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AimsWe reviewed available research on the use, content and safety of electronic cigarettes (EC), and on their effects on users, to assess their potential for harm or benefit and to extract evidence that can guide future policy.MethodsStudies were identified by systematic database searches and screening references to February 2014.ResultsEC aerosol can contain some of the toxicants present in tobacco smoke, but at levels which are much lower. Long-term health effects of EC use are unknown but compared with cigarettes, EC are likely to be much less, if at all, harmful to users or bystanders. EC are increasingly popular among smokers, but to date there is no evidence of regular use by never-smokers or by non-smoking children. EC enable some users to reduce or quit smoking.ConclusionsAllowing EC to compete with cigarettes in the market-place might decrease smoking-related morbidity and mortality. Regulating EC as strictly as cigarettes, or even more strictly as some regulators propose, is not warranted on current evidence. Health professionals may consider advising smokers unable or unwilling to quit through other routes to switch to EC as a safer alternative to smoking and a possible pathway to complete cessation of nicotine use.

Introduction: Electronic cigarette (EC) use has increased rapidly in the last decade, especially among youth. Regulating nicotine delivery from ECs could help curb youth uptake and leverage EC use in harm reduction yet is complicated by varying device and liquid variables that affect nicotine delivery. Nicotine flux, the nicotine emission rate, is a parameter that incorporates these variables and focuses on the performance rather than the design of an EC. Nicotine flux therefore could be a powerful regulatory tool if it is shown empirically to predict nicotine delivery and subjective effects related to dependence. Methods and analysis: This project consists of two complementary clinical trials. In Trial I, we will examine the relationship between nicotine flux and the rate and dose of nicotine delivery from ECs, hence, impacting abuse liability. It will also examine the extent to which this relationship is mediated by nicotine form (i.e., freebase versus protonated). At Yale School of Medicine (YSM), study participants will puff EC devices under conditions that differ by flux and form, while arterial blood is sampled in high time resolution. In Trial II, we will assess the relationship between nicotine flux, form, and subjective effects. At the American University of Beirut (AUB), participants will use EC devices with varying nicotine fluxes and forms, while dependency measures, such as the urge to use ECs, nicotine craving, and withdrawal symptoms, will be assessed. We will also monitor puffing intensity and real-time exposure to toxicants. Ethics and dissemination: The protocol of Trial I and Trial II was approved by YSM and AUB IRBs, respectively. We will disseminate study results through peer-reviewed publications and conference presentations. Trial registration: NCT05706701 for Trial I and NCT05430334 for Trial II. [ABSTRACT FROM AUTHOR]

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

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

Background: In total, 3.2% of American adults report using e-cigarettes every day or some days. The Vaping and Patterns of E-cigarette Use Research (VAPER) Study is a web-based longitudinal survey designed to observe patterns in device and liquid use that suggest the benefits and unintended consequences of potential e-cigarette regulations. The heterogeneity of the e-cigarette devices and liquids on the market, the customizability of the devices and liquids, and the lack of standardized reporting requirements result in unique measurement challenges. Furthermore, bots and survey takers who submit falsified responses are threats to data integrity that require mitigation strategies. Objective: This paper aims to describe the protocols for 3 waves of the VAPER Study and discuss recruitment and data processing experiences and lessons learned, including the benefits and limitations of bot- and fraudulent survey taker-related strategies. Methods: American adults (aged ≥21 years) who use e-cigarettes ≥5 days per week are recruited from up to 404 Craigslist catchment areas covering all 50 states. The questionnaire measures and skip logic are designed to accommodate marketplace heterogeneity and user customization (eg, different skip logic pathways for different device types and customizations). To reduce reliance on self-report data, we also require participants to submit a photo of their device. All data are collected using REDCap (Research Electronic Data Capture; Vanderbilt University). Incentives are US $10 Amazon gift codes delivered by mail to new participants and electronically to returning participants. Those lost to follow-up are replaced. Several strategies are applied to maximize the odds that participants who receive incentives are not bots and are likely to possess an e-cigarette (eg, required identity check and photo of a device). Results: In total, 3 waves of data were collected between 2020 and 2021 (wave 1: n=1209; wave 2: n=1218; wave 3: n=1254). Retention from waves 1 to 2 was 51.94% (628/1209), and 37.55% (454/1209) of the wave 1 sample completed all 3 waves. These data were mostly generalizable to daily e-cigarette users in the United States, and poststratification weights were generated for future analyses. Our data offer a detailed examination of users' device features and specifications, liquid characteristics, and key behaviors, which can provide more insights into the benefits and unintended consequences of potential regulations. Conclusions: Relative to existing e-cigarette cohort studies, this study methodology has some advantages, including efficient recruitment of a lower-prevalence population and collection of detailed data relevant to tobacco regulatory science (eg, device wattage). The web-based nature of the study requires several bot- and fraudulent survey taker-related risk-mitigation strategies, which can be time-intensive. When these risks are addressed, web-based cohort studies can be successful. We will continue to explore methods for maximizing recruitment efficiency, data quality, and participant retention in subsequent waves. [ABSTRACT FROM AUTHOR]

Objective: In this study, we examined emotional profiles, the pattern of intensities of evoked emotions, and the associations between emotions and openness in the use flavored e-cigarettes among adults who do not currently use e-cigarettes – younger/never smoked and older/currently smoked. Methods: We conducted an Internet experiment in women (N = 141) who do not currently use e-cigarettes. Experiment stimuli appeared as flavor names (classic tobacco, cool mint, fresh strawberry, top-shelf bourbon) and were randomly presented to participants who rated their evoked emotions using the EsSense™ Profile. Overall liking and openness to use were assessed per flavor. Seemingly unrelated regression models were constructed to determine factors associated with openness. Results: All flavors evoked greater intensities of negative emotions (disgusted, worried, and guilty) in younger/never smoked adults. The majority of the ratings on positive emotions (enthusiastic, interested, and satisfied) were positively and significantly correlated with flavor liking, whereas disgusted, was negatively correlated with flavor liking. Perceived harm was high whereas overall liking and openness were low. Flavor liking was significantly greater for “classic tobacco” in older/currently smoked (p < .001). Conclusions: Low intensities of positive emotions to flavor names suggest disinterest in e-cigarettes as a class product irrespective of flavor. [ABSTRACT FROM AUTHOR]

INTRODUCTION E-cigarettes have been steadily increasing in popularity, both as cessation methods for smoking and for recreational and social reasons. This increase in vaping may pose cardiovascular and respiratory risks. We aimed to assess respiratory symptoms in youth users of e-cigarettes and cigarettes. METHODS A retrospective survey design was utilized to assess Canadian youth aged 16-25 years. Participants were recruited from the Ontario Tobacco Research Unit Youth and Young Adult Research Registration Panel November 2020 to March 2021. A total of 3082 subjects completed the baseline survey. Of these, 2660 individuals who did not have asthma were included in the analysis. The exposure of interest was pack-equivalent years, a novel measure of vaping exposure equivalent conceptually to cigarette pack years incorporating number of puffs per day, number of days vaped per month, and number of years vaped. Respiratory symptoms were measured using the five-item Canadian Lung Health Test. Poisson regression analyses were performed while adjusting for demographic confounders, stratified by smoking status. A non-stratified model tested the interaction of status and vaping dose and the effect of vaping device used was assessed among ever vapers. Analyses controlled for demographic characteristics, use of cannabis and alcohol, and survey date. RESULTS Each additional puff year increased the rate ratio (RR) of respiratory symptoms by a factor of 11.36 (95% CI: 4.61-28.00; p<0.001) for never smokers, but among current daily smokers higher pack-equivalent years were not associated with more respiratory symptoms (RR=0.83; 95% CI: 0.23-3.11). Among current vapers, those using pod-style devices were more likely to have more respiratory symptoms (RR=1.25; 95% CI: 1.08-1.45) after adjusting for dose. CONCLUSIONS Vaping is associated with an increased risk of reporting respiratory symptoms among never smoking youth and non-daily ever cigarette smokers. Use of e-cigarettes among non-smokers should be discouraged. [ABSTRACT FROM AUTHOR]

Electronic nicotine delivery systems (ENDSs) are used by some smokers to reduce cigarette consumption, but their effectiveness is uncertain. We aimed to examine the extent to which ENDSs or a non-nicotine cigarette substitute influence tobacco-related toxicant exposure and cigarette consumption in smokers interested in smoking reduction. We did a four-arm, parallel-group, randomised controlled trial at two sites in the USA (Penn State University, Hershey, PA, and Virginia Commonwealth University, Richmond, VA). We enrolled adults aged 21–65 years who smoked more than nine cigarettes per day (for at least the past year), with exhaled CO of more than 9 parts per million at screening, who were not currently using an ENDS, and who were interested in reducing smoking but not quitting. Participants were randomised (site-specific with allocation concealment; 1:1:1:1) to receive either a cartomiser-based, pen-style ENDS (eGo-style) paired with 0, 8, or 36 mg/mL liquid nicotine (participants and researchers masked to concentration) or a non-ENDS cigarette-shaped plastic tube that delivered no nicotine or aerosol (cigarette substitute; unmasked) for 24 weeks. Conditions were chosen to reflect a range of nicotine delivery including none (cigarette substitute and 0 mg/mL ENDS), low (8 mg/mL), and cigarette-like (36 mg/mL), and all conditions were paired with smoking reduction instructions. The primary outcome was concentration of the tobacco-specific carcinogen metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL; urinary total) collected at randomisation and at 4, 12, and 24 weeks. Multiple imputation with and without covariate adjustment was used in addition to sensitivity analyses. This trial is registered with ClinicalTrials.gov , NCT02342795. Between July 22, 2015, and Nov 16, 2017, 684 individuals were screened and 520 (76%) were enrolled and randomised. 188 (36%) of 520 participants were lost to follow-up by week 24; attrition did not differ by study group (39 [30%] of 130 in the cigarette substitute group, 56 [43%] of 130 in the ENDS with 0 mg/mL nicotine group, 49 [38%] of 130 in the ENDS 8 mg/mL group, and 44 [34%] of 130 in the ENDS 36 mg/mL group). Urinary total NNAL at 24 weeks in the ENDS with 36 mg/mL nicotine group was 210·80 pg/mg creatinine (95% CI 163·03–274·42) compared with 346·09 pg/mg creatinine (265·00–455·32) in the cigarette substitute group (p=0·0061). No other significant differences between groups were observed for any time point for urinary total NNAL. Serious adverse event frequency was similar across groups (12 events in 12 participants [9%] in the ENDS with 36 mg/mL nicotine group, seven events in six participants [5%] in the 8 mg/mL group, 11 events in ten participants [8%] in the 0 mg/mL group, and 13 events in 13 participants [10%] in the cigarette substitute group), and all of these were deemed unrelated or unlikely to be related to study product use. There was one death between randomisation and 24 weeks (suicide; in the ENDS with 0 mg/mL nicotine group). Use of an ENDS with cigarette-like nicotine delivery can reduce exposure to a major pulmonary carcinogen, NNAL, even with concurrent smoking. Future ENDS trials should involve products with well characterised nicotine delivery, including those with nicotine delivery approaching that of a cigarette. National Institutes of Health, US Food and Drug Administration. [ABSTRACT FROM AUTHOR]

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

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

Objective: Electronic cigarettes (ECIGs) are battery-powered devices that emit vaporized solutions for the user to inhale. ECIGs are marketed as a less harmful alternative to combustible cigarettes. The current study examined the effects of ECIG aerosol exposure on learning and memory, expression of brain derived neurotrophic factor (BDNF), and the activity of antioxidant enzymes in the hippocampus. Methods: Male Wistar rats were exposed to ECIG aerosol, by a whole-body exposure system, 1 h/day for 1 week, 4 weeks, and 12 weeks. Spatial learning and memory were tested using the Radial Arm Water Maze (RAWM). Hippocampal BDNF protein level, and oxidative stress biomarkers (GPx, SOD, GSH, GSSG, GSH/GSSG ratio) were also assessed. Results: ECIG aerosol exposure for 4 and 12 weeks impaired both short- and long- term memory and induced reductions in the hippocampus BDNF, SOD and GPx activities, and GSH/GSSG ratio (p < 0.05). No changes in any examined biomarkers were observed after 1-week exposure to ECIG aerosol (p > 0.05). Conclusions: ECIG aerosol exposure impaired functional memory and elicited changes in brain chemistry that are consistent with reduced function and oxidative stress. [ABSTRACT FROM AUTHOR]

Objectives: Electronic cigarette (ECIG)-generated aerosol contains particulate matter with a diameter less than 2.5 microns (PM2.5). Particles of this size may be injurious to the health of those who inhale them. Few studies have assessed the relationship between ECIG aerosol PM2.5 and ECIG liquid ingredients or ECIG device power. Methods: Two studies were conducted in which participants generated aerosols with ECIGs. In one, ECIG liquids contained various vegetable glycerin/propylene glycol ratios; in the other, ECIG devices varied by electrical power output. Results: Results indicate that, in general, PM2.5 increases as the ratio of vegetable glycerin to propylene glycol increases, or as device power increases. Conclusions: Regulating ECIG PM2.5 emissions to protect non-users requires an understanding of all the factors that influence these emissions. [ABSTRACT FROM AUTHOR]

Objectives: E-cigarettes are increasingly being used by cigarette smokers as a cessation aid. In this study, we used concept mapping to identify the full spectrum of experiences of smokers who have tried vaping to quit. Methods: In 2018, adult cigarette smokers who tried vaping to quit were recruited to complete a survey and concept mapping tasks. Participants (N = 98) generated statements by responding to a prompt. Participants then sorted and rated each of the unique statements generated during brainstorming. Multidimensional scaling and hierarchical cluster analysis were used to create a map of thematic clusters describing smokers' experiences. Mean cluster ratings were compared by reported success in quitting. Results: We identified 7 clusters. Mean cluster ratings ranged from 4.81 (SD = 0.64) for Positive Attributes to a low of 3.31 (SD = 0.78) for Health Concerns. The Positive Outcomes, Positive Attributes, and Positive Relationship clusters were rated higher among those who self-reported successfully quitting relative to non-successful quitters (ps <.05). Those who did not report quitting success rated the clusters related to limitations higher than self-reported quitters (ps <.05). Conclusions: Smokers who self-reported successful quitting had more positive experiences while vaping to quit than did those who failed to quit. [ABSTRACT FROM AUTHOR]

Objectives: In this paper, we characterize the nicotine delivery profile of a variable voltage, tank-style electronic nicotine delivery system (ENDS). Methods: Ten cigarette smokers (8 men, 2 women) completed this within-subject study assessing effects of 2 device power settings (15 W, 45 W) and 3 liquid nicotine concentrations (0, 3, and 6 mg/ml) using a tank-style ENDS. Participants completed one directed (10 puffs) and one ad libitum use period for each condition, with blood sampled throughout. Results: Plasma nicotine concentration did not increase significantly at 15 W regardless of liquid nicotine concentration. At 45 W, mean plasma nicotine increased (not significantly compared to 0 mg/ml) from 2.24 ng/ml (SD = 0.2) at baseline to 3.4 ng/ml (SD = 0.6) in the 3 mg/ml condition. In the 6 mg/ml, 45 W condition, mean plasma nicotine increased significantly (compared to 0 mg/ml) from 2.0 ng/ml (SD=0) at baseline to 5.96 ng/ml (SD = 1.3) after 10 puffs. In general, puff duration and volume decreased as device power and nicotine concentration increased. Conclusions: Despite using a variable wattage, tank-style device, nicotine delivery was minimal. These results, when combined with results from other studies using tank-style devices, highlight ENDS performance heterogeneity. Regulation may play a role in standardizing ENDS nicotine delivery. [ABSTRACT FROM AUTHOR]

Electronic nicotine delivery systems (ENDS) have the potential to help smokers living with HIV/AIDS (PLWHA) to reduce harms from tobacco use. However, little is known about ENDS use among PLWHA. This study's aim was to evaluate the acceptability of two types of ENDS among PLWHA not planning to quit smoking. The study utilized a cross-over design where participants used two ENDS in a random order as smoking substitutes during two use periods separated by 7 days. Exhaled carbon monoxide (CO) was analyzed and participants reported daily cigarette and ENDS use and completed ratings on ENDS acceptability. Participants (n = 17) were a mean age of 49.1 years (SD = 8.8), were 53% white, and 59% male. All participants had controlled HIV disease status. Participants smoked a mean of 16.9 (SD = 7.9) CPD at baseline. Overall, CPD significantly decreased during both ENDS use periods (p <.01) but there were no differences in reduction between the different devices. CO decreased from baseline to follow-up only during the button-activated ENDS use period (p =.03), but there were no differences between ENDS devices. There were no significant differences in ratings of acceptability between ENDS devices. These results suggest that ENDS could be a harm reduction tool for smokers with HIV. [ABSTRACT FROM AUTHOR]

The NHLBI convened a working group on October 23, 2019, to identify the most relevant and urgent research priorities and prevailing challenges in e-cigarette or vaping product use-associated lung injury (EVALI). Experts across multiple disciplines discussed the complexities of the EVALI outbreak, identified research priorities, and recommended strategies to address most effectively its causal factors and improve diagnosis, treatment, and prevention of this disease. Many research priorities were identified, including the need to create national and international registries of patients with EVALI, to track accurately those affected and assess outcomes. The group concluded that biospecimens from subjects with EVALI are urgently needed to help define EVALI pathogenesis and that vaping has disease risks that are disparate from smoking, with the occurrence of EVALI highlighting the importance of broadening e-cigarette research beyond comparators to smoking-related diseases. [ABSTRACT FROM AUTHOR]

Objectives: Measurement of electronic cigarette (ECIG) puff topography provides an understanding of how product characteristics and user behavior affect nicotine delivery. However, mouthpiece-based topography devices may affect natural puffing behavior. This study was designed to compare ECIG topography measured by mouthpiece-based eTop computerized device and mouthpiece-free video recordings. Methods: ECIG-naïve cigarette smokers (N = 18) and ECIG-experienced users (N = 25) puffed on a standardized ECIG via eTop or conventionally; both sessions were videotaped. Following overnight abstinence, participants experienced one directed (10 puffs, 30 sec IPI) and 2 ad libitum puffing bouts. Heart rate and subjective response were measured throughout sessions. Results: No statistically significant differences between methods were observed for topography, heart rate, or abstinence-related subjective effects, and both methods were accurate and reliable. Use of a mouthpiece was perceived to alter aspects of ECIG puffing (eg, "reduce enjoyment). Conclusions: The mouthpiece-based eTop measures ECIG topography precisely as when no mouthpiece is used, and interferes minimally with subjective ECIG experience. Reliable and valid ECIG topography measurement methods are an important regulatory tool, as they can be used to understand the interplay between product design and user behavior to predict toxicant exposure. [ABSTRACT FROM AUTHOR]

Introduction: Although some smokers switch to exclusive use of electronic cigarettes (e-cigarettes), others become dual users of combustible cigarettes and e-cigarettes. Little is known about how the onset of vaping affects the use of and dependence on combustible cigarettes or total nicotine use and dependence, which may influence health-related and cessation outcomes. Using self-report data of current combustible and e-cigarette use and retrospective recall of pre-vaping smoking in a sample of dual users, the aims of this study were (1) to compare pre- and post-vaping number of cigarettes per day and combustible cigarette dependence; (2) to compare pre- and post-vaping total nicotine use frequency (number of vaping sessions and cigarettes smoked per day), and total nicotine dependence; and (3) to examine predictors of nicotine dependence.Methods: We used baseline data from a smoking cessation trial with 2896 dual users. Nicotine use frequency and the Heaviness of Smoking Index were used as measures of nicotine use and dependence, respectively.Results: Participants decreased cigarettes/day from pre- (M = 19.24, SD = 9.01) to post-vaping (M = 11.15, SD = 8.02, p < .0001) and combustible cigarette dependence declined from pre- (M = 3.55, SD = 1.51) to post-vaping (M = 2.11, SD = 1.60, p < .0001). Total daily nicotine use frequency increased after initiating vaping (M = 19.25, SD = 9.01 vs. M = 29.46, SD = 8.61; p < .0001), as did total nicotine dependence (M = 3.55, SD = 1.51 vs. M = 4.68, SD = 1.38; p < .0001). Hierarchical regression analyses indicated that variables associated with greater overall nicotine dependence included: younger age, lower education, more years smoking, higher pre-vaping nicotine dependence, using e-cigarettes more days per month, more puffs per vaping session, higher e-liquid nicotine concentration, and longer vaping history.Conclusions: Dual use leads to a reduction in the number of combustible cigarettes, but total nicotine use and dependence increases.Implications: In dual users, a reduction in smoking following onset of vaping may offer some harm reduction via reduction in cigarette intake. However, the increase in total nicotine use and dependence could affect the ability to quit either or both products. [ABSTRACT FROM AUTHOR]

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

Electronic cigarettes (ECIGs) are appealing in part because of the many flavors of the liquids used in them. Concerns have been raised that some ECIG liquid flavors, especially those that are sweet, are attracting otherwise nicotine-naïve youth to ECIGs. Sucralose is an artificial, non-caloric sweetener that is added to some ECIG liquids. In this study, we evaluated the toxicants, namely isomers of chloropropanols that can be produced when sucralose-containing ECIG liquid is aerosolized. An analytical separation method relying on solid-phase extraction (SPE) to isolate chloropropanols from the propylene glycol/glycerol matrix was developed. Chloropropanols were then derivatized by silylation before they were analyzed on GC-MS. The influence of different ECIG operating conditions on the generation of chloropropanols was studied by varying ECIG device design and power output and also the sucralose concentration of the liquid. Heated sucralose-containing ECIG liquids produce two toxic compounds that can be found in the resulting aerosols. The two chloropropanols, 3-monochloro-1,2-propanediol (3-MCPD), and 1,3-dichloropropanol (1,3-DCP) that were detected under all conditions were found to be correlated significantly with liquid sucralose content. Effective regulation of ECIGs will minimize user and bystander exposure to these and other ECIG toxicants. Copyright © 2019 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

Introduction: Open electronic cigarette (e-cigarette) systems are customizable by consumers and often allow for potential "unorthodox" use of the product; that is, use not as intended by the manufacturer. Little is known about the types and prevalence of unorthodox uses and how these practices are transmitted via popular social media.Methods: Monthly searches of YouTube were conducted from June through November 2016 using the following search terms: "e-cigarettes," "vaping," and "e-juice." After collecting static and dynamic data on the 150 videos identified, two coders independently coded videos for general information, unorthodox use behaviors, health claims, and production quality and characteristics for orthodox and unorthodox use. Intercoder reliability was high (Cohen's κ 0.81, p < .001).Results: One hundred fifty videos were included in the study with a total of 115 551 563 views. We identified nine categories of unorthodox uses of e-cigarettes. Unorthodox use was three times as prevalent as orthodox use. Seventy-seven percent of the unorthodox use videos included recreational e-cigarette use, 57% included modification of mechanical parts and components, and 44.6% included unorthodox substance application (dripping). There were more than twice as many social media links in videos depicting unorthodox compared to orthodox use, but the level of engagement was lower for unorthodox use.Conclusions: E-cigarette unorthodox use on YouTube is more prevalent than orthodox use, suggesting the need to further investigate the prevalence of unorthodox use among e-cigarette users and the influence of social media on consumer uptake of unorthodox and orthodox uses of e-cigarettes.Implications: The US Food and Drug Administration has regulatory authority over e-cigarettes, parts and components. Many e-cigarettes currently marketed are open systems. Closed systems may allow less manipulation and may influence the safety of these products. This study provides valuable information on ways that open system e-cigarettes are used and it can inform safety tests that can be conducted by the US Food and Drug Administration to determine whether or not these products should remain on the market. In addition, our definitions of unorthodox use can be incorporated into the Population Assessment of Tobacco on Health Study to better understand the prevalence of these behaviors. [ABSTRACT FROM AUTHOR]

Background: The capability of electronic cigarette devices (e-cigs) to deliver nicotine is key to their potential to replace combustible cigarettes. We compared nicotine delivery and subjective effects associated with the use of two classes of e-cigarettes and cigarettes. Methods: 14 e-cigarette users were instructed to vape their own e-cigarette device every 20 seconds for 10 minutes while blood was drawn at 1, 2, 4, 6, 8, 10,12, and 15 minutes after initiating vaping. Users rated withdrawal symptoms and side effects before and after vaping. E-cigarette devices were classified as first-generation (same size as cigarette, no activation button) or advanced (larger than cigarette with an activation button). Separately, 10 cigarette smokers completed a similar protocol. Fisher’s Exact Test and two-sided t-tests were used as appropriate to determine differences in outcomes between first-generation e-cigarette users, advanced e-cigarette users, and smokers. Results: Compared to first-generation devices, advanced devices were associated with greater serum nicotine Cmax (ng/ml) (11.5 v. 2.8, p = 0.0231) and greater nicotine boost (ng/ml) (10.8 v. 1.8, p = 0.0177). Overall, e-cigarettes users experienced a significant reduction in withdrawal and craving, although there were no significant differences between users of first-generation and advanced devices. Comparing e-cigarettes overall to cigarettes, cigarettes were associated with greater Cmax (25.9 v. 9.0, p = 0.0043) and greater nicotine boost (21.0 v. 8.2, p = 0.0128). Conclusions: Advanced e-cigarettes delivered significantly more nicotine than first-generation devices but less than combustible cigarettes. Overall, e-cigarette use was associated with a reduction in withdrawal and craving with no reported side effects. The wide variation in nicotine absorption from different e-cigarette devices should be considered in studies of e-cigarettes for smoking cessation. [ABSTRACT FROM AUTHOR]

Objectives: In this study, we examined the concordance of manufacturers' labeled nicotine concentration on flavored electronic cigarette (e-cigarette) liquids with lab measured nicotine concentrations and how nicotine is marketed on product labels. Methods: The top 10 selling flavored e-cigarette liquids for 7 brands were purchased from 7 vape shops in 2 major US cities - Richmond, Virginia and Honolulu, Hawaii, in 2015. We examined the nicotine concentration using liquid chromatography mass spectrometry (.05mg/mL limit of quantification) and descriptive information on the e-cigarette bottles (N = 40). Results: All nicotine-based samples showed discordance between the labeled and lab measured nicotine concentrations. Overall, 27% showed a higher mean level of measured nicotine, and Richmond, VA samples showed the highest levels of discordance (-60% [pipe tobacco]; 39% [green goblin]). Additionally, 90% of the 6 different types of nicotine-related warning statements indicated that the product "may" contain nicotine ("e-liquid may contain nicotine") even when the product contained nicotine. Moreover, 20% of the e-cigarette liquids included descriptors (low, medium, high nicotine). Conclusions: The findings show that e-cigarette manufacturers provided inaccurate information about nicotine on product labels. Studies are needed to determine what quality control standards are needed to protect the public from the harms of nicotine. [ABSTRACT FROM AUTHOR]

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

Objectives: Electronic cigarettes (ECIGs) use an electrically powered heating coil to aerosolize a liquid that usually contains solvents, flavorants, and nicotine. The increasing heterogeneity of ECIG devices and liquids complicates efforts to characterize their performance. We present a transdisciplinary approach to identify popular ECIGs and characterize their features using engineering analysis. Methods: A systematic assessment of website rankings, social media content, and analytic tools identified the most popular ECIG brands in 2014 and 2016. We purchased 27 products from those brands identified in 2014 and reverse-engineered them to characterize design features. Results: Of the 23 most popular ECIG brands identified in 2014, only 8 remained popular in 2016. Devices varied by heating coil dimensions and orientation relative to airflow, location of coil, pressure drop, and other variables. Model simulations indicated that these design variations can lead to 50% or greater difference in nicotine emissions, for a given power and liquid. Power ranged from 2 to 7 Watts (W). Mean total and free-base liquid nicotine concentration was 12.16 and 9.35 (4.84) mg/ml, respectively, and PG/VG (vol/vol) ratio 61/39. Conclusions: This study demonstrates a means for tracking the evolution of ECIGs and highlights variable design features of this product relevant to regulation. [ABSTRACT FROM AUTHOR]

Background: Electronic cigarettes (ECs) can influence nicotine addiction by delivering aerosolized nicotine. We investigated if nicotine from ECs is delivered to the brain β2*-nicotinic acetylcholine receptors (β2*-nAChR) and how this relates to the behavioral effects and nicotine delivery from cigarettes.Methods: Seven nicotine users participated in positron emission tomography (PET) studies with (-)-[18F]Flubatine before and after nicotine challenge with 0, 8, and 36 mg/ml nicotine in a 3.3 Volt, 1.5 Ohm EC or a standard tobacco cigarette. Craving was evaluated before and after product use.Results: Average β2*-nAChR occupancy was higher after 36 mg/ml EC challenge compared to 8 mg/ml EC at trend level. Average β2*-nAChR occupancy after tobacco cigarette smoking was 68 ± 18% and was not different compared with 8 mg/ml (64 ± 17%,) or 36 mg/ml (84 ± 3%) nicotine in EC users. Area under the curve (AUC) of blood nicotine level was higher in the cigarette smoking group compared with the 8mg/ml group (p = 0.03), but similar compared with the 36 mg/ml EC (p = 0.29). Drug craving was reduced after use of the tobacco cigarette, 8 mg/ml EC, and 36 mg/ml EC.Conclusions: In this novel investigation of EC effects at β2*-nAChRs, we show that average β2*-nAChR occupancy was higher after 36 mg/ml EC challenge compared with 8 mg/ml EC. Receptor occupancy and arterial blood nicotine levels after cigarette smoking were similar to 36 mg/ml EC use under controlled conditions. These findings suggest that the ECs studied here have abuse liability and may provide an adequate alternative nicotine delivery system for cigarette smokers.Implications: This is the first study to directly determine the neurologic effects of electronic cigarettes on human brain beta-2 nicotinic acetylcholine receptors using PET neuroimaging with (-)-[18F]Flubatine, a novel radiotracer. Our findings suggest that the e-cigarettes studied here have abuse liability and may provide an adequate alternative nicotine delivery system for cigarette smokers. [ABSTRACT FROM AUTHOR]

Objectives: We measured e-cigarettes' abuse liability compared to conventional tobacco cigarettes under flavor and message conditions amenable to regulation. Methods: Two studies used 2 x 2 within-subjects designs with factors of e-cigarette flavor (Study 1: tobacco vs menthol; Study 2: cherry vs unflavored) and message (Study 1: reduced harm vs no message; Study 2: reduced exposure to carcinogens vs no message) with cigarette smokers (N(total) = 36). Linear mixed effects models assessed abuse liability for tobacco products. Outcomes included the price after which consumption is zero (the maximum amount participants would pay for a tobacco product) from the multiple-choice procedure (MCP) and cigarette purchase task (CPT) and demand elasticity (price sensitivity) from the CPT. Results: In the MCP, the price where consumption reached zero was significantly lower in all e-cigarette conditions except tobacco flavor (message or no message) compared to cigarettes (ps < .05). Demand elasticity was significantly higher for menthol/no message and unflavored/reduced exposure message conditions relative to cigarettes (ps < .05). Conclusions: Flavors and modified risk messages included with e-cigarettes may affect e-cigarette abuse liability among smokers, suggesting regulatory pathways to influence demand for conventional and alternative tobacco products. [ABSTRACT FROM AUTHOR]

Electronic cigarettes (ECIGs) use electricity to power a heating element that aerosolizes a liquid containing solvents, flavorants, and the dependence-producing drug nicotine for user inhalation. ECIGs have evolved rapidly in the past 8 years, and the changes in product design and liquid constituents affect the resulting toxicant yield in the aerosol and delivery to the user. This rapid evolution has been accompanied by dramatic increases in ECIG use prevalence in many countries among adults and, especially, adolescents in the United States. The increased prevalence of ECIGs that deliver nicotine and other toxicants to users' lungs drives a rapidly growing research effort. This review highlights the most recent information regarding the design of ECIGs and their liquid and aerosol constituents, the epidemiology of ECIG use among adolescents and adults (including correlates of ECIG use), and preclinical and clinical research regarding ECIG effects. The current literature suggests a strong rationale for an empirical regulatory approach toward ECIGs that balances any potential ECIG-mediated decreases in health risks for smokers who use them as substitutes for tobacco cigarettes against any increased risks for nonsmokers who may be attracted to them. [ABSTRACT FROM AUTHOR]

Introduction: Electronic cigarettes e-cigarettes aerosolize a liquid solution often containing nicotine. e-cigarette nicotine delivery may be influenced by user puffing behaviors ("puff topography"). E-cigarette puff topography can be recorded using mouthpiece-based computerized systems. The present study sought to examine the extent to which these systems influence e-cigarette nicotine delivery and other e-cigarette associated acute effects under ad libitum use conditions.Methods: Plasma nicotine concentration, heart rate, and subjective effects were assessed in 29 experienced e-cigarette users using their preferred e-cigarette battery and liquid (≥12mg/mL nicotine) in two sessions differing only by the presence of a mouthpiece-based device. In both sessions, participants completed a directed e-cigarette use bout (10 puffs, 30-s interpuff interval) and a 90-min ad libitum bout. Puff topography was recorded in the session with the topography mouthpiece.Results: Plasma nicotine, heart rate, and subjective effects, aside from "Did the e-cigarette Taste Good?" were independent of topography measurement (higher mean taste ratings were observed in the no topography condition). Mean (SEM) plasma nicotine concentration following the ad libitum bout was 34.3ng/mL (4.9) in the no topography condition and 35.7ng/mL (4.3) in the topography condition. Longer puff durations, longer interpuff intervals, and larger puff volumes were observed in the ad libitum relative to the directed bout.Conclusions: E-cigarette use significantly increased plasma nicotine concentration and heart rate while suppressing abstinence symptoms. These effects did not differ when a topography mouthpiece was present. Future studies using ad libitum e-cigarette use bouts would facilitate understanding of e-cigarette toxicant yield.Implications: No prior study has examined whether mouthpiece-based topography recording devices influence e-cigarette associated nicotine delivery, heart rate, or subjective effects under ad libitum conditions or assessed ad libitum puff topography in experienced individuals using their preferred e-cigarette battery and liquid with a mouthpiece-based computerized device. E-cigarette use significantly increased plasma nicotine concentration and heart rate while suppressing abstinence symptoms. These effects did not differ when a topography mouthpiece was present. Ad libitum puff topography differed from puff topography recorded during directed puffing. These findings suggest that future studies using ad libitum use bouts would facilitate better understanding of e-cigarette toxicant yield. [ABSTRACT FROM AUTHOR]

Electronic cigarettes (ECIGs) electrically heat and aerosolize a liquid-containing propylene glycol (PG), vegetable glycerin (VG), flavorants, water, and nicotine. ECIG effects and proposed methods to regulate them are controversial. One regulatory focal point involves nicotine emissions. We describe a mathematical model that predicts ECIG nicotine emissions. The model computes the vaporization rate of individual species by numerically solving the unsteady species and energy conservation equations. To validate model predictions, yields of nicotine, total particulate matter, PG, and VG were measured while manipulating puff topography, electrical power, and liquid composition across 100 conditions. Nicotine flux, the rate at which nicotine is emitted per unit time, was the primary outcome. Across conditions, the measured and computed nicotine flux were highly correlated (r = 0.85,p< .0001). As predicted, device power, nicotine concentration, PG/VG ratio, and puff duration influenced nicotine flux (p< .05), while water content and puff velocity did not. Additional empirical investigation revealed that PG/VG liquids act as ideal solutions, that liquid vaporization accounts for more than 95% of ECIG aerosol mass emissions, and that as device power increases the aerosol composition shifts towards the less volatile components of the parent liquid. To the extent that ECIG regulations focus on nicotine emissions, mathematical models like this one can be used to predict ECIG nicotine emissions and to test the effects of proposed regulation of factors that influence nicotine flux. Copyright © 2017 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

Objective: Evaluating electronic cigarettes (ECIGs) (also called Electronic Nicotine Delivery Systems, or ENDS) in the clinical laboratory is critical to understanding their effects. However, laboratory evaluation of ECIGs can be challenging, as they are a novel, varied, and evolving class of products. The objective of this paper is to describe some methodological challenges to the clinical laboratory evaluation of ECIGs. Methods: The authors gathered information about challenges involved in the laboratory evaluation of ECIGs. Challenges were categorized and solutions provided when possible. Results: Methods used to study combustible cigarettes may need to be adapted to account for ECIG novelty and differences within the class. Challenges to ECIG evaluation can include issues related to: (1) identification of ECIG devices and liquids; (2) determination of short-term ECIG abstinence; (3) measurement of use behavior; and (4) assessment of dependence. These challenges are discussed, and some suggestions to inform ECIG evaluation using clinical laboratory methods are provided. Conclusions: Awareness of challenges and developing, validating, and reporting methods used to address them aids interpretation of results and replication efforts, thereby enhancing the rigor of science used to protect public health through appropriate, empirically-based, ECIG regulation. [ABSTRACT FROM AUTHOR]

Introduction: Electronic cigarettes (ECIGs) aerosolize a liquid that usually contains propylene glycol and/or vegetable glycerin, flavorants, and the dependence-producing drug nicotine in various concentrations. This study examined the extent to which ECIG liquid nicotine concentration is related to user plasma nicotine concentration in ECIG-naïve tobacco cigarette smokers.Methods: Sixteen ECIG-naïve cigarette smokers completed four laboratory sessions that differed by the nicotine concentration of the liquid (0, 8, 18, or 36 mg/ml) that was placed into a 1.5 Ohm, dual coil "cartomizer" powered by a 3.3V battery. In each session, participants completed two, 10-puff ECIG use bouts with a 30-second inter-puff interval; bouts were separated by 60 minutes. Venous blood was sampled before and after bouts for later analysis of plasma nicotine concentration; puff duration, volume, and average flow rate were measured during each bout.Results: In bout 1, relative to the 0mg/ml nicotine condition (mean = 3.8 ng/ml, SD = 3.3), plasma nicotine concentration increased significantly immediately after the bout for the 8 (mean = 8.8 ng/ml, SD = 6.3), 18 (mean = 13.2 ng/ml, SD = 13.2), and 36 mg/ml (mean = 17.0 ng/ml, SD = 17.9) liquid concentration. A similar pattern was observed after bout 2. Average puff duration in the 36 mg/ml condition was significantly shorter compared to the 0mg/ml nicotine condition. Puff volume increased during the second bout for 8 and 18 mg/ml conditions.Conclusions: For a given ECIG device, nicotine delivery may be directly related to liquid concentration. ECIG-naïve cigarette smokers can, from their first use bout, attain cigarette-like nicotine delivery profiles with some currently available ECIG products.Implications: Liquid nicotine concentration can influence plasma nicotine concentration in ECIG-naïve cigarette smokers, and, at some concentrations, the nicotine delivery profile of a 3.3V ECIG with a dual coil, 1.5-Ohm cartomizer approaches that of a combustible tobacco cigarette in this population. Finding a product that delivers nicotine as effectively as a tobacco cigarette, as we report here, may be essential for smokers who want to replace completely their combustible tobacco cigarettes with ECIGs. [ABSTRACT FROM AUTHOR]

Introduction Electronic cigarettes (ECIGs) aerosolise a liquid that usually contains propylene glycol and/or vegetable glycerine, flavourants and the dependenceproducing drug, nicotine, in various concentrations. This laboratory study examined the relationship between liquid nicotine concentration and plasma nicotine concentration and puffing behaviour in experienced ECIG users. Methods Sixteen ECIG-experienced participants used a 3.3-Volt ECIG battery attached to a 1.5-Ohm dual-coil 'cartomiser' loaded with 1 mL of a flavoured propylene glycol/vegetable glycerine liquid to complete four sessions, at least 2 days apart, that differed by nicotine concentration (0, 8, 18 or 36 mg/mL). In each session, participants completed two 10-puff ECIG-use bouts (30 s puff interval) separated by 60 min. Venous blood was sampled to determine plasma nicotine concentration. Puff duration, volume and average flow rate were measured. Results Immediately after bout 1, mean plasma nicotine concentration was 5.5 ng/mL (SD=7.7) for 0 mg/mL liquid, with significantly (p<0.05) higher mean concentrations observed for the 8 (mean=17.8 ng/mL, SD=14.6), 18 (mean=25.9 ng/mL, SD=17.5) and 36 mg/mL (mean=30.2 ng/mL; SD=20.0) concentrations; a similar pattern was observed for bout 2. For bout 1, at 36 mg/mL, the mean post- minus pre-bout difference was 24.1 ng/mL (SD=18.3). Puff topography data were consistent with previous results and revealed few reliable differences across conditions. Discussion This study demonstrates a relationship between ECIG liquid nicotine concentration and user plasma nicotine concentration in experienced ECIG users. Nicotine delivery from some ECIGs may exceed that of a combustible cigarette. The rationale for this higher level of nicotine delivery is uncertain. [ABSTRACT FROM AUTHOR]

Background: This study is a systematic evaluation of a novel tobacco product, electronic cigarettes (ECIGs) using a two-site, four-arm, 6-month, parallel-group randomized controlled trial (RCT) with a follow-up to 9 months. Virginia Commonwealth University is the primary site and Penn State University is the secondary site. This RCT design is important because it is informed by analytical work, clinical laboratory results, and qualitative/quantitative findings regarding the specific ECIG products used.Methods: Participants (N = 520) will be randomized across sites and must be healthy smokers of >9 cigarettes for at least one year, who have not had a quit attempt in the prior month, are not planning to quit in the next 6 months, and are interested in reducing cigarette intake. Participants will be randomized into one of four 24-week conditions: a cigarette substitute that does not produce an inhalable aerosol; or one of three ECIG conditions that differ by nicotine concentration 0, 8, or 36 mg/ml. Blocked randomization will be accomplished with a 1:1:1:1 ratio of condition assignments at each site. Specific aims are to: characterize ECIG influence on toxicants, biomarkers, health indicators, and disease risk; determine tobacco abstinence symptom and adverse event profile associated with real-world ECIG use; and examine the influence of ECIG use on conventional tobacco product use. Liquid nicotine concentration-related differences on these study outcomes are predicted. Participants and research staff in contact with participants will be blinded to the nicotine concentration in the ECIG conditions.Discussion: Results from this study will inform knowledge concerning ECIG use as well as demonstrate a model that may be applied to other novel tobacco products. The model of using prior empirical testing of ECIG devices should be considered in other RCT evaluations.Trial Registration: TRN: NCT02342795 , registered December 16, 2014. [ABSTRACT FROM AUTHOR]

Background: Awareness and use of electronic cigarettes (e-cigs) has increased significantly in the past five years, but little is known about the experiences, satisfaction, opinions and preferences of e-cigs users.Method: 1177 participants completed an online survey about their electronic cigarette preferences, of which 200 were randomly selected for analysis. The data were analyzed using both qualitative and quantitative methods.Results: Participants found the design, the ability to customize, and the quality of vapour to be the most important characteristics of the device. Participants thought the most positive aspects of e-cig use were help to quit smoking, improved overall health, and reduced cost. The negative aspects associated with its use were mainly related to side effects, such as dry mouth. When asked to explain how e-cigs were used differently than cigarettes, participants reported puffing more regularly, but taking fewer puffs per session.Conclusions: Experienced e-cig users stated that initiating e-cig use helped them to quit or reduce their conventional smoking, which they believe reduced their health risks. In comparison to cigarette smoking, e-cig users reported using their e-cig more times per day, but with fewer puffs at each use time. Users acknowledged that more research is needed to understand the safety and long-term effects of its use. They mentioned dry mouth as a common side effect and common problems with reliability of e-cigs. Understanding these views may help health professionals to assess and assist e-cig users, and in the future, may help regulators to improve quality and reduce risks. [ABSTRACT FROM AUTHOR]

Objective: Electronic cigarettes (ECIGs) have continued to gain popularity among the general public since their introduction in 2003. While all ECIGs work by heating a liquid solution into an aerosol that is then inhaled by the user, there are differences in engineering characteristics and appearance of the devices as well as how the liquid is stored and heated, its nicotine concentration, its ratio of propylene glycol and/or vegetable glycerin, and the flavorants added to the liquid. Some of the research areas previously examined with ECIGs include aerosol toxicant yield, user puffing behavior, physiological effects, subjective effects, abuse liability, and effects on smoking cessation.Conclusion: Much of this work used earlier device models that delivered very little nicotine to the user, and additional research needs to be conducted using consistent and reliable devices, assays, and methodologies in order to gain a clearer understanding of ECIGs and their implications for individual and public health. Furthermore, the effects that ECIGs have on smoking cessation and among vulnerable populations must be addressed empirically. [ABSTRACT FROM AUTHOR]

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

Electronic cigarettes (ECIGs) comprise an aerosolized nicotine delivery product category that provides consumers with probably unprecedented control over extensive features and operating conditions, allowing a wide range of nicotine yields to be obtained. Depending on the combination of such ECIG variables as electrical power input, geometry, liquid composition, and puff behavior, ECIG users can extract in a few puffs far more or far less nicotine than with a conventional combustible cigarette. These features of ECIG design and use present challenges for public health policy, central among which is the question of how to regulate nicotine delivery. In this commentary, we propose a conceptual framework intended to provide a convenient approach for evaluating and regulating the nicotine emitted from ECIGs. This framework employs nicotine flux to account for the total dose and rate at which nicotine reaches the user, 2 key factors in drug abuse liability. The nicotine flux is the nicotine emitted per puff second (e.g., mg/s) by a given ECIG design under given use conditions, and it can be predicted accurately using physical principles. We speculate that if the flux is too low, users likely will abandon the device and maintain conventional tobacco product use. Also, we speculate that if the flux is too high, individuals may suffer toxic side effects and/or the device may have higher-than-necessary abuse liability. By considering ECIG design, operation conditions, liquid composition, and puff behavior variables in combination, we illustrate how ECIG specifications can be realistically mandated to result in a target flux range. [ABSTRACT FROM AUTHOR]

Introduction: Electronic cigarettes (ECIGs) heat a nicotine-containing solution; the resulting aerosol is inhaled by the user. Nicotine delivery may be affected by users’ puffing behavior (puff topography), and little is known about the puff topography of ECIG users. Puff topography can be measured using mouthpiece-based computerized systems. However, the extent to which a mouthpiece influences nicotine delivery and subjective effects in ECIG users is unknown. Methods: Plasma nicotine concentration, heart rate, and subjective effects were measured in 13 experienced ECIG users who used their preferred ECIG and liquid (≥12mg/ml nicotine) during 2 sessions (with or without a mouthpiece). In both sessions, participants completed an ECIG use session in which they were instructed to take 10 puffs with 30-second inter-puff intervals. Puff topography was recorded in the mouthpiece condition. Results: Almost all measures of the effects of ECIG use were independent of topography measurement. Collapsed across session, mean plasma nicotine concentration increased by 16.8ng/ml, and mean heart rate increased by 8.5 bpm (ps < .05). Withdrawal symptoms decreased significantly after ECIG use. Participants reported that the mouthpiece affected awareness and made ECIG use more difficult. Relative to previously reported data for tobacco cigarette smokers using similar topography measurement equipment, ECIG-using participants took larger and longer puffs with lower flow rates. Conclusions: In experienced ECIG users, measuring ECIG topography did not influence ECIG-associated nicotine delivery or most measures of withdrawal suppression. Topography measurement systems will need to account for the low flow rates observed for ECIG users. [ABSTRACT FROM AUTHOR]

Background: Electronic cigarettes (e-cigarettes) represent an emerging public health issue. These devices deliver nicotine along with other constituents, including flavorants, via an inhalable aerosol. Their uptake is rapidly increasing in both adults and youths, primarily among current smokers. Public debate is increasing on how these devices should be regulated and used, yet only limited peer-reviewed research exists. To develop a informed policy for e-cigarettes, their effects on human behavior, physiology, and health need to be understood. Purpose: This paper describes proceedings from a National Institutes of Health–sponsored workshop, which was held in November 2013, to identify research needs related to the effects of e-cigarettes. Discussion topics included e-cigarette risks and abuse potential; the potential role for e-cigarettes in harm reduction and smoking cessation; unintended consequences of e-cigarette use, such as becoming a gateway to conventional cigarettes; and dual use of both e-cigarettes and conventional cigarettes. Results and Conclusions: The research needs identified by the workshop participants included the following: standards to measure the contents and emissions of e-cigarettes; biomarkers of exposure; physiological effects of e-cigarettes on tissues and organ systems, including pulmonary and cardiovascular; information on e-cigarette users, how the devices are used, and identification of the best tools to assess these measures; factors that drive use and influence patterns of use; and appropriate methods for evaluating a potential role for e-cigarettes in smoking or nicotine cessation. To understand fully the challenges and the opportunities that e-cigarettes represent, expertise will be needed in basic, behavioral, translational, and clinical sciences. [ABSTRACT FROM AUTHOR]