Longitudinal transitions in e-cigarette and cigarette use among US adults: prospective cohort study

Background

To support tobacco control efforts, this study sought to characterize longitudinal transitions in use of electronic nicotine delivery systems (ENDS) and cigarettes.

Methods

Participants were nationally representative samples of 53,729 US adults from Waves 3-5 (2015-2019) of the Population Assessment of Tobacco and Health Study. We examined behavioral transitions (initiation, relapse, progression, and cessation) in ENDS and cigarette use across waves. Weighted generalized estimating equation models adjusted for sociodemographic variables.

Findings

Of never ENDS users at baseline, an estimated 1.7% reported initiating ENDS use by follow-up. Of former ENDS users, an estimated 12.1% relapsed into ENDS use. Of periodic ENDS users at baseline, 13% progressed to established ENDS use. Of baseline current ENDS users, 46.3% discontinued ENDS use. The corresponding transitions for cigarette smoking were 1.6% (initiation), 4.8% (relapse), 21.1% (progression), and 14% (discontinuation). Adults aged 18-24 (vs. older age), Hispanics (vs. non-Hispanic white), and past 12-month cannabis users were more likely to initiate ENDS or cigarettes (all p < 0.05). Having any internalizing mental health symptoms increased the odds of ENDS initiation, while externalizing symptoms increased the odds of cigarette initiation. Those who perceived nicotine as very harmful (vs. none/low harm) were more likely to discontinue ENDS. Current cigarette users (vs. non-users) at baseline were more likely to initiate, relapse, or discontinue ENDS (all p < 0.05) and vice versa.

Interpretation

We observed high changeability in ENDS and cigarette use among US adults over time. In absolute terms, ENDS use grew, while smoking fell. Tobacco control programs should focus on priority populations, including young adults and people with internalizing and externalizing mental health symptoms.

Funding

National Institutes of Health, R01-CA246606-01A1, R01-DA048390.

e-Cigarettes Used by Adolescents to Try to Quit Smoking Are Associated With Less Quitting: A Cross-Sectional Analysis of the National Youth Tobacco Survey

PURPOSE

This paper determines the association between youth e-cigarette use "to try to quit using other tobacco products, such as cigarettes" and having stopped smoking cigarettes (defined as an ever cigarette smoker who did not smoke in the past 30 days).

METHODS

This study uses data from the NYTS from 2015 through 2021, focusing on youth who started smoking cigarettes before they started using e-cigarettes. Associations between using e-cigarettes to quit and having stopped smoking were computed using logistic regression accounting for the complex survey design and adjusting for level of nicotine dependence, year, age, gender, and race/ethnicity. Sensitivity analyses allowed for having started cigarettes and e-cigarettes in the same year and without regard for starting sequence.

RESULTS

The primary analytic subsample included 6435 United States middle and high school students (mean age 15.9 years, 55.4% male). Using e-cigarettes to quit was associated with significantly lower odds of having stopped smoking cigarettes (odds ratio, 0.62; 95% confidence interval, 0.45-0.85), controlling for nicotine dependence and demographics. Youth with higher levels of nicotine dependence also had lower odds of having stopped smoking. The results were stable over time. Sensitivity analyses produced similar results.

DISCUSSION

Ever-smoking youth who used e-cigarettes "to try to quit using other tobacco products, such as cigarettes" had lower odds of having stopped smoking cigarettes than those who did not use e-cigarettes as to try to quit. Physicians, regulators, and educators should discourage youth from attempting to use e-cigarettes as a way to stop smoking cigarettes.

Intended and unintended effects of e-cigarette taxes on youth tobacco use

Over the past decade, rising youth use of e-cigarettes and other electronic nicotine delivery systems (ENDS) has contributed to aggressive regulation by state and local governments. Between 2010 and mid-2019, ten states and two large counties adopted ENDS taxes. We use two large national surveys (Monitoring the Future and the Youth Risk Behavior Surveillance System) to estimate the impact of ENDS taxes on youth tobacco use. We find that ENDS taxes reduce youth ENDS consumption, with estimated ENDS tax elasticities of -0.06 to -0.21. However, we estimate sizable positive cigarette cross-tax effects, suggesting economic substitution between cigarettes and ENDS for youth. These substitution effects are particularly large for frequent cigarette smoking. We conclude that the unintended effects of ENDS taxation may considerably undercut or even outweigh any public health gains.

The role of synthetic coolants, WS-3 and WS-23, in modulating E-cigarette-induced reactive oxygen species (ROS) in lung epithelial cells

There has been a substantial rise in e-cigarette (e-cig) use or vaping in the past decade, prompting growing concerns about their adverse health effects. Recently, e-cig manufacturers have been using synthetic cooling agents, like WS-23 and WS-3, to provide a cooling sensation without the "menthol taste". Studies have shown that aerosols/vapes generated by e-cigs can contain significant levels of reactive oxygen species (ROS). However, studies investigating the role of synthetic coolants in modulating ROS levels generated by e-cigs are lacking. This study seeks to understand how synthetic coolants, e-cig additives that have become increasingly prevalent in e-liquids sold in the United States (US), impact acellular ROS production from e-liquid aerosols as well as cellular ROS levels from pulmonary epithelial cells exposed to these e-liquids. To further explain, our study aims to understand whether the addition of WS-3 and WS-23 to e-liquid base and e-liquid base with nicotine significantly modifies generated acellular ROS levels within aerosolized e-liquids, as well as cellular ROS within BEAS-2B cells treated with these same e-liquids. Aerosols were generated from e-liquids with and without synthetic coolants through a single-puff aerosol generator; subsequently, acellular ROS was semi-quantified in H2O2 equivalents via fluorescence spectroscopy. Our acellular ROS data suggest that adding WS-3 to e-liquid base (PG:VG), regardless of nicotine content, has a minimal impact on modifying e-cig generated acellular ROS levels. Additionally, we also measured cellular ROS in lung epithelial cells using both e-liquids containing and not containing synthetic coolants via the CellROX Green fluorescent sensor. Similar comparable results were found in BEAS2B cells though ROS was increased by WS-3 and WS-23 treated in e-cig nicotine groups. Altogether, our data suggest that neither the addition of WS-23 nor WS-3 to e-liquid base solution, with and without nicotine, significantly modifies e-cig generated acellular ROS levels within aerosolized e-liquids and cellular ROS levels within treated BEAS-2B cells. Together, our data provide insight into whether synthetic coolants added to e-liquids could impact vaping-induced oxidative stress in the lungs.

The development and validation of an electronic nicotine delivery system (ENDS) image cue stimulus set

RATIONALE

Responsiveness to drug-related cues assesses drug reward in research studies. There are currently no validated visual image cues related to electronic nicotine delivery systems (ENDS), thus, this study aimed to develop and validate affective ENDS image cues.

METHODS

ENDS users and non-vaping individuals in the United States and Canada were recruited via Amazon MTurk. A total of 120 ENDS-related images and 56 neutral images, matched for visual similarity, were assessed. These images were either selected from public databases or were photographed by study staff. Closely adhering to the International Affective Picture System procedure, each participant rated 66 images one-by-one on dimensions of valence, arousal, dominance, and desire-to-vape where higher scores indicated greater feelings of happiness, excitement, loss of control, and desire to vape.

RESULTS

After excluding patterned responses, the data from 926 participants (610 ENDS users, and 316 non-vaping controls) were analyzed. When viewing ENDS-related images, desire-to-vape scores were correlated with valence (r = 0.55, p < 0.0005), arousal (r = 0.72, p < 0.0005), and dominance (r = 0.58, p < 0.0005) scores. Images that elicited greater desires to vape also elicited greater feelings of happiness and excitement, but less perceived control. Correlations between arousal and valence (r = 0.42, p < 0.0005) and dominance (r = 0.71, p < 0.0005) suggest that images that increased feelings of excitement also increased happiness and decreased perceived control.

CONCLUSIONS

Correlational findings of the affective ENDS-related images were similar to those of previous studies validating collections of tobacco and alcohol picture cues, supporting the future use of these stimuli in ENDS research.

Analysis of common methodological flaws in the highest cited e-cigarette epidemiology research

The prevalence of vaping, also known as using e-cigarettes, vapes and vape pens, has prompted a demand for reliable, evidence-based research. However, published literature on the topic of vaping often raises concerns, characterized by serious flaws and a failure to adhere to accepted scientific methodologies. In this narrative review, we analyze popular vaping studies published in medical journals that purport to evaluate the association of vaping and smoking cessation, smoking initiation or health outcomes. We analyzed 24 included studies to identify the questions they claimed to address, stated methods, manner of implementation, discussions, and stated conclusions. After critical appraisal, we noted a multiplicity of flaws in these studies, and identified patterns as to the nature of such flaws. Many studies lacked a clear hypothesis statement: to the extent that a hypothesis could be inferred, the methods were not tailored to address the question of interest. Moreover, main outcome measures were poorly identified, and data analysis was further complicated by failure to control for confounding factors. The body of literature on "gateway" theory for the initiation of smoking was particularly unreliable. Overall, the results and discussion contained numerous unreliable assertions due to poor methods, including data collection that lacked relevance, and assertions that were unfounded. Many researchers claimed to find a causal association while not supporting such findings with meaningful data: the discussions and conclusions of such studies were, therefore, misleading. Herein, we identify the common flaws in the study design, methodology, and implementation found in published vaping studies. We present our summary recommendations for future vaping research. Our aim is to prompt future researchers to adhere to scientific methods to produce more reliable findings and conclusions in the field of vaping research.

Electronic nicotine delivery systems (ENDS) cue reactivity in dual users: A combined analysis

BACKGROUND

Cigarette smokers report increases in smoking urge in response to exposure to electronic nicotine delivery systems (ENDS) and dual users, i.e. smokers who also vape ENDS, may exhibit greater cue reactivity than exclusive smokers. The current investigation examined reactivity to a variety of ENDS cues across a large sample of cigarette smokers and dual ENDS users.

METHODS

Young adult smokers (N = 345; >5 cigarettes per day) were recruited between 2013-2019 for participation in a series of within-subjects laboratory-based studies. Participants completed surveys before and after exposure to a confederate-delivered control cue (water) and an active cue, including cigarette or ENDS cues ranging from first generation "cigalikes" to a fourth generation "pod-mod". Main outcomes were post-cue changes in desire for combustible cigarettes and e-cigarettes, and smoking behavior as determined by the smoking latency portion of the Smoking Lapse Paradigm after cue exposure.

RESULTS

Relative to smokers who do not use ENDS, dual users demonstrated higher baseline desire for ENDS and greater ENDS cue reactivity (across product types) in terms of post-cue increases in smoking urge and shorter latency to smoking choice. In contrast, reactivity to the cigarette cue was similar across groups.

CONCLUSIONS

Dual users show heightened ENDS cue reactivity on smoking urge and behavior relative to never users of ENDS, regardless of the type of ENDS cue. Given their reactivity to both cigarette and ENDS cues, it may be difficult for dual users to transition to exclusive vaping or quit tobacco product use altogether.

Dripping Technology Use Among Young Adult E-Cigarette Users

BACKGROUND

Young adults are increasingly using electronic nicotine delivery systems (ENDS). The standard ENDS device involves an electric coil that heats a wick to vaporize an e-liquid solution. "Dripping" is another method that involves applying e-liquid directly to the coil. Dripping increases risk of harmful toxic compounds in vapor aerosols. Despite evidence of high levels of dripping among adolescents, young adult prevalence is unknown.

METHODS

Young adults aged 18 to 24 completed an online survey assessing vaping and dripping status, type of devices used, tobacco use, and vaping expectancies. Among ever-vapers, univariate and multivariate logistic regression models assessed whether demographics predicted dripping and use of dripping devices. Multivariate Analysis of Variance compared never- and ever-drippers on expectancies for vaping outcomes.

RESULTS

Over 2 in 5 young adult ever-vapers (43.7%) reported dripping. A multivariate regression model found that male gender (AOR = 1.83), identifying as White (AOR = 2.37), and use of other tobacco products (hookah; AOR = 1.91; cigars; AOR = 2.26; cigarettes; AOR = 2.51) were associated with dripping. E-cigarette users who reported lifetime dripping were more likely to consider vaping stimulating, socially facilitating, and flavorful. They ascribed lower health risks to vaping and felt it could reduce negative affect, weight gain, nicotine cravings, and boredom (all P < .05).

CONCLUSION

Dripping was a highly prevalent behavior among this sample of young adults, particularly among White males. These findings point to the importance of gaining a greater understanding of the drivers and consequences of vaping and dripping behavior.

Cannabis, Vaping, and Respiratory Symptoms in a Probability Sample of U.S. Youth

PURPOSE

The purpose of this study was to explore the association between respiratory symptoms among U.S. adolescents who were current (past 30-day) users of cigarettes, e-cigarettes, and/or cannabis, as well as lifetime users of cannabis with electronic nicotine delivery systems (ENDS).

METHODS

Wave 4 from a national probability sample (N = 14,798) of adolescents (12-17 years) using Population Assessment of Tobacco and Health Study data was used for this study. Retention rate was 88.4%.

RESULTS

The odds of indicating "wheezing or whistling" in the chest were roughly two times higher among those who had used cannabis in ENDS (adjusted odds ratio 1.81, 95% confidence interval 1.47-2.22); neither e-cigarettes nor cigarettes had a significant association with all five respiratory symptoms in the fully adjusted models.

CONCLUSIONS

This study provides preliminary evidence that adolescents' cannabis use with ENDS may have negative health consequences. Lifetime cannabis use with ENDS was substantially associated with higher odds of respiratory symptoms.

Sub-ohm vaping increases the levels of carbonyls, is cytotoxic, and alters gene expression in human bronchial epithelial cells exposed at the air-liquid interface

Background

Exposure to electronic-cigarette (e-cig) aerosols induces potentially fatal e-cig or vaping-associated lung injury (EVALI). The cellular and molecular mechanisms underlying these effects, however, are unknown. We used an air–liquid interface (ALI) in vitro model to determine the influence of two design characteristics of third-generation tank-style e-cig devices—resistance and voltage—on (1) e-cig aerosol composition and (2) cellular toxicity.

Methods

Human bronchial epithelial cells (H292) were exposed to either butter-flavored or cinnamon-flavored e-cig aerosols at the ALI in a Vitrocell exposure system connected to a third-generation e-cig device. Exposures were conducted following a standard vaping topography profile for 2 h per day, for 1 or 3 consecutive days. 24 h after ALI exposures cellular and molecular outcomes were assessed.

Results

We found that butter-flavored e-cig aerosol produced under ‘sub-ohm’ conditions (< 0.5 Ω) contains high levels of carbonyls (7–15 μg/puff), including formaldehyde, acetaldehyde and acrolein. E-cig aerosol produced under regular vaping conditions (resistance > 1 Ω and voltage > 4.5 V), contains lower carbonyl levels (< 2 μg/puff). We also found that the levels of carbonyls produced in the cinnamon-flavored e-cig aerosols were much lower than that of the butter-flavored aerosols. H292 cells exposed to butter-flavored or cinnamon-flavored e-cig aerosol at the ALI under ‘sub-ohm’ conditions for 1 or 3 days displayed significant cytotoxicity, decreased tight junction integrity, increased reactive oxygen species production, and dysregulated gene expression related to biotransformation, inflammation and oxidative stress (OS). Additionally, the cinnamon-flavored e-cig aerosol induced pro-oxidant effects as evidenced by increases in 8-hydroxy-2-deoxyguanosine protein levels. Moreover, we confirmed the involvement of OS as a toxicity process for cinnamon-flavored e-cig aerosol by pre-treating the cells with N-acetyl cysteine (NAC), an antioxidant that prevented the cells from the OS-mediated damage induced by the e-cig aerosol.

Conclusion

The production of high levels of carbonyls may be flavor specific. Overall, inhaling e-cig aerosols produced under ‘sub-ohm’ conditions is detrimental to lung epithelial cells, potentially via mechanisms associated with OS. This information could help policymakers take the necessary steps to prevent the manufacturing of sub-ohm atomizers for e-cig devices.

Sub-ohm vaping increases the levels of carbonyls, is cytotoxic, and alters gene expression in human bronchial epithelial cells exposed at the air-liquid interface

BACKGROUND

Exposure to electronic-cigarette (e-cig) aerosols induces potentially fatal e-cig or vaping-associated lung injury (EVALI). The cellular and molecular mechanisms underlying these effects, however, are unknown. We used an air-liquid interface (ALI) in vitro model to determine the influence of two design characteristics of third-generation tank-style e-cig devices-resistance and voltage-on (1) e-cig aerosol composition and (2) cellular toxicity.

METHODS

Human bronchial epithelial cells (H292) were exposed to either butter-flavored or cinnamon-flavored e-cig aerosols at the ALI in a Vitrocell exposure system connected to a third-generation e-cig device. Exposures were conducted following a standard vaping topography profile for 2 h per day, for 1 or 3 consecutive days. 24 h after ALI exposures cellular and molecular outcomes were assessed.

RESULTS

We found that butter-flavored e-cig aerosol produced under 'sub-ohm' conditions (< 0.5 Ω) contains high levels of carbonyls (7-15 μg/puff), including formaldehyde, acetaldehyde and acrolein. E-cig aerosol produced under regular vaping conditions (resistance > 1 Ω and voltage > 4.5 V), contains lower carbonyl levels (< 2 μg/puff). We also found that the levels of carbonyls produced in the cinnamon-flavored e-cig aerosols were much lower than that of the butter-flavored aerosols. H292 cells exposed to butter-flavored or cinnamon-flavored e-cig aerosol at the ALI under 'sub-ohm' conditions for 1 or 3 days displayed significant cytotoxicity, decreased tight junction integrity, increased reactive oxygen species production, and dysregulated gene expression related to biotransformation, inflammation and oxidative stress (OS). Additionally, the cinnamon-flavored e-cig aerosol induced pro-oxidant effects as evidenced by increases in 8-hydroxy-2-deoxyguanosine protein levels. Moreover, we confirmed the involvement of OS as a toxicity process for cinnamon-flavored e-cig aerosol by pre-treating the cells with N-acetyl cysteine (NAC), an antioxidant that prevented the cells from the OS-mediated damage induced by the e-cig aerosol.

CONCLUSION

The production of high levels of carbonyls may be flavor specific. Overall, inhaling e-cig aerosols produced under 'sub-ohm' conditions is detrimental to lung epithelial cells, potentially via mechanisms associated with OS. This information could help policymakers take the necessary steps to prevent the manufacturing of sub-ohm atomizers for e-cig devices.

Electronic nicotine delivery systems (ENDS): not still ready to put on END

In recent years, the marketing of electronic nicotine delivery systems (ENDS) has changed the attitudes of people towards tobacco products. In addition, ENDS are becoming very popular among youth. Since a high percentage of young people use these delivery systems as the first products containing nicotine, the acute and chronic exposure to ENDS emissions and nicotine-induced effects on the adolescent's brain deserve a special attention. Given the extremely varied types of ENDS and the heterogeneous concentrations of substances emitted by specific devices, an overall risk assessment is particularly difficult. Here we critically review the evidence on the safety profile of ENDS, we also discuss the global policies with the leading role of the World Health Organization (WHO), which provides updated information and indications that must guide community and individual choices.

Effect of aerosolized nicotine on human bronchial epithelial cells is amplified after co-administration with cannabidiol (CBD): a pilot in vitro study

Background

Population-based studies suggest increasing rates of concurrent use of vaping products that contain either nicotine or cannabinoids. The aim of this pilot study was to test in vitro the acute inhalation toxicity of vaporized flavored and unflavored nicotine solutions co-administered with cannabidiol (CBD).

Methods

Bronchial epithelial cells (H292) were exposed directly to aerosol generated from electronic cigarettes refilled with propylene glycol only, unflavored nicotine solutions in propylene glycol with and without CBD, as well as to solutions containing only CBD. Cells were also exposed to a commercially available flavored solution containing nicotine and CBD. The in vitro toxicological effects were assessed after exposure using the following methods: 1) a trypan blue exclusion assay (cell viability), 2) neutral red uptake assay (metabolic activity) and 3) ELISA (concentrations of inflammatory mediators).

Results

Unflavored solution containing only CBD was significantly more cytotoxic than unflavored solution containing only nicotine. Unflavored solution containing both CBD and nicotine was significantly more cytotoxic than unflavored solutions with only nicotine. Levels of released cytokines were significantly higher when cells were co-exposed to nicotine and CBD as compared to cells exposed to only nicotine or only CBD. Overall, flavored products showed increased toxicity as compared to unflavored solutions.

Conclusions

This pilot in vitro study suggests independent and additive toxic effects of vaporized nicotine and CBD. Observed toxic effects are accentuated by flavorings. Future studies are needed to determine the potential long-term health consequences of concurrent use of vaporized nicotine and cannabis products.

School proximity and census tract correlates of e-cigarette specialty retail outlets (vape shops) in central Texas

E-cigarettes are the most widely used tobacco product among middle and high school students in the United States. This study investigates the proximity of e-cigarette retail outlets (vape shops) to middle and high schools in Austin, Texas, as well as the sociodemographic determinants of outlet presence, at the census tract level. A proximity analysis was conducted using school geo-data derived from the Texas Education Agency and vape shop geo-data derived from a validated online search. Logistic regressions using 5-year estimates of the 2014 American Community Survey were performed to determine the correlates of vape shop presence in census tracts. Overall, 20% of the census tracts in Austin, Texas, had at least one vape shop. The proportion of vape shop-containing census tracts that met the criteria for classification as a “poverty area” (36.5%) was greater than that of vape shop-free census tracts (26.3%). Vape shops were more likely to be present in census tracts classified as poverty areas; however, the odds of vape shop presence declined as the percentage of the non-Hispanic Black population and the percentage of persons aged 10–14 years in census tracts increased. About 40% of the vape shops were located within 0.5 miles of a middle or high school. Sociodemographic disparities exist in the e-cigarette retail environment. In addition to the need to address the disparities identified in this study, our results showing the presence of vape shops within walkable distances of schools calls for tighter regulations and continued surveillance around the marketing practices of e-cigarette retailers.

Adverse Experience Reports of Seizures in Youth and Young Adult Electronic Nicotine Delivery Systems Users

PURPOSE

Electronic nicotine delivery systems (ENDS) use poses significant and avoidable health risks to young people. Until recently, seizures were most often associated with cases of liquid nicotine ingestion.

METHODS

We examined 122 voluntary reports of seizures (n = 114) and neurological symptoms (syncope, n = 7; and tremor, n = 1) in 123 ENDS users (one report contained information on two users) received by the Food and Drug Administration between December 1, 2010, and June 30, 2019.

RESULTS

The median age (interquartile range) of users was 20 years (17-27); 67% of reports were in youth and young adults aged 14-24 years. Fifty-one (41%) reported other underlying medical conditions, including previous history of anxiety (n = 11), attention deficit hyperactivity disorder (n = 7), seizure (n = 6), and depression (n = 5). Of the 79 reports with available information, 67 (85%) reported seizure occurred within 24 hours of last use; 49 (62%) reported seizure within 30 minutes. The potential impact of concomitant use of marijuana or cannabidiol oil could not be evaluated from the eight reports that mentioned concomitant use.

CONCLUSIONS

Findings suggest an association between ENDS use and seizures. Additional information will help to clarify the relationship between ENDS use and seizures and to understand how product attributes such as nicotine content, formulation, quantity, and other ingredients or contaminants may contribute to seizures. It is important that health care providers ask about ENDS use when evaluating neurological symptoms and that users, parents, school personnel, and health care providers report adverse experiences involving tobacco products to Food and Drug Administration via the Safety Reporting Portal (www.safetyreporting.hhs.gov).

Motivations for using electronic cigarettes in young adults: A systematic review

Background: The most common reasons why adults use e-cigarettes are to stop or reduce tobacco smoking. However, it is unclear if this reason is evenly distributed between young and older adults. Objectives: describe the motivations for e-cigarette use amongst young adults aged 18-25 and compare the reasons for using e-cigarettes of people who currently or formerly used tobacco products to those who had never smoked tobacco prior e-cigarette use. Methods: PubMed^®, Scopus^®, Cochrane Library^®, SocINDEX^®, PsycARTICLES^®, Psychology and Behavioral Sciences Collection^® and PsycINFO^® databases were used. English written articles were screened up to March 2018. Depending on study design, quality was assessed using The STROBE or RATS checklists. Results: Six articles were included in the review, all with a moderate quality of evidence. Independently of smoking status, curiosity was the most frequently reported reason for initiating the use of e-cigarettes in young adults. Reasons for continuing to use e-cigarettes were various. The continued use of e-cigarettes could be either a means to replicate smoking habits, or a way for a different and personalized use of nicotine by inhalation. Conclusions: Reasons for using e-cigarettes in young adults are varied and are not limited to stopping smoking.

Nonanimal toxicology testing approaches for traditional and deemed tobacco products in a complex regulatory environment: Limitations, possibilities, and future directions

The evaluation of tobacco products is complex due to a multitude of factors including product diversity, limited testing standards, and variability in user behavior. Alternative approaches in current testing paradigms have limitations that generally truncate their applicability beyond screening for hazard identification; this is also true for toxicological evaluations of tobacco products. In a regulatory context, results from tobacco product toxicity assessments are extrapolated to the in vivo condition to assess human health relevance at the individual and population level. A key limitation of alternative approaches is the difficulty and uncertainty in extrapolating results to adverse outcomes relevant to chronic tobacco exposures in humans. This difficulty and uncertainty are increased when comparing toxicological outcomes between tobacco products. Given that the interpretation and quantification of differences in assay results (e.g., mutagenicity) for tobacco product comparison may be inconclusive, the predictive value of these approaches for human risk of relevant downstream pathologies (e.g., carcinogenesis) can be limited. Development and validation of fit-for-purpose alternative approaches that are predictive of human toxicity and dose response assays with adequate sensitivity and specificity for product comparisons would help advance the field of predictive toxicology.

Comparative effects of parent and heated cinnamaldehyde on the function of human iPSC-derived cardiac myocytes

Many e-cigarette products contain cinnamaldehyde as a primary constituent of cinnamon flavorings. When used as a food additive, cinnamaldehyde is generally regarded as safe for ingestion. However, little is known about the effects of cinnamaldehyde or its degradation products, generated after heating and inhalation, which may lead to elevated circulatory exposure to the heart. Hence, in this study, we tested the in vitro cardiac toxicity of cinnamaldehyde and its thermal degradation products generated by heating at low (200 ± 50 °C) and high temperatures (700 ± 50 °C) on the contractility, rhythmicity and electrical signaling properties of human induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs). Cellular impedance measurements on spontaneously beating hiPSC-CMs revealed that cinnamaldehyde significantly alters contraction-dependent signal amplitude, beating rate, and cell morphology. These effects were attenuated after cinnamaldehyde was subjected to heating at low or high temperatures. Current clamp analysis of hiPSC-CM action potentials (APs) showed only modest effects of acute application of 1-100 μM cinnamaldehyde on resting membrane potential, while prolonged (~20 min) application of 100 μM cinnamaldehyde resulted in progressive depolarization and loss of rhythmic AP spiking activity. Collectively, these results suggest that micromolar levels of cinnamaldehyde could alter cardiac excitability, in part by impairing the processes that regulate membrane potential and depolarization. Our results further suggest that heating cinnamaldehyde by itself does not directly lead to the formation of products with greater cardiotoxicity in vitro.

Perceived health risks of electronic nicotine delivery systems (ENDS) users: The role of cigarette smoking status

INTRODUCTION

Use of electronic nicotine delivery systems (ENDS) has increased markedly. We examined how current ENDS users differ in perceptions of tobacco and ENDS-related health risks as a function of cigarette smoking status.

METHODS

We classified 1329 current ENDS users completing a national online survey based on cigarette smoking status, and employed linear and logistic regression to assess group differences in perceptions of tobacco-related health risks.

RESULTS

The sample consisted of 38% Current Cigarette Smokers, 40% Former Cigarette Smokers, and 22% Non-Smokers. Our targeted recruitment strategy yielded a balance of key descriptive variables across participants. Significant differences were observed in race, employment and marital status across cigarette smoking status, but not in gender, education, income, or sexual orientation. Participants reported considerable perceived knowledge about health risks associated with tobacco use, but less regarding ENDS use. Current Smokers rated ENDS use as riskier than Non-Smokers, and considered cigarette use less risky for both users and bystanders. Current Smokers were more likely to perceive cardiovascular diseases, diabetes and cancer as the health risks associated with ENDS use. Former Smokers were more likely to perceive such risks with traditional tobacco use. Further, regardless of smoking status, perceived knowledge about the health risks of tobacco or ENDS use was positively associated with perceived likelihood of high risks of cardiovascular diseases and cancer.

CONCLUSIONS

Among current ENDS users, there were significant differences in perceived health risks based on cigarette smoking history. Improved health messaging can be achieved when cigarette smoking status is taken into account.

Weighing the Risks and Benefits of Electronic Cigarette Use in High-Risk Populations

This article reviews the current evidence on electronic cigarette (e-cigarette) safety and efficacy for smoking cessation, with a focus on smokers with cardiovascular disease, pulmonary disease, or serious mental illness. In the United States, adult smokers use e-cigarettes primarily to quit or reduce cigarette smoking. An understanding of the potential risks and benefits of e-cigarette use may help clinicians counsel smokers about the potential impact of e-cigarettes on health.

A distributed computational model for estimating room air level of constituents due to aerosol emission from e-vapor product use

Most indoor air quality models reported in the literature are well-mixed models. A well-mixed model estimates the room average concentration of constituents from sources. It does not provide information on (1) how far and how fast the emitted chemicals travel in the indoor space? And (2) how the concentration changes as a function of distance from the emission source? We developed a distributed model, using computational fluid dynamics and thermodynamics principles, which allows for aerosol dispersion in an indoor space and includes evaporation and condensation of constituents in a multi-compound aerosol mixture. The distributed model can estimate the spatial and temporal variations of the concentration of individual constituents present in the emitted aerosol in vapor and particulate phases separately. Results from the model were compared with the published experimental data and were found to be in good agreement. A sensitivity analysis was performed to evaluate the impact of various parameters that affect the air level of the emitted constituents within an indoor space, including rate of emission, the rate of air exchange, etc. The model can also be used to estimate the level of second hand exposure in a confined space where e-vapor products (EVPs) are used.

Arguments for amending smoke-free legislation in U.S. states to restrict use of electronic nicotine delivery systems

The uneven diffusion of local and state laws restricting the use of electronic nicotine delivery systems (ENDS) in the United States may be a function of inconclusive scientific evidence and lack of guidance from the federal government. The objective of this study was to assess whether the rationale for amending clean indoor air acts (CIAAs) is being conflated by issues that are not directly relevant to protecting the health of ENDS non-users. Online sources were used in identifying bills (n = 25) that were presented in U.S. state legislatures from January 2009 to December 2015. The bills were categorized into one of three groups: 1) bills amending comprehensive CIAAs (n = 11), 2) bills prohibiting use of ENDS in places frequented by youth (n = 5), and 3) remaining bills that varied between the two categories (n = 9). Arguments presented in committee hearings were coded as scientific, public health, economic, enforcement, freedom, or regulatory. Arguments pertaining to amendment of clean indoor air acts spanned several categories, many of which were not directly relevant to the aims of the legislation. This finding could assist lawmakers and expert witnesses in making arguments that yield greater success in amending legislation. Alternatively, inconclusive scientific data on the hazards of ENDS aerosols might encourage lawmakers to propose legislation that prohibits ENDS use in places frequented by youths.

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Arguments pertaining to amendment of smoke-free laws spanned several categories.

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Harm reduction was used often in opposing amendments to smoke-free laws.

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Arguments pertaining to harm of ENDS aerosols were obfuscated by conflicting data.

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Lawmakers should consider legislation prohibiting ENDS use in youth-oriented places.