Will chronic e-cigarette use cause lung disease?

In Vitro Consequences of Electronic-Cigarette Flavoring Exposure on the Immature Lung

Background: The developing lung is uniquely susceptible and may be at increased risk of injury with exposure to e-cigarette constituents. We hypothesize that cellular toxicity and airway and vascular responses with exposure to flavored refill solutions may be altered in the immature lung. Methods: Fetal, neonatal, and adult ovine pulmonary artery smooth muscle cells (PASMC) were exposed to popular flavored nicotine-free e-cigarette refill solutions (menthol, strawberry, tobacco, and vanilla) and unflavored solvents: propylene glycol (PG) or vegetable glycerin (VG). Viability was assessed by lactate dehydrogenase assay. Brochodilation and vasoreactivity were determined on isolated ovine bronchial rings (BR) and pulmonary arteries (PA). Results: Neither PG or VG impacted viability of immature or adult cells; however, exposure to menthol and strawberry flavored solutions increased cell death. Neonatal cells were uniquely susceptible to menthol flavoring-induced toxicity, and all four flavorings demonstrated lower lethal doses (LD50) in immature PASMC. Exposure to flavored solutions induced bronchodilation of neonatal BR, while only menthol induced airway relaxation in adults. In contrast, PG/VG and flavored solutions did not impact vasoreactivity with the exception of menthol-induced relaxation of adult PAs. Conclusion: The immature lung is uniquely susceptible to cellular toxicity and altered airway responses with exposure to common flavored e-cigarette solutions.

Diffuse alveolar damage and e-cigarettes: Case report and review of literature

The prevalence of e-cigarette usage has increased in non-smokers and those who are planning to quit smoking since introduced in 2003. Although the potential long term adverse effects have not been studied in humans, there have been studies showing that e-cigarette vapor causes release of proinflammatory cytokines leading to cytotoxic damage to alveolar epithelial cells, increase in the release of fibroblast growth factor (FGF) in the alveolar epithelial cells which leads to fibroblastic proliferation, and increased risk of staphylococcus aureus and viral infections which are implicated in the pathogenesis of diffuse alveolar damage. We describe a case of a 47-year-old woman who was diagnosed with histologically confirmed diffuse alveolar damage (DAD). She had no significant medical history and she had been smoking e-cigarettes for 3 years prior to presentation. This case report describes the potential association between e-cigarettes and diffuse alveolar damage while making reference to relevant associated studies.

A proibição dos cigarros eletrônicos no Brasil: sucesso ou fracasso?

Resumo O Brasil foi um dos primeiros países do mundo a proibir os Dispositivos Eletrônicos de Fumar (DEFs), tal proibição foi motivada pela inexistência de evidências relativas às alegadas propriedades terapêuticas e da inocuidade destes produtos. Por conta de tal proibição, A Anvisa foi criticada, especialmente de grupos de usuários. Estes grupos argumentam que tal ação proibiu um produto que auxiliaria a cessação ao tabagismo e seria menos tóxico que os cigarros comuns. Assim sendo, surge o questionamento se esta decisão foi acertada ou não. Os dados disponíveis mostram que os DEFs possuem formulações diversas e algumas substâncias tóxicas são liberadas durante sua utilização em níveis significativos. Estudos em animais e em humanos demonstraram potencial efeito tóxico. Os DEFs também demostraram que podem afetar a saúde de fumantes passivos. Quanto a seu uso como ferramenta de cessação, os estudos ainda não são conclusivos. Observou-se também um alto grau de uso entre adolescentes em países que seu uso foi autorizado. Desta forma o Brasil ao proibir estes produtos, impediu que a população consumisse um produto sem comprovação que auxiliasse no tratamento do tabagismo, com indícios de significativa toxidade e altamente atrativo aos jovens.

E-cigarettes and head and neck cancers: A systematic review of the current literature

BACKGROUND

Cigarette smoking is a well-established risk factor for head and neck (HN) cancers. Use of electronic cigarettes (e-cigarettes) is gaining popularity, being advertised as benign alternatives to tobacco. A wide variety of potentially harmful chemical components with variable quantity have been identified in e-liquids and aerosols of e-cigarettes. However, use of e-cigarettes remains controversial due to conflicting evidence.

OBJECTIVES

We aimed to assess the association between e-cigarettes and HN cancers. We conducted a systematic review to evaluate the literature for evidence on carcinogenic effects of e-cigarettes in the pathogenesis of HN cancers.

TYPE OF REVIEW

Qualitative systematic review.

SEARCH STRATEGY

A PubMed/MEDLINE, Cochrane, CINAHL Plus, Trip Medical Database and Web of Science search was done for studies on e-cigarettes and HN cancer.

EVALUATION METHOD

Abstract review of all articles, full article revision of included studies, data extraction and quality assessment were performed by two independent assessors.

RESULTS

The literature search resulted in the identification of 359 articles. Eighteen articles were selected for inclusion into the systematic review. The majority were laboratory-based studies, followed by several cohort and case studies, representing low-level evidence. A few reports suggested DNA damage following exposure to e-cigarettes potentially due to increased oxidative stress. Flavoured e-liquids appear to be more harmful. There is variable evidence from clinical studies.

CONCLUSIONS

Our review outlines potential dangers associated with the use of e-cigarettes and their role in HN cancers. More longitudinal and controlled studies are needed to assess the possible link between e-cigarettes and HN cancers.

The role of E-liquid vegetable glycerin and exhaled aerosol on cue reactivity to tank-based electronic nicotine delivery systems (ENDS)

RATIONALE

Electronic nicotine delivery systems (ENDS or e-cigarettes) share salient features of combustible smoking, such as inhalation and exhalation behaviors, and evidence indicates that first- and second-generation ENDS generalize as smoking cues. The present study examined whether newer, tank-based third-generation ENDS ("mods") also evoke smoking urges, and whether enhancing the visibility of exhaled aerosol clouds-by increasing the e-liquid vegetable glycerin (VG) content-strengthens the cue salience of ENDS.

OBJECTIVES

The objective was to assess the role of exhaled aerosol clouds on ENDS cue potency using a standardized laboratory paradigm designed to mimic real-world exposures.

METHODS

Using a mixed design, young adult smokers (n = 50; mean age 26.5 years; ≥ 5 cigarettes/day) observed a study confederate drinking bottled water (control cue) and vaping an ENDS mod containing e-liquid with either high (73%) or low (0%) VG. Participants completed the Brief Questionnaire on Smoking Urges (BQSU) and visual analog scales (VAS) assessing cigarette and e-cigarette desire pre- and post-cue exposure.

RESULTS

Increasing the e-liquid content of VG enhanced the size and visibility of the exhaled aerosol clouds and evoked a greater increase in smoking desire and a more sustained increase in e-cigarette desire relative to the low VG cue. Both cues elicited increases in smoking urges. These results remained after controlling for sex, prior ENDS experience, recent smoking behavior, and menthol preference.

CONCLUSIONS

Observation of tank-based ENDS use generalizes as a smoking cue and its cue salience is strengthened by increasing the e-liquid content of VG to enhance the visibility of the exhaled aerosol cloud.

Chronic exposure to e-cig aerosols during early development causes vascular dysfunction and offspring growth deficits

Increasing popularity of electronic cigarettes (e-cigs), including among women of reproductive age, is attributed to its perceived safety compared to conventional tobacco. However, there is a major knowledge gap surrounding the effects of e-cig aerosols on pregnancy and fetal development. We aimed to evaluate the effects of vaping e-cigs during gestation on offspring growth and to asses if growth deficits are accompanied by altered maternal and fetal vascular hemodynamics. Sprague-Dawley dams were assigned to Pair-Fed Control, Pair-Fed Juice, or Juice+Nicotine groups, and then underwent either a prenatal or prenatal+postnatal exposure paradigm in a custom-engineered vaping system. Mass spectrometry identified major aerosolized constituents from e-cig vaping. The Juice+Nicotine group exhibited significantly decreased fetal weight and crown-rump length (↓46.56%, and ↓23.83%, respectively). Pre- and postnatal exposure to Juice+Nicotine resulted in decreased pup weight at postnatal day (PND) 4-10. Crown-rump length was decreased by 24.71% on PND 10. Blood flow in the Juice+Nicotine group was decreased in the maternal uterine and fetal umbilical circuits by 49.50% and 65.33%, respectively. We conclude that chronic exposure to e-cig aerosols containing nicotine during early development can have deleterious health effects on the exposed offspring. Vaping e-cigs containing nicotine during pregnancy lead to a reduction in offspring weight and crown-rump length, associated with a marked decrease in blood flow in both the maternal uterine and fetal umbilical circulation (a strong indicator of growth restriction). Thus, chronic exposure to e-cig aerosols containing nicotine can lead to potentially harmful developmental effects in early life.

Activation of TRPA1 by volatile organic chemicals leading to sensory irritation

Many volatile organic chemicals (VOCs) have not been tested for sensory pulmonary irritation. Development of in vitro non-animal sensory irritation assay suitable for a large number of chemicals is needed to replace the mouse assay. An adverse outcome pathway (AOP) is designed to provide a clear description of the biochemical and cellular processes leading to toxicological effects or an adverse outcome. The AOP for chemical sensory pulmonary irritation was developed according to the Organization for Economic Co-operation and Development guidance including the Bradford Hill criteria for a weight of evidence to determine the confidence of the AOP. The proposed AOP is based on an in-depth review of the relevant scientific literature to identify the initial molecular event for respiratory irritation. The activation of TRPA1 receptor (transient receptor potential cation channel, subfamily A, member 1) is the molecular initial event (MIE) leading to sensory irritation. A direct measure of TRPA1 activation in vitro should identify chemical sensory irritants and provide an estimate of potency. Fibroblasts expressing TRPA1 are used to determine TRPA1 activation and irritant potency. We report a linear relationship between the in vivo RD₅₀ and the in vitro pEC₅₀ values (R=0.81) to support this hypothesis. We propose that this in vitro assay after additional analysis and validation could serve as a suitable candidate to replace the mouse sensory irritation assay.

Comparison of the content of tobacco alkaloids and tobacco-specific nitrosamines in 'heat-not-burn' tobacco products before and after aerosol generation

Standardized methods for collecting smoke and for measuring smoke components in heat not burn tobacco product (HTP) are yet to be established, and there is a lack of consensus as to whether the content of HTP cigarettes can be assayed in the same manner as for conventional cigarettes. Since HTPcigarettes do not generate ash when smoked, we compared the levels of tobacco alkaloids (TAs) and tobacco-specific nitrosamines (TSNAs) of HTP cigarettes before and after aerosol generation. HTP cigarettes were smoked according to two international standardization methods. The TAs and TSNAs contents of the cigarettes were analyzed by UPLC-Q-TOF and UPLC-MSMS, respectively. Smoking was found to significantly decrease the content of nicotine, nornicotine, anatabine, and anabasine by 53 ∼ 100% in all samples, and the maximum inhalable amounts of these entities were determined to be 4.24 mg/cig, 103.52 μg/cig, 258.72 μg/cig, and 33.03 μg/cig, respectively. By contrast, smoking significantly increased the content of NNK and NAB. we suggested that the reduced nicotine content minus the nicotine content remaining in the filter is an amount that could potentially be inhaled during smoking. The increase of NNK and NAB in HTP cigarette after aerosol generation is expected to be caused by the precursor, but more specific behavioral studies should be performed.

Acute pulmonary effects of aerosolized nicotine

Nicotine is a highly addictive principal component of both tobacco and electronic cigarette that is readily absorbed in blood. Nicotine-containing electronic cigarettes are promoted as a safe alternative to cigarette smoking. However, the isolated effects of inhaled nicotine are largely unknown. Here we report a novel rat model of aerosolized nicotine with a particle size (~1 μm) in the respirable diameter range. Acute nicotine inhalation caused increased pulmonary edema and lung injury as measured by enhanced bronchoalveolar lavage fluid protein, IgM, lung wet-to-dry weight ratio, and high-mobility group box 1 (HMGB1) protein and decreased lung E-cadherin protein. Immunohistochemical analysis revealed congested blood vessels and increased neutrophil infiltration. Lung myeloperoxidase mRNA and protein increased in the nicotine-exposed rats. Complete blood counts also showed an increase in neutrophils, white blood cells, eosinophils, and basophils. Arterial blood gas measurements showed an increase in lactate. Lungs of nicotine-inhaling animals revealed increased mRNA levels of IL-1A and CXCL1. There was also an increase in IL-1α protein. In in vitro air-liquid interface cultures of airway epithelial cells, there was a dose dependent increase in HMGB1 release with nicotine treatment. Air-liquid cultures exposed to nicotine also resulted in a dose-dependent loss of barrier as measured by transepithelial electrical resistance and a decrease in E-cadherin expression. Nicotine also caused a dose-dependent increase in epithelial cell death and an increase in caspase-3/7 activities. These results show that the nicotine content of electronic cigarettes may have adverse pulmonary and systemic effects.

Heat or Burn? Impacts of Intrauterine Tobacco Smoke and E-Cigarette Vapor Exposure on the Offspring's Health Outcome

Maternal smoking during pregnancy leads to gestational complications and organ disorders in the offspring. As nicotine replacement therapy is often ineffective for smoking cessation, pregnant women turn to alternatives such as heat-not-burn tobacco and e-cigarettes. Recently, the popularly of e-cigarettes has been increasing especially among the youth and pregnant women, mainly due to the advertisements claiming their safety. This has even led to some clinicians recommending their use during pregnancy. E-cigarettes heat e-liquid to produce an aerosol (e-vapor), delivering flavorings and nicotine to the user. However, e-vapor also contains toxins such as formaldehyde along with heavy metals and carcinogenic nitrosamines. In addition, specific flavoring compounds such as diacetyl can be toxic themselves or decompose into toxic compounds such as benzaldehydes. These compounds can induce toxicity, inflammation and oxidative stress in the mothers and can accumulate in the developing fetus, affecting intrauterine development. Recent animal studies suggest that maternal e-vapor exposure during pregnancy could cause respiratory and neurological disorders in the offspring. This review will examine the available literature to shed light on the current understanding of this problem-to-be from lessons learned in animal models.

Children and E-Cigarettes: A New Threat to Health

The widespread availability and use of E-Cigarettes in many countries has established the need for an assessment of their effect on children. By the end of 2017 the number published annually on E-Cigarettes had increased to 2976 and included 171 papers on E-Cigarettes and children. The objective of this commentary is to provide a review and public health perspective on the effects of E-cigarettes on children. There are four public health questions to be answered:

1. Are E-Cigarettes and replenishing fluids toxic on accidental ingestion?

2. If children smoke E-Cigarettes is this harmful?

3. Does exposure to second hand vapour from E-Cigarettes cause harm to children?

4. Are children (adolescents) who use E Cigarettes more likely to begin smoking conventional cigarettes?

There were 2229 reported exposures to e-cigarette fluids and liquid nicotine in the USA in 2017 causing cardiovascular symptoms of varying severity. No deaths were reported although the potential is always there. Exposure to E-Cigarette vapor is less dangerous than cigarette smoke. However it does damage pulmonary endothelium in experimental models. No long term studies are yet available on chronic diseases although vapor does contain carcinogens. Adolescents who use E-Cigarettes are more likely to become tobacco smokers. Because of the accumulating evidence of harm to children great caution should be exercised in widening the public promotion and usage of E-Cigarettes. Children should avoid any contact with E-cigarettes or their vapour.

Physicochemical studies of direct interactions between lung surfactant and components of electronic cigarettes liquid mixtures

Direct physicochemical interactions between the major components of electronic cigarette liquids (e-liquids): glycerol (VG) and propylene glycol (PG), and lung surfactant (LS) were studied by determining the dynamic surface tension under a simulated breathing cycle using drop shape method. The studies were performed for a wide range of concentrations based on estimated doses of e-liquid aerosols (up to 2500 × the expected nominal concentrations) and for various VG/PG ratios. The results are discussed as relationships among mean surface tension, surface tension amplitude, and surface rheological properties (dilatational elasticity and viscosity) versus concentration and composition of e-liquid. The results showed that high local concentrations (>200 × higher than the estimated average dose after a single puffing session) may induce measurable changes in biophysical activity of LS; however, only ultra-high e-liquid concentrations inactivated the surfactant. Physiochemical characterization of e-liquids provide additional insights for the safety assessment of electronic nicotine delivery systems (ENDS).

E-cigarettes can emit formaldehyde at high levels under conditions that have been reported to be non-averse to users

E-cigarette aerosol emission studies typically focus on benchmarking toxicant levels versus those of cigarettes. However, such studies do not fully account for the distinct chemical makeup of e-liquids and their unique properties. These approaches often conclude that there are fewer and lower levels of toxins produced by e-cigarettes than by cigarettes. In 2015, we reported the discovery of new hemiacetals derived from the reaction of formaldehyde and the e-liquid solvents. The main finding was that they constituted a significant proportion of potentially undetected formaldehyde. Moreover, unlike gaseous formaldehyde, the hemiacetals reside in the aerosol particulate phase, and thus are capable of delivering formaldehyde more deeply into the lungs. However, the findings were criticized by those claiming that some of the results were obtained under conditions that are averse to vapers. A "reinvestigation" of our study was recently published addressing this latter issue. However, this reinvestigation ignored major details, including no mention of the formaldehyde hemiacetals. Herein, we isolated both gaseous formaldehyde and formaldehyde hemiacetals at an intermediate power level claimed, in the "reinvestigation", to be relevant to "non-averse," "normal" usage. The results were that both gaseous formaldehyde and formaldehyde from hemiacetals were produced at levels above OSHA workplace limits.

Assessing electronic cigarette emissions: linking physico-chemical properties to product brand, e-liquid flavoring additives, operational voltage and user puffing patterns

Users of electronic cigarettes (e-cigs) are exposed to particles and other gaseous pollutants. However, major knowledge gaps on the physico-chemical properties of such exposures and contradictory data in published literature prohibit health risk assessment. Here, the effects of product brand, type, e-liquid flavoring additives, operational voltage, and user puffing patterns on emissions were systematically assessed using a recently developed, versatile, e-cig exposure generation platform and state-of-the-art analytical methods. Parameters of interest in this systematic evaluation included two brands (A and B), three flavors (tobacco, menthol, and fruit), three types of e-cigs (disposable, pre-filled, and refillable tanks), two puffing protocols (4 and 2 s/puff), and four operational voltages (2.2-5.7 V). Particles were generated at a high number concentration (106-107 particles/cm3). The particle size distribution was bi-modal (∼200 nm and 1 µm). Furthermore, organic species (humectants propylene glycol and glycerin, nicotine) that were present in e-liquid and trace metals (potassium and sodium) that were present on e-cig heating coil were also released into the emission. In addition, combustion-related byproducts, such as benzene and toluene, were also detected in the range of 100-38,000 ppbv/puff. Parametric analyzes performed in this study show the importance of e-cig brand, type, flavor additives, user puffing pattern (duration and frequency), and voltage on physico-chemical properties of emissions. This observed influence is indicative of the complexity associated with the toxicological screening of emissions from e-cigs and needs to be taken into consideration.

Health impact of E-cigarettes: a prospective 3.5-year study of regular daily users who have never smoked

Although electronic cigarettes (ECs) are a much less harmful alternative to tobacco cigarettes, there is concern as to whether long-term ECs use may cause risks to human health. We report health outcomes (blood pressure, heart rate, body weight, lung function, respiratory symptoms, exhaled breath nitric oxide [eNO], exhaled carbon monoxide [eCO], and high-resolution computed tomography [HRCT] of the lungs) from a prospective 3.5-year observational study of a cohort of nine daily EC users (mean age 29.7 (±6.1) years) who have never smoked and a reference group of twelve never smokers. No significant changes could be detected over the observation period from baseline in the EC users or between EC users and control subjects in any of the health outcomes investigated. Moreover, no pathological findings could be identified on HRCT of the lungs and no respiratory symptoms were consistently reported in the EC user group. Although it cannot be excluded that some harm may occur at later stages, this study did not demonstrate any health concerns associated with long-term use of EC in relatively young users who did not also smoke tobacco.

The therapeutic potential of CFTR modulators for COPD and other airway diseases

Airways diseases, especially chronic obstructive pulmonary disease (COPD) and asthma, are common causes of morbidity and mortality worldwide. There is an ongoing unmet need for novel and effective therapies. There is an established pathophysiological link and phenotypic similarity between the chronic bronchitis phenotype of COPD and cystic fibrosis (CF). New evidence suggests that CFTR dysfunction may play a role in other common airways diseases such as COPD, non-atopic asthma and non-CF bronchiectasis. Newly approved and investigational drugs that target both mutant and wild-type CFTR channels have provided a new treatment opportunity addressing the mucus defect in pulmonary diseases that share the same pathophysiology with CF.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

Electronic cigarettes and indoor air quality: a review of studies using human volunteers

OBJECTIVE

This paper is primarily aimed to review articles on electronic cigarettes (e-cigarettes) focusing on indoor air quality (IAQ) assessment that were conducted using human volunteers under natural settings that mimic actual vaping scenarios. Such studies may give a better representation of the actual potential exposure towards e-cigarettes emissions in indoor settings.

METHODS

A systematic literature search was conducted using PubMed search engine database. Search terms such as "electronic cigarette", "e-cigarette", "electronic nicotine delivery system", and "indoor air quality" were used to identify the relevant articles to be included in this review. Articles that involved human volunteers who were asked to vape in natural settings or settings that mimic the actual vaping scenario were chosen to be reviewed. The search yielded a total of 15 published articles. Eleven articles were excluded due to 1) unavailability of its full-text (n=1), 2) did not involve human volunteers (n=5) and 3) did not involve an IAQ study (n=5). Four articles were critically reviewed in this paper.

RESULTS

From the four selected articles, two of the papers focused on the determination of nicotine level released by e-cigarettes whereas the other two covered IAQ parameters namely; particulate matters (PM), propylene glycols, formaldehyde, metals and polycyclic aromatic hydrocarbons (PAHs). Only two of the studies involved determination of biomarkers of exposure. The level of chemical contents released varied between studies. The differences in the brands of e-cigarette used, number of vapers recruited and the sensitivity of the methodologies employed in these studies may be the possible causes for such differences. However, studies using human volunteers conducted in a natural setting are more relevant to portray the actual exposure to vapors among e-cigarettes users and non-users compared to studies using a smoking machine/an exposure chamber. This is because such studies take into account the behavior of consumers and individual retention of nicotine. Such method will therefore avoid the possibility of overestimation in terms of exposures toward e-cigarettes users and non-users.

CONCLUSION

There are limited e-cigarette studies on the impact of IAQ performed using human volunteers in natural settings. The available studies however, provided inconsistent scientific evidence on the actual exposure towards the vapor contents as unstandardized methodology were used in conducting such research. Therefore, there is a need to conduct IAQ studies in natural settings by using a standardized protocol in terms of the number of vapers recruited, the size of the indoor settings, the methods used in detecting and quantifying the contents and levels of emissions and the sensitivity of the equipment used in analyzing the contents. This will help in better utilization of the findings from such studies for the use of risk assessment of the exposures towards e-cigarette emissions. There is also a need to emphasize that it is the onus of the manufacturers in providing and proving scientifically sound safety claims for their products prior to commercializing it in the market.

A randomized controlled trial of a smoking cessation self-help intervention for dual users of tobacco cigarettes and E-cigarettes: Intervention development and research design

Electronic Nicotine Delivery Systems, also called electronic cigarettes or e-cigarettes, have been available for over a decade and use has been increasing dramatically. The primary reported reasons for use are to aid smoking cessation or reduction, yet a significant proportion appear to be long-term users of both products ("dual users"). Dual users may be motivated to quit smoking and might benefit from a behavioral intervention for smoking cessation. This paper describes the intervention development, as well as the design, methods, and data analysis plans for an ongoing randomized controlled trial (RCT). Formative research and learner verification were conducted to create a usable, understandable, and acceptable self-help intervention targeting dual users. The efficacy is being tested in an RCT with current dual users (N=2900) recruited nationally and randomized to one of three conditions. The Assessment Only (ASSESS) group only completes assessments. The Generic Self-Help (GENERIC) group receives non-targeted smoking cessation booklets and supplemental materials sent monthly over 18months. The e-cigarette Targeted Self-Help (eTARGET) group receives the newly developed intervention (targeted booklets and supplemental materials) sent over the same period. All participants complete self-report surveys every 3months over 2years. The primary study outcome is self-reported 7-day point prevalence abstinence. Cost-effectiveness metrics for the GENERIC and eTARGET interventions will also be calculated.

A Review of Pulmonary Toxicity of Electronic Cigarettes in the Context of Smoking: A Focus on Inflammation

The use of electronic cigarettes (e-cigs) is increasing rapidly, but their effects on lung toxicity are largely unknown. Smoking is a well-established cause of lung cancer and respiratory disease, in part through inflammation. It is plausible that e-cig use might affect similar inflammatory pathways. E-cigs are used by some smokers as an aid for quitting or smoking reduction, and by never smokers (e.g., adolescents and young adults). The relative effects for impacting disease risk may differ for these groups. Cell culture and experimental animal data indicate that e-cigs have the potential for inducing inflammation, albeit much less than smoking. Human studies show that e-cig use in smokers is associated with substantial reductions in blood or urinary biomarkers of tobacco toxicants when completely switching and somewhat for dual use. However, the extent to which these biomarkers are surrogates for potential lung toxicity remains unclear. The FDA now has regulatory authority over e-cigs and can regulate product and e-liquid design features, such as nicotine content and delivery, voltage, e-liquid formulations, and flavors. All of these factors may impact pulmonary toxicity. This review summarizes current data on pulmonary inflammation related to both smoking and e-cig use, with a focus on human lung biomarkers. Cancer Epidemiol Biomarkers Prev; 26(8); 1175-91. ©2017 AACR.

The association between environmental tobacco smoke exposure and childhood respiratory disease: a review

INTRODUCTION

Childhood respiratory illness is a major cause of morbidity and mortality particularly in low and middle-income countries. Environmental tobacco smoke (ETS) exposure is a recognised risk factor for both acute and chronic respiratory illness. Areas covered: The aim of this paper was to review the epidemiology of ETS exposure and impact on respiratory health in children. We conducted a search of 3 electronic databases of publications on ETS and childhood respiratory illness from 1990-2015. Key findings were that up to 70% of children are exposed to ETS globally, but under-reporting may mask the true prevalence. Maternal smoking and ETS exposure influence infant lung development and are associated with childhood upper and lower respiratory tract infection, wheezing or asthma. Further, exposure to ETS is associated with more severe respiratory disease. ETS exposure reduces lung function early in life, establishing an increased lifelong risk of poor lung health. Expert commentary: Urgent and effective strategies are needed to decrease ETS exposure in young children to improve child and long-term lung health in adults especially in low and middle income countries where ETS exposure is increasing.

Electronic Cigarette Use and Respiratory Symptoms in Adolescents

RATIONALE

Rates of adolescent electronic (e-) cigarette use are increasing, but there has been little study of the chronic effects of use. Components of e-cigarette aerosol have known pulmonary toxicity.

OBJECTIVES

To investigate the associations of e-cigarette use with chronic bronchitis symptoms and wheeze in an adolescent population.

METHODS

Associations of self-reported use of e-cigarettes with chronic bronchitic symptoms (chronic cough, phlegm, or bronchitis) and of wheeze in the previous 12 months were examined in 2,086 Southern California Children's Health Study participants completing questionnaires in 11th and 12th grade in 2014.

MEASUREMENTS AND MAIN RESULTS

Ever e-cigarette use was reported by 502 (24.0%), of whom 201 (9.6%) used e-cigarettes during the last 30 days (current users). Risk of bronchitic symptoms was increased by almost twofold among past users (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.37-2.49), compared with never-users, and by 2.02-fold (95% CI, 1.42-2.88) among current users. Risk increased with frequency of current use (OR, 1.66; 95% CI, 1.02-2.68) for 1-2 days and 2.52 (95% CI, 1.56-4.08) for 3 or more days in past 30 days compared with never-users. Associations were attenuated by adjustment for lifetime number of cigarettes smoked and secondhand smoke exposure. However, risk of bronchitic symptoms among past e-cigarette users remained elevated after adjustment for relevant potential confounders and was also observed among never-cigarette users (OR, 1.70; 95% CI, 1.11-2.59). There were no statistically significant associations of e-cigarette use with wheeze after adjustment for cigarette use.

CONCLUSIONS

Adolescent e-cigarette users had increased rates of chronic bronchitic symptoms. Further investigation is needed to determine the long-term effects of e-cigarettes on respiratory health.

Flavored e-cigarette liquids reduce proliferation and viability in the CALU3 airway epithelial cell line

E-cigarettes are generally thought of as a safer smoking alternative to traditional cigarettes. However, little is known about the effects of e-cigarette liquids (e-liquids) on the lung. Since over 7,000 unique flavors have been identified for purchase in the United States, our goal was to conduct a screen that would test whether different flavored e-liquids exhibited different toxicant profiles. We tested the effects of 13 different flavored e-liquids [with nicotine and propylene glycol/vegetable glycerin (PG/VG) serving as controls] on a lung epithelial cell line (CALU3). Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as an indicator of cell proliferation/viability, we demonstrated a dose-dependent decrease of MTT metabolism by all flavors tested. However, a group of four flavors consistently showed significantly greater toxicity compared with the PG/VG control, indicating the potential for some flavors to elicit more harmful effects than others. We also tested the aerosolized "vapor" from select e-liquids on cells and found similar dose-dependent trends, suggesting that direct e-liquid exposures are a justifiable first-pass screening approach for determining relative e-liquid toxicity. We then identified individual chemical constituents for all 13 flavors using gas chromatography-mass spectrometry. These data revealed that beyond nicotine and PG/VG, the 13 flavored e-liquids have diverse chemical constituents. Since all of the flavors exhibited some degree of toxicity and a diverse array of chemical constituents with little inhalation toxicity available, we conclude that flavored e-liquids should be extensively tested on a case-by-case basis to determine the potential for toxicity in the lung and elsewhere.

Cardiovascular effects of electronic cigarettes

Cardiovascular safety is an important consideration in the debate on the benefits versus the risks of electronic cigarette (EC) use. EC emissions that might have adverse effects on cardiovascular health include nicotine, oxidants, aldehydes, particulates, and flavourants. To date, most of the cardiovascular effects of ECs demonstrated in humans are consistent with the known effects of nicotine. Pharmacological and toxicological studies support the biological plausibility that nicotine contributes to acute cardiovascular events and accelerated atherogenesis. However, epidemiological studies assessing Swedish smokeless tobacco, which exposes users to nicotine without combustion products, generally have not found an increased risk of myocardial infarction or stroke among users, but suggest that nicotine might contribute to acute cardiovascular events, especially in those with underlying coronary heart disease. The effects of aldehydes, particulates, and flavourants derived from ECs on cardiovascular health have not been determined. Although ECs might pose some cardiovascular risk to users, particularly those with existing cardiovascular disease, the risk is thought to be less than that of cigarette smoking based on qualitative and quantitative comparisons of EC aerosol versus cigarette smoke constituents. The adoption of ECs rather than cigarette smoking might, therefore, result in an overall benefit for public health.

Solvent Chemistry in the Electronic Cigarette Reaction Vessel

Knowledge of the mechanism of formation, levels and toxicological profiles of the chemical products in the aerosols (i.e., vapor plus particulate phases) of e-cigarettes is needed in order to better inform basic research as well as the general public, regulators, and industry. To date, studies of e-cigarette emissions have mainly focused on chromatographic techniques for quantifying and comparing the levels of selected e-cigarette aerosol components to those found in traditional cigarettes. E-cigarettes heat and aerosolize the solvents propylene glycol (PG) and glycerol (GLY), thereby affording unique product profiles as compared to traditional cigarettes. The chemical literature strongly suggests that there should be more compounds produced by PG and GLY than have been reported in e-cigarette aerosols to date. Herein we report an extensive investigation of the products derived from vaporizing PG and GLY under mild, single puff conditions. This has led to the discovery of several new compounds produced under vaping conditions. Prior reports on e-cigarette toxin production have emphasized temperature as the primary variable in solvent degradation. In the current study, the molecular pathways leading to enhanced PG/GLY reactivity are described, along with the most impactful chemical conditions promoting byproduct production.

Overview of Electronic Nicotine Delivery Systems: A Systematic Review

CONTEXT

Rapid developments in e-cigarettes, or electronic nicotine delivery systems (ENDS), and the evolution of the overall tobacco product marketplace warrant frequent evaluation of the published literature. The purpose of this article is to report updated findings from a comprehensive review of the published scientific literature on ENDS.

EVIDENCE ACQUISITION

The authors conducted a systematic review of published empirical research literature on ENDS through May 31, 2016, using a detailed search strategy in the PubMed electronic database, expert review, and additional targeted searches. Included studies presented empirical findings and were coded to at least one of nine topics: (1) Product Features; (2) Health Effects; (3) Consumer Perceptions; (4) Patterns of Use; (5) Potential to Induce Dependence; (6) Smoking Cessation; (7) Marketing and Communication; (8) Sales; and (9) Policies; reviews and commentaries were excluded. Data from included studies were extracted by multiple coders (October 2015 to August 2016) into a standardized form and synthesized qualitatively by topic.

EVIDENCE SYNTHESIS

There were 687 articles included in this systematic review. The majority of studies assessed patterns of ENDS use and consumer perceptions of ENDS, followed by studies examining health effects of vaping and product features.

CONCLUSIONS

Studies indicate that ENDS are increasing in use, particularly among current smokers, pose substantially less harm to smokers than cigarettes, are being used to reduce/quit smoking, and are widely available. More longitudinal studies and controlled trials are needed to evaluate the impact of ENDS on population-level tobacco use and determine the health effects of longer-term vaping.

Toxicological and analytical assessment of e-cigarette refill components on airway epithelia

There are over 2.6 million users of e-cigarettes in the United Kingdom alone as they have been promoted as a safer alternative to traditional cigarettes. The addition of flavours and aromas has also proven to be popular with younger generations. In this review, we survey the range of studies in the short timeframe since e-cigarettes reached the market to draw attention to the health associated risks and benefits of their introduction. We complement this review with a case study reporting on the composition of selected e-cigarette refills with particular emphasis on the toxicological activity of its components on lung cells.

Potential health effects of electronic cigarettes: A systematic review of case reports

The health risks associated with electronic cigarettes (ECs) are largely unknown. The purpose of this systematic review was to evaluate published case reports that deal with health effects attributed to EC use. An Internet search was conducted to identify case reports dealing with the effects of EC use on health. Twenty-six case reports representing 27 individuals (one study contained reports for two individuals) were published between April 2012 and January 2016, and these were grouped into categories of effect according to their health outcomes. Of the 27 individuals, 25 had negative effects subsequent to use or exposure to ECs and their refill fluids, while two reported improvement in chronic immune and gastrointestinal conditions. Three categories of negative health effects were identified: systemic effects, nicotine poisoning, and mechanical injury. Thirteen cases reported EC effects on different systems including: respiratory (6), gastrointestinal or developing intestine of an infant (3), cardiovascular (2), neurological (1), and immune (1). Twelve cases involved nicotine poisoning resulting from accidental (N = 3), misuse/abuse (N = 1), or suicidal/intentional ingestion (N = 8); four of these involved children and three resulted in adult fatalities. Two cases reported mechanical injury caused by an EC battery explosion. Most case reports show that the health of children and adults can be negatively affected by EC products and that if death does not occur, negative effects can be reversed. Data further indicate that EC use can cause negative health effects in previously healthy individuals and exacerbate pre-existing conditions.

Development and characterization of electronic-cigarette exposure generation system (Ecig-EGS) for the physico-chemical and toxicological assessment of electronic cigarette emissions

Electronic cigarettes (e-cig) have been introduced as a nicotine replacement therapy and have gained increasing attention and popularity. However, while findings on possible toxicological implications continue to grow, major knowledge gaps on both the complex chemistry of the exposure and toxicity exist, prohibiting public health assessors from assessing risks. Here, a versatile electronic cigarette exposure generation system (Ecig-EGS) has been developed and characterized. Ecig-EGS allows generation of real world e-cig emission profiles under controlled operational conditions, real time monitoring and time-integrated particle/gas sampling for physico-chemical characterization, and toxicological assessment (both in vitro and in vivo). The platform is highly versatile and can be used with all e-cig types. It enables generation of precisely controlled e-cig exposure while critical operational parameters and environmental mixing conditions can be adjusted in a systematic manner to assess their impact on complex chemistry and toxicity of emissions. Results proved the versatility and reproducibility of Ecig-EGS. E-cig emission was found to contain 106-107 particles/cm3 with the mode diameter around 200 nm, under air change rate of 60/h. Elevated CO2 and volatile organic specie generation was also observed. Furthermore, environmental mixing conditions also influenced e-cig emission profile. The versatility of Ecig-EGS will enable linking of operational and environmental parameters with exposure chemistry and toxicology and help in assessing health risks.

Basic science of electronic cigarettes: assessment in cell culture and in vivo models

Electronic cigarettes (e-cigarettes, ECIGs) were introduced into the market a decade ago as an alternative to tobacco smoking. Whether ECIGs are safe and whether they qualify as smoking cessation tool is currently unknown. Their use has markedly expanded in that period, despite the fact that potential toxic effects of the vapour created by the e-cigarette and the nicotine-containing cartridge fluid have been incompletely studied. Marketing targets diverse groups including older smokers but also young people. Whereas the adverse health effects of nicotine inhaled by users of ECIGs has been well documented, less is known about the other components. An increasing number of in vitro and in vivo studies demonstrate a range of adverse effects of both the vapour created by ECIGs as well as the nicotine-containing fluid. Importantly, these studies demonstrate that toxicity from ECIGs, although this may be less than that caused by tobacco products, not only arises from its nicotine content. Furthermore, there are no data on the long-term consequences of ECIG use. The wide range of ECIG products available to consumers and the lack of standardisation of toxicological approaches towards ECIG evaluation complicates the assessment of adverse health effects of their use. Here we review the current data on preclinical studies on ECIGs describing their effects in cell culture and animal models.

Occupational and Environmental Contributions to Chronic Cough in Adults: Chest Expert Panel Report

BACKGROUND

In response to occupational and environmental exposures, cough can be an isolated symptom reflecting exposure to an irritant with little physiological consequence, or it can be a manifestation of more significant disease. This document reviews occupational and environmental contributions to chronic cough in adults, focusing on aspects not previously covered in the 2006 ACCP Cough Guideline or our more recent systematic review, and suggests an approach to investigation of these factors when suspected.

METHODS

MEDLINE and TOXLINE literature searches were supplemented by articles identified by the cough panel occupational and environmental subgroup members, to identify occupational and environmental aspects of chronic cough not previously covered in the 2006 ACCP Cough Guideline. Based on the literature reviews and the Delphi methodology, the cough panel occupational and environmental subgroup developed guideline suggestions that were approved after review and voting by the full cough panel.

RESULTS

The literature review identified relevant articles regarding: mechanisms; allergic environmental causes; chronic cough and the recreational and involuntary inhalation of tobacco and marijuana smoke; nonallergic environmental triggers; laryngeal syndromes; and occupational diseases and exposures. Consensus-based statements were developed for the approach to diagnosis due to a lack of strong evidence from published literature.

CONCLUSIONS

Despite increased understanding of cough related to occupational and environmental triggers, there remains a gap between the recommended assessment of occupational and environmental causes of cough and the reported systematic assessment of these factors. There is a need for further documentation of occupational and environmental causes of cough in the future.

Nicotine exposure induces bronchial epithelial cell apoptosis and senescence via ROS mediated autophagy-impairment

Waterpipe smoking and e-cigarette vaping, the non-combustible sources of inhaled nicotine exposure are increasingly becoming popular and marketed as safer alternative to cigarette smoking. Hence, this study was designed to investigate the impact of inhaled nicotine exposure on disease causing COPD-emphysema mechanisms. For in vitro studies, human bronchial epithelial cells (Beas2b) were treated with waterpipe smoke extract (WPSE, 5%), nicotine (5mM), and/or cysteamine (250μM, an autophagy inducer and anti-oxidant drug), for 6hrs. We observed significantly (p<0.05) increased ubiquitinated protein-accumulation in the insoluble protein fractions of Beas2b cells treated with WPSE or nicotine that could be rescued by cysteamine treatment, suggesting aggresome-formation and autophagy-impairment. Moreover, our data also demonstrate that both WPSE and nicotine exposure significantly (p<0.05) elevates Ub-LC3β co-localization to aggresome-bodies while inducing Ub-p62 co-expression/accumulation, verifying autophagy-impairment. We also found that WPSE and nicotine exposure impacts Beas2b cell viability by significantly (p<0.05) inducing cellular apoptosis/senescence via ROS-activation, as it could be controlled by cysteamine, which is known to have an anti-oxidant property. For murine studies, C57BL/6 mice were administered with inhaled nicotine (intranasal, 500μg/mouse/day for 5 days), as an experimental model of non-combustible nicotine exposure. The inhaled nicotine exposure mediated oxidative-stress induces autophagy-impairment in the murine lungs as seen by significant (p<0.05, n=4) increase in the expression levels of nitrotyrosine protein-adduct (oxidative-stress marker, soluble-fraction) and Ub/p62/VCP (impaired-autophagy marker, insoluble-fraction). Overall, our data shows that nicotine, a common component of WPS, e-cigarette vapor and cigarette smoke, induces bronchial epithelial cell apoptosis and senescence via ROS mediated autophagy-impairment as a potential mechanism for COPD-emphysema pathogenesis.