Sugar and Aldehyde Content in Flavored Electronic Cigarette Liquids

Metabolic and Other Endocrine Elements with Regard to Lifestyle Choices: Focus on E-Cigarettes

Our objective was to overview recent data on metabolic/endocrine disorders with respect to e-cigarette (e-cig) use. This is a narrative review; we researched English, full-length, original articles on PubMed (between January 2020 and August 2023) by using different keywords in the area of metabolic/endocrine issues. We only included original clinical studies (n = 22) and excluded case reports and experimental studies. 3 studies (N1 = 22,385; N2 = 600,046; N3 = 5101) addressed prediabetes risk; N1 showed a 1.57-fold increased risk of dual vs. never smokers, a higher risk that was not confirmed in N2 (based on self-reported assessments). Current non-smokers (N1) who were dual smokers still have an increased odd of prediabetes (a 1.27-fold risk increase). N3 and another 2 studies addressed type 2 diabetes mellitus (DM): a lower prevalence of DM among dual users (3.3%) vs. cigarette smoking (5.9%) was identified. 6 studies investigated obesity profile (4 of them found positive correlations with e-cig use). One study (N4 = 373,781) showed that e-cig use was associated with obesity in the general population (OR = 1.6, 95%CI: 1.3-2.1, p < 0.05); another (N5 = 7505, 0.82% were e-cig-only) showed that obesity had a higher prevalence in dual smokers (51%) vs. cig-only (41.2%, p < 0.05), while another (N6 = 3055) found that female (not male) e-cig smokers had higher body mass index vs. non-smokers. Data on metabolic syndrome (MS) are provided for dual smokers (n = 2): one case-control study found that female dual smokers had higher odds of MS than non-smokers. The need for awareness with respect to potential e-cig--associated medical issues should be part of modern medicine, including daily anamnesis. Whether the metabolic/endocrine frame is part of the general picture is yet to be determined. Surveillance protocols should help clinicians to easily access the medical background of one subject, including this specific matter of e-cig with/without conventional cigarettes smoking and other habits/lifestyle elements, especially when taking into consideration metabolism anomalies.

Mechanisms of E-Cigarette Vape-Induced Epithelial Cell Damage

E-cigarette use has been reported to affect cell viability, induce DNA damage, and modulate an inflammatory response resulting in negative health consequences. Most studies focus on oral and lung disease associated with e-cigarette use. However, tissue damage can be found in the cardio-vascular system and even the bladder. While the levels of carcinogenic compounds found in e-cigarette aerosols are lower than those in conventional cigarette smoke, the toxicants generated by the heat of the vaping device may include probable human carcinogens. Furthermore, nicotine, although not a carcinogen, can be metabolized to nitrosamines. Nitrosamines are known carcinogens and have been shown to be present in the saliva of e-cig users, demonstrating the health risk of e-cigarette vaping. E-cig vape can induce DNA adducts, promoting oxidative stress and DNA damage and NF-kB-driven inflammation. Together, these processes increase the transcription of pro-inflammatory cytokines. This creates a microenvironment thought to play a key role in tumorigenesis, although it is too early to know the long-term effects of vaping. This review considers different aspects of e-cigarette-induced cellular changes, including the generation of reactive oxygen species, DNA damage, DNA repair, inflammation, and the possible tumorigenic effects.

The Role of Electronic Cigarettes in Dental Caries: A Scoping Review

Dental caries, a predominant childhood and adolescence affliction, has numerous factors implicated in its pathogenesis. Electronic cigarettes (ECs) have recently gained popularity among the younger population. Various factors, such as the EC liquid composition and aerosols, are associated with the development of dental caries. This review explains numerous EC-related factors which may lead to dental caries. An electronic search was conducted in Medline (Pubmed), Scopus, and Embase databases to evaluate the original research investigating the role of ECs in developing dental caries. About 12 included studies in the review indicated that factors such as the composition of e-liquids and aerosols are significant in the progression of dental caries. Specifically, cariogenic sugars such as sucrose, fructose, glucose, aldehydes, and flavors such as menthol, cinnamon, and strawberry in the e-liquids contribute to dental caries. They are toxic to oral commensals such as Streptococcus gordonii, Streptococcus mitis, Streptococcus intermedius, and Streptococcus oralis and promote the proliferation of cariogenic pathogens such as Streptococcus mutans (S. mutans) which causes dental caries. However, further validation of the effects of ECs on the development of dental caries is warranted through clinical trials.

Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association

Vaping and electronic cigarette (e-cigarette) use have grown exponentially in the past decade, particularly among youth and young adults. Cigarette smoking is a risk factor for both cardiovascular and pulmonary disease. Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products. The outbreak of e-cigarette or vaping product use-associated lung injury in the United States in 2019, which led to >2800 hospitalizations, highlighted the risks of e-cigarettes and vaping products. Currently, all e-cigarettes are regulated as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device. Because youth prevalence of e-cigarette and vaping product use was as high as 27.5% in high school students in 2019 in the United States, it is critical to assess the short-term and long-term health effects of these products, as well as the development of interventional and public health efforts to reduce youth use. The objectives of this scientific statement are (1) to describe and discuss e-cigarettes and vaping products use patterns among youth and adults; (2) to identify harmful and potentially harmful constituents in vaping aerosols; (3) to critically assess the molecular, animal, and clinical evidence on the acute and chronic cardiovascular and pulmonary risks of e-cigarette and vaping products use; (4) to describe the current evidence of e-cigarettes and vaping products as potential tobacco-cessation products; and (5) to summarize current public health and regulatory efforts of e-cigarettes and vaping products. It is timely, therefore, to review the short-term and especially the long-term implications of e-cigarettes and vaping products on cardiopulmonary health. Early molecular and clinical evidence suggests various acute physiological effects from electronic nicotine delivery systems, particularly those containing nicotine. Additional clinical and animal-exposure model research is critically needed as the use of these products continues to grow.

Langmuir-Blodgett Films with Immobilized Glucose Oxidase Enzyme Molecules for Acoustic Glucose Sensor Application

In this work, a sensitive coating based on Langmuir-Blodgett (LB) films containing monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) with an immobilized glucose oxidase (GOx) enzyme was created. The immobilization of the enzyme in the LB film occurred during the formation of the monolayer. The effect of the immobilization of GOx enzyme molecules on the surface properties of a Langmuir DPPE monolayer was investigated. The sensory properties of the resulting LB DPPE film with an immobilized GOx enzyme in a glucose solution of various concentrations were studied. It has shown that the immobilization of GOx enzyme molecules into the LB DPPE film leads to a rising LB film conductivity with an increasing glucose concentration. Such an effect made it possible to conclude that acoustic methods can be used to determine the concentration of glucose molecules in an aqueous solution. It was found that for an aqueous glucose solution in the concentration range from 0 to 0.8 mg/mL the phase response of the acoustic mode at a frequency of 42.7 MHz has a linear form, and its maximum change is 55°. The maximum change in the insertion loss for this mode was 18 dB for a glucose concentration in the working solution of 0.4 mg/mL. The range of glucose concentrations measured using this method, from 0 to 0.9 mg/mL, corresponds to the corresponding range in the blood. The possibility of changing the conductivity range of a glucose solution depending on the concentration of the GOx enzyme in the LB film will make it possible to develop glucose sensors for higher concentrations. Such technological sensors would be in demand in the food and pharmaceutical industries. The developed technology can become the basis for creating a new generation of acoustoelectronic biosensors in the case of using other enzymatic reactions.

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

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

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

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

Disruption of the Molecular Regulation of Mitochondrial Metabolism in Airway and Lung Epithelial Cells by Cigarette Smoke: Are Aldehydes the Culprit?

Chronic obstructive pulmonary disease (COPD) is a devastating lung disease for which cigarette smoking is the main risk factor. Acetaldehyde, acrolein, and formaldehyde are short-chain aldehydes known to be formed during pyrolysis and combustion of tobacco and have been linked to respiratory toxicity. Mitochondrial dysfunction is suggested to be mechanistically and causally involved in the pathogenesis of smoking-associated lung diseases such as COPD. Cigarette smoke (CS) has been shown to impair the molecular regulation of mitochondrial metabolism and content in epithelial cells of the airways and lungs. Although it is unknown which specific chemicals present in CS are responsible for this, it has been suggested that aldehydes may be involved. Therefore, it has been proposed by the World Health Organization to regulate aldehydes in commercially-available cigarettes. In this review, we comprehensively describe and discuss the impact of acetaldehyde, acrolein, and formaldehyde on mitochondrial function and content and the molecular pathways controlling this (biogenesis versus mitophagy) in epithelial cells of the airways and lungs. In addition, potential therapeutic applications targeting (aldehyde-induced) mitochondrial dysfunction, as well as regulatory implications, and the necessary required future studies to provide scientific support for this regulation, have been covered in this review.

Chemosensory Contributions of E-Cigarette Additives on Nicotine Use

While rates of smoking combustible cigarettes in the United States have trended down in recent years, use of electronic cigarettes (e-cigarettes) has dramatically increased, especially among adolescents. The vast majority of e-cigarette users consume "flavored" products that contain a variety of chemosensory-rich additives, and recent literature suggests that these additives have led to the current "teen vaping epidemic." This review, covering research from both human and rodent models, provides a comprehensive overview of the sensory implications of e-cigarette additives and what is currently known about their impact on nicotine use. In doing so, we specifically address the oronasal sensory contributions of e-cigarette additives. Finally, we summarize the existing gaps in the field and highlight future directions needed to better understand the powerful influence of these additives on nicotine use.

Association of Mixed Use of Electronic and Conventional Cigarettes and Exposure to Secondhand Smoke With Prediabetes

CONTEXT

Despite previous studies regarding the association between smoking and diabetes, the effects of electronic cigarettes and secondhand smoke (SHS) on glucose metabolism and insulin sensitivity have not been fully elucidated.

OBJECTIVE

To examine the association of mixed electronic and conventional cigarette use and exposure to SHS with prediabetes.

DESIGN

Data from the 2014-2018 Korean National Health and Nutrition Examination Survey were analyzed.

SETTING

Nationwide population-based.

PARTICIPANTS

Of 39 199 participants, 22 385 participants (9490 men, 12 895 women) without diabetes were included. The main independent variables were smoking behaviors, including exposure to SHS.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Prediabetes (hemoglobin A1C of 5.7-6.4%).

RESULTS

Of 22 385 participants without diabetes, 6735 had prediabetes. Mixed cigarette use was associated with a 1.57-fold increase in the odds of prediabetes when compared with never-smoking [odds ratio (OR) = 1.57, 95% CI = 1.29-1.92] and a 1.27-fold increase when compared with conventional cigarette use only (OR = 1.27, 95% CI = 1.07-1.52). Participants who were current nonsmokers, but mixed users in the past had an increased risk of prediabetes (OR = 1.54, 95% CI = 1.04-2.13). There was no significant association between prediabetes and current nonsmoking in individuals with previous conventional cigarette use only. Among never-smokers, exposure to SHS significantly increased the risk of prediabetes (OR = 1.16, 95% CI = 1.04-1.30).

CONCLUSIONS

Mixed use of electronic and conventional cigarettes and exposure to SHS increased the risk of prediabetes. Further studies are required to comprehensively investigate the molecular biology underlying the effects of previous and current mixed use of electronic cigarettes and SHS on glucose metabolism.

A Retrospective Analysis of Chemical Constituents in Regulated and Unregulated E-Cigarette Liquids

E-cigarette or vaping use-associated lung injury (EVALI) was identified with the incidents of a multi-state outbreak of acute lung injuries associated with the use of electronic cigarettes (e-cigs) and attributed to vitamin E acetate in off-market cannabis-based e-liquids. Aside from EVALI, hypersecretion of mucus, irritated nasal passages, and watery, red eyes have been defined as complaints associated with vaping standard nicotine-based e-liquids. The chemical composition of e-liquids varies between manufacturers and robust oversight of ingredients is lacking. Manufacturers use chemicals deemed "generally recognized as safe" (GRAS) by the FDA, a designation for chemicals used in foodstuffs to be ingested. Most "GRAS" chemicals are associated with at least one Global Harmonization System (GHS) warning class, ranging from irritant to toxic. Untargeted chemical analysis is critical to evaluate e-liquid products to determine chemical composition; equally important is the quantitation of components to help elucidate the potential harms from exceeding recommended exposure limits. Untargeted screening of e-liquids was accomplished using gas chromatography-mass spectrometry (GC-MS) and Direct Analysis in Real Time-AccuTOF™ mass spectrometry (DART-ToF-MS) and has identified 350 chemical constituents from 241 products analyzed. Nicotine, caffeine, menthol, and vitamin E were confirmed and quantitated by GC-MS, ethanol was confirmed and quantitated by headspace-gas chromatography-dual flame ionization detection (HS-GC-FID), and olivetol and cannabinoids were confirmed and quantitated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Maximum identified concentrations of nicotine, caffeine, menthol, vitamin E, ethanol, olivetol, Δ9-tetrahydrocannabinol, and cannabidiol were 56.4, 26.9, 4.28, 307.9, 217.2, 399.6, 497.7, and 332.6 mg/ml, respectively. Evaluation of untargeted analysis and quantitation of unlabeled chemical components of e-liquids is essential to improving etiology of acute lung injury and less severe impacts of vaping, both short-term and long-term. The historical documentation of unlabeled ingredients can provide some insight for a retrospective analysis of health consequences and inform policy discussions.

Diacetyl and Other Ketones in e-Cigarette Aerosols: Some Important Sources and Contributing Factors

Background: Concerns over the presence of the diketones 2,4 butanedione (DA) and 2,3 pentanedione (AP) in e-cigarettes arise from their potential to cause respiratory diseases. Their presence in e-liquids is a primary source, but they may potentially be generated by glycerol (VG) and propylene glycol (PG) when heated to produce aerosols. Factors leading to the presence of AP, DA and acetoin (AC) in e-cigarette aerosols were investigated. We quantified direct transfer from e-liquids, examined thermal degradation of major e-liquid constituents VG, PG and 1,3 propanediol (1,3 PD) and the potential for AC, AP and DA production from sugars and flavor additives when heated in e-cigarettes.

Method: Transfers of AC, AP and DA from e-liquids to e-cigarette aerosols were quantified by comparing aerosol concentrations to e-liquid concentrations. Thermal generation from VG, PG or 1,3 PD e-liquids was investigated by measuring AC, AP and DA emissions as a function of temperature in an e-cigarette. Thermal generation of AC, AP and DA from sugars was examined by aerosolising e-liquids containing sucrose, fructose or glucose in an e-cigarette. Pyrolytic formation of AP and DA from a range of common flavors was assessed using flash pyrolysis techniques.

Results: AC transfer efficiency was >90%, while AP and DA were transferred less efficiently (65%) indicating losses during aerosolisation. Quantifiable levels of DA were generated from VG and PG, and to a lesser extent 1,3 PD at coil temperatures >300°C. Above 350°C AP was generated from VG and 1,3 PD but not PG. AC was not generated from major constituents, although low levels were generated by thermal reduction of DA. Aerosols from e-liquids containing sucrose contained quantifiable (>6 ng/puff) levels of DA at all sucrose concentrations tested, with DA emissions increasing with increasing device power and concentration. 1% glucose, fructose or sucrose e-liquids gave comparable DA emissions. Furanose ring compounds also generate DA and AP when heated to 250°C.

Conclusions: In addition to less than quantitative direct transfer from the e-liquid, DA and AP can be present in the e-cigarette aerosol due to thermal decomposition reactions of glycols, sugars and furanonse ring flavors under e-cigarette operating conditions.

Characterization of Electronic Cigarette Warning Statements Portrayed in YouTube Videos

INTRODUCTION

In 2018, the United States Food and Drug Administration (FDA) required that electronic cigarette (e-cigarette) manufacturers, packagers, importers, distributors, and retailers display an addictive or alternate warning statement on e-cigarette visual advertisements. Few studies have investigated the FDA-mandated and other warnings on social media. This study examined the prevalence and content of warning statements in e-cigarette-related YouTube videos.

METHODS

In 2019, The Virginia Commonwealth University Center for the Study of Tobacco Products conducted bi-monthly (February-June) YouTube searches by relevance and view count to identify e-cigarette-related videos. Overall, 178 videos met the inclusion criteria. Staff coded each video for the presence of a visual/verbal warning statement, warning statement type (eg, FDA-mandated, addiction/tobacco, safety/toxic exposure, health effects), sponsorship, and tobacco product characteristics. A data extraction tool collected the video URL, title, upload date, and number of views, likes/dislikes, and comments.

RESULTS

Only 5.1% of videos contained FDA-mandated and 21.9% contained non-mandated warnings. All videos with FDA-mandated and 46.2% of non-mandated warnings were represented visually. Only 13.1% of industry-sponsored videos uploaded after the mandate effective date had an FDA-mandated warning statement and videos with FDA-mandated and non-mandated (v. no) warnings had significantly fewer views, likes, dislikes, and comments. Among all non-mandated warnings, 31.3% featured an addiction/tobacco, 18.8% a safety/toxic exposure, and 37.5% a health effects warning.

CONCLUSIONS

The prevalence of FDA-mandated warning statements in e-cigarette related YouTube videos was low. FDA enforcement of the warning statement mandate on YouTube could increase the public's understanding of the addictive nature of nicotine in e-cigarettes.

IMPLICATIONS

The FDA has the authority to regulate the advertisement and promotion of e-cigarettes on the Internet. These data can inform future FDA requirements related to the language content and visual representation of addiction/tobacco, safety/exposure, and health effects warning statements that appear in YouTube videos and other visual social media popular among young people. Such data would help consumers make informed decisions about purchasing e-cigarette products, using e-cigarettes, and avoiding unintentional harm related to e-cigarettes. In addition, these data may help social media platforms make decisions on whether they will prohibit advertisements that promote or facilitate the sale of tobacco products.

Association between vaping and untreated caries: A cross-sectional study of National Health and Nutrition Examination Survey 2017-2018 data

BACKGROUND

With the rise in the prevalence of electronic cigarette (e-cigarette) and vaping products and the emergence of evidence indicating their cariogenic potential, it is essential to examine the association between vaping and untreated caries at a population level.

METHODS

The authors obtained data from the 2017-2018 National Health and Nutrition Examination Survey and investigated the outcome variable-untreated caries-using oral health examination data. The authors applied multiple logistic regression analyses to assess the association between untreated caries and smoking (cigarette smoking, vaping, and both) while controlling for education, race or ethnicity, income, age, sex, and time since previous dental visit.

RESULTS

A total of 4,618 participants were included in the analyses for this cross-sectional study. Participants who currently smoked e-cigarettes were more likely to have untreated caries (odds ratio, 1.69; 95% CI, 1.24 to 2.29) than those who had never smoked, when adjusted for demographic variables. Similarly, dual smokers (e-cigarette and conventional smokers) were more likely to have untreated caries compared with nondual smokers (odds ratio, 2.43; 95% CI, 1.36 to 4.36).

CONCLUSION

Both vaping and dual smoking are associated with an increased occurrence of untreated caries.

PRACTICAL IMPLICATIONS

Vaping status should be included as a part of health history questionnaires for patients. Dental professionals should be informed of the potential oral health implications of vaping and, in turn, impart this knowledge to patients.

Assessment of the potential vaping-related exposure to carbonyls and epoxides using stable isotope-labeled precursors in the e-liquid

The formation of carbonyls and epoxides in e-cigarette (EC) aerosol is possible due to heating of the liquid constituents. However, high background levels of these compounds have inhibited a clear assessment of exposure during use of ECs. An EC containing an e-liquid replaced with 10% of ¹³C-labeled propylene glycol and glycerol was used in a controlled use clinical study with 20 EC users. In addition, five smokers smoked cigarettes spiked with the described e-liquid. Seven carbonyls (formaldehyde, acetaldehyde, acrolein, acetone, crotonaldehyde, methacrolein, propionaldehyde) were measured in the aerosol and the mainstream smoke. Corresponding biomarkers of exposure were determined in the user’s urine samples. ¹³C-labeled formaldehyde, acetaldehyde and acrolein were found in EC aerosol, while all seven labeled carbonyls were detected in smoke. The labeled biomarkers of exposure to formaldehyde (¹³C-thiazolidine carboxylic acid and ¹³C-N-(1,3-thiazolidine-4-carbonyl)glycine), acrolein (¹³C₃-3-hydroxypropylmercapturic acid) and glycidol (¹³C₃-dihydroxypropylmercapturic acid) were present in the urine of vapers indicating an EC use-specific exposure to these toxicants. However, other sources than vaping contribute to a much higher extent by several orders of magnitude to the overall exposure of these toxicants. Comparing data for the native (unlabeled) and the labeled (exposure-specific) biomarkers revealed vaping as a minor source of user’s exposure to these toxicants while other carbonyls and epoxides were not detectable in the EC aerosol.

A review of nicotine-containing electronic cigarettes-Trends in use, effects, contents, labelling accuracy and detection methods

Electronic cigarettes (ECs) are thought to be less harmful than traditional combustible cigarettes and were originally intended to help smokers quit. Over the past two decades, they have especially gained popularity with the younger generation. To date, there are over 7000 unique e-liquid flavours available and over 400 different e-cigarette brands. The accuracy of nicotine strength labelling in e-liquids was assessed in this work. Twenty-three studies from around the world were chosen to assess the level and frequency of nicotine mislabelling in 545 e-liquid products. Nicotine strengths were most commonly mislabelled by between 5% and 20%, with the majority testing lower than what the label indicated. Fifteen European e-liquids that were assessed were labelled as 20 mg/ml or less, yet when tested, they contained more than 20 mg/ml of nicotine. One e-liquid that was supposed to contain no nicotine in fact contained 23.91 mg/ml of nicotine. Furthermore, the difference between the medians of the available labelled and experimental nicotine concentrations was significant (p < 0.001, Wilcoxon signed rank test). Preliminary studies show that high nicotine levels delivered via aerosol increase the risk for nicotine poisoning and cause airway inflammation. Other EC ingredients, such as flavourings, contribute to EVALI and 'popcorn lung'. There is evidence that certain flavourings, such as menthol, reinforce the effects of nicotine and modify drug absorption and metabolism. There is a global need for better quality control in EC products in order to make these safe for consumers.

Method Validation Approaches for Analysis of Constituents in ENDS

OBJECTIVE

We assessed how many peer-reviewed publications reporting chemical quantities and/or yields from electronic nicotine delivery systems (ENDS) have included adequate method validation characteristics in the publication for appropriate interpretation of data quality for informing tobacco regulatory science.

METHODS

We searched 5 databases (Web of Knowledge, PubMed, SciFinder, Embase, EBSCOhost) for ENDS publications between January 2007 and September 2018. Of the 283 publications screened, 173 publications were relevant for analysis. We identified the publications that report a certain degree of control in data quality, ie, the publications that report marginally validated methods (MVMs). MVMs refer to the methods that: (1) report 3 or more International Conference on Harmonisation (ICH) method validation characteristics, (2) state the method was validated, (3) cite their own previous publication(s) that report MVMs, or (4) use a method within the accreditation scope of an accredited laboratory.

RESULTS

Overall, 97 publications (56%) report MVMs in their studies. This percentage also reflects the publication distribution for the majority of the 28 chemicals measured by MVMs.

CONCLUSIONS

This study highlights the need for reporting sufficient validation characteristics following appropriate guidance to ensure the accuracy and reliability of the published analytical data for proper data interpretations that may support policy.

History repeats itself: Role of characterizing flavors on nicotine use and abuse

The popularity of e-cigarettes has skyrocketed in recent years, and most vapers use flavored e-cigarette products. Consumption of flavored e-cigarettes exceeds that of combustible cigarettes and other tobacco products among adolescents, who are particularly vulnerable to becoming nicotine dependent. Flavorings have been used by the tobacco industry since the 17th century, but the use of flavors by the e-cigarette industry to create products with "characterizing" flavors (i.e. flavors other than tobacco or menthol) has sparked a public health debate. This review addresses the possibility that characterizing flavors make nicotine more appealing, rewarding and addictive. It also discusses ways in which preclinical and clinical studies could improve our understanding of the mechanisms by which flavors may alter nicotine reward and reinforcement. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Alterations in Vascular Function Associated With the Use of Combustible and Electronic Cigarettes

Background Electronic cigarettes (e-cigarettes) have been proposed as a potential harm reduction tool for combustible cigarette smokers. The majority of adult e-cigarette users continue to smoke combustible cigarettes and are considered dual users. The vascular impact of e-cigarettes remains incompletely defined. Methods and Results We examined the association of e-cigarette use with measures of vascular function and tonometry, preclinical measures of cardiovascular injury. As part of the CITU (Cardiovascular Injury due to Tobacco Use) study, we performed noninvasive vascular function testing in individuals without known cardiovascular disease or cardiovascular disease risk factors who were nonsmokers (n=94), users of combustible cigarettes (n=285), users of e-cigarettes (n=36), or dual users (n=52). In unadjusted analyses, measures of arterial stiffness including carotid-femoral pulse wave velocity, augmentation index, carotid-radial pulse wave velocity, and central blood pressures differed across the use groups. In multivariable models adjusted for age, sex, race, and study site, combustible cigarette smokers had higher augmentation index compared with nonusers (129.8±1.5 versus 118.8±2.7, P=0.003). The augmentation index was similar between combustible cigarette smokers compared with sole e-cigarette users (129.8±1.5 versus 126.2±5.9, P=1.0) and dual users (129.8±1.5 versus 134.9±4.0, P=1.0). Endothelial cells from combustible cigarette smokers and sole e-cigarette users produced less nitric oxide in response to A23187 stimulation compared with nonsmokers, suggestive of impaired endothelial nitric oxide synthase signaling. Conclusions Our findings suggest that e-cigarette use is not associated with a more favorable vascular profile. Future longitudinal studies are needed to evaluate the long-term risks of sustained e-cigarette use.

E-cigarette use is associated with a self-reported diagnosis of prediabetes in never cigarette smokers: Results from the behavioral risk factor surveillance system survey

BACKGROUND

The use of e-cigarettes is increasing in the US but there is still a paucity of research on the metabolic effects of e-cigarette use. The goal of this work was to determine the association between e-cigarette use and self-reported prediabetes in adult never cigarette smokers.

METHOD

The 2017 cross sectional Behavioral Risk Factor Surveillance System (BRFSS) survey data was used for the analysis. Current e-cigarette users reported daily or someday use of e-cigarettes and former e-cigarette users reported no current use of e-cigarettes. Participants who reported a history of diabetes, gestational prediabetes/ diabetes were excluded. Odds ratios were calculated to determine the association between e-cigarette use and self-reported prediabetes in never cigarette smokers after adjusting for potential confounders.

RESULTS

There were a total of 154,404 participants that met the inclusion criteria. Of those participants, there were 143,952 never, 1339 current and 7625 former e-cigarette users. Current e-cigarette users had an increased odds of reporting a diagnosis of prediabetes 1.97 (95% CI 1.25-3.10) compared to never e-cigarette users. After stratifying by gender, men and women had an increased odds ratio of reporting a diagnosis of prediabetes 2.36 (95% CI 1.26-4.40) and 1.88 (95% CI 1.00-3.53) respectively when compared to never e-cigarette users. There was no association between former e-cigarette use and a self-reported diagnosis of prediabetes.

CONCLUSION

Our findings show that e-cigarette use may be associated with self-reported prediabetes. Further evaluation is needed in prospective studies.

Vaping patterns, nicotine dependence and reasons for vaping among American Indian dual users of cigarettes and electronic cigarettes

BACKGROUND

The American Cancer Society discourages the dual use of electronic cigarettes (ECs) and cigarettes because such use has not resulted in reduced exposures to the harmful effects of smoking. American Indian (AI) people have the highest prevalence of smoking and of EC use in the United States, but very little is known about dual EC and cigarette use in AI communities.

METHODS

In 2016, 375 adult AI in Oklahoma who smoked cigarettes completed a survey about EC use (vaping). We describe vaping patterns, nicotine dependence, and reasons for EC use among the subset of 44 (12%) current dual EC users. To differentiate habitual EC users from occasional or merely curious users, we defined dual use as using ECs on some days or every day in the past 30 days.

RESULTS

About one-third of dual users vaped ten or more times daily. About two-thirds used a tank product. Eleven percent used ECs without nicotine and another 9% were unsure of the nicotine content. A minority (40%) enjoyed vaping more than smoking, and most (76%) would smoke first on days they did both. Thirty-one percent vaped within 5 min of waking and another 24% within 30 min. Although the two-item heaviness of use index did not differ significantly between smoking and vaping, the ten-item Penn State Dependence Index (PSDI) suggested greater dependence on smoking than vaping (11.02 vs. 6.42, respectively; p < .0001). The most common reasons for vaping were to reduce smoking (79%), enjoyment of flavors (78%), and ability to vape where smoking is not allowed (73%). Perceptions of less harm to others (69%) or to self were the next most common (65%). Fewer than half used ECs to reduce stress, for affordability, or because others used them.

CONCLUSIONS

Nearly 20% of dual users used ECs either without nicotine or without knowing if the product contained nicotine. The PSDI indicated greater dependence on smoking than vaping. Reasons for vaping were nearly equal between smoking reduction and enjoying flavors. Understanding patterns of dual use will inform future efforts to address nicotine dependence for AI communities with high prevalence of smoking.

Sucralose-Enhanced Degradation of Electronic Cigarette Liquids during Vaping

Electronic cigarette liquids (e-liquids) with sweetener additives such as sucralose, a synthetic chlorinated disaccharide, are popular among some e-cigarette consumers; sucralose can be added either by the manufacturer or by the consumer. The prevalence of sucralose in commercial e-liquids is not known, nor is the typical concentration of sucralose when present; labels are not required to disclose ingredient information. Here, we report the effects of sucralose on e-liquid degradation upon e-cigarette vaping as studied using ¹H NMR spectroscopy, ion chromatography, and gas chromatography coupled with detection by mass spectrometry or flame ionization detector. Sucralose was found to be subject to degradation when included in propylene glycol + glycerol based e-liquids and vaped; the presence of sucralose in the e-liquids also resulted in altered and enhanced solvent degradation. In particular, production of aldehydes (carbonyls) and hemiacetals (which have implications for health) was enhanced, as demonstrated by ¹H NMR. The presence of sucralose at 0.03 mol % (0.14 wt %) in an e-liquid also resulted in production of potentially harmful organochlorine compounds and catalyzed the cyclization of aldehydes with solvents to acetals upon vaping; the presence of chloride in e-liquid aerosols was confirmed by ion chromatography. Quantities of sucralose as low as 0.05 mol % (0.24 wt %) in e-liquids lead to significant production of solvent degradation products.

A Public Health Crisis: Electronic Cigarettes, Vape, and JUUL

Electronic cigarettes (e-cigarettes) and vape devices have rapidly become the most common tobacco products used by youth, driven in large part by marketing and advertising by e-cigarette companies. There is substantial evidence that adolescent e-cigarette use leads to use of combustible tobacco products. E-cigarette companies commonly advertise that e-cigarettes contain nicotine, flavoring chemicals, and humectants (propylene glycol and/or vegetable glycerin), but toxicants, ultrafine particles, and carcinogens have also been found in e-cigarette solutions and emissions, many of which are known to cause adverse health effects. Most major e-cigarette brands are owned by big tobacco companies that use similar marketing and advertising strategies to attract youth users as they did with traditional tobacco products. In this review, we provide an overview of e-cigarettes and vape devices with an emphasis on the impact for the pediatric population. We describe the vast array of e-cigarette devices and solutions, concern for nicotine addiction, and the scientific background on the known health harms. There are accompanying visual depictions to assist in identifying these products, including newer e-cigarette products and JUUL. Because current federal regulations are insufficient to protect youth from e-cigarette use, exposure, and nicotine addiction, there are recommendations for pediatricians and pediatric health care providers to counsel and advocate for a tobacco-free lifestyle for patients and families.

Answering questions about electronic cigarettes using a multidisciplinary model

Electronic cigarettes (ECIGs) are a relatively new class of tobacco products and a subject of much debate for scientists and policymakers worldwide. Objective data that address the ECIG risk-benefit ratio for individual and public health are needed, and addressing this need requires a multidisciplinary approach that spans several areas of psychology as well as chemistry, toxicant inhalation, and physiology. This multidisciplinary approach would benefit from methods that are reliable, valid, and swift. For this reason, we formed a multidisciplinary team to develop methods that could answer questions about ECIGs and other potential modified risk tobacco products. Our team includes scientists with expertise in psychology (clinical, community, and experimental) and other disciplines, including aerosol research, analytical chemistry, biostatistics, engineering, internal medicine, and public health. The psychologists on our team keep other members focused on factors that influence individual behavior, and other team members keep the psychologists aware of other issues, such as product design. Critically, all team members are willing to extend their interests beyond the boundaries of their discipline to collaborate effectively with the shared goal of producing the rigorous science needed to inform empirically based tobacco policy. In addition, our trainees gain valuable knowledge from these collaborations and learn that other disciplines are accessible, exciting, and can enhance their own research. Multidisciplinary work presents challenges: learning other scientists' languages and staying focused on our core mission. Overall, our multidisciplinary team has led to several major findings that inform the scientific, regulatory, and public health communities about ECIGs and their effects. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cigarette Smoke and E-Cigarette Vapor Dysregulate Osteoblast Interaction With Titanium Dental Implant Surface

The purpose of this study was to determine the possible deleterious effects of e-cigarette vapor on osteoblast interaction with dental implant material. Osteoblasts were cultured onto Ti6Al4V titanium implant disks and were then exposed or not to whole cigarette smoke (CS), as well as to nicotine-rich (NR) or nicotine-free (NF) e-vapor for 15 or 30 minutes once a day for 1, 2, or 3 days, after which time various analyses were performed. Osteoblast growth on the titanium implant disks was found to be significantly (P &lt; .001) reduced following exposure to CS and to the NR and NF e-vapors. Osteoblast attachment to the dental implant material was also dysregulated by CS and the NR and NF e-vapors through a decreased production of adhesion proteins such as F-actin. The effects of CS and e-cigarette vapor on osteoblast growth and attachment were confirmed by reduced alkaline phosphatase (ALP) activity and tissue mineralization. The adverse effects of CS and the NR and NF e-vapors on osteoblast interaction with dental implant material also involved the caspase-3 pathway, as the caspase-3 protein level increased following exposure of the osteoblasts to CS or e-vapor. It should be noted that the adverse effects of CS on osteoblast growth, attachment, ALP, and mineralized degradation were greater than those of the NR and NF e-vapors, although the latter did downregulate osteoblast interaction with the dental implant material. Overall results suggest the need to consider e-cigarettes as a possible contributor to dental implant failure and/or complications.

Toxic emissions resulting from sucralose added to electronic cigarette liquids

Electronic cigarettes (ECIGs) are appealing in part because of the many flavors of the liquids used in them. Concerns have been raised that some ECIG liquid flavors, especially those that are sweet, are attracting otherwise nicotine-naïve youth to ECIGs. Sucralose is an artificial, non-caloric sweetener that is added to some ECIG liquids. In this study, we evaluated the toxicants, namely isomers of chloropropanols that can be produced when sucralose-containing ECIG liquid is aerosolized. An analytical separation method relying on solid-phase extraction (SPE) to isolate chloropropanols from the propylene glycol/glycerol matrix was developed. Chloropropanols were then derivatized by silylation before they were analyzed on GC-MS. The influence of different ECIG operating conditions on the generation of chloropropanols was studied by varying ECIG device design and power output and also the sucralose concentration of the liquid. Heated sucralose-containing ECIG liquids produce two toxic compounds that can be found in the resulting aerosols. The two chloropropanols, 3-monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) that were detected under all conditions were found to be correlated significantly with liquid sucralose content. Effective regulation of ECIGs will minimize user and bystander exposure to these and other ECIG toxicants.

Environmental Aldehyde Sources and the Health Implications of Exposure

Aldehydes, which are present within the air as well as food and beverage sources, are highly reactive molecules that can be cytotoxic, mutagenic, and carcinogenic. To prevent harm from reactive aldehyde exposure, the enzyme aldehyde dehydrogenase 2 (ALDH2) metabolizes reactive aldehydes to a less toxic form. However, the genetic variant of ALDH2, ALDH2*2, significantly reduces the ability to metabolize reactive aldehydes in humans. Therefore, frequent environmental aldehyde exposure, coupled with inefficient aldehyde metabolism, could potentially lead to an increased health risk for diseases such as cancer or cardiovascular disease.Here, we discuss the environmental sources of reactive aldehydes and the potential health implications particularly for those with an ALDH2*2 genetic variant. We also suggest when considering the ALDH2*2 genetic variant the safety limits of reactive aldehyde exposure may have to be reevaluated. Moreover, the ALDH2*2 genetic variant can also be used as an example for how to implement precision medicine in the field of environmental health sciences.