BACKGROUND: Electronic cigarettes (e-cigarettes) are often advertised as a safer alternative to traditional smoking. However, recent data suggest they may not be as safe as previously believed. This study aims to evaluate the genotoxicity and mutagenicity of e-cigarette liquids.
METHODS: We randomly selected eight varieties of e-cigarette liquids from the local market in Jeddah, Saudi Arabia. We evaluated their genotoxicity using the Genotoxicity SOS-Chromo Test™ Kit. In this investigation, a rat liver S9 fraction was utilized to emulate liver metabolic function to measure any chemical substance\'s mutagenic potential. The SOS-Chromo Test was performed by recording the β-galactosidase and alkaline phosphatase activity with and without the metabolic activation enzyme (S-9).
RESULTS: All samples, except for the first two dilutions of sample 2, were nongenotoxic in the absence of the S9 activation enzyme, according to the genotoxicity analysis. However, when tested in the presence of the S9 enzyme, samples 2, 4, and 7 exhibited mutagenic activity at varying concentrations.
CONCLUSIONS: Contrary to common belief, e-cigarettes are not safe. The present investigation confirms the presence of both toxicants and carcinogens in some e-cigarette liquids. This exposure could increase users\' risk of various health complications.

The purpose of this study was to determine the effect of circulating microvesicles isolated from chronic electronic (e-)cigarette users on cultured human umbilical vein endothelial cell (HUVEC) expression of nuclear factor-κB (NF-κB), cellular cytokine release, phosphorylation of endothelial nitric oxide synthase (eNOS) and NO production. The HUVECs were treated with microvesicles isolated via flow cytometry from nine non-tobacco users (five male and four female; 22 ± 2 years of age) and 10 e-cigarette users (six male and four female; 22 ± 2 years of age). Microvesicles from e-cigarette users induced significantly greater release of interleukin-6 (183.4 ± 23.6 vs. 150.6 ± 15.4 pg/mL; P = 0.002) and interleukin-8 (160.0 ± 31.6 vs. 129.4 ± 11.2 pg/mL; P = 0.01), in addition to expression of p-NF-κB p65 (Ser536) (18.8 ± 3.4 vs. 15.6 ± 1.5 a.u.; P = 0.02) from HUVECs compared with microvesicles from non-tobacco users. Nuclear factor-κB p65 was not significantly different between microvesicles from the non-tobacco users and from the e-cigarette users (87.6 ± 8.7 vs. 90.4 ± 24.6 a.u.; P = 0.701). Neither total eNOS (71.4 ± 21.8 vs. 80.4 ± 24.5 a.u.; P = 0.413) nor p-eNOS (Thr495) (229.2 ± 26.5 vs. 222.1 ± 22.7 a.u.; P = 0.542) was significantly different between microvesicle-treated HUVECs from non-tobacco users and e-cigarette users. However, p-eNOS (Ser1177) (28.9 ± 6.2 vs. 45.8 ± 9.0 a.u.; P < 0.001) expression was significantly lower from e-cigarette users compared with non-tobacco users. Nitric oxide production was significantly lower (8.2 ± 0.6 vs. 9.7 ± 0.9 μmol/L; P = 0.001) in HUVECs treated with microvesicles from e-cigarette users compared with microvesicles from non-tobacco users. This study demonstrated increased NF-κB activation and inflammatory cytokine production, in addition to diminished eNOS activity and NO production resulting from e-cigarette use. HIGHLIGHTS: What is the central question of this study? Circulating microvesicles contribute to cardiovascular health and disease via their effects on the vascular endothelium. The impact of electronic (e-)cigarette use on circulating microvesicle phenotype is not well understood. What is the main finding and its importance? Circulating microvesicles from e-cigarette users increase endothelial cell inflammation and impair endothelial nitric oxide production. Endothelial inflammation and diminished nitric oxide bioavailability are central factors underlying endothelial dysfunction and, in turn, cardiovascular disease risk. Deleterious changes in the functional phenotype of circulating microvesicles might contribute to the reported adverse effects of e-cigarette use on cardiovascular health.

BACKGROUND: Electronic nicotine delivery systems (ENDS) offer a promising approach to tobacco harm reduction, but many people use both ENDS and combustible cigarettes (\"dual use\"), which undermines potential risk reduction. To explore the role of ENDS nicotine delivery in promoting switching to ENDS, we conducted a study in which people who smoked cigarettes were offered an ENDS that had previously been shown to replicate the rapid nicotine pharmacokinetics of combustible cigarettes (BIDI® Stick).
METHODS: Twenty-five cigarette smoking adults, not seeking smoking cessation treatment, but open to using ENDS as a cigarette substitute, were provided with a 12-week supply of BIDI® Stick in tobacco or menthol flavors, during a study that included seven biweekly sessions and a 6-month follow-up. Daily diaries assessed ENDS and cigarette use, and exhaled carbon monoxide (eCO) served as an objective marker of smoke intake. Subjective ratings were collected to assess the rewarding properties of ENDS and combustible cigarettes, and indices of nicotine dependence.
RESULTS: Over 12 weeks, ENDS use increased to an average of 15.8 occasions per day (SD = 20.2) and self-reported cigarette consumption decreased by 82% from 16.7 cigarettes/day (SD = 6.0) at baseline to 3.0 cigarettes/day (SD = 4.1) at week 12. The eCO level decreased by 27% from an average of 20.0 ppm (SD = 9.8) at baseline to 14.5 ppm (SD = 9.9) at week 12. Four of 25 participants completely switched to ENDS and were smoking abstinent during weeks 9-12. At 6 months one participant was confirmed to be abstinent. Ratings of subjective reward for the ENDS were very similar to those of participants\' usual brands of cigarettes. Dependence level was lower for the ENDS than for combustible cigarettes.
CONCLUSIONS: In this study, the ENDS effectively replicated the subjective rewarding effects of participants\' usual brands of cigarettes and led to a substantial reduction in reported cigarettes/day. Exhaled CO showed less of a decrease, possibly due to compensatory smoking behavior and/or the timing of eCO measurements that might not have reflected smoke intake throughout the day. The relatively low rate of sustained smoking abstinence at 6 months suggests that additional approaches continue to be needed for achieving higher rates of complete switching.
BACKGROUND: ClinicalTrials.gov identifier NCT05855343.

UNASSIGNED: E-cigarettes are the most-used nicotine product among adolescents, but limited psychometrically-sound, e-cigarette-relevant measures exist for adolescents. We examined psychometric properties of the Self-Report Habit Index (SRHI) for assessing adolescents\' habitual e-cigarette use.
UNASSIGNED: During Fall 2022, 4855 students from eight Connecticut high schools completed an anonymous survey. The analytic sample comprised 491 students who reported past-month e-cigarette use and completed the SRHI (Age M=15.94, SD=1.24 years, 56 % female, 37.1 % Hispanic, 57.6 % White). We examined the SRHI\'s latent factor structure; internal reliability; measurement invariance and between-groups differences (e.g., nicotine vs. nicotine-free vaping); and associations with total e-cigarette flavors used in the past month, past-30-day vaping frequency, and e-cigarette dependence.
UNASSIGNED: The SRHI\'s 6-item, 1-factor structure was confirmed. Internal reliability was excellent. The SRHI was scalar invariant for all subgroups tested. Nicotine (vs. nicotine-free) and daily (vs. non-daily) e-cigarette use were associated with greater habitual e-cigarette use behavior. In adjusted models, habitual e-cigarette use was associated with using more e-cigarette flavors, vaping more frequently, and greater e-cigarette dependence. Habitual e-cigarette use incrementally accounted for variance in past-month flavors used and vaping frequency beyond dependence.
UNASSIGNED: The SRHI evidenced solid psychometric properties for assessing habitual e-cigarette use behavior among high school students. Relationships between habitual use and frequency of use, e-cigarette flavors, and dependence might be expected as these constructs are associated with the three characterizing features of habitual behaviors: frequent repetition, cue-driven elicitation, and automaticity. Future prospective research can clarify the temporal ordering of habitual e-cigarette use and dependence in adolescents.

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.

Understanding the correlation between demographic, socio-economic, and lifestyle factors with e-cigarette use, cigarette smoking, and dual use is essential for targeted public health interventions. This study examines the prevalence of these behaviors in Scotland and identifies the associated factors. We conducted a repeated cross-sectional analysis of the Scottish Health Survey data from 2017 to 2021, leveraging data from 12,644 participants aged 16 and older: 2271 cigarette smokers, 687 e-cigarette users, 428 dual users, and 9258 never users. Weighted prevalences were calculated by age group, sex, and survey year, followed by weighted multinomial logistic regression to explore associated factors. The overall prevalences were 72.0% (95% CI 70.9-73.1) for never users, 18.9% (95% CI 17.9-19.9) for cigarette smokers, 5.5% (95% CI 5.0-6.1) for e-cigarette users, and 3.6% (95% CI 3.2-4.0) for dual users. From 2017 to 2021, cigarette smoking declined from 21.7% (95% CI 19.6-23.9) to 13.1% (95% CI 11.5-15.0), e-cigarette use from 6.5% (95% CI 5.4-7.8) to 4.8% (95% CI 3.6-6.4), and dual use from 3.7% (95% CI 2.9-4.6) to 2.7% (95% CI 1.9-3.7). Age was a critical factor, with the 25-34 age group more likely to use e-cigarettes (p = 0.007) and the 35-44 age group more likely to engage in dual use (p = 0.006) compared to the 16-24 age group. Males had higher odds of e-cigarette use than females (p = 0.031). White individuals had higher odds of using e-cigarettes (p = 0.023) and being dual users (p = 0.017) compared to non-whites. Previously married individuals had higher odds of dual use than singles (p = 0.031). Larger household sizes were linked to reduced odds of all three behaviors (p = 0.001). Rural residents were less likely to use e-cigarettes compared to urban residents (p = 0.025). Higher education correlated with lower odds of all three behaviors (p = 0.001). Manual occupation increased the likelihood of dual use (p = 0.042). Lower income and higher deprivation significantly increased the odds of all three behaviors (p < 0.001). Excessive alcohol consumption was associated with increased odds of the three behaviors (p < 0.001). Poor sleep quality correlated with increased odds of dual use (p = 0.002) and cigarette smoking (p < 0.001). Adherence to physical activity guidelines was associated with reduced odds of all three behaviors (cigarette smoking p < 0.001, e-cigarette use p = 0.031, dual use p = 0.016). In conclusion, this study showed a decline in the prevalence of cigarette smoking, e-cigarette use, and dual usage from 2017 to 2021 in Scotland. Significant associations with demographic, socio-economic, and lifestyle factors highlight the need for targeted public health interventions.

BACKGROUND: Electronic cigarettes (ECs) have been promoted as alternatives to traditional cigarettes.
OBJECTIVE: To investigate ECs\' effects on respiratory system, especially in patients with respiratory diseases.
METHODS: We randomly selected 25 smokers with stable moderate asthma and matched them with 25 healthy smokers. All were subjucted to pulmonary function tests (PFTs), impulse oscillometry (IOS), fraction exhaled Nitric Oxide (FeNO), exhaled breathe condensate (EBC) and biomarker measurements before and after vaping one nicotine-containing EC.
RESULTS: The increase in FeNO 30 minutes after EC, reflecting airway inflammation, significantly correlated with increase of residual volume (RV), total lung capacity, respiratory impedance at 5 Hz (Z5Hz) and respiratory resistance at 5 and 20 Hz (R5Hz and R20Hz). No significant correlations were found between EBC biomarkers\' changes and respiratory mechanics.
CONCLUSIONS: This is the first study demonstrating that the changes in airway inflammation caused by EC have direct effects in respiratory mechanics of asthmatic patients.

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.

OBJECTIVE: In Finland, nicotine pouches entered the national market abruptly in 2023, following a change in April 2023 from medicinal product classification into less regulated tobacco surrogate status. This study aimed to measure adolescent nicotine pouch use and associated characteristics.
METHODS: A cross-sectional, nationwide school-based survey among students in comprehensive schools (COMP), general upper secondary schools (GEN) and vocational institutes (VOC) in 2023 in Finland.
METHODS: A total of 151 224 respondents aged 14-20 years (mean age 16.18 years, standard deviation 1.20 years).
METHODS: Nicotine pouch use was used as the outcome variable. Demographics included age, sex, school type and tobacco product use (smoking, snus use and e-cigarette use). Covariates included parental education and parental smoking. All measures were self-reported.
RESULTS: Unadjusted results showed that current nicotine pouch use was more common among boys (11.3%) than among girls (3.3%), adolescents in VOC (15.4%) compared with COMP (6.8%) and GEN (4.3%), whereas daily use of other tobacco and nicotine products was associated with current nicotine pouch use compared with never using such products and the association was especially strong for snus use. The fully adjusted estimates of current nicotine pouch use remained strong for daily use of other tobacco and nicotine products (snus use: adjusted prevalence ratio [aPR] = 74.95, 95% confidence interval [CI] = 65.65-84.25; smoking: aPR = 1.43, 95% CI = 1.36-1.50; e-cigarette use: aPR = 2.15, 95% CI = 2.04-2.27) and for sex (boys aPR = 1.53, 95% CI = 1.48-1.57). There was no clear evidence of differences in current nicotine pouch use by school type, age or parental factors in the fully adjusted model.
CONCLUSIONS: In Finland in 2023, during which the availability of nicotine pouches became less regulated, nicotine pouch use appeared to be more common among boys and adolescents who used other nicotine products.

OBJECTIVE: The primary objective of this in vitro experiment was an assessment of proliferative capacity, metabolic activity, and potential cellular detriment of human periodontal ligament cells (hPDL) exposed to cigarette smoke (CS), electronic cigarette vapor (eCV), and heated tobacco product aerosol (HTP), or air (control).
METHODS: Using a CAD/CAM-designed exposition chamber, hPDL were exposed to CS, eCV, HTP, or air (control) based on the Health Canada Intense Smoking Regime. Cell proliferation, metabolic activity, and cellular detriment were assessed at various time points.
RESULTS: Compared to the control, hPDL exposed to CS exhibited significantly decreased cell numbers at all time points. HTP exposure led to reduced cell numbers 48 h and 72 h post-exposure, while eCV-exposed cells showed no significant decrease. The metabolic activity of eCV-treated hPDL was slightly reduced at 7 h but recovered at 24 h and 48 h. In contrast, CS-treated cells exhibited significantly decreased metabolic activity at 24 h and 48 h, and HTP-exposed cells showed a significant decrease after 48 h. Flow cytometry indicated both apoptotic and necrotic cell death following CS exposure, with necrotic cell death being more pronounced.
CONCLUSIONS: eCV and HTP demonstrated comparatively reduced detrimental effects on hPDL compared to CS.
CONCLUSIONS: The findings suggest that conventional cigarette smoke poses a substantial risk to periodontal health by significantly impairing cell proliferation and metabolic activity. However, alternatives such as eCV and HTP may offer a comparatively reduced risk.