Nicotine, Carcinogen, and Toxin Exposure in Long-Term E-Cigarette and Nicotine Replacement Therapy Users: A Cross-sectional Study

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.

Impact of the FDA flavour enforcement policy on flavoured electronic cigarette use behaviour changes

INTRODUCTION

This study aims to investigate electronic cigarette (e-cigarette) use behaviour changes after the implementation of the US Food and Drug Administration (FDA) restriction on the sale of all unauthorised flavoured cartridge-based e-cigarettes other than tobacco and menthol flavour on 6 February 2020, as well as factors associated with these changes.

METHODS

Through Amazon's Mechanical Turk service, 3533 current adult flavoured e-cigarette users (who were not exclusive tobacco-flavoured or menthol-flavoured e-cigarette users) were recruited for an online survey from 8 July to 29 July 2021. Multiple logistic regression models were used to identify significant factors associated with quitting e-cigarette use, switching to other flavoured electronic nicotine delivery system (ENDS) products, switching to combustible tobacco products, switching to menthol-flavoured e-cigarettes and switching to tobacco-flavoured e-cigarettes.

RESULTS

Resulting from the FDA flavour enforcement policy, the top four e-cigarette use behaviour changes were: (1) switching to other flavoured ENDS products such as the tank system or disposable e-cigarettes (29.24%), (2) switching to menthol-flavoured pod systems (18.09%), (3) switching to combustible tobacco products (14.12%) and (4) switching to tobacco-flavoured pod systems (12.03%). There were 4.9% participants who indicated that they quit e-cigarette use. Overall, multiple factors, especially past 30-day use of certain flavours, were associated with different behaviour changes.

CONCLUSIONS

The implementation of the FDA flavour enforcement policy on cartridge-based e-cigarette was associated with significant e-cigarette behaviour changes, with multiple factors being associated with these changes. These results provide important information for future regulations of flavoured e-cigarette products.

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.

The Health Effects of Real-World Dual Use of Electronic and Conventional Cigarettes versus the Health Effects of Exclusive Smoking of Conventional Cigarettes: A Systematic Review

BACKGROUND

A high prevalence of dual use of e-cigarettes and conventional cigarettes has been reported across the world.

METHODS

A systematic search was carried out. We included original articles on any topic relevant to health, excluding mental health, in all languages. The PRISMA guidelines were followed. Both reviewers independently screened and read all publications. We compared dual use with exclusive smoking of conventional cigarettes (ESCC).

RESULTS

Fifty-two publications (49 studies) were included. Thirteen papers/10 studies were prospective. There was great heterogeneity across studies. Many methodological weaknesses, such as inaccurate exposure measurement, lack of adjustment for former tobacco consumption, and lack of significance testing were identified. Most prospective studies found dual use to be at least as harmful as ESCC. The longest follow-up was six years. Most of the best available cross-sectional studies found dual use associated with the same and, in several studies, significantly higher risk of self-reported symptoms/disease than in ESCC. The intensity of cigarette smoking seems associated with worse health.

CONCLUSION

Existing studies indicate that dual use is at least as, or probably even more, harmful than ESCC. Due to the predominance of cross-sectional studies and the methodological weaknesses we judged the overall certainty of the evidence as "low certainty".

A Decision-Theoretic Public Health Framework for Heated Tobacco and Nicotine Vaping Products

Markets for nicotine vaping products (NVPs) and heated tobacco products (HTPs) have grown as these products became positioned as harm-reduction alternatives to combusted tobacco products. Herein, we present a public health decision-theoretic framework incorporating different patterns of HTP, NVP, and cigarette use to examine their impacts on population health. Our framework demonstrates that, for individuals who would have otherwise smoked, HTP use may provide public health benefits by enabling cessation or by discouraging smoking initiation and relapse. However, the benefits are reduced if more harmful HTP use replaces less harmful NVP use. HTP use may also negatively impact public health by encouraging smoking by otherwise non-smokers or by encouraging initiation or relapse into smoking. These patterns are directly influenced by industry behavior as well as public policy towards HTPs, NVPs, and cigarettes. While substantial research has been devoted to NVPs, much less is known about HTPs. Better information is needed to more precisely define the health risks of HTPs compared to cigarettes and NVPs, the relative appeal of HTPs to consumers, and the likelihood of later transitioning to smoking or quitting all products. While our analysis provides a framework for gaining that information, it also illustrates the complexities in distinguishing key factors.

When Hotel Guests Complain About Tobacco, Electronic Cigarettes, and Cannabis: Lessons for Implementing Smoking Bans

We analyzed reviews on tripadvisor.com from a random sample of N = 477 hotels in ten large cities in the US to examine how well existing policies protect guests from exposure to tobacco, electronic cigarette, and cannabis (TEC) smoke. We examined the association between complaints per 100 reviews with hotel smoking policies, star rating, cost, brand, and location. Of all TEC complaints, 80% were associated with thirdhand smoke residue lingering in hotels from previous guests. Compared to the hotel brands with the best records, the two worst-performing brands had 3.4- and 3.6-times higher complaint rates (P < .001). Hotels with ≤2-star ratings had twice the complaints as higher-rated hotels (P < .001). Compared to 100% smokefree hotels, those offering designated smoking rooms had a 35% higher rate of complaints (P < .05). The success of some hotel brands demonstrates it is feasible to protect guests by fully committing to, implementing, and enforcing 100% smokefree building policies.

The Australia Smoking and Vaping Model: The Potential Impact of Increasing Access to Nicotine Vaping Products

BACKGROUND

We model the potential impact of relaxing current nicotine vaping product (NVP) restrictions on public health in Australia.

AIMS AND METHODS

A Restricted NVP Scenario was first developed to project current smoking and vaping rates, where a U.S. smoking model was calibrated to recent Australian trends. To model less restrictive NVP policies, a Permissive NVP Scenario applied rates of switching from smoking to vaping, initiation into NVP and cigarette use, and cessation from smoking and vaping based on U.S. trends. The model measures vaping risk relative to the excess mortality rate of smoking. The public health impacts are measured as the difference between smoking- and vaping-attributable deaths (SVADs) and life years lost (LYLs) in the Restricted and Permissive NVP Scenarios. Sensitivity analysis is conducted regarding the NVP excess risk and other factors.

RESULTS

Assuming an NVP excess risk of 5% that of smoking, 104.2 thousand SVADs (7.7% reduction) and 2.05 million LYLs (17.3% reduction) are averted during 2017-2080 in the Permissive NVP Scenario compared to the Restricted NVP Scenario. Assuming 40% NVP excess risk, 70 thousand SVADs and 1.2 million LYLs are averted. The impact is sensitive to the rate at which smokers switch to NVPs and quit smoking, and relatively insensitive to the smoking initiation and NVP initiation and cessation rates.

CONCLUSIONS

The model suggests the potential for public health gains to be achieved by relaxing NVP access regulations. However, the model would benefit from better information regarding the impact of NVPs on smoking under a relaxation of current restrictions.

IMPLICATIONS

Australia has implemented a strong array of cigarette-oriented policies, but has restricted access to NVPs. The Smoking and Vaping Model offers a framework for modeling hypothetical policy scenarios. The Australian model shows the potential for public health gains by maintaining cigarette-oriented policies while relaxing the current restrictive NVP policy. Modeling results under a permissive NVP policy are particularly sensitive to the estimated rates of smoking cessation and switching to vaping, which are not well established and will likely depend on past and future cigarette-oriented policies and the specific NVP policies implemented in Australia.

Risk and safety profile of electronic nicotine delivery systems (ENDS): an umbrella review to inform ENDS health communication strategies

OBJECTIVES

This umbrella review aims to summarise the evidence about electronic nicotine delivery systems' (ENDS) risk and safety health profile to inform ENDS health communication strategies.

DATA SOURCES AND STUDY SELECTION

Six databases were searched for systematic reviews presenting evidence on ENDS-related health effects. Ninety reviews divided into five categories were included: toxicity=20, health effects=40, role in smoking cessation=24, role in transition to combustible cigarettes (CCs)=13 and industry marketing claims=4.

DATA EXTRACTION

Findings were synthesised in narrative summaries. Meta-analyses were conducted by study type when appropriate. Quality assessment was conducted using the Measurement Tool to Assess Systematic Reviews. The Institute of Medicine's Levels of Evidence Framework was used to classify the evidence into high-level, moderate, limited-suggestive and limited-not-conclusive.

DATA SYNTHESIS

We found high-level evidence that ENDS exposes users to toxic substances; increases the risk of respiratory disease; leads to nicotine dependence; causes serious injuries due to explosion or poisoning; increases smoking cessation in clinical trials but not in observational studies; increases CC initiation; and exposure to ENDS marketing increases its use/intention to use. Evidence was moderate for ENDS association with mental health and substance use, limited-suggestive for cardiovascular, and limited-not-conclusive for cancer, ear, ocular and oral diseases, and pregnancy outcomes.

CONCLUSIONS

As evidence is accumulating, ENDS communication can focus on high-level evidence on ENDS association with toxicity, nicotine addiction, respiratory disease, ENDS-specific harm (explosion, poisoning) and anti-ENDS industry sentiment. Direct comparison between the harm of CCs and ENDS should be avoided.

PROSPERO REGISTRATION NUMBER

CRD42021241630.

Urgent Need for Novel Investigations of Treatments to Quit E-cigarettes: Findings from a Systematic Review

E-cigarette use has been increasing globally over the past decade. Many use e-cigarettes as an alternative or method to quit cigarette smoking, whereas others use these products recreationally. As technology has advanced, many individuals have reported symptoms of dependence on these products and continue to use them beyond achieving abstinence from smoking. Despite individuals reporting interest in quitting, little is known about e-cigarette cessation. This systematic review sought to identify and evaluate all human subjects literature published on the outcome of e-cigarette cessation through September 2021. Of the 79 articles identified, 56 were cross-sectional, 6 were qualitative, 5 were cohort studies, 3 were experimental, 2 were mixed methods, and 7 reported intervention or case studies of e-cigarette cessation. Results showed youth generally had high intent to quit e-cigarettes, whereas results were mixed with adult samples. Youth were motivated to quit e-cigarettes by health concerns, whereas adults were motivated to quit e-cigarettes by cost, lack of satisfaction, and psychologic factors. Adults were more likely to report past e-cigarette quit attempts, most commonly "cold turkey." Few interventions tested strategies for e-cigarette cessation, with a majority targeted for youth. Given the lack of information on e-cigarette cessation, recommendations for future studies are outlined.

Propylene glycol, a component of electronic cigarette liquid, damages epithelial cells in human small airways

Background

Electronic cigarettes (e-cigarettes) are used worldwide as a substitute for conventional cigarettes. Although they are primarily intended to support smoking cessation, e-cigarettes have been identified as a gateway to smoking habits for young people. Multiple recent reports have described the health effects of inhaling e-cigarettes. E-cigarette liquid (e-liquid) is mainly composed of propylene glycol (PG) and glycerol (Gly), and the aerosol generated by these devices primarily contains these two components. Thus, this study aimed to evaluate the effects of PG and Gly on human small airway epithelial cells (SAECs).

Methods

SAECs were exposed to PG or Gly, and cell proliferation, cell viability, lactate dehydrogenase (LDH) release, DNA damage, cell cycle, and apoptosis were evaluated. Additionally, SAECs derived from chronic obstructive pulmonary disease (COPD) patients (COPD-SAECs) were investigated.

Results

Exposure of SAECs to PG significantly inhibited proliferation (1%, PG, p = 0.021; 2–4% PG, p < 0.0001) and decreased cell viability (1–4% PG, p < 0.0001) in a concentration-dependent manner. Gly elicited similar effects but to a reduced degree as compared to the same concentration of PG. PG also increased LDH release in a concentration-dependent manner (3% PG, p = 0.0055; 4% PG, p < 0.0001), whereas Gly did not show a significant effect on LDH release. SAECs exposed to 4% PG contained more cells that were positive for phosphorylated histone H2AX (p < 0.0001), a marker of DNA damage, and an increased proportion of cells in the G1 phase (p < 0.0001) and increased p21 expression (p = 0.0005). Moreover, caspase 3/7-activated cells and cleaved poly (ADP-ribose) polymerase 1 expression were increased in SAECs exposed to 4% PG (p = 0.0054). Furthermore, comparing COPD-SAECs to SAECs without COPD in PG exposure, cell proliferation, cell viability, DNA damage and apoptosis were significantly greater in COPD-SAECs.

Conclusion

PG damaged SAECs more than Gly. In addition, COPD-SAECs were more susceptible to PG than SAECs without COPD. Usage of e-cigarettes may be harmful to the respiratory system, especially in patients with COPD.

Evaluating the Immediate Impact of Graphic Messages for Vaping Prevention among Black and Latino Adolescents: A Randomized Controlled Trial

The purpose of this pilot study was to assess the immediate impact of vaping prevention graphic messages on the susceptibility to future vaping among Black and Latino adolescents (ages 12 to 17). Graphic messages (available in English and Spanish) were developed using participatory research procedures with Black and Latino adolescents. Recruitment was conducted by a team of diverse, bilingual (English and Spanish), trained recruiters. Participants (n = 362) were randomized in a 1:1:1:1 schema to receive one of four graphic messages (health rewards, financial rewards, autonomy, and social norms). Overall, all graphic messages but one showed a slight decrease in the number of participants susceptible to future vaping, though none of these differences was statistically significant. The graphic message on health rewards decreased the number of participants susceptible to future vaping the most (55.7% vs. 50%, at pre- vs. post-viewing, p = 0.125), followed by the graphic messages on social norms and autonomy (55.1% vs. 52.8%, p = 0.687; 55.4% vs. 52.2%, p = 0.435; respectively). The graphic message on financial rewards increased the number of participants susceptible to future vaping slightly (52.7% vs. 53.8%, p = 1.00). Future research is needed to evaluate susceptibility to future vaping before and after exposure to different and/or repeated vaping prevention graphic messages.

On the toxicity of e-cigarettes consumption: Focus on pathological cellular mechanisms

Tobacco smoking remains without a doubt one of the leading causes of premature death worldwide. In combination with conventional protocols for smoking cessation, e-cigarettes have been proposed as a useful tool to quit smoking. Advertised as almost free of toxic effects, e-cigarettes have rapidly increased their popularity, becoming a sought-after device, especially among young people. Recently some health concerns about e-cigarette consumption are being raised. It is well known that they can release several toxic compounds, some of which are carcinogenic to humans, and emerging results are now outlining the risks related to the onset of respiratory and cardiovascular diseases and even cancer. The present review shows the emerging evidence about the role of technical components of the devices, the e-liquid composition as well as customization by consumers. The primary topics we discuss are the main toxicological aspects associated with e-cigarette consumption, focusing on the molecular pathways involved. Here it will be shown how exposure to e-cigarette aerosol induces stress/mitochondrial toxicity, DNA breaks/fragmentation following the same pathological pathways triggered by tobacco smoke, including the deregulation of molecular signalling axis associated with cancer progression and cell migration. Risk to fertility and pregnancy, as well as cardiovascular risk associated with e-cigarette use, have also been reported.

Facilitators and barriers for harm reduction after first use of novel nicotine delivery devices: a qualitative investigation of cigarette smokers

BACKGROUND

Novel nicotine delivery devices (NNDDs) are a safer alternative to combustible tobacco smoking. Understanding what factors can facilitate people who smoke to use NNDDs can inform intervention design and public health messaging. This study aims to explore the facilitators and barriers to NNDD use from the perspective of smokers without prior use, after trialling two NNDDs.

METHOD

UK adults who smoke combustible cigarettes (n = 11) were recruited from a larger quantitative study after trialling two NNDDs, an electronic cigarette and a heated tobacco product (order randomly allocated). Semi-structured interviews were conducted, transcribed and thematically analysed, using the COM-B model of behaviour and NVivo12 pro software.

RESULTS

Five main themes were identified: health knowledge, availability of and accessibility to NNDD products, cost, social acceptance, and NNDD use experience. There was curiosity and interest in the uptake and use of NNDDs, but the absence of centralised product information was identified as a barrier. Other themes were related to the design and functionality of the NNDD products. For example, the e-cigarette with its low maintenance was seen as easier to use than the heated tobacco product, which offered too short a single use duration and was described as 'cumbersome'. Throat discomfort and high anticipated cost were among additional barriers identified for both product types.

CONCLUSION

This study highlights the need for reliable objective information on the health effects of NNDDs compared with combustible cigarettes, which could facilitate their regular use. Product adjustment such as single use duration alignment with combustible cigarette smoking duration may encourage uptake. Interventions offering opportunity for experience of NNDD use and knowledge dissemination of NNDDs could increase motivation to adopt harm reducing behaviours as demonstrated in this study.

E-cigarettes to Augment Stop Smoking In-person Support and Treatment With Varenicline (E-ASSIST): A Pragmatic Randomized Controlled Trial

AIM

To examine whether, in adults receiving behavioral support, offering e-cigarettes together with varenicline helps more people stop smoking cigarettes than varenicline alone.

METHODS

A two-group, parallel arm, pragmatic randomized controlled trial was conducted in six English stop smoking services from 2019-2020. Adults enrolled onto a 12-week programme of in-person one-to-one behavioral smoking cessation support (N  =  92) were randomized to receive either (1) a nicotine e-cigarette starter kit alongside varenicline or (2) varenicline alone. The primary outcome was biochemically verified abstinence from cigarette smoking between weeks 9-to-12 post quit date, with those lost to follow-up considered not abstinent. The trial was stopped early due to COVID-19 restrictions and a varenicline recall (92/1266 participants used).

RESULTS

Nine-to-12-week smoking abstinence rates were 47.9% (23/48) in the e-cigarette-varenicline group compared with 31.8% (14/44) in the varenicline-only group, a 51% increase in abstinence among those offered e-cigarettes; however, the confidence interval (CI) was wide, including the possibility of no difference (risk ratio [RR] = 1.51, 95% CI = 0.91-2.64). The e-cigarette-varenicline group had 43% lower hazards of relapse from continuous abstinence than the varenicline-only group (hazards ratio [HR] = 0.57, 95% CI =  0.34-0.96). Attendance for 12 weeks was higher in the e-cigarette-varenicline than varenicline-only group (54.2% vs. 36.4%; RR = 1.49, 95% CI = 0.95-2.47), but similar proportions of participants in both groups used varenicline daily for ≥8 weeks after quitting (22.9% versus 22.7%; RR = 1.01, 95% CI = 0.47-2.20). Estimates were too imprecise to determine how adverse events differed by group.

CONCLUSION

Tentative evidence suggests that offering e-cigarettes alongside varenicline to people receiving behavioral support may be more effective for smoking cessation than varenicline alone.

IMPLICATIONS

Offering e-cigarettes to people quitting smoking with varenicline may help them remain abstinent from cigarettes, but the evidence is tentative because our sample size was smaller than planned-caused by Coronavirus Disease 2019 (COVID-19) restrictions and a manufacturing recall. This meant our effect estimates were imprecise, and additional evidence is needed to confirm that providing e-cigarettes and varenicline together helps more people remain abstinent than varenicline alone.

Proactive and Reactive Recruitment of Black and Latino Adolescents in a Vaping Prevention Randomized Controlled Trial

The purpose of this study was to assesses the effectiveness of proactive and reactive methods in the recruitment of Black and Latino adolescents into a vaping-prevention randomized controlled trial (RCT). This study also assessed the characteristics of study participants by recruitment method. Proactive recruitment strategies included study presentations at community-based events (e.g., festivals, health fairs), school-based events (e.g., back-to-school events, after-school programs), and recreational centers (e.g., fitness centers, malls). Reactive recruitment strategies included study advertisements via social media (e.g., Facebook posts shared by local community-based organizations), word of mouth, and an academic-based research hub. Using proactive and reactive methods, in a 4-month period, 362 Black and Latino adolescents were successfully enrolled into the RCT. Compared to the proactive method, adolescents screened reactively were equally likely to be eligible but significantly more likely to enroll in the study. However, both proactive and reactive strategies made notable contributions to the overall recruitment effort. Moreover, proactive and reactive methods attracted adolescents with different characteristics (e.g., age, gender, sexual orientation, etc.). These findings suggest that both proactive and reactive recruitment strategies should be implemented for studies interested in recruiting a diverse sample of Black and Latino adolescents.

Biomarkers of Exposure and Biomarkers of Potential Harm in Adult Smokers Who Switch to e-Vapor Products Relative to Cigarette Smoking in a 24-week, Randomized, Clinical Trial

INTRODUCTION

Long-term health effects of e-vapor products (EVPs) are not well-established. We compared biomarkers of exposure (BoE) to select harmful and potentially harmful constituents and biomarkers of potential harm (BoPH) in adult smokers who switched to EVPs versus continued smoking for 24 weeks.

METHODS

Adult smokers (n = 450, >10 cigarettes per day for ≥10 years) were randomly assigned to continue smoking (control) or switch to one of two cartridge-based EVPs (test 1: classic; test 2: menthol, 4% nicotine). BoE and BoPH were measured at baseline and 12 weeks. The results presented here are from a subset of 150 control and EVP subjects (switchers with exhaled carbon monoxide <8 ppm and <10% baseline cigarettes per day) followed for 24 total weeks.

RESULTS

Total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and carboxyhemoglobin were significantly reduced (p < .0001) in tests 1 and 2 at 24 weeks. Urinary nicotine equivalents were not statistically significantly different between the control and EVP groups. At week 24, statistically significant reductions (p < .05) were observed for white blood cell counts, 11-dehydrothromboxane β2, and sICAM in both test groups, and there were several significant changes in measures of pulmonary function. High-density lipoprotein cholesterol and 8-epi-prostaglandin-F2α were directionally favorable in both EVP groups versus control.

CONCLUSIONS

We demonstrate that significant reductions of selected harmful and potentially harmful constituents in EVP aerosol results in significant reductions in BoEs and favorable changes in BoPHs after switching to EVPs for 24 weeks. These changes approached those reported for smoking cessation, suggesting that switching to exclusive use of the EVPs may be less harmful than continuing smoking.

IMPLICATIONS

Cigarette smoking causes serious diseases. Switching from cigarettes to a noncombustible product is a potential harm reduction pathway for adult smokers unable or unwilling to quit. Long-term health effects of e-vapor products (EVPs) compared with continued smoking have not been extensively studied. We present biomarker of exposure evidence on select harmful and potentially harmful constituents and biomarkers of potential harm related to inflammation and oxidative stress in adult smokers switching to two EVPs. This study demonstrates significant reductions in biomarkers of exposure (except for nicotine) accompanied with favorable changes in various biomarkers of potential harm, including pulmonary function. The totality of evidence suggests that exclusive EVP use may present lower health risks compared with smoking cigarettes.

Increased acrolein-DNA adducts in buccal brushings of e-cigarette users

DNA adducts are central in the mechanism of carcinogenesis by genotoxic agents. We compared levels of a DNA adduct of acrolein, a genotoxic carcinogen found in e-cigarette vapor, in oral cell DNA of e-cigarette users and non-users of any tobacco or nicotine product. e-Cigarette users and non-users visited our clinic once monthly for 6 months, and oral brushings and urine samples were collected. For this study, we analyzed oral cell DNA adducts from three monthly visits in e-cigarette users and non-users as confirmed by urinary cyanoethyl mercapturic acid and total nicotine equivalents. DNA was isolated from the oral brushings and analyzed by a validated liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry method for the acrolein DNA adduct 8R/S-3-(2'-deoxyribos-1'-yl)-5,6,7,8-tetrahydro-8-hydroxypyrimido[1,2-a]purine-10-(3H)-one (γ-OH-Acr-dGuo). The median value of this DNA adduct in the e-cigarette users was 179 fmol/µmol dGuo (range 5.0 - 793 fmol/µmol dGuo) while that for non-users was 21.0 fmol/µmol dGuo (range 5.0 - 539 fmol/µmol dGuo), P = 0.001. These results demonstrate for the first time that e-cigarette users have elevated levels of a carcinogen-DNA adduct in their oral cells.

A randomised, crossover, clinical study to assess nicotine pharmacokinetics and subjective effects of the BIDI® stick ENDS compared with combustible cigarettes and a comparator ENDS in adult smokers

BACKGROUND

Nicotine pharmacokinetic assessments of electronic nicotine delivery systems (ENDS) are crucial to understand their ability to provide an alternative to cigarette smoking. Subjective effects data also strongly contribute to this understanding. The BIDI® Stick is a disposable ENDS product which contains 59 mg/ml nicotine benzoate salt and various flavours.

METHODS

In this study, we assessed nicotine pharmacokinetics and subjective effects of 6 flavour variants of BIDI® Stick ENDS in adult smokers, compared to cigarettes and a comparator ENDS product. During each of eight study visits, 18 volunteer smoker subjects randomly used one of either their usual brand (UB) of cigarette, a BIDI® Stick ENDS, or a comparator ENDS (JUUL 59 mg/ml nicotine with Virginia Tobacco flavour), during both controlled (10 puffs, 30 s apart) and ad libitum (60 min) puffing sessions. Blood samples were collected at various time points and subjective effects questionnaires were administered.

RESULTS

Mean [SD] plasma nicotine Cmax 0-120 was not significantly different between BIDI® Stick ENDS with any flavour (range 15.3 [9.90] ng/ml for BIDI® Stick Winter to 17.6 [9.00] ng/ml for BIDI® Stick Classic) and UB cigarettes (16.2 [9.17] ng/ml). Mean [SD] AUC0-120 (range 569.7 [327.29] to 628.6 [408.99]  min*ng/ml for BIDI® Stick ENDS and 747.1 [325.48]  min*ng/ml for UB cigarettes) and median Tmax 0-120 (range 5-7 min for all BIDI® Stick ENDS and UB cigarettes) values were also not significantly different between BIDI® Stick ENDS and UB cigarettes, while subjective effects measures were also similar between BIDI® Stick ENDS and UB cigarettes. Mean [SD] plasma nicotine Cmax 0-120, AUC0-120, and median Tmax 0-120 were 6.8 [4.13] ng/ml, 243.6 [179.04] min*ng/ml, and 5 min, respectively, for JUUL ENDS. These values were significantly different compared with those for all BIDI® Stick ENDS and UB cigarettes for both Cmax 0-120 and AUC0-120 but not for Tmax 0-120.

CONCLUSIONS

BIDI® Stick ENDS delivered nicotine to users comparably to their UB combustible cigarette and higher than JUUL ENDS, and also elicited similar subjective effects such as satisfaction and relief. Thus, the BIDI® Stick ENDS may be a satisfying alternative to cigarettes among current smokers and may support their transitioning away from cigarette smoking.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier number NCT05072925).

Serum Concentrations of Cotinine and Trans-3'-Hydroxycotinine in US Adults: Results From Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health Study

INTRODUCTION

The Population Assessment of Tobacco and Health (PATH) Study is a nationally representative cohort of tobacco product users and nonusers. The study's main purpose is to obtain longitudinal epidemiologic data on tobacco use and exposure among the US population.

AIMS AND METHODS

Nicotine biomarkers-cotinine (COT) and trans-3'-hydroxycotinine (HCT)-were measured in blood samples collected from adult daily tobacco users and nonusers during Wave 1 of the PATH Study (2013-2014; n = 5012; one sample per participant). Participants' tobacco product use and exposure to secondhand smoke were categorized based on questionnaire responses. Nonusers were subdivided into never users and recent former users. Daily tobacco users were classified into seven tobacco product use categories: exclusive users of cigarette, smokeless tobacco, electronic cigarette, cigar, pipe, and hookah, as well as polyusers. We calculated sample-weighted geometric mean (GM) concentrations of cotinine, HCT, and the nicotine metabolite ratio (NMR) and evaluated their associations with tobacco use with adjustment for potential confounders.

RESULTS

The GMs (95% confidence intervals) of COT and HCT concentrations for daily tobacco users were 196 (184 to 208) and 72.5 (67.8 to 77.4) ng/mL, and for nonusers they were 0.033 (0.028 to 0.037) and 0.021 (0.018 to 0.023) ng/mL. Exclusive smokeless tobacco users had the highest COT concentrations of all user groups examined. The GM NMR in daily users was 0.339 (95% confidence interval: 0.330 to 0.350).

CONCLUSIONS

These nationally representative estimates of serum nicotine biomarkers could be the basis for reference ranges characterizing nicotine exposure for daily tobacco users and nonusers in the US adult population.

IMPLICATIONS

This report summarizes the serum nicotine biomarker measurements in Wave 1 of the PATH Study. We are reporting the first estimates of HCT in serum for daily tobacco users and nonusers in the noninstitutionalized, civilian US adult population; the first nationally representative serum COT estimates for daily exclusive users of different tobacco products and daily polyusers; and the first nationally representative estimate of the serum NMR in daily tobacco users by age, race/ethnicity, and sex.

E-Cigarette Aerosol Deposition and Disposition of [11C]Nicotine Using Positron Emission Tomography: A Comparison of Nicotine Uptake in Lungs and Brain Using Two Different Nicotine Formulations

Smoking is a cause of serious disease in smokers. Electronic cigarettes, delivering aerosolized nicotine, offer adult smokers a potentially less harmful alternative to combustible cigarettes. This explorative PET/CT study investigated the distribution and deposition of inhaled [¹¹C]nicotine using the myblu^TM e-cigarette with two nicotine formulations, freebase and lactate salt. Fifteen healthy adult smokers participated in the two-part study to assess the distribution and accumulation of [¹¹C]nicotine in the respiratory pathways and brain. Time-activity data for the respiratory pathways, lungs, oesophagus and brain were derived. 31–36% of both inhaled tracer formulations accumulated in the lung within 15–35 s. [¹¹C]Nicotine_freebase exhibited higher uptake and deposition in the upper respiratory pathways. For [¹¹C]nicotine_lactate, brain deposition peaked at 4–5%, with an earlier peak and a steeper decline. A different kinetic profile was obtained for [¹¹C]nicotine_lactate with lower tracer uptake and accumulation in the upper respiratory pathways and an earlier peak and a steeper decline in lung and brain. Using nicotine lactate formulations in e-cigarettes may thus contribute to greater adult smoker acceptance and satisfaction compared to freebase formulations, potentially aiding a transition from combustible cigarettes and an acceleration of tobacco harm reduction initiatives.

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).

Instigators of COVID-19 in Immune Cells Are Increased in Tobacco Cigarette Smokers and Electronic Cigarette Vapers Compared With Nonsmokers

INTRODUCTION

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic, gains entry into the host cell when its Spike protein is cleaved by host proteases TMPRSS2 and furin, thereby markedly increasing viral affinity for its receptor, angiotensin-converting enzyme-2 (ACE2). In rodent and diseased human lungs, tobacco cigarette (TCIG) smoke increases ACE2, but the effect of electronic cigarette vaping (ECIG) is unknown. It is unknown whether nicotine (in both TCIGs and ECIGs) or non-nicotine constituents unique to TCIG smoke increase expression of key proteins in COVID-19 pathogenesis.

METHODS

Immune (CD45+) cells collected before the pandemic in otherwise healthy young people, including TCIG smokers (n = 9), ECIG vapers (n = 12), or nonsmokers (NS) (n = 12), were studied. Using flow cytometry, expression of key proteins in COVID-19 pathogenesis were compared among these groups.

RESULTS

TCIG smokers and ECIG vapers had similar smoking or vaping burdens as indicated by similar plasma cotinine levels. TCIG smokers compared with NS had a significantly increased percentage of cells that were positive for ACE2 (10-fold, p < .001), TMPRSS2 (5-fold, p < .001), and ADAM17 (2.5-fold, p < .001). Additionally, the mean fluorescence intensity (MFI) consistently showed greater mean ACE2 (2.2-fold, p < .001), TMPRSS2 (1.5-fold, p < .001), furin (1.1-fold, p < .05), and ADAM17 (2-fold, p < .001) in TCIG smokers compared with NS. In ECIG vapers, furin MFI was increased (1.15-fold, p < .05) and TMPRSS2 MFI tended to be increased (1.1-fold, p = .077) compared with NS.

CONCLUSIONS

The finding that key instigators of COVID-19 infection are lower in ECIG vapers compared with TCIG smokers is intriguing and warrants additional investigation to determine if switching to ECIGs is an effective harm reduction strategy. However, the trend toward increased proteases in ECIG vapers remains concerning.

IMPLICATIONS

(1) This is the first human study to report a marked increase in proteins critical for COVID-19 infection, including ACE2, TMPRSS2, and ADAM17, in immune cells from healthy tobacco cigarette smokers without lung disease compared with e-cigarette vapers and nonsmokers. (2) These findings warrant additional investigation to determine whether switching to electronic cigarettes may be an effective harm reduction strategy in smokers addicted to nicotine who are unable or unwilling to quit. (3) The increase in proteases in electronic cigarette vapers remains concerning.

Pilot study to determine differences in breath odour between cigarette and e-cigarette consumers

Cigarette smoke is known to influence breath odour, but the effect of e-cigarettes is unknown. In this pilot study, we aimed to determine differences in breath odour between cigarette smokers (CSs) and e-cigarette consumers (ECs) in 33 healthy subjects: 11 CSs, 11 ECs and 11 non-smokers (NSs). Breath was sampled at baseline and following product use (CSs and ECs) or a waiting period (NSs) by eight trained odour judges using a six-point smoke intensity scale and a nine-point hedonic scale. We observed a statistically significant difference between CSs and ECs. Smoke intensity values were significantly higher in CSs than ECs and NSs, which were comparable both at baseline and after product use. In addition, hedonic values for CSs were significantly lower than both NSs and ECs after product use. These acute results indicate that cigarette and e-cigarette use results in significantly different breath. ECs breath has a reduced smoke odour and more pleasant aroma than CSs, and is comparable to NSs. This suggests there may be cosmetic benefits for CSs who quit smoking or switch to exclusive use of ECs. Further studies are required to understand the long-term effects of e-cigarette use on breath odour.

Intentions and Attempts to Quit JUUL E-Cigarette Use: The Role of Perceived Harm and Addiction

Introduction

Research on electronic cigarette (e-cigarette) quit intentions and attempts is limited despite the potential health benefits of quitting, especially for long-term users. The current study aimed to investigate perceptions of harm and addictiveness and tobacco use characteristics associated with quit variables among users of a popular e-cigarette brand, JUUL.

Methods

We surveyed 301 US adult JUUL users on their tobacco use characteristics, perceptions of JUUL harm and addictiveness, and quit variables at 3 time points, from July 2019 to April 2020. We used logistic regression models to assess demographic characteristics, smoking characteristics, and perceptions of JUUL harm and addictiveness as correlates of e-cigarette quit intentions, attempts, importance, and confidence.

Results

Twenty-three percent of the sample had intentions to quit using JUUL within the year, and 22.6% reported making a lifetime quit attempt. The average rating of quit importance was 4.1 and quit confidence was 5.8 on a Likert scale of 1 to 10. More than 90% of the sample indicated that JUUL was at least moderately addictive, whereas less than one-quarter indicated that JUUL was as harmful or more harmful than smoking. Higher levels of perceived JUUL addictiveness were associated with more quit intentions, attempts, and importance. Higher levels of perceived JUUL harm compared with smoking were associated with more quit importance.

Conclusion

Our findings suggest that a small proportion of adult JUUL users are interested in quitting. Self-reported perceptions of JUUL’s addiction potential may be related to more quit attempts. Findings highlight the need for evidence-based information on e-cigarette addictiveness and effective strategies for cessation.

Preferred flavors and tobacco use patterns in adult dual users of cigarettes and ENDS

OBJECTIVES

This study examined how adult dual users of cigarettes and electronic nicotine delivery system (ENDS) flavor preference varied by demographics, tobacco history, motives, and expectancies for ENDS, and how ENDS flavor preference was associated with changes in cigarette and ENDS use over 12 months.

METHODS

Data come from the baseline and 12-month waves of an observational study of adult dual cigarette and ENDS users (N = 406). Flavor preferences were grouped into 4 categories: tobacco (12.6%), menthol/mint (34.7%), sweet (44.8%), and other (7.9%).

RESULTS

Users of sweet-flavored ENDS were significantly younger than those who used tobacco- or menthol flavors. Black dual users were significantly more likely than other racial groups to use menthol and less likely to use sweet flavors. Dual users who preferred sweet flavors smoked cigarettes on fewer days than those who preferred tobacco and menthol flavors, were less cigarette dependent, more strongly endorsed boredom reduction expectancies and motives related to taste and sensory experience and were more likely to stop smoking by 12 months.

CONCLUSIONS

Dual users of cigarettes and ENDS who preferred sweet flavored ENDS differed in demographics, tobacco history, motives, expectancies, and smoking changes. Findings have implications for interventions and regulations.

Changes in Biomarkers of Tobacco Exposure among Cigarette Smokers Transitioning to ENDS Use: The Population Assessment of Tobacco and Health Study, 2013-2015

Limited data are available for how biomarkers of tobacco exposure (BOE) change when cigarette smokers transition to using electronic nicotine delivery systems (ENDS). Using biomarker data from Waves 1 (2013-2014) and 2 (2014-2015) of the PATH Study, we examined how mean BOE concentrations, including metabolites of nicotine, tobacco-specific nitrosamines (TSNA), polycyclic aromatic hydrocarbons (PAH), and volatile organic compounds (VOC) and metals, changed when 2475 adult smokers transitioned to using ENDS or quit tobacco products. Exclusive smokers who transitioned to dual use had a significant decrease in NNAL (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol), but not nicotine metabolites, most PAHs, metals, or VOCs. Exclusive smokers who became dual users had significant reductions in total nicotine equivalents, NNAL, and 2CyEMA (acrylonitrile metabolite), but only in those who reduced cigarettes per day (CPD) by >=50%. Smokers who transitioned to exclusive ENDS use had significant reductions in most TSNAs, PAHs, and VOCs; however, nicotine metabolites did not decrease in dual users who became exclusive ENDS users. Smokers who quit tobacco use had significant decreases in nicotine metabolites, all TSNAs, most PAHs, and most VOCs. Cigarette smokers who became dual users did not experience significant reductions in most BOEs. Reductions were impacted by changes in CPD. However, transitioning from smoking to no tobacco or exclusive ENDS use was associated with reduced exposure to most BOEs measured. Future analyses could incorporate additional waves of PATH data and examine changes in biomarker exposure by ENDS device type and CPD.

Heart Disease and Stroke Statistics-2022 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2022 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population and an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, and the global burden of cardiovascular disease and healthy life expectancy.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Changes in Cigarette Smoking and Vaping in Response to the COVID-19 Pandemic in the UK: Findings from Baseline and 12-Month Follow up of HEBECO Study

This study investigated UK adults' changes in cigarette smoking and vaping during the COVID-19 pandemic and factors associated with any changes. Data were from an online longitudinal study. A self-selected sample (n = 332) of 228 smokers and 155 vapers (51 participants were both smokers and vapers) completed 5 surveys between April 2020 and June 2021. Participants self-reported data on sociodemographics, COVID-19-related, and smoking/vaping characteristics. During the 12 months of observations, among smokers, 45% self-reported a quit attempt (27.5% due to COVID-19-related reasons) since the onset of COVID-19 pandemic and the quit rate was 17.5%. At 12 months, 35.1% of continuing smokers (n = 174) reported smoking less and 37.9% the same, while 27.0% reported an increase in the number of cigarettes smoked/day. Among vapers, 25.0% self-reported a quit attempt (16.1% due to COVID-19-related reasons) and the quit rate was 18.1%. At 12 months, 47.7% of continuing vapers (n = 109) reported no change in the frequency of vaping/hour, while a similar proportion reported vaping less (27.5%) and more (24.8%). Motivation to quit smoking and being younger were associated with making a smoking quit attempt and smoking cessation. Being a cigarette smoker was associated with vaping cessation. Among a self-selected sample, COVID-19 stimulated more interest in reducing or quitting cigarette smoking than vaping.

Heated tobacco products for smoking cessation and reducing smoking prevalence

BACKGROUND

Heated tobacco products (HTPs) are designed to heat tobacco to a high enough temperature to release aerosol, without burning it or producing smoke. They differ from e-cigarettes because they heat tobacco leaf/sheet rather than a liquid. Companies who make HTPs claim they produce fewer harmful chemicals than conventional cigarettes. Some people report stopping smoking cigarettes entirely by switching to using HTPs, so clinicians need to know whether they are effective for this purpose and relatively safe. Also, to regulate HTPs appropriately, policymakers should understand their impact on health and on cigarette smoking prevalence.

OBJECTIVES

To evaluate the effectiveness and safety of HTPs for smoking cessation and the impact of HTPs on smoking prevalence.  SEARCH METHODS: We searched the Cochrane Tobacco Addiction Group's Specialised Register, CENTRAL, MEDLINE, and six other databases for relevant records to January 2021, together with reference-checking and contact with study authors and relevant groups.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people who smoked cigarettes were randomised to switch to exclusive HTP use or a control condition. Eligible outcomes were smoking cessation, adverse events, and selected biomarkers.  RCTs conducted in clinic or in an ambulatory setting were deemed eligible when assessing safety, including those randomising participants to exclusively use HTPs, smoke cigarettes, or attempt abstinence from all tobacco. Time-series studies were also eligible for inclusion if they examined the population-level impact of heated tobacco on smoking prevalence or cigarette sales as an indirect measure.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking at the longest follow-up point available, adverse events, serious adverse events, and changes in smoking prevalence or cigarette sales. Other outcomes included biomarkers of harm and exposure to toxicants/carcinogens (e.g. NNAL and carboxyhaemoglobin (COHb)). We used a random-effects Mantel-Haenszel model to calculate risk ratios (RR) with 95% confidence intervals (CIs) for dichotomous outcomes. For continuous outcomes, we calculated mean differences on the log-transformed scale (LMD) with 95% CIs. We pooled data across studies using meta-analysis where possible.

MAIN RESULTS

We included 13 completed studies, of which 11 were RCTs assessing safety (2666 participants) and two were time-series studies. We judged eight RCTs to be at unclear risk of bias and three at high risk. All RCTs were funded by tobacco companies. Median length of follow-up was 13 weeks. No studies reported smoking cessation outcomes.  There was insufficient evidence for a difference in risk of adverse events between smokers randomised to switch to heated tobacco or continue smoking cigarettes, limited by imprecision and risk of bias (RR 1.03, 95% CI 0.92 to 1.15; I2 = 0%; 6 studies, 1713 participants). There was insufficient evidence to determine whether risk of serious adverse events differed between groups due to very serious imprecision and risk of bias (RR 0.79, 95% CI 0.33 to 1.94; I2 = 0%; 4 studies, 1472 participants). There was moderate-certainty evidence for lower NNAL and COHb at follow-up in heated tobacco than cigarette smoking groups, limited by risk of bias (NNAL: LMD -0.81, 95% CI -1.07 to -0.55; I2 = 92%; 10 studies, 1959 participants; COHb: LMD -0.74, 95% CI -0.92 to -0.52; I2 = 96%; 9 studies, 1807 participants). Evidence for additional biomarkers of exposure are reported in the main body of the review. There was insufficient evidence for a difference in risk of adverse events in smokers randomised to switch to heated tobacco or attempt abstinence from all tobacco, limited by risk of bias and imprecision (RR 1.12, 95% CI 0.86 to 1.46; I2 = 0%; 2 studies, 237 participants). Five studies reported that no serious adverse events occurred in either group (533 participants). There was moderate-certainty evidence, limited by risk of bias, that urine concentrations of NNAL at follow-up were higher in the heated tobacco use compared with abstinence group (LMD 0.50, 95% CI 0.34 to 0.66; I2 = 0%; 5 studies, 382 participants). In addition, there was very low-certainty evidence, limited by risk of bias, inconsistency, and imprecision, for higher COHb in the heated tobacco use compared with abstinence group for intention-to-treat analyses (LMD 0.69, 95% CI 0.07 to 1.31; 3 studies, 212 participants), but lower COHb in per-protocol analyses (LMD -0.32, 95% CI -1.04 to 0.39; 2 studies, 170 participants). Evidence concerning additional biomarkers is reported in the main body of the review. Data from two time-series studies showed that the rate of decline in cigarette sales accelerated following the introduction of heated tobacco to market in Japan. This evidence was of very low-certainty as there was risk of bias, including possible confounding, and cigarette sales are an indirect measure of smoking prevalence.

AUTHORS' CONCLUSIONS

No studies reported on cigarette smoking cessation, so the effectiveness of heated tobacco for this purpose remains uncertain. There was insufficient evidence for differences in risk of adverse or serious adverse events between people randomised to switch to heated tobacco, smoke cigarettes, or attempt tobacco abstinence in the short-term. There was moderate-certainty evidence that heated tobacco users have lower exposure to toxicants/carcinogens than cigarette smokers and very low- to moderate-certainty evidence of higher exposure than those attempting abstinence from  all tobacco. Independently funded research on the effectiveness and safety of HTPs is needed.  The rate of decline in cigarette sales accelerated after the introduction of heated tobacco to market in Japan but, as data were observational, it is possible other factors caused these changes. Moreover, falls in cigarette sales may not translate to declining smoking prevalence, and changes in Japan may not generalise elsewhere. To clarify the impact of rising heated tobacco use on smoking prevalence, there is a need for time-series studies that examine this association.

DNA damage, DNA repair and carcinogenicity: Tobacco smoke versus electronic cigarette aerosol

The allure of tobacco smoking is linked to the instant gratification provided by inhaled nicotine. Unfortunately, tobacco curing and burning generates many mutagens including more than 70 carcinogens. There are two types of mutagens and carcinogens in tobacco smoke (TS): direct DNA damaging carcinogens and procarcinogens, which require metabolic activation to become DNA damaging. Recent studies provide three new insights on TS-induced DNA damage. First, two major types of TS DNA damage are induced by direct carcinogen aldehydes, cyclic-1,N2-hydroxy-deoxyguanosine (γ-OH-PdG) and α-methyl-1, N2-γ-OH-PdG, rather than by the procarcinogens, polycyclic aromatic hydrocarbons and aromatic amines. Second, TS reduces DNA repair proteins and activity levels. TS aldehydes also prevent procarcinogen activation. Based on these findings, we propose that aldehydes are major sources of TS induce DNA damage and a driving force for carcinogenesis. E-cigarettes (E-cigs) are designed to deliver nicotine in an aerosol state, without burning tobacco. E-cigarette aerosols (ECAs) contain nicotine, propylene glycol and vegetable glycerin. ECAs induce O6-methyl-deoxyguanosines (O6-medG) and cyclic γ-hydroxy-1,N2--propano-dG (γ-OH-PdG) in mouse lung, heart and bladder tissues and causes a reduction of DNA repair proteins and activity in lungs. Nicotine and nicotine-derived nitrosamine ketone (NNK) induce the same types of DNA adducts and cause DNA repair inhibition in human cells. After long-term exposure, ECAs induce lung adenocarcinoma and bladder urothelial hyperplasia in mice. We propose that E-cig nicotine can be nitrosated in mouse and human cells becoming nitrosamines, thereby causing two carcinogenic effects, induction of DNA damage and inhibition of DNA repair, and that ECA is carcinogenic in mice. Thus, this article reviews the newest literature on DNA adducts and DNA repair inhibition induced by nicotine and ECAs in mice and cultured human cells, and provides insights into ECA carcinogenicity in mice.

Urinary volatomic profile of traditional tobacco smokers and electronic cigarettes users as a strategy to unveil potential health issues

Many harmful and potentially harmful constituents are present in tobacco products. Cigarette smoke is known to cause different forms of cancer and trigger the development of chronic diseases. In the last decade, electronic cigarettes have emerged as a healthier alternative associated to less harmful effects in comparison to traditional tobacco. However, the lack of standardization of electronic cigarettes products makes it difficult to establish and compare the real effects on health of products from different manufacturers. To better understand the impact of smoking and vaping, the volatomic composition of urine samples from traditional tobacco smokers and electronic cigarette users was established and compared with nonsmokers (control group), using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry. A total of 45 urinary volatile organic metabolites belonging to different chemical families were identified in the urine of the studied groups. Benzene derivatives, terpenes, and aromatics were the chemical families that contributed the most to the urinary profile of smokers. The vapers urinary volatomic pattern was also dominated by terpenes and aromatics, in addition to alcohols. The orthogonal partial least squares-discriminant analysis of the data obtained indicated that the urinary profile of vapers is more closely related to the control group, reinforcing the hypothesis of the lowest harmfulness of electronic cigarettes. Further studies recruiting a higher number of subjects are therefore necessary to consolidate the data obtained.

Inverse association between blood ethylene oxide levels and obesity in the general population: NHANES 2013-2016

BACKGROUND

Ethylene oxide (EO) has been shown to associate with increased cardiovascular risk. This study aimed to explore the relationship and its meditating factors between EO exposure and the major cardiovascular risk factor of obesity among the general adult population.

METHODS

Cross-sectional data of 3,220 participants from National Health and Nutritional Examination Survey (NHANES) 2013-2016 were enrolled. Obesity was defined as body mass index (BMI) ≥30 kg/m², and abdominal obesity was defined as waist circumference (WC) ≥102 cm in men and ≥88 cm in women. The association among hemoglobin adduct of EO (HbEO), inflammatory biomarkers, and obesity was evaluated using restricted cubic splines and the multivariable linear regression model. Mediation analysis was used to further assess their association.

RESULTS

The increased quartiles of HbEO were inversely associated with BMI and WC [Q1 vs. Q4, BMI: β = -2.98 (-3.74, -2.22), WC: β = -6.50 (-8.60, -4.39); all p for trend < 0.05], and were inversely associated with obesity after full adjustment [obesity: OR = 0.43 (0.31, 0.58), abdominal obesity: OR = 0.42 (0.27, 0.65); all p for trend < 0.05]. The levels of alkaline phosphatase, white blood cells, lymphocytes, and neutrophils were also positively associated with BMI and WC (all p < 0.05). Mediation analysis showed that exposure of EO not only had a negative direct effect on BMI and WC, but also generated an inverse indirect effect.

CONCLUSIONS

Current findings showed an inverse association between HbEO and obesity, and suggested that systemic inflammation may not be their only mediator. Additional research is required to explore the underlying link of EO and system metabolism.

Changes in dependence, withdrawal, and craving among adult smokers who switch to nicotine salt pod-based e-cigarettes

BACKGROUND AND AIMS

For electronic cigarettes (e-cigarettes) to be a viable substitute for combustible cigarettes, it is likely that they must be rewarding enough for regular use, indicated by factors such as craving and dependence, important aspects of reinforcement. This study aimed to understand short-term changes in measures of nicotine dependence between groups differing by use trajectory in a switching trial, and within group changes of these measures.

DESIGN

Secondary data analysis of one arm of an e-cigarette randomized clinical trial.

SETTING

San Diego, California and Kansas City, Missouri, United States.

PARTICIPANTS

114 African American (n = 60) and Latinx (n = 54) smokers (58.8% male) attempting to switch to nicotine salt pod system (NSPS) e-cigarettes in a 6-week trial.

MEASUREMENTS

At week 6, participants were classified by use trajectory: exclusive smokers (n = 16), exclusive e-cigarette (n = 32), or dual users (n = 66). E-cigarette, cigarette, and total nicotine dependence (cigarette + e-cigarette), use patterns, cigarette craving and nicotine withdrawal, and cotinine were assessed at baseline and week 6 using standard measures.

FINDINGS

In between group comparisons, exclusive e-cigarette and dual users showed greater reductions in cigarette dependence (e-cigarette: -32.38, 95% CI = -37.7,-27.1; dual: -18.48, 95% CI = -22.2,-14.7), withdrawal (e-cigarette: -6.25, 95% CI = -8.52,-3.98; dual: -3.18, 95% CI = -5.02,-1.34), craving (e-cigarette: -11.44, 95% CI = -14.2,8.7; dual: -9.59, 95% CI = -11.6,-7.59), and cigarettes per day (CPD; e-cigarette: -11.19, 95% CI = -13.1,-9.27; dual: -9.39, 95% CI = -11.3, -7.52) compared with exclusive smokers. In within group analyses, e-cigarette and dual users showed reductions in craving and withdrawal from baseline to week 6. Exclusive e-cigarette and dual users, maintained cotinine levels (all Ps > 0.05) and showed reductions in CPD and cigarette dependence (all Ps < 0.01). Findings were inconclusive regarding changes in total nicotine dependence from baseline to week 6 among exclusive e-cigarette users (P = 0.123). Dual users showed increased total nicotine dependence (P < 0.001) and smokers showed decreased total dependence (P = 0.004).

CONCLUSIONS

Smokers who switch to nicotine salt pod system e-cigarettes maintain their nicotine levels and transfer their dependence, suggesting that nicotine salt pod system e-cigarettes have a similar reinforcement potential to cigarettes and facilitate switching.

A novel clinical method to measure skin staining reveals activation of skin damage pathways by cigarette smoke

BACKGROUND

Long-term use of cigarettes can result in localised staining and aging of smokers' skin. The use of tobacco heating products (THPs) and electronic cigarettes (ECs) has grown on a global scale; however, the long-term effect of these products' aerosols on consumers' skin is unknown. This pilot clinical study aimed to determine whether THP or EC aerosol exposure results in skin staining or activation of biomarkers associated with oxidative stress.

MATERIALS AND METHODS

Eight areas were identified on the backs of 10 subjects. Two areas were used for air control, and two areas exposed to 32-puffs of cigarette smoke (CS), THP or EC aerosols, which were delivered to the skin using a 3-cm diameter exposure chamber and smoke engine. Skin colour was measured using a Chromameter. Squalene (SQ), SQ monohydroperoxide (SQOOH) and malondialdehyde (MDA) levels were measured in sebum samples by mass spectrometry and catalase colorimetry.

RESULTS

CS exposure significantly increased skin staining, SQOOH and MDA levels and SQOOH/SQ ratio. THP and EC values were significantly lower than CS; EC values being comparable to air control. THP values were comparable to EC and air control at all endpoints, apart from skin staining. SQ and catalase levels did not change with exposure.

CONCLUSIONS

CS stained skin and activated pathways known to be associated with skin damage. THPs and ECs produced significantly lower values, suggesting they could offer hygiene and cosmetic benefits for consumers who switch exclusively from smoking cigarettes. Further studies are required to assess longer-term effects of ECs and THPs on skin function.

Tobacco-use behavior and toxicant exposure among current dual users of electronic cigarettes and tobacco cigarettes

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

Smoking and vaping patterns during pregnancy and the postpartum: A longitudinal UK cohort survey

INTRODUCTION

There is limited information about longitudinal patterns of vaping during pregnancy and the postpartum. We describe the prevalence, frequency, and reasons for vaping throughout pregnancy and postpartum. We also describe temporal patterns in pregnant women's vaping.

METHODS

A longitudinal cohort study across England and Scotland, with questionnaires in early pregnancy (8-24 weeks gestation), late pregnancy (34-38 weeks) and 3 months postpartum. A total of 750 women, aged 16 years or over, who were either current smokers, vapers or had smoked in the 3 months before pregnancy, were recruited between June and November 2017.

RESULTS

Vaping prevalence was 15.9% (n = 119/750) in early pregnancy: 12.4% (n = 93/750) were dual users and 3.5% (n = 26/750) exclusive vapers. Late pregnancy vaping prevalence was 17.8% (n = 68/383): 12.5% (n = 48/383) were dual users and 5.2% (n = 20/383) exclusive vapers. Postpartum vaping prevalence was 23.1% (n = 95/411): 14.6% (n = 60/411) were dual users and 8.5% (n = 35/411) exclusive vapers. The most frequently reported reason to vape among all vapers was to quit smoking. A total of 316 women completed all three surveys: 2.6% (n = 8/316) were exclusive vapers in early pregnancy with most remaining exclusive vapers postpartum (n = 6/8, 75%). Of the 11.5% (n = 35/316) dual users in early pregnancy, 31.4% (n = 11/35) were exclusive smokers by the postpartum.

CONCLUSION

Vaping prevalence was between 15.9% and 23.1% during pregnancy and the postpartum period, and the majority were dual users. Vaping habits of exclusive vapers remains stable throughout pregnancy and the postpartum. However, the vaping habits of dual users varies, with a third exclusively smoking in the postpartum.

Developing Graphic Messages for Vaping Prevention Among Black and Latino Adolescents: Participatory Research Approach

Background

As an important transition stage in human development, adolescence is a critical window for vaping prevention. There is a substantial gap in communication research on vaping prevention among racial and ethnic minority groups. Their representation is essential to develop, implement, and disseminate innovative and effective interventions for vaping prevention.

Objective

The aim of this study is to describe the participatory research (PR) procedures used with Black and Latino adolescents to develop culturally and linguistically appropriate graphic messages for vaping prevention.

Methods

This PR study used a qualitative, user-centered design method. We conducted a series of focus groups with 16 Black and Latino adolescents to develop culturally and linguistically appropriate graphic messages for vaping prevention. The biobehavioral model of nicotine addiction provided a framework for the development of the graphic messages. Participants met 4 times to provide iterative feedback on the graphic messages until they reached a consensus on overall quality and content.

Results

At baseline, the participants’ mean age was 15.4 years (SD 1.4). Of the participants, 50% (8/16) were female, 88% (14/16) were heterosexual, 56% (9/16) were Black/African American, and 44% (7/16) were Hispanic/Latino. A total of 12 of the 16 participants (75%) chose to participate in the English sessions. Participants decided to create four types of graphic messages: (1) financial reward, (2) health reward, (3) social norms, and (4) self-efficacy. Meeting 4 times with the 4 groups provided sufficient opportunities for iterative feedback on the graphic messages to reach a consensus on overall quality and content.

Conclusions

It is feasible and practical to build PR among Black and Latino adolescents focused on vaping prevention. Adolescents added innovation and creativity to the development of culturally and linguistically appropriate graphic messages for vaping prevention. Appropriate staffing, funding, and approaches are key for successful PR efforts among Black and Latino adolescents. Future research is needed to evaluate the impact of the graphic messages on vaping prevention.

Prevalence and characteristics of ever regular use of non-combustible nicotine for 1 year or more: a population survey in England

INTRODUCTION

Up-to-date monitoring of non-combustible nicotine products (e.g. e-cigarettes, nicotine replacement therapies (NRT), heated tobacco products (HTP); NNP) is important to assess their impact. To date, there is little evidence on the association between ever regular use (defined here as 1 year or more) of NNP and current smoking status.

AIMS/METHODS

The purpose of this study was to examine the prevalence, and sociodemographic, alcohol and smoking status correlates, of ever regular use of NNP in England in 2020. A cross-sectional survey of adults in England was conducted between February and June 2020.

RESULTS

A total of 8486 adults were surveyed; 94.9% (8055) were complete cases. The weighted prevalence of ever regular NNP use was 5.4% (n = 436; 95% CI 5.0-6.0), of which 82% (n = 360; 95% CI 78.7-85.8) was single and 18% (n = 79; 95% CI 14.8-22) multiple product use. Amongst ever regular NNP users, the prevalence of ever regular NRT, e-cigarette and HTP use was 64.7% (95% CI 60.1-69), 43.4% (95% CI 38.8-48) and 2.5% (95% CI 1.4-4.5), respectively. In adjusted analysis, ever regular NNP use was associated with smoking status, being significantly higher among current (22.3%; adjusted OR (aOR) 34.9, 95% CI 24.0-50.8) and ex-smokers (12.7%, aOR 19.8, 95% CI 11.1-14.4) than among never-smokers (0.6%). More advantaged occupational grade (aOR, 1.27 95% CI 1.02-1.57) and at least hazardous alcohol use (aOR, 1.38 95% CI 1.06-1.78) were associated with greater prevalence of ever regular NNP use.

CONCLUSIONS

Ever regularly using NNP was highest among smokers and ex-smokers and rare among never-smokers. Among people who have ever regularly used NNP, NRT is the most popular.

Improving on estimates of the potential relative harm to health from using modern ENDS (vaping) compared to tobacco smoking

BACKGROUND

Although the harm to health from electronic nicotine delivery systems (ENDS) compared to smoked tobacco remains highly uncertain, society and governments still need to know the likely range of the relative harm to inform regulatory policies for ENDS and smoking.

METHODS

We identified biomarkers with specificity of association with different disease groupings e.g., volatile organic compound (VOCs) for chronic obstructive pulmonary disease; and tobacco-specific N´-nitrosamines (TSNAs) and polycyclic aromatic hydrocarbons (PAHs) for all cancers. We conducted a review of recent studies (post January 2017) that compared these biomarkers between people exclusively using ENDS and those exclusively smoking tobacco. The percentage differences in these biomarkers, weighted by study size and adjusted for acrolein from other sources, were used as a proxy for the assumed percentage difference in disease harm between ENDS and smoking. These relative differences were applied to previously modelled estimates of smoking-related health loss (in health-adjusted life-years; HALYs).

RESULTS

The respective relative biomarker levels (ENDS vs smoking) were: 28% for respiratory diseases (five results, three studies); 42% for cancers (five results, four studies); and 35% for cardiovascular (seven results, four studies). When integrated with the HALY impacts by disease, the overall harm to health from ENDS was estimated to be 33% that of smoking.

CONCLUSIONS

This analysis, suggests that the use of modern ENDS devices (vaping) could be a third as harmful to health as smoking in a high-income country setting. But this estimate is based on a limited number of biomarker studies and is best be considered a likely upper level of ENDS risk given potential biases in our method (i.e., the biomarkers used being correlated with more unaccounted for toxicants in smoking compared to with using ENDS).

Systemic biomarkers of exposure associated with ENDS use: a scoping review

OBJECTIVE

This scoping review provides an overview of the existing literature on biomarkers of exposure from electronic nicotine delivery systems (ENDS) use and identifies gaps in existing knowledge.

DATA SOURCES

We searched two international databases (PubMed and Web of Science) to identify relevant studies published from August 2013 to February 2021.

DATA SELECTION

Studies were included if they assessed and compared biomarkers of exposure between exclusive ENDS users, non-users, exclusive cigarette smokers, dual users of ENDS and cigarettes or cigarette smokers who switch to ENDS.

DATA EXTRACTION AND SYNTHESIS

Of the 5074 studies identified, 188 studies met criteria and were selected for full-text screening. Of these, 27 studies were selected for inclusion and data extraction.

CONCLUSIONS

Consistent, although limited, evidence shows that exclusive ENDS users have elevated levels of biomarkers of certain volatile organic compounds (VOCs; eg, acrylamide and acrylonitrile), metals (eg, cadmium and selenium) and propylene glycol compared with non-users; however, evidence for biomarkers of other toxicants (eg, acrolein, benzene and chromium) is mixed. Biomarkers of most VOCs are lower in ENDS users compared with cigarette smokers, and cigarette smokers who switch to ENDS consistently show reductions in VOC biomarkers. Evidence comparing metal exposures from exclusive ENDS use, cigarette smoking and dual use is mixed and depends on the metal. ENDS and e-liquid characteristics as well as use patterns may be associated with elevated exposure to VOCs and metals. Additional rigorous, controlled studies can assess biomarker exposures from ENDS use and inform the overall risk-benefit of ENDS use for different user populations.

Impact of electronic cigarette ever use on lung function in adults aged 45-85: a cross-sectional analysis from the Canadian Longitudinal Study on Aging

OBJECTIVE

To describe the sociodemographic characteristics associated with e-cigarette ever use and to examine the impact of e-cigarette ever use on lung function impairment in an ageing population.

DESIGN

A cross-sectional analysis of data from the Canadian Longitudinal Study on Aging.

SETTING

A national stratified sample of 44 817 adults living in Canadian provinces.

PARTICIPANTS

Respondents included participants aged 45-85 and residing in the community in Canadian provinces.

OUTCOME MEASURES

The Global Lung Function Initiative normative values for forced expiratory volume in the first second (FEV₁), forced vital capacity (FVC), forced expiratory ratio (FEV₁/FVC) appropriate for age, sex, height and ethnicity were used to interpret the severity of lung function impairment. Multinomial logistic regression analysis was used to examine the impact of e-cigarette ever use on obstructive and restrictive lung function impairment.

RESULTS

The prevalence of e-cigarette ever use was 6.5% and varied by sociodemographic factors including higher prevalence among individuals younger than 65 years, those with lower education attainment and those with lower annual household income. E-cigarette ever use was associated with 2.10 (95% CI 1.57 to 2.08) times higher odds of obstructive lung function impairment after adjusting for conventional cigarette smoking and other covariates. Individuals with exposure to e-cigarette ever use and 15 or more pack-years had 7.43 (95% CI 5.30 to 10.38) times higher odds for obstructive lung function impairment when compared with non-smokers and non-e-cigarette users after adjusting for covariates. Smokers with 15 or more pack-years had higher odds of restrictive lung function impairment irrespective of e-cigarette ever use.

CONCLUSIONS

Ever use of e-cigarettes was found to be associated with obstructive lung function impairment after adjusting for covariates, suggesting that e-cigarette use may be adding to the respiratory and other chronic disease burden in the population.

[Diversification of smoking cessation programmes-the role of e-cigarettes]

The question of whether e‑cigarettes are a useful tool for smoking cessation is part of an ongoing and highly controversial scientific debate. In practice, however, the number of people trying to quit tobacco consumption by using these products is steadily increasing. This discussion article provides an outline of the current state of research on the issue of whether and to what extent e‑cigarettes can help people quit smoking.Of course, e‑cigarettes also have a certain potential for harm, especially if nicotine dependence is unnecessarily prolonged. Nevertheless, it can make an important contribution to harm reduction in nicotine consumption. Hence, the product should get treated as a serious alternative to nicotine replacement therapies (NRTs) in the scientific discussion. Like NRTs, e‑cigarettes offer a less harmful way of consuming nicotine that greatly reduces many of the health risks associated with tobacco consumption, such as the absorption of carcinogenic substances. Recent studies and reviews suggest that the product can be at least as effective as nicotine replacement therapies in helping people quit smoking. Individual studies even demonstrate the increased effectiveness of e‑cigarettes in supporting smoking cessation.Nevertheless, the review of the current literature shows that more high-quality research is needed to further understand the product and its properties. In terms of the harm reduction approach, however, it would already be more appropriate to also rely on e‑cigarettes instead of trying to force immediate and complete nicotine abstinence. After all, in the process of quitting smoking, the fastest possible cessation of the more unhealthy consumption of tobacco should be prioritized in order to immediately minimize unnecessary health risks.

Diacetyl and Other Ketones in e-Cigarette Aerosols: Some Important Sources and Contributing Factors

Background: Concerns over the presence of the diketones 2,4 butanedione (DA) and 2,3 pentanedione (AP) in e-cigarettes arise from their potential to cause respiratory diseases. Their presence in e-liquids is a primary source, but they may potentially be generated by glycerol (VG) and propylene glycol (PG) when heated to produce aerosols. Factors leading to the presence of AP, DA and acetoin (AC) in e-cigarette aerosols were investigated. We quantified direct transfer from e-liquids, examined thermal degradation of major e-liquid constituents VG, PG and 1,3 propanediol (1,3 PD) and the potential for AC, AP and DA production from sugars and flavor additives when heated in e-cigarettes.

Method: Transfers of AC, AP and DA from e-liquids to e-cigarette aerosols were quantified by comparing aerosol concentrations to e-liquid concentrations. Thermal generation from VG, PG or 1,3 PD e-liquids was investigated by measuring AC, AP and DA emissions as a function of temperature in an e-cigarette. Thermal generation of AC, AP and DA from sugars was examined by aerosolising e-liquids containing sucrose, fructose or glucose in an e-cigarette. Pyrolytic formation of AP and DA from a range of common flavors was assessed using flash pyrolysis techniques.

Results: AC transfer efficiency was >90%, while AP and DA were transferred less efficiently (65%) indicating losses during aerosolisation. Quantifiable levels of DA were generated from VG and PG, and to a lesser extent 1,3 PD at coil temperatures >300°C. Above 350°C AP was generated from VG and 1,3 PD but not PG. AC was not generated from major constituents, although low levels were generated by thermal reduction of DA. Aerosols from e-liquids containing sucrose contained quantifiable (>6 ng/puff) levels of DA at all sucrose concentrations tested, with DA emissions increasing with increasing device power and concentration. 1% glucose, fructose or sucrose e-liquids gave comparable DA emissions. Furanose ring compounds also generate DA and AP when heated to 250°C.

Conclusions: In addition to less than quantitative direct transfer from the e-liquid, DA and AP can be present in the e-cigarette aerosol due to thermal decomposition reactions of glycols, sugars and furanonse ring flavors under e-cigarette operating conditions.

1,2-Propylene Glycol: A Biomarker of Exposure Specific to e-Cigarette Consumption

Over the past decade, new emerging tobacco and nicotine-delivery products have changed the tobacco landscape. Especially, electronic cigarettes (ECs) have been suggested to be considered for tobacco harm reduction, reinforcing the need to identify novel biomarkers of exposure (BoE) specific to the EC use as this would complement exposure assessment and product compliance monitoring. Therefore, a sensitive LC-MS/MS method for the quantification of 1,2-propylene glycol (PG) and glycerol (G), the main e-liquid constituents, was established. PG and G were analyzed in plasma and urine samples from a clinical study comparing five nicotine product user groups, users of combustible cigarettes (CC), electronic cigarettes (EC), heated tobacco products (HTP), oral tobacco (OT), and oral/dermal nicotine delivery products (used for nicotine replacement therapy, NRT) with a control group of non-users (NU). Data demonstrate significantly elevated PG levels in urine and plasma in EC users compared to users of CC, HTP, NRT, OT as well as NU. In addition, PG in plasma and urine of vapers significantly correlated with nicotine (plasma) and total nicotine equivalents (urine), biomarkers reflecting product consumption, emphasizing the high specificity of PG as a BoE for EC consumption. We therefore suggest the use of PG as BoE in urine and/or plasma in order to monitor EC use compliance in exposure assessments.

Carcinogen Biomarkers in the Urine of Electronic Cigarette Users and Implications for the Development of Bladder Cancer: A Systematic Review

CONTEXT

Use of electronic cigarettes (e-cigarettes) has rapidly increased despite unclear longitudinal health effects. Once thought to be a safer alternative to tobacco smoke, it is possible that e-cigarettes expose the user to similar carcinogenic byproducts during the vaping process. These toxicants are metabolized and excreted in the urine, and may have oncogenic implications for bladder urothelium.

OBJECTIVE

To characterize and summarize known urinary carcinogenic biomarkers in e-cigarette users as they relate to the risk of developing bladder cancer.

EVIDENCE ACQUISITION

A systematic literature search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and included PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL). Relevant articles published in peer-reviewed journals, through January 2019, that reported on urinary biomarkers in e-cigarettes users were included. Parent compounds and urinary biomarkers were classified according to the International Agency for Research on Cancer Monographs on the Evaluation of Carcinogenic Risks to Humans and cross referenced using the Collaborative on Health and the Environment, Toxicant and Disease Database to determine a link to bladder cancer, grouped by strength of evidence.

EVIDENCE SYNTHESIS

Our initial search identified 1385 articles, 22 of which met final inclusion criteria and were included for analysis. In summation, these studies described 40 different parent compounds and four metals found in the urine of e-cigarette users. Since each parent compound can be metabolized several different ways, 63 unique toxicant or carcinogenic metabolite biomarkers were identified. Compared with nonuser controls, e-cigarette users had higher concentrations of urinary biomarkers of several carcinogenic compounds linked to bladder cancer. The majority of studies were limited by heterogeneous reporting and a dearth of control individuals who had never smoked.

CONCLUSIONS

Biomarkers of carcinogens, several with a strong link to bladder cancer, are present in the urine of e-cigarette users. Long-term implications of urothelial exposure to these toxicants are unknown but concerning, given the similarities to tobacco smoke and its established relationship with bladder cancer. Further study on the urological safety of e-cigarettes is necessary.

PATIENT SUMMARY

Our review shows that several carcinogens that have a known link to bladder cancer are present in the urine of electronic cigarette (e-cigarette) users. Further study on the urological safety of e-cigarettes is necessary.