OBJECTIVE: Disposable electronic cigarette (e-cigarette) use is becoming more popular among US youth, given the shifting landscape in product marketing, availability and regulation. This study aimed to estimate the prevalence of and test factors associated with the most used e-cigarette product (disposable versus other) among US youth aged 9-18 years who currently use e-cigarettes.
METHODS: This was an observational study using cross-sectional data from the US-based 2021 and 2022 National Youth Tobacco Surveys (n = 48 704). We restricted our analytical sample to youth who currently use e-cigarettes (n = 4137). The sample ranged from 9 to 18 years old and was 53.0% female.
METHODS: We dichotomized e-cigarette device type to disposable versus all other types (e.g. refillable pods/cartridges). We conducted logistic regression to estimate whether age, sex, race/ethnicity, sexual orientation, frequency of e-cigarette use, nicotine vaping, flavored e-cigarette use and current combustible/non-combustible tobacco use were associated with disposable e-cigarette use, compared with other e-cigarette use.
RESULTS: Among youth who currently use e-cigarettes, 54.5% used disposable e-cigarettes. Older age (17-18 years), relative to younger age (9-14 years) [odds ratio (OR) = 1.43, 95% confidence interval (CI) = 1.07-1.91], non-Hispanic Black (versus non-Hispanic White) race/ethnicity (OR = 1.47, 95% CI = 1.01-2.15), any nicotine (versus non-nicotine) vaping (OR = 2.51, 95% CI = 1.96-3.23) and flavored (versus non-flavored) e-cigarette use (OR = 1.93, 95% CI = 1.46-2.56) were associated with increased odds of mainly using disposable e-cigarettes, compared with using other e-cigarette products, whereas current combustible tobacco use (versus non-current) (OR = 0.65, 95% CI = 0.53-0.80) and current non-combustible tobacco use (versus non-current) (OR = 0.58, 95% CI = 0.43-0.78) were associated with lower odds.
CONCLUSIONS: Disposable e-cigarettes appear to be the most used type of e-cigarette product among US youth. Older age, non-Hispanic Black race/ethnicity, nicotine vaping and flavored e-cigarette use are associated with mainly using disposable e-cigarettes, relative to other e-cigarette products.

The emerging concern about chemicals in electronic cigarettes, even those without nicotine, demands the development of advanced criteria for their exposure and risk assessment. This study aims to highlight the sensitivity of lung nuclear receptors (NRs) to electronic cigarette e-liquids, independent of nicotine presence, and the influence of the sex variable on these effects. Adult male and female C57BL/6J mice were exposed to electronic cigarettes with 0%, 3%, and 6% nicotine daily (70 mL, 3.3 s, 1 puff per min/30 min) for 14 days, using the inExpose full body chamber (SCIREQ). Following exposure, lung tissues were harvested, and RNA extracted. The expression of 84 NRs was determined using the RT2 profiler mRNA array (Qiagen). Results exhibit a high sensitivity to e-liquid exposure irrespective of the presence of nicotine, with differential expression of NRs, including one (females) and twenty-four (males) in 0% nicotine groups compared to non-exposed control mice. However, nicotine-dependent results were also significant with seven NRs (females), fifty-three NRs (males) in 3% and twenty-three NRs (female) twenty-nine NRs (male) in 6% nicotine groups, compared to 0% nicotine mice. Sex-specific changes were significant, but sex-related differences were not observed. The study provides a strong rationale for further investigation.

BACKGROUND: There is only limited information about the health effects of regular vaping. Research on the health status of people who used to smoke faces the challenge that previous smoking may have caused unknown health effects. Only studies of people who vape but have never smoked combustible cigarettes can enable the detection of harms attributable to vaping. Large prospective studies of well-characterized electronic cigarette users with and without a history of combustible cigarette smoking are warranted to establish the long-term effects of regular vaping on respiratory health.
OBJECTIVE: We will conduct a global cross-sectional survey of individuals from 6 world regions. Respiratory symptoms will be assessed using a validated questionnaire-the Respiratory Symptom Experience Scale (RSES). Current vapers who are nonusers of other tobacco or nicotine products will be compared with matched controls who are nonusers of vapes and other tobacco or nicotine products.
METHODS: This will be a multicountry, cross-sectional internet-based survey of 750 adults aged ≥18 years who satisfy the criteria for inclusion in either a cohort of people who exclusively vape and who are nonusers of other tobacco or nicotine products (\"vapers cohort\"; target N=500) or a cohort of nonvapers who are also nonusers of other tobacco or nicotine products (\"controls cohort\"; target N=250). The primary end point of the study is the RSES score. RSES scores of people in the \"vapers cohort\" will be compared with those of people in the \"controls cohort.\" Additionally, the study will collect data to characterize patterns of vaping product use among the vapers cohort. Data collection will include information about the age initiation of using vape products, reasons for starting and continuing the use of vape products, specific types of products used, flavors and nicotine strengths of recently used products, as well as the frequency and intensity of product use in the past 30 days.
RESULTS: Participant recruitment started in April 2023, and enrollment was completed by November 2023 with 748 participants. Results will be reported in 2024.
CONCLUSIONS: This will be the first study providing key insights into respiratory health effects associated with using electronic cigarettes in people who vape with no established use of combustible cigarettes or other tobacco or nicotine products.
UNASSIGNED: DERR1-10.2196/54236.

BACKGROUND: The purpose of this study is to examine the use of electronic cigarettes (e-cigarettes) among college students in Hangzhou, and to analyze the influencing factors of their intention to use e-cigarettes.
METHODS: Using a stratified cluster sampling method, 775 students from two universities in Hangzhou were selected for an on-site questionnaire survey from March to April 2022. Adjusted logistic regression analysis was conducted on the influencing factors of use intention, based on innovation diffusion theory.
RESULTS: Within our sample of college students, 16.5% of students had tried e-cigarettes; 6.32% had used e-cigarettes in the past month, and 8.0% had the intention to use e-cigarettes. There were significant differences in willingness to use e-cigarettes among different genders, economic status, smoking status of close friends around them, and their own use of tobacco and alcohol (p<0.05). The logistic regression model showed that the observability of e-cigarettes (AOR=1.28; p<0.05), personal factors (AOR=1.39; p<0.05), and social systems (AOR=1.63; p<0.05), were all influencing factors of intention to use e-cigarettes.
CONCLUSIONS: College students in Hangzhou have a high intention to use e-cigarettes, and the impacts of the product itself, individual characteristics and the living environment are crucial. It is necessary to strengthen the promotion of tobacco knowledge at the social and family levels to reduce the occurrence of vaping.

BACKGROUND: Prior studies have demonstrated that the e-cigarette market contains a large number of brands. Identifying these existing e-cigarette brands is a key element of market surveillance, which will further assist in policy making and compliance checks.
OBJECTIVE: To facilitate the surveillance of the diverse product landscape in the e-cigarette market, we constructed a semantic database of e-cigarette brands that have appeared in the US market as of 2020-2022.
METHODS: In order to build the brand database, we searched and compiled e-cigarette brands from a comprehensive list of retail channels and sources, including (1) e-liquid and disposable brands sold in web-based stores, (2) e-cigarette brands sold in brick-and-mortar stores and collected by the Nielsen Retail Scanner Data, (3) e-cigarette brands compiled by Wikipedia, (4) self-reported e-cigarette brands from the 2020 International Tobacco Control Four-Country Smoking and Vaping (ITC 4CV) US survey, and (5) e-cigarette brands on Twitter. We also estimated the top 5 e-cigarette brands by sales volume in brick-and-mortar stores, by the frequency and variety of offerings in web-based shops, and by the frequency of self-reported brands from the 2020 ITC 4CV US survey.
RESULTS: As of 2020-2022, a total of 912 e-cigarette brands have been sold by various retail channels. During 2020-2022, the top 5 brands are JUUL, vuse, njoy, blu, and logic in brick-and-mortar stores; blu, king, monster, twist, and air factory for e-liquids in web-based stores; hyde, pod mesh, suorin, vaporlax, and xtra for disposables sold in web-based stores; and smok, aspire, vaporesso, innokin, and eleaf based on self-reported survey data.
CONCLUSIONS: As the US Food and Drug Administration enforces the premarket tobacco market authorization, many e-cigarette brands may become illegal in the US market. In this context, how e-cigarette brands evolve and consolidate in different retail channels will be critical for understanding the regulatory impacts on product availability. Our semantic database of e-cigarette brands can serve as a useful tool to monitor product and marketplace development, conduct compliance checks, assess manufacturers\' marketing behaviors, and identify regulatory impacts.

[This corrects the article DOI: 10.3389/fchem.2023.1212744.].

BACKGROUND: Over the last decade, the use of electronic nicotine delivery systems (ENDSs) has risen, whereas studies that describe how consumers use these products have been limited. Most studies related to ENDS use have involved study designs focused on use in a central location environment or attempted to measure use outcomes through subjective self-reported end points. The development of accurate and reliable tools to collect data in a naturalistic real-world environment is necessary to capture the complexities of ENDS use. Using connected devices in a real-world setting provides a convenient and objective approach to collecting behavioral outcomes with ENDS.
OBJECTIVE: The Product Use and Behavior instrument was developed and used to capture the use of the Vuse Solo ENDS in an ambulatory setting to best replicate real-world use behavior. This study aims to determine overall mean values for topography outcomes while also providing a definition for an ENDS use session.
METHODS: A prospective ambulatory clinical study was performed with the Product Use and Behavior instrument. Participants (n=75) were aged between 21 and 60 years, considered in good health, and were required to be established regular users of ENDSs. To better understand use behavior within the population, the sample was sorted into percentiles with bins based on daily puff counts. To frame these data in the relevant context, they were binned into low-, moderate-, and high-use categories (10th to 40th, 40th to 70th, and 70th to 100th percentiles, respectively), with the low-use group representing the nonintense category, the high-use group representing the intense category, and the moderate-use group being reflective of the average consumer.
RESULTS: Participants with higher daily use took substantially more puffs per use session (6.71 vs 4.40) and puffed more frequently (interpuff interval: 32.78 s vs 61.66 s) than participants in the low-use group. Puff duration remained consistent across the low-, moderate‑, and high-use groups (2.10 s, 2.18 s, and 2.19 s, respectively). The moderate-use group had significantly shorter session lengths (P<.001) than the high- and low-use groups, which did not differ significantly from each other (P=.16).
CONCLUSIONS: Using connected devices allows for a convenient and robust approach to the collection of behavioral outcomes related to product use in an ambulatory setting. By using the variables captured with these tools, it becomes possible to move away from predefined periods of use to better understand topography outcomes and define use sessions. The data presented here offer a possible method to define these sessions. These data also begin to frame international standards used for the analytical assessments of ENDSs in the correct context and begin to shed light on the differences between standardized testing regimens and actual use behavior.
BACKGROUND: Clinicaltrials.gov NCT04226404; https://clinicaltrials.gov/study/NCT04226404.

E-cigarettes have been available for over 15 years, but relatively little is known about long-term users. Our aim was to describe change over time in behaviours, attitudes and dependence in long-term users.
A longitudinal study of 375 e-cigarette users enrolled on the Internet in 2012-2016 and surveyed again in 2021 (8 years later on average), who continuously used e-cigarettes in the interval.
Fewer people in 2021 (11 %) than at baseline (33 %) had smoked tobacco in the past 31 days. Participants switched from second-generation models at baseline (e.g. Ego) to box mods in 2021 (e.g. iStick), they used larger refill bottles, they used home-made e-liquids twice as often, they used tobacco flavours less often and the nicotine concentration in e-liquids decreased from 12 to 6 mg/mL. There was no change over time in the time to the first e-cigarette puff of the day, but an e-cigarette dependence score of 0-100 decreased from 75 to 60, the frequency and strength of urges to vape decreased (from 31 % to 18 % of \"strong\" urges) and the proportion of people who said they would be likely to succeed if they tried to stop vaping increased. Compared to baseline, fewer people in 2021 reported vaping to cope with cravings or other smoking cessation symptoms, and fewer people reported vaping to quit smoking, to avoid relapse into smoking, or to reduce their tobacco consumption (p < 0.001 for all differences).
In long-term, continuous users, over a period of 8 years, substantial changes were observed in the models of e-cigarettes used, in the flavours and strength of e-liquids, and in the reasons for vaping. Their level of nicotine dependence tended to decrease over time. These users were satisfied with e-cigarettes and vaped mostly because they felt that vaping was less dangerous than smoking, and for enjoyment.

CONCLUSIONS: Dual EC/CC users had a significantly greater risk of CRS or FESS when compared to solo users. Dual EC/CC users did not have a significantly greater risk of polyposis when compared to solo users. This effect likely relates to bacterial, immune cell, genetic, and mucociliary alterations.

Leachable investigations are routinely undertaken across a range of sectors (e.g., pharmaceuticals, medical devices, etc.) to determine whether chemicals from a container closure system transfer into a product under normal conditions of use. For Electronic Nicotine Delivery Systems (ENDS) the container closure system includes all materials in contact with the e-liquid that is aerosolized and subsequently inhaled by the user. Currently, there is no guidance for conducting leachable studies for ENDS products, however, there are relevant guidance documents for orally inhaled drug products that can be applied to an ENDS container closure system. We present a case study of the analytical investigation of two leachable compounds identified in simulated leachable studies using aged JUULpods filled with unflavored e-liquid (PG/VG/nicotine/benzoic acid). Both compounds had limited toxicological information and were considered data deficient. A qualitative analysis of the aerosol collected from aged commercial JUULpods (Virginia Tobacco and Menthol), using a similar analytical method (LC-MS/MS) used in the simulated leachable studies, showed no trace or detectable levels of either leachable compound. Therefore, this qualitative analysis did not provide semi-quantitative values for the data-deficient leachable compounds necessary to support toxicological risk assessment. Further, no commercial authentic standards or reasonable synthetic route were available due to the molecular size and structural complexity of the compounds. Instead, method limits were established using an alternative approach to standard ICH guidelines. The experimentally determined method limit of quantitation, using spiked samples of simulated leachable e-liquid, provided conservative semi-quantitative values for each data deficient leachable compound in the aerosol that enabled a transfer efficiency from e-liquid to aerosol to be estimated. The transfer efficiency of each leachable compound was experimentally determined to be less than 2% based on the limit of quantitation, which then could be used to define a relevant exposure limit for the toxicological risk assessment. This work details a novel analytical approach for determining the transfer efficiency of data deficient leachable compounds from ENDS container closure systems into the ENDS aerosol to support toxicological health risk assessments.