 21^st century was marked by a dramatic increase in adolescent e-cigarette use in the United States (US). The popularity of non-traditional flavor types, including fruit and pastry, is thought to contribute toward growing product use nationally, leading to a variety of federal and state regulations limiting the use of non-traditional flavors in the US. The relationship between flavor type and increased adolescent use suggests a possible link between flavor use and addiction and harm perception. This study assessed if the flavor type used when initiating e-cigarette use predicted addiction and harm perceptions.

Methods

The study utilized data from the multi-wave youth Population Assessment of Tobacco Health Study. It explored the impact initiating e-cigarette use with traditional versus non-traditional flavor types among cigarette users on the outcome variables: e-cigarette addiction and harm perception. Both e-cigarette addiction and harm perception were measured using self-report, Likert scale questionnaires. Descriptive statistics characterized the study variables and linear regression analyses performed to test whether flavor initiation type is associated with addiction and harm perception.

Results

The study sample consisted of 1,043 youth (weighted N = 1,873,617) aged 12 to 17 years who reported at least one instance of e-cigarette use. After adjusting for age, age of onset, sex, race and annual household income there was no statistically significant difference in addiction levels between those initiating with traditional versus non-traditional flavors (p = 0.294). Similarly, traditional versus non-traditional flavor initiation did not show a statistically significant difference in adolescent e-cigarette harm perceptions (p = 0.601).

Conclusions

Traditionally flavored e-cigarette initiation produces similar risk for addiction and harm perceptions as non-traditionally flavored initiation. These findings suggest that banning non-traditional flavors alone may be ineffective in curbing e-cigarette addiction and harm perception. Additional research is needed to better understand which e-cigarette product characteristics and behaviors may be associated with greater addiction and reduced harm perceptions.

A randomised, open-label, cross-over clinical study to evaluate the pharmacokinetic, pharmacodynamic and safety and tolerability profiles of tobacco-free oral nicotine pouches relative to cigarettes

RATIONALE

Tobacco harm reduction (THR) involves encouraging adult smokers who would otherwise continue to smoke to transition to less harmful forms of nicotine delivery. These products must offer adult smokers reduced exposure to chemicals associated with tobacco combustion, satisfactory blood plasma nicotine levels and serve as an acceptable alternative. The most recent THR innovation is tobacco-free oral nicotine pouches.

OBJECTIVES

This study aimed to compare pharmacokinetic, pharmacodynamic and safety and tolerability profiles of two nicotine pouch variants (ZoneX #2 (5.8 mg nicotine/pouch); ZoneX #3 (10.1 mg nicotine/pouch)) with cigarette to assess the pouches' THR potential.

METHODS

This was a controlled use, randomised, open-label, cross-over clinical study with 24 healthy adult traditional tobacco users. Pharmacokinetic (plasma nicotine levels; up to 8 h post-use), pharmacodynamic (urge to smoke, product liking; up to 4 h post-use) and short-term safety and tolerability profiles were assessed.

RESULTS

Distinct nicotine pouch pharmacokinetic profiles indicated nicotine absorption via the oral mucosa. Plasma nicotine levels were lower, and time to peak slower, for the nicotine pouches compared to cigarette (Cmax cigarette: 11.6 ng/ml vs. #2: 5.2 ng/ml, p < 0.0001; #3: 7.9 ng/ml, p < 0.0003) (Tmax cigarette: 8.6 min vs. #2: 26 min; #3: 22 min). All products effectively reduced subjects' urge to smoke and presented favourable product liking scores; nicotine pouches were also well tolerated following short-term use (no serious adverse events).

CONCLUSIONS

Overall, the assessed ZoneX nicotine pouches may offer an acceptable alternative for adult smokers to achieve satisfactory levels of nicotine delivery and, based on the pharmacokinetic parameters and under the study conditions, likely have a lower abuse liability and addictive potential for current adult smokers compared to continued cigarette smoking.

CLINICAL TRIAL IDENTIFIER

NCT04891406 (clinicaltrials.gov).

Electronic cigarette related topics with conflicting arguments in Chinese newspapers

INTRODUCTION

While debates on e-cigarettes are mainly conducted in scientific fora, media are the most accessible information source for the public, shaping their perceptions of health issues. This study is the first to examine e-cigarette related topics with conflicting arguments presented in Chinese newspapers.

METHODS

The Chinese terms for ‘e-cigarettes’ were searched in a widely used Chinese news database Wisenews. Content analysis of the full text of 639 news articles was conducted to identify topics with conflicting arguments and examine whether the dominant argument in each topic changed across four time periods from 2004 to 2019.

RESULTS

Twelve e-cigarette related topics with conflicting arguments were identified. The most frequently reported topic was health impact of e-cigarettes, followed by impact of secondhand aerosol exposure, smoking cessation, relative health impact of e-cigarettes compared to cigarettes, and e-cigarette policies outside China. At the same time, the price was the least frequently reported topic. Overall, negative arguments outnumbered positive arguments in the study period. The dominant arguments within many topics changed across time periods; however, within the topics of relative health impact of e-cigarettes compared to cigarettes, taste/flavor, and economic prospects of the industry, positive arguments were more frequently reported in almost all periods. Within the topics of addiction, policies in China, and policies outside China, negative arguments were more frequently reported in virtually all periods.

CONCLUSIONS

Though overall the dominant argument about e-cigarettes and health was ‘e-cigarettes are harmful’, in the early time periods, e-cigarettes were reported as ‘harmless’ or even ‘healthy’. As China began to regulate e-cigarettes, the reporting on e-cigarettes more frequently included the ‘e-cigarettes are harmful’ argument. The consistent, more frequent reporting of ‘good e-cigarette taste/flavor’ has the potential to attract young people to e-cigarette products. The increased reporting on policies unfavorable to e-cigarettes aligned with the growing number of regulations restricting e-cigarettes.

Reductions in biomarkers of exposure to selected harmful and potentially harmful constituents following exclusive and partial switching from combustible cigarettes to myblu™ electronic nicotine delivery systems (ENDS)

Electronic nicotine delivery systems (ENDS) offer adult combustible cigarette smokers an alternative, potentially reduced harm, mode of nicotine delivery, attributed to fewer and reduced levels of harmful and potentially harmful constituents (HPHCs) in their aerosols compared to cigarette smoke. These two identical, randomised, open label, two-part studies aimed to compare levels of 15 biomarkers of exposure (BoE) to selected HPHCs associated with tobacco smoking in healthy US adult smoker subjects (n = 72). Following 9 days of exclusive use of a range of allocated myblu™ ENDS variants, subjects' levels of 14 non-nicotine BoE were substantially reduced compared to baseline values (combustible cigarette use), in the range of 46-97%. BoE reductions were sustained in subjects who continued myblu use exclusively (n = 25) for a further 5 days, and returned to near baseline levels in subjects who returned to exclusive combustible cigarette use (n = 21). Dual users (n = 24) demonstrated reductions in BoE to a lesser extent than with exclusive myblu use. Measured nicotine equivalents did not significantly change throughout the study. These data suggest exclusive use of ENDS provides adult smokers seeking an alternative to combustible cigarettes with substantial reductions in HPHC exposures whilst achieving satisfying levels of nicotine delivery. Dual use involving substitution of cigarettes may also provide some of this advantage, but to lesser extent. Overall, the data contribute to the weight of evidence that ENDS are an important tool in tobacco harm reduction for adult smokers unwilling to or uninterested in quitting smoking. Study 1: NCT04430634, study 2: NCT04429932, clinicaltrials.gov (10-06-2020).

Comparison of the in vivo genotoxicity of electronic and conventional cigarettes aerosols after subacute, subchronic and chronic exposures

Tobacco smoking is classified as a human carcinogen. A wide variety of new products, in particular electronic cigarettes (e-cigs), have recently appeared on the market as an alternative to smoking. Although the in vitro toxicity of e-cigs is relatively well known, there is currently a lack of data on their long-term health effects. In this context, the aim of our study was to compare, on a mouse model and using a nose-only exposure system, the in vivo genotoxic and mutagenic potential of e-cig aerosols tested at two power settings (18 W and 30 W) and conventional cigarette (3R4F) smoke. The standard comet assay, micronucleus test and Pig-a gene mutation assay were performed after subacute (4 days), subchronic (3 months) and chronic (6 months) exposure. The generation of oxidative stress was also assessed by measuring the 8-hydroxy-2'-deoxyguanosine and by using the hOGG1-modified comet assay. Our results show that only the high-power e-cig and the 3R4F cigarette induced oxidative DNA damage in the lung and the liver of exposed mice. In return, no significant increase in chromosomal aberrations or gene mutations were noted whatever the type of product. This study demonstrates that e-cigs, at high-power setting, should be considered, contrary to popular belief, as hazardous products in terms of genotoxicity in mouse model.

From Tobacco Cigarettes to Electronic Cigarettes: The Two Sides of a Nicotine Coin

Tobacco smoking-related diseases, including cardiovascular disease, pulmonary disease, stroke, and cancer in multiple organ sites, are the leading causes of preventable death, worldwide. Youth electronic cigarette use (vaping) is an evolving public health problem in the United States and around the world. Many of the same toxicants and carcinogens present in tobacco smoke are also found in electronic cigarette vapor, although mostly at substantially lower levels. The reduced concentrations of these chemicals in electronic cigarette vapor may imply lower health risk; however, they cannot equate to no risk. To date, the long-term health consequences of vaping are largely unknown. This “Perspective” provides a concise chronology of events leading up to an unprecedented global challenge, namely the convergence of global tobacco epidemic and youth vaping epidemic. Current state of knowledge, outstanding questions in the field, present challenges, and future directions in research are highlighted. The existing data show a continued and dynamic evolution of the converged epidemics. The goal should be to prevent youth vaping while improving smoking cessation strategies. In smokers who are unable or unwilling to quit smoking, the objective should be to provide “provably” safe or less-harmful alternatives, which should “completely” or “substantially” substitute tobacco cigarettes.

Balancing Consideration of the Risks and Benefits of E-Cigarettes

The topic of e-cigarettes is controversial. Opponents focus on e-cigarettes' risks for young people, while supporters emphasize the potential for e-cigarettes to assist smokers in quitting smoking. Most US health organizations, media coverage, and policymakers have focused primarily on risks to youths. Because of their messaging, much of the public-including most smokers-now consider e-cigarette use as dangerous as or more dangerous than smoking. By contrast, the National Academies of Science, Engineering, and Medicine concluded that e-cigarette use is likely far less hazardous than smoking. Policies intended to reduce adolescent vaping may also reduce adult smokers' use of e-cigarettes in quit attempts. Because evidence indicates that e-cigarette use can increase the odds of quitting smoking, many scientists, including this essay's authors, encourage the health community, media, and policymakers to more carefully weigh vaping's potential to reduce adult smoking-attributable mortality. We review the health risks of e-cigarette use, the likelihood that vaping increases smoking cessation, concerns about youth vaping, and the need to balance valid concerns about risks to youths with the potential benefits of increasing adult smoking cessation.

Impact of exclusive e-cigarettes and heated tobacco products use on muco-ciliary clearance

Background:

Tobacco smoking impairs mucociliary clearance (MCC) efficiency as shown by prolonged saccharin test transit time (STTT). Avoiding exposure to tobacco smoke from combustible cigarettes may restore MCC function and former smokers have been shown to exhibit similar STTT as never smokers. The impact on STTT of switching from smoking to combustion-free tobacco products such as e-cigarettes (ECs) and heated tobacco products (HTPs) is not known.

Methods:

We report STTT of exclusive EC and HTP users. Test results were compared with those obtained in current, former, and never smokers.

Results:

STTT were obtained from 39 current, 40 former, 40 never smokers, and from 20 EC and 20 HTP users. Comparison of STTT values showed significant difference among the five study groups (p < 0.00001) with current smokers having a median [interquartile range (IQR)] STTT of 13.15 min, which was significantly longer compared with that of all other study groups. In particular, compared with former (7.26 min) and never smokers (7.24 min), exclusive EC users and exclusive HTP users had similar STTT at 7.00 and 8.00 min, respectively.

Conclusion:

Former smokers who have switched to exclusive regular use of combustion-free nicotine delivery systems (i.e., ECs and HTPs) exhibit similar saccharin transit time as never and former smokers. This suggests that combustion-free nicotine delivery technologies are unlikely to have detrimental effects on MCC function.

Clinical Pharmacology of Electronic Nicotine Delivery Systems (ENDS): Implications for Benefits and Risks in the Promotion of the Combusted Tobacco Endgame

Electronic nicotine delivery systems (ENDS) such as e-cigarettes and heated tobacco products are novel battery-operated devices that deliver nicotine without combustion of tobacco. Because cigarette smoking is sustained by nicotine addiction and the toxic combustion products are mainly responsible for the harmful effects of smoking, ENDS could be used to promote smoking cessation while exposing users to lower levels of toxicants compared with conventional cigarettes. The currently available evidence from clinical and observational studies indicates a potential role of e-cigarettes as smoking cessation aids, although many continue to use e-cigarettes long after quitting smoking. Nicotine and toxicant delivery vary considerably by device and depend on the characteristics of the e-liquid formulation. Because smokers tend to titrate their nicotine intake to maintain their desired pharmacologic effects, device and liquid characteristics need to be considered when using ENDS as an aid to quit smoking. Factors potentially limiting their use are the currently still unknown long-term safety of these products and concerns regarding widespread use among youth. Implications of clinical pharmacology data on ENDS for the cigarette endgame and regulation by the U.S. Food and Drug administration are discussed.

Modeling Aerial Transmission of Pathogens (Including the SARS-CoV-2 Virus) through Aerosol Emissions from E-Cigarettes

We examine the plausibility of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets that might be carried by exhaled e-cigarette aerosol (ECA). Given the lack of empiric evidence on this phenomenon, we consider available evidence on cigarette smoking and respiratory droplet emission from mouth breathing through a mouthpiece as convenient proxies to infer the capacity of vaping to transport pathogens in respiratory droplets. Since both exhaled droplets and ECA droplets are within the Stokes regime, the ECA flow acts effectively as a visual tracer of the expiratory flow. To infer quantitatively the direct exposure distance, we consider a model that approximates exhaled ECA flow as an axially symmetric intermittent steady starting jet evolving into an unstable puff, an evolution that we corroborate by comparison with photographs and videos of actual vapers. On the grounds of all this theoretical modeling, we estimate for low-intensity vaping (practiced by 80–90% of vapers) the emission of 6–210 (median 39.9, median deviation 67.3) respiratory submicron droplets per puff and a horizontal distance spread of 1–2 m, with intense vaping possibly emitting up to 1000 droplets per puff in the submicron range with a distance spread over 2 m. The optical visibility of the ECA flow has important safety implications, as bystanders become instinctively aware of the scope and distance of possible direct contagion through the vaping jet.

The in vitro ToxTracker and Aneugen Clastogen Evaluation extension assay as a tool in the assessment of relative genotoxic potential of e-liquids and their aerosols

In vitro (geno)toxicity assessment of electronic vapour products (EVPs), relative to conventional cigarette, currently uses assays, including the micronucleus and Ames tests. Whilst informative on induction of a finite endpoint and relative risk posed by test articles, such assays could benefit from mechanistic supplementation. The ToxTracker and Aneugen Clastogen Evaluation analysis can indicate the activation of reporters associated with (geno)toxicity, including DNA damage, oxidative stress, the p53-related stress response and protein damage. Here, we tested for the different effects of a selection of neat e-liquids, EVP aerosols and Kentucky reference 1R6F cigarette smoke samples in the ToxTracker assay. The assay was initially validated to assess whether a mixture of e-liquid base components, propylene glycol (PG) and vegetable glycerine (VG) had interfering effects within the system. This was achieved by spiking three positive controls into the system with neat PG/VG or phosphate-buffered saline bubbled (bPBS) PG/VG aerosol (nicotine and flavour free). PG/VG did not greatly affect responses induced by the compounds. Next, when compared to cigarette smoke samples, neat e-liquids and bPBS aerosols (tobacco flavour; 1.6% freebase nicotine, 1.6% nicotine salt or 0% nicotine) exhibited reduced and less complex responses. Tested up to a 10% concentration, EVP aerosol bPBS did not induce any ToxTracker reporters. Neat e-liquids, tested up to 1%, induced oxidative stress reporters, thought to be due to their effects on osmolarity in vitro. E-liquid nicotine content did not affect responses induced. Additionally, spiking nicotine alone only induced an oxidative stress response at a supraphysiological level. In conclusion, the ToxTracker assay is a quick, informative screen for genotoxic potential and mechanisms of a variety of (compositionally complex) samples, derived from cigarettes and EVPs. This assay has the potential for future application in the assessment battery for next-generation (smoking alternative) products, including EVPs.

Respiratory and Cardiovascular Health Effects of e-Cigarette Substitution: Protocol for Two Living Systematic Reviews

Background

Despite the clear risks of tobacco use, millions of people continue to smoke. Electronic nicotine delivery systems (ENDS), commonly called e-cigarettes, have been proposed as a substitute for those who are unwilling or unable to quit. Current systematic and narrative reviews on the health effects of ENDS use, particularly respiratory and cardiovascular effects, have come to differing conclusions.

Objective

We conducted two systematic reviews to critically assess and synthesize available human studies on the respiratory and cardiovascular health effects of ENDS substitution for people who smoke. The primary goal is to provide clinicians with evidence on the health effects of ENDS substitution to inform their treatment recommendations and plans. The twin goal of the reviews is to promote health literacy in ENDS users with facts on the health effects of ENDS.

Methods

These two reviews will be living systematic reviews. The systematic reviews will be initiated through a baseline review. Studies will be evaluated using the JBI quality assessment tools and a checklist of biases drawn from the Centre for Evidence Based Medicine Catalogue of Bias. A narrative synthesis is planned because of the heterogeneity of data. A search for recently published studies will be conducted every 3 months, and an updated review will be published every 6 months for the duration of the project or possibly longer.

Results

The baseline and updated reviews will be published in a peer-reviewed journal. The findings of the reviews will be reported in a white paper for clinicians and a fact sheet for people who use ENDS.

Conclusions

The substitution of ENDS for cigarettes is one way to potentially reduce the risks of smoking. Clinicians and their patients need to understand the potential benefits and possible risks of substituting ENDS for cigarettes. Our living systematic reviews seek to highlight the best and most up-to-date evidence in this highly contentious and fast-moving field of research.

Trial Registration

PROSPERO CRD42021239094; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=239094

International Registered Report Identifier (IRRID)

DERR1-10.2196/29084

International randomised controlled trial evaluating metabolic syndrome in type 2 diabetic cigarette smokers following switching to combustion-free nicotine delivery systems: the DIASMOKE protocol

INTRODUCTION

Reducing exposure to cigarette smoke is an imperative for public health and for patients with diabetes. Increasingly, combustion-free nicotine delivery systems (C-F NDS) such as e-cigarettes and heated tobacco products are substituting conventional cigarettes and accelerating the downward trends in smoking prevalence. However, there is limited information about the long-term health impact in patients with diabetes who use C-F NDS. This randomised trial of type 2 diabetic cigarette smokers will test the hypothesis that following a switch from conventional cigarettes to C-F NDS a measurable improvement in metabolic syndrome (MetS) factors will be shown over the course of 2 years.

METHODS AND ANALYSIS

The study is multicentre and thus will take place in five locations in four countries in an ambulatory setting. A total of 576 patients with diabetes will be randomised (1:2 ratio) to either a control arm (Study Arm A), in which they will be offered referral to smoking cessation programmes or to an intervention arm (Study Arm B) assigned to C-F NDS use. Participants will be at least 23 years old and of any gender. Patient recruitment will start in February 2021 and is expected to be completed by December 2021. Primary outcome measures include fasting plasma glucose, blood pressure, triglycerides, high-density lipoprotein and waist circumference, while secondary feature absolute change in the sum of the individual factors of MetS and change in each individual factor of MetS measured at each study time point.

ETHICS AND DISSEMINATION

The approval of research ethics committee (REC) regarding the trial protocol, informed consent forms and other relevant documents is required to commence the study. Substantial amendments to the study protocol cannot be implemented until the REC grants a favourable opinion. The results of the study are intended to be published as articles in high quality peer-reviewed journals and disseminated through conference papers.

TRIAL REGISTRATION NUMBER

NCT04231838. Pre-results stage.

Nicotine dosimetry and stability in cambridge filter PADs (CFPs) following different smoking regime protocols and storage conditions

Despite the growing numbers of studies on cigarettes and electronic nicotine delivery products (ENDs), no standard assessment of nicotine stability in various matrix post exposure is currently available. The aim of the present study was to evaluate the optimal standard condition to store Cambridge Filter Pads (CFPs) before chemical analysis in order to guarantee the titer of nicotine.We further performed data normalization according to different smoking or vaping runs. Smoke and vapor generated respectively by a reference tobacco cigarette (1R6F) and ENDs under different exposure regimes (ISO, HCI and CRM81) were collected on CFPs as total particulate matter (TPM) and subsequently analyzed for nicotine content. For each exposure, some CFPs were analyzed at time zero, whereas the others were stored under different conditions for nicotine assessment after 30 days. Principal Component Analysis (PCA) showed the best correlation between nicotine on CFPs and TPM for normalization. This study suggests that different exposure regimes and products can affect the preservation of nicotine titer on CFPs while samples storage at -80 °C may prevent the loss of nicotine. Finally, normalization of nicotine with TPM is strongly recommended for regulatory purpose.

Critical appraisal of the European Union Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) Preliminary Opinion on electronic cigarettes

BACKGROUND

In preparation for the 2021 revision of the European Union Tobacco Products Directive, the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) has posted its Preliminary Opinion on Electronic Cigarettes. They concluded that e-cigarettes only achieve a sub-optimal level of protection of human health. In this paper, we provide evidence that the Opinion's conclusions are not adequately backed up by scientific evidence and did not discuss the potential health benefits of using alternative combustion-free nicotine-containing products as substitute for tobacco cigarettes.

METHODS

Searches for articles were conducted in PubMed and by citation chasing in Google Scholar. Articles were also retrieved with a review of references in major publications. Primary data from World Health Organization surveys, the conclusions of reviews, and peer-reviewed non-industry studies were cited to address errors and omissions identified in the Opinion.

RESULTS

The Opinion omitted reporting on the individual and population health benefits of the substitution of e-cigarettes (ENDS) for cigarette smoking. Alternative hypotheses to the gateway theory were not evaluated. Its assessment of cardiovascular risk is contradicted by numerous reviews. It cites ever-use data that do not represent current patterns of use. It did not report non-nicotine use. It presented erroneous statements on trends in ENDS prevalence. It over-emphasized the role of flavours in youth ENDS initiation. It did not discuss cessation in sufficient length.

CONCLUSIONS

For the delivery of a robust and comprehensive final report, the members of the Working Group of the Scientific Committee on Health, Environmental and Emerging Risks will need to consider (1) the potential health benefits of ENDS substitution for cigarette smoking, (2) alternative hypotheses and contradictory studies on the gateway effect, (3) its assessment of cardiovascular risk, (4) the measurements of frequency of use, (5) non-nicotine use, (6) the role of flavours, and (7) a fulsome discussion of cessation.

Aerial Transmission of the SARS-CoV-2 Virus through Environmental E-Cigarette Aerosols: Implications for Public Policies

We discuss the implications of possible contagion of COVID-19 through e-cigarette aerosol (ECA) for prevention and mitigation strategies during the current pandemic. This is a relevant issue when millions of vapers (and smokers) must remain under indoor confinement and/or share public outdoor spaces with non-users. The fact that the respiratory flow associated with vaping is visible (as opposed to other respiratory activities) clearly delineates a safety distance of 1-2 m along the exhaled jet to prevent direct exposure. Vaping is a relatively infrequent and intermittent respiratory activity for which we infer a mean emission rate of 79.82 droplets per puff (6-200, standard deviation 74.66) comparable to mouth breathing, it adds into shared indoor spaces (home and restaurant scenarios) a 1% extra risk of indirect COVID-19 contagion with respect to a "control case" of existing unavoidable risk from continuous breathing. As a comparative reference, this added relative risk increases to 44-176% for speaking 6-24 min per hour and 260% for coughing every 2 min. Mechanical ventilation decreases absolute emission levels but keeps the same relative risks. As long as direct exposure to the visible exhaled jet is avoided, wearing of face masks effectively protects bystanders and keeps risk estimates very low. As a consequence, protection from possible COVID-19 contagion through vaping emissions does not require extra interventions besides the standard recommendations to the general population: keeping a social separation distance of 2 m and wearing of face masks.

Vaping and lung cancer - A review of current data and recommendations

OBJECTIVES

Lung cancer is the most common cause of cancer mortality worldwide and, while tobacco smoke remains the primary cause, there is increasing concern that vaping and E-cigarette use may also increase lung cancer risk. This review concentrates on the current data, scholarship and active foci of research regarding potential cancer risk and oncogenic mechanisms of vaping and lung cancer.

MATERIALS AND METHODS

We performed a literature review of current and historical publications on lung cancer oncogenesis, vaping device/e-liquid contents and daughter products, molecular oncogenic mechanisms and the fundamental, potentially oncogenic, effects of electronic cigarette smoke/e-liquid products.

RESULTS

E-cigarette devices and vaping fluids demonstrably contain a series of both definite and probable oncogens including nicotine derivatives (e.g. nitrosnornicotine, nitrosamine ketone), polycyclic aromatic hydrocarbons, heavy metals (including organometal compounds) and aldehydes/other complex organic compounds. These arise both as constituents of the e-liquid (with many aldehydes and other complex organics used as flavourings) and as a result of pyrolysis/complex organic reactions in the electronic cigarette device (including unequivocal carcinogens such as formaldehyde - formed from pyrolysis of glycerol). Various studies demonstrate in vitro transforming and cytotoxic activity of these derivatives. E-cigarette device use has been significantly increasing - particularly amongst the younger cohort and non-smokers; thus, this is an area of significant concern for the future.

CONCLUSION

Although research remains somewhat equivocal, there is clear reason for concern regarding the potential oncogenicity of E-Cigarettes/E-Liquids with a strong basic and molecular science basis. Given lag times (extrapolating from tobacco smoke data) of perhaps 20 years, this may have significant future public health implications. Thus, the authors feel further study in this field is strongly warranted and consideration should be made for tighter control and regulation of these products.

Reasons why Chinese smokers prefer not to use electronic cigarettes

INTRODUCTION

China is the world’s largest e-cigarette manufacturer. It also has the world’s largest smoking population. Although smoking is strongly associated with e-cigarette use, the prevalence of e-cigarette use is low among Chinese smokers compared with smokers in countries such as the US and UK. This study aims to explore the reasons why Chinese smokers prefer not to use e-cigarettes.

METHODS

Cross-sectional data from the Tobacco Questions for Surveys (TQS) conducted in four large Chinese cities (Chengdu, Wuhan, Xiamen, and Xi’an) in 2017–2018 were analyzed. A multi-stage cluster sampling approach was applied to select a representative sample of adults for each city. Weighted percentages and 95% confidence intervals (CIs) were estimated for self-reported reasons why smokers in China had never tried e-cigarettes, in total and by demographic characteristics. Multivariate logistic regression models were used to examine the adjusted associations between the top reasons why smokers never tried e-cigarettes and demographic and socioeconomic characteristics.

RESULTS

The top three reasons that Chinese adult smokers reported for never having tried e-cigarettes were: ‘I do not want to quit smoking’ (35.35%), ‘I do not think they would help me quit or cut down’ (24.31%), and ‘I am not addicted to smoking and don't need help to quit’ (14.93%). Other prominent reasons included: ‘I am concerned they are not safe enough’, and ‘I do not want to substitute one addiction for another’. Generally, there were no statistically significant associations between reasons why smokers never tried e-cigarettes and demographic and socioeconomic characteristics.

CONCLUSIONS

Our results suggest that many Chinese smokers associate e-cigarette use with smoking cessation. Continued monitoring of smokers’ views, beliefs, and risk perceptions regarding e-cigarettes is warranted. Health education campaigns communicating the risks of e-cigarettes are also needed.

Exclusive E-Cigarette Users Report Lower Levels of Respiratory Symptoms Relative to Dual E-Cigarette and Cigarette Users

INTRODUCTION

Exclusive e-cigarette use has been shown to be associated with reduced levels of respiratory symptoms relative to smoking combustible cigarettes; this association has been less frequently studied in smokers using advanced-generation e-cigarette devices. Advanced-generation devices generate denser vapor than either early generation or pod-style devices, and engender longer inhalations; these vaping topography patterns may contribute to respiratory symptoms.

METHODS

In a single-session, cross-sectional study of exclusive e-cigarette users (N = 59) and dual users of e-cigarettes and cigarettes (N = 54), participants completed questionnaires, including the American Thoracic Society Questionnaire (ATSQ) and were videotaped vaping their own device in the lab for 1 hour. Using a hierarchical regression method, we examined whether topography variables, level of nicotine concentration used in their e-cigarette device in the past month, e-cigarette dependence, amount of e-cigarette use in the past month, and smoking status (any smoking in the last month vs. none) predicted ATSQ score severity.

RESULTS

There was a significant mean difference in ATSQ score across smoking status, with greater ATSQ scores for vapers who also smoked cigarettes (19.0, SD = 6.7) than for exclusive vapers (13.4, SD = 5.3). In the final model, of the predictors of interest, only cigarette smoking status predicted significantly greater ATSQ scores (overall F = 2.51, p = .006; R2 = .26; smoking status β = 0.39, p < .0001).

CONCLUSIONS

Findings suggest that differences in respiratory symptoms between dual and exclusive e-cigarette users appear to be attributable to combustible cigarette smoking, rather than more intense or frequent e-cigarette use across groups.

IMPLICATIONS

In this comparison of exclusive advanced-generation vape device users (N = 59) versus dual users of these devices and combustible cigarettes (N = 54), we set out to determine the extent to which smoking status and e-cigarette use variables predicted self-reported respiratory symptom severity. We found that dual users showed greater respiratory symptom severity (ATSQ scores) than exclusive vapers. Despite examining vaping topography and other variables, smoking status and race were the only significant predictor of respiratory symptoms. We conclude that combustible cigarette use, not individual vaping topography, likely accounts for differences in respiratory symptoms between dual users and exclusive vapers.

Use of Electronic Cigarettes and Self-Reported Chronic Obstructive Pulmonary Disease Diagnosis in Adults

INTRODUCTION

Electronic cigarette (e-cigarette) use (vaping) has increased in recent years. Chronic obstructive pulmonary disease (COPD) is the third leading cause of death associated with smoking.

AIMS AND METHODS

Based on 2016 and 2017 Behavioral Risk Factor Surveillance System national survey data on 891 242 adult participants who indicated their smoking and vaping status, the cross-sectional association of vaping with self-reported COPD diagnosis was investigated, using univariable and multivariable weighted logistic regression models.

RESULTS

Compared to never users, while dual users showed the highest association with self-reported COPD diagnosis (adjusted odds ratio [aOR] = 4.39; 95% confidence interval [CI] = 3.98 to 4.85), current vapers who were either ex-smokers or never smoked showed significantly higher association with self-reported COPD diagnosis (aOR = 3.24; 95% CI = 2.78 to 3.78 and aOR = 1.47; 95% CI = 1.01 to 2.12, respectively). Current vapers who were ex-smokers showed higher association with self-reported COPD diagnosis than ex-smokers who do not vape (aOR = 1.27; 95% CI = 1.09 to 1.48). Dual users showed higher association with self-reported COPD diagnosis than current smokers who do not vape (aOR = 1.16; 95% CI = 1.05 to 1.27). Ex-smokers showed significantly less association with self-reported COPD diagnosis (aOR = 0.67; 95% CI = 0.64 to 0.71) than current smokers. Current vapers who were either ex-smokers or never smoked had less association with self-reported COPD diagnosis compared to current smokers, with aOR = 0.85 (95% CI = 0.73 to 0.99) and aOR = 0.39 (95% CI = 0.27 to 0.56).

CONCLUSIONS

Vaping is significantly associated with self-reported COPD diagnosis in adults, even among vapers who never smoked. Whether there is a benefit for COPD of switching from smoking to vaping requires study of the long-term effects of vaping.

IMPLICATIONS

With the increase of e-cigarette use in recent years, the health effects of e-cigarettes need to be investigated. While several studies have examined the association of vaping with respiratory symptoms among adolescents, little is known about the association of vaping with susceptibility to COPD among US adults. Using cross-sectional national survey data in adults, our study showed that vaping was significantly associated with self-reported COPD diagnosis. Although our data did not establish the causal relationship between vaping and self-reported COPD diagnosis, this study raises concerns about the observed association between vaping and self-reported COPD diagnosis.

Reactions to messages about smoking, vaping and COVID-19: two national experiments

Introduction

The pace and scale of the COVID-19 pandemic, coupled with ongoing efforts by health agencies to communicate harms, have created a pressing need for data to inform messaging about smoking, vaping, and COVID-19. We examined reactions to COVID-19 and traditional health harms messages discouraging smoking and vaping.

Methods

Participants were a national convenience sample of 810 US adults recruited online in May 2020. All participated in a smoking message experiment and a vaping message experiment, presented in a random order. In each experiment, participants viewed one message formatted as a Twitter post. The experiments adopted a 3 (traditional health harms of smoking or vaping: three harms, one harm, absent) × 2 (COVID-19 harms: one harm, absent) between-subjects design. Outcomes included perceived message effectiveness (primary) and constructs from the Tobacco Warnings Model (secondary: attention, negative affect, cognitive elaboration, social interactions).

Results

Smoking messages with traditional or COVID-19 harms elicited higher perceived effectiveness for discouraging smoking than control messages without these harms (all p <0.001). However, including both traditional and COVID-19 harms in smoking messages had no benefit beyond including either alone. Smoking messages affected Tobacco Warnings Model constructs and did not elicit more reactance than control messages. Smoking messages also elicited higher perceived effectiveness for discouraging vaping. Including traditional harms in messages about vaping elicited higher perceived effectiveness for discouraging vaping (p <0.05), but including COVID-19 harms did not.

Conclusions

Messages linking smoking with COVID-19 may hold promise for discouraging smoking and may have the added benefit of also discouraging vaping.

GC-MS analysis of e-cigarette refill solutions: A comparison of flavoring composition between flavor categories

OBJECTIVES

Electronic cigarette refill solutions (e-liquids) are available in various flavor descriptions that can be categorized as fruit, tobacco, and more. Flavors increase sensory appeal, thereby stimulating e-cigarette use, and flavoring ingredients can contribute to e-cigarette toxicity. We aim to inform toxicologists, sensory scientists, and regulators by determining flavoring compounds in e-liquids with various flavors, and compare results between flavor categories.

METHODS

Gas chromatography - mass spectrometry (GC-MS) was used to identify 79 flavorings in 320 e-liquids, classified in 15 flavor categories. Ten flavorings highly prevalent in e-liquids according to information from manufacturers were quantified. Flavoring prevalence was defined as the number of e-liquids with the flavoring as percentage of the total number of e-liquids. The method was validated in terms of specificity, linearity, repeatability, recovery, and sensitivity.

RESULTS

The mean number of flavorings per e-liquid was 6 ± 4. Flavoring prevalence was highest for vanillin (creamy/vanilla flavor), ethyl butyrate (ethereal/fruity), and cis-3-hexenol (fresh/green). Based on similarities in flavoring prevalence, four clusters of categories were distinguished: (1) fruit, candy, alcohol, beverages; (2) dessert, coffee/tea, nuts, sweets; (3) menthol/mint; and (4) spices, tobacco, and unflavored. Categories from cluster 4 generally had less flavorings per e-liquid than fruit, candy, alcohol, beverages (cluster 1) and dessert (cluster 2) (p < 0.05). Flavoring concentrations varied between e-liquids within the categories.

CONCLUSIONS

We evaluated flavoring compositions of 320 e-liquids using a simple GC-MS method. Flavoring prevalence was similar within four clusters of typically fresh/sweet, warm/sweet, fresh/cooling, and non-sweet flavor categories. To compare flavoring concentrations between individual flavor categories, additional research is needed.

E-vapor aerosols do not compromise bone integrity relative to cigarette smoke after 6-month inhalation in an ApoE-/- mouse model

Cigarette smoke (CS) exposure is one of the leading risk factors for human health. Nicotine-containing inhalable products, such as e-cigarettes, can effectively support tobacco harm reduction approaches. However, there are limited comparative data on the effects of the aerosols generated from electronic vapor products (e-vapor) and CS on bone. Here, we report the effects of e-vapor aerosols and CS on bone morphology, structure, and strength in a 6-month inhalation study. Eight-week-old ApoE^-/- mice were exposed to aerosols from three different e-vapor formulations-CARRIER (propylene glycol and vegetable glycerol), BASE (CARRIER and nicotine), TEST (BASE and flavor)-to CS from 3R4F reference cigarettes at matched nicotine concentrations (35 µg/L) or to fresh air (Sham) (N = 10 per group). Tibiae were analyzed for bone morphology by µCT imaging, biomechanics by three-point bending, and by histological analysis. CS inhalation caused a significant decrease in cortical and total bone volume fraction and bone density relative to e-vapor aerosols. Additionally, CS exposure caused a decrease in ultimate load and stiffness. In contrast, bone structural and biomechanical parameters were not significantly affected by e-vapor aerosol or Sham exposure. At the dissection time point, there was no significant difference in body weight or tibia bone weight or length among the groups. Histological findings revealed microcracks in cortical bone areas among all exposed groups compared to Sham control. In conclusion, because of the bone-preserving effect of e-vapor aerosols relative to CS exposure, e-vapor products could potentially constitute less harmful alternatives to cigarettes in situations in which bone health is of importance.

Benefits of e-cigarettes in smoking reduction and in pulmonary health among chronic smokers undergoing a lung cancer screening program at 6 months

INTRODUCTION

Electronic cigarettes (e-cigarettes) might be a valid and safe device to support smoking cessation. However, the available evidence is divergent. The aim of the present work was to assess the effects of an e-cigarette program on pulmonary health (cough, breath shortness, catarrh) and to evaluate the effectiveness of e-cigarettes in reducing tobacco consumption.

METHODS

The study is a double-blind randomized controlled trial. Two hundred and ten smokers were randomized into three groups: nicotine e-cigarette (8 mg/mL nicotine concentration), nicotine-free e-cigarettes (placebo), and control with 1:1:1 ratio. All participants received a 3 months cessation program that included a cognitive-behavioral intervention aimed at supporting people in changing their behavior and improving motivation to quit.

RESULTS

Pulmonary health, assessed with self-reported measures, clinical evaluations and the Leicester Cough Questionnaire, improved in participants who stopped smoking compared to their own baseline. No differences in pulmonary health were found between groups. Statistical tests showed a significant effect of Group (F (2, 118) = 4.005, p < .020) on daily cigarette consumption: after 6 months participants in the nicotine e-cigarette group smoked fewer cigarettes than any other group. Moreover, participants in this group showed the lowest level of exhaled carbon monoxide (CO) (M = 12.012, S.D. = 8.130), and the lowest level of dependence (M = 3.12, S.D. = 2.29) compared to the nicotine-free e-cigarette and control conditions.

CONCLUSIONS

After 6 months about 20% of the entire sample stopped smoking. Participants who used e-cigarettes with nicotine smoked fewer tobacco cigarettes than any other group after 6 months (p < .020). Our data add to the efficacy and safety of e-cigarettes in helping smokers reducing tobacco consumption and improving pulmonary health status.