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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]

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]

Objectives: We evaluated urine propylene glycol (PG) and vegetable glycerin (VG) as potential markers for discriminating e-cigarette (ECIG) users and non-users and verifying ECIG abstinence. Methods: We analyzed urine samples from 51 ECIG users (collected pre-/post-12-hour ECIG abstinence), and 50 controls (nicotine/tobacco non-users) urine cotinine, PG, and VG concentration. Results: Of 42 ECIG users with pre-abstinence urine cotinine indicating nicotine use, mean (SD) urine cotinine concentration was 1053.7 ng/ml (874.5) and for controls was 1.93 ng/ml (0.4); after abstinence, ECIG users' mean cotinine decreased to 615.4 ng/ml (753.0). For ECIG users, mean urine PG pre-abstinence was 25.6 mcg/ml (20.0) and was 9.8 mcg/ml (13.5) for controls; after abstinence, ECIG users' mean urine PG decreased to 9.7 mcg/ml (15.0; ps < .05). For ECIG users, mean urine VG pre-abstinence was 7.5 mcg/ml (7.1) and was 13.2 mcg/ml (25.0) for controls; after abstinence, ECIG users' mean VG decreased to 5.0 mcg/ml (4.4; ps < .05). Conclusions: ECIG users' mean urine PG was greater than controls and decreased after 12-hour ECIG abstinence suggesting urine PG may be useful for discriminating ECIG users from non-users and verifying short-term abstinence. [ABSTRACT FROM AUTHOR]

Objectives: The province of Ontario, Canada banned menthol in cigarettes and other tobacco products effective January 1, 2017 thereby adding to an existing flavor ban. However, there was an exemption for all flavored e-cigarettes, flavored cigars larger than 6 grams, and alcohol flavored cigars without filters over 1.4 grams. In this paper, we examine the association between use of flavored non-cigarette products and self-reported cigarette smoking cessation after the ban. Methods: We recruited current past-30 day cigarette smokers (N = 913) who were 16 years or older and living in Ontario during September-December 2016 and re-contacted January-August 2018. Results: Both daily and occasional pre-ban menthol cigarette smokers were more likely to use flavored cigar products (adjusted relative rate, RR = 1.53, 95% confidence interval, CI = 1.01, 2.31; adjusted RR = 1.57, 95% CI = 1.06, 2.30) after the ban, while occasional pre-ban menthol cigarette smokers were more likely to use other tobacco products (adjusted RR = 1.25, 95% CI = 1.02, 1.53) or flavored other tobacco products (adjusted RR = 1.56, 95% CI = 1.09, 2.24), conditional on prior use. Conclusions: Menthol smokers prior to the ban were more likely to use other tobacco products, or flavored tobacco products, after the ban. These results suggest that comprehensive menthol bans could be more effective without the option of using flavored tobacco or nicotine products as substitutes. [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]

Objective: We examined menthol cigarette smokers' reactions to Ontario's menthol cigarette ban. Methods: In April 2017, past-year adult menthol cigarette smokers from Ontario, Canada (N = 67; 64.2% women) participated in an online study. Participants generated statements describing their reactions to the ban. Researchers reviewed statements continuously until reaching content saturation, and then removed duplicate statements. Participants sorted the final 79 statements by content similarity and rated each statement from 1 (Definitely NOT true) to 7 (Definitely true). Multidimensional scaling of sorting data generated a cluster map and mean cluster ratings were compared. Results: Seven statement clusters describing reactions to the menthol ban were generated: thoughts about the ban, perceiving the ban as ineffective, emotional reactions to the ban, smoking non-menthol cigarettes, smoking cessation or reduction, alternative menthol cigarette purchasing behaviors, and alternative tobacco use behaviors. Participants rated the thoughts about the ban cluster highest (most true) and alternative tobacco use behaviors cluster lowest (least true). Participants who smoked menthol cigarettes before the ban every day or most days rated clusters higher than pre-ban occasional or rare menthol smokers. Conclusions: Banning menthol cigarettes resulted in reactions including negative feelings about the ban, smoking cessation attempts, and behaviors to find menthol cigarette alternatives. [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]

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]

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]