Key issues surrounding the health impacts of electronic nicotine delivery systems (ENDS) and other sources of nicotine

Answer questions and earn CME/CNE Over the last decade, the use of electronic nicotine delivery systems (ENDS), including the electronic cigarette or e-cigarette, has grown rapidly. More youth now use ENDS than any tobacco product. This extensive research review shows that there are scientifically sound, sometimes competing arguments about ENDS that are not immediately and/or completely resolvable. However, the preponderance of the scientific evidence to date suggests that current-generation ENDS products are demonstrably less harmful than combustible tobacco products such as conventional cigarettes in several key ways, including by generating far lower levels of carcinogens and other toxic compounds than combustible products or those that contain tobacco. To place ENDS in context, the authors begin by reviewing the trends in use of major nicotine-containing products. Because nicotine is the common core-and highly addictive-constituent across all tobacco products, its toxicology is examined. With its long history as the only nicotine product widely accepted as being relatively safe, nicotine-replacement therapy (NRT) is also examined. A section is also included that examines snus, the most debated potential harm-reduction product before ENDS. Between discussions of NRT and snus, ENDS are extensively examined: what they are, knowledge about their level of "harm," their relationship to smoking cessation, the so-called gateway effect, and dual use/poly-use. CA Cancer J Clin 2017;67:449-471. © 2017 American Cancer Society.

Minimum Age of Sale for Tobacco Products and Electronic Cigarettes: Ethical Acceptability of US "Tobacco 21 Laws"

Several US jurisdictions have recently passed laws that raise the minimum age of sale for tobacco products and electronic cigarettes to 21 years (Tobacco 21 laws). Although these laws have been demonstrated to be an effective means to reduce youth smoking initiation, their passage and potential expansion have provoked controversy. Critics have objected to these laws, claiming that they unduly intrude on individual freedom and that they irrationally and paternalistically restrict the freedom of those aged 18 to 20 years, who were previously able to legally purchase tobacco products. We have examined the ethical acceptability of Tobacco 21 laws. First, we have described ethical support for such a restriction grounded in its public health benefit. We have then offered arguments that raise doubts about the soundness of critics' objections to these regulations and described an additional ethical justification arising from concern about preventing harm to others. On the basis of this analysis, we conclude that Tobacco 21 laws are ethically justifiable.

Flavored e-cigarette liquids and cinnamaldehyde impair respiratory innate immune cell function

Innate immune cells of the respiratory tract are the first line of defense against pathogenic and environmental insults. Failure of these cells to perform their immune functions leaves the host susceptible to infection and may contribute to impaired resolution of inflammation. While combustible tobacco cigarettes have been shown to suppress respiratory immune cell function, the effects of flavored electronic cigarette liquids (e-liquids) and individual flavoring agents on respiratory immune cell responses are unknown. We investigated the effects of seven flavored nicotine-free e-liquids on primary human alveolar macrophages, neutrophils, and natural killer (NK) cells. Cells were challenged with a range of e-liquid dilutions and assayed for their functional responses to pathogenic stimuli. End points included phagocytic capacity (neutrophils and macrophages), neutrophil extracellular trap formation, proinflammatory cytokine production, and cell-mediated cytotoxic response (NK cells). E-liquids were then analyzed via mass spectrometry to identify individual flavoring components. Three cinnamaldehyde-containing e-liquids exhibited dose-dependent broadly immunosuppressive effects. Quantitative mass spectrometry was used to determine concentrations of cinnamaldehyde in each of the three e-liquids, and cells were subsequently challenged with a range of cinnamaldehyde concentrations. Cinnamaldehyde alone recapitulated the impaired function observed with e-liquid exposures, and cinnamaldehyde-induced suppression of macrophage phagocytosis was reversed by addition of the small-molecule reducing agent 1,4-dithiothreitol. We conclude that cinnamaldehyde has the potential to impair respiratory immune cell function, illustrating an immediate need for further toxicological evaluation of chemical flavoring agents to inform regulation governing their use in e-liquid formulations.

Pulmonary toxicity of e-cigarettes

Electronic cigarettes (e-cigarettes or e-cigs) are designed to heat and aerosolize mixtures of vegetable glycerin, propylene glycol, nicotine, and flavoring additives, thus delivering nicotine by inhalation in the absence of combustion. These devices were originally developed to facilitate smoking cessation and have been available in the United States for over a decade. Since 2010, e-cig use has expanded rapidly, especially among adolescents, despite a paucity of short- and long-term safety data. Patterns of use have shifted to include never smokers and many dual users of e-cigs and combustible tobacco products. Over the last several years, research into the potential toxicities of e-cig aerosols has grown exponentially. In the interim, regulatory policymakers across the world have struggled with how to regulate an increasingly diverse array of suppliers and products, against a backdrop of strong advocacy from users, manufacturers, and tobacco control experts. Herein we provide an updated review of the pulmonary toxicity profile of these devices, summarizing evidence from cell culture, animal models, and human subjects. We highlight the major gaps in our current understanding, emphasize the challenges confronting the scientific and regulatory communities, and identify areas that require more research in this important and rapidly evolving field.

The association between electronic-cigarette use and self-reported oral symptoms including cracked or broken teeth and tongue and/or inside-cheek pain among adolescents: A cross-sectional study

Background

Little is known about oral health related to electronic-cigarette (EC) use, even though EC use is increasing rapidly. The aim of this study is to assess the relationship between EC use and oral health, including ‘gingival pain and/or bleeding’, ‘tongue and/or inside-cheek pain’, and ‘cracked or broken teeth’ among adolescents.

Methods

A total of 65,528 students in 2016 were included in this cross-sectional study.

Results

For EC use, 0.5% (n = 297) students were daily users, 1.9% (n = 1259) were ‘1 to 29 days past month users’, and 5.9% (n = 3848) were former users. Overall, 18.5% students reported they had experienced ‘gingival pain and/or bleeding’, 11.0% reported ‘tongue and/or inside-cheek pain’, and 11.4% reported a ‘cracked or broken tooth’ within the past 12 months. When comparing ‘daily EC users’, ‘1 to 29 days past month EC users’, and ‘former EC users’ with ‘never EC users’, the adjusted ORs for ‘cracked or broken tooth’ were 1.65 (95% CI: 1.19–2.27), 1.26 (95% CI: 1.06–1.51), and 1.16 (95% CI: 1.04–1.30), respectively. Comparing ‘daily EC users’ with ‘never EC users’, the adjusted OR for ‘tongue and/or inside-cheek pain’ was 1.54 (1.05–2.26). However, EC use among adolescents was not associated with ‘gingival pain and/or bleeding’ when adjusted for the potential confounders.

Conclusions

Based on the results, the odds of cracked or broken teeth among daily, ‘1 to 29 days past month’, and former EC users were significantly higher than those among never EC users. The odds of tongue and/or inside-cheek pain among daily EC users were significantly higher than those among never EC users. In conclusion, the results suggest that daily EC use among adolescents may be a risk factor for cracked or broken teeth and tongue and/or inside-cheek pain.

[Do electronic cigarettes increase the risk of smoking among adolescents and young adults?]

Introduction: Electronic cigarette use is significantly higher among 15-24-year-olds than in other age-groups. Electronic cigarettes, which may contain nicotine, could be a gateway to smoking initiation among young people. In this article, we reviewed the literature on smoking initiation or smoking enhancement by the use of e-cigarettes. Methods: We carried out a qualitative analysis in January 2016. We selected all longitudinal studies among adolescents or young adults using electronic cigarettes. Results: The analysis focused on 5 of the 544 articles identified, corresponding to five prospective observational studies. Four studies concluded that e-cigarette use was statistically associated with a high risk of smoking initiation. Young vapers were 8.3 (95% CI = 1.-58.6) to 12.7 (95% CI = 4.0-40.3) times more likely to initiate smoking at 1 year than non-vapers. Previous exposure to electronic cigarettes increased the risk of smoking conventional cigarettes by 14-year-old adolescents by 75% at 1 year follow-up. Conclusion: Trying e-cigarettes during adolescence or young adulthood may have contributed to starting and continuation of smoking. However, these results must be interpreted cautiously due to methodological weaknesses.

Comparative tumor promotion assessment of e-cigarette and cigarettes using the in vitro Bhas 42 cell transformation assay

In vitro cell transformation assays (CTA) are used to assess the carcinogenic potential of chemicals and complex mixtures and can detect nongenotoxic as well as genotoxic carcinogens. The Bhas 42 CTA has been developed with both initiation and promotion protocols to distinguish between these two carcinogen classes. Cigarette smoke is known to be carcinogenic and is positive in in vitro genotoxicity assays. Cigarette smoke also contains nongenotoxic carcinogens and is a tumour promoter and cocarcinogen in vivo. We have combined a suite of in vitro assays to compare the relative biological effects of new categories of tobacco and nicotine products with traditional cigarettes. The Bhas promotion assay has been included in this test battery to provide an in vitro surrogate for detecting tumor promoters. The activity of an electronic cigarette (e-cigarette; Vype ePen) was compared to that of a reference cigarette (3R4F) in the promotion assay, using total particulate matter (TPM)/aerosol collected matter (ACM) and aqueous extracts (AqE) of product aerosol emissions. 3R4F TPM was positive in this assay at concentrations ≥6 µg/mL, while e-cigarette ACM did not have any promoter activity. AqE was found to be a lesssuitable test matrix in this assay due to high cytotoxicity. This is the first study to use the Bhas assay to compare tobacco and nicotine products and demonstrates the potential for its future application as part of a product assessment framework. These data add to growing evidence suggesting that e-cigarettes may provide a safer alternative to traditional cigarettes. Environ. Mol. Mutagen. 58:190-198, 2017. © 2017 Wiley Periodicals, Inc.

A Comparative Health Risk Assessment of Electronic Cigarettes and Conventional Cigarettes

Background: Although some studies have identified hazardous substances in electronic cigarette (EC) liquids and emissions, there is limited information about the health risks of using ECs. Methods: In this study, the U.S. Environmental Protection Agency (EPA) health risk assessment model and findings of a literature review were used to determine and profile hazards. Focus was put on the toxicants reported in the literature on conventional cigarette (CC) smoke that most strongly associated with adverse health effects. To evaluate their health risks, dose-response relationships and standard-use conditions were used to estimate average hazard exposures and to calculate the overall health risks of ECs and CCs, benchmarked against international guideline levels for each hazard. Results: Four hazards (acrolein, diethylene glycol, propylene glycol and cadmium) reported in EC emissions and seven hazards (acetaldehyde, acrolein, formaldehyde, cadmium, CO, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N'-nitrosonornicotine (NNN)) reported in CC emissions had maximum exposure levels higher than the guideline levels. Two hazards (acrolein, propylene glycol) in EC emissions and five hazards (acetaldehyde, acrolein, formaldehyde, cadmium, NNN) in CC emissions had average exposure levels higher than the guideline levels. Conclusions: Based on the conditions of use, ECs should be a safer nicotine-delivery product than CCs.

Subjective experiences at first use of cigarette, e-cigarettes, hookah, and cigar products among Texas adolescents

INTRODUCTION

Subjective experiences ("SEs") at first cigarette use have been thoroughly examined; however, limited research has examined SEs at first use of non-cigarette products. This study addresses this gap in the literature.

METHODS

Cross-sectional data from 6th, 8th and 10th grade students in four metropolitan areas of Texas (n=3907/N=461,069). Nausea, coughing, relaxation, rush/buzz, and dizziness at first use were assessed for cigarettes, e-cigarettes, hookah, and cigar products. Chi-square analyses examined differences in the prevalence of first use SEs by product. Weighted multiple logistic regression analyses examined the association of SEs and current product use. Covariates were grade, gender, race/ethnicity, and current other tobacco product use.

RESULTS

Exploratory factor analysis of SEs determined differing factor structures across tobacco products. For example, the following items loaded onto the positive SE factor: 1) relaxation, rush, and dizziness for cigarettes, and 2) relaxation and rush for e-cigarettes, hookah, and cigar products. Prevalence of negative SEs (coughing and nausea) were higher for cigarette and cigar products compared to e-cigarettes and hookah. Positive SEs for cigarettes were associated with increased odds of current cigarette use (AOR=1.51); similarly positive SEs for cigars were associated with increased odds of current cigar use (AOR=2.11). Feeling nauseous at first use of cigars was associated with decreased odds of current cigar use (AOR=0.18). No SEs were associated with current e-cigarette or hookah use.

CONCLUSIONS

Subjective experiences at first use differ by tobacco product. Longitudinal studies are needed to examine temporal relationships between SEs at first use and sustained tobacco use.

Electronic cigarettes: what are they and what do they do?

Electronic cigarettes (ECIGs) use electricity to power a heating element that aerosolizes a liquid containing solvents, flavorants, and the dependence-producing drug nicotine for user inhalation. ECIGs have evolved rapidly in the past 8 years, and the changes in product design and liquid constituents affect the resulting toxicant yield in the aerosol and delivery to the user. This rapid evolution has been accompanied by dramatic increases in ECIG use prevalence in many countries among adults and, especially, adolescents in the United States. The increased prevalence of ECIGs that deliver nicotine and other toxicants to users' lungs drives a rapidly growing research effort. This review highlights the most recent information regarding the design of ECIGs and their liquid and aerosol constituents, the epidemiology of ECIG use among adolescents and adults (including correlates of ECIG use), and preclinical and clinical research regarding ECIG effects. The current literature suggests a strong rationale for an empirical regulatory approach toward ECIGs that balances any potential ECIG-mediated decreases in health risks for smokers who use them as substitutes for tobacco cigarettes against any increased risks for nonsmokers who may be attracted to them.

A Risk Assessment Matrix for Public Health Principles: The Case for E-Cigarettes

Besides nicotine replacement therapies, a realistic alternative for smoking cessation or for smoking substitution may come from electronic cigarettes (ECs), whose popularity has been steadily growing. As for any emerging behaviour associated with exposure to inhalational agents, there is legitimate cause for concern and many health organizations and policy makers have pushed for restrictive policy measures ranging from complete bans to tight regulations of these products. Nonetheless, it is important to reframe these concerns in context of the well-known harm caused by cigarette smoking. In this article, we discuss key public health principles that should be considered when regulating ECs. These include the concept of tobacco harm reduction, importance of relative risk and risk continuum, renormalization of smoking, availability of low-risk product, proportionate taxation, and reassessment of the role of non-tobacco flavours. These public health principles may be systematically scrutinized using a risk assessment matrix that allows: (1) to determine the measure of certainty that a risk will occur; and (2) to estimate the impact of such a risk on public health. Consequently, the ultimate goal of responsible ECs regulation should be that of maximizing the favourable impact of these reduced-risk products whilst minimizing further any potential risks. Consumer perspectives, sound EC research, continuous post-marketing surveillance and reasonable safety and quality product standards should be at the very heart of future regulatory schemes that will address concerns while minimizing unintended consequences of ill-informed regulation.

Nicotine, Carcinogen, and Toxin Exposure in Long-Term E-Cigarette and Nicotine Replacement Therapy Users: A Cross-sectional Study

BACKGROUND

Given the rapid increase in the popularity of e-cigarettes and the paucity of associated longitudinal health-related data, the need to assess the potential risks of long-term use is essential.

OBJECTIVE

To compare exposure to nicotine, tobacco-related carcinogens, and toxins among smokers of combustible cigarettes only, former smokers with long-term e-cigarette use only, former smokers with long-term nicotine replacement therapy (NRT) use only, long-term dual users of both combustible cigarettes and e-cigarettes, and long-term users of both combustible cigarettes and NRT.

DESIGN

Cross-sectional study.

SETTING

United Kingdom.

PARTICIPANTS

The following 5 groups were purposively recruited: combustible cigarette-only users, former smokers with long-term (≥6 months) e-cigarette-only or NRT-only use, and long-term dual combustible cigarette-e-cigarette or combustible cigarette-NRT users (n = 36 to 37 per group; total n = 181).

MEASUREMENTS

Sociodemographic and smoking characteristics were assessed. Participants provided urine and saliva samples and were analyzed for biomarkers of nicotine, tobacco-specific N-nitrosamines (TSNAs), and volatile organic compounds (VOCs).

RESULTS

After confounders were controlled for, no clear between-group differences in salivary or urinary biomarkers of nicotine intake were found. The e-cigarette-only and NRT-only users had significantly lower metabolite levels for TSNAs (including the carcinogenic metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL]) and VOCs (including metabolites of the toxins acrolein; acrylamide; acrylonitrile; 1,3-butadiene; and ethylene oxide) than combustible cigarette-only, dual combustible cigarette-e-cigarette, or dual combustible cigarette-NRT users. The e-cigarette-only users had significantly lower NNAL levels than all other groups. Combustible cigarette-only, dual combustible cigarette-NRT, and dual combustible cigarette-e-cigarette users had largely similar levels of TSNA and VOC metabolites.

LIMITATION

Cross-sectional design with self-selected sample.

CONCLUSION

Former smokers with long-term e-cigarette-only or NRT-only use may obtain roughly similar levels of nicotine compared with smokers of combustible cigarettes only, but results varied. Long-term NRT-only and e-cigarette-only use, but not dual use of NRTs or e-cigarettes with combustible cigarettes, is associated with substantially reduced levels of measured carcinogens and toxins relative to smoking only combustible cigarettes.

PRIMARY FUNDING SOURCE

Cancer Research UK.

E-Cigarettes-What a Practicing Cardiologist Needs to Know

Cardiologists and other physicians caring for patients who either smoke tobacco or are potential or active users of E-cigarettes have many questions about this increasingly popular method for delivering nicotine to the brain: (1) What are E-cigarettes? (2) What harm do E-cigarettes pose to users and bystanders? (3) Can E-cigarettes help tobacco smokers quit? (4) Are E-cigarettes a gateway to tobacco smoking, addicting new users, particularly the young, to nicotine? and (5) Should E-cigarettes be tolerated, or even favored over tobacco, as a less harmful substitute for those unable to stop smoking tobacco? This editorial summarizes evidence and expert opinion, preparing the physician for informed discussion of this controversial subject with their patients and colleagues. Although E-cigarettes may be less harmful than tobacco cigarettes, they are definitely not harmless. Particularly concerning are the well-financed commercial interests marketing E-cigarettes to our youth. As new regulatory policies are developed, we must not allow E-cigarettes to reverse our progress in reducing tobacco smoking, the leading cause of preventable death in the United States.

Adolescent Risk Behaviors and Use of Electronic Vapor Products and Cigarettes

BACKGROUND

Adolescent use of tobacco in any form is unsafe; yet the use of electronic cigarettes and other electronic vapor products (EVPs) has increased in recent years among this age group. We assessed the prevalence and frequency of cigarette smoking and EVP use among high school students, and associations between health-risk behaviors and both cigarette smoking and EVP use.

METHODS

We used 2015 national Youth Risk Behavior Survey data (N = 15 624) to classify students into 4 mutually exclusive categories of smoking and EVP use based on 30-day use: nonuse, cigarette smoking only, EVP use only, and dual use. Prevalence of cigarette smoking and EVP use were assessed overall and by student demographics and frequency of use. Prevalence ratios were calculated to identify associations with health risk-behaviors.

RESULTS

In 2015, 73.5% of high school students did not smoke cigarettes or use EVPs, 3.2% smoked cigarettes only, 15.8% used EVPs only, and 7.5% were dual users. Frequency of cigarette smoking and EVP use was greater among dual users than cigarette-only smokers and EVP-only users. Cigarette-only smokers, EVP-only users, and dual users were more likely than nonusers to engage in several injury, violence, and substance use behaviors; have ≥4 lifetime sexual partners; be currently sexually active; and drink soda ≥3 times/day. Only dual users were more likely than nonusers not to use a condom at last sexual intercourse.

CONCLUSIONS

EVP use, alone and concurrent with cigarette smoking, is associated with health-risk behaviors among high school students.

Exposure to Nicotine and Selected Toxicants in Cigarette Smokers Who Switched to Electronic Cigarettes: A Longitudinal Within-Subjects Observational Study

INTRODUCTION

Electronic cigarettes (e-cigarettes) are purported to deliver nicotine aerosol without any toxic combustion products present in tobacco smoke. In this longitudinal within-subjects observational study, we evaluated the effects of e-cigarettes on nicotine delivery and exposure to selected carcinogens and toxicants.

METHODS

We measured seven nicotine metabolites and 17 tobacco smoke exposure biomarkers in the urine samples of 20 smokers collected before and after switching to pen-style M201 e-cigarettes for 2 weeks. Biomarkers were metabolites of 13 major carcinogens and toxicants in cigarette smoke: one tobacco-specific nitrosamine (NNK), eight volatile organic compounds (1,3-butadiene, crotonaldehyde, acrolein, benzene, acrylamide, acrylonitrile, ethylene oxide, and propylene oxide), and four polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, and pyrene). Changes in urine biomarkers concentration were tested using repeated measures analysis of variance.

RESULTS

In total, 45% of participants reported complete abstinence from cigarette smoking at 2 weeks, while 55% reported continued smoking. Levels of total nicotine and some polycyclic aromatic hydrocarbon metabolites did not change after switching from tobacco to e-cigarettes. All other biomarkers significantly decreased after 1 week of using e-cigarettes (p < .05). After 1 week, the greatest percentage reductions in biomarkers levels were observed for metabolites of 1,3-butadiene, benzene, and acrylonitrile. Total NNAL, a metabolite of NNK, declined by 57% and 64% after 1 and 2 weeks, respectively, while 3-hydroxyfluorene levels declined by 46% at week 1, and 34% at week 2.

CONCLUSIONS

After switching from tobacco to e-cigarettes, nicotine exposure remains unchanged, while exposure to selected carcinogens and toxicants is substantially reduced.

IMPLICATIONS

To our knowledge, this is the first study that demonstrates that substituting tobacco cigarettes with an e-cigarette may reduce user exposure to numerous toxicants and carcinogens otherwise present in tobacco cigarettes. Data on reduced exposure to harmful constituents that are present in tobacco cigarettes and e-cigarettes can aid in evaluating e-cigarettes as a potential harm reduction device.

A Device-Independent Evaluation of Carbonyl Emissions from Heated Electronic Cigarette Solvents

Objectives

To investigate how the two main electronic (e-) cigarette solvents—propylene glycol (PG) and glycerol (GL)—modulate the formation of toxic volatile carbonyl compounds under precisely controlled temperatures in the absence of nicotine and flavor additives.

Methods

PG, GL, PG:GL = 1:1 (wt/wt) mixture, and two commercial e-cigarette liquids were vaporized in a stainless steel, tubular reactor in flowing air ranging up to 318°C to simulate e-cigarette vaping. Aerosols were collected and analyzed to quantify the amount of volatile carbonyls produced with each of the five e-liquids.

Results

Significant amounts of formaldehyde and acetaldehyde were detected at reactor temperatures ≥215°C for both PG and GL. Acrolein was observed only in e-liquids containing GL when reactor temperatures exceeded 270°C. At 318°C, 2.03±0.80 μg of formaldehyde, 2.35±0.87 μg of acetaldehyde, and a trace amount of acetone were generated per milligram of PG; at the same temperature, 21.1±3.80 μg of formaldehyde, 2.40±0.99 μg of acetaldehyde, and 0.80±0.50 μg of acrolein were detected per milligram of GL.

Conclusions

We developed a device-independent test method to investigate carbonyl emissions from different e-cigarette liquids under precisely controlled temperatures. PG and GL were identified to be the main sources of toxic carbonyl compounds from e-cigarette use. GL produced much more formaldehyde than PG. Besides formaldehyde and acetaldehyde, measurable amounts of acrolein were also detected at ≥270°C but only when GL was present in the e-liquid. At 215°C, the estimated daily exposure to formaldehyde from e-cigarettes, exceeded United States Environmental Protection Agency (USEPA) and California Office of Environmental Health Hazard Assessment (OEHHA) acceptable limits, which emphasized the need to further examine the potential cancer and non-cancer health risks associated with e-cigarette use.

Nicotine and Tobacco as Substances of Abuse in Children and Adolescents

Nicotine is the primary pharmacologic component of tobacco, and users of tobacco products seek out its effects. The highly addictive nature of nicotine is responsible for its widespread use and difficulty with quitting. This technical report focuses on nicotine and discusses the stages of use in progression to dependence on nicotine-containing products; the physiologic characteristics, neurobiology, metabolism, pharmacogenetics, and health effects of nicotine; and acute nicotine toxicity. Finally, some newer approaches to cessation are noted.

US Adults' Perceptions of the Harmful Effects During Pregnancy of Using Electronic Vapor Products Versus Smoking Cigarettes, Styles Survey, 2015

INTRODUCTION

Research suggests aerosol from electronic vapor products (EVPs) has fewer harmful constituents than conventional cigarette smoke. Even so, EVPs and other nicotine-containing products are not safe to use during pregnancy. We examined perceptions among US adults regarding harm in using EVPs rather than smoking cigarettes during pregnancy.

METHODS

Data came from the 2015 Styles Survey, an Internet panel survey of a sample of US adults aged 18 years or older (N = 4,127). Perceived harm was assessed by asking respondents whether using EVPs was less, equally, or more harmful for pregnant women than smoking cigarettes. Descriptive statistics were used to estimate perceived harm overall and by sociodemographic characteristics and tobacco-use status. Perceived harm was assessed among all adults, women of reproductive age (18-44 years, n = 820), and women of nonreproductive age (≥45 years, n = 1,398).

RESULTS

Among all adults, 11.1% believed using EVPs during pregnancy was less harmful than smoking conventional cigarettes, 51.0% believed it was equally harmful, 11.6% believed it was more harmful, and 26.2% did not know. Prevalence of perception of less harm, by demographic category, was greatest among adults aged 18 to 24 years, men, non-Hispanic whites, adults with less than a high school diploma, current EVP users, and current cigarette smokers (P < .05). Prevalence of perception of less harm was greater among women of reproductive age (9.6%) than among those of nonreproductive age (7.9%) (P < .05).

CONCLUSION

US adults have varying levels of perceptions about the harms of EVP use versus cigarette smoking during pregnancy. Efforts are warranted to prevent nicotine exposure during pregnancy and to educate adults on the dangers of using any form of tobacco during pregnancy, including EVPs.

The mutagenic assessment of an electronic-cigarette and reference cigarette smoke using the Ames assay in strains TA98 and TA100

Salmonella typhimurium strains TA98 and TA100 were used to assess the mutagenic potential of the aerosol from a commercially available, rechargeable, closed system electronic-cigarette. Results obtained were compared to those for the mainstream smoke from a Kentucky reference (3R4F) cigarette. Two different test matrices were assessed. Aerosol generated from the e-cigarette was trapped on a Cambridge filter pad, eluted in DMSO and compared to cigarette smoke total particulate matter (TPM), which was generated in the same manner for mutagenicity assessment in the Salmonella assay. Fresh e-cigarette and cigarette smoke aerosols were generated on the Vitrocell® VC 10 smoking robot and compared using a modified scaled-down 35mm air agar interface (AAI) methodology. E-cigarette aerosol collected matter (ACM) was found to be non-mutagenic in the 85mm plate incorporation Ames assay in strains TA98 and TA100 conducted in accordance with OECD 471, when tested up to 2400μg/plate. Freshly generated e-cigarette aerosol was also found to be negative in both strains after an AAI aerosol exposure, when tested up to a 1L/min dilution for up to 3h. Positive control responses were observed in both strains, using benzo[a]pyrene, 2-nitrofluorene, sodium azide and 2-aminoanthracene in TA98 and TA100 in the presence and absence of metabolic activation respectively. In contrast, cigarette smoke TPM and aerosol from 3R4F reference cigarettes were found to be mutagenic in both tester strains, under comparable test conditions to that of e-cigarette exposure. Limited information exists on the mutagenic activity of captured e-cigarette particulates and whole aerosol AAI approaches. With the lower toxicant burden of e-cigarette aerosols compared to cigarette smoke, it is clear that a more comprehensive Ames package of data should be generated when assessing e-cigarettes, consisting of the standard OECD-five, TA98, TA100, TA1535, TA1537 (or TA97) and E. coli (or TA102). In addition, TA104 which is more sensitive to the carbonyl based compounds found in e-cigarette aerosols under dry-wicking conditions may also prove a useful addition in a testing battery. Regulatory standard product testing approaches as used in this study will become important when determining whether e-cigarette aerosols are in fact less biologically active than cigarette smoke, as this study suggests. Future studies should be supported by in vitro dosimetry approaches to draw more accurate comparisons between cigarette smoke, e-cigarette aerosol exposure and human use.

Crosstalk between oral and general health status in e-smokers

Electronic cigarette (e-cigarette) simulates the act of tobacco smoking by vaporizing a mixture of propylene glycol, nicotine, and flavoring agents. e-cigarette has been proposed as a product able to aid to stop smoking. The aim of the study is to verify the clinical variations of periodontal health induced by e-cigarettes use and, moreover, to investigate about the awareness of the e-smokers about their health variations and about their hypothetical need to turn back to smoke combustible cigarettes.This clinical observational pilot study involved 110 out of 350 smokers, who switched to e-cigarette. Patients were subjected to oral examinations. A questionnaire to self-assess the variations of some parameters of general health, and to self-assess the need to smoke combustible cigarettes, was distributed to such subjects involved in the study.At the end of the study, we registered a progressive improvement in the periodontal indexes, as well as in the general health perception. Finally, many patients reported an interesting reduction in the need to smoke.In the light of this pilot study, the e-cigarette can be considered as a valuable alternative to tobacco cigarettes, but with a positive impact on periodontal and general health status.

Toxicity evaluation of e-juice and its soluble aerosols generated by electronic cigarettes using recombinant bioluminescent bacteria responsive to specific cellular damages

Electronic-cigarettes (e-cigarette) are widely used as an alternative to traditional cigarettes but their safety is not well established. Herein, we demonstrate and validate an analytical method to discriminate the deleterious effects of e-cigarette refills (e-juice) and soluble e-juice aerosol (SEA) by employing stress-specific bioluminescent recombinant bacterial cells (RBCs) as whole-cell biosensors. These RBCs carry luxCDABE-operon tightly controlled by promoters that specifically induced to DNA damage (recA), superoxide radicals (sodA), heavy metals (copA) and membrane damage (oprF). The responses of the RBCs following exposure to various concentrations of e-juice/SEA was recorded in real-time that showed dose-dependent stress specific-responses against both the e-juice and vaporized e-juice aerosols produced by the e-cigarette. We also established that high doses of e-juice (4-folds diluted) lead to cell death by repressing the cellular machinery responsible for repairing DNA-damage, superoxide toxicity, ion homeostasis and membrane damage. SEA also caused the cellular damages but the cells showed enhanced bioluminescence expression without significant growth inhibition, indicating that the cells activated their global defense system to repair these damages. DNA fragmentation assay also revealed the disintegration of total cellular DNA at sub-toxic doses of e-juice. Despite their state of matter, the e-juice and its aerosols induce cytotoxicity and alter normal cellular functions, respectively that raises concerns on use of e-cigarettes as alternative to traditional cigarette. The ability of RBCs in detecting both harmful effects and toxicity mechanisms provided a fundamental understanding of biological response to e-juice and aerosols.

A review of the additive health risk of cannabis and tobacco co-use

INTRODUCTION

Cannabis and tobacco are the most widely used substances, and are often used together. The present review examines the toxicant exposure associated with co-use (e.g., carbon monoxide, carcinogens), co-use via electronic nicotine delivery systems (ENDS), and problematic methodological issues present across co-use studies.

METHOD

An extensive literature search through PubMed was conducted and studies utilizing human subjects and in vitro methods were included. Keywords included tobacco, cigarette, e-cigarette, ENDS, smoking, or nicotine AND marijuana OR cannabis OR THC.

RESULTS

Co-use may pose additive risk for toxicant exposure as certain co-users (e.g., blunt users) tend to have higher breath carbon monoxide levels and cannabis smoke can have higher levels of some carcinogens than tobacco smoke. Cannabis use via ENDS is low and occurs primarily among established tobacco or cannabis users, but its incidence may be increasing and expanding to tobacco/cannabis naïve individuals. There are several methodological issues across co-use research including varying definitions of co-use, sample sizes, lack of control for important covariates (e.g., time since last cigarette), and inconsistent measurement of outcome variables.

CONCLUSIONS

There are some known additive risks for toxicant exposure as a result of co-use. Research utilizing consistent methodologies is needed to further establish the additive risk of co-use. Future research should also be aware of novel technologies (e.g., ENDS) as they likely alter some toxicant exposure when used alone and with cannabis.

To Regulate or Not to Regulate? Views on Electronic Cigarette Regulations and Beliefs about the Reasons for and against Regulation

Background

Policies designed to restrict marketing, access to, and public use of electronic cigarettes (e-cigarettes) are increasingly under debate in various jurisdictions in the US. Little is known about public perceptions of these policies and factors that predict their support or opposition.

Methods

Using a sample of US adults from Amazon Mechanical Turk in May 2015, this paper identifies beliefs about the benefits and costs of regulating e-cigarettes and identifies which of these beliefs predict support for e-cigarette restricting policies.

Results

A higher proportion of respondents agreed with 8 different reasons to regulate e-cigarettes (48.5% to 83.3% agreement) versus 7 reasons not to regulate e-cigarettes (11.5% to 18.9%). The majority of participants agreed with 7 out of 8 reasons for regulation. When all reasons to regulate or not were included in a final multivariable model, beliefs about protecting people from secondhand vapor and protecting youth from trying e-cigarettes significantly predicted stronger support for e-cigarette restricting policies, whereas concern about government intrusion into individual choices was associated with reduced support.

Discussion

This research identifies key beliefs that may underlie public support or opposition to policies designed to regulate the marketing and use of e-cigarettes. Advocates on both sides of the issue may find this research valuable in developing strategic campaigns related to the issue.

Implications

Specific beliefs of potential benefits and costs of e-cigarette regulation (protecting youth, preventing exposure to secondhand vapor, and government intrusion into individual choices) may be effectively deployed by policy makers or health advocates in communicating with the public.

Electronic Cigarette Refill Liquids: Child-Resistant Packaging, Nicotine Content, and Sales to Minors

To determine the accuracy of the labeled quantity of the nicotine content of the e-liquids sold in unlicensed vape stores, whether the packaging of e-liquids sold within the vape stores was child-resistant, whether minors were present within vape stores, and whether sales to minors occurred. This study was conducted across North Dakota prior to implementation of a new e-cigarette state law and provided a baseline assessment before enactment of the new legal requirements.

DESIGN AND METHODS

We tested samples of e-liquids and performed observations in 16 stores that were selling e-cigarettes but were not legally required to be licensed for tobacco retail. The e-liquids were analyzed for nicotine content using a validated high-performance liquid chromatography method for nicotine analysis.

RESULTS

Of the 70 collected e-liquid samples that claimed to contain nicotine, 17% contained more than the labeled quantity and 34% contained less than the labeled quantity by 10% or more, with one sample containing 172% more than the labeled quantity. Of the 94 e-liquid containers sampled, only 35% were determined to be child-resistant. Minors were present in stores, although no sales to minors occurred.

CONCLUSIONS

Mislabeling of nicotine in e-liquids is common and exposes the user to the harmful effects of nicotine. The lack of child-resistant packaging for this potentially toxic substance is a serious public health problem. E-cigarettes should be included in the legal definition of tobacco products, child-resistant packaging and nicotine labeling laws should be enacted and strictly enforced, and vape stores should be licensed by states.

Tobacco Use Disorders

Tobacco use is a pervasive public health problem and the leading cause of preventable morbidity and mortality in the United States. This article reviews the epidemiology of tobacco use in youth, with a description of cigarettes, alternative tobacco product, and polytobacco use patterns among the general population and among adolescents with psychiatric and/or substance use disorders. The article also provides an update on the diagnosis and assessment of tobacco use disorder in adolescents, with a particular focus on the clinical management of tobacco use in adolescents with co-occurring disorders.

E-cigarette aerosols induce lower oxidative stress in vitro when compared to tobacco smoke

Tobacco smoking is a risk factor for various diseases. The underlying cellular mechanisms are not fully characterized, but include oxidative stress, apoptosis, and necrosis. Electronic-cigarettes (e-cigarettes) have emerged as an alternative to and a possible means to reduce harm from tobacco smoking. E-cigarette vapor contains significantly lower levels of toxicants than cigarette smoke, but standardized methods to assess cellular responses to exposure are not well established. We investigated whether an in vitro model of the airway epithelium (human bronchial epithelial cells) and commercially available assays could differentiate cellular stress responses to aqueous aerosol extracts (AqE) generated from cigarette smoke and e-cigarette aerosols. After exposure to AqE concentrations of 0.063-0.500 puffs/mL, we measured the intracellular glutathione ratio (GSH:GSSG), intracellular generation of oxidant species, and activation of the nuclear factor erythroid-related factor 2 (Nrf2)-controlled antioxidant response elements (ARE) to characterize oxidative stress. Apoptotic and necrotic responses were characterized by increases in caspase 3/7 activity and reductions in viable cell protease activities. Concentration-dependent responses indicative of oxidative stress were obtained for all endpoints following exposure to cigarette smoke AqE: intracellular generation of oxidant species increased by up to 83%, GSH:GSSG reduced by 98.6% and transcriptional activation of ARE increased by up to 335%. Caspase 3/7 activity was increased by up to 37% and the viable cell population declined by up to 76%. No cellular stress responses were detected following exposure to e-cigarette AqE. The methods used were suitably sensitive to be employed for comparative studies of tobacco and nicotine products.

A framework for in vitro systems toxicology assessment of e-liquids

Various electronic nicotine delivery systems (ENDS), of which electronic cigarettes (e-cigs) are the most recognized prototype, have been quickly gaining ground on conventional cigarettes because they are perceived as less harmful. Research assessing the potential effects of ENDS exposure in humans is currently limited and inconclusive. New products are emerging with numerous variations in designs and performance parameters within and across brands. Acknowledging these challenges, we present here a proposed framework for an in vitro systems toxicology assessment of e-liquids and their aerosols, intended to complement the battery of assays for standard toxicity assessments. The proposed framework utilizes high-throughput toxicity assessments of e-liquids and their aerosols, in which the device-to-device variability is minimized, and a systems-level investigation of the cellular mechanisms of toxicity is an integral part. An analytical chemistry investigation is also included as a part of the framework to provide accurate and reliable chemistry data solidifying the toxicological assessment. In its simplest form, the framework comprises of three main layers: (1) high-throughput toxicity screening of e-liquids using primary human cell culture systems; (2) toxicity-related mechanistic assessment of selected e-liquids, and (3) toxicity-related mechanistic assessment of their aerosols using organotypic air-liquid interface airway culture systems. A systems toxicology assessment approach is leveraged to enable in-depth analyses of the toxicity-related cellular mechanisms of e-liquids and their aerosols. We present example use cases to demonstrate the suitability of the framework for a robust in vitro assessment of e-liquids and their aerosols.

Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells

The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs) to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-Cigarettes

BACKGROUND

There are > 7,000 e-cigarette flavors currently marketed. Flavoring chemicals gained notoriety in the early 2000s when inhalation exposure of the flavoring chemical diacetyl was found to be associated with a disease that became known as "popcorn lung." There has been limited research on flavoring chemicals in e-cigarettes.

OBJECTIVE

We aimed to determine if the flavoring chemical diacetyl and two other high-priority flavoring chemicals, 2,3-pentanedione and acetoin, are present in a convenience sample of flavored e-cigarettes.

METHODS

We selected 51 types of flavored e-cigarettes sold by leading e-cigarette brands and flavors we deemed were appealing to youth. E-cigarette contents were fully discharged and the air stream was captured and analyzed for total mass of diacetyl, 2,3-pentanedione, and acetoin, according to OSHA method 1012.

RESULTS

At least one flavoring chemical was detected in 47 of 51 unique flavors tested. Diacetyl was detected above the laboratory limit of detection in 39 of the 51 flavors tested, ranging from below the limit of quantification to 239 μg/e-cigarette. 2,3-Pentanedione and acetoin were detected in 23 and 46 of the 51 flavors tested at concentrations up to 64 and 529 μg/e-cigarette, respectively.

CONCLUSION

Because of the associations between diacetyl and bronchiolitis obliterans and other severe respiratory diseases observed in workers, urgent action is recommended to further evaluate this potentially widespread exposure via flavored e-cigarettes.

CITATION

Allen JG, Flanigan SS, LeBlanc M, Vallarino J, MacNaughton P, Stewart JH, Christiani DC. 2016. Flavoring chemicals in e-cigarettes: diacetyl, 2,3-pentanedione, and acetoin in a sample of 51 products, including fruit-, candy-, and cocktail-flavored e-cigarettes. Environ Health Perspect 124:733-739; http://dx.doi.org/10.1289/ehp.1510185.

Cigarette smoke but not electronic cigarette aerosol activates a stress response in human coronary artery endothelial cells in culture

BACKGROUND

It is generally acknowledged that e-cigarettes are unlikely to be as harmful as conventional cigarettes, but there is little data that quantifies their relative harms. We investigated the biological response to e-cigarette aerosol exposure (versus conventional cigarette smoke exposure) at the cellular level, by exposing human coronary artery endothelial cells (HCAEC) to aqueous filtered extracts of e-cigarette aerosol or cigarette smoke and looking at gene expression changes consistent with a stress response. This included genes controlled by the oxidant-stress sensing transcription factor NFR2 (NFE2L2), and cytochrome P450 family members.

METHODS

Cigarette smoke extract (CSE) was created using mainstream smoke from a single cigarette drawn through 10ml of endothelial cell growth media MV2. Electronic cigarette aerosol extract (eCAE) was created using the same apparatus, using a constant power output of 10.8w (4.2V) and 18mg/ml nicotine solution. eCAE was generated using 5 cycles of 5s heat with at least 10s in between each puff to allow the coil to cool, air being drawn through the device at 70ml/minute.

RESULTS

HCAEC responded to the noxious components in CSE, resulting in activation of NRF2 and upregulation of cytochrome p450. However, eCAE did not induce NRF2 nuclear localisation, upregulation of NRF2-activated genes, or the upregulation of cytochrome p450.

CONCLUSIONS

The use of e-cigarettes as a substitute for conventional cigarettes is likely to reduce immediate tobacco-related harm, at least with respect to cardiovascular harms.

The effects of nicotine on human fetal development

Maternal smoking during pregnancy continues to represent a major public health concern. Nicotine is extremely harmful to the developing fetus through many different mechanisms, and the harms increase with later gestational age at exposure. Pregnancies complicated by maternal nicotine use are more likely to have significant adverse outcomes. Nicotine-exposed children tend to have several health problems throughout their lives, including impaired function of the endocrine, reproductive, respiratory, cardiovascular, and neurologic systems. Poor academic performance and significant behavioral disruptions are also common, including ADHD, aggressive behaviors, and future substance abuse. To diminish the adverse effects from cigarette smoking, some women are turning to electronic cigarettes, a new trend that is increasing in popularity worldwide. They are largely perceived as being safer to use in pregnancy than traditional cigarettes, although there is not adequate evidence to support this claim. At this time, electronic cigarette use during pregnancy cannot be recommended. Birth Defects Research (Part C) 108:181-192, 2016. © 2016 Wiley Periodicals, Inc.

Knowledge and Perceptions about Nicotine, Nicotine Replacement Therapies and Electronic Cigarettes among Healthcare Professionals in Greece

Introduction. The purpose of this study was to evaluate the knowledge and perceptions of Greek healthcare professionals about nicotine, nicotine replacement therapies and electronic cigarettes. Methods. An online survey was performed, in which physicians and nurses working in private and public healthcare sectors in Athens-Greece were asked to participate through email invitations. A knowledge score was calculated by scoring the correct answers to specific questions with 1 point. Results. A total of 262 healthcare professionals were included to the analysis. Most had daily contact with smokers in their working environment. About half of them considered that nicotine has an extremely or very important contribution to smoking-related disease. More than 30% considered nicotine replacement therapies equally or more addictive than smoking, 76.7% overestimated their smoking cessation efficacy and only 21.0% would recommend them as long-term smoking substitutes. For electronic cigarettes, 45.0% considered them equally or more addictive than smoking and 24.4% equally or more harmful than tobacco cigarettes. Additionally, 35.5% thought they involve combustion while the majority responded that nicotine in electronic cigarettes is synthetically produced. Only 14.5% knew about the pending European regulation, but 33.2% have recommended them to smokers in the past. Still, more than 40% would not recommend electronic cigarettes to smokers unwilling or unable to quit smoking with currently approved medications. Cardiologists and respiratory physicians, who are responsible for smoking cessation therapy in Greece, were even more reluctant to recommend electronic cigarettes to this subpopulation of smokers compared to all other participants. The knowledge score of the whole study sample was 7.7 (SD: 2.4) out of a maximum score of 16. Higher score was associated with specific physician specialties. Conclusions. Greek healthcare professionals appear to overestimate the adverse effects of nicotine, and many would not recommend any nicotine-containing product as a long-term smoking substitute. Additionally, they have poor knowledge about the function and characteristics of electronic cigarettes.

Acute Exposure to Electronic and Combustible Cigarette Aerosols: Effects in an Animal Model and in Human Alveolar Cells

BACKGROUND

Smoking electronic cigarettes (ECIG) is promoted as a safer alternative to smoking combustible cigarettes. This study investigates the effects of ECIG aerosol and cigarette smoke (CS) in an animal model and in human alveolar cell cultures (A549).

METHODS

Mice were divided into Control, ECIG, and CS. Animals were exposed for 6h/d to either lab air, ECIG or CS, for of 3 days. Total particulate matter exposure for the ECIG was set at higher levels compared to CS. Lung injury was determined by: (1) measurement of wet-to-dry ratio; (2) albumin concentration in the bronchoalveolar lavage fluid; (3) transcriptional expression of inflammatory mediators IL-1β, IL-6, TNF-α; (4) oxidative stress; (5) assessment of cell death; and (6) lung histopathology. Human alveolar cell cultures were treated with various concentrations of ECIG and CS aerosol extracts and the effects on cell proliferation were evaluated.

RESULTS

Wet-to-dry ratio was higher in CS when compared to ECIG. Albumin leak in bronchoalveolar lavage fluid was evident in CS but not in ECIG. ECIG exposure was only associated with a significant increase in IL-1β. In contrast, CS exposure resulted in significant increases in IL-1β, IL-6, TNF-α expression, and oxidative stress. TUNEL staining demonstrated significant cell death in CS but not in ECIG. At the cellular level, ECIG and CS extracts reduced cell proliferation, however, CS exhibited effects at lower concentrations.

CONCLUSION

Despite higher exposure conditions, ECIG exhibited less toxic effects on lungs of experimental animals and on A549 cell cultures when compared to CS.

Frontal Cortex Transcriptome Analysis of Mice Exposed to Electronic Cigarettes During Early Life Stages

Electronic cigarettes (e-cigarettes), battery-powered devices containing nicotine, glycerin, propylene glycol, flavorings, and other substances, are increasing in popularity. They pose a potential threat to the developing brain, as nicotine is a known neurotoxicant. We hypothesized that exposure to e-cigarettes during early life stages induce changes in central nervous system (CNS) transcriptome associated with adverse neurobiological outcomes and long-term disease states. To test the hypothesis, pregnant C57BL/6 mice were exposed daily (via whole body inhalation) throughout gestation (3 h/day; 5 days/week) to aerosols produced from e-cigarettes either with nicotine (13-16 mg/mL) or without nicotine; following birth, pups and dams were exposed together to e-cigarette aerosols throughout lactation beginning at postnatal day (PND) 4-6 and using the same exposure conditions employed during gestational exposure. Following exposure, frontal cortex recovered from ~one-month-old male and female offspring were excised and analyzed for gene expression by RNA Sequencing (RNA-Seq). Comparisons between the treatment groups revealed that e-cigarette constituents other than nicotine might be partly responsible for the observed biological effects. Transcriptome alterations in both offspring sexes and treatment groups were all significantly associated with downstream adverse neurobiological outcomes. Results from this study demonstrate that e-cigarette exposure during early life alters CNS development potentially leading to chronic neuropathology.

The Electronic Cigarette: The Good, the Bad, and the Ugly

Electronic cigarettes (EC) are battery-powered nicotine delivery systems that have increased in popularity since they entered the US market. EC has been reported to contain less carcinogens than traditional cigarettes, cause less acute lung effects in healthy individuals, and may help with smoking cessation. It has also been viewed as a potential safer alternative for asthmatic smokers, but its effects on lung functions are unclear. However, EC do carry some harmful aspects as they contain formaldehyde and formaldehyde-forming hemiacetals as well as potentially toxic particulate matter that deposits on surfaces. EC are an increasingly popular device that could serve as a gateway into traditional cigarette smoking or illicit drugs. The popularity of EC has brought with it money from large tobacco corporations and mass marketing. Lack of regulation has generated product inconsistency and potential health hazards. This review highlights what is known and what still needs to be answered about EC.

Transcriptome sequencing reveals e-cigarette vapor and mainstream-smoke from tobacco cigarettes activate different gene expression profiles in human bronchial epithelial cells

Electronic cigarettes (e-cigarettes) generate an aerosol vapor (e-vapor) thought to represent a less risky alternative to main stream smoke (MSS) of conventional tobacco cigarettes. RNA-seq analysis was used to examine the transcriptomes of differentiated human bronchial epithelial (HBE) cells exposed to air, MSS from 1R5F tobacco reference cigarettes, and e-vapor with and without added nicotine in an in vitro air-liquid interface model for cellular exposure. Our results indicate that while e-vapor does not elicit many of the cell toxicity responses observed in MSS-exposed HBE cells, e-vapor exposure is not benign, but elicits discrete transcriptomic signatures with and without added nicotine. Among the cellular pathways with the most significantly enriched gene expression following e-vapor exposure are the phospholipid and fatty acid triacylglycerol metabolism pathways. Our data suggest that alterations in cellular glycerophopholipid biosynthesis are an important consequences of e-vapor exposure. Moreover, the presence of nicotine in e-vapor elicits a cellular response distinct from e-vapor alone including alterations of cytochrome P450 function, retinoid metabolism, and nicotine catabolism. These studies establish a baseline for future analysis of e-vapor and e-vapor additives that will better inform the FDA and other governmental bodies in discussions of the risks and future regulation of these products.

Association between Electronic Cigarette Use and Asthma among High School Students in South Korea

OBJECTIVES

Little is known about health outcomes related to electronic cigarette (EC) use, despite its growing popularity. The aim of this study is to investigate the association between EC use and asthma.

METHODS

The study design is a cross-sectional study. A total of 35,904 high school students were included as the final study population. The presence of asthma was based on a student's self-reported doctor diagnosis of asthma in the past 12 months.

RESULTS

Prevalence rates of asthmatics in 'current EC users' (n = 2,513), 'former EC users' (n = 2,078), and 'never EC users' (n = 31,313), were 3.9% (n = 98), 2.2% (n = 46) and 1.7% (n = 530), respectively. Comparing 'current EC' users with 'never EC' users, the unadjusted OR for asthma was 2.36 (95% CI: 1.89-2.94). In order to control for the effect of conventional cigarette (CC) smoking, after stratifying the subjects by the three CC smoking categories (never CC, former CC, and current CC), within the 'never CC' category, the unadjusted OR for asthma for 'current EC' users was 3.41 (95% CI: 1.79-6.49), and the adjusted OR was 2.74 (95% CI: 1.30-5.78). Severe asthma was reflected by the number of days absent from school due to asthma symptoms; current EC users had the highest adjusted OR for severe asthma compared to 'never EC' users.

CONCLUSIONS

When compared to a reference population of high school students in South Korea, EC users have an increased association with asthma and are more likely to have had days absent from school due to severe asthma symptoms. In conclusion, the results indicate that EC use may be a risk factor for asthma. The results may be useful in developing a scientific basis for the evaluation of a potential health hazard by EC.