The chemistry and toxicology of vaping

Understanding time to vaping onset in childhood and adolescence: A dual systems model approach

BACKGROUND

Vaping has grown in prevalence among youth populations over the past decade and has been promoted as a safer alternative to smoking despite the potential health risks. There is a dearth of research which has examined the timing of onset of vaping from childhood into adolescence. Childhood predictors vaping onset have also been understudied. This study sought to address gaps in the literature by examining timing of vaping onset, relevance of childhood levels of dual systems model constructs (sensation-seeking, impulse control) for predicting differential onset, and the potential that childhood predictors may vary in the magnitude of their effects depending on age.

METHODS

Data from the Adolescent Brain Cognitive Development study were analyzed. Survival analysis plotted the differential timing of vaping onset. Cox proportional hazard models examined the relevance of baseline sensation-seeking and impulse control for predicting differential timing of vaping onset. Time-varying coefficients in the Cox model were used to examine the interactions between predictors and age.

RESULTS

Findings indicated that the vast majority of vaping onset in the sample occurred during the teenage years. Greater sensation-seeking and lower impulse control at baseline significantly predicted quicker time to vaping and greater risk overall for vaping. These relationships did not vary in effect magnitude by age.

CONCLUSIONS

Consistent with prior research on tobacco use (smoking e-cigarettes, etc.), sensation-seeking and impulse control were significant predictors of vaping. Message framing strategies may have utility for addressing impulse control and/or sensation-seeking issues that may precipitate vaping onset.

Immunological Effects of Electronic Cigarette Use: A Review of Current Evidence

Electronic cigarettes (EC) have emerged as a popular alternative to traditional tobacco products, but their impact on immune function has raised significant health concerns. This review explores the immunological effects of EC exposure, focusing on innate and adaptive immune responses. Electronic cigarette aerosol (ECA) induces widespread inflammation. These changes compromise immune cell function, impairing neutrophil chemotaxis, phagocytosis, and oxidative burst while increasing macrophage and dendritic cell recruitment and activation. ECA also disrupts epithelial barriers, increasing susceptibility to bacterial and viral infections. Studies show enhanced biofilm formation in bacteria such as Staphylococcus aureus and Streptococcus pneumoniae and impaired antiviral responses against pathogens like influenza A and SARS-CoV-2. Additionally, EC exposure modulates adaptive immunity, affecting T and B cell function and increasing systemic inflammatory markers. The long-term consequences of these immunological disruptions include heightened risks for chronic inflammatory diseases, respiratory infections, and potentially autoimmune conditions. The widespread adoption of EC, particularly among younger users, poses a growing public health challenge. As the popularity of vaping continues to rise, these immunological disruptions could result in increased healthcare burdens in the future, with higher rates of infections, chronic inflammatory diseases, and immune system-related disorders among those who begin using e-cigarettes at a young age. Understanding the full scope of EC-related health risks is essential for informing public health policies and protecting future generations from the potential long-term effects of vaping.

Pharmacists' Perspectives on Nicotine Vaping Products (NVPs) for Smoking Cessation in Australia: A Qualitative Analysis

Vaping, particularly the use of nicotine vaping products (NVPs), has emerged as a public health concern. The regulatory environment surrounding NVPs in Australia has rapidly evolved, shifting from a prescription-only model to availability through community pharmacies. Pharmacists play a critical role in addressing vaping-related health concerns. This study explores Australian pharmacists' perspectives on their professional roles and the support needed to manage vaping-related enquiries. Qualitative semi-structured interviews were conducted with 25 practicing pharmacists using a topic guide developed from the current literature and team expertise. The interviews were transcribed verbatim and analysed thematically using an inductive approach to identify key themes. Key themes included risk perception, professional vaping health-related services, professional practice and other support-related needs. Pharmacists expressed significant uncertainty about the risks and harms associated with vaping. There was apprehension around the regulatory complexity of supplying NVPs, and participants called for greater education and support, particularly around NVP's place in smoking cessation and potential vaping cessation services. Effective public health messaging and risk communication about vaping are crucial. At the centre of recent legislative changes, pharmacists require training and professional support to address vaping-related scenarios and provide counselling that aligns with individual risk perceptions, ensuring NVP use is clinically appropriate.

Effects of Electronic Cigarettes on Periodontal Health: A Systematic Review and Meta-Analysis

OBJECTIVES

The use of electronic cigarettes "e-cigarettes," or vaping is growing in popularity, especially among adolescents and young adults. While the effects of cigarette smoking on oral health are well-established, the exact impact that e-cigarettes may have on dental tissues is still uncertain. The aim of the current review was to summarize evidence related to the effect of vaping on the periodontal health status of e-cigarette users.

METHODS

A comprehensive electronic search was performed using PubMed, Web of Science, and Scopus databases, until January 31st, 2024. Two independent reviewers participated in the screening of studies, data extraction, and assessment of the included studies. Any disagreements were resolved by a third reviewer the quality assessment was done using the Newcastle-Ottawa Scale to assess the risk of bias. A frequentist meta-analysis was performed using R Statistical Software. The random effects model was adopted. Data were described as mean difference (MD) and 95% confidence interval (CI). A p-value of ≤ .05 was deemed statistically significant.

RESULTS

Ten studies met the eligibility criteria. Overall, the findings were consistent, with most studies showing that e-cigarette users are at greater risk of periodontal disease than nonsmokers, but that they have a lower risk than cigarette smokers. Pooling results showed lower mean probing depth (PD) among nonsmokers than e-smokers (MD: -1.91; 95% CI: [-3.36: -0.47]; p-value = .01) while it was higher among cigarette smokers in participants with periodontitis (MD:0.43; 95%CI: [0.08:0.79]; p-value = .02). Compared to e-smoking, nonsmokers had lower PI (MD: -20.63; 95%CI: [-28.04: -13.21]; p-value < .001) while cigarette smokers had higher PI (MD: 4.88; 95% CI: [-1.52:11.29]; p-value = .135). Among participants with periodontitis, only cigarette smokers had significantly higher PI (MD: 4.53; 95%CI: [1.94:7.13]; p-value < .001).

CONCLUSION

Based on the current analysis, conventional cigarette smoking is the most detrimental to periodontal health among the groups compared in all included studies. This indicates that traditional cigarettes have a more severe impact on periodontal tissues than do e-cigarettes. The data suggest a gradient of risk where nonsmokers have the lowest risk, e-cigarette users have a moderate risk, and cigarette smokers have the highest risk for periodontal health issues.

Exploring E-Vape Aerosol Penetration into Paranasal Sinuses: Insights from Patient-Specific Models

Background: Acute and chronic sinusitis significantly impact patients' quality of life. Effective drug delivery to paranasal sinuses is crucial for treating these conditions. However, medications from conventional devices like nasal drops, sprays, and nebulized mists often fail to penetrate the small ostia and reach the sinuses. This study aims to assess the effectiveness of e-vape-generated aerosols entering and filling paranasal sinus cavities, particularly the maxillary sinus. Methods: The aerosol droplets were generated using an electronic vaporizer (e-vape) and were composed solely of vegetable glycerin (VG) and propylene glycol (PG). Patient-specific, transparent nose-sinus models, including one with post-uncinectomy surgery, were used to evaluate the effectiveness of these e-vape-generated VG-PG aerosols in entering the sinuses under unidirectional and bidirectional airflow conditions. Visualizations from various nasal model views and lighting conditions were recorded. Particle size distribution measurements of the e-vape aerosol were conducted using a laser diffraction particle size analyzer. Results: E-vape-generated VG-PG droplets effectively enter paranasal sinuses under specific administration conditions. E-vape aerosol droplet size measurements revealed a mean particle size ranging from 2.895 to 3.359 μm, with a median particle size (D50) averaging 2.963 μm. The speed of aerosol entering the paranasal sinuses is directly proportional to the ostia size; larger ostia result in faster sinus entry. A continuous moderate flow is necessary to gradually fill the paranasal sinus cavities. The aerosol entry into sinuses was observed at 2 L/min and decreased with increasing flow rate. The mechanisms of aerosol entry involve maintaining a positive pressure gradient across the ostial canal, a non-equilibrium transverse pressure distribution, and a two-way flow through the ostium. Gravitational forces and recirculation currents further enhance the deposition of e-vape aerosols. Comparative tests showed that traditional delivery devices exhibited limited penetration into paranasal sinuses. Conclusions: This study demonstrated that e-vape-generated aerosols could serve as a vehicle for delivering active pharmaceutical ingredients (APIs) directly to the paranasal sinuses, improving treatment outcomes.

External hair contamination from cannabis and "light cannabis" delivered by smoking and vaping: An in vitro study

External contamination of hair by cannabis smoking requires a careful evaluation in forensic toxicology. Medical and recreational cannabis are increasingly consumed by e-cigarettes, which give rise to side-stream vapor. Moreover, products containing low Δ9-tetrahydrocannabinol (Δ9-THC) and rich in cannabidiol (CBD) started spreading legally. The goal of the present study was to assess whether hair analysis could allow to distinguish the type of delivered product, with low or high Δ9-THC, and the delivering mode, by smoking or vaping. Contamination of blank hair was mimicked by in vitro exposure to low- (0.4%) and high-Δ9-THC (9.7%) products delivered by smoking and vaping within a small confined system. Cannabis vaping extracts were prepared to deliver identical target Δ9-THC doses. Eighty samples were analyzed by ultrahigh-performance liquid chromatography mass spectrometry and quantified for Δ9-THC and CBD. After contamination by cannabis smoking, THC levels were in line with past in vitro and in vivo studies. Samples exposed to cannabis (169.30 ng/mg) showed significantly higher Δ9-THC than hair exposed to "light cannabis" (35.54 ng/mg), and the opposite was seen for the CBD/Δ9-THC ratio. Hair contaminated by vaping or smoking did not show a statistically different Δ9-THC content. Under our in vitro conditions, hair analysis might allow to discriminate whether external contamination is determined by products containing low or high Δ9-THC, but not the delivering mode. More research is needed in real-life conditions, to see whether the same also applies to the interpretation of forensic casework.

Vaping Possible Negative Effects on Lungs: State-of-the-Art From Lung Capacity Alteration to Cancer

Vaping has emerged as a popular alternative to traditional smoking. It produces smokeless vapour by heating an e-liquid mixture in an atomizer. This paper delves into the current state of knowledge surrounding electronic cigarettes, exploring the gap between the perceived safety of e-liquids and the emerging evidence of their harmful effects when inhaled. As we navigate this intricate landscape, it is crucial to unravel the complexities of vaping and its implications for public health. We conducted a three-layer systematic review of the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analyses of Observational Studies in Epidemiology (MOOSE). The search was performed in three layers, including the first layer, the effect of vaping on lung function; the second layer, the effect of vaping on lung structure and inducing lung injury; and the third layer, the physiopathologic effect of vaping on the lung and a possible carcinogenic effect. Exposure to e-cigarette vapour reduced lung ventilation in adult male Long-Evans rats, indicating impaired lung function. In male Wistar rats, vaping was associated with a decrease in lung air volume and denser lung tissue structure. Studies on guinea pigs showed that vaping caused acute bronchoconstriction, contributing to lung function impairment. A case study of a young man with an E-cigarette and vaping-induced lung injury (EVALI) highlighted the detrimental effects of vaping on human lung function. The EVALI outbreak in the USA was linked to harmful substances in vapes, such as vitamin E acetate and THC, leading to serious lung injuries, including pneumonia and bronchiolitis. Vaping poses significant health risks, especially to young adults, and misconceptions regarding its safety persist despite evidence of its potential to cause various lung diseases. While vaping has positioned itself as a smoking cessation aid, the discussion surrounding its impact on lung health requires careful consideration. The lack of conclusive evidence on the long-term effects of vaping underscores the need for further research. However, existing data suggest that vaping is not without risks, and its potential association with respiratory issues and cancer underscores the urgency of public health interventions.

Sex-specific alterations in pulmonary metabolic, xenobiotic and lipid signalling pathways after e-cigarette aerosol exposure during adolescence in mice

BACKGROUND

E-cigarette use is now prevalent among adolescents and young adults, raising concerns over potential adverse long-term health effects. Although it is hypothesised that e-cigarettes promote inflammation, studies have yielded conflicting evidence. Our previous work showed that JUUL, a popular e-cigarette brand, elicited minimal lung inflammation but induced significant molecular changes in adult C57BL/6 mice.

METHODS

Now, we have profiled immunological and proteomic changes in the lungs of adolescent male and female BALB/c and C57BL/6 mice exposed to a flavoured JUUL aerosol containing 18 mg/mL of nicotine for 14 consecutive days. We evaluated changes in the immune composition by flow cytometry, gene expression levels by reverse transcription-quantitative PCR and assessed the proteomic profile of the lungs and bronchoalveolar lavage (BAL) by tandem mass tag-labelled mass spectroscopy.

RESULTS

While there were few significant changes in the immune composition of the lungs, proteomic analysis revealed that JUUL exposure caused significant sex-dependent and strain-dependent differences in lung and BAL proteins that are implicated in metabolic pathways, including those related to lipids and atherosclerosis, as well as pathways related to immune function and response to xenobiotics. Notably, these changes were more pronounced in male mice.

CONCLUSIONS

These findings raise the possibility that vaping dysregulates numerous biological responses in lungs that may affect disease risk, disproportionally impacting males and raising significant concerns for the future health of male youth who currently vape.

A review of vaping's health effects, treatment, and policy implications: Nursing's call to action

ABSTRACT

The emergence and subsequent surge in popularity of electronic nicotine delivery systems (ENDS), especially among adolescents and young adults, have reshaped the landscape of tobacco consumption, including use patterns and beliefs as well as therapeutic approaches to the condition. The health implications of ENDS are a cause for concern among NPs, as they include severe nicotine dependence, mental health consequences, and adverse effects on respiratory and cardiac systems, among other issues. This article focuses on the health implications of vaping across the lifespan and emphasizes the need for NPs to evaluate ENDS use consistently across age groups and offer age-appropriate treatment within the clinical setting. Importantly, although vaping is prevalent among various age groups, most tobacco use, including vaping, begins and becomes established during adolescence. This back-to-school season therefore marks an ideal time for NPs to educate their pediatric patients, along with their parents or caregivers, about the widespread effects of vaping on health, and it also serves as a reminder to screen for the condition in adults, regardless of smoking history. To combat this trend on a larger scale, NPs can further advocate for community health by promoting youth prevention programs and supporting policy initiatives aimed at curbing ENDS use.

Direct health implications of e-cigarette use: a systematic scoping review with evidence assessment

Background

E-cigarettes are often marketed as a less harmful alternative to traditional tobacco cigarettes. Despite their popularity, the evidence regarding their effects on human health remains unclear and is filled with complexities.

Objectives

This systematic review aims to elucidate the direct effects of electronic cigarette use on human health, carefully distinguishing between the specific characteristics of the populations studied.

Methodology

Adhering to the PRISMA guidelines, we conducted a comprehensive search in PubMed/Medline, Web of Science, Scopus, and Google Scholar databases without date restrictions, including articles in both Spanish and English. This approach enabled the identification and analysis of primary studies to understand the direct effect of electronic cigarettes on human health.

Results

A total of 33 studies were included that evaluated cardiovascular, pulmonary, renal, weight and fertility effects. Only five studies analyzed e-cigarettes in healthy populations and seven studies compared healthy individuals against smokers. The effects evaluated on smokers or former tobacco smokers were apparently positive, however, among healthy individuals, increased heart rate, mean arterial pressure, oxidative stress, alteration of respiratory epithelial cells and increased airflow resistance were found.

Conclusion

Smokers or former smokers who switch to e-cigarettes may reduce their exposure to carcinogens and lower their risk of developing severe health issues associated with conventional smoking. However, in healthy individuals who have never smoked traditional cigarettes, the use of e-cigarettes introduces several cardiovascular and respiratory adverse effects. These findings suggest that while e-cigarettes can be a strategic harm reduction tool for smokers, they are not a safe option for non-smokers.

Investigation of the in vitro toxic effects induced by real-time aerosol of electronic cigarette solvents using microfluidic chips

The safety of propylene glycol (PG) and vegetable glycerin (VG) as solvents in electronic cigarette liquid has received increasing attention and discussion. However, the conclusions derived from toxicity assessments conducted through animal experiments and traditional in vitro methodologies have consistently been contentious. This study constructed an original real-time aerosol exposure system, centered around a self-designed microfluidic bionic-lung chip, to assess the biological effects following exposure to aerosols from different solvents (PG, PG/VG mixture alone and PG/VG mixture in combination with nicotine) on BEAS-2B cells. The study aimed to investigate the impact of aerosols from different solvents on gene expression profiles, intracellular biomarkers (i.e., reactive oxygen species content, nitric oxide content, and caspase-3/7 activity), and extracellular biomarkers (i.e., IL-6, IL-8, TNF-α, and malondialdehyde) of BEAS-2B cells on-chip. Transcriptome analyses suggest that ribosomal function could serve as a potential target for the impact of aerosols derived from various solvents on the biological responses of BEAS-2B cells on-chip. And the results showed that aerosols of PG/VG mixtures had significantly less effect on intracellular and extracellular biomarkers in BEAS-2B cells than aerosols of PG, whereas increasing nicotine levels might elevate these effects of aerosol from PG/VG mixture.

Understanding the Cardiovascular Fallout of E-cigarettes: A Comprehensive Review of the Literature

E-cigarettes (ECs) deliver chemicals, including nicotine. They can cause respiratory distress, addiction, cardiovascular effects, and death. More research is needed, especially regarding their impact on the cardiovascular system (CVS) and during pregnancy. Our article aims to fill this gap by summarizing studies elaborating upon the current impact of ECs and the components thereof on the CVS. Acute respiratory distress outbreaks, nicotine addiction, CVS effects, and deaths have been occasionally reported within this cohort, although these events are not uncommon with neighboring age groups. Randomized control trials implying ECs have some contribution toward quitting smoking have been studied. To regulate EC distribution, the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) have created key checkpoints. Additionally, taxation, pricing, age restriction, and media campaigns could be modulated to significantly reduce illicit sales. Education to the users, distributors, and regulators about this product can also play an aiding role in promoting responsible EC use. Another strategy about licensing could be employed, which could incentivize genuine resellers. The effects on CVS and child-bearing by ECs are grim, which calls for strict regulation, awareness, and avoidance by the teetotaler public. They may help individuals stop smoking but not without harming themselves. Strict regulations are necessary to prevent non-judicious use of these devices.

Characteristics of second-hand exposure to aerosols from e-cigarettes: A literature review since 2010

In recent years, the use of electronic vaping products (also named e-cigarettes) has increased due to their appealing flavors and nicotine delivery without the combustion of tobacco. Although the hazardous substances emitted by e-cigarettes are largely found to be much lower than combustible cigarettes, second-hand exposure to e-cigarette aerosols is not completely benign for bystanders. This work reviewed and synthesized findings on the second-hand exposure of aerosols from e-cigarettes and compared the results with those of the combustible cigarettes. In this review, different results were integrated based upon sampling locations such as residences, vehicles, offices, public places, and experimental exposure chambers. In addition, the factors that influence the second-hand exposure levels were identified by objectively reviewing and integrating the impacts of combustible cigarettes and e-cigarettes on the environment. It is a challenge to compare the literature data directly to assess the effect of smoking/vaping on the indoor environment. The room volume, indoor air exchange rate, puffing duration, and puffing numbers should be considered, which are important factors in determining the degree of pollution. Therefore, it is necessary to calculate the "emission rate" to normalize the concentration of pollutants emitted under various experimental conditions and make the results comparable. This review aims to increase the awareness regarding the harmful effects of the second-hand exposure to aerosols coming from the use of cigarettes and e-cigarettes, identify knowledge gaps, and provide a scientific basis for future policy interventions with regard to the regulation of smoking and vaping.

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.

Cannabis Science and Therapeutics: An Overview for Clinicians

Cannabis-based therapeutics have garnered increasing attention in recent years as patients seek alternative treatments for various medical conditions. This narrative review provides a comprehensive overview of the science behind the medical use of cannabis, focusing on the medical evidence for commonly treated conditions. In addition, the review addresses the practical considerations of using cannabis as a therapeutic agent, offering insights into dosing strategies, variations in cannabinoid formulation, and individual patient responses. Precautions, adverse consequences, and drug interactions are also discussed, with a focus on patient safety and the potential risks associated with cannabis use.

An evaluation of the cannabinoid content of the liquid and thermal degradation analysis of cannabis-labeled vape liquids

Cannabidiol (CBD) vape pen usage has been on the rise given the changing political and scientific climate as well as the promotion of these delivery systems as a more accessible and lower-risk option for consumers. Despite being marketed as a safer way to use cannabis, CBD vape liquids are sold without restrictions or meticulous quality control procedures such as toxicological and clinical assessment, standards for product preservation, or investigative degradation analyses. Nine CBD-labeled vape liquid samples purchased and manufactured in the United States were evaluated and assessed for cannabinoid content. Quantification and validation of cannabinoids and matrix components was accomplished using gas and liquid chromatography with mass spectrometry analysis (GC-MS and LC-MS/MS) following liquid-liquid extraction with methanol. Samples degraded by temperature (analyzed by GC-MS) showed a greater disparity from the labeled CBD content compared with samples analyzed as purchased (by LC-MS/MS). Thermal degradation of the vape liquids showed increased levels of tetrahydrocannabinol (THC). Also, extended time and temperature degradation were evaluated in vape liquids by storing them for 15 months and then varying temperature conditions before analysis, which indicated CBD transformed into other cannabinoids leading to different cannabinoid content within the vape samples. Evaluation conducted on these vape liquids indicated the route of exposure, storage conditions, and length of storage could expose consumers to unintended cannabinoids and showed a concerning level of disagreement between the products' labeled cannabinoid content and the results generated by these analyses.

Temporal Association Between Vaping and Risk of Cardiac Events

OBJECTIVE

To describe our early observations with sudden cardiac arrest (SCA) and sudden death (SD) in patients using vape products.

PATIENTS AND METHODS

A retrospective analysis of Mayo Clinic's Windland Smith Rice Genetic Heart Rhythm Clinic and Sudden Death Genomics Laboratory was performed on all SCA survivors and decedents who presented between January 1, 2007, and December 31, 2021, to identify patients/decedents with a history of vaping. Data abstraction included patient demographics, clinical characteristics, and documented use of vape products.

RESULTS

Among 144 SCA survivors and 360 SD victims, there were six individuals (1%; 3 females) with unexplained SCA (n=4) or SD (n=2) that was temporally associated with vaping use with a mean age at sentinel event of 23±5 years. The SCA survivors include a 19-year-old male who was resuscitated from documented ventricular fibrillation 40 minutes after vaping and a 19-year-old male who was resuscitated from ventricular fibrillation a few hours post vaping. The first SD victim was a 19-year-old female with exercise-induced asthma who died in her sleep after vaping that evening. Autopsy results showed eosinophilic infiltrates in the lung tissue and death was attributed to bronchial asthma. The second vaping-associated death involved a 26-year-old male whose autopsy attributed the death to acute respiratory distress syndrome.

CONCLUSION

We have identified six young individuals with a history of vaping who experienced a near fatal episode or a tragic SD. Although larger cohort studies are needed to quantify the actual risk of SD, it seems prudent to sound an early warning about vaping's potential lethality.

The comprehensive review about elements accumulation in industrial hemp (Cannabis sativa L.)

Cannabis sativa L., commonly known as industrial hemp, is a versatile plant with applications ranging from medicinal to agricultural and industrial uses. Despite its benefits, there is a notable gap in regulatory toxicology, in understanding the extent of element accumulation in hemp, which is critical due to its ability to absorb various elements from the soil, including heavy metals (Pb, Cd, Hg, and As), uptakes potential toxic elements (e.g., Sb, Sn, Sr, Bi, Tl), problematic elements (Ni, Cr, Co), and essential elements (Zn, Cu, Fe, Mn). The paper aims to enrich current understandings by offering a comprehensive analysis of elements absorption in industrial hemp. This study emphasizes the potential health risks linked with hemp consumption including regulatory toxicology aspects: limits, Permitted Daily Exposures (PDE), recommendations in different countries and from different agencies/bodies (like the WHO and the EU) based on route of administration, jurisdiction and actual literature review. This review contributes significantly to the knowledge base on hemp safety, serving as a valuable resource for researchers, regulatory bodies, and industry stakeholders.

Thermal reaction products and formation pathways of two monoterpenes under in situ thermal desorption conditions that mimic vaping coil temperatures

Vaping has become more popular and different brands and types of vaping devices have rapidly emerged. However, little is known about the potential health risks of human inhalation exposures to the volatile chemicals in the vapour, which includes both directly vaporised components of vaping liquid and their reaction products formed during vaping processes. This study investigated reaction products of two monoterpenes (α-pinene and terpinolene) that are used as flavouring agents in vaping liquids with a focus on the identification of reaction products and their formation pathways. The thermal desorption was conducted under an in situ condition that is in the range of heating coil temperature in vaping by thermally desorbing the chemicals at a temperature range of 100-300 °C. Additional clean air was introduced during the thermal desorption. 36 and 29 reaction products were identified from α-pinene and terpinolene, respectively, at a relative concentration of 0.01% and greater in the desorbed mixture. 3-Carene was the dominant reaction product of α-pinene, while reaction products of terpinolene was dominated by p-isopropenyltoluene. Several reaction pathways including ring opening, allylic oxidation, cyclo-etherification, Wagner-Meerwein rearrangement, epoxidation, cleavage and removal of partial structure, and dehydration were involved in the formation of various reaction products. These pathways and resulting relative concentrations of residual parent compound and reaction products were influenced by both temperature and amount of air present during thermal desorption. The study results demonstrate possible existence of reaction products from thermally labile chemicals like monoterpenes in vaping aerosols and can help inform policies regulating vaping devices and products to protect public health.

A 21-Year-Old Woman with Sickle Cell Disease and Vaso-Occlusive Pain Associated with Using an Electronic Nicotine Dispensing System (E-Cigarette or Vape) - a Case Report

BACKGROUND Sickle cell disease is an inherited blood disorder that leads to multisystem complications. The heterogeneous course of sickle cell disease is due to both genetic modifiers and environmental factors. Cigarette smoking is a strong risk factor for sickle cell complications and even secondhand exposure to tobacco smoke can be detrimental for individuals with sickle cell disease. However, no prior reports have associated e-cigarettes and sickle cell vaso-occlusive pain. CASE REPORT A 21 year old woman presented with sickle cell disease SS complicated by frequent pain, multiple acute chest syndrome episodes, sickle cell nephropathy, and avascular necrosis of the left hip, plus mild intermittent asthma. She developed pain in the ribs and back after her first use of e-cigarettes. After 4 days of home pain management, she came to the Emergency Department. She was mildly hypoxic and received supplemental oxygen. Chest radiograph did not show airspace consolidation, and the sites of pain were consistent with her prior pain episodes, so the diagnosis was sickle cell vaso-occlusive pain. Her hemoglobin was more than 2 g/dL below baseline and she received a red blood cell transfusion on hospital day 2. Overall, this was among her more severe pain episodes. CONCLUSIONS The rising popularity of e-cigarettes, also known as vapes or Electronic Nicotine Delivery Systems (ENDS), is partly due to the misconception that they are safer than traditional cigarettes. Although firm conclusions will depend on studies designed to provide rigorous evidence, this case suggests that the acute adverse effects of ENDS might trigger complications of sickle cell disease, especially with asthma as a comorbidity.

Interventions to prevent or cease electronic cigarette use in children and adolescents

BACKGROUND

The prevalence of e-cigarette use has increased globally amongst children and adolescents in recent years. In response to the increasing prevalence and emerging evidence about the potential harms of e-cigarettes in children and adolescents, leading public health organisations have called for approaches to address increasing e-cigarette use. Whilst evaluations of approaches to reduce uptake and use regularly appear in the literature, the collective long-term benefit of these is currently unclear.

OBJECTIVES

The co-primary objectives of the review were to: (1) evaluate the effectiveness of interventions to prevent e-cigarette use in children and adolescents (aged 19 years and younger) with no prior use, relative to no intervention, waitlist control, usual practice, or an alternative intervention; and (2) evaluate the effectiveness of interventions to cease e-cigarette use in children and adolescents (aged 19 years and younger) reporting current use, relative to no intervention, waitlist control, usual practice, or an alternative intervention. Secondary objectives were to: (1) examine the effect of such interventions on child and adolescent use of other tobacco products (e.g. cigarettes, cigars types, and chewing tobacco); and (2) describe the unintended adverse effects of the intervention on individuals (e.g. physical or mental health of individuals), or on organisations (e.g. intervention displacement of key curricula or learning opportunities for school students) where such interventions are being implemented.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, Ovid PsycINFO, EBSCO CINAHL, and Clarivate Web of Science Core Collection from inception to 1 May 2023. Additionally, we searched two trial registry platforms (WHO International Clinical Trials Registry Platform; US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov), Google Scholar, and the reference lists of relevant systematic reviews. We contacted corresponding authors of articles identified as ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), including cluster-RCTs, factorial RCTs, and stepped-wedge RCTs. To be eligible, the primary targets of the interventions must have been children and adolescents aged 19 years or younger. Interventions could have been conducted in any setting, including community, school, health services, or the home, and must have sought to influence children or adolescent (or both) e-cigarette use directly. Studies with a comparator of no intervention (i.e. control), waitlist control, usual practice, or an alternative intervention not targeting e-cigarette use were eligible. We included measures to assess the effectiveness of interventions to: prevent child and adolescent e-cigarette use (including measures of e-cigarette use amongst those who were never-users); and cease e-cigarette use (including measures of e-cigarette use amongst children and adolescents who were e-cigarette current-users). Measures of e-cigarette use included current-use (defined as use in the past 30 days) and ever-use (defined as any lifetime use).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of references, with any discrepancies resolved through consensus. Pairs of review authors independently assessed the full-text articles for inclusion in the review. We planned for two review authors to independently extract information from the included studies and assess risk of bias using the Cochrane RoB 2 tool. We planned to conduct multiple meta-analyses using a random-effects model to align with the co-primary objectives of the review. First, we planned to pool interventions to prevent child and adolescent e-cigarette use and conduct two analyses using the outcome measures of 'ever-use' and 'current-use'. Second, we planned to pool interventions to cease child and adolescent e-cigarette use and conduct one analysis using the outcome measure of 'current-use'. Where data were unsuitable for pooling in meta-analyses, we planned to conduct a narrative synthesis using vote-counting approaches and to follow the Cochrane Handbook for Systematic Reviews of Interventions and the Synthesis Without Meta-analysis (SWiM) guidelines.

MAIN RESULTS

The search of electronic databases identified 7141 citations, with a further 287 records identified from the search of trial registries and Google Scholar. Of the 110 studies (116 records) evaluated in full text, we considered 88 to be ineligible for inclusion for the following reasons: inappropriate outcome (27 studies); intervention (12 studies); study design (31 studies); and participants (18 studies). The remaining 22 studies (28 records) were identified as ongoing studies that may be eligible for inclusion in a future review update. We identified no studies with published data that were eligible for inclusion in the review.

AUTHORS' CONCLUSIONS

We identified no RCTs that met the inclusion criteria for the review, and as such, there is no evidence available from RCTs to assess the potential impact of interventions targeting children and adolescent e-cigarette use, tobacco use, or any unintended adverse effects. Evidence from studies employing other trial designs (e.g. non-randomised) may exist; however, such studies were not eligible for inclusion in the review. Evidence from studies using non-randomised designs should be examined to guide actions to prevent or cease e-cigarette use. This is a living systematic review. We search for new evidence every month and update the review when we identify relevant new evidence. Please refer to the Cochrane Database of Systematic Reviews for the current status of this review.

PM1 exposure and spatial transmission of nicotine from the simulated second-hand vapor of pod-based electronic cigarettes

Electronic cigarettes (E-cigarettes) have gained significant popularity in recent years as a substitute for combustible cigarettes. However, there is growing concern regarding the safety of E-cigarette products for both the users and those exposed passively to second-hand emissions, which contain nicotine and other toxic substances. In particular, the characteristics of second-hand PM1 exposure and the transmission of nicotine from E-cigarettes remain unclear. In this study, the untrapped mainstream aerosols from the E-cigarette and smoke from cigarettes were exhausted by the smoking machines which were operated under standardized puffing regimes to simulate second-hand vapor or smoke exposure. The concentrations and components of PM1 released from cigarettes and E-cigarettes were compared under varying environmental conditions and regulated using a heating, ventilation, and air conditioning (HVAC) system. Additionally, the ambient nicotine concentrations and the size distribution of the generated aerosols were determined at different distances from the release source. Results showed that PM1 accounted for the highest proportion (98 %) of the released particulate matter (PM1, PM2.5, and PM10). The mass median aerodynamic diameter (MMAD) of cigarette smoke (0.5 ± 0.01 μm, geometric standard deviation (GSD) 1.97 ± 0.1) was smaller than that of E-cigarette aerosols (1.06 ± 0.14 μm, GSD 1.79 ± 0.19). The PM1 concentrations and chemical components were effectively reduced when the HVAC system was utilized. Nicotine concentrations in E-cigarette aerosols were comparable to those of combustible cigarette emissions when close to the exposure source (0 m), while they declined more rapidly than cigarette smoke emissions with increasing distance from the source. Furthermore, the maximum nicotine concentrations occurred in 1 μm and 0.5 μm particles in E-cigarette and cigarette emissions, respectively. These results provide a scientific basis for the assessment of E-cigarette and cigarette aerosol passive exposure risks, guiding the development of environmental and human health control measures for these products.

Impact of Vaping on Lungs: An Indian Prospect

Electronic cigarettes, or vape pens, have gained popularity among young people due to their attractive appearance, but they also have numerous side effects. These devices come in various shapes, sizes, and costs, with many brands and various flavors to choose from. As of now, there are around 2,807 people hospitalized in the United States due to vaping. Electronic cigarettes are illegal in many countries, with laws varying from country to country. The health service has been criticized for the implementation of the ban, with states implementing month-long drives and submitting reports. The Indian Police have also conducted raids and arrested five individuals under the 2019 ban on Electronic Cigarettes (Production, Manufacture, Trade, Transport, Sale, Distribution, Storage, and Advertisement) Act. The history of vapes can be traced back to the invention of the first electric vaporizer in 1927 by Joseph Robinson. Other pioneers like Herbert Gilbert and Jed Rose developed nicotine fixes using refined smoke. The vape was made in 2003 by Chinese smoker Hon Lik, who created the device as a better option to traditional smoking.

E-cigarettes and arrhythmogenesis: a comprehensive review of pre-clinical studies and their clinical implications

Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully studied and understood. Originally designed as devices to assist with those trying to quit traditional combustible cigarette use, their popularity has attracted use by teens and adolescents who traditionally have not smoked combustible cigarettes. Acute effects on the heart have been shown to be similar to traditional combustible cigarettes, including increased heart rate and blood pressure. The main components of electronic cigarettes that contribute to these arrhythmic effects are found in the e-liquid that is aerosolized and inhaled, comprised of nicotine, flavourings, and a combination of vegetable glycerin (VG) and propylene glycol (PG). Nicotine can potentially induce both ventricular and atrial arrhythmogenesis, with both the atrial and ventricular effects resulting from the interactions of nicotine and the catecholamines they release via potassium channels. Atrial arrhythmogenesis, more specifically atrial fibrillation, can also occur due to structural alterations, which happens because of nicotine downregulating microRNAs 133 and 590, both post-transcriptional growth factor repressors. Liquid flavourings and the combination of PG and VG can possibly lead to arrhythmic events by exposing users to acrolein, an aldehyde that stimulates TRPA1 that in turn causes a change towards sympathetic activation and autonomic imbalance. The design of these electronic delivery devices is constantly changing; therefore, it has proven extremely difficult to study the long-term effects on the heart caused by electronic cigarettes but will be important to understand given their rising popularity. The arrhythmic effects of electronic cigarettes appear similar to traditional cigarettes as well; however, a comprehensive review has not been compiled and is the focus of this article.

A Single 10-Minute E-cigarette Vapor Exposure Reduces Tidal Volume and Minute Ventilation in Normoxia and Normobaric Hypoxia in Adult Rats

The present study investigated the effects of a single 10-minute exposure to e-cigarette vapor on ventilation in adult male Long-Evans rats. Ventilation was recorded using awake, unrestrained whole-body plethysmography. Baseline recordings were taken the day before full-body exposure to either room air (n = 9; air control group) or e-cigarette vapor (n = 9; treatment group). Post-exposure recordings were taken immediately after the 10-minute room air or vapor exposure. As part of the ventilation protocol, in addition to recording the subject's ventilation in room air, the subjects were also exposed to 10% oxygen (balanced with nitrogen) to assess the effects of e-cigarette vapor on an increased drive to breathe. Ventilation data were analyzed using a 2x2x2 mixed-model ANOVA measuring treatment (vape vs. air) x time (baseline vs. post-treatment) x condition (normoxia vs. hypoxia) for breathing frequency, tidal volume, and minute ventilation. Breathing frequency increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), with no effect of time (baseline vs. post-treatment) for either group. Tidal volume increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), and an effect of time (baseline vs. post-treatment) was observed (p = 0.010) for the vape group. Minute ventilation increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), and an effect of time (baseline vs. post-treatment) was observed (p < 0.001) for the vape group. In conclusion, immediately following a single 10-minute e-cigarette vapor exposure, both tidal volume and minute ventilation were reduced during normoxia and normobaric hypoxia, indicating a decrease in ventilation after a single 10-minute e-cigarette vapor exposure. Furthermore, this exposure also blunted the physiological response to acute hypoxia exposure. Subjects in the vape group, while breathing more rapidly as expected, experienced shallower breathing than the air group during hypoxia. The findings in this study confirm that vaping could result in reduced lung function.

Exploring Differences in Daily Vaping of Nicotine and Cannabis among People Who Use Drugs in New Zealand

Background: Little is known about daily vaping of different substances, particularly cannabis. Aim: To explore daily vaping of cannabis and nicotine products in a sample of people who use drugs in New Zealand. Method: The online New Zealand Drug Trends convenience survey (N = 23,500) was promoted to those aged 16+ via a targeted Facebook™ campaign, with 9,042 reporting vaping in the past six months. Multivariate logistic regression models were fitted to identify predictors of daily vaping of: (i) nicotine e-liquids, (ii) no-nicotine e-liquids, (iii) cannabis e-liquids/oils, (iv)cannabis herb. Results: Forty-two percent of past 6-month vapers used a vaporizing device "daily or near daily" (n = 3,508). Nicotine was most common substance used by daily vapers (96%), followed by dry herb cannabis (12%), no-nicotine e-liquids (10%) and cannabis e-liquid (6%). Daily vaping of no-nicotine e-liquids was associated with abstinence from tobacco use. Frequency of cannabis use was negatively correlated with daily vaping of nicotine liquids and positively correlated with daily vaping of no-nicotine and herbal cannabis. Younger age strongly predicted daily vaping of nicotine and no-nicotine liquids, but the reverse association was observed for daily vaping of herbal cannabis. Māori were less likely to daily vape cannabis herb than NZ Europeans. Daily vaping of both cannabis e-liquid and cannabis herb was associated with medicinal cannabis use. Conclusion: Daily vapers of nicotine and cannabis differed by several characteristics. Younger age group is at risk of daily vaping nicotine and non-nicotine, while herbal cannabis vaping is associated with older and medicinal use, suggesting a need for a nuanced vape policy response.

An ecological momentary assessment study to examine covariates and effects of concurrent and simultaneous use of electronic cigarettes and marijuana among college students

INTRODUCTION

The prevalence of concurrent and simultaneous use of e-cigarette and marijuana among college students is high. Yet, the literature was mainly based on cross-sectional surveys with emphasis on the smoking route. This is the first ecological momentary assessment (EMA) study that examined the vaping route of nicotine-marijuana co-use and the associated short-term psychological effects.

METHODS

This study recruited 686 college student e-cigarette users to participate in an on-line survey and 7-day EMA. Frequent marijuana users (247) - using marijuana weekly or daily - were compared with infrequent/non-users (439) on academic performance, e-cigarette use patterns, and dependence and respiratory symptoms. EMA data from the frequent users were used to study the association between marijuana vaping and e-cigarette consumption and the short-term psychological effects of e-cigarette and marijuana use.

RESULTS

The results show that e-cigarette users who frequently used marijuana tended to have lower academic performance, be involved in higher-risk use patterns, and have higher levels of e-cigarette dependence, marijuana problems, and respiratory symptoms, compared to infrequent/non-users. Marijuana vaping was associated with a higher level of e-cigarette consumption. E-cigarette use and marijuana use were both associated with higher levels of positive affect, physiological sensation, and craving for e-cigarettes. While marijuana use was linked to a lower level of negative affect, e-cigarette use did not have a significant effect. Further, none of the interaction effects between e-cigarette and marijuana use on psychological states were significant.

CONCLUSIONS

The results showed additive effects of e-cigarette and marijuana use although the hypothesized synergistic effects were not supported.

Specific biomarker comparison in current smokers, e-cigarette users, and non-smokers

INTRODUCTION

This study aims to address the existing gap in the literature, while adding evidence, by comparing tobacco-specific biomarkers (cotinine and nitrosamines: NNK, NNAL, NNN), and other biomarkers of e-cigarette use (humectants: glycerol, 1,2-PD, 1,3-PD) according to five study groups.

METHODS

A pooling analysis including two different studies was conducted. In both analyses, we took saliva samples from smokers (n = 409) and non-smokers (n = 154), dual tobacco and e-cig users (n = 92), exclusive e-cig user with nicotine (n = 158), and exclusive e-cig users without nicotine (n = 38). We analyzed and compared the geometric means (GM) and geometric standard deviations (GSD) of the concentration of tobacco-specific biomarkers, and e-cigarette biomarkers among groups. We used log-linear models adjusted for sex and age to model the change percentage and their 95% confidence intervals.

RESULTS

Cotinine was significantly higher in nicotine consumers and in e-cigarette users without nicotine when compared to non-smokers. TSNAs were generally significantly lower in non-smokers and higher in nicotine consumers. NNN and NNAL were lower in e-cigarette users with nicotine comparted to smokers, and NNN was higher in e-cigarette users without nicotine when compared to non-smokers. No differences were found in humectant biomarkers between e-cigarette groups.

CONCLUSIONS

Although there was a reduction in TSNAs in e-cigarette exclusive users compared to smokers, and a reduction of cotinine concentrations in e-cigarette exclusive users without nicotine compared to smokers, there are still high levels of these biomarkers when compared to non-smokers, which may be a clue towards the harmful effect of e-cigarettes.

Electronic Cigarette Use during Pregnancy: Is It Harmful?

Although combustible cigarette smoking rates have declined in recent years, alternative tobacco product use, particularly electronic cigarette use ("vaping"), has increased among young adults. Recent studies indicate that vaping during pregnancy is on the rise, possibly due to the perception that it is a safer alternative to combustible cigarette smoking. However, e-cigarette aerosols may contain several newer, potentially toxic compounds, including some known developmental toxicants that may adversely impact both the mother and the fetus. However, there is paucity of studies that have examined the effects of vaping during pregnancy. While the adverse perinatal outcomes of cigarette smoking during pregnancy are well established, the specific risks associated with inhaling vaping aerosols during pregnancy requires more research. In this article, we discuss the existing evidence and knowledge gaps on the risks of vaping during pregnancy. Studies that investigate vaping-associated systemic exposure and its effects (i.e., biomarker analyses) and maternal and neonatal clinical health outcomes are needed to reach more robust conclusions. We particularly emphasize the need to go beyond comparative studies with cigarettes, and advocate for research that objectively evaluates the safety of e-cigarettes and other alternative tobacco products.

Fraction of Free-Base Nicotine in Simulated Vaping Aerosol Particles Determined by X-ray Spectroscopies

A new generation of electronic cigarettes is exacerbating the youth vaping epidemic by incorporating additives that increase the acidity of generated aerosols, which facilitate uptake of high nicotine levels. We need to better understand the chemical speciation of vaping aerosols to assess the impact of acidification. Here we used X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to probe the acid-base equilibria of nicotine in hydrated vaping aerosols. We show that, unlike the behavior observed in bulk water, nicotine in the core of aqueous particles was partially protonated when the pH of the nebulized solution was 10.4, with a fraction of free-base nicotine (α_FB) of 0.34. Nicotine was further protonated by acidification with equimolar addition of benzoic acid (α_FB = 0.17 at pH 6.2). By contrast, the degree of nicotine protonation at the particle surface was significantly lower, with 0.72 < α_FB < 0.80 in the same pH range. The presence of propylene glycol and glycerol completely eliminated protonation of nicotine at the surface (α_FB = 1) while not affecting significantly its acid-base equilibrium in the particle core. These results provide a better understanding of the role of acidifying additives in vaping aerosols, supporting public health policy interventions.

Biomarkers of Electronic Nicotine Delivery Systems (ENDS) Use

This perspective summarizes available evidence on biomarkers of exposure in electronic nicotine delivery system (ENDS) users to aid the overall assessment of the health consequences of using ENDS. Identification of novel biomarkers of exposure specific to ENDS use remains challenging because chemicals emitted from ENDS devices have many familiar sources. The biomarker levels of many tobacco-related toxicants measured in biological samples collected from ENDS users did not differ significantly from non-users, except for nicotine metabolites and a small number of biomarkers of exposure to volatile organic compounds and tobacco-specific tobacco nitrosamines. Several studies have shown that while exposed to nicotine, long-term exclusive ENDS users showed significantly lower levels of toxicant biomarkers than cigarette smokers. Studies have also shown that concurrent users of ENDS and combustible cigarettes ('dual users') are not reducing overall exposure to harmful toxicants compared to exclusive cigarette smokers. Because of an absence of validated ENDS-specific biomarkers, we recommend combining several biomarkers to differentiate tobacco product user groups in population-based studies and monitor ENDS compliance in randomized controlled trials. Using a panel of biomarkers would provide a better understanding of health effects related to ENDS use.

External Factors Modulating Vaping-Induced Thermal Degradation of Vitamin E Acetate

Despite previous studies indicating the thermal stability of vitamin E acetate (VEA) at low temperatures, VEA has been shown to readily decompose into various degradation products such as alkenes, long-chain alcohols, and carbonyls such as duroquinone (DQ) at vaping temperatures of <200 °C. While most models simulate the thermal decomposition of e-liquids under pyrolysis conditions, numerous factors, including vaping behavior, device construction, and the surrounding environment, may impact the thermal degradation process. In this study, we investigated the role of the presence of molecular oxygen (O2) and transition metals in promoting thermal oxidation of e-liquids, resulting in greater degradation than predicted by pure pyrolysis. Thermal degradation of VEA was performed in inert (N2) and oxidizing atmospheres (clean air) in the absence and presence of Ni-Cr and Cu-Ni alloy nanopowders, metals commonly found in the heating coil and body of e-cigarettes. VEA degradation was analyzed using thermogravimetric analysis (TGA) and gas chromatography/mass spectrometry (GC/MS). While the presence of O2 was found to significantly enhance the degradation of VEA at both high (356 °C) and low (176 °C) temperatures, the addition of Cu-Ni to oxidizing atmospheres was found to greatly enhance VEA degradation, resulting in the formation of numerous degradation products previously identified in VEA vaping emissions. O2 and Cu-Ni nanopowder together were also found to significantly increase the production of OH radicals, which has implications for e-liquid degradation pathways as well as the potential risk of oxidative damage to biological systems in real-world vaping scenarios. Ultimately, the results presented in this study highlight the importance of oxidation pathways in VEA thermal degradation and may aid in the prediction of thermal degradation products from e-liquids.

Disposable E-Cigarettes and Associated Health Risks: An Experimental Study

The use of electronic nicotine delivery systems (ENDS), including disposable e-cigarettes, has been prevalent. Existing chemical analyses of ENDS focused on e-liquids rather than aerosols and failed to consider particle sizes and aerosol respiratory deposition fractions, which are key factors for inhalation doses. This study investigated the organic chemical and metal constituents in size-segregated ENDS aerosol and assessed the deposited doses and health risks of these substances. Aerosol chemical analyses were conducted on two popular disposable ENDS products: Puff Bar (Grape) and Air Bar (Watermelon Ice). An ENDS aerosol was generated and delivered into a Micro-Orifice Uniform Deposit Impactor to collect size-segregated aerosol samples, in which organic chemicals and metals were analyzed. Daily and lifetime doses for each chemical were estimated. Cancer and non-cancer risk assessments were conducted based on the deposited doses. We found that e-cigarette aerosol contains certain harmful organic chemicals and metals documented to result in respiratory problems. Estimated respiratory cancer risks corresponding to chromium from both ENDS products and nickel from Air Bar (Watermelon Ice) were substantially above the conventionally acceptable risk. The method, findings, and implications can contribute to the extant literature of ENDS toxicity studies as well as inform tobacco regulation and future large-scale studies.

Transfer of Metals to the Aerosol Generated by an Electronic Cigarette: Influence of Number of Puffs and Power

Electronic cigarettes (e-cigarettes) are increasing in popularity despite uncertainties about their health hazards. Literature studies have shown that e-cigarettes may be a source of toxic heavy metal exposure to the user, but the mechanism by which metals are transferred from the e-cigarette parts into the aerosol plume that is inhaled by the user is poorly understood. The goal of this study was to quantify the potentially harmful heavy metals chromium, nickel, copper, and lead systematically during the simulated use of a mod-type e-cigarette in order to better understand the mechanism of metal transfer from the e-cigarette parts into the aerosol plume and into the liquid in the storage tank. Aerosol was collected and aliquots of the remaining liquid in the storage tank were collected from 0 to 40 puffs in 10 puff increments and analyzed with atomic absorption spectroscopy. It was found that the concentration of metals increased in both the aerosol and tank liquid the more times the e-cigarette was puffed, but at varying rates for each element and depending on the power applied to the heating coil. For copper, lead, and nickel, the concentrations of metals in the aerosol and tank increased with increasing power but for chromium, the concentration varied with power. Additionally, it was observed that chromium and nickel concentrations were greater in the aerosol than in tank liquid, consistent with the direct transfer of those metals to the aerosol from heating of the nichrome coil element used in this study. For copper and lead, the concentrations were similar or greater in the tank compared to the aerosol, consistent with transfer first into the storage tank liquid, followed by vaporization into the aerosol.

In-situ TD-GCMS measurements of oxidative products of monoterpenes at typical vaping temperatures: implications for inhalation exposure to vaping products

Vaping is gaining in popularity. However, there is still much that remains unknown about the potential risk and harms of vaping. Formation of oxidative products is one of such areas that are not well understood. In this study, we used an in-situ thermal desorption GC/MS method to investigate the formation of oxidative products of several monoterpenes at or below typical vaping temperatures. Among the five tested monoterpenes, the unchanged portion of the parent compound in the vapour varied from 97 to 98% for myrcene to 11–28% for terpinolene. The majority of formed oxidative products in the vapour have a molecular weight of 134 (loss of two hydrogens), 150 (insertion of one oxygen and loss of two hydrogen atoms) or 152 (insertion of one oxygen atom). Three products, likely to be p-(1-propenyl)-toluene, β-pinone and fenchol were also observed. This is the first in-situ thermal desorption GC/MS study to investigate the possible formation of oxidative products of monoterpenes, one of the major components in vaping liquids, at temperatures that are relevant to the vaping process. Although the toxicity of inhaling these oxidative products is not clear yet, allergic and irritation reactions associated with oxidized monoterpene oils are well documented. Therefore, potential adverse effects of inhaling these oxidative products during vaping could be investigated to help support human risk assessment.

Temperature dependence of emission product distribution from vaping of vitamin E acetate

Nearly two years after vitamin E acetate (VEA) was identified as the potential cause of the 2019–2020 outbreak of e-cigarette, or vaping product-associated lung injuries (EVALI), the toxicity mechanisms of VEA vaping are still yet to be fully understood. Studies since the outbreak have found that e-liquids such as VEA undergo thermal degradation during the vaping process to produce various degradation products, which may pose a greater risk of toxicity than exposure to unvaped VEA. Additionally, a wide range of customizable parameters–including the model of e-cigarette used, puffing topography, or the applied power/temperature used to generate aerosols–have been found to influence the physical properties and chemical compositions of vaping emissions. However, the impact of heating coil temperature on the chemical composition of VEA vaping emissions has not been fully assessed. In this study, we investigated the emission product distribution of VEA vaping emissions produced at temperatures ranging from 176 to 356°C, corresponding to a variable voltage vape pen set at 3.3 to 4.8V. VEA degradation was found to be greatly enhanced with increasing temperature, resulting in a shift towards the production of lower molecular weight compounds, such as the redox active duroquinone (DQ) and short-chain alkenes. Low temperature vaping of VEA resulted in the production of long-chain molecules, such as phytol, exposure to which has been suggested to induce lung damage in previous studies. Furthermore, differential product distribution was observed in VEA degradation products generated from vaping and from pyrolysis using a tube furnace in the absence of the heating coil at equivalent temperatures, suggesting the presence of external factors such as metals or oxidation that may enhance VEA degradation during vaping. Overall, our findings indicate that vaping behavior may significantly impact the risk of exposure to toxic vaping products and potential for vaping-related health concerns.

E-Cigarettes-a review of the evidence-harm versus harm reduction

The World Health Organization estimates there are 1.1 billion cigarette smokers across the globe and that tobacco related deaths number 7 million per year. Electronic nicotine delivery systems (ENDS) are available to contribute options for smoking cessation and include e-cigarettes, e-hookahs, vape pens, mods, and vaping. The growing use of ENDS, or e-cigarettes, in the US and globally across populations is dramatic. Although users may think that e-cigarettes are less harmful than combustible tobacco products, the evidence shows that there are known risks and harms for users. E-cigarettes have varying amounts of toxicants, nicotine, and carcinogens and put the user at risk for lung diseases and COVID-19 similar to smokers. Currently, most governing bodies have not approved e-cigarettes as a smoking cessation tool but do state if a person has failed conventional smoking cessation treatments that e-cigarettes used alone for the short term may help those to quit combustible tobacco and nicotine. A shared decision-making approach should be used when discussing e-cigarettes as a harm reduction tool. More studies and long-term data are needed to assess potential benefits and harms. What is known is that prevention efforts and policy are needed to avoid adolescents and other vulnerable populations from initiating tobacco or e-cigarette use.

Influence of E-Liquid Humectants, Nicotine, and Flavorings on Aerosol Particle Size Distribution and Implications for Modeling Respiratory Deposition

Electronic cigarette, or vaping, products are used to heat an e-liquid to form an aerosol (liquid droplets suspended in gas) that the user inhales; a portion of this aerosol deposits in their respiratory tract and the remainder is exhaled, thereby potentially creating opportunity for secondhand exposure to bystanders (e.g., in homes, automobiles, and workplaces). Particle size, a critical factor in respiratory deposition (and therefore potential for secondhand exposure), could be influenced by e-liquid composition. Hence, the purposes of this study were to (1) test the influence of laboratory-prepared e-liquid composition [ratio of propylene glycol (PG) to vegetable glycerin (VG) humectants, nicotine, and flavorings] on particle size distribution and (2) model respiratory dosimetry. All e-liquids were aerosolized using a second-generation reference e-cigarette. We measured particle size distribution based on mass using a low-flow cascade impactor (LFCI) and size distribution based on number using real-time mobility sizers. Mass median aerodynamic diameters (MMADs) of aerosol from e-liquids that contained only humectants were significantly larger compared with e-liquids that contained flavorings or nicotine (p = 0.005). Humectant ratio significantly influenced MMADs; all aerosols from e-liquids prepared with 70:30 PG:VG were significantly larger compared with e-liquids prepared with 30:70 PG:VG (p = 0.017). In contrast to the LFCI approach, the high dilution and sampling flow rate of a fast mobility particle sizer strongly influenced particle size measurements (i.e., all calculated MMAD values were &lt; 75 nm). Dosimetry modeling using LFCI data indicated that a portion of inhaled particles will deposit throughout the respiratory tract, though statistical differences in aerosol MMADs among e-liquid formulations did not translate into large differences in deposition estimates. A portion of inhaled aerosol will be exhaled and could be a source for secondhand exposure. Use of laboratory-prepared e-liquids and a reference e-cigarette to standardize aerosol generation and a LFCI to measure particle size distribution without dilution represents an improved method to characterize physical properties of volatile aerosol particles and permitted determination of MMAD values more representative of e-cigarette aerosol in situ, which in turn, can help to improve dose modeling for users and bystanders.

1,2-Propylene Glycol: A Biomarker of Exposure Specific to e-Cigarette Consumption

Over the past decade, new emerging tobacco and nicotine-delivery products have changed the tobacco landscape. Especially, electronic cigarettes (ECs) have been suggested to be considered for tobacco harm reduction, reinforcing the need to identify novel biomarkers of exposure (BoE) specific to the EC use as this would complement exposure assessment and product compliance monitoring. Therefore, a sensitive LC-MS/MS method for the quantification of 1,2-propylene glycol (PG) and glycerol (G), the main e-liquid constituents, was established. PG and G were analyzed in plasma and urine samples from a clinical study comparing five nicotine product user groups, users of combustible cigarettes (CC), electronic cigarettes (EC), heated tobacco products (HTP), oral tobacco (OT), and oral/dermal nicotine delivery products (used for nicotine replacement therapy, NRT) with a control group of non-users (NU). Data demonstrate significantly elevated PG levels in urine and plasma in EC users compared to users of CC, HTP, NRT, OT as well as NU. In addition, PG in plasma and urine of vapers significantly correlated with nicotine (plasma) and total nicotine equivalents (urine), biomarkers reflecting product consumption, emphasizing the high specificity of PG as a BoE for EC consumption. We therefore suggest the use of PG as BoE in urine and/or plasma in order to monitor EC use compliance in exposure assessments.