Chemical characterisation and cytotoxic analysis of an electronic cigarette and heated tobacco product compared to a conventional cigarette in human lung cell lines.

Comparison of PAHs behaviors in the pyrolysis products of oily sludge with different ash contents

Heated tobacco products (HTPs) are novel products that allow users to inhale nicotine by heating (350 °C) reconstituted tobacco rather than combustion (900 °C) as in conventional cigarettes. HTP sticks containing reconstituted tobacco come in various flavours such as menthol, citrus, etc., like electronic cigarette liquids. Thus, the composition of HTP aerosol will also vary according to the flavouring agents added. Overall, the content of toxic chemicals in HTP aerosol appears to be lower than in cigarette smoke. However, the concentrations of more than twenty harmful and potentially harmful constituents have been reported to be higher in HTP aerosol than in cigarette smoke. Further, several toxic compounds not detected in cigarette smoke are also reported in HTP aerosol. Thus, the risks of HTP use remain unknown. Most of the available data on the composition and health effects of mainstream HTP aerosol exposure are generated by the tobacco industry. Few independent studies have reported short-term pathophysiological effects of HTP use. Currently available HTP toxicity data are mainly on the pulmonary and cardiovascular systems. Moreover, there are no long-term toxicity data and, therefore, the claims of the tobacco industry regarding HTPs as a safer alternative to traditional combustible cigarettes are unsubstantiated. Furthermore, HTP aerosol contains the highly addictive substance nicotine, which is harmful to the adolescent brain, developing foetuses, pregnant women, and also adults. Hence, comprehensive studies addressing the safety profiling related to long-term HTP use are warranted. With this background, the following review summarizes the current state of knowledge on HTP toxicity on four broad lines: composition of mainstream HTP aerosol compared to traditional combustible cigarette smoke, biomarkers of HTP exposure, health effects of HTP exposure, and the harm reduction aspect.

Comparison of the chemical composition of aerosols from heated tobacco products, electronic cigarettes and tobacco cigarettes and their toxic impacts on the human bronchial epithelial BEAS-2B cells

The differences in aerosol composition between new tobacco types (heated tobacco products and electronic cigarettes) and conventional cigarettes have not been systematically studied. In this study, the emissions of volatile organic compounds (VOCs), carbon monoxide (CO), nicotine, and tar from heated tobacco products (HTPs), electronic cigarettes (e-cigarettes) and conventional cigarettes were compared, and their health risks were evaluated by applying the same smoking regime and a loss mechanism of smoking. Twenty VOCs were identified in aerosols from HTPs, 18 VOCs were identified in aerosols from e-cigarettes, and 97 VOCs were identified in aerosols from cigarettes by GC–MS and HPLC analysis. The concentrations of total VOCs (TVOCs) emitted by the three types of tobacco products decreased as follows: e-cigarettes (795.4 mg/100 puffs) > cigarettes (83.29 mg/100 puffs) > HTPs (15.65 mg/100 puffs). The nicotine content was 24.63 ± 2.25 mg/100 puffs for e-cigarettes, 22.94 ± 0.03 mg/100 puffs for cigarettes, and 8.817 ± 0.500 mg/100 puffs for HTPs. When using cigarettes of the same brand, the mass concentrations of VOCs, tar, and CO emitted by HTPs were approximately 81.2%, 95.9%, and 97.5%, respectively, lower than the amounts emitted by cigarettes. The health risk results demonstrated that the noncarcinogenic risk of the three types of tobacco products decreased as follows: cigarettes (3609.05) > HTPs (2449.70) > acceptable level (1) > e-cigarettes (0.91). The lifetime cancer risk (LCR) decreased as follows: cigarettes (2.99 × 10−4) > HTPs (9.92 × 10−5) > e-cigarettes (4.80 × 10−5) > acceptable level (10−6). In general, HTPs and e-cigarettes were less harmful than cigarettes when the emission of VOCs and CO was considered.

A single and short exposure to heated tobacco vapor or cigarette smoke affects macrophage activation and polarization

Immunotoxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor on Jurkat T cell functions.

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. 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. 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. 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. 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.

Tobacco smoke harbors toxic combustion by-products contributing to inflammatory diseases. Cigarette smoke's impact on ocular diseases has been poorly characterized, despite conjunctival mucosa's sensitivity to these toxicants. Of note, cigarette smoke triggers redness, tearing, and discomfort, accounting as a risk factor for glaucoma, macular degeneration, cataracts, and other eye conditions. Low quit rates of cessation highlight the need for alternatives. Heated tobacco products (HTPs), may represent a less toxic alternative for those smokers. This study evaluates cigarette smoke and HTPs effects on cornea under standard and clinically relevant conditions. Corneal tissues collected from donors and in vitro model in two different cell lines of corneal epithelium were exposed to cigarette (1R6F) smoke and HTPs vapor. Air exposure was included as a control. Tissue pathological evaluation was carried out by hematoxylin and eosin staining. Reactive oxygen species (ROS) were measured, and quantitative PCR assessed inflammatory and antioxidant genes expression. Proteome analysis was used to evaluate differentially expressed proteins related to the oxidative stress. Scratch assay measured smoke and HTPs impact on cells. Hematoxylin & eosin staining highlighted that cigarette smoke impairs corneal tissue integrity, leading to ROS accumulation and inflammation, as proved by qPCR analysis. Proteomic analysis showed that corneal tissue's proteins were differently oxidized by the different experimental conditions. HTP targeted structural intracellular proteins, whereas 1R6F affects different members of collagen family. Finally, cigarette smoke, but not HTPs, impairs epithelial cells wound closure. Smoking increases oxidative stress, leading to significant corneal damage and inflammation. HTPs may offer a less toxic alternative.

Comparison of carbonyls and tobacco-specific nitrosamines in aerosols of heated tobacco products and conventional cigarette smoke using both targeted and untargeted analytical methods.

Cigarette smoke extract (CSE) was obtained from CCs (Marlboro, Philip Morris) and HTPs (Marlboro Heat Sticks Regular for IQOS, Philip Morris) and initiated a wound-healing assay with a cell-free area created in the centre of a titanium plate by sticking a 2-mm-width line tape. The L929 mouse fibroblast cells were exposed with 2.5 and 5% CSE from HTPs and CCs and then seeded in the titanium plate. A scratch wound-healing assay was initiated when all samples were at 80% confluence. The number of cells migrating to the wound site was counted after 12, 24, and 48h. Cell migration decreased after CSE exposure from both CCs and HTPs. At each time-point with 2.5% CSE, cell migration in the HTP group was less than that of the CC group. There were significant differences between the 2.5% CC and 2.5% HTP groups and the 5% CC and 5% HTP groups after 24h. HTPs and CCs had similar effects in the wound-healing assay. Therefore, HTP use may be a risk factor for poor dental implant healing.

Heated tobacco products (HTPs) are marketed as lower-risk alternatives to conventional cigarettes; however, their toxicological impacts remain insufficiently characterized. This study evaluated the effects of HTP emissions on gene expression and mitochondrial function in comparison with conventional cigarettes. Whole cigarette smoke condensates (WCSCs), comprising both gas and particulate phases, were prepared from three commercially available HTPs and from 3R4F reference cigarettes. Human lung epithelial BEAS-2B cells were exposed to WCSCs at 3 μg nicotine/mL for 24 h, followed by transcriptome profiling using RNA sequencing. Principal component analysis demonstrated that HTP-WCSCs induced weaker gene expression changes than 3R4F-WCSC, with only modest variation among HTPs. Gene set enrichment analysis revealed that both HTP- and 3R4F-WCSCs significantly downregulated oxidative phosphorylation (OXPHOS)–related pathways, indicating potential mitochondrial impairment. Functional assays confirmed that both exposures elevated mitochondrial reactive oxygen species (ROS), while mitochondrial morphology, ATP production, membrane potential, and cytosolic ROS were largely unaffected. Collectively, these results show that although HTP emissions elicit weaker transcriptomic perturbations than conventional cigarette emissions, both converge on mitochondrial targets by suppressing OXPHOS gene expression and increasing mitochondrial ROS. Mitochondrial dysfunction may therefore represent a common mechanism underlying tobacco product toxicity.

BackgroundIndependent studies on exhaled carbon monoxide (CO) and saliva cotinine levels in regular heated tobacco product (HTP) users, and how they compare with conventional cigarette (CC) smokers, are lacking.MethodsA total...

Acrylamide levels in smoke from conventional cigarettes and heated tobacco products and exposure assessment in habitual smokers

The article highlights key features of entheses relevant to understanding psoriatic arthritis (PsA). It is emphasized that entheses are regions of stress concentration and that stress levels are reduced by anatomical adaptations at the insertion site and its adjoining tissues. These adaptations for stress dissipation include fascial expansions, the flaring out of soft tissue as it approaches the enthesis, the reduction of insertional angle changes by pulleys or retinacula, and fibrocartilage buffers near the bony interface. Despite such adaptations, however, microdamage is common at entheses and can be associated with the presence of microscopic cellular infiltrates, including macrophages and lymphocytes that can be seen as a normal age-related finding. Observations pertaining to the close functional interdependence between the enthesis and adjacent synovium have led to the concept of a synovio-entheseal complex, which is important for understanding joint physiology and pathophysiologic mechanisms of synovitis in PsA.

Review and comparative analysis of the particulate matter generated in conventional cigarettes and heated tobacco products - mainstream and environmental emissions