Exposure to Heated Tobacco Products and Adverse Health Effects, a Systematic Review

Heated tobacco product marketing: a mixed-methods study examining exposure and perceptions among US and Israeli adults

The marketing of heated tobacco products (HTPs), like IQOS, influences consumers' perceptions. This mixed-methods study analyzed (i) survey data (2021) of 2222 US and Israeli adults comparing perceptions of 7 IQOS attributes (design, technology, colors, customization, flavors, cost and maintenance) and 10 marketing messages (e.g. 'Go smoke-free…') across tobacco use subgroups and (ii) qualitative interviews (n = 84) regarding IQOS perceptions. In initial bivariate analyses, those never using HTPs (86.2%) reported the least overall appeal; those currently using HTPs (7.7%) reported the greatest appeal. Notably, almost all (94.8%) currently using HTPs also currently used cigarettes (82.0%) and/or e-cigarettes (64.0%). Thus, multivariable linear regression accounted for current cigarette/e-cigarette use subgroup and HTP use separately; compared to neither cigarette/e-cigarette use (62.8%), cigarette/no e-cigarette use (17.1%) and e-cigarette/no cigarette use (6.5%), those with dual use (13.5%) indicated greater overall IQOS appeal (per composite index score); current HTP use was not associated. Qualitative data indicated varied perceptions regarding advantages (e.g. harm, addiction and complexity) of IQOS versus cigarettes and e-cigarettes, and perceived target markets included young people, those looking for cigarette alternatives and females. Given the perceived target markets and particular appeal to dual cigarette/e-cigarette use groups, IQOS marketing and population impact warrant ongoing monitoring to inform regulation.

Cytotoxic impact of nicotine products on periodontal ligament cells

OBJECTIVES

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).

MATERIALS AND 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.

CLINICAL RELEVANCE

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.

Challenges in current inhalable tobacco toxicity assessment models: A narrative review

Emerging tobacco products such as electronic nicotine delivery systems (ENDS) and heated tobacco products (HTPs) have a dynamic landscape and are becoming widely popular as they claim to offer a low-risk alternative to conventional smoking. Most pre-clinical laboratories currently exploit in vitro, ex vivo, and in vivo experimental models to assess toxicological outcomes as well as to develop risk-estimation models. While most laboratories have produced a wide range of cell culture and mouse model data utilizing current smoke/aerosol generators and standardized puffing profiles, much variation still exists between research studies, hindering the generation of usable data appropriate for the standardization of these tobacco products. In this review, we discuss current state-of-the-art in vitro and in vivo models and their challenges, as well as insights into risk estimation of novel products and recommendations for toxicological parameters for reporting, allowing comparability of the research studies between laboratories, resulting in usable data for regulation of these products before approval by regulatory authorities.

Assessing the association between e-cigarette use and cardiovascular disease: A meta-analysis of exclusive and dual use with combustible cigarettes

BACKGROUND

Growing evidence highlights the impact of e-cigarette use on cardiovascular health, prompting a crucial examination of its association with cardiovascular disease (CVD) in both exclusive e-cigarette and dual use scenarios with combustible cigarettes. This meta-analysis assessed the association between e-cigarette use and CVD by synthesizing the existing literature.

METHODS

Pertinent observational studies were identified using multiple electronic databases, from August 22nd, 2006, to April 10th, 2024. A meta-analysis was conducted using random-effect models. Risk of bias was assessed using the National Institutes of Health (NIH) Study Quality Assessment Tools.

FINDINGS

A total of 20 observational studies involving 8,499,444 participants were included in the meta-analysis. Dual use (e-cigarettes and combustible cigarette) increased the odds of CVD by 2.56 times (95 % CI: 2.11, 3.11) compared to never use of both. Current e-cigarette use combined with former combustible cigarette increased the odds of CVD by 2.02 times (95 % CI: 1.58, 2.58) compared to never use of either. Exclusive current e-cigarette use did not show a statistically significant association with CVD odds compared to never use of either (OR = 1.24, 95 % CI: 0.93, 1.67).

CONCLUSIONS

Dual use of e-cigarettes and combustible cigarettes was significantly associated with CVD, but results failed to show a significant association between exclusive e-cigarette use and CVD. Robust and longitudinal studies are needed to understand the long-term implications of e-cigarette use and CVD. Public health efforts should focus on awareness, smoking cessation, and regulating both e-cigarettes and combustible cigarettes.

Impact of electronic cigarettes (e-cigs) and heat-not-burn/heated tobacco products (HnB/HTP) on asthma and chronic obstructive pulmonary disease: a viewpoint of the Italian Society of Internal Medicine

The association of cigarette smoking with several severe and very severe diseases (oncological, cardiovascular, respiratory) which have dramatic epidemiological, medical, and financial impact, is a well-known public threat. Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent diseases in Italy, posing significant public health challenges. Tobacco smoking, a primary risk factor for COPD and a common asthma trigger, remains a critical preventable public health issue. While universally acknowledged that quitting smoking drastically reduces the risk of smoking-related health issues, a significant portion of smokers and patients find quitting challenging or undesirable, hence a need for new ways to deal with it. A worth considering alternative might be the switch to electronic cigarettes (e-cig), and heat-not-burn/heated tobacco products (HnB/HTP). Emerging evidence suggests potential benefits in asthma and COPD management when transitioning from traditional smoking to e-cigs or HnB devices. However, the effectiveness of these products in facilitating smoking cessation is still debated, alongside concerns about their role in promoting smoking initiation among non-smokers. Internists are among the physicians who most frequently assist patients with smoking-related diseases, and in this perspective they cannot avoid paying attention to the progressive diffusion of smoking products alternative to the traditional cigarette, and to the controversies with respect to their use. In this context, the Italian Society of Internal Medicine, also recognizing a growing need for clarity for healthcare providers, has undertaken a comprehensive analysis of existing literature to offer an informed perspective on the health impact of e-cigs and HnB/HTP on asthma and COPD.

Effects of Combustible Cigarettes and Electronic Nicotine Delivery Systems on the Development and Progression of Chronic Lung Inflammation in Mice

INTRODUCTION

Although detrimental effects of combustible cigarettes (CCs) on the progression of lung inflammatory diseases are well known, changes in electronic nicotine delivery systems (ENDS)-exposed lung-infiltrated immune cells are still unrevealed.

AIMS AND METHODS

The analysis of blood gas parameters, descriptive and quantitative histology of lung tissues, determination of serum cytokines, intracellular staining, and flow cytometry analysis of lung-infiltrated immune cells were used to determine the differences in the extent of lung injury and inflammation between mice from experimental (CC and ENDS-exposed animals) and control groups (Air-exposed mice).

RESULTS

Continuous exposition to either CCs or ENDS induced severe systemic inflammatory response, increased activation of NLRP3 inflammasome in neutrophils and macrophages and enhanced dendritic cell-dependent activation of Th1 and Th17 cells in the lungs. ENDS induced less severe immune response than CCs. Serum concentrations of inflammatory cytokines were significantly lower in the samples of ENDS-exposed mice. Compared to CCs, ENDS recruited lower number of circulating leukocytes in injured lungs and had less capacity to induce CD14/TLR2-dependent activation of NLRP3 inflammasome in lung-infiltrated neutrophils and macrophages. ENDS-primed dendritic cells had reduced capacity for the generation of Th1 and Th17 cell-driven lung inflammation. Accordingly, extensive immune cell-driven lung injury resulted in severe respiratory dysfunction in CCs-exposed mice, while ENDS caused moderate respiratory dysfunction in experimental animals.

CONCLUSIONS

Continuous exposition to either CCs or ENDS induced immune cell-driven lung damage in mice. ENDS triggered immune response, which was less potent than inflammatory response elicited by CCs and, therefore, caused less severe lung injury and inflammation.

IMPLICATIONS

This is the first study that compared the effects of CCs and ENDS on lung-infiltrated immune cells. Although both CCs and ENDS elicited systemic inflammatory response, immune cell-driven lung injury and inflammation were less severe in ENDS-exposed than in CC-exposed animals. Continuous exposition to ENDS-sourced aerosols was less harmful for respiratory function of experimental animals than CC-derived smoke.

Heated tobacco products- well known or well understood? A national cross-sectional study on knowledge, attitudes and usage in Pakistan

BACKGROUND

Heated tobacco products (HTPs) are reshaping the tobacco industry and just recently, a plan was sought to regularize HTPs in Pakistan. Pakistan provides an intriguing case study in this context, as tobacco use is deeply ingrained in public use. To ensure that future evidence-based policy recommendations are grounded in the public's knowledge, attitudes, and usage of HTPs, a nationwide survey must be conducted.

METHODS

A cross-sectional study was conducted using an online-based questionnaire nationwide in Pakistan. The questionnaire was validated and distributed through convenience sampling. The questionnaire assessed participants' knowledge, attitudes, and usage of HTPs. Descriptive statistics was used to describe participants' response and linear regression was performed at a p-value of < 0.05 using SPSS version 26.

RESULTS

In our sample of 1195 respondents (mean age of 33 years, 41.8% males and 58.2% females), 54.7% had previously heard about HTPs and 16.9% reported using HTPs at least once. Additionally, 38.24% were unsure of the legality of HTP use. Those with monthly household incomes of PKR 100,000 to 500,000, were more likely to have higher knowledge scores (OR:1.80[1.07-3.04]). On the other hand, males (OR:0.70 [0.55-0.89]) and respondents from Balochistan (OR:0.40 [0.22-0.71]) were more likely to have lower knowledge scores. The strongest motivators were the enjoyability of HTPs (55.73%) and usage as a cigarette alternative (54.64%), while the strongest deterrents were the negative health effects (82.68%) and potential for addiction (81.01%).

CONCLUSION

Our study underscores the need for awareness campaigns and interventions concerning HTPs, given prevalent preconceived notions and mixed attitudes among respondents. It was found that women and households with higher incomes scored higher on knowledge. Subjective enjoyment and a substitute for cigarettes were important motivators, but the most mentioned deterrents were the possibility of addiction and the detrimental effects on health. These insights form the basis for informed policy making for non-cigarette tobacco products.

Comparison of the Predictors of Smoking Cessation Plans between Adolescent Conventional Cigarette Smokers and E-Cigarette Smokers Using the Transtheoretical Model

Recently, there has been a shift in smoking patterns among adolescents, with a decrease in the prevalence of conventional cigarette smoking and an increase in the use of electronic cigarettes (e-cigarettes). The harmful effects of e-cigarettes are remarkable, highlighting the need for proactive interventions for adolescent users and smoking cessation that consider the characteristics of both conventional cigarette smokers and e-cigarette users. This study aims to investigate the smoking status of adolescent conventional cigarette and e-cigarette smokers and to analyze the predictors of their smoking cessation plans (SCPs) based on the transtheoretical model. Self-rated health, prior smoking cessation education, consciousness-raising, and dramatic relief as types of experiential processes of change, and formation of helping relationships as a type of behavioral process of change significantly differed according to the type of cigarette behavior among adolescents. The predictors of SCP among adolescents were perceived pros of smoking and academic performance among conventional cigarette smokers and behavioral process of change, perceived pros of smoking, and economic status among e-cigarette users. This study identified differences in the characteristics and predictors of SCP. Strategies tailored to each specific adolescent smoking population are further required to promote smoking cessation.

Heated Tobacco Products Have Detrimental Effects on Rotator Cuff Healing, Similar to Conventional Cigarettes

BACKGROUND

Cigarette smoking impairs rotator cuff healing, but no study, to our knowledge, has focused on the association between heated tobacco products and rotator cuff tears.

METHODS

This study retrospectively investigated 1,133 patients who underwent arthroscopic repair of symptomatic rotator cuff tears between March 2011 and April 2021. Patients were grouped on the basis of their smoking patterns as nonsmokers, cigarette smokers, and heated tobacco smokers. Propensity score matching was used to reduce selection bias, and 45 subjects were selected from each group via 1:1:1 matching. Functional scores and active range of motion were compared among the 3 groups preoperatively and at a 2-year follow-up. Postoperative magnetic resonance imaging was performed 6 months after the surgical procedure to assess structural integrity.

RESULTS

Except for sex, similar baseline characteristics were achieved after propensity score matching. There were no differences in the clinical scores or range of motion between the matched groups either preoperatively or at the 2-year follow-up. However, the retear rate for the matched nonsmoker group was significantly lower (8.9%) than those for the matched cigarette smoker group (31.1%) and the heated tobacco smoker group (28.9%) (p = 0.022). Multivariable logistic regression analysis revealed that the retear rates were 3.403 times higher for the cigarette smoker group and 3.397 times higher for the heated tobacco smoker group than that for the nonsmoker group.

CONCLUSIONS

Heated tobacco users, like conventional cigarette smokers, have worse clinical outcomes with respect to rotator cuff healing than nonsmokers. Regardless of the type of cigarette, abstinence from smoking is necessary for patients undergoing rotator cuff repair surgery.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Heated tobacco product (IQOS) induced pulmonary infiltrates

Background

Heated tobacco products (HTPs) have been marketed as safer alternatives to conventional cigarettes, but emerging evidence suggests potential respiratory risks. We present a case of pulmonary complications associated with IQOS, a popular HTP, contributing to the growing understanding of these risks.

Case description

A 40-year-old chronic smoker switched to IQOS, consuming 1.5 packs per day. He presented with incidental chest radiographic abnormalities and peripheral eosinophilia. Computed tomography of chest revealed pulmonary nodules and ground glass opacities. Bronchoscopy indicated mild eosinophilia. After ruling out other causes, a lung biopsy was recommended but declined. Discontinuation of IQOS led to symptom resolution and radiographic improvement. This case adds to a limited literature on HTP-induced lung injury, with a unique presentation and favorable response to cessation.

Conclusions

The case highlights potential pulmonary complications and the first describing an organizing pattern of lung injury associated with IQOS use, emphasizing the importance of recognizing and discontinuing HTPs in patients with respiratory symptoms or radiographic abnormalities. Further research is needed to elucidate the mechanisms underlying the harmful effects of HTPs and inform public health policies. This case underscores the importance of monitoring and educating individuals about the potential risks of HTPs to respiratory health, especially in the context of smokers switching to these products.

Comparison of Publications on Heated Tobacco Products With Conventional Cigarettes and Implied Desirability of the Products According to Tobacco Industry Affiliation: A Systematic Review

INTRODUCTION

Heated tobacco products (HTPs) have been advertised as "reduced-harm" tobacco products compared to conventional cigarettes (CC); however, no direct evidence supporting HTPs being desirable for human health exists. A previous systematic review reported that evidence on HTPs published in 2017 or earlier was primarily drawn from industry-related papers. We aimed to investigate whether tobacco industry-affiliated studies are more likely to conclude that HTPs are more desirable than CC.

METHODS

PubMed and Ichushi-Web were searched up to March 15, 2022, for studies on HTPs published in 2017 or after. We selected studies that assessed any measures of HTPs and CC, including secondary analyses using gray literature in English or Japanese. We excluded review articles except for a meta-analysis that met the aforementioned criteria. Data on the authors' affiliations, grant, conflict of interest, category of research subjects, and interpretation were extracted. Research members in two groups independently assessed the papers; discrepancies were solved by discussion between the groups.

RESULTS

Overall, 134 studies met the criteria. Eighty-seven (64.9%) of them were affiliated with the tobacco industry. Of the 134 studies, 56.3% (49/87) of the industry-affiliated studies versus 19.1% (9/47) of nonindustry-affiliated studies concluded that HTPs were more desirable than CC (p < .01). No study investigated clinically relevant outcomes, such as disease occurrence.

CONCLUSIONS

Publications on HTPs in the biomedical literature from January 2017 to March 2022 were dominated by tobacco industry-affiliated studies. More than half of them concluded that HTPs were more desirable than CC compared to independent studies.

IMPLICATIONS

Tobacco industry advertises HTPs as "reduced-harm" tobacco products compared to CC. HTP users tend to consider HTPs as alternative tobacco products less harmful than CC (ie, products for "harm reduction"). Our results demonstrated that papers written by tobacco industry-affiliated authors concluded that HTPs were more desirable than CC compared to papers by independent authors. However, all their judgments were based on surrogate outcomes. Surrogate outcomes are not necessarily linked to clinically relevant outcomes such as disease occurrence. Further studies on HTPs using clinically relevant outcomes are warranted by independent authors from tobacco industry.

Short sleep duration and smoking initiation in university students: a retrospective cohort study

PURPOSE

The aim of this study was to clarify an association between short sleep duration and smoking initiation.

METHODS

Participants eligible for this retrospective cohort study were university students who were admitted to a single national university in Japan between 2007 and 2015. Baseline sleep duration and smoking status were measured using general questionnaires at health checkups at admission. During a 6-year observation period, smoking initiation was assessed using general questionnaires at annual health checkups. Cox proportional hazards models adjusted for clinically relevant factors were used to assess the association between sleep duration and smoking initiation.

RESULTS

Of 17,493 men, including 540, 5,568, 8,458, 2,507, and 420 men with sleep duration of < 5, 5-6, 6-7, 7-8, and ≥ 8 h, respectively, smoking initiation was observed in 16.1%, 12.5%, 11.2%, 10.0%, and 11.7%, respectively, during a median observation period of 3.0 years. Men with shorter sleep duration were at a higher risk of smoking initiation (adjusted hazard ratio 1.49 [95% confidence interval 1.19-1.85], 1.11 [1.01-1.22], 1.00 [reference], 0.92 [0.80-1.06], and 1.00 [0.75-1.34], respectively). Of 8,880 women, including 267, 3,163, 4,220, and 1,230 women with sleep duration of < 5, 5-6, 6-7, and ≥ 7 h, respectively, smoking initiation was observed in 4.9%, 2.3%, 2.0%, and 2.2%, respectively, during a median observation period of 3.0 years. A similar dose dependent association was ascertained in women (2.50 [1.39-4.49], 1.18 [0.86-1.62], 1.00 [reference], and 1.22 [0.79-1.89], respectively).

CONCLUSION

This study clarified that university students with short sleep duration were vulnerable to smoking initiation.

Critical appraisal of interventional clinical trials assessing heated tobacco products: a systematic review

OBJECTIVE

To critically assess the methodological characteristics and quality of interventional clinical trials investigating the effects of heated tobacco products (HTPs).

DATA SOURCES

Web of Science (Core collection and MEDLINE), Scopus, MedRxiv, ClinicalTrials.gov and ICTRP trial databases and transnational HTP manufacturer online publication libraries were searched for clinical trials on HTPs published between January 2010 and April 2022.

STUDY SELECTION

Interventional clinical trials of any design, in which at least one group of adult participants used a currently marketed HTP, were selected by two reviewers with good or very good agreement.

DATA EXTRACTION

Data relating to trial characteristics and effects of intervention on primary outcomes were extracted using a predesigned form. Risk of bias was assessed using Cochrane's Risk of Bias tool v1.

DATA SYNTHESIS

40 trials were included, 29 of which were tobacco industry affiliated. Methodological characteristics, such as registration, design, setting, comparator interventions, participants, outcomes and analyses, varied between trials, though there were few significant differences between industry-affiliated and independent trials. Of the 40 trials, 33 were judged to be at high risk of bias and 6 at unclear risk of bias. Trial findings were not significantly associated with either affiliation or risk of bias.

CONCLUSIONS

The conduct and reporting of HTP interventional clinical trials were poor in many respects and limited to investigating effects of short-term exposure. These trials fall short of what is needed to determine whether HTPs are beneficial to public health, meaning they may not be a sound basis for tobacco control policy decisions.

Comparative evaluation of ten blood biomarkers of inflammation in regular heated tobacco users and non-smoking healthy males-a pilot study

Heated tobacco products (HTPs) are novel tobacco products that are alternatives to cigarettes. The study aimed to investigate the effect of HTPs on blood biomarkers of inflammation as well as to provide a comparative evaluation between daily heated tobacco users and healthy men who do not use nicotine products. This case-control study was carried out among 92 healthy males in Poland (Lodz-Province) aged 20-56 years: 44 daily heated tobacco users (daily use in the past 90 days) and 48 controls who do not use nicotine products. The history of use of the nicotine-containing products was self-reported and verified using a saliva cotinine test. A 20 ml blood sample was collected and the levels of ten blood biomarkers were analyzed. Among all heated tobacco users (n = 44), only the levels of interleukin 8 (IL-8) were significantly higher when compared to controls: 6.86 vs. 3.95 (p = 0.01). Among exclusive heated tobacco users (n = 33), the levels of IL-8 were also significantly higher when compared to controls: 7.76 vs. 3.95 (p = 0.01). IL-8 level was positively correlated (r = 0.37; p = 0.01) with the daily number of heated tobacco sticks. Out of 10 different biomarkers of inflammation, only IL-8 levels were significantly elevated in heated tobacco use compared to controls.

Nicotine or marijuana vaping exposure during pregnancy and altered immune responses in offspring

Electronic nicotine delivery systems (ENDS) - which include electronic cigarettes or e-cigarettes, or simply e-cigs, and marijuana vaping have become increasingly popular. ENDS devices have been established as one of the tobacco quit methods and promoted to be safer compared to traditional tobacco cigarettes. Emerging evidence demonstrates that e-cigarette and marijuana vape use can be harmful, with potential associations with cancer. Herein, we summarize the level of evidence to date for altered immune response, with a focus on cancer risks in the offspring after maternal use of, or aerosol exposures from, ENDS or marijuana vape during pregnancy. From 27 published articles retrieved from PubMed, we sought to find out identified carcinogens in ENDS aerosols and marijuana vapor, which cross the placental barrier and can increase cancer risk in the offspring. Carcinogens in vaping aerosols include aldehydes, metals, tobacco-specific nitrosamines, tobacco alkaloids, polycyclic aromatic hydrocarbons, and volatile organic compounds. Additionally, there was only one passive vaping exposure case study on a human fetus, which noted that glycerol, aluminum, chromium, nickel, copper, zinc, selenium, and lead crossed from the mother to the offspring's cord blood. The carcinogens (metals) in that study were at lower concentrations compared to the mother's biological matrices. Lastly, we observed that in utero exposures to ENDS-associated chemicals can occur in vital organs such as the lungs, kidneys, brain, bladder, and heart. Any resulting DNA damage increases the risk of tumorigenesis. Future epidemiological studies are needed to examine the effects of passive aerosol exposures from existing and emerging electronic nicotine and marijuana products on developing offspring to cancer.

Prevalence and reasons for use of heated tobacco products among Malaysian adults who smoked: Findings from the 2020 International Tobacco Control Malaysia Survey

INTRODUCTION

There have been rapid expansions in heated tobacco products (HTPs) outside of Japan and the Republic of Korea. In November 2018, HTPs were first introduced in Malaysia and since then, no studies have been conducted on Malaysians' use of HTPs. This study is the first to examine the prevalence of HTP use and reasons for use among Malaysian adults who smoked cigarettes.

METHODS

Data came from the 2020 ITC Malaysia Survey, a web-based survey of a nationally representative sample of adults who smoked (n=1047) aged 18 and older. They were asked on ever heard of, ever used, and currently using HTPs, and their reasons for using HTPs.

RESULTS

Overall, 25.4% (n= 324; 95% CI:22.3%-28.7%) of Malaysians who smoked reported ever used HTPs with 6.7% (n=85; 95% CI:22.3%-28.7%) were using them daily and 8.1% (n=110; 95% CI:6.4% -10.2%) were using HTPs non-daily. Most of them (57.2%) who dual use were of aged 25-39 and 97.3% were males. Among those who smoked daily, almost half (49.3%) were also using HTP daily. Among those who used HTPs daily and non-daily, curiosity (84.2%, 95% CI:78.4%-90.0%), taste (83.2%, 95% CI:77.3%-89.1%), and appealing technology (78.5%, 95% CI:71.3%-85.6%) were the most reported reasons. Among those who used HTPs daily, curiosity was the top reason (87.9%, 95% CI:78.9%-93.4%), while among non-daily, taste good was the top reason (81.9%, 95% CI:71.9%-88.8%).

CONCLUSIONS

The very high use of HTPs among Malaysians who smoked requires continued public health surveillance that can inform the regulation of these novel tobacco products.

Association between heated tobacco product use and airway obstruction: a single-centre observational study, Japan

BACKGROUND

While heated tobacco products (HTPs) may affect pulmonary function, the evidence supporting the utility of screening for HTP use in clinical settings is insufficient. We examined the association between HTP use and airway obstruction after switching from cigarettes.

METHOD

The study subjects were patients aged ≥20 years undergoing surgery from December 2021 to September 2022 who completed spirometry and reported tobacco (cigarette and HTP) use status during the preoperative assessment. Airway obstruction was defined as forced expiratory volume in 1 s to forced vital capacity ratio below the lower limit of normal. Current tobacco use was defined as past-30-day use. Multivariable Poisson regression analysis was performed to examine the associations between HTP use and airway obstruction by adjusting for demographic characteristics, lifetime cigarette smoking (pack-year) and duration of smoking cessation.

RESULTS

Overall (N=2850, 55.4% women, mean age 62.4), 4.6% and 10.7% reported current HTP use and cigarette smoking, respectively. 16.8% had airway obstruction. Airway obstruction was more common among current HTP-only users (adjusted prevalence ratio (APR)=2.32), current cigarette-only smokers (APR=2.57) and current dual users (APR=2.82) than never-tobacco users. Among current tobacco users (N=398), the prevalence of airway obstruction was not significantly different between HTP-only users and cigarette-only smokers. Among former cigarette smokers (>30-day cigarette quitters) (N=1077), current HTP users had 1.42 times the increased prevalence of airway obstruction than never-HTP users after adjusting for cigarette pack-year; a stronger association was observed when the analysis was restricted to ≥5-year cigarette quitters (N=772) (APR=1.96, vs never HTP users).

CONCLUSION

Current HTP use was associated with airway obstruction among patients with cancer who had completely switched from cigarettes even after quitting smoking for a long period. Patients should be routinely screened for HTP use and advised to quit any tobacco.

What Can Current Biomarker Data Tell Us About the Risks of Lung Cancer Posed by Heated Tobacco Products?

INTRODUCTION

Heated tobacco products (HTPs) are marketed as less harmful alternatives to cigarettes, but the lung cancer risk of HTPs is unknown. In the absence of epidemiological data, assessing the risks of HTPs relies on biomarker data from clinical trials. This study examined existing biomarker data to determine what it tells us about the lung cancer risk posed by HTPs.

AIMS AND METHODS

We identified all biomarkers of exposure and potential harm measured in HTP trials and evaluated their appropriateness based on ideal characteristics for measuring lung cancer risk and tobacco use. The effects of HTPs on the most appropriate biomarkers within cigarette smokers switched to HTPs and compared to continued cigarette smoking or cessation were synthesized.

RESULTS

Sixteen out of eighty-two biomarkers (7 exposure and 9 potential harm) measured in HTP trials have been associated with tobacco use and lung cancer, dose-dependently correlated with smoking, modifiable upon cessation, measured within an appropriate timeframe, and had results published. Three of the exposure biomarkers significantly improved in smokers who switched to HTPs and were not significantly different from cessation. The remaining 13 biomarkers did not improve-in some instances worsening upon switching to HTPs-or were inconsistently affected across studies. There were no appropriate data to estimate the lung cancer risk of HTPs in non-smokers.

CONCLUSIONS

The appropriateness of existing biomarker data in assessing lung cancer risk of HTPs, both relative to cigarettes and their absolute risk, is limited. Furthermore, findings on the most appropriate biomarkers were conflicting across studies and largely showed no improvement following a switch to HTPs.

IMPLICATIONS

Biomarker data are fundamental to assessing the reduced risk potential of HTPs. Our evaluation suggests much of the existing biomarker data on HTPs is inappropriate for determining the risk of lung cancer posed by HTPs. In particular, there is a paucity of data on the absolute lung cancer risk of HTPs, which could be obtained from comparisons to smokers who quit and never smokers exposed to or using HTPs. There is an urgent need for further exploration of the lung cancer risks posed by HTPs, via clinical trials and, in the long-term, confirmation of these risks via epidemiological studies. However, careful consideration should be given to biomarker selection and study design to ensure both are appropriate and will provide valuable data.

Liver toxicity in rats after subchronic exposure to HTP aerosol and cigarette smoke

Background

Heated tobacco product (HTP) considered to be a novel tobacco product which was reported safer than traditional cigarettes evidenced by lower potential harmful components released. Liver is an important detoxification organ of the body, the chemical components in aerosols are metabolized in the liver after absorbed, so it is necessary to explore the effect of HTP on the liver.

Materials and Methods

The potential effect of HTP and cigarette smoke (CS) on SD rats was explored according to OECD 413 subchronic inhalation. The rats were randomly divided into Sham (air), different dosage of HTP groups (HTP_10, 23 and 50 μg nicotine/L aerosol) and Cig_23 (23 μg nicotine/L aerosol) group. After exposure, the clinical pathology, inflammation and oxidative stress were measured.

Results

The clinical pathology results showed that both HTP_50 and Cig_23 led to abnormality of ALT for male rats. CS and HTP exposure reduced the expression of IL-1β, IL-6 and TNF-α and mitochondrial medicated oxidative stress. In addition, the ATP production was reduced in Cig_23 group. Although inflammation and oxidative stress were displayed, no apoptosis were observed by TUNEL assay and these existed obvious pathological changes only in HTP_50 group, while in CS group with equivalent nicotine, hepatocytes swelling were observed in liver.

Conclusion

CS exposure induced liver damage through mitochondrial mediated oxidative stress and inflammation, which was also observed in high concentration of HTP exposure group. For the same equivalent nicotine, HTP may show lower toxic effect on liver than CS.

Changes in smoking patterns and characteristics of Koreans using the Korea National Health and Nutrition Examination Survey 2013-2021 data

OBJECTIVES

This study explored factors related to Korean adults' smoking patterns and also the reasons for using new types of tobacco products.

STUDY DESIGN

Cross-sectional survey.

METHODS

Data from the Korea National Health and Nutrition Examination Survey from 2013 to 2021 were used. The prevalence of the use of electronic cigarettes (e-cigarettes) or heated tobacco products (HTPs) alone or in combination with conventional cigarettes (CC) and the reasons for using new tobacco products are presented. Factors associated with using new types of tobacco products alone or in combination with CC compared to exclusive CC users were identified using multinomial logistic regression analysis.

RESULTS

The prevalence of current smoking was 25.54% in 2013 and 23.05% in 2021, with no significant change. The prevalence of CC decreased from 23.39% in 2013 to 15.77% in 2021. The prevalence of new tobacco use in combination with CC did not show a definite trend. The prevalence of exclusive use of new tobacco was <1% until 2018 and has rapidly increased thereafter. Of the HTPs users, 46.68% responded with 'no cigarette smell' as the main reason for HTPs use, followed by 'It seems less harmful than cigarette' (19.19%), and 'It seems to be helpful for quitting smoking' (15.04%). Of the e-cigarette users, 45.19% responded 'It seems to be helpful for quitting smoking' as the main reason for e-cigarette use, followed by 'It is less harmful than cigarettes' (19.98%). Compared to CC users, new tobacco users were younger, had a higher household income or education, and used more nutritional supplements.

CONCLUSION

Regulations for newer tobacco products are more lenient than for traditional cigarettes, leading to misunderstandings, especially among women and young people. To increase awareness of the risks of these products, specific policies such as disclosure of ingredients, ban on online sales, and increase in consumption tax, are needed.

Periodontal Health Status in Adults Exposed to Tobacco Heating System Aerosol and Cigarette Smoke vs. Non-Smokers: A Cross-Sectional Study

Tobacco heating systems (THS) are new products on the market, advertised as a less harmful alternative for smokers, in which tobacco is heated and not burned like in conventional cigarettes. This research explored the effect on periodontal tissues in contact with heating and burning tobacco residual products (smoke and tobacco).

METHODS

The sample included 66 subjects, patients of the Clinic of Dentistry in Rijeka, Croatia, aged 26-56 (median 38), 64% females. Three age- and gender-matched groups were formed (each N = 22): non-smokers, classic cigarettes smokers and THS smokers. Probing depth (PD) and clinical attachment loss (CAL) were primary research parameters.

RESULTS

Three groups differed in average PD and CAL (p ≤ 0.002), with cigarette smokers having the highest and non-smokers the lowest values (p ≤ 0.002). THS consumers generally had lower values of periodontal indices than smokers, but only CAL differed significantly (p = 0.011). Periodontal indices CAL and PD were worse in THS consumers than non-smokers, but they did not reach a level of statistical significance. Cigarette smoking was the only predictor of periodontitis (average CAL ≥ 4 mm) in logistic regression models, with an odds ratio of 4.7 (95% confidence interval 1.2-18.3; p = 0.027).

CONCLUSIONS

Exposure to nicotine-containing aerosol of THS in adults has a less harmful effect on periodontal tissues, measurable through periodontal indices (PD and CAL), compared to burning tobacco of conventional cigarettes. THS, presented as an alternative product to classic cigarettes, also has a detrimental effect on the periodontium.

Evaluation of Cytotoxic and Genotoxic Effects in Buccal Mucosal Cells in Non-Smokers and Users of Traditional Combustible Tobacco Products and Non-Combustible Alternatives

AIMS/OBJECTIVES

The aim of this cross-sectional observational study was to investigate cytogenetic damage to the buccal mucosa in non-smokers and consumers of traditional combustible tobacco products and non-combustible alternatives.

METHODS

A total of 160 participants were divided into four groups according to the type of product used, including non-smokers, users of conventional combustible tobacco (cigarettes), heated tobacco, and electronic, tobacco-free vapor products (e-cigarettes). Buccal mucosa samples were analyzed using the micronucleus cytome assay to assess cytotoxic and genotoxic damage.

RESULTS

E-cigarette users showed significantly higher values for all tested parameters in the micronucleus test compared to non-smokers (p < 0.05). Similarly, users of tobacco heating products showed an increase in all parameters (p < 0.05), with the exception of the number of cells with micronuclei. Conventional cigarette smokers showed a notable increase in the number of binucleated cells and cells with karyorrhexis and karyolysis (p ≤ 0.05). When assessing the differences between users of traditional combustible tobacco products and non-combustible alternatives, these did not appear to be significant, except for e-cigarette users, who had significantly more cells with condensed chromatin (p ≤ 0.001), while users of tobacco heating products had more pyknotic cells (p ≤ 0.001).

CONCLUSION

The results of this study underscore the heightened occurrence of cytotoxic and genotoxic damage in users of both conventional combustible tobacco products and non-combustible alternatives compared to non-smokers, emphasizing the detrimental impact of these products on the oral mucosa.

Exposure to IQOS ads and reduced exposure claims, and association with perceived risk from COVID-19 on IQOS purchase and use intentions: results from a web-based survey

Introduction

IQOS was authorized to be marketed as a reduced exposure product by the Food and Drug Administration in October 2020 during the global COVID-19 pandemic. Those who smoke may be more sensitive to reduced exposure marketing claims and may have an increased inclination toward IQOS use. We evaluated the likelihood of trying and purchasing IQOS as a function of exposure to ads, product appeal, and COVID-19 risk perceptions using the original IQOS ads with reduced exposure marketing.

Method

An online cross-sectional survey recruited 604 US adults (18-45 years), both who smoke and do not smoke. Participants saw one of the six randomly assigned IQOS ads with or without reduced exposure claims, and they answered questions about product appeal and likelihood to try and purchase IQOS. Generalized linear models were used to examine associations.

Results

A per unit increase in product appeal was associated with a greater likelihood of purchasing (B = 0.17, 95% CI: 0.15-0.18) and trying IQOS (B = 0.16, 95% CI = 0.14-0.18). Current smokers and former e-cigarette users reported greater intentions to try IQOS than never-smokers and never e-cigarette users, respectively. Likelihood to purchase IQOS was associated with greater confidence in not contracting COVID-19 (B = 0.11, 95% CI: 0.01-0.21). No significant differences were observed between different ad conditions. Current (B = -0.34, 95% CI = -0.50-(-0.19)) and former (B = -0.92, 95% CI = -0.15-(-0.68)) cigarette smokers who were someday e-cigarette users reported less intentions to purchase IQOS than never e-cigarette users. However, never smokers who were someday (B = 0.58, 95% CI = 0.27-0.89; B = 0.68, 95% CI = 0.39-0.98) and former e-cigarette (B = 0.38, 95% CI = 0.15-0.61) users reported greater intentions to purchase and try IQOS, respectively.

Discussion

IQOS may have a higher product appeal, especially for those who currently smoke and those who have lower risk perceptions from COVID-19. Among never smokers, those who currently use or have used e-cigarettes in the past may be more receptive to IQOS marketing. The data are informative for potential trends in the use of IQOS in the future and may have implications for marketing regulations of heated tobacco products (HTPs).

Exploring the association between the proximity to and density around schools of retailers selling IQOS products and youth use of heated tobacco products: evidence from the 2020-2021 COMPASS study

INTRODUCTION

Heated tobacco products (HTPs) are novel tobacco products that may appeal to youth. This study explored whether HTP retailer proximity and density to secondary schools were associated with youth use of HTPs in four Canadian provinces.

METHODS

An online search between November 2020 and March 2021 identified retailers selling IQOS devices and HEETS (tobacco sticks used in IQOS) within 500 m, 1000 m and 1500 m radius circular buffer zones around high schools (N = 120) participating in the COMPASS study in 2020-2021. Retailer proximity/density data were linked to crosssectional student-level data (N = 40 636 students), and multilevel regression models examined the association between HTP retailer proximity and density and current HTP use, controlling for relevant covariates.

RESULTS

While only 10.0% of schools had at least one retailer selling IQOS devices within 1000 m of the school, 65.0% of schools had at least one retailer selling HEETS. The school a student attended accounted for 23.7% of the variability in the likelihood of currently using an HTP. However, HTP retailer proximity to and density around schools were not significantly associated with the likelihood of students currently using HTPs.

CONCLUSION

While the school a student attended accounted for a significant amount of variability in HTP use, these findings suggest that students may be obtaining HTPs through other, non-retail sources. Continued monitoring is warranted as HTP use among youth may change.

Impact of Electronic Cigarettes, Heated Tobacco Products and Conventional Cigarettes on the Generation of Oxidative Stress and Genetic and Epigenetic Lesions in Human Bronchial Epithelial BEAS-2B Cells

Electronic cigarettes (e-cig) and heated tobacco products (HTP) are often used as smoking cessation aids, while the harm reduction effects of these alternatives to cigarettes are still the subject of controversial debate, in particular regarding their carcinogenic potential. The objective of this study is to compare the effects of e-cig, HTP and conventional cigarette emissions on the generation of oxidative stress and genetic and epigenetic lesions in human bronchial epithelial BEAS-2B cells. Our results show that HTP were less cytotoxic than conventional cigarettes while e-cig were not substantially cytotoxic in BEAS-2B cells. E-cig had no significant effect on the Nrf2 pathway, whereas HTP and cigarettes increased the binding activity of Nrf2 to antioxidant response elements and the expression of its downstream targets HMOX1 and NQO1. Concordantly, only HTP and cigarettes induced oxidative DNA damage and significantly increased DNA strand breaks and chromosomal aberrations. Neither histone modulations nor global DNA methylation changes were found after acute exposure, regardless of the type of emissions. In conclusion, this study reveals that HTP, unlike e-cig, elicit a biological response very similar to that of cigarettes, but only after a more intensive exposure: both tobacco products induce cytotoxicity, Nrf2-dependent oxidative stress and genetic lesions in human epithelial pulmonary cells. Therefore, the health risk of HTP should not be underestimated and animal studies are required in order to determine the tumorigenic potential of these emerging products.

Salivary microRNAs as innovative biomarkers for early diagnosis of oral diseases: a comparison of conventional cigarette smokers and tobacco heating system 2.2 users

BACKGROUND

MicroRNAs (miRNAs) are considered valid prognostic and diagnostic biomarkers. The different miRNA expression profiles in cancer cells compared to normal cells make them potential biomarkers used for the early diagnosis of oral diseases. Following exposure to cigarette smoking, miRNA altered profile expression is associated with resistance mechanisms against anticancer therapies. Cellular models showed a reduced human gingival epithelium alteration after exposure to THS2.2 and a lower pathogenicity than 3R4F CS. The aim of the study was to compare the expression of saliva miRNA profile of THS2.2 and 3R4F CS users compared to patients not exposed to the risk factor and to identify and study the modulation of miRNAs associated with the development of oral diseases. In particular, we will focus on the analysis of a group of miRNAs know to be involved in the development of smoking-related diseases.

METHODS

The study will be performed in 18 months and dentists and biochemists will be involved in the different phases. To perform the study, healthy volunteers, including smokers of THS2.2 or 3R4F CS, will be enrolled.

RESULTS

The samples will be collected from 3 experimental groups, each consisting of 30 subjects: group 1 (no smoking subjects), group 2 (subjects exposed to THS2.2), group 3 (subjects exposed to 3R4F CS). The collection of the saliva sample will be conducted in a standardized way. Following the collection, saliva will be processed.

CONCLUSIONS

Previous studies have suggested that miRNAs are prognostic biomarkers for various smoking-related diseases. Based on the post-transcriptional regulation of some mRNAs connected to different oral pathologies, we expect a specific miRNA-mRNA interaction, which could be a starting point for the development of new possible diagnostic, therapeutic and prognostic approaches.

Effects of heated tobacco product aerosol extracts on DNA methylation and gene transcription in lung epithelial cells

AIMS

Smoking causes DNA methylation (DNAm) alterations that lead to lung cancer development. Although the use of heated tobacco products (HTPs) has recently increased, their impact on health remains unclear. This study aimed to evaluate the effects of HTPs on DNAm and gene transcription in human lung epithelial cells in vitro.

MAIN METHODS

Human lung adenocarcinoma (A549) cells with type II alveolar epithelial characteristics were treated with aerosol extracts of two HTPs or a smoke extract of combustible reference cigarette (RC). Global 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) levels were quantified using dot blot analysis. Furthermore, reduced representation of bisulfite sequencing, DNA microarray, and quantitative PCR analyses were performed to determine CpG methylation and gene transcription changes induced by HTP and RC.

KEY FINDINGS

Global 5-mC and 5-hmC levels were decreased by the RC extract but not the HTP extracts. However, an HTP extract altered the CpG methylation pattern, and Gene Ontology enrichment analysis of the differentially methylated regions of the RC and HTP groups showed a similar pattern. The HTP extract affected gene expression, albeit to a lesser extent than the RC extract. In particular, the HTP extract markedly affected the mRNA expression and promoter methylation of cytochrome P450 family 1 subfamily A member 1 (CYP1A1), which is associated with carcinogenic risk.

SIGNIFICANCE

The study results suggest that HTPs as well as conventional combustible cigarettes can alter CpG methylation and gene transcription in lung epithelial cells.

Impact of Heated Tobacco Products, E-Cigarettes, and Combustible Cigarettes on Small Airways and Arterial Stiffness

Smoking cessation is difficult but maintaining smoke-free without nicotine replacement therapy is even harder. During the last few years, several different alternative products, including heated tobacco products (HTP), have been introduced to the market. In this study, we investigated the acute effects of IQOSTM and gloTM (two HTP) consumption on small airway function and arterial stiffness in a head-to-head design, comparing them to combustible cigarettes, nicotine-free e-cigarettes and a sham smoking group. Seventeen healthy occasional smokers were included in a single-center, five-arm, crossover study. The parameters of small airway function and hemodynamics were collected at several time points before and after consumption using Mobil-O-Graph™ (I.E.M., Stolberg, Germany) and TremoFlo® c-100 (THORASYS Thoracic Medical Systems Inc., Montreal, QC, Canada). Small airway obstruction and resistance were both significantly increased after the consumption of cigarettes and substitute products. All products containing nicotine led to similar significant increases in blood pressure and arterial stiffness. Hemodynamic parameters were also increased after the consumption of e-cigarettes without nicotine, but compared to nicotine-containing products, the increase was shorter and weaker. We conclude that, although it has yet to be determined why, HTP have acute harmful effects on small airway function, possibly even exceeding the effects of combustible cigarettes. Like other nicotine-containing products, HTP leads to a nicotine-related acute increase in arterial stiffness and cardiovascular stress, similar to combustible cigarettes, which associates these products with an increased cardiovascular risk.

The relationship between heated cigarette smoking and blood white blood cell count: a population-based cross-sectional study

OBJECTIVES

Conventional cigarette smoking increases inflammation and white blood cell (WBC) counts. However, there have been limited studies on the relationship between heated cigarette smoking and WBC counts. This study aimed to examine this relationship using nationally representative population-based health data.

STUDY DESIGN

This was a population-based cross-sectional study.

METHODS

The Korea National Health and Nutrition Examination Survey database was used to analyze this relationship. Data related to sex, age, body mass index (BMI), WBC count, and smoking history were obtained from the database. The smoking-related questionnaires included smoking status, smoking type (heated or conventional cigarettes), and smoking amount. The summary statistics of the WBC counts were calculated according to sex, smoking status, and smoking type. In addition, the exposure-response relationship between the smoking amount and WBC count was examined by smoking type, controlling for sex, age, and BMI.

RESULTS

In total, 9747 WBC measurements were used in the analyses. WBC count increased in conventional cigarette smokers, while there was no significant difference in WBC count between heated cigarette smokers and non-smokers. The WBC count showed a positive dose-response relationship with the smoking amount in both conventional and heated cigarette smokers.

CONCLUSIONS

The results confirm that conventional cigarette smoking increases WBC counts. Furthermore, the results suggest that heated cigarette smoking does not lead to a significant increase in WBC counts, although it indicates a potential dose-response relationship with WBC count. Further research with larger sample sizes is needed to confirm whether these results reflect true associations.

How Media Stories in Low- and Middle-Income Countries Discussed the U.S. Food and Drug Administration's Modified Risk Tobacco Product Order for IQOS

INTRODUCTION

In 2020, the U.S. Food and Drug Administration authorized the marketing of IQOS as a modified risk tobacco product (MRTP) with reduced exposure information (reduces exposure to harmful chemicals compared to cigarettes) but prohibited Philip Morris International from making reduced risk claims (reduces risk of disease compared to cigarettes). We aimed to assess how news media in low- and middle-income countries (LMICs) discussed this authorization and whether articles discussed IQOS as a reduced exposure versus reduced risk product.

AIMS AND METHODS

News articles published between July 7, 2020 and January 7, 2021 were obtained by searching Tobacco Watcher (www.tobaccowatcher.org), a surveillance platform for tobacco-related news. Articles were eligible if they were published in an LMIC and mentioned the IQOS MRTP order. Non-English language articles were professionally translated. Articles were double coded to identify country of origin, reduced risk and reduced exposure language, discussions of potential impacts of the authorization on regulations in LMICs, and quotes from tobacco industry and public health stakeholders.

RESULTS

We identified 50 eligible articles published in 20 LMICs. Twenty-six (52%) and 40 (80%) included reduced risk and reduced exposure language, respectively. Twenty-two (44%) discussed potential impacts of the MRTP order on regulations in LMICs. Thirty (60%) included quotes from tobacco industry representatives, 6 (12%) included quotes from public health or medical professionals, and 2 (4%) included both.

CONCLUSIONS

News articles in LMICs frequently misreported the MRTP order by using reduced risk language. The authorization is potentially being used to shape perspectives on tobacco regulations in LMICs. Tobacco control experts need to more frequently share their perspectives with the news media.

IMPLICATIONS

News articles from LMICs frequently misrepresented the IQOS MRTP order by using reduced risk language (reduces harm compared to cigarettes) rather than only using reduced exposure language (reduces exposure to harmful chemicals compared to cigarettes). Many articles referred to IQOS as a "better alternative" to cigarettes without specifically referencing reduced risk. Few articles included perspectives from public health or medical professionals, while most included tobacco industry quotes, suggesting that tobacco control experts need to more frequently engage with the news media. These findings also highlight how the U.S. FDA's actions can potentially shape perspectives on tobacco product regulations in LMICs.

Association between smoking and obstructive sleep apnea based on the STOP-Bang index

Smoking is a risk factor for respiratory diseases, and it worsens sleep quality due to nicotine stimulation and sudden nicotine withdrawal during sleep. This can increase the severity of OSA through alterations upper airway inflammation and neuromuscular function, arousal mechanisms, and sleep architecture. Therefore, it may lead to sleep-disrupted breathing, particularly obstructive sleep apnea (OSA). Herein, this study aims to research the association between smoking and OSA through the STOP-Bang index. In this study, total sample of 3442 participants (1465 men and 1977 women) were analyzed. We used data from the Korea National Health and Nutrition Examination Survey in 2020 by classifying adults into current, ex-, and non-smokers. A multiple logistic regression analysis was used to investigate the association between smoking and OSA. Furthermore, multinomial regression analysis was used to investigate the effect of smoking cessation. For males, compared to the non-smokers, the odds ratios (OR) for the OSA were significantly higher in the ex-smokers (OR: 1.53, 95% confidence interval(CI) 1.01-2.32) and current smokers (OR: 1.79, 95% CI 1.10-2.89). In females, higher ORs were observed for OSA risk, similar to the non-smokers, smoking cessation, and pack-years. Among men, OSA was significantly associated with a moderate risk for ex-smokers (OR: 1.61, 95% CI 1.05-2.48) and a severe risk for current smokers (OR: 1.88, 95% CI 1.07-3.29). This study observed that smoking might contribute to OSA risk among adults. Smoking cessation can help to manage sleep quality properly.

Study on the effect of enzymatic treatment of tobacco on HnB cigarettes and microbial succession during fermentation

Starch and cellulose are the fundamental components of tobacco, while their excessive content will affect the quality of tobacco. Enzymatic treatment with different enzymes is a promising method to modulate the chemical composition and improve the sensory quality of tobacco leaves. In this study, enzymatic treatments, such as amylase, cellulase, and their mixed enzymes, were used to improve tobacco quality, which could alter the content of total sugar, reducing sugar, starch, and cellulose in tobacco leaves. The amylase treatment changed surface structure of tobacco leaves, increased the content of neophytadiene in tobacco by 16.48%, and improved the total smoking score of heat-not-burn (HnB) cigarette products by 5.0 points compared with the control. The Bacillus, Rubrobacter, Brevundimonas, Methylobacterium, Stenotrophomonas, Acinetobacter, Pseudosagedia-chlorotica, and Sclerophora-peronella were found to be significant biomarkers in the fermentation process by LEfSe analysis. The Basidiomycota and Agaricomycetes were significantly correlated with aroma and flavor, taste, and total score of HnB. The results showed that microbial community succession occurred due to amylase treatment, which promoted the formation of aroma compounds, and regulated the chemical composition of tobacco, and improved tobacco quality during tobacco fermentation. This study provides a method for enzymatic treatment to upgrade the quality of tobacco raw materials, thereby improving the quality of HnB cigarettes, and the potential mechanism is also revealed by chemical composition and microbial community analysis. KEY POINTS: Enzymatic treatment can change the chemical composition of tobacco leaves. The microbial community was significantly affected by enzymatic treatment. The quality of HnB cigarettes was significantly improved by amylase treatment.

The associations between cigarette smoking behavior and the use of heated tobacco products among Arab cigarette smokers: Findings from Saudi Arabia, Egypt, Kuwait, and Yemen

As the availability of tobacco forms has evolved, emerging products known as heated tobacco products (HTPs) are increasingly being consumed worldwide and are claimed to be less harmful than tobacco cigarette smoking. To date, it is unknown whether Arab cigarette smokers are using or susceptible to HTPs. Therefore, this study aimed to assess the association between cigarette smoking behavior and the use of and susceptibility to HTPs in the Eastern Mediterranean region. Arab cigarette smokers (n = 628) from Saudi Arabia, Egypt, Kuwait, and Yemen were recruited using a convenience sampling technique. A cross-sectional survey comprised questions related to sociodemographic characteristics, cigarette smoking behavior characteristics (quitting attempts and desire to quit cigarette smoking, nicotine dependence, and consideration of switching to nicotine products with reduced health risks), and awareness of, use of, and susceptibility to use of HTPs. Descriptive and logistic regression models were used for analysis. The participants indicated a high frequency of past quitting attempts and a desire to quit smoking cigarettes. They were also considering switching to a nicotine product with reduced health risks. However, their awareness of HTPs was relatively low (24.2%), and the proportion of participants who had ever used HTPs or were currently using them was quite low as well (10.7% and 5.0%, respectively). A history of quit attempts was associated with more likely lifetime use of HTPs (adjusted odds ratio [AOR] = 2.63, 95% confidence interval [CI] [1.21-5.71]). Nicotine-dependent cigarette smokers were more likely to be susceptible to HTP use (AOR = 1.12, 95% CI [1.01-1.24]). Moreover, those who would consider switching to a product that provided nicotine and could reduce health risks by 99% were more likely to be susceptible to using HTPs (AOR = 2.17, 95% CI [1.05-4.51]). Awareness of HTPs is relatively low among Arab cigarette smokers. Attempts to quit cigarette smoking, nicotine dependence, and the consideration of switching to a product that delivers nicotine with reduced health risks were significantly associated with using HTPs. The findings of this study provide potential for evidence-based treatment for smokers and will help prevent the use of tobacco industry tactics in marketing HTPs.

Comparison of the Smoking Cessation of Heated Tobacco Product Users and Conventional Cigarette Smokers in Korea

BACKGROUND

Since the introduction of heated tobacco products (HTPs) in Korea in 2017, their annual sales have increased. Several studies have investigated the perceptions of HTPs and smoking cessation behaviors. For the first time, In 2019, questions focused on HTP use were introduced in the Korea National Health and Nutrition Examination Survey (KNHNES). This study aimed to compare smoking cessation behaviors between HTP users and conventional cigarette smokers using KNHANES data.

METHODS

Data of 947 current adult smokers from the 8th KNHNES (2019) were analyzed. Current smokers were divided into conventional cigarette (CC)-only, HTP-only, and dual-use groups. The general characteristics of the three groups were investigated. Differences in current intention to quit smoking and past attempts to quit smoking among the three groups were analyzed using multivariate logistic regression analysis by IBM SPSS ver. 25.0.

RESULTS

HTP-only users demonstrated fewer future smoking cessation plans (adjusted odds ratio [AOR], 0.398; 95% confidence interval [CI], 0.195-0.813; P=0.012) and fewer smoking cessation attempts in the past year (AOR, 0.533; 95% CI, 0.298-0.954; P=0.034) than CC-only smokers. However, there was no significant difference between dual-use (CC+HTP) and CC-only smokers.

CONCLUSION

While dual-use and CC-only smokers showed similar smoking cessation behaviors, HTP-only users had fewer previous attempts to quit smoking and were less likely to be currently ready to quit smoking. These findings can be explained by a decrease in the need to quit smoking due to the convenience of HTP and the perception that HTPs are less harmful than CC.

Diet as a Source of Acrolein: Molecular Basis of Aldehyde Biological Activity in Diabetes and Digestive System Diseases

Acrolein, a highly reactive α,β-unsaturated aldehyde, is a compound involved in the pathogenesis of many diseases, including neurodegenerative diseases, cardiovascular and respiratory diseases, diabetes mellitus, and the development of cancers of various origins. In addition to environmental pollution (e.g., from car exhaust fumes) and tobacco smoke, a serious source of acrolein is our daily diet and improper thermal processing of animal and vegetable fats, carbohydrates, and amino acids. Dietary intake is one of the main routes of human exposure to acrolein, which is a major public health concern. This review focuses on the molecular mechanisms of acrolein activity in the context of its involvement in the pathogenesis of diseases related to the digestive system, including diabetes, alcoholic liver disease, and intestinal cancer.

Heated Tobacco Products and Chronic Obstructive Pulmonary Disease: A Narrative Review of Peer-Reviewed Publications

An estimated 65 million people worldwide have moderate or severe chronic obstructive pulmonary disease (COPD), an umbrella term used to describe a group of progressive lung diseases that obstruct airflow such as emphysema and chronic bronchitis. Smoking contributes to an estimated 90% of COPD cases, as the harmful chemicals produced during tobacco combustion damage the lungs and airways. Although smoking cessation is the only intervention shown to improve COPD prognosis in smokers, many patients who try to quit continue to smoke. The continued use of conventional cigarettes exacerbates COPD symptoms, and globally more than 3 million people die from the disease every year. The last two decades have seen the introduction of combustion-free nicotine delivery alternatives that produce significantly lower levels of the harmful components in cigarette smoke, and researchers have begun to assess the impact of switching from cigarettes to these products. Several studies have examined how patients with COPD use e-cigarettes as assistance for quitting, but few have examined how heated tobacco products (HTP) may reduce risk. This narrative review summarises results from pre-clinical, clinical, and real-world evidence studies showing possible harm reduction benefits for patients with COPD who switch to HTPs rather than continuing to smoke cigarettes. Epidemiological studies, real-world data analyses, and randomised clinical trials must be conducted to determine whether switching from cigarettes to HTPs can improve health outcomes in patients with COPD who would otherwise continue to smoke combustible cigarettes.

Human vasculature-on-a-chip with macrophage-mediated endothelial activation: The biological effect of aerosol from heated tobacco products on monocyte adhesion

Heated tobacco products (HTPs) are expected to have the potential to reduce risks of smoking-associated cardiovascular disease (CVD). However, mechanism-based investigations of the effect of HTPs on atherosclerosis remain insufficient and further studies under human-relevant situations are desired for deeper understanding of the reduced risk potential of HTPs. In this study, we first developed an in vitro model of monocyte adhesion by considering macrophage-derived proinflammatory cytokine-mediated endothelial activation using an organ-on-a-chip (OoC), which provided great opportunities to mimic major aspects of human physiology. Then biological activities of aerosol from three different types of HTPs in terms of monocyte adhesion were compared with that of cigarette smoke (CS). Our model showed that the effective concentration ranges of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were close to the actual condition in CVD pathogenesis. The model also showed that monocyte adhesion was less induced by each HTP aerosol than CS, which may be caused by less proinflammatory cytokine secretion. In summary, our vasculature-on-a-chip model assessed the difference in biological effects between cigarettes and HTPs, and suggested a reduced risk potential of HTPs for atherosclerosis.

Characterizing Heated Tobacco Products Marketing on Instagram: Observational Study

BACKGROUND

Heated tobacco products (HTPs), including I Quit Ordinary Smoking (IQOS), are new tobacco products that use an electronic device to heat compressed tobacco leaves to generate an aerosol for consumers to inhale. Marketing of HTPs is prevalent on Instagram, a popular social media platform.

OBJECTIVE

This study aims to characterize posts related to HTPs on Instagram and their associations with user engagement.

METHODS

Through the Instagram application programming interface, 979 Instagram posts were collected using keywords related to HTPs, such as "IQOS" and "heat-not-burn." Among them, 596 posts were related to IQOS and other HTP marketing. The codebook was developed from a randomly selected 200 posts on the post content by hand coding, which was applied to the remaining 396 Instagram posts. Summary statistics were calculated, and statistical hypothesis testing was conducted to understand the popularity of Instagram posts on HTPs. Negative binomial regression models were applied to identify Instagram post characteristics associated with user engagement (eg, count).

RESULTS

Among Instagram posts related to HTP marketing (N=596), "product display" was dominant (n=550, 92.28%), followed by "brand promotion" (n=41, 6.88%), and "others" (n=5, 0.84%). Among posts within "product display," "device only" was the most popular (n=338, 61.45%), followed by "heatstick only" (n=80, 14.55%), "accessory" (n=66, 12%), "device and heatstick" (n=56, 10.18%), and "capsule" (n=10, 1.82%). A univariate negative binomial regression model with pairwise comparisons across "product display" types showed that the number of likes for posts with HTP heatsticks was significantly lower compared to posts with HTP devices, accessories, and device-heatstick sets. Multivariate negative binomial regression models showed that HTP-related Instagram posts with a model or lifestyle elements (;=.60, 95% CI 0.36-0.84) or without obvious product advertising information (=.69, 95% CI 0.49-0.89) received more likes.

CONCLUSIONS

It is shown that posts with product displays were dominant among HTP-related posts on Instagram. Posts with model or lifestyle elements are associated with high user engagement, which might be one of the web-based marketing strategies of HTPs.

Reasons for Initiation and Regular Use of Heated Tobacco Products among Current and Former Smokers in South Korea: Findings from the 2020 ITC Korea Survey

South Korea is the world's second-largest heated tobacco product (HTP) market after Japan. HTP sales in South Korea have increased rapidly since May 2017, accounting for 10.6% of the total tobacco market in 2020. Despite this, little is known as to why HTP consumers who were current and former smokers started using HTPs and used them regularly. We analyzed cross-sectional data for 1815 adults (aged 19+) who participated in the 2020 International Tobacco Control (ITC) Korea Survey, of whom 1650 were HTP-cigarette consumers (those who reported smoking cigarettes and using HTPs ≥ weekly) and 165 were exclusive HTP consumers (using HTPs ≥ weekly) who were former or occasional smokers (smoking cigarette < weekly). Respondents were asked to report the reason(s) they used HTPs, with 25 possible reasons for HTP-cigarette consumers and 22 for exclusive HTP consumers. The most common reasons for initiating HTP use among all HTP consumers were out of curiosity (58.9%), family and friends use HTPs (45.5%), and they like the HTP technology (35.9%). The most common reasons for regularly using HTPs among all HTP consumers were that they were less smelly than cigarettes (71.3%), HTPs are less harmful to own health than cigarettes (48.6%), and stress reduction (47.4%). Overall, 35.4% of HTP-cigarette consumers reported using HTPs to quit smoking, 14.7% to reduce smoking but not to quit, and 49.7% for other reasons besides quitting or reducing smoking. In conclusion, several common reasons for initiating and regularly using HTPs were endorsed by all HTP consumers who were smoking, had quit smoking completely, or occasionally smoked. Notably, only about one-third of HTP-cigarette consumers said they were using HTPs to quit smoking, suggesting that most had no intention of using HTPs as an aid to quit smoking in South Korea.

The Tobacco Smoke Component, Acrolein, as a Major Culprit in Lung Diseases and Respiratory Cancers: Molecular Mechanisms of Acrolein Cytotoxic Activity

Acrolein, a highly reactive unsaturated aldehyde, is a ubiquitous environmental pollutant that seriously threatens human health and life. Due to its high reactivity, cytotoxicity and genotoxicity, acrolein is involved in the development of several diseases, including multiple sclerosis, neurodegenerative diseases such as Alzheimer’s disease, cardiovascular and respiratory diseases, diabetes mellitus and even the development of cancer. Traditional tobacco smokers and e-cigarette users are particularly exposed to the harmful effects of acrolein. High concentrations of acrolein have been found in both mainstream and side-stream tobacco smoke. Acrolein is considered one of cigarette smoke’s most toxic and harmful components. Chronic exposure to acrolein through cigarette smoke has been linked to the development of asthma, acute lung injury, chronic obstructive pulmonary disease (COPD) and even respiratory cancers. This review addresses the current state of knowledge on the pathological molecular mechanisms of acrolein in the induction, course and development of lung diseases and cancers in smokers.

IQOS Use and Interest by Sociodemographic and Tobacco Behavior Characteristics among Adults in the US and Israel

Heated tobacco products (HTPs) have expanded globally. IQOS, a global HTP leader, was launched in Israel in 2016 and the US in 2019. To inform tobacco control efforts, it is critical to understand who is likely to use HTPs in different countries with distinct regulatory and marketing contexts. Thus, we conducted a cross-sectional survey among adult (ages 18-45) online panelists in the US (n = 1128) and Israel (n = 1094), oversampling tobacco users, in the fall of 2021, and used multivariable regression to identify correlates of (1) ever using IQOS; (2) past-month vs. former among ever users; and (3) interest in trying IQOS among never users. Among US adults, correlates of ever use included being Asian (aOR = 3.30) or Hispanic (aOR = 2.83) vs. White, and past-month use of cigarettes (aOR = 3.32), e-cigarettes (aOR = 2.67), and other tobacco (aOR = 3.34); in Israel, correlates included being younger (aOR = 0.97), male (aOR = 1.64), and cigarette (aOR = 4.01), e-cigarette (aOR = 1.92) and other tobacco use (aOR = 1.63). Among never users, correlates of greater interest included cigarette and e-cigarette use in the US (β = 0.57, β = 0.90) and Israel (β = 0.88, β = 0.92). IQOS use prevalence was low (US: 3.0%; Israel: 16.2%) but represented in vulnerable subpopulations (younger adults, racial/ethnic minorities).

Perceived Health and Capacity to Cope With Stress in Recent Ex-smokers: Impact of Vaping Versus Quitting All Nicotine

INTRODUCTION

Little is known about the continued use of nicotine following smoking cessation on perceived well-being in comparison to complete cessation of nicotine use.

AIMS AND METHODS

To explore aspects of perceived well-being and coping among recent ex-smokers as a function of vaping status. Ever-daily smokers in the International Tobacco Control 4 country smoking and vaping surveys in 2016 (w1 N = 883) and 2018 (w2 N = 1088). Cross-sectional associations and longitudinal samples for those who quit between waves and those who quit at w1 and maintained abstinence to w2. Main outcome measures were: Past 30 days of depression symptoms, perceived stress, stress management since quitting, and change in perceived day-to-day health.

RESULTS

In the cross-sectional analyses vapers were more likely to report both improved stress management (aOR = 1.71, 95% CI 1.23-2.36) and perceived day-to-day health (aOR = 1.65, 95% CI 1.26-2.16) than nicotine abstainers. In the longitudinal analyses, smokers who switched to vaping between waves (n = 372) were more likely to report depression symptoms at w2 (aOR = 2.00, 95% CI 1.09-3.65) but reported improved perceived health (aOR = 1.92, 95% CI 1.16-3.20). For the past daily smokers who remained quit between waves (n = 382), vapers were more likely to report improved stress management relative to abstainers (RRR = 5.05. 95% CI 1.19-21.40). There were no other significant differences between vapers and nicotine abstainers.

CONCLUSIONS

There is little evidence to support the view that perceptions of well-being deteriorate in vapers compared to complete nicotine abstainers in the immediate years after smoking cessation.

IMPLICATIONS

This study could find no conclusive evidence that the continued use of nicotine via e-cigarettes was detrimental to health compared to completely stopping nicotine intake altogether. Our results would suggest that continuing to use nicotine may even result in some benefits in the short term such as improved stress management, however further longitudinal studies are required to examine if these effects are restricted to the early post-quitting phase and whether other positive or negative effects on psychosocial health emerge in the future.

Heated Tobacco Products: Awareness, Beliefs, Use and Susceptibility among US Adult Current Tobacco Users, 2021

Limited data exist on the awareness, beliefs, and use of heated tobacco products (HTPs). Data from 1583 U.S. adult (age ≥ 21 years) current tobacco users were collected in 2021. Participants self-reported HTP awareness, beliefs, use, and susceptibility, as well as current tobacco product use and sociodemographics. We used weighted logistic and multinomial regression models to explore their associations. Overall, 23.6% were aware of, 8.9% had ever used, and 3.0% currently used HTPs. Younger individuals (vs. 61+ years), those with annual income $50,000+ (vs. <$50,000), and those currently using electronic vaping products (vs. non-users) were more likely to be aware of, to have ever used, and to currently be using HTPs (p < 0.05). Black individuals (vs. White) were more likely to report ever and current HTP use (p < 0.05). Current cigarette smoking was not associated with HTP awareness and use (p > 0.05). Holding favorable HTP beliefs was associated with susceptibility to and more advanced HTP use statuses (p < 0.05). Sociodemographics associated with HTP use may reflect HTP marketing strategies. The lack of association with cigarette smoking suggests HTPs may be unlikely cigarette substitutes. Addressing favorable HTP-related beliefs may prevent dual use.

Current Evidence on Tobacco Harm Reduction in Pneumology: Interviews with Two Key Opinion Leaders

The negative impact of smoking on the lung is well documented. Cigarette smoke is the cause of 90% of cases of chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. COPD is a progressive and debilitating condition with morbidity and mortality rates similar to myocardial infarction (MI) and stroke. Despite the widely recognised risks, millions of people continue to smoke, in some cases even after receiving a diagnosis of COPD and despite knowing that the habit will accelerate disease progression. While there is no doubt that smoking cessation is the most important health intervention for all cigarette smokers, it can be challenging. Nicotine addiction, social norms and culture, and the length of time it can take smokers to feel the adverse consequences of the habit all contribute to the high cessation failure rate. However, increasing clinical and epidemiological evidence indicates that for those who are unwilling or cannot stop smoking, harm reduction strategies can help reduce exposure to the harmful chemicals and carcinogens released during tobacco combustion. Electronic devices heat processed tobacco without combusting it to deliver an aerosol containing fewer toxic products or harmful and potentially harmful constituents (HPHC) than cigarette smoke. Clinical evidence to support their use is growing. In Japan, for example, a decrease in hospitalisations due to COPD exacerbation after the introduction of such heat-not-burn (HNB), or tobacco heating systems (THS), has been reported. In this article, Wolfgang Popp, Döbling Doctor’s Center, Privatklinik Döbling, Vienna, Austria, and Klara Szondy, Semmelweis University, Budapest, Hungary, discuss the impact of cigarette smoke on the lung, and how to support smoking cessation in those willing and able to quit smoking. They also explain when strategies that reduce the harmful effects of smoking may be useful, and outline the latest evidence supporting the use of HNB systems.

Exposure to Heated Tobacco Products Aerosol Causes Acute Stress Responses in the Lung of Mouse

In the present study, we evaluated the acute response of mice exposed to IQOS aerosol, a brand-name heated tobacco product (HTP), in the lung tissue. First, the thiobarbituric acid-reactive substances (TBA-RS) value was measured as an index to assess oxidative stress, and a significant increase was observed after exposure, followed by a significant increase in the total lung GSH concentration. The stress responses induced by IQOS aerosols was then analyzed by focusing on the changes in Nrf2 and ATF4, which are transcription factors that induce the expression of genes involved in GSH biosynthesis or metabolism. Although Nrf2 activation was not observed, significant accumulation of ATF4 in the nuclear fraction was noted three hours after exposure to IQOS aerosols. Upon an examination of changes in factors in the GSH biosynthetic system, a significant increase in cystine concentration in the lung tissue was measured, and an increase in xCT expression level was observed in the cell membrane fraction three-six hours after IQOS exposure. Furthermore, characteristic changes in HO-1, a stress-response protein regulated by ATF4, was discovered six hours after IQOS exposure. Moreover, analysis of the upstream ATF4 regulatory system revealed that phosphorylation of eIF2α was enhanced in the lung cytoplasmic fraction three hours after exposure to IQOS aerosols. These findings suggest that ER stress might be induced as an early response to IQOS aerosol exposure, accompanied by the activation of the eIF2α-ATF4 axis. These intracellular changes have also been reported after exposure to combustible cigarette smoke. Thus, the acute response found in the lungs of mice in the present study demonstrate that the inhalation of aerosols from IQOS elicits a biological response similar to that of combustible cigarette smoke. In conclusion, our results provide evidence that the biological effects of HTPs, such as IQOS, cannot be ignored in the lungs.

A Decision-Theoretic Public Health Framework for Heated Tobacco and Nicotine Vaping Products

Markets for nicotine vaping products (NVPs) and heated tobacco products (HTPs) have grown as these products became positioned as harm-reduction alternatives to combusted tobacco products. Herein, we present a public health decision-theoretic framework incorporating different patterns of HTP, NVP, and cigarette use to examine their impacts on population health. Our framework demonstrates that, for individuals who would have otherwise smoked, HTP use may provide public health benefits by enabling cessation or by discouraging smoking initiation and relapse. However, the benefits are reduced if more harmful HTP use replaces less harmful NVP use. HTP use may also negatively impact public health by encouraging smoking by otherwise non-smokers or by encouraging initiation or relapse into smoking. These patterns are directly influenced by industry behavior as well as public policy towards HTPs, NVPs, and cigarettes. While substantial research has been devoted to NVPs, much less is known about HTPs. Better information is needed to more precisely define the health risks of HTPs compared to cigarettes and NVPs, the relative appeal of HTPs to consumers, and the likelihood of later transitioning to smoking or quitting all products. While our analysis provides a framework for gaining that information, it also illustrates the complexities in distinguishing key factors.

Heated tobacco products and circulating high-density lipoprotein cholesterol concentrations

We aimed to assess the association between heated tobacco product (HTP) use and high-density lipoprotein cholesterol (HDL-C) concentration. Our study included 12,268 workers from five companies (Study I) and 36,503 workers from another large company (Study II). Participants were categorized into five groups: never smokers, past smokers, exclusive HTP users, dual users of cigarettes and HTPs, and exclusive cigarette smokers. We analyzed the data of Studies I and II separately and then pooled these estimates using a fixed-effect model. Of the 48,771 participants, 9.3% were exclusive HTP users, and 6.0% were dual users. Exclusive HTP users had modestly but significantly lower concentrations of HDL-C than never smokers, with the pooled mean difference being - 1.1 (95% CI - 1.5 to - 0.6) mg/dL. Dual users showed a further reduction (mean difference - 3.7 (- 4.2 to - 3.2) mg/dL), which was comparable to that of exclusive cigarette smokers versus never smokers (mean difference - 4.3 (- 4.7 to - 3.9) mg/dL). The pooled odds ratios (95% CIs) of having low HDL-C (< 40 mg/dL for men and 50 mg/dL for women) were 1, 0.99 (0.90-1.11), 1.25 (1.09-1.43), 2.02 (1.76-2.32), and 2.09 (1.88-2.32) for never smokers, past smokers, exclusive HTP users, dual users, and exclusive cigarette smokers, respectively. In conclusion, exclusive HTP users had lower HDL-C concentrations than never smokers, although higher than exclusive cigarette smokers. Moreover, dual users had HDL-C concentrations similar to those in exclusive cigarette smokers.