Mechanisms of toxicity and biomarkers of flavoring and flavor enhancing chemicals in emerging tobacco and non-tobacco products

Free Radicals in Little Cigar Mainstream Smoke and the Potential Influence of Flavoring Chemicals on Free Radical Production

Implementation of the Tobacco Control Act in 2009 banned characterizing flavors in cigarettes (except menthol and tobacco), but substitution has occurred by the continued availability of alternative flavored products (i.e., flavored little cigars). Little is known about how flavorants in noncigarette tobacco products impact human health. Thus, we investigated the impact of flavorants on free radical production in the mainstream smoke of little cigars. Gas- and particulate-phase free radical yields in mainstream smoke generated from 12 commercial little cigar brands and research little cigars and cigarettes were measured via electron paramagnetic resonance spectroscopy using the International Organization of Standardization (ISO) smoking protocol. Flavorants were extracted from unsmoked little cigars and analyzed by gas chromatography-mass spectroscopy. Gas- and particulate-phase radical yields from little cigars ranged from 13.5 to 97.6 and 0.453-1.175 nmol/unit, respectively. Comparatively, research cigarettes yielded an average of 4.9 nmol gas-phase radicals/unit and 0.292 nmol particulate-phase radicals/unit. From the products, 66 flavorants were identified, with each brand containing 4-24 individual flavorants. The free radical content was strongly correlated with the number of flavorants present in each cigar (r = 0.74, p = 0.01), indicating that highly flavored little cigars may produce higher levels of toxic free radicals. The presence of the flavorant ethyl methylphenylglycidate (strawberry) was associated with >2-fold higher levels of GP radicals (p = 0.001). Our results show that free radical delivery from little cigars is greater than that from research cigarettes and provide empirical evidence for the harmfulness of flavored tobacco products. Additionally, it demonstrates that flavorants present in combustible tobacco products can influence the levels of free radicals produced. Therefore, future tobacco product standards should consider little cigars.

Fruit flavors in electronic cigarettes (ECIGs) are associated with nocturnal dry cough: A population longitudinal analysis

Evidence from in vitro and animal models has identified the pulmonary toxicity of flavors in electronic cigarettes (ECIGs); however, less is known from epidemiological studies about the effects of flavors in the respiratory health. This study examined the longitudinal association between exposure to ECIGs flavors and nocturnal dry cough among ECIGs users. A secondary analysis of data from the Population Assessment of Tobacco and Health Study (2014-2019) was conducted. The study population included adults who provided information (n = 18,925) for a total of 38,638 observations. Weighted-incidence estimates and weighted- generalized estimating equation models were performed to assess unadjusted and adjusted associations. The weighted incidence proportion (WIP) of nocturnal dry cough was significantly higher among current (WIP:16.6%; 95%CI 10.5, 21.2) and former fruit flavored ECIGs users (WIP:16.6%; 95%CI 11.3, 21.9) as compared to non-ECIGs users (WIP:11.1%; 95%CI 10.6, 11.6). Current ECIGs users of fruit flavors showed 40% higher risk of reporting cough than non-ECIGs users (aRR:1.40, 95%CI 1.01, 1.94). Former ECIGs users of multiple flavors and other flavors had 300% and 66% higher risk to develop cough, respectively (aRR:3.33, 95%CI 1.51, 7.34 and aRR:1.66, 95%CI 1.0.9, 2.51), relative to non-ECIGs users. We observed a significantly higher risk of developing nocturnal dry cough in the past 12 months in current and former ECIGs users of fruit flavors and in former ECIGs users of multiple flavors. To the extent that cough may serve as an early indicator of respiratory inflammation and potential disease risk, the association between ECIGs use and cough raises potential concerns.

Seeking to be seen as legitimate members of the scientific community? An analysis of British American Tobacco and Philip Morris International's involvement in scientific events

INTRODUCTION

For decades, tobacco companies manipulated and misused science. They funded and disseminated favourable research and suppressed research that showed the harms of their products, deliberately generating misinformation. While previous work has examined many of the practices involved, their engagement in scientific events has so far not been systematically studied. Here, we examine the involvement of British American Tobacco (BAT) and Philip Morris International (PMI) in scientific events, including conferences, symposia and workshops.

METHODS

Our analysis involved two steps. First, we collected all available data PMI and BAT provided on their websites to identify events. Second, we extracted information about the nature of tobacco industry involvement from event websites and materials.

RESULTS

We identified 213 scientific events that BAT and/or PMI representatives attended between April 2012 and September 2021. Most events took place in high-income countries in Europe and North America. They covered a diverse range of fields, including toxicology (n=60, 28.1%), medicine (n=25, 11.7%), biology (n=24, 11.3%), chemistry (n=23, 10.8%) and aerosol science (n=18, 8.5%), as well as dentistry (n=9, 4.2%), pharmaceutical science (n=8, 3.8%) and computing (n=8, 3.8%). We identified 356 posters provided by BAT and PMI that linked to 118 events (55.4%) as well as 77 presentations from 65 events (30.5%). Industry involvement through sponsorship (nine events), exhibition (three events) or organising committee (one event) was rare.

CONCLUSION

BAT and PMI representatives attended a large number and wide range of scientific events. Given that scientific events could be a crucial platform for building connections in the scientific sphere and disseminating industry's messages, this work highlights the importance of denormalising the tobacco industry's involvement in scientific events.

e-Cigarette Tobacco Flavors, Public Health, and Toxicity: Narrative Review

BACKGROUND

Recently, the US Food and Drug Administration implemented enforcement priorities against all flavored, cartridge-based e-cigarettes other than menthol and tobacco flavors. This ban undermined the products' appeal to vapers, so e-cigarette manufacturers added flavorants of other attractive flavors into tobacco-flavored e-cigarettes and reestablished appeal.

OBJECTIVE

This review aims to analyze the impact of the addition of other flavorants in tobacco-flavored e-cigarettes on both human and public health issues and to propose further research as well as potential interventions.

METHODS

Searches for relevant literature published between 2018 and 2023 were performed. Cited articles about the toxicity of e-cigarette chemicals included those published before 2018, and governmental websites and documents were also included for crucial information.

RESULTS

Both the sales of e-cigarettes and posts on social media suggested that the manufacturers' strategy was successful. The reestablished appeal causes not only a public health issue but also threats to the health of individual vapers. Research has shown an increase in toxicity associated with the flavorants commonly used in flavored e-cigarettes, which are likely added to tobacco-flavored e-cigarettes based on tobacco-derived and synthetic tobacco-free nicotine, and these other flavors are associated with higher clinical symptoms not often induced solely by natural, traditional tobacco flavors.

CONCLUSIONS

The additional health risks posed by the flavorants are pronounced even without considering the toxicological interactions of the different tobacco flavorants, and more research should be done to understand the health risks thoroughly and to take proper actions accordingly for the regulation of these emerging products.

Flow Rate and Wall Shear Stress Characterization of a Biomimetic Aerosol Exposure System

Current in vitro emissions and exposure systems lack biomimicry, use unrealistic flow conditions, produce unrealistic dose, and provide inaccurate biomechanical cues to cell cultures, limiting ability to correlate in vitro outcomes with in vivo health effects. A biomimetic in vitro system capable of puffing aerosol and clean air inhalation may empower researchers to investigate complex questions related to lung injury and disease. A biomimetic aerosol exposure system (BAES), including an electronic cigarette adapter, oral cavity module (OCM), and bifurcated exposure chamber (BEC) was designed and manufactured. The fraction of aerosol deposited in transit to a filter pad or lost as volatiles was 0.116±0.021 in a traditional emissions setup versus 0.098 ± 0.015 with the adapter. The observed flowrate was within 5% of programed flowrate for puffing (25 mL/s), puff-associated respiration (450 mL/s), and tidal inhalation (350 mL/s). The maximum flowrate observed in the fabricated BAES was 450 mL/s, exceeding the lower target nominal wall shear stress of 0.025 Pa upstream of the bifurcation and fell below the target of 0.02 Pa downstream. This in vitro system addresses several gaps observed in commercially available systems and may be used to study many inhaled aerosols. The current work illustrates how in silico models may be used to correlate results of an in vitro study to in vivo conditions, rather than attempting to design an in vitro system that performs exactly as the human respiratory tract.

Abnormal expression profile of plasma exosomal microRNAs in exclusive electronic cigarette adult users

Background

Exposure to electronic cigarette (e-cigarette) aerosol has been linked to several health concerns, including DNA damage, elevated oxidative stress, the release of inflammatory cytokine, and dysfunctions in epithelial barriers. However, little is known about the effect of exclusive e-cigarette use on expression profiles of exosomal miRNAs, which play critical regulatory roles in many inflammatory responses and disease processes including cancer. We aim to compare the exosomal microRNA expression profile between exclusive e-cigarette users and normal controls without any tobacco product use (non-users).

Methods

Using plasma samples from 15 exclusive e-cigarette users and 15 non-users in the Population Assessment of Tobacco and Health (PATH) Wave 1 study (2013-2014), we examined exosomal microRNAs expression levels through Illumina NextSeq 500/550 sequencing. The differential analyses between exclusive e-cigarette users and non-users were examined using the generalized linear model approach in the DESeq2 package in R/Bioconductor after adjusting the significant confounding effect from race. Gene enrichment analyses were conducted on target genes regulated by significant microRNAs in the differential analyses. Further, molecular-based techniques using the micro RNA mimics and inhibitors were applied for the validation of the expressions of the micro RNAs in vitro.

Results

We identified four microRNAs that have significantly higher expression levels in exclusive e-cigarette users than non-users including hsa-miR-100-5p, hsa-miR-125a-5p, hsa-miR-125b-5p, and hsa-miR-99a-5p. GO enrichment analysis on the target genes regulated by the four microRNAs showed that dysregulation of the four microRNAs in exclusive e-cigarette users involved in multiple cell processes such as protein kinase binding and miRNA metabolic process. KEGG pathway enrichment analysis found the four upregulated miRNAs in exclusive e-cigarette users involved in many cancer pathways such as the non-small cell lung cancer, small cell lung cancer, pancreatic cancer, p53 signaling pathway, Hippo signaling pathway, HIF-1 signaling pathway, and MAPK signaling pathway. Overexpression of miRNA hsa-miR-125b-5p was shown to promote DNA damage in bronchial epithelia cells.

Conclusions

Four plasma exosomal microRNAs involved in cancer development had higher expression levels in exclusive e-cigarette users than non-users, which might indicate a potentially elevated risk of cancer among exclusive e-cigarette users.

Tobacco and menthol flavored nicotine-free electronic cigarettes induced inflammation and dysregulated repair in lung fibroblast and epithelium

BACKGROUND

Electronic cigarette (e-cig) vaping has increased in the past decade in the US, and e-cig use is misleadingly marketed as a safe cessation for quitting smoking. The main constituents in e-liquid are humectants, such as propylene glycol (PG) and vegetable glycerine (VG), but different flavoring chemicals are also used. However, the toxicology profile of flavored e-cigs in the pulmonary tract is lacking. We hypothesized that menthol and tobacco-flavored e-cig (nicotine-free) exposure results in inflammatory responses and dysregulated repair in lung fibroblast and epithelium.

METHOD

We exposed lung fibroblast (HFL-1) and epithelium (BEAS-2B) to Air, PG/VG, menthol flavored, or tobacco-flavored e-cig, and determined the cytotoxicity, inflammation, and wound healing ability in 2D cells and 3D microtissue chip models.

RESULTS

After exposure, HFL-1 showed decreased cell number with increased IL-8 levels in the tobacco flavor group compared to air. BEAS-2B also showed increased IL-8 secretion after PG/VG and tobacco flavor exposure, while menthol flavor exposure showed no change. Both menthol and tobacco-flavored e-cig exposure showed decreased protein abundance of type 1 collagen α 1 (COL1A1), α-smooth-muscle actin (αSMA), and fibronectin as well as decreased gene expression level of αSMA (Acta2) in HFL-1. After tobacco flavor e-cig exposure, HFL-1 mediated wound healing and tissue contractility were inhibited. Furthermore, BEAS-2B exposed to menthol flavor showed significantly decreased tight junction gene expressions, such as CDH1, OCLN, and TJP1.

CONCLUSION

Overall, tobacco-flavored e-cig exposure induces inflammation in both epithelium and fibroblasts, and tobacco-flavored e-cig inhibits wound healing ability in fibroblasts.

Acetal Formation of Flavoring Agents with Propylene Glycol in E-Cigarettes: Impacts on Indoor Partitioning and Thirdhand Exposure

The widespread use of flavored e-cigarettes has led to a significant rise in teenage nicotine use. In e-liquids, the flavor carbonyls can form acetals with unknown chemical and toxicological properties. These acetals can cause adverse health effects on both smokers and nonsmokers through thirdhand exposure. This study aims to explore the impacts of these acetals formed in e-cigarettes on indoor partitioning and thirdhand exposure. Specifically, the acetalization reactions of commonly used flavor carbonyls in laboratory-made e-liquids were monitored using proton nuclear magnetic resonance (1H NMR) spectroscopy. EAS-E Suite and polyparameter linear free energy relationships (PP-LFERs) were employed to estimate the partitioning coefficients for species. Further, a chemical two-dimensional partitioning model was applied to visualize the indoor equilibrium partitioning and estimate the distribution of flavor carbonyls and their acetals in the gas phase, aerosol phase, and surface reservoirs. Our results demonstrate that a substantial fraction of carbonyls were converted into acetals in e-liquids and their chemical partitioning was significantly influenced. This study shows that acetalization is a determinant factor in the exposure and toxicology of harmful carbonyl flavorings, with its impact extending to both direct exposure to smokers and involuntary exposure to nonsmokers.

E-cigarette exposure causes early pro-atherogenic changes in an inducible murine model of atherosclerosis

Introduction: Evidence suggests that e-cigarette use (vaping) increases cardiovascular disease risk, but decades are needed before people who vape would develop pathology. Thus, murine models of atherosclerosis can be utilized as tools to understand disease susceptibility, risk and pathogenesis. Moreover, there is a poor understanding of how risk factors for atherosclerosis (i.e., hyperlipidemia, high-fat diet) intersect with vaping to promote disease risk. Herein, we evaluated whether there was early evidence of atherosclerosis in an inducible hyperlipidemic mouse exposed to aerosol from commercial pod-style devices and e-liquid. Methods: Mice were injected with adeno-associated virus containing the human protein convertase subtilisin/kexin type 9 (PCSK9) variant to promote hyperlipidemia. These mice were fed a high-fat diet and exposed to room air or aerosol derived from JUUL pods containing polyethylene glycol/vegetable glycerin (PG/VG) or 5% nicotine with mango flavoring for 4 weeks; this timepoint was utilized to assess markers of atherosclerosis that may occur prior to the development of atherosclerotic plaques. Results: These data show that various parameters including weight, circulating lipoprotein/glucose levels, and splenic immune cells were significantly affected by exposure to PG/VG and/or nicotine-containing aerosols. Discussion: Not only can this mouse model be utilized for chronic vaping studies to assess the vascular pathology but these data support that vaping is not risk-free and may increase CVD outcomes later in life.

E-Cigarettes and Associated Health Risks: An Update on Cancer Potential

The potential cancer risk associated with electronic-cigarette (e-cigarette) use is ongoing and remains a subject of debate. E-Cigarettes work by heating a liquid that usually contains nicotine, flavorings, and other chemicals. When the liquid is heated, users inhale an aerosol into their lungs. While e-cigarettes are generally considered less harmful than traditional tobacco products, they still contain potentially harmful chemicals, which can damage DNA and lead to cancer. Several studies have investigated the potential cancer risk associated with e-cigarette use, while other studies have suggested that e-cigarette aerosol may contain carcinogenic chemicals that could increase the risk of lung and bladder cancer in humans. However, these studies are limited in their scope and do not provide conclusive evidence. Overall, the long-term cancer risk associated with e-cigarette use remains uncertain, more research is needed to fully understand the potential risks and benefits of e-cigarettes. However, this review will allow the investigator to get more recent updates about e-cigarettes.

Impact of the Tobacco Heating System and Cigarette Smoking on the Oral Cavity: A Pilot Study

Cigarette smoking and the harmful chemicals released during smoking have negative effects on oral health. As a measure of harm reduction, a new alternative tobacco heating system (THS) has been developed. The aim of the study was to analyze and compare the effects of conventional cigarettes and THS on the oral mucosa, the salivary flow rate (SFR), halitosis, and the load of Candida spp. The study included 20 tobacco heating smokers, 20 conventional cigarette smokers, and 20 nonsmokers. The subjects completed questionnaires on medical information, smoking habits, oral lesions, and symptoms. A clinical examination and SFR test were performed on each subject, followed by an organoleptic assessment of halitosis. Mucosal swabs were collected and cult ured to identify Candida spp. Significant differences were found between the smoking groups in relation to halitosis (p < 0.001; ε2 = 0.624), intraoral findings (p < 0.001; ε2 = 0.507), SFR (p < 0.001; ε2 = 0.0331) and dry mouth for subjective complaints (p = 0.021; ε2 = 0.363). The SFR was significantly lower; however, halitosis, the prevalence of intraoral findings, and dry mouth were significantly higher among smokers, but there were no significant differences between THS and conventional smokers. The present study suggests that THS smoking has similar effects on oral tissues, especially the SFR and halitosis, as conventional cigarette smoking.

Heated Tobacco Products: Insights into Composition and Toxicity

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.

Tobacco and Menthol flavored electronic cigarettes induced inflammation and dysregulated repair in lung fibroblast and epithelium

Background

Electronic cigarette (e-cig) vaping has increased in the past decade in the US, and e-cig use is misleadingly marketed as a safe cessation for quitting smoking. The main constituents in e-liquid are humectants, such as propylene glycol (PG) and vegetable glycerine (VG), but different flavoring chemicals are also used. However, the toxicology profile of flavored e-cigs in the pulmonary tract is lacking. We hypothesized that menthol and tobacco-flavored e-cig (nicotine-free) exposure results in inflammatory responses and dysregulated repair in lung fibroblast and epithelium.

Method

We exposed lung fibroblast (HFL-1) and epithelium (BEAS-2B) to Air, PG/VG, menthol flavored, or tobacco-flavored e-cig, and determined the cytotoxicity, inflammation, and wound healing ability of the cells in a microtissue chip model.

Results

After exposure, HFL-1 showed decreased cell number with increased IL-8 levels in the tobacco flavor group compared to air. BEAS-2B also showed increased IL-8 secretion after PG/VG and tobacco flavor exposure, while menthol flavor exposure showed no change. Both menthol and tobacco-flavored e-cig exposure showed decreased protein abundance of type 1 collagen (COL1A1), α-smooth-muscle actin (αSMA), and fibronectin as well as decreased gene expression level of αSMA (Acta2) in HFL-1. After tobacco flavor e-cig exposure, HFL-1 mediated wound healing and tissue contractility were inhibited. Furthermore, BEAS-2B exposed to menthol flavor showed significantly decreased gene expression of CDH1, OCLN, and TJP1.

Conclusion

Overall, tobacco-flavored e-cig exposure induces inflammation in both epithelium and fibroblasts, and tobacco-flavored e-cig inhibits wound healing ability in fibroblast.

A Research Agenda to Inform Cannabis Regulation: How Science Can Shape Policy

In the United States, changes to cannabis policy have outpaced scientific knowledge about cannabis, its effects, and the impacts of different policy approaches. Research barriers stem from key federal policies, including strict drug scheduling of cannabis, which comprehensively hinder the ability to conduct cannabis research, affecting state markets, evidence-based regulation, and scientific gains that could more effectively shape policy moving forward. The Cannabis Regulators Association (CANNRA) is a nonpartisan nonprofit organization that convenes and supports government agencies to facilitate information exchange and learning from existing cannabis regulations across US states and territories and other governmental jurisdictions. This commentary outlines a research agenda that, if implemented, would address critical gaps in the science that cannabis regulators have identified in terms of knowledge regarding: (1) medicinal use of cannabis; (2) cannabis product safety; (3) cannabis consumer behaviors; (4) policies to promote equity and reduce disparities, both in the industry and more broadly in communities affected by the past criminalization of cannabis; (5) policies to prevent youth consumption and promote public health and safety; and (6) policies to reduce the illicit market and associated harms. The research agenda outlined here is the result of both formal discussions through CANNRA-wide meetings and informal discussions cannabis regulators have had as part of CANNRA committees. This research agenda is not all encompassing but rather highlights areas of research that have vital importance for cannabis regulation and policy implementation. Although many organizations weigh in on research needs related to cannabis, cannabis regulators (ie, the individuals implementing policies legalizing cannabis in states and territories) have generally not had a voice at the table advocating for specific research to be conducted. Their perspective representing the government agencies closest to the ground in terms of experiencing the impacts of current cannabis policy is essential to furthering quality, practical research that can advance informed and effective policy.

Pulmonary immune response regulation, genotoxicity, and metabolic reprogramming by menthol- and tobacco-flavored e-cigarette exposures in mice

Menthol and tobacco flavors are available for almost all tobacco products, including electronic cigarettes (e-cigs). These flavors are a mixture of chemicals with overlapping constituents. There are no comparative toxicity studies of these flavors produced by different manufacturers. We hypothesized that acute exposure to menthol and tobacco-flavored e-cig aerosols induces inflammatory, genotoxicity, and metabolic responses in mouse lungs. We compared two brands, A and B, of e-cig flavors (PG/VG, menthol, and tobacco) with and without nicotine for their inflammatory response, genotoxic markers, and altered genes and proteins in the context of metabolism by exposing mouse strains, C57BL/6J (Th1-mediated) and BALB/cJ (Th2-mediated). Brand A nicotine-free menthol exposure caused increased neutrophils and differential T-lymphocyte influx in bronchoalveolar lavage fluid and induced significant immunosuppression, while brand A tobacco with nicotine elicited an allergic inflammatory response with increased Eotaxin, IL-6, and RANTES levels. Brand B elicited a similar inflammatory response in menthol flavor exposure. Upon e-cig exposure, genotoxicity markers significantly increased in lung tissue. These inflammatory and genotoxicity responses were associated with altered NLRP3 inflammasome and TRPA1 induction by menthol flavor. Nicotine decreased surfactant protein D and increased PAI-1 by menthol and tobacco flavors, respectively. Integration of inflammatory and metabolic pathway gene expression analysis showed immunometabolic regulation in T cells via PI3K/Akt/p70S6k-mTOR axis associated with suppressed immunity/allergic immune response. Overall, this study showed the comparative toxicity of flavored e-cig aerosols, unraveling potential signaling pathways of nicotine and flavor-mediated pulmonary toxicological responses, and emphasized the need for standardized toxicity testing for appropriate premarket authorization of e-cigarette products.

Rapid detection of nicotine and benzoic acid in e-liquids with surface-enhanced Raman scattering and artificial intelligence-assisted spectrum interpretation

Electronic cigarettes have rapidly gained acceptance recently. Nicotine-containing electronic cigarette liquids (e-liquids) are prohibited in some countries, but are permitted and simply available online in others. A rapid detection method is therefore required for on-site inspection or screening of a large amount of samples. Our previous study demonstrated a surface-enhanced Raman scattering (SERS)-based approach to identify nicotine-containing e-liquids; without any pre-treatment, e-liquid can be directly tested on our solid-phase SERS substrates, made of silver nanoparticle arrays embedded in anodic aluminium oxide nanochannels (Ag/AAO). However, this approach required manual determination of spectral signatures and negative samples should be validated in the second round detection. Here, after examining 406 commercial e-liquids, we refined this approach by developing artificial intelligence (AI)-assisted spectrum interpretations. We also found that nicotine and benzoic acid can be simultaneously detected in our platform. This increased test sensitivity because benzoic acid is usually used in nicotine salts. Around 64% of nicotine-positive samples in this study showed both signatures. Using either cutoffs of nicotine and benzoic acid peak intensities or a machine learning model based on the CatBoost algorithm, over 90% of tested samples can be correctly discriminated with only one round of SERS measurement. False negative and false positive rates were 2.5-4.4% and 4.4-8.9%, respectively, depending on the interpretation method and thresholds applied. The new approach takes only 1 microliter of sample and can be performed in 1-2 min, suitable for on-site inspection with portable Raman detectors. It could also be a complementary platform to reduce samples that need to be analyzed in the central labs and has the potential to identify other prohibited additives.

Molecular insights into the role of electronic cigarettes in oral carcinogenesis

Electronic cigarette (EC) usage or vaping has seen a significant rise in recent years across various parts of the world. They have been publicized as a safe alternative to smoking; however, this is not supported strongly by robust research evidence. Toxicological analysis of EC liquid and aerosol has revealed presence of several toxicants with known carcinogenicity. Oral cavity is the primary site of exposure of both cigarette smoke and EC aerosol. Role of EC in oral cancer is not as well-researched as that of traditional smoking. However, several recent studies have shown that it can lead to a wide range of potentially carcinogenic molecular events in oral cells. This review delineates the oral carcinogenesis potential of ECs at the molecular level, providing a summary of the effects of EC usage on cancer therapy resistance, cancer stem cells (CSCs), immune evasion, and microbiome dysbiosis, all of which may lead to increased tumor malignancy and poorer patient prognosis. This review of literature indicates that ECs may not be as safe as they are perceived to be, however further research is needed to definitively determine their oncogenic potential.

Pro-inflammatory effects of aerosols from e-cigarette-derived flavoring chemicals on murine macrophages

Macrophages treated with the flavoring chemicals found in flavored electronic cigarettes have been shown to induce an inflammatory response, however, limited data are available on the effect of aerosol exposure to these chemicals. We hypothesized that aerosol exposure to flavoring chemicals found in commercially available flavored e-liquids would result in an increase in pro-inflammatory cytokines in macrophages. Raw264.7 macrophage cell lines were exposed to a low and high dose of propylene glycol/vegetable glycerin (PG/VG) with almond flavoring benzaldehyde (280 μg/ml and 2.1 mg/ml), PG/VG with spicy/clove flavoring eugenol (3.5 mg/ml and 12 mg/ml), or PG/VG with apple flavoring hexyl acetate (500 μg/ml and 2.5 mg/ml). Exposure to PG/VG with 2.1 mg/ml benzaldehyde resulted in a significant increase in KC levels compared to air and PG/VG exposed cells. Exposure to PG/VG with both doses of hexyl acetate resulted in a significant increase in KC and IL-6 levels compared to air exposed cells. Exposure to PG/VG with both doses of eugenol resulted in a significant increase in KC and IL-6 levels compared to air and PG/VG exposed cells. These data indicate the ability of aerosol exposure to e-cigarette flavoring chemicals to significantly increase pro-inflammatory cytokine release in macrophages.

Chronic low-level JUUL aerosol exposure causes pulmonary immunologic, transcriptomic, and proteomic changes

E-cigarettes currently divide public opinion, with some considering them a useful tool for smoking cessation and while others are concerned with potentially adverse health consequences. However, it may take decades to fully understand the effects of e-cigarette use in humans given their relative newness on the market. This highlights the need for comprehensive preclinical studies investigating the effects of e-cigarette exposure on health outcomes. Here, we investigated the impact of chronic, low-level JUUL aerosol exposure on multiple lung outcomes. JUUL is a brand of e-cigarettes popular with youth and young adults. To replicate human exposures, 8- to 12-week-old male and female C57BL/6J mice were exposed to commercially available JUUL products (containing 59 mg/ml nicotine). Mice were exposed to room air, PG/VG, or JUUL daily for 4 weeks. After the exposure period, inflammatory markers were assessed via qRT-PCR, multiplex cytokine assays, and differential cell count. Proteomic and transcriptomic analyses were also performed on samples isolated from the lavage of the lungs; this included unbiased analysis of proteins contained within extracellular vesicles (EVs). Mice exposed to JUUL aerosols for 4 weeks had significantly increased neutrophil and lymphocyte populations in the BAL and some changes in cytokine mRNA expression. However, BAL cytokines did not change. Proteomic and transcriptomic analysis revealed significant changes in numerous biological pathways including neutrophil degranulation, PPAR signaling, and xenobiotic metabolism. Thus, e-cigarettes are not inert and can cause significant cellular and molecular changes in the lungs.

Heat-not-burn tobacco products and cardiovascular risk reduction: A systematic review of randomized controlled trials

BACKGROUND

Heat-not-burn (HNB) technology by the U.S. Food and Drug Administration has been classified as a modified risk tobacco product, which can be a better option for those populations who cannot give up the habit of smoking. The outlook on the effects of these products is quite controversial in the scientific world.

OBJECTIVE

To present the effect of HNB tobacco products on the cardiovascular system, with reference to the existence of possible benefits of the technology.

METHODS

The literature search was conducted in PubMed/Medline, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases, with reliance on a well-defined guiding research statement. Quality appraisal was performed using the CASP checklist for randomized controlled trials.

RESULTS

The search of three databases identified 167 records, and after selection process, 25 randomized controlled trials were eligible for our study's criteria. Twenty studies investigated the effects of HNB products on biomarkers of clinical relevance. Five studies evaluated other functional heart parameters rather than biomarkers.

CONCLUSION

With HNB tobacco products, significant reductions were found in biomarkers of exposure and biological effect related to pathways involved in cardiovascular disease, including inflammation, oxidative stress, lipid metabolism, platelet function, and endothelial dysfunction.

E-cigarette Flavors, Sensory Perception, and Evoked Responses

The chemosensory experiences evoked by flavors encompass a number of unique sensations that include olfactory stimuli (smell), gustatory stimuli (taste, i.e., salty, sweet, sour, bitter, and umami (also known as "savoriness")), and chemesthesis (touch). As such, the responses evoked by flavors are complex and, as briefly stated above, involve multiple perceptive mechanisms. The practice of adding flavorings to tobacco products dates back to the 17th century but is likely much older. More recently, the electronic cigarette or "e-cigarette" and its accompanying flavored e-liquids emerged on to the global market. These new products contain no combustible tobacco but often contain large concentrations (reported from 0 to more than 50 mg/mL) of nicotine as well as numerous flavorings and/or flavor chemicals. At present, there are more than 400 e-cigarette brands available along with potentially >15,000 different/unique flavored products. However, surprisingly little is known about the flavors/flavor chemicals added to these products, which can account for >1% by weight of some e-liquids, and their resultant chemosensory experiences, and the US FDA has done relatively little, until recently, to regulate these products. This article will discuss e-cigarette flavors and flavor chemicals, their elicited responses, and their sensory effects in some detail.

In Vitro Biological Effects of E-Cigarette on the Cardiovascular System-Pro-Inflammatory Response Enhanced by the Presence of the Cinnamon Flavor

The potential cardiovascular effects of e-cigarettes remain largely unidentified and poorly understood. E-liquids contain numerous chemical compounds and can induce exposure to potentially toxic ingredients (e.g., nicotine, flavorings, etc.). Moreover, the heating process can also lead to the formation of new thermal decomposition compounds that may be also hazardous. Clinical as well as in vitro and in vivo studies on e-cigarette toxicity have reported potential cardiovascular damages; however, results remain conflicting. The aim of this study was to assess, in vitro, the toxicity of e-liquids and e-cigarette aerosols on human aortic smooth muscle cells. To that purpose, cells were exposed either to e-liquids or to aerosol condensates obtained using an e-cigarette device at different power levels (8 W or 25 W) to assess the impact of the presence of: (i) nicotine, (ii) cinnamon flavor, and (iii) thermal degradation products. We observed that while no cytotoxicity and no ROS production was induced, a pro-inflammatory response was reported. In particular, the production of IL-8 was significantly enhanced at a high power level of the e-cigarette device and in the presence of the cinnamon flavor (confirming the suspected toxic effect of this additive). Further investigations are required, but this study contributes to shedding light on the biological effects of vaping on the cardiovascular system.

Indoor partitioning and potential thirdhand exposure to carbonyl flavoring agents added in e-cigarettes and hookah tobacco

Flavoring agents added to the e-cigarettes and hookah tobacco have increased the attractiveness of novel nicotine products. Many widely used flavorings are carbonyls, which are toxic to humans. In an indoor environment, residents can be exposed to such harmful flavorings previously emitted to the surrounding environment, through a process termed thirdhand exposure. The recent discovery of a large volume of indoor reservoirs emphasizes the importance of indoor partitioning, which is responsible for thirdhand exposure. Indoor partitioning can be expressed with partitioning coefficients, such as Henry's law solubility constant (H). However, reliable H values for many key flavorings are currently lacking. To better understand their environmental behavior, this study experimentally determined the effective Henry's law constant (Hcps,eff) using the inert gas stripping (IGS) method. Further, the influence of the hydration process for target flavorings was quantified using proton nuclear magnetic resonance (¹H NMR) spectroscopy. We found that hydration of α-dicarbonyls (diacetyl and 2,3-pentanedione) enhanced their Hcps,eff from their intrinsic Henry's law constant (Hcps) by a factor of 3.52 and 2.88, respectively. The two-dimensional partitioning plots were employed to simulate the indoor phase distribution and evaluate the pathways of human exposure. Our findings show that the indoor partitioning of many harmful flavorings is highly sensitive to temperature and the size of indoor reservoirs, indicating that residents are likely to experience third-hand exposure.

Sais de Nicotina e Nicotina Sintética: Novos Desafios para um Velho Problema

O tabagismo é reconhecido como uma doença crônica causada pela dependência à nicotina, presente nos produtos à base de tabaco, e está ligado a uma série de doenças tabaco-relacionadas. Somando-se a isso, é considerada uma doença pediátrica. No Brasil, o tratamento para a cessação do tabagismo desde 2004 é oferecido em todos os níveis de complexidade pelo Sistema Único de Saúde (SUS), contudo, os protocolos internacionalmente utilizados parecem ter limitações significativas quando utilizados em populações tabagistas de crianças e adolescentes. Os sais de nicotina apresentam um menor grau de irritação e impacto na boca e na garganta causado pela nicotina, possibilitando o uso de concentrações maiores de nicotina. A nicotina sintética tem se mostrado a cada dia mais viável economicamente falando e já existem no mercado produtos que se utilizam dessa forma de nicotina, entretanto, poucos estudos foram conduzidos no sentido de avaliar seus impactos à saúde. As novas formas de nicotina e sua forma sintética, associadas com produtos com design atraente, especialmente para os mais jovens, trazem desafios técnicos consideráveis para os profissionais da saúde, pois desconhece-se, no momento, protocolos eficazes para tratar a dependência à nicotina originada dessas novas formas de consumo.

Flavour loyalty may predict cessation or substitution following a cigarillo flavour ban among young adults in the USA

Significance

The purpose of this research was to measure flavour loyalty and identify how current cigarillo users may respond to a hypothetical flavour ban in the USA.

Methods

Cigarillo users aged 21–28 (n=531) were recruited between October 2020 and April 2021 to participate in an online survey. Respondents categorised their preferred, usual and current cigarillo flavours. Individuals who preferred tobacco flavours were compared with individuals who preferred any other flavours. Strength of preferences, or flavour loyalty, was defined when an individual’s preferred flavour matched what they use both usually and currently creating a spectrum of individuals with a strong tobacco preference (n=34), weak tobacco preference (n=20), weak flavour preference (n=162) and strong flavour preference (n=315). Those preferring tobacco were aggregated into any tobacco preference (n=54).

Results

Individuals who preferred any flavour scored higher on a scale of nicotine dependence. There was a dose–response relationship in those who said they would discontinue cigarillos if flavoured options were not available: 11.4% of individuals with any tobacco flavour preference, 27.8% of those with a weak flavour preference and 38.1% of those with a strong flavour preference. A similar trend was noted among those who would switch to another product: 19.2% of those with tobacco flavour preference, 34.3% of those with a weak flavour preference and 43.2% of those with a strong flavour preference.

Conclusion

Individuals who display strong flavour preferences were more likely to say they would discontinue use or seek out alternative flavoured products following a ban on flavoured cigarillos.

Impact of the FDA flavour enforcement policy on flavoured electronic cigarette use behaviour changes

INTRODUCTION

This study aims to investigate electronic cigarette (e-cigarette) use behaviour changes after the implementation of the US Food and Drug Administration (FDA) restriction on the sale of all unauthorised flavoured cartridge-based e-cigarettes other than tobacco and menthol flavour on 6 February 2020, as well as factors associated with these changes.

METHODS

Through Amazon's Mechanical Turk service, 3533 current adult flavoured e-cigarette users (who were not exclusive tobacco-flavoured or menthol-flavoured e-cigarette users) were recruited for an online survey from 8 July to 29 July 2021. Multiple logistic regression models were used to identify significant factors associated with quitting e-cigarette use, switching to other flavoured electronic nicotine delivery system (ENDS) products, switching to combustible tobacco products, switching to menthol-flavoured e-cigarettes and switching to tobacco-flavoured e-cigarettes.

RESULTS

Resulting from the FDA flavour enforcement policy, the top four e-cigarette use behaviour changes were: (1) switching to other flavoured ENDS products such as the tank system or disposable e-cigarettes (29.24%), (2) switching to menthol-flavoured pod systems (18.09%), (3) switching to combustible tobacco products (14.12%) and (4) switching to tobacco-flavoured pod systems (12.03%). There were 4.9% participants who indicated that they quit e-cigarette use. Overall, multiple factors, especially past 30-day use of certain flavours, were associated with different behaviour changes.

CONCLUSIONS

The implementation of the FDA flavour enforcement policy on cartridge-based e-cigarette was associated with significant e-cigarette behaviour changes, with multiple factors being associated with these changes. These results provide important information for future regulations of flavoured e-cigarette products.

Assessment of inhalation toxicity of cigarette smoke and aerosols from flavor mixtures: 5-week study in A/J mice

Most flavors used in e-liquids are generally recognized as safe for oral consumption, but their potential effects when inhaled are not well characterized. In vivo inhalation studies of flavor ingredients in e-liquids are scarce. A structure-based grouping approach was used to select 38 flavor group representatives (FGR) on the basis of known and in silico-predicted toxicological data. These FGRs were combined to create prototype e-liquid formulations and tested against cigarette smoke (CS) in a 5-week inhalation study. Female A/J mice were whole-body exposed for 6 h/day, 5 days/week, for 5 weeks to air, mainstream CS, or aerosols from (1) test formulations containing propylene glycol (PG), vegetable glycerol (VG), nicotine (N; 2% w/w), and flavor (F) mixtures at low (4.6% w/w), medium (9.3% w/w), or high (18.6% w/w) concentration or (2) base formulation (PG/VG/N). Male A/J mice were exposed to air, PG/VG/N, or PG/VG/N/F-high under the same exposure regimen. There were no significant mortality or in-life clinical findings in the treatment groups, with only transient weight loss during the early exposure adaptation period. While exposure to flavor aerosols did not cause notable lung inflammation, it caused only minimal adaptive changes in the larynx and nasal epithelia. In contrast, exposure to CS resulted in lung inflammation and moderate-to-severe changes in the epithelia of the nose, larynx, and trachea. In summary, the study evaluates an approach for assessing the inhalation toxicity potential of flavor mixtures, thereby informing the selection of flavor exposure concentrations (up to 18.6%) for a future chronic inhalation study.

Insight into the pulmonary molecular toxicity of heated tobacco products using human bronchial and alveolar mucosa models at air-liquid interface

Heated tobacco products (HTP) are novel nicotine delivery products with limited toxicological data. HTP uses heating instead of combustion to generate aerosol (HTP-smoke). Physiologically relevant human bronchial and alveolar lung mucosa models developed at air-liquid interface were exposed to HTP-smoke to assess broad toxicological response (n = 6-7; ISO puffing regimen; compared to sham; non-parametric statistical analysis; significance: p < 0.05). Elevated levels of total cellular reactive oxygen species, stress responsive nuclear factor kappa-B, and DNA damage markers [8-hydroxy-2'-deoxyguanosine, phosphorylated histone H2AX, cleaved poly-(ADP-Ribose) polymerase] were detected in HTP-smoke exposed bronchial and/or alveolar models. RNA sequencing detected differential regulation of 724 genes in the bronchial- and 121 genes in the alveolar model following HTP-smoke exposure (cut off: p ≤ 0.01; fold change: ≥ 2). Common enriched pathways included estrogen biosynthesis, ferroptosis, superoxide radical degradation, xenobiotics, and α-tocopherol degradation. Secreted levels of interleukin (IL)1ꞵ and IL8 increased in the bronchial model whereas in the alveolar model, interferon-γ and IL4 increased and IL13 decreased following HTP-smoke exposure. Increased lipid peroxidation was detected in HTP-smoke exposed bronchial and alveolar models which was inhibited by ferrostatin-1. The findings form a basis to perform independent risk assessment studies on different flavours of HTP using different puffing topography and corresponding chemical characterization.

E-Cigarettes Reexamined: Product Toxicity

The introduction of e-cigarettes, or electronic nicotine delivery systems (ENDS), has been accompanied by controversy regarding their safety and effectiveness as a cessation aid and by an explosion in their use by youth. Their use does not involve the combustion of tobacco and the creation of harmful combustion products; they have been seen as a "harm reduction" tool that may be of assistance in promoting smoking cessation. Recognition that ENDS can deliver an array of chemicals and materials with known adverse consequences has spurred more careful examination of these products. Nicotine, nitrosamines, carbonyl compounds, heavy metals, free radicals, reactive oxygen species, particulate matter, and "emerging chemicals of concern" are among the constituents of the heated chemical aerosol that is inhaled when ENDS are used. They raise concerns for cardiovascular and respiratory health that merit the attention of clinicians and regulatory agencies. Frequently cited concerns include evidence of disordered respiratory function, altered hemodynamics, endothelial dysfunction, vascular reactivity, and enhanced thrombogenesis. The absence of evidence of the consequences of their long-term use is of additional concern. Their effectiveness as cessation aids and beneficial impact on health outcomes continue to be examined. It is important to ensure that their production and availability are thoughtfully regulated to optimise their safety and permit their use as harm reduction devices and potentially as smoking-cessation aids. It is equally vital to effectively prevent them from becoming ubiquitous consumer products with the potential to rapidly induce nicotine addiction among large numbers of youth. Clinicians should understand the nature of these products and the implications of their use.

Nose-Only Exposure to Cherry- and Tobacco-Flavored E-Cigarettes Induced Lung Inflammation in Mice in a Sex-Dependent Manner

Flavoring chemicals in electronic nicotine delivery systems have been shown to cause cellular inflammation; meanwhile, the effects of fruit and tobacco flavors on lung inflammation by nose-only exposures to mice are relatively unknown. We hypothesized that exposure to flavored e-cigarettes would cause lung inflammation in C57BL/6 J mice. The mice were exposed to air, propylene glycol/vegetable glycerin, and flavored e-liquids: Apple, Cherry, Strawberry, Wintergreen, and Smooth & Mild Tobacco, one hour per day for three days. Quantification of flavoring chemicals by proton nuclear magnetic resonance spectroscopy (1H NMR), differential cell counts by flow cytometry, pro-inflammatory cytokines/chemokines by ELISA, and matrix metalloproteinase levels by western blot were performed. Exposure to PG/VG increased neutrophil cell count in lung bronchoalveolar lavage fluid (BALF). KC and IL6 levels were increased by PG/VG exposure and female mice exposed to Cherry flavored e-cigarettes, in lung homogenate. Mice exposed to PG/VG, Apple, Cherry, and Wintergreen increased MMP2 levels. Our results revealed flavor- and sex-based e-cigarette effects in female mice exposed to cherry-flavored e-liquids and male mice exposed to tobacco-flavored e-liquids, namely, increased lung inflammation.

E-cigarette aerosol exacerbates cardiovascular oxidative stress in mice with an inactive aldehyde dehydrogenase 2 enzyme

Background

E-cigarette aerosol containing aldehydes, including acetaldehyde, are metabolized by the enzyme aldehyde dehydrogenase 2 (ALDH2). However, little is known how aldehyde exposure from e-cigarettes, when coupled with an inactivating ALDH2 genetic variant, ALDH2*2 (present in 8% of the world population), affects cardiovascular oxidative stress.

Objectives

The study was to determine how e-cigarette aerosol exposure, coupled with genetics, impacts cardiovascular oxidative stress in wild type ALDH2 and ALDH2*2 knock-in mice.

Methods

Using selective ion flow mass spectrometry, we determined e-cigarette aerosol contains acetaldehyde levels 10-fold higher than formaldehyde or acrolein. Based on this finding, we tested how isolated ALDH2*2 primary cardiomyocytes respond to acetaldehyde and how intact ALDH2*2 knock-in rodents instrumented with telemeters respond physiologically and at the molecular level to 10 days of e-cigarette aerosol exposure relative to wild type ALDH2 rodents.

Results

For ALDH2*2 isolated cardiomyocytes, acetaldehyde (1 μM) caused a 4-fold greater peak calcium influx, 2-fold increase in ROS production and 2-fold increase in 4-HNE-induced protein adducts relative to wild-type ALDH2 cardiomyocytes. The heart rate in ALDH2*2 mice increased ∼200 beats/min, while, heart rate in ALDH2 mice increased ∼150 beats/min after 10 days of e-cigarette exposure, relative to air-exposed mice. E-cigarette aerosol exposure triggered ∼1.3 to 2-fold higher level of protein carbonylation, lipid peroxidation, and phosphorylation of NF-κB for both strains of mice, with this response exacerbated for ALDH2*2 mice.

Conclusions

Our findings indicate people carrying an ALDH2*2 genetic variant may be more susceptible to increases in cardiovascular oxidative stress from e-cigarette aerosol exposure.

•

~540 million people have a genetic variant in aldehyde dehydrogenase 2 (ALDH2*2) that limits aldehyde metabolism.

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Little is known how e-cigarette exposure, when coupled with the ALDH2*2 variant, impacts cardiovascular oxidative stress.

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ALDH2*2 cardiomyocytes and rodents vs. wild type have higher oxidative stress levels after aldehyde or e-cigarette exposure.

•

People with an ALDH2*2 variant may be more susceptible to cardiovascular oxidative stress from e-cigarette exposure.

Predictors of electronic cigarette use and its association with respiratory health and obesity in young adulthood in Sweden; findings from the population-based birth cohort BAMSE

Despite the growing popularity of electronic cigarettes (e-cigarettes) over the last decade, few epidemiological studies have examined the influence on respiratory health in young adulthood. The aim of this study was to identify factors associated with e-cigarette use in young adulthood in Sweden, and to examine associations between e-cigarette use and lung function, respiratory symptoms, and obesity. This cross-sectional study included 3055 young adults from Sweden and used questionnaire and clinical data obtained at age 22-25 years. The prevalence of current e-cigarette use was 3.9% (n = 120). Few participants reported daily (0.4%) or exclusive (0.8%) use of e-cigarettes. In a multivariable adjusted logistic regression model, e-cigarette use was significantly associated with male gender (OR:3.2; 95% CI:1.5-6.7) and cigarette smoking (OR:14.7; 95% CI:5.5-39.0 for daily smoking). Prevalence of cough (15.0% vs. 8.5%) and mucus production (22.3% vs. 14.8%) was significantly higher among e-cigarette users compared to non-users, while no difference in lung function was observed. In addition, the prevalence of overweight/obesity was higher among e-cigarette users compared to non-users (36.7% vs. 22.3% with BMI≥25 kg/m²). In conclusion, cigarette smokers and males used e-cigarette more often compared to females and non-cigarette smokers. Attention should be given to respiratory symptoms among e-cigarette users, although our results may be explained by the concurrent use of conventional cigarettes, as the group of exclusive e-cigarette users were too small to allow firm conclusions.

Toxicological Assessment of Flavor Ingredients in E-Vapor Products

Many flavor ingredients are often used in potentially reduced-risk tobacco products (such as e-vapor products). Although most are “generally recognized as safe (GRAS)” when used in food, there is limited information available on their long-term health effects when delivered by inhalation. While obtaining route-of-exposure-specific toxicological data on flavor ingredients is critical to product evaluation, the large number of individual flavor ingredients available and their potential combinations render classical toxicological assessment approaches impractical, as they may require years of preclinical investigations and thousands of laboratory animals. Therefore, we propose a pragmatic approach in which flavor ingredients are initially assigned to groups of structurally related compounds (Flavor Groups), from which flavor group representatives (FGR) are then selected and tested individually and as a mixture in vitro and in vivo. The premise is that structurally related compounds would have comparable metabolic and biological activity and that the data generated using FGRs could support the toxicological assessment of other structurally related flavor ingredients of their respective Flavor Groups. This approach is explained in a step-wise manner and exemplified by a case study, along with its strengths, limitations as well as recommendations for further confirmatory testing. Once completed, this FGR approach could significantly reduce the time and resources required for filling the data gap in understanding the health risks of many flavor ingredients while also minimizing the need for laboratory animals.

Differential impact of JUUL flavors on pulmonary immune modulation and oxidative stress responses in male and female mice

JUUL is a popular e-cigarette brand that manufactures e-liquids in a variety of flavors, such as mango and mint. Despite their popularity, the pulmonary effects of flavored JUUL e-liquids that are aerosolized and subsequently inhaled are not known. Therefore, the purpose of this study was to evaluate if acute exposure to JUUL e-cigarette aerosols in three popular flavors elicits an immunomodulatory or oxidative stress response in mice. We first developed a preclinical model that mimics human use patterns of e-cigarettes using 1 puff/min or 4 puffs/min exposure regimes. Based on cotinine levels, these exposures were representative of light/occasional and moderate JUUL users. We then exposed C57BL/6 mice to JUUL e-cigarette aerosols in mango, mint, and Virginia tobacco flavors containing 5% nicotine for 3 days, and assessed the inflammatory and oxidative stress response in the lungs and blood. In response to the 1 puff/min regime (light/occasional user), there were minimal changes in BAL cell composition or lung mRNA expression. However, at 4 puffs/min (moderate user), mint-flavored JUUL significantly increased lung neutrophils, while mango-flavored JUUL significantly increased Tnfα and Il13 mRNA in the lungs. Both the 1- and 4 puffs/min regimes significantly increased oxidative stress markers in the blood, indicating systemic effects. Thus, JUUL products are not inert; even short-term inhalation of flavored JUUL e-cigarette aerosols differentially causes immune modulation and oxidative stress responses.

E-Liquids from Seven European Countries–Warnings Analysis and Freebase Nicotine Content

Electronic cigarettes are available in a variety of devices with e-liquids also available in many flavors, and nicotine concentrations, albeit less than 20 mg/mL in Europe. Given the dynamics of these products, it is important to evaluate product content, including labeling, nicotine content versus labeled claim, nicotine form, and other aspects that may help policy decisions and align with the Tobacco Product Directive (TPD). Herein, we performed a study on 86 e-liquids from seven European countries (Croatia, Czech Republic, France, Germany, Italy, Poland, and the United Kingdom) with 34 different liquid brands and 57 different flavors. Nicotine content versus labeled claim, labeling, volume, pH, and nicotine form (i.e., freebase nicotine) were evaluated. From all tested products, eight of them from Germany, Poland, and UK (from 3 to 18 mg/mL), met the ±2% criteria. The ±10% criteria was fulfilled by 50 (58.1%) liquids from all countries. Among 71 liquids which contained nicotine, (one e-liquid labeled as 6 mg/mL had no nicotine level quantified), the amount of freebase nicotine differed from 0 to 97.8%, with a mean value 56.5 ± 35.7. None of the tested liquids had nicotine salt listed in the ingredients. Therefore, a low level of freebase nicotine in some liquids was most likely achieved by added flavorings. All tested liquids presented in this study met the basic requirements of the TPD. There were differences in the scope of information about harmfulness, type of warnings on packaging, attaching leaflets, placing graphic symbols, and discrepancies between the declared and quantified nicotine concentrations.

Flavor components in tobacco capsules identified through non-targeted quantitative analysis

Tobacco flavors increase the attractiveness of a tobacco brand and ultimately promote addiction. Information about what flavor and how much flavor is in flavor capsules can provide an effective way to regulate tobacco flavor. In this study, 128 flavor chemicals were identified and quantified by gas chromatography-mass spectrometry using libraries and authentic standards. Validation of the developed method was performed for interference, detection limits, calibration curves, accuracy, and precision. Menthol was the main ingredient in all capsules, and the carcinogenic pulegone was detected. Detected menthofuran, benzyl alcohol, geraniol, and eugenol cause toxic or severe irritation, and detected lactones can increase nicotine addiction by inhibiting nicotine metabolism in smokers. Margin of exposures for carcinogenic pulegone and non-carcinogenic menthol were well below safety thresholds, indicating a significant risk of inhalation exposure. It is desirable to prohibit the use of flavor capsules in consideration of human risk.

Qualitative and quantitative comparison of flavor chemicals in tobacco heating products, traditional tobacco products and flavoring capsules

A gas chromatography-mass spectrometric (GC-MS) method was developed for the qualitative and quantitative analysis of flavor chemicals in tobacco heating products (THPs), traditional tobacco products (TTPs) and their flavoring capsules. A total of 283 compounds were identified through non-target analysis, and the final 302 compounds were selected to develop an analytical method. The lower limits of detection (LOD) of analytes were 0.00074-12 mg/kg and their LOD range was wide depending on the presence or absence in the reference cigarette. The precision of the 302 compounds was less than 24.5%, and the accuracy ranged from 80.0% to 120%. A total of 190 flavors and 5 contaminants were determined in 21 THP, 10 TTP, 8 THP capsules and 11 TTP capsules. When comparing the total flavor content of flavors per cigarette, it was in the order of THP capsule> TTP capsule ≫ THP ≫ TTP. The correlations between the 53 cigarette products and 190 flavor chemicals were analyzed using PCA. It has been demonstrated that PCA results can be a useful tool in differentiating brands and manufacturers of tobacco products.

COVID or Not COVID? A Great Mimicker Behind the Smoke Screen

Vaping is becoming increasingly popular as an alternative to cigarettes. However, vaping does not come without risks; electronic cigarette (e-cigarette) and vaping-associated lung injury (EVALI) is one of the most severe consequences. Coronavirus disease 2019 (COVID-19) and bacterial pneumonia cases often present with almost identical features. We present a case of a young man who presented with pneumonia that was initially thought to be related to COVID-19 infection but later diagnosed as EVALI. Clinicians should have a high suspicion of EVALI in patients who present with hypoxemia and negative infectious workup, particularly during the COVID-19 era. Administration of corticosteroids has shown remarkable efficacy in improving hypoxemia; however, many patients may have chronic lung injury and may require oxygen long-term. Cases of EVALI should continue to be reported and followed up long term for monitoring disease outcomes.

Use of heated tobacco products by people with chronic diseases: The 2019 JASTIS study

Heated tobacco products (HTPs) have become popular recently. People with chronic disease, such as diabetes, cardiovascular disease (CVD), chronic obstructive pulmonary disease (COPD) and cancer, should quit smoking for treatment and recurrence of tobacco-related diseases. However, they have difficulty in quitting smoking, and they may start HTPs use to quit smoking. The purpose of this study is to examine the use of HTPs in people with chronic disease. We used data from an internet study, the Japan Society and New Tobacco Internet Survey (JASTIS). We analyzed 9,008 respondents aged 15-73 years in 2019 using logistic regression. Current use of tobacco products was defined as use within the previous 30 days. Prevalence of current HTP use including dual use and dual use with cigarettes was 9.0% and 6.1% respectively in total. By disease: hypertension 10.2% and 7.4%, diabetes 15.9% and 12.3%, CVD 19.2% and 15.7%, COPD 40.5% and 33.3%, and cancer 17.5% and 11.9%. Diabetes, CVD, COPD, and cancer were positively associated with current use of HTPs (odds ratios (ORs) and 95% confidence intervals (CIs): 1.48 (1.06, 2.07), 2.29 (1.38, 3.80), 3.97(1.73, 9.11), and 3.58(1.99, 6.44), respectively) and dual use of cigarettes and HTPs (ORs and 95% CIs: 2.23 (1.61, 3.09), 3.58 (2.29, 5.60), 7.46 (3.76, 14.80), and 2.57 (1.46, 4.55), respectively) after adjusting for confounders. People with chronic disease were more likely to use HTPs and HTPs together with cigarettes. Further research on the smoking situation of HTPs in patients with chronic diseases is necessary.

Comparative Reactive Oxygen Species (ROS) Content among Various Flavored Disposable Vape Bars, including Cool (Iced) Flavored Bars

Studies have shown that aerosols generated from flavored e-cigarettes contain Reactive Oxygen Species (ROS), promoting oxidative stress-induced damage within pulmonary cells. Our lab investigated the ROS content of e-cigarette vapor generated from disposable flavored e-cigarettes (vape bars) with and without nicotine. Specifically, we analyzed vape bars belonging to multiple flavor categories (Tobacco, Minty Fruit, Fruity, Minty/Cool (Iced), Desserts, and Drinks/Beverages) manufactured by various vendors and of different nicotine concentrations (0-6.8%). Aerosols from these vape bars were generated via a single puff aerosol generator; these aerosols were then individually bubbled through a fluorogenic solution to semi-quantify ROS generated by these bars in H2O2 equivalents. We compared the ROS levels generated by each vape bar as an indirect determinant of their potential to induce oxidative stress. Our results showed that ROS concentration (μM) within aerosols produced from these vape bars varied significantly among different flavored vape bars and identically flavored vape bars with varying nicotine concentrations. Furthermore, our results suggest that flavoring chemicals and nicotine play a differential role in generating ROS production in vape bar aerosols. Our study provides insight into the differential health effects of flavored vape bars, in particular cool (iced) flavors, and the need for their regulation.

Analysis of furans and pyridines from new generation heated tobacco product in Japan

Background

In recent years, heated tobacco products (HTPs), which are widely used in Japan, have been sold by various brands using additives such as flavors. It has been reported that the components of mainstream smoke are different from those of conventional cigarettes. In this study, we established an analytical method for furans and pyridines in the mainstream smoke, which are characteristic of HTPs and particularly harmful among the generated components, and investigated the amount of component to which the smokers are exposed.

Methods

We established a simple analytical method for simultaneous analysis of gaseous and particulate compounds in the mainstream smoke of HTPs (IQOS, glo, ploom S) in Japan by combining a sorbent cartridge and glass fiber filter (Cambridge filter pad (CFP)). Both the sorbent cartridge and CFP were extracted using 2-propanol and analyzed via GC-MS/MS to determine the concentration of furans and pyridines generated from each HTP.

Results

The results showed that the levels of target furans such as furfural, 2-furanmethanol, 2(5H)-furanone, and 5-methylfurfural tended to be higher in the mainstream smoke of glo than in standard cigarettes (3R4F). Pyridine, which is generated at a high level in 3R4F as a combustion component, and 4-ethenylpyridine (EP), which is a known marker of environmental tobacco smoke, were detected. Among these components, 2-furanmethanol and pyridine are classified as Group 2B (possibly carcinogenic to humans) by the International Agency for Research on Cancer (IARC). Therefore, it is possible that they will contribute to the health effects caused by use of HTPs.

Conclusions

Using the new collection and analytical method for furans and pyridines in the mainstream smoke of HTPs, the level of each compound to which smokers are exposed could be clarified. By comprehensively combining information on the amount of ingredients and toxicity, it will be possible to perform a more detailed calculation of the health risks of using HTPs. In addition, the components detected in this study may be the causative substances of indoor pollution through exhaled smoke and sidestream smoke; therefore, environmental research on the chemicals generated from HTPs would be warranted in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-021-01008-1.

E-cigarettes induce toxicity comparable to tobacco cigarettes in airway epithelium from patients with COPD

BACKGROUND

The health effects of e-cigarettes in patients with pre-existing lung disease are unknown. The aim of this study was to investigate whether aerosols from a fourth-generation e-cigarette produces similar in-vitro cytotoxic, DNA damage and inflammatory effects on bronchial epithelial cells (BECs) from patients with COPD, as cigarette smoke.

METHODS

BECs from patients with COPD who underwent surgery for lung cancer and comparator (immortalised 16HBE) cells were grown at air liquid interface (ALI). BECs were exposed to aerosols from a JUUL® e-cigarette (Virginia Tobacco and Menthol pods at 5% nicotine strength) or reference 3R4F cigarette for 30 min at ALI. Cell cytotoxicity, DNA damage and inflammation were measured.

RESULTS

In response to the Virginia Tobacco and Menthol flavoured e-cigarette aerosols, COPD BECs showed comparable LDH release (cell cytotoxicity, p = 0.59, p = 0.67 respectively), DNA damage (p = 0.41, p = 0.51) and inflammation (IL-8, p = 0.20, p = 0.89 and IL-6, p = 0.24, p = 0.93), to cigarette smoke. 16HBE cells also showed comparable cellular responses to cigarette smoke.

CONCLUSION

In airway cells from patients with COPD, aerosols from a fourth-generation e-cigarette were associated with similar toxicity to cigarette smoke. These results have potential implications for the safety of e-cigarette use in patients with lung disease.

Harms of Electronic Cigarettes: What the Healthcare Provider Needs to Know

Electronic cigarettes (e-cigarettes) reached the market without either extensive preclinical toxicology testing or long-term safety trials that would be required of conventional therapeutics or medical devices. E-cigarettes are considered a tobacco product and as such have no manufacturing quality or safety standards. A growing body of evidence documents severe harms from e-cigarette use, including injuries from product explosions, nicotine poisoning, and severe lung diseases. Commonly used e-cigarette components have significant inhalation toxicity. Emerging evidence from laboratory studies suggests substantial reason for concern for long-term harms, including risk for cardiovascular disease, chronic obstructive lung disease, and cancer. Rather than helping people stop smoking, e-cigarette use is associated with reduced rates of smoking cessation among current smokers and an increased risk of relapse to smoking among former smokers. The World Health Organization advises, "Unlike the tried and tested nicotine and non-nicotine pharmacotherapies that are known to help people quit tobacco use, WHO does not endorse e-cigarettes as cessation aids." Careful evaluation of all the available research justifies a strong recommendation that healthcare providers should neither prescribe nor recommend e-cigarettes for persons who are tobacco dependent. If a patient is dependent on e-cigarettes, the healthcare provider should provide counseling and treatment (of nicotine dependence) to help the patient to stop their e-cigarette use.

Clinical Pharmacology of Electronic Nicotine Delivery Systems (ENDS): Implications for Benefits and Risks in the Promotion of the Combusted Tobacco Endgame

Electronic nicotine delivery systems (ENDS) such as e-cigarettes and heated tobacco products are novel battery-operated devices that deliver nicotine without combustion of tobacco. Because cigarette smoking is sustained by nicotine addiction and the toxic combustion products are mainly responsible for the harmful effects of smoking, ENDS could be used to promote smoking cessation while exposing users to lower levels of toxicants compared with conventional cigarettes. The currently available evidence from clinical and observational studies indicates a potential role of e-cigarettes as smoking cessation aids, although many continue to use e-cigarettes long after quitting smoking. Nicotine and toxicant delivery vary considerably by device and depend on the characteristics of the e-liquid formulation. Because smokers tend to titrate their nicotine intake to maintain their desired pharmacologic effects, device and liquid characteristics need to be considered when using ENDS as an aid to quit smoking. Factors potentially limiting their use are the currently still unknown long-term safety of these products and concerns regarding widespread use among youth. Implications of clinical pharmacology data on ENDS for the cigarette endgame and regulation by the U.S. Food and Drug administration are discussed.

Biomarkers of Inflammation and Oxidative Stress among Adult Former Smoker, Current E-Cigarette Users-Results from Wave 1 PATH Study

BACKGROUND

Former smokers who currently use e-cigarettes have lower concentrations of biomarkers of tobacco toxicant exposure than current smokers. It is unclear whether tobacco toxicant exposure reductions may lead to health risk reductions.

METHODS

We compared inflammatory biomarkers (high-sensitivity C-reactive protein, IL6, fibrinogen, soluble intercellular adhesion molecule-1) and an oxidative stress marker (F2-isoprostane) among 3,712 adult participants in Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health Study by tobacco user groups: dual users of cigarettes and e-cigarettes; former smokers who currently use e-cigarettes-only; current cigarette-only smokers; former smokers who do not currently use any tobacco; and never tobacco users. We calculated geometric means (GM) and estimated adjusted GM ratios (GMR).

RESULTS

Dual users experienced greater concentration of F2-isoprostane than current cigarette-only smokers [GMR 1.09 (95% confidence interval, CI, 1.03-1.15)]. Biomarkers were similar between former smokers who currently use e-cigarettes and both former smokers who do not use any tobacco and never tobacco users, but among these groups most biomarkers were lower than those of current cigarette-only smokers. The concentration of F2-isoprostane decreased by time since smoking cessation among both exclusive e-cigarette users (P _trend = 0.03) and former smokers who do not currently use any tobacco (P _trend = 0.0001).

CONCLUSIONS

Dual users have greater concentration of F2-isoprostane than smokers. Exclusive e-cigarette users have biomarker concentrations that are similar to those of former smokers who do not currently use tobacco, and lower than those of exclusive cigarette smokers.

IMPACT

This study contributes to an understanding of the health effects of e-cigarettes.

A newly developed aerosol exposure apparatus for heated tobacco products for in vivo experiments can deliver both particles and gas phase with high recovery and depicts the time-dependent variation in nicotine metabolites in mouse urine

INTRODUCTION

There is no standardized aerosol exposure apparatus to deliver heated tobacco products (HTPs) for in vivo experiments. Therefore, we developed a novel HTPs aerosol exposure apparatus for mice and demonstrated that nicotine and other chemicals in HTPs aerosol generated by the apparatus can be delivered to mice which replicate human smoke.

METHODS

The amounts of nicotine, tar, and carbon monoxide (CO) in IQOS (Marlboro Regular HeatSticks™) aerosol generated by two types of apparatuses were determined. C57BL/6N mice were exposed to IQOS aerosol, followed by determination of the urinary nicotine metabolites. Further, the skin surface temperature of mice was monitored to confirm the vasoconstriction action of nicotine.

RESULTS

The amounts of chemicals in IQOS aerosol by the novel air push-in inhalation apparatus for HTPs (APIA) was equivalent to that of the analytical vaping machine (LM4E) [1.60 ± 0.08 (APIA) vs 1.46 ± 0.07 mg/stick (LM4E) in nicotine and 0.55 ± 0.04 (APIA) vs 0.45 ± 0.01 mg/stick (LM4E) in CO]. After mice were exposed to IQOS aerosol by APIA, the urinary nicotine metabolites levels were determined; peak values in cotinine and 3-hydroxycotinine were 6.82 μg/mg creatinine at 1 h after exposure and 32.9 μg/mg creatinine at 2 h after exposure, respectively. The skin surface temperature decreased and was lower (33.5°C ± 0.5°C) at 30 min than before exposure (37.6°C ± 0.8°C).

CONCLUSIONS

The new apparatus for HTPs aerosol exposure to mice showed good performances in terms of both chemical analysis of collected aerosol and fluctuations in the urinary nicotine metabolites.

Nicotinic α7 acetylcholine receptor (α7nAChR) in human airway smooth muscle

Diseases such as asthma are exacerbated by inflammation, cigarette smoke and even nicotine delivery devices such as e-cigarettes. However, there is currently little information on how nicotine affects airways, particularly in humans, and changes in the context of inflammation or asthma. Here, a longstanding assumption is that airway smooth muscle (ASM) that is key to bronchoconstriction has muscarinic receptors while nicotinic receptors (nAChRs) are only on airway neurons. In this study, we tested the hypothesis that human ASM expresses α7nAChR and explored its profile in inflammation and asthma using ASM of non-asthmatics vs. mild-moderate asthmatics. mRNA and western analysis showed the α7 subunit is most expressed in ASM cells and further increased in asthmatics and smokers, or by exposure to nicotine, cigarette smoke or pro-inflammatory cytokines TNFα and IL-13. In these effects, signaling pathways relevant to asthma such as NFκB, AP-1 and CREB are involved. These novel data demonstrate the expression of α7nAChR in human ASM and suggest their potential role in asthma pathophysiology in the context of nicotine exposure.

Perspectives on Epigenetics Alterations Associated with Smoking and Vaping

Epigenetic alterations, including DNA methylation, microRNA, and long noncoding RNA, play important roles in the pathogenesis of numerous respiratory health conditions and diseases. Exposure to tobacco smoking has been found to be associated with epigenetic changes in the respiratory tract. Marketed as a less harmful alternative to combustible cigarettes, electronic cigarette (e-cigarette) has rapidly gained popularity in recent years, especially among youth and young adults. Accumulative evidence from both animal and human studies has shown that e-cigarette use (vaping) is also linked to similar respiratory health conditions as observed with cigarette smoking, including wheezing, asthma, and COPD. This review aims to provide an overview of current studies on associations of smoking and vaping with epigenetic alterations in respiratory cells and provide future research directions in epigenetic studies related to vaping.

'I perceive it to be less harmful, I have no idea if it is or not:' a qualitative exploration of the harm perceptions of IQOS among adult users

BACKGROUND

Harm perceptions of tobacco and nicotine products can influence their use and could be targeted by policies to change behaviour. IQOS was introduced to the UK in 2016, and there is little independent qualitative research on IQOS harm perceptions. This study explored the perceived health harms of IQOS to users and those exposed to the emissions, what shapes these perceptions, and what participants wanted to know about the harms of IQOS.

METHODS

Qualitative interviews in London, UK, with 30 adult current and former IQOS users who currently smoked or quit smoking in the last 2 years.

RESULTS

IQOS was perceived as less harmful than smoking but not risk-free, although there was great uncertainty. Influences on harm perceptions were consolidated into six themes: (1) dominance of manufacturer claims influenced perceptions that IQOS is less harmful than smoking to users and those around them, although mistrust of the tobacco industry heightened scepticism about harms; (2) limited independent and long-term research led to uncertainty about harms, although some participants trusted IQOS would not be marketed if it were very harmful. Participants wanted more independent and long-term studies into harm; (3) appearance of HEETS (tobacco sticks) packaging conveyed reduced harm because packets were 'pretty', without graphic/specific warnings, although written warnings conveyed some harm. Participants wanted more information on HEETS packets about harms; (4) process of heating and HEETS contents-heating, compared with burning, tobacco was perceived to produce fewer harmful chemicals, while tobacco, nicotine, and chemicals in HEETS were perceived to cause some harm. Participants wanted clarification about the harms of heating tobacco and HEETS ingredients; (5) improvements in physical health and personal appearance reduced perceptions of harm; (6) differences in sensory experiences (taste, sight, smell) when using IQOS over smoking reduced perceptions of harm, while 'black' deposits inside IQOS led to perceptions of some harm. Reduced volume and smell of IQOS emissions also reduced perceptions of harm to non-users exposed to the emissions.

CONCLUSIONS

IQOS was perceived as less harmful than smoking but not risk-free, although there was great uncertainty. Participants wanted clarification about IQOS harms from independent sources in accessible forms, specifically related to HEETS ingredients, heating tobacco, and emissions to others.