Chemical hazards present in liquids and vapors of electronic cigarettes

Chemical Analysis and Flavor Distribution of Electronic Cigarettes in Australian Schools

INTRODUCTION

Adolescent usage of electronic cigarettes has increased globally. Inconsistent, or absent, labeling of nicotine and other ingredients requires chemical analysis to accurately determine the chemical composition of these products.

AIMS AND METHODS

Electronic cigarettes confiscated from public and private high school students (N = 598) were provided for analysis from three regions in New South Wales, Australia. The products were examined for brand, model, and flavor and a subset was further analyzed for chemical composition (n = 410) quantifying nicotine, synthetic cooling agents, flavoring chemicals, and prohibited ingredients by gas chromatography-mass spectrometry (GC-MS).

RESULTS

The majority of samples provided were fruit-flavored disposable e-cigarettes across three main brands (IGET, HQD, and Gunnpod). Nicotine was quantified in 97.3% of disposable samples with an average concentration of 40.0 mg/mL, while one refill e-liquid was found to contain nicotine at a low concentration. Almost all samples contained the coolant WS-23 in relatively high concentrations compared to other flavoring chemicals present. Chemicals prohibited under the TGO110 (Australian e-cigarette product standard) were identified in 3.4% of the samples which were chemically analyzed. This included the presence of ethylene glycol in moderately high concentrations (up to 13.2 mg/mL).

CONCLUSIONS

Australian students' preferences for fruity, disposable e-cigarettes were identified regardless of region with the vast majority containing high concentrations of nicotine. WS-23 was found in most disposable e-cigarettes, potentially to reduce throat irritation from nicotine and other flavoring chemicals. The inhalational safety of the samples is of concern due to health risks associated with detected prohibited compounds, particularly ethylene glycol.

IMPLICATIONS

This is the first study to quantify nicotine, coolants, and flavoring chemicals in e-cigarette products seized from Australian high school students and has significant implications for future policy development. Students appear to be almost exclusively using disposable e-cigarettes with high nicotine concentrations and predominately fruity flavors. WS-23 may potentially be added to disposable e-cigarettes to facilitate the uptake of these products by adolescents unaccustomed to the throat irritation from nicotine and intense flavors. The e-cigarette coils were found to have degraded over time, potentially affecting the composition of the aerosol and leaching of metals.

A review of analytical techniques for the determination of e-liquid and electronic cigarette aerosol composition

Since the introduction of electronic cigarettes (ECs) to the global market, the composition of e-liquids has been a controversial topic. While some consider ECs to be an effective tool for quitting smoking, their primary criticism lies in the uncertain and varied composition of e-liquids. Manufacturers create the desired formulations by mixing different ratios of humectants, flavorings, nicotine, cannabinoids, and cooling agents. However, the health effects of inhaling these compounds are still not well understood. Regular analytical control of e-liquids and aerosols is crucial to gain valuable insights into e-liquid composition, generating new compounds during aerosolization, and the potential impact on human health. This work presents an overview of the analytical techniques used for the qualitative and quantitative determination of e-liquid and aerosol compounds, including a description of the methods used for aerosol collection. Gas and liquid chromatography are the most used analytical techniques for compound determination, followed by nuclear magnetic resonance spectroscopy. Additionally, inductively coupled plasma-mass spectrometry and inductively coupled plasma-optical emission spectroscopy are the most frequently used analytical techniques for elemental determination in e-liquids and their aerosols.

High-throughput screening of acetals/ketals in edible essences via GC-Orbitrap-MS and their formation rates at room temperature

Flavors contain active aldehydes and ketones that react with glycerol and propylene glycol to form acetals and ketals. The identification of acetals and ketals is challenging due to the incomplete information in mass spectral libraries. This study examines the reaction kinetics of 36 aldehydes and ketones with propylene glycol and glycerol, and establishes a high sensitivity and throughput screening method for 185 acetals and ketals using GC-Orbitrap-MS. Formation rates of acetals and ketals at room temperature, and influencing factors like steric hindrance, boiling point, and molecular size were explored. A high-resolution mass spectrometry database was established through model reactions and 10 market-purchased edible essences were analyzed. The analysis of edible essences showed that the detected analytes closely correspond to aldehyde and ketone species prone to hydroxyl-aldehyde condensation reactions at room temperature. This method offers high sensitivity, throughput, and accuracy for rapid screening of acetals and ketals in essences.

Stability of Flavoring Chemicals in e-Cigarette Liquids: A Naturalistic Product Aging Study over 24 months

Flavoring chemicals commonly used in many consumer products, including pharmaceuticals, foods, and beverages, deteriorate over time. Flavoring chemicals are also common additives in e-cigarette liquid formulations, but their stability in vaping products has not been evaluated. Since e-cigarette liquids are exposed to varying environmental conditions during storage and use, we assessed the stabilities of 20 flavoring chemicals commonly used in vaping products, including benzaldehyde (cherry flavor), menthol (cooling flavor), and vanillin (vanilla flavor). We prepared reference e-cigarette liquids (reference solutions) containing individual flavorings and a mixed liquid with combined flavorings in a 55:45 (v/v) propylene glycol to vegetable glycerin solution. We also purchased 14 commercial e-cigarette liquids. Liquids were stored over 24 months in different temperatures (room and cold) and light exposure conditions (ambient light and dark). Gas chromatography/mass spectrometry techniques were used to measure the concentration of each flavoring chemical at the baseline and after 1, 3, 6, 12, and 24 months. We used a nontargeted approach to identify potential degradation byproducts. Using an air-liquid interface with bronchial epithelial cells and the Neutral Red assay, we also compared the cytotoxicity of selected reference solutions vaped at the baseline and after storage over 24 months. The flavorings in reference solutions stored at ambient temperature and exposed to light were the least stable. Reducing exposure to light and storing reference solutions in cold temperatures delayed the degradation of some flavorings. Tentatively identified byproducts of flavoring degradation found in unstable reference solutions suggested oxidation, hydrolysis, and condensation reactions with solvents. Despite substantial changes in the chemical composition, no significant cytotoxicity differences were detected between fresh and aged reference solutions. Our findings suggest that storing vaping products in dark places and at cold temperatures improves the stability of flavorings in e-cigarette liquids.

Vaping and Smoking Cessation

BACKGROUND

Electronic cigarettes (e-cigarettes) or vaping address a significant unmet need for traditional smokers who are endeavoring to quit this practice.

OBJECTIVES

We conducted an extensive PubMed search to review the studies involving e-cigarettes as an ostensibly healthier alternative to cigarette smoking and an approach to smoking cessation.

RESULTS

E-cigarettes are potentially carcinogenic, may confer severe cardiopulmonary symptoms and are inconclusively effective at occasioning smoking cessation; hence, consumers should be circumspect when considering this inhalation practice, especially vulnerable populations (e.g., teenagers and young adults) who may exhibit a greater proclivity to adopting this lifestyle choice.

CONCLUSIONS

Since the smoking cessation results are equivocal and the long-term safety and addictive nature of nicotine-containing e-cigarettes remain concerning, the use of e-cigarettes should be inadvisable until proven otherwise.

Disposable electronic cigarettes - chemical composition and health effects of their use. A systematic review

OBJECTIVE

Despite the rising popularity of disposable e-cigarettes, little is known about their chemical characteristics, or their impact on users' health. This work attempts to summarize current knowledge about chemical composition and known health effects of disposable e-cigarettes.

METHODS

The literature search was performed in February and March 2024 in Pub Med and Science Direct databases (no time range) by the terms 'disposable electronic cigarette', 'disposable e-cigarette', 'disposable e-cigs', 'cig-a-like e-cigarette', 'cig-a-like electronic cigarette'.

RESULTS

Disposable e-cigarettes contain: nicotine, humectants (propylene glycol, glycerin), flavoring agents (diacetyl, acetoin, triacetin, p-menthone, triethyl citrate, ethyl maltol, 3-hexen-1-ol, methyl anthranilate, α-terpineol, perillartine, benzyl alcohol, vanillin, melonal, methyl dihydrojasmonate, and γ-decalactone), cooling agents (WS-3, WS-23, menthol), carbonyl compounds (acetaldehyde, formaldehyde, propionaldehyde, acetone, acrolein) volatile organic compounds (VOCs) (benzene, ethanol, methanol, styrene, acetylpirazine and 2,3,5-trimethylpyrazine), metals and inorganic compounds (chromium, nickel, manganese, lead, aluminum, and zinc) and reactive oxygen species. Furthermore, there was some evidence of nicotine dependence, risk of cancer and adverse respiratory effects of using disposable e-cigarettes.

CONCLUSIONS

Despite the fact that disposable e-cigarettes contain significantly less toxins compared to combustible cigarettes, they include compounds that are absent in such products that may provide health risk in prolonged usage. In addition, there is a limited number of data on the health effect of disposable e-cigarettes, especially in long time period, for never-smokers. Therefore, due to growing popularity of disposable e-cigarettes among young people, who choose them when initiating nicotine use, further research on their long-term impact of on the users' health is necessary.

Multiorgan Crystal Deposition in Acute Ethylene Glycol Toxicity

ABSTRACT

Ethylene glycol (EG) is a widely available chemical and a well-known toxin in forensic pathology, which can lead to severe metabolic acidosis and death. Its metabolism in the body leads to formation of calcium oxalate (CO) crystals, which can precipitate in the kidney leading to renal failure. Although the identification of CO crystals in the kidney is widely known, the deposition of CO crystals in other organs has only occasionally been reported and seldom studied. This report examines 18 deaths due to EG toxicity for the presence of CO crystals in various organs. CO crystals were identified most often in the kidneys, followed by the brain and lungs. It is hypothesized that crystal deposition in these other organs may contribute to the toxicity of EG.

Composition of e-cigarette aerosols: A review and risk assessment of selected compounds

The potential harms and benefits of e-cigarettes, or electronic nicotine delivery systems (ENDS), have received significant attention from public health and regulatory communities. Such products may provide a reduced risk means of nicotine delivery for combustible cigarette smokers while being inappropriately appealing to nicotine naive youth. Numerous authors have examined the chemical complexity of aerosols from various open- and closed-system ENDS. This body of literature is reviewed here, with the risks of ENDS aerosol exposure among users evaluated with a margin of exposure (MoE) approach for two non-carcinogens (methylglyoxal, butyraldehyde) and a cancer risk analysis for the carcinogen N-nitrosonornicotine (NNN). We identified 96 relevant papers, including 17, 13, and 5 reporting data for methylglyoxal, butyraldehyde, and NNN, respectively. Using low-end (minimum aerosol concentration, low ENDS use) and high-end (maximum aerosol concentration, high ENDS use) assumptions, estimated doses for methylglyoxal (1.78 × 10-3-135 μg/kg-bw/day) and butyraldehyde (1.9 × 10-4-66.54 μg/kg-bw/day) corresponded to MoEs of 227-17,200,000 and 271-280,000,000, respectively, using identified points of departure (PoDs). Doses of 9.90 × 10-6-1.99 × 10-4 μg/kg-bw/day NNN corresponded to 1.4-28 surplus cancers per 100,000 ENDS users, relative to a NNN-attributable surplus of 7440 per 100,000 cigarette smokers. It was concluded that methylglyoxal and butyraldehyde in ENDS aerosols, while not innocuous, did not present a significant risk of irritant effects among ENDS users. The carcinogenic risks of NNN in ENDS aerosols were reduced, but not eliminated, relative to concentrations reported in combustible cigarette smoke.

Comparing E-Cigarettes and Traditional Cigarettes in Relation to Myocardial Infarction, Arrhythmias, and Sudden Cardiac Death: A Systematic Review and Meta-Analysis

BACKGROUND

The use of electronic cigarettes (e-cigarettes) as a perceived safer alternative to traditional cigarettes has grown rapidly. However, the cardiovascular risks associated with e-cigarettes compared to regular cigarettes remain unclear.

OBJECTIVE

To systematically review and compare the cardiovascular outcomes of e-cigarette use versus traditional cigarette use, focusing on the risks of myocardial infarction, arrhythmias, and sudden death.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Peer-reviewed studies published in English were included if they reported cardiovascular outcomes related to e-cigarette or traditional cigarette use. A total of 20 studies were included, covering observational and interventional studies focusing on heart rate variability, myocardial infarction, arrhythmias, and sudden cardiac events. The quality of the evidence was assessed using the GRADE criteria, and data were extracted and analyzed based on the PICOS (Population, Interventions, Comparisons, Outcomes, and Study designs) framework.

RESULTS

The systematic review found that both e-cigarettes and traditional cigarettes pose significant cardiovascular risks, with traditional cigarettes linked to a higher incidence of myocardial infarction, arrhythmias, and sudden cardiac death. E-cigarette users also face increased risks of arrhythmias and myocardial infarction compared to non-smokers, primarily due to the constituents of aerosolized e-liquid, including nicotine and flavorings, which contribute to adverse cardiac effects. Regular e-cigarette use, particularly in combination with traditional cigarette use, was associated with a heightened risk of myocardial infarction. Studies also reported heart function abnormalities, such as systolic and diastolic dysfunction, and reduced ejection fractions. Additionally, changes in heart rate variability, heart rate, and blood pressure were observed, indicating both acute and chronic effects of e-cigarettes on cardiovascular autonomic regulation.

CONCLUSIONS

While e-cigarettes may present a lower cardiovascular risk compared to traditional cigarettes, they are not without harm. Both products are linked to increased risks of myocardial infarction and arrhythmias, though traditional cigarettes pose a higher overall threat. Given the limitations in the current evidence base, particularly concerning the long-term effects of e-cigarette use, further research is needed to clarify these cardiovascular risks and inform public health guidelines.

E-Cigarettes induce expression of procoagulant tissue factor in cultivated human endothelial cells

BACKGROUND

E-cigarettes (ECIG) are proposed as an alternative for regular tobacco users with less dangerous effects for health. Several studies demonstrated that ECIG exert deleterious cardiovascular effects and promote platelet dependent thrombosis. However, ECIG role on Tissue Factor-dependent thrombosis is still unknown. Dysfunctional endothelial cells (ECs) are known to express Tissue Factor (TF) on their surface. Aim of the present study was to investigate whether ECIG might promote TF expression in ECs, shifting them to a pro thrombotic phenotype.

METHODS

Human Umbilical Vein Endothelial Cells (HUVEC) were incubated with increasing doses of ECIG (commercially available and mix of propylene glycol/vegetable glycerine/nicotine 18 mg/mL) up to 1.8 mg/mL. TF gene expression and protein levels were assessed at different time points by Real Time PCR and Western Blot, respectively. TF surface expression and activity were also measured by FACS analysis and coagulation assay. Finally, NF-kB translocation was investigated as possible mechanism of action. Potential protective effects by Rosuvastatin were also investigated.

RESULTS

ECIG significantly increased TF expression at both gene and protein levels in a time and dose dependent manner. Surface expression and procoagulant activity were increased as well. These phenomena appeared modulated by the NF-κB pathway. Rosuvastatin reduced ECIG effects on TF-mRNA.

CONCLUSIONS

Although in vitro, we indicate that ECIG promote a pro thrombotic phenotype in ECs via expression of functional TF. Data of the present study permit to shed a brighter light on the still partially unresolved issue about the role of ECIG in development of cardiovascular diseases suggesting that they might represent a potential risk factor for thrombotic cardiovascular events.

The biochemistry of the carcinogenic alcohol metabolite acetaldehyde

Acetaldehyde (AcH) is the first metabolite of ethanol and is proposed to be responsible for the genotoxic effects of alcohol consumption. As an electrophilic aldehyde, AcH can form multiple adducts with DNA and other biomolecules, leading to function-altering and potentially toxic and carcinogenic effects. In this review, we describe sources of AcH in humans, including AcH biosynthesis mechanisms, and outline the structures, properties and functions of AcH-derived adducts with biomolecules. We also describe human AcH detoxification mechanisms and discuss ongoing challenges in the field.

Breaking the Myths Around e-Cigarettes: A Narrative Review Exploring the Impact of e-Cigarette on Human Health

In 2006, electronic cigarettes, or e-cigarettes, made their debut on the international scene. The term Electronic Nicotine Delivery Systems (ENDS) was introduced by the World Health Organization (WHO) in 2009 to refer to the many kinds of electronic cigarettes that include nicotine. This review article will provide a full investigation of the relationship between vaping and its effects on the body. The keywords utilized for search include "smoking cessation," "smoking," "e-cigarette use in adolescents," "human health," and "e-cigarettes." Our review goes into detail on the mechanism and components that make up a vaporizer. It explains how the components cause various side effects on human health. It is illustrated that vaping has various side effects and suggested that the risk of using vape should be educated to all. e-Cigarettes should be subjected to the same marketing limitations and establish quality standards for ingredients and functioning of e-cigarette devices. Thus, by deepening our understanding of these relationships and providing the results of the analysis accompanied by concise and meaningful illustrations to aid in understanding vaping and the physiological effects of the potential harm from vaping, we pave the way for future research on the quantity of puff to determine the harm level.

Enhancing translation: A need to leverage complex preclinical models of addictive drugs to accelerate substance use treatment options

Preclinical models of addictive drugs have been developed for decades to model aspects of the clinical experience in substance use disorders (SUDs). These include passive exposure as well as volitional intake models across addictive drugs and have been utilized to also measure withdrawal symptomatology and potential neurobehavioral mechanisms underlying relapse to drug seeking or taking. There are a number of Food and Drug Administration (FDA)-approved medications for SUDs, however, many demonstrate low clinical efficacy as well as potential sex differences, and we also note gaps in the continuum of care for certain aspects of clinical experiences in individuals who use drugs. In this review, we provide a comprehensive update on both frequently utilized and novel behavioral models of addiction with a focus on translational value to the clinical experience and highlight the need for preclinical research to follow epidemiological trends in drug use patterns to stay abreast of clinical treatment needs. We then note areas in which models could be improved to enhance the medications development pipeline through efforts to enhance translation of preclinical models. Next, we describe neuroscience efforts that can be leveraged to identify novel biological mechanisms to enhance medications development efforts for SUDs, focusing specifically on advances in brain transcriptomics approaches that can provide comprehensive screening and identification of novel targets. Together, the confluence of this review demonstrates the need for careful selection of behavioral models and methodological parameters that better approximate the clinical experience combined with cutting edge neuroscience techniques to advance the medications development pipeline for SUDs.

The analysis of e-liquids: A study on chemical diversity and metal content using gas chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry

This work aimed to determine the chemical composition of 22 e-liquids available on the Slovenian market. Four different gas chromatography (GC) sample introduction techniques; headspace-GC-mass spectrometry (HS-GC-MS), liquid injection-GC-MS (LI-GC-MS), HS-solid-phase microextraction-GC-MS (HS-SPME-GC-MS), and direct-immersion-SPME-GC-MS (DI-SPME-GC-MS) were employed for qualitative analysis. Various experimental parameters were assessed for each GC sample introduction technique to maximize compound identification. Despite e-liquid packaging reporting a maximum of eight compounds, GC-MS identified more compounds in most samples, especially in menthol-flavored (58 identifiable compounds by HS-SPME-GC-MS), followed by nicotine-containing and fruit-flavored samples. HS-SPME-GC-MS identified the highest number of compounds, followed by HS-GC-MS, DI-SPME-GC-MS, and LI-GC-MS. Nicotine quantification in six samples was performed by LI-GC-MS with dilution in methanol. Nicotine concentration in samples ranged from 16.5 ± 0.5 to 18.5 ± 0.4 mg/mL, which was below the declared concentration of 20 mg/mL. Additionally, quantitative analysis of metals in e-liquids was performed by inductively coupled plasma-MS after microwave-assisted wet acid digestion. Iron was the most abundant metal, with its content ranging from 0.024 to 0.354 µg/g. Barium, bismuth, copper, and tin were also determined in several e-liquids.

Genotoxicity and mutagenicity assessment of electronic cigarette liquids

INTRODUCTION

Electronic cigarettes (e-cigarettes) are often advertised as a safer alternative to traditional smoking. However, recent data suggest they may not be as safe as previously believed. This study aims to evaluate the genotoxicity and mutagenicity of e-cigarette liquids.

METHODS

We randomly selected eight varieties of e-cigarette liquids from the local market in Jeddah, Saudi Arabia. We evaluated their genotoxicity using the Genotoxicity SOS-Chromo Test™ Kit. In this investigation, a rat liver S9 fraction was utilized to emulate liver metabolic function to measure any chemical substance's mutagenic potential. The SOS-Chromo Test was performed by recording the β-galactosidase and alkaline phosphatase activity with and without the metabolic activation enzyme (S-9).

RESULTS

All samples, except for the first two dilutions of sample 2, were nongenotoxic in the absence of the S9 activation enzyme, according to the genotoxicity analysis. However, when tested in the presence of the S9 enzyme, samples 2, 4, and 7 exhibited mutagenic activity at varying concentrations.

CONCLUSION

Contrary to common belief, e-cigarettes are not safe. The present investigation confirms the presence of both toxicants and carcinogens in some e-cigarette liquids. This exposure could increase users' risk of various health complications.

Labelling and composition of contraband electronic cigarettes: Analysis of products from Australia

BACKGROUND

The sale of nicotine-containing electronic cigarettes (e-cigarettes) is prescription only in Australia, regulated under the Standard for Nicotine Vaping Products (TGO110). Australian e-cigarette users, however, are purchasing e-cigarette products outside of the intended pathways.

METHODS

The labelling of e-cigarette packaging (N = 388 boxes) and the chemical composition of disposable e-cigarettes and pods (N = 428) were analysed for adherence to the current Australian regulations. These samples were confiscated from over-the-counter retailers in NSW by the NSW Ministry of Health during 2022 for non-compliance with Australian regulations.

RESULTS

Following the announcement of the prescription only model for nicotine-containing e-cigarettes in Australia in mid-2021 there was a clear shift in the labelling of products. Any mention of the word 'nicotine' was removed from e-cigarette packaging by early 2022 and nicotine warnings were replaced with generic underage sale warnings. Despite this labelling, the vast majority (98.8 %) of devices analysed contained nicotine, most (89 %) at high concentration (>30 mg/mL) and 4.2 % contained at least one chemical prohibited by the TGO110.

CONCLUSIONS

It appears that manufacturers have removed any mention of nicotine from the original packaging of nicotine-containing disposable e-cigarettes to circumvent restrictions on nicotine-containing products and continue their sale. The packaging of e-cigarette products in Australia is generally not indicative of their contents, particularly nicotine, and most did not display required warnings. Ingredients with associated health risks, prohibited in legal vapes by the TGO110, were found in samples. Consequently, the risks of e-cigarette use cannot be appropriately identified from the information supplied on the packaging or device.

Rates of adverse events and related risk factors following e-cigarette use

BACKGROUND

E-cigarettes have emerged as popular products, especially for younger populations. However, concerns regarding health effects exist and there is a notable gap in understanding the prevalence and nature of adverse events. This study aims to examine the rate of adverse events in individuals who use e-cigarettes in a large sample.

METHODS

A cross-sectional survey was conducted with a sample of 4695 current and former e-cigarette users with a median age of 34 years. The survey collected data on e-cigarette use, adverse events experienced, product characteristics, related behaviors, sociodemographic factors and presence of medical comorbidities. Statistical analyses were conducted using Pearson's chi-squared tests and logistic regression.

RESULTS

A total of 78.9% of respondents reported experiencing an adverse event within 6 h of using a vaping device, with the most common events being headache, anxiety and coughing. Product characteristics and related behaviors significantly influenced the risk of adverse events. There were also sociodemographic disparities, with Hispanic respondents and those with at least college-level education reporting higher rates of adverse events.

CONCLUSIONS

Our study found a high rate of adverse events among e-cigarette users. We identified that certain e-cigarette product characteristics, behaviors and medical comorbidities significantly increased the risk of these events.

Development of a Flavor Ingredient Wheel Linking E-Liquid Additives to the Labeled Flavor of Vaping Products

E-liquids contain combinations of chemicals, with many enhancing the sensory attractiveness of the product. Studies are needed to understand and characterize e-liquid ingredients, particularly flavorings, to inform future research and regulations of these products. We identified common flavor ingredients in a convenience sample of commercial e-liquids using gas chromatography-mass spectrometry. E-liquid flavors were categorized by flavor descriptors provided on the product packaging. A Flavor Ingredient Wheel was developed to link e-liquid flavor ingredients with flavor categories. An analysis of 109 samples identified 48 flavor ingredients. Consistency between the labeled flavor and ingredients used to produce such flavor was found. Our novel Flavor Ingredient Wheel organizes e-liquids by flavor and ingredients, enabling efficient analysis of the link between ingredients and their flavor profiles and allowing for quick assessment of an e-liquid ingredient's flavor profile. Investigating ingredient profiles and identifying and classifying commonly used chemicals in e-liquids may assist with future studies and improve the ability to regulate these products.

Impact of Electronic Cigarette use on Cardiovascular Health: Current Evidence, Causal Pathways, and Public Health Implications

Electronic cigarette (e-cigarette) use is increasing in Europe and the USA. While mounting evidence exists regarding an array of associated adverse health effects, to date limited evidence exists regarding the health effects of e-cigarette use on cardiovascular (CV) disease (CVD). The present review summarizes the effects of e-cigarette use on CV health. A search strategy of in vivo experimental, observational studies (including population-based cohort studies), and interventional studies was conducted in PubMed, MEDLINE, and Web of Science (April 1, 2009-April 1, 2022). The main findings revealed that the influence of e-cigarette on health are attributed mainly to the individual and interactive effects of flavors and additives used in e-cigarette fluids, along with the extended heating. The above collectively stimulate prolonged sympathoexcitatory CV autonomic effects, such as increased heart rate and diastolic blood pressure (BP), as well as decreased oxygen saturation. Hence, e-cigarette users are at increased risk of developing atherosclerosis, hypertension, arrhythmia, myocardial infarction, and heart failure. Such risks are anticipated to increase, especially among the young who are increasingly adopting e-cigarette use particularly with flavored additives. Further investigations are urgently needed to evaluate the long-term effects of e-cigarette use, particularly among susceptible population groups such as youth.

Novel chemical contaminants associated with thirdhand smoke in settled house dust

Thirdhand smoke (THS) is the persistent and toxic residue from tobacco smoke in indoor environments. A comprehensive understanding of the chemical constituents of THS is necessary to assess the risks of long-term exposure and to establish reliable THS tracers. The objective of this study was to investigate compounds associated with THS through nontargeted analysis (NTA) of settled house dust samples from smokers' and non-smokers' homes, using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS). Compounds that were either only present in dust from smokers' homes or that had significantly larger abundance than in non-smokers' homes were termed qualified compounds. We identified 140 qualified compounds, and of these, 42 compounds were tentatively identified by searching matching mass spectra in NIST electron impact (EI) mass spectral library including 20 compounds confirmed with their authentic standards. Among the 42 compounds, 26 compounds were statistically more abundant (p < 0.10) in dust from homes of smokers; seven were tobacco-specific compounds, two of which (nornicotyrine, 3-ethenylpyridine) have not been reported before in house dust. Two compounds, tris (2-chloroethyl) phosphate (a toxic compound used as a flame retardant and reported in tobacco) and propanoic acid, 2-methyl-, 1-(1,1-dimethylethyl)-2-methyl-1,3-propanediyl ester (highly abundant and reported in exhaled air of smokers), were found in dust from all smokers' homes and in zero non-smokers' homes, making these potential THS tracers, possibly associated with recent smoking. Benzyl methyl ketone was significantly higher in dust in smokers' homes, and was previously reported not as a product of tobacco but rather as a form of methamphetamine. This compound was recently reported in mainstream tobacco smoke condensate through NTA as well. These identified potential tracers and chemical components of THS in this study can be further investigated for use in developing THS contamination and exposure assessments.

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.

Safety and efficacy of e-cigarettes in those with atherosclerotic disease: a review

Smoking cessation is the most effective intervention to reduce mortality in patients with established atherosclerotic cardiovascular disease (ASCVD), with 'e-cigarettes' becoming an increasingly used intervention to achieve smoking cessation. The current review aims to summarise the current evidence base for their efficacy and safety in the ASCVD cohort. A search of the PUBMED and MEDLINE databases using the terms 'e-cigarette', 'cessation', 'safety' and 'efficacy' since 2012 yielded 706 results. Both observational and experimental studies were included, while those with an unavailable full text, non-English or duplicates were excluded, yielding 78 relevant articles, with 13 subsequent additional articles included from a search of reference lists, for a total of 91 included papers. E-cigarette vapour contains many known pro-atherosclerotic substances and has been demonstrated to potentiate traditional atherosclerotic mechanisms. While e-cigarettes may be more effective in promoting smoking cessation in the general population over a medium term (>6 months), when compared with nicotine replacement therapy (NRT), few studies specifically examined those with ASCVD, despite the latter having a higher baseline quit rate (52% vs 2%). Most studies compare e-cigarettes with NRT alone and do not include pharmacotherapy, which may be more effective in the ASCVD cohort. The single randomised controlled trial addressing the research question favoured traditional methods. Those that successfully quit smoking using e-cigarettes are more likely to continue to use the intervention at 1 year (90% vs 9%). Conflicting advice exists regarding the utilisation of e-cigarettes for smoking cessation. E-cigarettes may be inferior to standard care for smoking cessation in those with ASCVD, and their use is likely to promote the key drivers of the atherosclerotic process already active in this cohort.

Association between e-cigarette use and myocardial infarction: a systematic review and meta-analysis

BACKGROUND

The popularity of e-cigarettes has risen dramatically over the last few years, particularly among the younger population. Although the use of combustible cigarettes has established evidence to be associated with the development of several adverse cardiopulmonary diseases, the investigations regarding the prospective long-term effects of e-cigarette use on the cardiovascular system have just begun. We set to investigate if there is an association between the history of MI and e-cigarette use among smokers and non-smokers?

METHODS

The current review aims to assess the association of myocardial infarction with e-cigarette consumption. PubMed, Google Scholar, and Cochrane Central Register of Controlled Trials (CENTRAL) were queried up to October 2022 to identify articles assessing the incidence of myocardial infarction among e-cigarette users. Data were meta-analyzed using a random-effects model to derive odds ratios (OR) and 95% confidence intervals.

RESULTS

Nine studies involving 984,764 patients were included. The mean age of e-cigarette smokers was less than the controls, and female participants dominated the sample size. E-cigarette users were associated with increased odds of MI than non-users [OR = 1.44; 95% CI (1.22, 1.74); P < 0.0001]. Dual users were also associated with increased odds of MI with large effect when compared to non-users [OR = 4.04; 95% CI (3.40, 4.81); P < 0.00001].

CONCLUSIONS

Dual use is associated with an increased risk of MI than e-cigarette use only. Similarly, dual and solely e-cigarette consumption patterns of nicotine delivery are at a higher risk of MI than non-smokers.

Knowledge and Attitudes Toward E-cigarette Use: A Cross-Sectional Study From Saudi Arabia

Background In light of the fact that electronic cigarette (e-cigarette) use is a newly emerging behavior in the Middle Eastern region, where tobacco consumption is widespread, it is imperative to examine the present state of e-cigarette awareness and attitudes toward e-cigarettes. The aim of this research is to investigate the level of knowledge and attitudes pertaining to the utilization of e-cigarettes within the context of Saudi Arabia. Methodology A cross-sectional online survey study was conducted between May and September 2023 to assess public knowledge and attitudes toward e-cigarettes in Saudi Arabia. This study utilized a previously validated questionnaire to assess the knowledge and attitudes of participants regarding e-cigarettes. Binary logistic regression analysis was used to identify predictors of being knowledgeable of and having a positive attitude toward e-cigarettes. Results A total of 422 participants were involved in this study. Around one-third of the study participants were current smokers (37.2%). The median knowledge score for the study participants was 13.00 (11.00-14.00), which reflects a high level of e-cigarette knowledge. The median knowledge score for the study participants ranged between 3.00 and 15.00. The median attitude score for the study participants was 3.00 (1.00-5.00), which reflects a negative attitude toward the use of e-cigarettes. The median attitude score for the study participants ranged between 0.00 and 12.00. Participants with a monthly income of 5,001 SAR and above were more likely to be knowledgeable about e-cigarette use (p < 0.05). However, binary logistic regression analysis did not identify any statistically significant predictor of positive attitude toward the use of e-cigarettes (p > 0.05). Conclusions The study population exhibited a significant level of knowledge regarding e-cigarettes, which was coupled with a prevailing negative attitude toward their use. The income level of individuals emerged as a significant predictor of e-cigarette knowledge. To obtain a comprehensive knowledge of the factors that contribute to negative attitudes toward e-cigarette usage, particularly among specific demographic groups, it is imperative to employ a qualitative research methodology.

Oral nicotine pouches with an aftertaste? Part 2: in vitro toxicity in human gingival fibroblasts

Nicotine pouches contain fewer characteristic toxicants than conventional tobacco products. However, the associated risks in terms of toxicity and addiction potential are still unclear. Therefore, endpoints of toxicity and contents of flavoring substances were investigated in this study. The in vitro toxicity of five different nicotine pouches and the reference snus CRP1.1 were studied in human gingival fibroblasts (HGF-1). Cells were exposed to product extracts (nicotine contents: 0.03-1.34 mg/mL) and sampled at different time points. Cytotoxicity, total cellular reactive oxygen species (ROS) levels, and changes in the expression levels of inflammatory and oxidative stress genes were assessed. Flavor compounds used in the nicotine pouches were identified by GC-MS. Cytotoxicity was observed in two nicotine pouches. Gene expression of interleukin 6 (IL6) and heme oxygenase 1 (HMOX1) was upregulated by one and three pouches, respectively. ROS production was either increased or decreased, by one pouch each. CRP1.1 caused an upregulation of IL6 and elevated ROS production. Toxicity was not directly dependent on nicotine concentration and osmolarity. A total of 56 flavorings were detected in the five nicotine pouches. Seven flavorings were classified according to the harmonized hazard classification system as laid down in the European Classification, Labelling and Packaging regulation. Nine flavorings are known cytotoxins. Cytotoxicity, inflammation, and oxidative stress responses indicate that adverse effects such as local lesions in the buccal mucosa may occur after chronic product use. In conclusion, flavorings used in nicotine pouches likely contribute to the toxicity of nicotine pouches.

Electronic nicotine delivery systems (ENDS): A convenient means of smoking?

Electronic nicotine delivery systems (ENDS), which are becoming increasingly popular in many parts of the world, have recently become more sophisticated in terms of their more active content and better controlled vaporisation. This review begins by describing how cigarette smoking led to the development of ENDS as a means of combatting nicotine addiction. ENDS are usually categorised as belonging to one of only three main generations, but a fourth has been added in order to differentiate the latest, most powerful, most advanced and innovative that have improved heating efficiency. Descriptions of the principal substances contained in ENDS are followed by considerations concerning the risk of toxicity due to the presence of albeit low concentrations of such a variety of compounds inhaled over a long time, and the increasingly widespread use of ENDS as a means of smoking illicit drugs. We also review the most widely used pharmacotherapeutic approaches to smoking cessation, and recent epidemiological data showing that ENDS can help some people to stop smoking. However, in order to ensure their appropriate regulation, there is a need for higher-quality evidence concerning the health effects and safety of ENDS, and their effectiveness in discouraging tobacco smoking.

Oral nicotine pouches with an aftertaste? Part 1: screening and initial toxicological assessment of flavorings and other ingredients

Nicotine pouches are oral products that deliver nicotine without containing tobacco. Previous studies mainly focused on the determination of known tobacco toxicants, while yet no untargeted analysis has been published on unknown constituents, possibly contributing to toxicity. Furthermore, additives might enhance product attractiveness. We therefore performed an aroma screening with 48 different nicotine-containing and two nicotine-free pouches using gas chromatography coupled to mass spectrometry, following acidic and basic liquid-liquid extraction. For toxicological assessment of identified substances, European and international classifications for chemical and food safety were consulted. Further, ingredients listed on product packages were counted and grouped by function. Most abundant ingredients comprised sweeteners, aroma substances, humectants, fillers, and acidity regulators. 186 substances were identified. For some substances, acceptable daily intake limits set by European Food Safety Agency (EFSA) and Joint FAO/WHO Expert Committee on Food Additives are likely exceeded by moderate pouch consumption. Eight hazardous substances are classified according to the European CLP regulation. Thirteen substances were not authorized as food flavorings by EFSA, among them impurities such as myosmine and ledol. Three substances were classified by International Agency for Research on Cancer as possibly carcinogenic to humans. The two nicotine-free pouches contain pharmacologically active ingredients such as ashwagandha extract and caffeine. The presence of potentially harmful substances may point to the need for regulation of additives in nicotine-containing and nicotine-free pouches that could be based on provisions for food additives. For sure, additives may not pretend positive health effects in case the product is used.

Chemical analysis of electronic cigarette liquids (e-liquids) and direct nicotine quantitation using surface-assisted flowing atmospheric-pressure afterglow desorption/ionization mass spectrometry (SA-FAPA-MS)

Ambient desorption/ionization mass spectrometry (ADI-MS) has been widely used for direct analysis of real samples without sample preparation or separation. Studies on the quantification of low molecular weight compounds in complex matrices with ADI-MS remain scarce. In this paper, we report the application of surface-assisted flowing atmospheric-pressure afterglow mass spectrometry (SA-FAPA-MS) for fast qualitative screening of electronic cigarette liquid (e-liquids) ingredients and direct quantification of nicotine. The quantification approach is rapid, uses a deuterated D4-nicotine standard spike, and does not require a preceding chromatography step or other methods to remove the complex sample matrix. Selected e-liquids were directly applied on thin-layer chromatography (TLC) plate surfaces (normal phase (NP) silica, reversed phase (RP) modified silica, cyano (CN) modified silica, and dimethyl (RP2) modified silica) after dilution and internal standard spiking. The plates served purely as sample carriers and no analyte separation was performed. Promising qualitative results were obtained, demonstrating the ability to detect nicotine alkaloids using this approach and the ability to differentiate e-liquids based on their flavor variations. In addition, dimethyl- (RP2-) and cyano-modified (CN-) silica surfaces were selected for quantification based on performance results of previous studies. It was shown that results were in high accordance with high-performance liquid chromatography (HPLC) experiments with lowest deviations <3% on dimethyl surfaces. Additional quantitative experiments including a certified reference material achieved equally satisfying results with lowest deviations of -1.1% from the certified nicotine content. For nicotine, detection limits down to the fmol range (96 fmol on CN and 20 fmol on RP2) were obtained. A detailed comparison of glass surfaces with functionalized surfaces showed that the functionalized surfaces were superior in terms of sample application reproducibility, mass spectra quality, sensitivity, and information density. Thus, functionalized thin-layer surfaces are considered promising tools for both qualitative and quantitative ADI-MS analysis of complex samples.

The impact of e-cigarette exposure on different organ systems: A review of recent evidence and future perspectives

The use of electronic cigarettes (e-cigs) is rapidly increasing worldwide and is promoted as a smoking cessation tool. The impact of traditional cigs on human health has been well-defined in both animal and human studies. In contrast, little is known about the adverse effects of e-cigs exposure on human health. This review summarizes the impact of e-cigs exposure on different organ systems based on the rapidly expanding recent evidence from experimental and human studies. A number of growing studies have shown the adverse effects of e-cigs exposure on various organ systems. The summarized data in this review indicate that while e-cigs use causes less adverse effects on different organs compared to traditional cigs, its long-term exposure may lead to serious health effects. Data on short-term organ effects are limited and there is no sufficient evidence on long-term organ effects. Moreover, the adverse effects of secondhand and third hand e-cigs vapour exposure have not been thoroughly investigated in previous studies. Although some studies demonstrated e-cigs used as a smoking cessation tool, there is a lack of strong evidence to support it. While some researchers suggested e-cigs as a safer alternative to tobacco smoking, their long-term exposure health effects remain largely unknown. Therefore, more epidemiological and prospective studies including mechanistic studies are needed to address the potential adverse health effects of e-cigs to draw a firm conclusion about their safe use. A wide variation in e-cigs products and the lack of standardized testing methods are the major barriers to evaluating the existing data. Specific regulatory guidelines for both e-cigs components and the manufacturing process may be effective to protect consumer health.

Comprehensive characterization of volatile and semi-volatile compounds in e-liquids for electronic cigarette using gas chromatography accurate mass spectrometry

The consumption of electronic cigarettes is a habit with an increasing prevalence, particularly among youths. Knowing the composition of e-liquids used in these devices represents the first step to understand the potential impact of e-smoking in the health of consumers. Herein, a non-target screening methodology was applied to the identification of volatile and semi-volatile compounds in a set of e-liquids from different suppliers, with different flavors, and containing different kinds of additives, such as nicotine or cannabidiol. To this end, samples were characterized by gas chromatography accurate mass spectrometry, using a time-of-flight mass analyzer. Combination of deconvoluted electronic ionization mass spectra with linear retention index values, obtained for two columns with different selectivity, permitted the identification of more than 250 chemicals with different confidence levels. Among them, respiratory pro-inflammatory compounds, acetals of propylene glycol and glycerin with aldehydes, nicotine-related and non-related alkaloids, and psychoactive cannabinoids were confirmed as concerning compounds in e-liquid samples. Concentration ratios between propylene glycol acetals and parent aldehydes varied in the range from 2% (ethyl vanillin) to more than 80% (case of benzaldehyde). The ratios between the concentrations of delta-9-tetrahydrocannabinol and cannabidiol in e-liquids stayed in the range from 0.02% to 0.3%.

Quantitation and Stability of Nicotine in Canadian Vaping Liquids

Electronic cigarettes (e-cigarettes, vaping products) have become increasingly popular, with recent increases in use associated with closed systems delivering higher concentrations of nicotine. Most vaping products designed as an alternative to combustible cigarettes contain nicotine. A number of published studies have examined the reported concentrations of nicotine in vaping liquids (e-liquids) and found discrepancies between labelled and measured levels. Some discrepancy can also be explained by the lack of stability of nicotine in these types of products. Recently, a chemical analysis method for the quantitative determination of low and high levels of nicotine in vaping liquids was developed. This method uses dilution with acetonitrile prior to analysis with gas chromatograph mass spectrometry (GC-MS) in single ion monitoring mode (SIM). The developed method was validated using a laboratory-prepared vaping liquid as well as commercially available, nicotine-free products fortified with nicotine in the laboratory. The method detection limit (MDL) and the limit of quantitation (LOQ) for nicotine were calculated to be 0.002 mg/mL and 0.006 mg/mL, respectively. The newly developed method was applied to quantify nicotine in commercially available vaping liquids of various flavour profiles and across a wide range of nicotine concentrations, including those with nicotine salts. Furthermore, a subset of vaping liquids were analyzed to elucidate nicotine stability in various product subtypes. After a period of six months of accelerated storage to mimic one year, the overall mean percent of the original nicotine concentration remaining in the salt-based vaping products was 85% (minimum 64%, maximum 99%) while in the free-base nicotine products it was 74% (minimum 31%, maximum 106%). Nicotine stability in vaping liquids was found to be influenced by the nicotine form (pH) of formulation and its chemical composition. Non-targeted, qualitative analysis of chemical composition of vaping products showed that most constituents were identified and found to be remaining in the products following stability trials; however, three new compounds were tentatively identified in some vaping liquids at the end of the stability trials. Stability studies and the accurate quantitation of nicotine in vaping products can help inform product standards related to the safety, quality and utility of vaping products as a smoking cessation tool.

An Overview of E-Cigarette Impact on Reproductive Health

Electronic cigarettes (e-cigarettes) are often considered a "safe substitute" for conventional cigarette cessation. The composition of the fluid is not always clearly defined and shows a large variation within brands and manufacturers. More than 80 compounds were detected in liquids and aerosols. E-cigarettes contain nicotine, and the addition of flavorings increases the toxicity of e-cigarette vapour in a significant manner. The heat generated by the e-cigarette leads to the oxidation and decomposition of its components, eventually forming harmful constituents in the inhaled vapour. The effects of these toxicants on male and female reproduction are well established in conventional cigarette smokers. Although toxins were measured at much lower levels in e-cigarette aerosols compared to smoke from a conventional cigarette, there are concerns about their potential impact on male and female reproduction. The information available was mainly obtained from studies conducted in animal models, and investigations in humans are scarce. However, the effects observed in animal models suggest that caution should be taken when vaping and that more research needs to be conducted to identify its potential adverse effects on fertility. The prevalence of e-cigarette usage is alarming, and warnings should be made about the impact of vaping on reproductive health. This document reviews the data regarding the impact of e-cigarette use on male and female reproduction.

Evaluation of hazards of electronic -cigarette's liquid refill on testes of mice, complemented by histopathological and chromatographic analysis

Electronic-cigarettes (e-cigarettes) are devices designed to become an alternative to classic cigarettes. Vaping of e-cigarettes and their recharge liquid have become extremely popular among the adolescents; however, its safety is not well established. Evaluation of the components of e-cigarette liquid and their potential effects on testis of adult male mice. This aim will be fulfilled by histological, ultrastructural, and immunohistochemical analysis of mice testis biopsies. Twenty mice were allocated into two groups of equal size. The control group was given regular saline, whereas the treated group was given e-liquid (contains 3 mg of nicotine/kg of body weight) both groups daily intraperitoneally injected for 3 weeks. Analysis of e-liquid by Gas Chromatography-Mass Spectrometric GC/MS demonstrated nicotine, phenol, vanillin, aldehydes, and pyrethroid insecticide. Evaluation of oxidative stress parameters revealed significant reduction of SOD and GPx. Histological results revealed a significant reduction in the height of seminiferous tubules, sloughing of spermatogenic cells, most cells being dark and pyknotic, and thickening of the interstitium with accumulation of PAS positive exudate. Most spermatogenic cells showed degenerative changes as rarefied cytoplasm, ill-defined electron-dense nuclei, and elongated spermatid showed deformity of ectoplasmic specialization. Immunohistochemical studies revealed a significant increase in caspase-3 positive cells and a significant reduction of area % of E-cadherin. The analysis of an available E-liquid demonstrated potentially harmful chemicals that are not shown in the labeling of the product. E-liquid appears to impair anti-oxidant defense and cause degenerative changes in the body and disruption of blood testes barrier BTB. So, e-cigarettes cannot be regarded as a non-harmful smoking replacement.

A Wide Range of Flavoring-Carrier Fluid Adducts Form in E-Cigarette Liquids

A range of flavoring molecules are used in electronic cigarette liquids (e-liquids), some of which have been shown to form cyclic acetal adducts with e-liquid solvent components propylene glycol (PG) and vegetable glycerine (VG). The objective of this study was to identify the range of flavoring molecules which form adducts in e-liquid products. Common e-liquid flavoring molecules (N = 36) from a range of chemical class groups were exposed to PG, VG, or methanol and analyzed by GC-MS over a time frame of 4 weeks to identify possible reaction products. Adduct formation was observed, with 14 of the flavoring molecules reacting with methanol, 10 reacting with PG, and 10 reacting with VG. Furfural PG and VG acetals, valeraldehyde PG and VG acetals, veretraldehyde PG and VG acetals, p-anisaldehyde PG and VG acetals, and piperonal VG acetal were confirmed for the first time. Adducts formed by reaction with ketone-containing flavoring molecules were also observed for the first time. The presence of these acetals was confirmed in 32% of commercial e-liquid products analyzed (N = 142). This study has established a range of flavoring molecules which are able to react with solvent components PG and VG in e-liquids under standard storage conditions. These newly identified adducts need to be further assessed to determine their toxicological safety.

Comparing Message Appeals Employed in Efforts to Prevent E-cigarette Use Among Students in a US University

College students tend to underestimate the risk associated with e-cigarette use while overestimating the prevalence of this behavior. The purpose of this study was to compare the perceived effectiveness of social norms messages to other theoretical appeals regarding the prevention of e-cigarette use. Researchers surveyed 586 college students who assessed five messages. Different appeals were featured in each message. A Rasch Rating Scale Model (RSM) was used to calibrate students' responses to seven items assessing each communication message. The results from the multiple regression models revealed that vape-users were less receptive to the messages than abstainers, and among vape users, males expressed lower message endorsement than females. Overall, the clinical appeal received the highest endorsement in Rasch calibrated logit unit measures, (M = 3.36 for abstainers and M = 2.41 for vape-users), whereas the social norms message was the least favored (M = 1.41 for abstainers and M = 0.22 for vape-users). Qualitative analyses revealed common themes of skepticism and a need for credible scientific information. Findings suggest college students prefer clinical evidence over normative information. An experimental design is needed to determine the extent to which messages influence behavior change.

Effects of chronic electronic cigarettes exposure in inducing respiratory function decline and pulmonary tissue injury - A direct comparison to combustible cigarettes

BACKGROUND

Electronic cigarette (e-cig) use is increasing worldwide, especially among young individuals. Spirometry measures airflow obstruction and is the primary tool for diagnosing/monitoring respiratory diseases in clinical settings. This study aims to assess the effects of chronic e-cig exposure on spirometric traits, and directly compare to conventional combustible-cigarette (c-cig).

METHODS

We employed an e- and c-cig aerosol generation system that resembled human smoking/vaping scenario. Fifty 6-week old C57BL/6 mice were equally divided into five groups and exposed to clean air (control), e-cig aerosol (low- and high-dose), and c-cig aerosol (low- and high-dose), respectively, for 10 weeks. Afterwards, growth trajectory, spirometry and pulmonary pathology were analyzed.

RESULTS

Both e- and c-cig exposure slowed down growth and weight gain. Low dose e-cig exposure (1 h exposure per day) resulted in minimal respiratory function damage. At high dose (2 h exposure per day), e-cig exposure deteriorated 7 spirometry traits but by a smaller magnitude than c-cig exposure. For example, comparing to clean air controls, high dose e- and c-cig exposure increased inspiratory resistance by 24.3% (p = 0.026) and 66.7% (p = 2.6e-5), respectively. Low-dose e-cig exposure increased alveolar macrophage count but did not lead to airway remodeling. In contrast, even low-dose c-cig caused alveoli break down and thickening of the small airway, hallmarks of airway obstructive disease.

CONCLUSIONS

We conducted well-controlled animal exposure experiments assessing chronic e-cig exposure's effects on spirometry traits. Further, mechanistic study characterized airway remodeling, alveolar tissue lesion and inflammation induced by e- and c-cig exposure. Our findings provided scientific and public health insights on e-cig's health consequences, especially in adolescent users.

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.

Carbonyl Profiles of Electronic Nicotine Delivery System (ENDS) Aerosols Reflect Both the Chemical Composition and the Numbers of E-Liquid Ingredients-Focus on the In Vitro Toxicity of Strawberry and Vanilla Flavors

Propylene glycol (PG) and glycerin (G) are the most widely used humectants in electronic nicotine delivery system (ENDS) devices. Carbonyls are present in aerosols produced when ENDS devices heat PG and G. Whether aerosolized PG and G are innocuous to the lungs has not been established. Here, we determined the chemical profiles of ENDS aerosols containing three humectant ratios (30/70, 50/50 and 70/30, PG/VG), for three flavors (strawberry, vanilla and Catalan cream) containing either 12 or 18 mg/mL of nicotine. Additionally, we examined the in vitro toxicity of the strawberry- and vanilla-flavored ENDS aerosol in human lung epithelial cells (BEAS-2B) exposed at the air-liquid interface for 1 h. For strawberry- and vanilla-flavored aerosols produced by a 3rd-generation ENDS device with the same PG/G ratio, the e-liquid nicotine content of 12 and 18 mg/mL did not transfer to the aerosol with substantial differences in concentrations. Our data also indicate the presence of carbonyls in all three flavored e-cig aerosols analyzed, with levels exceeding 1 µg/puff for acetone, butyraldehyde, and acetaldehyde, in strawberry-, vanilla, and Catalan cream-flavored e-cig aerosols, respectively. Furthermore, closed-system ENDS of the fourth generation emitted trace levels of carbonyls in the aerosols (<0.3 µg/puff), while open-system tank-style ENDS of the third generation produced elevated levels of harmful chemicals, including acrolein (>1 µg/puff), formaldehyde (>5 µg/puff), and m- & p-tolualdehyde (>4 µg/puff). Moreover, under non-cytotoxic conditions, BEAS-2B cells exposed to strawberry-flavored aerosols exhibited significantly increased reactive oxygen and nitric oxide species (ROS/NOS) levels in cell media compared to air controls, while vanilla-flavored ENDS aerosols up-regulated the expression of pro-inflammatory and oxidative stress markers. Our data suggest (a) that ENDS aerosol chemical composition will vary based upon the presence and concentration of the initial e-liquid ingredients, with a pronounced impact of the flavoring components; and (b) short-term exposures to flavored ENDS aerosols may impair lung cells' redox signaling in a flavor-specific manner.

Evidence for the coupling of refill liquids content and new particle formation in electronic cigarette vapors

The size and chemical content of particles in electronic cigarette vapors (e-vapors) dictate their fate in the human body. Understanding how particles in e-vapors are formed and their size is critical to identifying and mitigating the adverse consequences of vaping. Thermal decomposition and reactions of the refill liquid (e-liquid) components play a key role in new particles formation. Here we report the evolution of particle number concentration in e-vapors over time for variable mixtures of refill e-liquids and operating conditions. Particle with aerodynamic diameter < 300 nm accounted for up to 17% (or 780 μg/m³) of e-vapors particles. Two events of increasing particle number concentration were observed, 2-3 s after puff completion and a second 4-5 s later. The intensity of each event varied by the abundance of propylene glycol, glycerol, and flavorings in e-liquids. Propylene glycol and glycerol were associated with the first event. Flavorings containing aromatic and aliphatic unsaturated functional groups were strongly associated with the second event and to a lesser extent with the first one. The results indicate that particles in e-vapors may be formed through the heteromolecular condensation of propylene glycol, glycerol, and flavorings, including both parent chemicals and/or their thermal decomposition products.

Chemical characterisation of the vapour emitted by an e-cigarette using a ceramic wick-based technology

Fourth-generation 'pod' e-cigarette devices have been driven by technological advances in electronic atomization of the e-liquid. Use of microporous ceramic as a wicking material improves heating efficiency, but how it affects the chemical emissions of these devices is unclear. We assessed the emissions of a pod e-cigarette with innovative ceramic wick-based technology and two flavoured e-liquids containing nicotine lactate and nicotine benzoate (57 and 18 mg mL-1 nicotine, respectively). Among the studied harmful and potentially harmful constituents (HPHCs) listed by the US FDA and/or WHO TobReg, only 5 (acetone, acetaldehyde, formaldehyde, naphthalene and nornicotine) were quantified at levels of 0.14 to 100 ng puff-1. In the combustible cigarette (Kentucky reference 1R6F), levels were from 0.131 to 168 µg puff-1. Nicotine levels ranged 0.10-0.32 mg puff-1 across the 3 study products. From the 19 proposed HPHCs specifically of concern in e-cigarettes, only 3 (glycerol, isoamyl acetate and propylene glycol) were quantified. The low/undetectable levels of HPHCs reflect not only the optimal operating conditions of the e-cigarette, including an efficient supply of e-liquid by the ceramic wick without overheating, but also the potential of the e-cigarettes to be used as an alternative to combustible cigarettes.

Computational modeling method to estimate secondhand exposure potential from exhalations during e-vapor product use under various real-world scenarios

Potential secondhand exposure of exhaled constituents from e-vapor product (EVP) use is a public health concern. We present a computational modeling method to predict air levels of exhaled constituents from EVP use. We measured select constituent levels in exhaled breath from adult e-vapor product users, then used a validated computational model to predict constituent levels under three scenarios (car, office, and restaurant) to estimate likely secondhand exposure to non-users. The model was based on physical/thermodynamic interactions between air, vapor, and particulate phase of the aerosol. Input variables included space setting, ventilation rate, total aerosol amount exhaled, and aerosol composition. Exhaled breath samples were analyzed after the use of four different e-liquids in a cartridge-based EVP. Nicotine, propylene glycol, glycerin, menthol, formaldehyde, acetaldehyde, and acrolein levels were measured and reported based on a linear mixed model for analysis of covariance. The ranges of nicotine, propylene glycol, glycerin, and formaldehyde in exhaled breath were 89.44-195.70 µg, 1199.7-3354.5 µg, 5366.8-6484.7 µg, and 0.25-0.34 µg, respectively. Acetaldehyde and acrolein were below detectable limits; thus, no estimated exposure to non-EVP users is reported. The model predicted that nicotine and formaldehyde exposure to non-users was substantially lower during EVPs use compared to cigarettes. The model also predicted that exposure to propylene glycol, glycerin, nicotine and formaldehyde among non-users was below permissible exposure limits.

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.

Aerosol, vapor, or chemicals? College student perceptions of harm from electronic cigarettes and support for a tobacco-free campus policy

Objective: This study is the first to examine the influence of e-cigarette emission phrasing on perceived harm of secondhand exposure, and whether harm perception was associated with support for a tobacco-free campus policy. Participants: In the fall 2018 and spring 2019 semesters, 52 sections of a college English course (N = 791 students) were cluster randomized to one of three conditions ("vapor," "aerosol," or "chemicals") assessing harm of secondhand exposure to e-cigarette emissions. Methods: Regression models adjusted for demographic characteristics, tobacco use, and other potential confounders. Results: Compared to the "vapor" condition, "chemicals" and "aerosol" conditions were associated with increased odds of perceiving secondhand exposure to e-cigarettes to be harmful/very harmful (AOR = 2.0, p < 0.01). Greater perceived harm of secondhand e-cigarette exposure was associated with increased odds of supporting a tobacco-free campus policy (AOR = 2.22, p < 0.001). Conclusions: Health campaigns should use accurate terminology to describe e-cigarette emissions, rather than jargon that conveys lower risk.

On the toxicity of e-cigarettes consumption: Focus on pathological cellular mechanisms

Tobacco smoking remains without a doubt one of the leading causes of premature death worldwide. In combination with conventional protocols for smoking cessation, e-cigarettes have been proposed as a useful tool to quit smoking. Advertised as almost free of toxic effects, e-cigarettes have rapidly increased their popularity, becoming a sought-after device, especially among young people. Recently some health concerns about e-cigarette consumption are being raised. It is well known that they can release several toxic compounds, some of which are carcinogenic to humans, and emerging results are now outlining the risks related to the onset of respiratory and cardiovascular diseases and even cancer. The present review shows the emerging evidence about the role of technical components of the devices, the e-liquid composition as well as customization by consumers. The primary topics we discuss are the main toxicological aspects associated with e-cigarette consumption, focusing on the molecular pathways involved. Here it will be shown how exposure to e-cigarette aerosol induces stress/mitochondrial toxicity, DNA breaks/fragmentation following the same pathological pathways triggered by tobacco smoke, including the deregulation of molecular signalling axis associated with cancer progression and cell migration. Risk to fertility and pregnancy, as well as cardiovascular risk associated with e-cigarette use, have also been reported.

Effect Comparison of E-Cigarette and Traditional Smoking and Association with Stroke-A Cross-Sectional Study of NHANES

Introduction: Tobacco use is one of the most significant risk factors for stroke. Besides traditional cigarettes and combustible products, the use of e-cigarettes and electronic nicotine delivery products has been widespread among young adults in the recent era. Furthermore, the trend of vaping has increased over the last decade. However, the relationship between e-cigarettes and stroke is largely unknown. The aim of this study was to evaluate the prevalence and identify the relationship between e-cigarette smoking and stroke. Methods: A cross-sectional study was performed using the NHANES database of the US population. Adults with a history of smoking were considered in our study and divided into three groups, e-cigarette users, traditional, and dual smokers. The Chi-squared test, Wilcoxon rank-sum test, and multivariable logistic regression analysis were used to identify the prevalence and association of e-cigarette consumption and stroke. Results: Out of a total of 266,058 respondents from 2015 to 2018, we found 79,825 respondents who smoked e-cigarettes (9.72%) or traditional (29.37%) or dual smoking (60.91%). Stroke prevalence among e-cigarette smokers was 1.57%. Stroke was more prevalent among traditional smokers than among e-cigarette smokers. (6.75% vs. 1.09%; p < 0.0001) E-cigarette smokers had early onset of stroke in comparison with traditional smokers. (median age: 48 vs. 59 years; p < 0.0001). Among females with stroke, the prevalence of e-cigarette use was higher in comparison with traditional smoking (36.36% vs. 33.91%; p < 0.0001). Among the stroke population, the prevalence of e-cigarette use was higher among Mexican-Americans (21.21% vs. 6.02%) and other Hispanics (24.24% vs. 7.70%) compared with traditional smoking (p < 0.0001). The regression analysis found higher odds of stroke history among e-cigarette users than traditional smokers [aOR: 1.15; 95% CI: 1.15−1.16)]. Conclusion: Though stroke was more prevalent in traditional smokers, the incidence of stroke was early-in-onset and was strongly associated with e-cigarette use compared to traditional smokers. We have also identified vascular effects of e-cigarettes components as possible triggers for the stroke.

JUUL™ing and Heating Lead to a Worsening of Arterial Stiffness

Background: The widespread use of the JUUL™ device ignited a discussion about the effects these products have on harm reduction. Therefore, we conducted a study directly comparing the JUUL™ device with a cigarette, a heated tobacco product, and a nicotine-free e-cigarette to examine the acute effects on arterial stiffness. Methods: This crossover-designed study examines 20 occasional smokers (age 25.2 ± 2.5 years). Study participants used each of the four smoking devices for a duration of 5 min following a protocol. Peripheral blood pressure and parameters of arterial stiffness and endothelial vasodilator function such as the reactive hyperemia index and the augmentation index were measured using the EndoPAT™2000 before and after. Results: In addition to significant peripheral hemodynamic changes after 5 and 10 min (p < 0.05), the reactive hyperemia index showed a significant decrease for all devices 15 min after consumption and remained significantly decreased after 60 min (p < 0.01). The augmentation index adjusted for a heart rate of 75 bpm increased significantly for all devices 15 and 60 min after consumption (p < 0.01). Conclusions: In conclusion, the increases in blood pressure and arterial stiffness are similar after smoking, JUUL™ing, heating, and vaping. These changes may be associated with an increase in cardiovascular risks; however, an evaluation of the long-term effects of JUUL™ing, vaping and heating is needed.

Assessment of worker chemical exposures in California vape shops

E-cigarettes are battery-operated devices that heat a liquid mixture to make an aerosol that is inhaled, or vaped, by the user. Vape shops are retail environments designed to fulfill customer demand for diverse e-liquid flavors and hardware options, which create unique worker exposure concerns. To characterize exposures to vape shop workers, especially to flavoring chemicals associated with known respiratory toxicity, this study recruited vape shops from the San Francisco Bay Area. In six shops, we measured air concentrations for volatile organic compounds, formaldehyde, flavoring chemicals, and nicotine in personal and/or area samples; analyzed components of e-liquids vaped during field visits; and assessed metals on surface wipe samples. Interviews and observations were conducted over the course of a workday in the same six shops and interviews were performed in an additional six where sampling was not conducted. Detections of the alpha-diketone butter flavoring chemicals diacetyl and/or 2,3-pentanedione were common: in the headspace of purchased e-liquids (18 of 26 samples), in personal air samples (5 of 16), and in area air samples (2 of 6 shops). Two exceedances of recommended exposure limits for 2,3-pentanedione (a short-term exposure limit and an 8-hr time-weighted average) were measured in personal air samples. Other compounds detected in the area and personal air samples included substitutes for diacetyl and 2,3-pentanedione (acetoin and 2,3-hexanedione) and compounds that may be contaminants or impurities. Furthermore, a large variety (82) of other flavoring chemicals were detected in area air samples. None of the 12 shops interviewed had a health and safety program. Six shops reported no use of any personal protective equipment (PPE) (e.g., gloves, chemical resistant aprons, eye protection) and the others stated occasional use; however, no PPE use was observed during any field investigation day. Recommendations were provided to shops that included making improvements to ventilation, hygiene, use of personal protective equipment, and, if possible, avoidance of products containing the alpha-diketone flavoring chemicals. Future research is needed to evaluate the long-term health risks among workers in the vape shop retail industry and for e-cigarette use generally. Specific areas include further characterizing e-liquid constituents and emissions, evaluating ingredient health risks, evaluating the contributions of different routes of exposure (dermal, inhalation, and ingestion), and determining effective exposure mitigation measures.

Cardiovascular functions and arterial stiffness after JUUL use

INTRODUCTION

The rapid growth in the e-cigarette market after the launch of JUUL e-cigarettes led to much discussion on the potential benefits and risks of pods, JUUL devices, and conventional e-cigarettes compared with combustible cigarettes. Independent data are required to assess the effects of these products on cardiovascular surrogate parameters and cardiovascular risk.

METHODS

We conducted a single-center three-arm study comparing combustible cigarettes with JUUL e-cigarettes with the old and new technology. We recruited 32 participants who were active smokers (n=15) or vapers (n=17) and performed a total of 39 measurements before and 5, 15, and 30 minutes, after participants smoked a combustible cigarette or vaped a JUUL e-cigarette with the new or old technology. Measurements included peripheral and central blood pressures and parameters of arterial stiffness, including pulse wave velocity and augmentation index.

RESULTS

Peripheral systolic blood pressure, central blood pressure, and peripheral pulse rate increased significantly in all three groups (each p<0.05). Heart rate (HR) changes lasted significantly longer than blood pressure changes. The augmentation index and pulse wave velocity increased in all three groups, and a multivariate analysis of variance showed that the increases were independent of systolic blood pressure, sex, age, device, and HR.

CONCLUSIONS

Changes in blood pressure and arterial stiffness are similar after cigarette smoking and JUUL use. These changes may be associated with an increased cardiovascular risk compared with no product use. However, a long-term follow-up evaluation of JUUL use and a head-to-head comparison with conventional e-cigarettes are still needed.