Acute and chronic in vivo effects of exposure to nicotine and propylene glycol from an E-cigarette on mucociliary clearance in a murine model

The paradox of the safer cigarette: understanding the pulmonary effects of electronic cigarettes

Electronic cigarette (e-cigarette) use continues to rise globally. E-cigarettes have been presented as safer alternatives to combustion cigarettes that can mitigate the harm associated with tobacco products; however, the degree to which e-cigarette use itself can lead to morbidity and mortality is not fully defined. Herein we describe how e-cigarettes function; discuss the current knowledge of the effects of e-cigarette aerosol on lung cell cytotoxicity, inflammation, antipathogen immune response, mucociliary clearance, oxidative stress, DNA damage, carcinogenesis, matrix remodelling and airway hyperresponsiveness; and summarise the impact on lung diseases, including COPD, respiratory infection, lung cancer and asthma. We highlight how the inclusion of nicotine or flavouring compounds in e-liquids can impact lung toxicity. Finally, we consider the paradox of the safer cigarette: the toxicities of e-cigarettes that can mitigate their potential to serve as a harm reduction tool in the fight against traditional cigarettes, and we summarise the research needed in this underinvestigated area.

Impact of electronic cigarettes on pediatric, adolescent and young adult leukemia patients

Electronic cigarettes, which deliver an aerosolized, nicotine-containing product upon inhalation, are a public health issue that continue to gain popularity among adolescents and young adults in the United States. Use of electronic cigarettes is wide, and extends to pediatric patients with multiple comorbidities, including childhood cancer, leaving them vulnerable to further negative health outcomes. Acute leukemias are the most common type of cancer in pediatric populations, and treatment outcomes for these patients are improving; consequently, there is an increased emphasis on the effect of behavioral lifestyle factors on quality of life in survivorship. The rate of electronic cigarette use is higher among pediatric patients with a history of cancer than those without a history of cancer. Because electronic cigarettes are relatively new, much about their acute and long-term consequences remains unknown, as is their effect on therapy outcomes and long-term survivorship. This review article summarizes current knowledge about electronic cigarettes, including their composition and the trends in use among pediatric patients. Furthermore, this review provides a comprehensive description of the impact electronic cigarettes have on leukemia development, treatment and survivorship and highlights gaps in knowledge that will be necessary for developing recommendations, management strategies, and tailored treatments for pediatric leukemia patients and survivors who use these nicotine products.

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

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

Nicotine aerosols diminish airway CFTR function and mucociliary clearance

Electronic cigarettes (e-cigs) are often promoted as safe alternatives to smoking based on the faulty perception that inhaling nicotine is safe until other harmful chemicals in cigarette smoke are absent. Previously, others and we have reported that, similar to cigarette smoke, e-cig aerosols decrease CFTR-mediated ion transport across airway epithelium. However, it is unclear whether such defective epithelial ion transport by e-cig aerosols occurs in vivo and what the singular contribution of inhaled nicotine is to impairments in mucociliary clearance (MCC), the primary physiologic defense of the airways. Here, we tested the effects of nicotine aerosols from e-cigs in primary human bronchial epithelial (HBE) cells and two animal models, rats and ferrets, known for their increasing physiologic complexity and potential for clinical translation, followed by in vitro and in vivo electrophysiologic assays for CFTR activity and micro-optical coherence tomography (μOCT) image analyses for alterations in airway mucus physiology. Data presented in this report indicate nicotine in e-cig aerosols causes 1) reduced CFTR and epithelial Na+ channel (ENaC)-mediated ion transport, 2) delayed MCC, and 3) diminished airway surface hydration, as determined by periciliary liquid depth analysis. Interestingly, the common e-cig vehicles vegetable glycerin and propylene glycol did not affect CFTR function or MCC in vivo despite their significant adverse effects in vitro. Overall, our studies contribute to an improved understanding of inhaled nicotine effects on lung health among e-cig users and inform pathologic mechanisms involved in altered host defense and increased risk for tobacco-associated lung diseases.

E-cigarette vapor exposure in utero causes long-term pulmonary effects in offspring

The in utero environment is sensitive to toxicant exposure, altering the health and growth of the fetus, and thus sensitive to contaminant exposure. Though recent clinical data suggest that e-cigarette use does no further harm to birth outcomes than a nicotine patch, this does not account for the effects of vaping during pregnancy on the long-term health of offspring. Pregnant mice were exposed to: 1) e-cigarette vapor with nicotine (PV + Nic; 2% Nic in 50:50 propylene glycol: vegetable glycerin), 2) e-cigarette vapor without nicotine [PV; (50:50 propylene glycol:vegetable glycerin)], or 3) HEPA filtered air (FA). Dams were removed from exposure upon giving birth. At 5 mo of age, pulmonary function tests on the offspring revealed female and male mice from the PV group had greater lung stiffness (Ers) and alveolar stiffness (H) compared with the FA group. Furthermore, baseline compliance (Crs) was reduced in female mice from the PV group and in male mice from the PV and PV + Nic groups. Lastly, female mice had decreased forced expiratory volume (FEV0.1) in the PV group, but not in the male groups, compared with the FA group. Lung histology revealed increased collagen deposition around the vessels/airways and in alveolar tissue in PV and PV + Nic groups. Furthermore, goblet hyperplasia was observed in PV male and PV/PV + Nic female mice. Our work shows that in utero exposure to e-cigarette vapor, regardless of nicotine presence, causes lung dysfunction and structural impairments that persist in the offspring to adulthood.

E-cigarettes and Vaping: A Smoking Cessation Method or Another Smoking Innovation?

The prevalence of using e-cigarettes (vaping) has risen rapidly since its introduction in 2007, mostly among male youth. Although research on the health risks of e-cigarettes is still limited, there is growing evidence of debilitating pulmonary conditions and general immune weakness from e-cigarettes, leading to various infections. Moreover, there are concerns that vaping could be used as a new model of cannabis consumption, increasing cannabis addiction among adolescents. With well-known health risks from traditional smoking, e-cigarettes are viewed as a safe way of smoking, appealing more to youth. Additionally, extensive e-cigarette marketing boosted by the internet and fame has resulted in worries that e-cigarettes can lead to a renormalization of cigarette smoking and can be used as a new method to consume vaporized drugs. Although the concern that e-cigarettes are as harmful as traditional smoking has been raised, youth and most healthcare providers remain relatively unaware. Therefore, this review explored the association between e-cigarettes and traditional smoking. With the introduction of e-cigarettes in the last two decades, the topic is still new and less studied. Therefore, this review will help us understand the topic to better care for e-cigarette smokers and reduce the increasing public health burden from vaping.

Impact of vaping on respiratory health

Widespread uptake of vaping has signaled a sea change in the future of nicotine consumption. Vaping has grown in popularity over the past decade, in part propelled by innovations in vape pen design and nicotine flavoring. Teens and young adults have seen the biggest uptake in use of vape pens, which have superseded conventional cigarettes as the preferred modality of nicotine consumption. Relatively little is known, however, about the potential effects of chronic vaping on the respiratory system. Further, the role of vaping as a tool of smoking cessation and tobacco harm reduction remains controversial. The 2019 E-cigarette or Vaping Use-Associated Lung Injury (EVALI) outbreak highlighted the potential harms of vaping, and the consequences of long term use remain unknown. Here, we review the growing body of literature investigating the impacts of vaping on respiratory health. We review the clinical manifestations of vaping related lung injury, including the EVALI outbreak, as well as the effects of chronic vaping on respiratory health and covid-19 outcomes. We conclude that vaping is not without risk, and that further investigation is required to establish clear public policy guidance and regulation.

Developmental Effects of Electronic Cigarette Use

Electronic cigarettes have gained widespread acceptance among adolescents and young adults. As a result of this popularity, there are concerns regarding the potential harm of primary, secondhand and thirdhand electronic cigarette exposures on fetal and postnatal development. In vitro studies have shown that constituents in electronic cigarette liquids, including nicotine, flavorings, and carrier agents can alter cellular processes and growth. Additionally, aerosolized electronic cigarette emissions have been shown to disrupt organ development and immune responses in preclinical studies. In clinical studies, an association between electronic cigarette use and frequent respiratory symptoms, greater asthma severity and impaired mucociliary clearance has been demonstrated with adolescent and young adult users of electronic cigarettes having twice the frequency of cough, mucus production, or bronchitis compared to nonusers. Along with the popularity of electronic cigarette use, secondhand electronic cigarette exposure has increased substantially; with almost one-fourth of middle and high school children reporting exposure to secondhand vapors. The health consequences of secondhand electronic cigarette exposure on children and other vulnerable populations are poorly understood but detectable levels of cotinine have been measured in nonusers. Pregnant women and their offspring are another vulnerable group at increased risk for health consequences from electronic cigarette exposure. Nicotine crosses the placenta and can disrupt brain and lung development in preclinical studies. This article will focus on the physiological and health effects associated with primary or secondhand exposure to electronic cigarettes. It is expected that with ongoing availability of electronic cigarettes as well as the accumulation of additional follow-up time for long-term outcomes, the risks associated with exposure will become better clarified. © 2022 American Physiological Society. Compr Physiol 12:3337-3346, 2022.

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

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

Comparison of the in vivo genotoxicity of electronic and conventional cigarettes aerosols after subacute, subchronic and chronic exposures

Tobacco smoking is classified as a human carcinogen. A wide variety of new products, in particular electronic cigarettes (e-cigs), have recently appeared on the market as an alternative to smoking. Although the in vitro toxicity of e-cigs is relatively well known, there is currently a lack of data on their long-term health effects. In this context, the aim of our study was to compare, on a mouse model and using a nose-only exposure system, the in vivo genotoxic and mutagenic potential of e-cig aerosols tested at two power settings (18 W and 30 W) and conventional cigarette (3R4F) smoke. The standard comet assay, micronucleus test and Pig-a gene mutation assay were performed after subacute (4 days), subchronic (3 months) and chronic (6 months) exposure. The generation of oxidative stress was also assessed by measuring the 8-hydroxy-2'-deoxyguanosine and by using the hOGG1-modified comet assay. Our results show that only the high-power e-cig and the 3R4F cigarette induced oxidative DNA damage in the lung and the liver of exposed mice. In return, no significant increase in chromosomal aberrations or gene mutations were noted whatever the type of product. This study demonstrates that e-cigs, at high-power setting, should be considered, contrary to popular belief, as hazardous products in terms of genotoxicity in mouse model.

Effect of Puffing Behavior on Particle Size Distributions and Respiratory Depositions From Pod-Style Electronic Cigarette, or Vaping, Products

The current fourth generation ("pod-style") electronic cigarette, or vaping, products (EVPs) heat a liquid ("e-liquid") contained in a reservoir ("pod") using a battery-powered coil to deliver aerosol into the lungs. A portion of inhaled EVP aerosol is estimated as exhaled, which can present a potential secondhand exposure risk to bystanders. The effects of modifiable factors using either a prefilled disposable or refillable pod-style EVPs on aerosol particle size distribution (PSD) and its respiratory deposition are poorly understood. In this study, the influence of up to six puff profiles (55-, 65-, and 75-ml puff volumes per 6.5 and 7.5 W EVP power settings) on PSD was evaluated using a popular pod-style EVP (JUUL® brand) and a cascade impactor. JUUL® brand EVPs were used to aerosolize the manufacturers' e-liquids in their disposable pods and laboratory prepared "reference e-liquid" (without flavorings or nicotine) in refillable pods. The modeled dosimetry and calculated aerosol mass median aerodynamic diameters (MMADs) were used to estimate regional respiratory deposition. From these results, exhaled fraction of EVP aerosols was calculated as a surrogate of the secondhand exposure potential. Overall, MMADs did not differ among puff profiles, except for 55- and 75-ml volumes at 7.5 W (p < 0.05). For the reference e-liquid, MMADs ranged from 1.02 to 1.23 μm and dosimetry calculations predicted that particles would deposit in the head region (36-41%), in the trachea-bronchial (TB) region (19-21%), and in the pulmonary region (40-43%). For commercial JUUL® e-liquids, MMADs ranged from 0.92 to 1.67 μm and modeling predicted that more particles would deposit in the head region (35-52%) and in the pulmonary region (30-42%). Overall, 30-40% of the particles aerosolized by a pod-style EVP were estimated to deposit in the pulmonary region and 50-70% of the inhaled EVP aerosols could be exhaled; the latter could present an inhalational hazard to bystanders in indoor occupational settings. More research is needed to understand the influence of other modifiable factors on PSD and exposure potential.

E-Cigarette Use: Device Market, Study Design, and Emerging Evidence of Biological Consequences

Electronic cigarettes are frequently viewed as a safer alternative to conventional cigarettes; however, evidence to support this perspective has not materialized. Indeed, the current literature reports that electronic cigarette use is associated with both acute lung injury and subclinical dysfunction to the lung and vasculature that may result in pathology following chronic use. E-cigarettes can alter vascular dynamics, polarize innate immune populations towards a proinflammatory state, compromise barrier function in the pulmonary endothelium and epithelium, and promote pre-oncogenic phenomena. This review will summarize the variety of e-cigarette products available to users, discuss current challenges in e-cigarette study design, outline the range of pathologies occurring in cases of e-cigarette associated acute lung injury, highlight disease supporting tissue- and cellular-level changes resulting from e-cigarette exposure, and briefly examine how these changes may promote tumorigenesis. Continued research of the mechanisms by which e-cigarettes induce pathology benefit users and clinicians by resulting in increased regulation of vaping devices, informing treatments for emerging diseases e-cigarettes produce, and increasing public awareness to reduce e-cigarette use and the onset of preventable disease.

The effect of ingredients commonly used in nasal and inhaled solutions on the secretion of mucus in vitro

Hypersecretion of mucus is associated with impaired mucociliary clearance that can influence the retention of active pharmaceutical ingredients in the airway but is also linked with recurrent airway disease. Therefore, the effect on mucin secretion of a range of ingredients used in solutions delivered to the nose and lung was studied. Mucin secretion from explants of ovine epithelium was quantified using an enzyme-linked lectin assay (ELLA) or sandwich ELLA depending on the compatibility of the ingredients with the assay. Benzalkonium chloride (0.015% w/w), Methocel™ E50 premium LV (1.0% w/w), propylene glycol (1.5% w/w), potassium sorbate + propylene glycol (0.3% w/w + 1.5% w/w) and polysorbate 80 (0.025% w/w), used at common working concentrations, all increased the secretion of mucin from the explants (P < 0.05). Ethylenediamine tetraacetic acid-disodium salt (EDTA) (0.015% w/w), Avicel® RC591 (1.5% w/w), fluticasone furoate (0.0004% w/w, concentration in solution) and dimethyl sulfoxide (DMSO) (0.2% w/w) did not affect mucin secretion. Compounds increasing mucin secretion could alter the rate of mucociliary clearance and the mucus could provide a barrier to drug absorption. This could predispose patients to disease and affect the activity of delivered drugs, decreasing or increasing their clinical efficacy.

The chemistry and toxicology of vaping

Vaping is the process of inhaling and exhaling an aerosol produced by an e-cigarette, vape pen, or personal aerosolizer. When the device contains nicotine, the Food and Drug Administration (FDA) lists the product as an electronic nicotine delivery system or ENDS device. Similar electronic devices can be used to vape cannabis extracts. Over the past decade, the vaping market has increased exponentially, raising health concerns over the number of people exposed and a nationwide outbreak of cases of severe, sometimes fatal, lung dysfunction that arose suddenly in otherwise healthy individuals. In this review, we discuss the various vaping technologies, which are remarkably diverse, and summarize the use prevalence in the U.S. over time by youths and adults. We examine the complex chemistry of vape carrier solvents, flavoring chemicals, and transformation products. We review the health effects from epidemiological and laboratory studies and, finally, discuss the proposed mechanisms underlying some of these health effects. We conclude that since much of the research in this area is recent and vaping technologies are dynamic, our understanding of the health effects is insufficient. With the rapid growth of ENDS use, consumers and regulatory bodies need a better understanding of constituent-dependent toxicity to guide product use and regulatory decisions.

Impact of exclusive e-cigarettes and heated tobacco products use on muco-ciliary clearance

Background:

Tobacco smoking impairs mucociliary clearance (MCC) efficiency as shown by prolonged saccharin test transit time (STTT). Avoiding exposure to tobacco smoke from combustible cigarettes may restore MCC function and former smokers have been shown to exhibit similar STTT as never smokers. The impact on STTT of switching from smoking to combustion-free tobacco products such as e-cigarettes (ECs) and heated tobacco products (HTPs) is not known.

Methods:

We report STTT of exclusive EC and HTP users. Test results were compared with those obtained in current, former, and never smokers.

Results:

STTT were obtained from 39 current, 40 former, 40 never smokers, and from 20 EC and 20 HTP users. Comparison of STTT values showed significant difference among the five study groups (p < 0.00001) with current smokers having a median [interquartile range (IQR)] STTT of 13.15 min, which was significantly longer compared with that of all other study groups. In particular, compared with former (7.26 min) and never smokers (7.24 min), exclusive EC users and exclusive HTP users had similar STTT at 7.00 and 8.00 min, respectively.

Conclusion:

Former smokers who have switched to exclusive regular use of combustion-free nicotine delivery systems (i.e., ECs and HTPs) exhibit similar saccharin transit time as never and former smokers. This suggests that combustion-free nicotine delivery technologies are unlikely to have detrimental effects on MCC function.

Nicotine-free vapor inhalation produces behavioral disruptions and anxiety-like behaviors in mice: Effects of puff duration, session length, sex, and flavor

Electronic-cigarette's (ECIGs) popularity has grown over the last decade and changed the way individuals administer nicotine. Preclinical research is imperative for understanding the addictive properties and health-risks associated with ECIG use; however, there is not a standard dosing regimen used across research laboratories. The main objective was to determine how vapor puff durations, administration session length, and flavored e-liquid alter general and mood-disorder related behaviors while providing a foundation of vapor administration parameters. Adult male and female C57BL/6 mice were exposed to several nicotine-free unflavored vapor puff durations (1, 3, 6, or 10 s) and vapor administration session lengths (10 and 30 min) then measured on the following assays: locomotor activity (LMA), tail suspension test (TST), and light-dark test. The effects of mecamylamine and the time-course of vapor-induced depression of LMA also were assessed. Additionally, mice were exposed to flavored (strawberry and adventurers tobacco blend) vapor inhalation and measured on locomotor activity, tail suspension test, and light-dark test. Following both 10 and 30 min vapor administration session, there was a puff duration-dependent decrease in distance traveled, time in center, and rearing. The vapor-induced depression of LMA was not mediated by nicotine or nicotinic acetylcholine receptor (nAChR) activation and lasted 60-90 min. The 10 s puff duration produced an anxiogenic-like effect in the light-dark test by decreasing the time spent in the light side. Vapor inhalation did not significantly alter TST behavior. No significant effects of sex or flavor were found. The anxiogenic-like effects of nicotine-free vapor inhalation are concerning as many adolescents vape nicotine-free flavored e-liquid, and there is an association between ECIGs and mood disorders. Additionally, these studies demonstrate that vapor puff duration, but not vapor administration session length, is an important variable to consider during research design as it can become a confounding variable and alter baseline behaviors.

Acute e-cig inhalation impacts vascular health: a study in smoking naïve subjects

This study was designed to investigate the acute effects of nonnicotinized e-cigarette (e-cig) aerosol inhalation in nonsmokers both in terms of blood-based markers of inflammation and oxidative stress and evaluate their association with hemodynamic-metabolic MRI parameters quantifying peripheral vascular reactivity, cerebrovascular reactivity, and aortic stiffness. Thirty-one healthy nonsmokers were subjected to two blood draws and two identical MRI protocols, each one before and after a standardized e-cig vaping session. After vaping, the serum levels of C-reactive protein, soluble intercellular adhesion molecule, and the danger signal machinery high-mobility group box 1 (HMGB1) and its downstream effector and the NLR family pyrin domain containing 3 (NLRP3) inflammasome (as monitored by its adaptor protein ASC) increased significantly relative to the respective baseline (prevaping) values. Moreover, nitric oxide metabolites and reactive oxygen species production decreased and increased, respectively. These observations were paralleled by impaired peripheral vascular reactivity (with reduced flow-mediated dilation and attenuated hyperemic response after a cuff-occlusion test) and metabolic alterations expressed by decreased venous oxygen saturation, postvaping. The current results suggest propagation of inflammation signaling via activation of the danger signaling axis (HMGB1-NLRP3). The findings indicate that a single episode of vaping has adverse impacts on vascular inflammation and function.NEW & NOTWORTHY Endothelial cell signaling and blood biomarkers were found to correlate with functional vascular changes in a single episode e-cigarettes inhalation in healthy adults. This is indicative of the potential of e-cigarettes (even when inhaled acutely) to lead of vascular dysfunction.

Changes in Multiple and Different Tobacco Product Use Behaviors in Women Before and During Pregnancy: An Analysis of Longitudinal Population Assessment of Tobacco and Health Data

INTRODUCTION

Changes in tobacco use behaviors among women with respect to pregnancy are expected to be significant and dynamic, with a strong desire for smoking cessation, diversification of tobacco products, and perceived relative safety on noncigarette tobacco products. This study aims to illustrate how multiple and different tobacco use behaviors change before and during pregnancy.

METHODS

Data were extracted from 864 pregnant, nationally representative U.S. women, who were prospectively followed with the Population Assessment of Tobacco and Health study between 2013 and 2017. Smoking statuses were defined on the basis of the number and type of 7 different tobacco products under current use. Differences in maternal characteristics were investigated in relation to tobacco cessation statuses during pregnancy. Weighted percentages and 95% CIs were calculated.

RESULTS

Only 50.4% of prepregnancy tobacco users achieved complete abstinence with varying rates of cessation, depending on the number and type of products used prepregnancy. The lowest cessation rates were observed among prepregnancy poly-tobacco users (23.3%) and conventional cigarette smokers (45.5%). During pregnancy, 11.3% and 2.8% of women reported smoking cigarettes and e-cigarettes, respectively. Persistent tobacco users during pregnancy were more likely to be white, be older, and have nonprivate or no medical insurance (all p<0.05).

CONCLUSIONS

This study demonstrates a widespread prenatal tobacco use and low rates of complete cessation in major subgroups of tobacco users. Current findings on the concurrent use of multiple products and noncigarette tobacco products highlight the urgent need for further research and comprehensive public health intervention for smoking cessation during pregnancy.

The fog, the attractive and the addictive: pulmonary effects of vaping with a focus on the contribution of each major vaping liquid constituent

Vaping has become increasingly popular over the past decade. This pragmatic review presents the published biological effects of electronic cigarette vapour inhalation with a focus on the pulmonary effects. Special attention has been devoted to providing the documented effects specific to each major ingredient, namely propylene glycol/glycerol, nicotine and flavouring agents. For each ingredient, findings are divided according to the methodology used, being in vitro studies, animal studies and clinical studies. Finally, we provide thoughts and insights on the current state of understanding of the pulmonary effects of vaping, as well as novel research avenues and methodologies.

Electronic cigarettes may not be a "safer alternative" of conventional cigarettes during pregnancy: evidence from the nationally representative PRAMS data

Background

Conventional cigarette (CC) smoking is one of the most preventable causes of adverse birth outcomes. Although electronic cigarettes (ECs) are considered to be safer than CCs during pregnancy, the evidence is yet to be presented. This study examines the effects of prenatal EC use on neonatal birth outcomes compared to those of CC smokers and complete tobacco abstainers.

Methods

Data was extracted from 55,251 pregnant women who participated in the Phase 8 survey of the Pregnancy Risk Assessment Monitoring System between 2016 and 2018. Participants were classified into three groups based on their smoking behaviors in the third trimester: complete tobacco abstinence, exclusive CC smoking, or exclusive EC use. Adverse outcomes included infants being small-for-gestational-age (SGA), having low birthweight (LBW), and being born at preterm. EC users were matched to complete abstainers and CC smokers who share the same baseline characteristics in race/ethnicity, age, educational attainment, income, prenatal care adequacy, and first- and second-trimester CC smoking statuses. The association between EC use and adverse birth outcomes were examined by survey-weighted logistic regression analyses in the matched population.

Results

Among participants, 1.0% of women reported having used ECs during the third trimester, 60% of which reported using ECs exclusively. Neonates of EC users were significantly more likely to be SGA (OR 1.76; 95% CI 1.04, 2.96), have LBW (OR 1.53; 95% CI 1.06, 2.22), or be born preterm (OR 1.86; 95% CI 1.11, 3.12) compared to tobacco abstainers. However, odds of EC users’ pregnancies resulting in SGA (OR 0.67; 95% CI 0.30, 1.47), LBW (OR 0.71; 95% CI 0.37, 1.37), or preterm birth (OR 1.06; 95% CI 0.46, 2.48) were not significantly lower than those of CC smokers.

Conclusions

Even after accounting for shared risk factors between prenatal tobacco use and adverse birth outcomes, EC use remains an independent risk factor for neonatal complications and is not a safer alternative to CC smoking during pregnancy. Until further research is completed, all pregnant women are encouraged to abstain from all tobacco products including ECs.

Effect of sub-chronic exposure to cigarette smoke, electronic cigarette and waterpipe on human lung epithelial barrier function

BACKGROUND

Taking into consideration a recent surge of a lung injury condition associated with electronic cigarette use, we devised an in vitro model of sub-chronic exposure of human bronchial epithelial cells (HBECs) in air-liquid interface, to determine deterioration of epithelial cell barrier from sub-chronic exposure to cigarette smoke (CS), e-cigarette aerosol (EC), and tobacco waterpipe exposures (TW).

METHODS

Products analyzed include commercially available e-liquid, with 0% or 1.2% concentration of nicotine, tobacco blend (shisha), and reference-grade cigarette (3R4F). In one set of experiments, HBECs were exposed to EC (0 and 1.2%), CS or control air for 10 days using 1 cigarette/day. In the second set of experiments, exposure of pseudostratified primary epithelial tissue to TW or control air exposure was performed 1-h/day, every other day, until 3 exposures were performed. After 16-18 h of last exposure, we investigated barrier function/structural integrity of the epithelial monolayer with fluorescein isothiocyanate-dextran flux assay (FITC-Dextran), measurements of trans-electrical epithelial resistance (TEER), assessment of the percentage of moving cilia, cilia beat frequency (CBF), cell motion, and quantification of E-cadherin gene expression by reverse-transcription quantitative polymerase chain reaction (RT-qPCR).

RESULTS

When compared to air control, CS increased fluorescence (FITC-Dextran assay) by 5.6 times, whereby CS and EC (1.2%) reduced TEER to 49 and 60% respectively. CS and EC (1.2%) exposure reduced CBF to 62 and 59%, and cilia moving to 47 and 52%, respectively, when compared to control air. CS and EC (1.2%) increased cell velocity compared to air control by 2.5 and 2.6 times, respectively. The expression of E-cadherin reduced to 39% of control air levels by CS exposure shows an insight into a plausible molecular mechanism. Altogether, EC (0%) and TW exposures resulted in more moderate decreases in epithelial integrity, while EC (1.2%) substantially decreased airway epithelial barrier function comparable with CS exposure.

CONCLUSIONS

The results support a toxic effect of sub-chronic exposure to EC (1.2%) as evident by disruption of the bronchial epithelial cell barrier integrity, whereas further research is needed to address the molecular mechanism of this observation as well as TW and EC (0%) toxicity in chronic exposures.

How bad are e-cigarettes? What can we learn from animal exposure models?

Electronic cigarettes divide opinions. Some consider them key to reducing smoking incidence while others are concerned over potential for detrimental health consequences. It will take many years to identify the health consequences of e-cigarette use if we rely only upon human data. However, there is a growing body of work using rodent models that inform on these potential toxicities. These studies have focused upon the pulmonary, cardiovascular and central nervous systems. Observations include perturbations of pro-inflammatory, pro-fibrotic and oxidative stress markers, sometimes together with DNA damage and downregulation of DNA repair and antioxidant enzymes. However, the markers affected are often different between studies. A more consistent observation has been the increase in airway hyperresponsiveness, a characteristic of asthma, on exposure to electronic cigarettes, across mouse strains, sex and ages. Detrimental effects in this and other susceptible animal models such as the apolipoprotein E knock-out mouse model of atherosclerosis, suggest greater risk where there is an existing predisposition. Other adverse reactions, including weight loss, oxidative stress and angiogenesis, are reported in animal studies with nicotine-containing devices. These effects remain less severe than cigarette smoke, where investigated. Animal studies have identified therefore that e-cigarettes are potentially hazardous, especially in susceptible populations, nicotine is integral to risk of health effects, but overall e-cigarettes are much less hazardous than cigarettes.

Recent findings in the pharmacology of inhaled nicotine: Preclinical and clinical in vivo studies

INTRODUCTION

The rise of vaping in adolescents, the recent entrance of new inhaled nicotine products such as iQOS on the market and e-cigarette or vaping product use-associated lung injury cases has created concern for the use of inhaled non-combustible nicotine products. This narrative review discusses recent experimental in vivo studies that utilize human, rat and mouse models to understand the pharmacological impact of nicotine from non-combustible products.

METHODS

The search engine PubMed was utilized with the following search terms: inhaled nicotine, nicotine e-cigarette, heated tobacco products, iQOS, electronic cigarette, nicotine inhaler, nicotine vaping. This review highlights recent primary in vivo studies of inhaled nicotine administration experimental paradigms that occurred in laboratory settings using human and rodent (rats and mice) models that have been published from January 2017-December 2019.

RESULTS

The pharmacokinetics of nicotine via e-cigarettes is influenced by the PG/VG and flavor constituents in e-liquids, the presence of nicotine salts in e-liquids, puff topography of nicotine and tobacco product users and the power of the e-cigarette device. The pharmacodynamic impact of inhaled nicotine has cardiovascular, pulmonary and central nervous system implications.

CONCLUSION

The articles reviewed here highlight the importance of both animal and human models to fully understand the impact of inhaled nicotine pharmacology There is a need for more rodent pharmacokinetic inhaled nicotine studies to understand the influences of factors such as flavor and nicotine salts. Additionally, consensus on nicotine measurement in both human and rodent studies is greatly needed.

Vaping-Related Acute Parenchymal Lung Injury: A Systematic Review

The outbreak of vaping-related acute lung injury in the United States, named EVALI (e-cigarette or vaping product use associated acute lung injury), has reignited concerns about the health effects of vaping. Initial case reports of vaping-related lung injury date back to 2012, but the ongoing outbreak of EVALI began in the summer of 2019 and has been implicated in 2,807 cases and 68 deaths as of this writing. Review of the scientific literature revealed 216 patient cases that spanned 41 reports of parenchymal lung injury attributed to vaping. In this review, we detail the clinical, radiographic, and pathologic patterns of lung injury that are attributable to vaping and provide an overview of the scientific literature to date on the effects of vaping on respiratory health. Tetrahydrocannabinol was the most commonly vaped substance, and vitamin E acetate was found in BAL specimens from many affected individuals. However, no specific component or contaminant has been identified conclusively to date as the cause for the injury. Patients present with cough, dyspnea, constitutional symptoms, and GI symptoms. Radiologic and histopathologic findings demonstrate a spectrum of nonspecific acute injury patterns. A high index of suspicion combined with a good history are the keys to an accurate diagnosis. Treatment is supportive; the mortality rate is low, and most patients recover. Corticosteroids have been used with apparent success in patients with severe disease, but more rigorous studies are needed to clarify their role in the treatment of vaping-related lung injury.

Anaerobic Necrotizing Pneumonia: Another Potential Life-threatening Complication of Vaping?

An adolescent girl with a history of frequent electronic cigarette use of nicotine was hospitalized with severe necrotizing pneumonia. Blood cultures obtained before the administration of empirical broad-spectrum intravenous antibiotics had positive results for the growth of Fusobacterium necrophorum The pathogen is an uncommon but well-known cause of anaerobic pneumonia with unique features that are collectively referred to as Lemierre syndrome or postanginal sepsis. The syndrome begins as a pharyngeal infection. Untreated, the infection progresses to involve the ipsilateral internal jugular vein, resulting in septic thrombophlebitis with direct spread from the neck to the lungs causing multifocal necrotizing pneumonia. The teenager we present in this report had neither a preceding pharyngeal infection nor Doppler ultrasonographic evidence for the presence of deep neck vein thrombi, leading us to explore alternative mechanisms for her pneumonia. We propose the possibility that her behavior of frequent vaping led to sufficient pharyngeal irritation such that F necrophorum colonizing her oropharynx was inhaled directly into her lungs during electronic cigarette use. Preexisting, but not yet recognized, vaping-related lung injury may have also contributed to her risk of developing the infection. The patient was hospitalized for 10 days. At follow-up one month later, she still became short of breath with minimal exertion.

The Effects of Nicotine on Development

Recently, there has been a significant increase in the use of noncombustible nicotine-containing products, including electronic cigarettes (e-cigarettes). Of increasing popularity are e-cigarettes that can deliver high doses of nicotine over short periods of time. These devices have led to a rise in nicotine addiction in adolescent users who were nonsmokers. Use of noncombustible nicotine products by pregnant mothers is also increasing and can expose the developing fetus to nicotine, a known teratogen. In addition, young children are frequently exposed to secondhand and thirdhand nicotine aerosols generated by e-cigarettes, with little understanding of the effects these exposures can have on health. With the advent of these new nicotine-delivery systems, many concerns have arisen regarding the short- and long-term health effects of nicotine on childhood health during all stages of development. Although health studies on nicotine exposure alone are limited, educating policy makers and health care providers on the potential health effects of noncombustible nicotine is needed because public acceptance of these products has become so widespread. Most studies evaluating the effects of nicotine on health have been undertaken in the context of smoke exposure. Nevertheless, in vitro and in vivo preclinical studies strongly indicate that nicotine exposure alone can adversely affect the nervous, respiratory, immune, and cardiovascular systems, particularly when exposure occurs during critical developmental periods. In this review, we have included both preclinical and clinical studies to identify age-related health effects of nicotine exposure alone, examining the mechanisms underlying these effects.

Smoking and pregnancy: The era of electronic nicotine delivery systems

Electronic nicotine delivery systems have been commercially available in the United States since 2007. Despite a decrease in combustible cigarette use, electronic nicotine delivery systems use has dramatically increased among both adults and adolescents. These devices have been marketed as smoking cessation aids, although data on their efficacy are scarce. Pregnant women are an especially vulnerable population susceptible to claims of safety and efficacy, and the medical community remains inadequately informed on how to counsel these women. The purpose of this article is to review known literature regarding the use of electronic nicotine delivery systems in pregnancy, to understand the differences between cigarettes and electronic nicotine delivery systems use in pregnancy, and to further guide clinicians on how to advise the pregnant woman on their use.

A custom-built low-cost chamber for exposing rodents to e-cigarette aerosol: practical considerations

Objectives: To (1) design and build a low-cost exposure chamber system for whole-body exposure of rodents to electronic cigarette aerosol, (2) provide detailed instructions with particular focus on automated e-cigarette activation, and (3) develop a simple mathematical model for aerosol levels in the exposure chamber.Methods: We built the system with standard laboratory equipment and an open-source electronics platform (Arduino) for e-cigarette activation. Arduino is used to control a solenoid, which pushes the activation button of so-called "Mod" e-cigarettes, and a pump to move the aerosol from the mouthpiece of the e-cigarette into the chamber. For "Pods" and "Cigalikes," the solenoid is not used as they are activated by the vacuum created by the pump. Aerosol concentrations were measured with a light-scattering laser photometer.Results: The system allows varying the air exchange rate, monitoring aerosol levels, and programing arbitrary puff topography. Aerosol concentrations observed for different chamber operating conditions (puff time and period, e-cigarette power output, air exchange rate) were consistent with the mathematical model.Conclusions: Our low-cost exposure chamber can be used in animal experimental studies of the health effects of e-cigarettes. Our model allows estimating design parameters such as chamber volume, air exchange rate, and puff period.

Electronic Cigarette Vapor with Nicotine Causes Airway Mucociliary Dysfunction Preferentially via TRPA1 Receptors

Rationale: Electronic cigarette (e-cig) use has been widely adopted under the perception of safety. However, possibly adverse effects of e-cig vapor in never-smokers are not well understood.Objectives: To test the effects of nicotine-containing e-cig vapors on airway mucociliary function in differentiated human bronchial epithelial cells isolated from never-smokers and in the airways of a novel, ovine large animal model.Methods: Mucociliary parameters were measured in human bronchial epithelial cells and in sheep. Systemic nicotine delivery to sheep was quantified using plasma cotinine levels, measured by ELISA.Measurements and Main Results:In vitro, exposure to e-cig vapor reduced airway surface liquid hydration and increased mucus viscosity of human bronchial epithelial cells in a nicotine-dependent manner. Acute nicotine exposure increased intracellular calcium levels, an effect primarily dependent on TRPA1 (transient receptor potential ankyrin 1). TRPA1 inhibition with A967079 restored nicotine-mediated impairment of mucociliary parameters including mucus transport in vitro. Sheep tracheal mucus velocity, an in vivo measure of mucociliary clearance, was also reduced by e-cig vapor. Nebulized e-cig liquid containing nicotine also reduced tracheal mucus velocity in a dose-dependent manner and elevated plasma cotinine levels. Importantly, nebulized A967079 reversed the effects of e-cig liquid on sheep tracheal mucus velocity.Conclusions: Our findings show that inhalation of e-cig vapor causes airway mucociliary dysfunction in vitro and in vivo. Furthermore, they suggest that the main nicotine effect on mucociliary function is mediated by TRPA1 and not nicotinic acetylcholine receptors.

E-cigarette use increases susceptibility to bacterial infection by impairment of human neutrophil chemotaxis, phagocytosis, and NET formation

E-cigarettes are portrayed as safer relative to conventional tobacco. However, burgeoning evidence suggests that E-cigarettes may adversely affect host defenses. However, the precise mechanisms by which E-cigarette vapor alters innate immune cell function have not been fully elucidated. We determined the effects of E-cigarette exposure on the function and responses to infectious challenge of the most abundant innate immune cell, the neutrophil, using isolated human neutrophils and a mouse model of gram-negative infection. Our results revealed that human neutrophils exposed to E-cigarette vapor had 4.2-fold reductions in chemotaxis toward the bacterial cell-well component f-Met-Leu-Phe (P < 0.001). F-actin polarization and membrane fluidity were also adversely affected by E-cigarette vapor exposure. E-cigarette-exposed human neutrophils exhibited a 48% reduction in production of reactive oxygen species (ROS; P < 0.001). Given the central role of ROS in neutrophil extracellular trap (NET) production, NET production was quantified, and E-cigarette vapor exposure was found to reduce NETosis by 3.5-fold (P < 0.01); formulations with and without nicotine containing propylene glycol exhibiting significant suppressive effects. However, noncanonical NETosis was unaffected. In addition, exposure to E-cigarette vapor lowered the rate of phagocytosis of bacterial bioparticles by 47% (P < 0.05). In our physiological mouse model of chronic E-cigarette exposure and sepsis, E-cigarette vapor inhalation led to reduced neutrophil migration in infected spaces and a higher burden of Pseudomonas. These findings provide evidence that E-cigarette use adversely impacts the innate immune system and may place E-cigarette users at higher risk for dysregulated inflammatory responses and invasive bacterial infections.

Dysregulated repair and inflammatory responses by e-cigarette-derived inhaled nicotine and humectant propylene glycol in a sex-dependent manner in mouse lung

Nicotine inhalation via electronic cigarettes (e‐cigs) is an emerging concern. However, little is known about the acute toxicity in the lungs following inhalation of nicotine‐containing e‐cig aerosols. We hypothesized that acute exposure to aerosolized nicotine causes lung toxicity by eliciting inflammatory and dysregulated repair responses. Adult C57BL/6J mice were exposed 2 hours daily for 3 days to e‐cig aerosols containing propylene glycol (PG) with or without nicotine. Acute exposure to nicotine‐containing e‐cig aerosols induced inflammatory cell influx (neutrophils and CD8a⁺ T lymphocytes), and release of pro‐inflammatory cytokines in bronchoalveolar lavage fluid in a sex‐dependent manner. Inhalation of e‐cig aerosol containing PG alone significantly augmented the lung levels of various homeostasis/repair mediators (PPARγ, ADRP, ACTA2, CTNNB1, LEF1, β‐catenin, E‐cadherin, and MMP2) in a sex‐dependent manner when compared to air controls. These findings were accompanied by an increase in protein abundance and altered gene expression of lipogenic markers (PPARγ, ADRP) and myogenic markers (fibronectin, α‐smooth muscle actin and β‐catenin), suggesting a dysregulated repair response in mouse lungs. Furthermore, exposure to nicotine‐containing e‐cig aerosols or PG alone differentially affected the release of pro‐inflammatory cytokines in healthy and COPD human 3D EpiAirway tissues. Overall, acute exposure to nicotine‐containing e‐cig aerosols was sufficient to elicit a pro‐inflammatory response and altered mRNA and protein levels of myogenic, lipogenic, and extracellular matrix markers in mouse lung in a sex‐dependent manner. Thus, acute exposure to inhaled nicotine via e‐cig leads to dysregulated repair and inflammatory responses, which may lead to airway remodeling in the lungs.

The effect of e-cigarette aerosol emissions on respiratory health: a narrative review

Introduction: Due to the uptake in the use of e-cigarettes (ECs), evidence on their health effects is needed to inform health care and policy. Some regulators and health professionals have raised concerns that the respirable aerosols generated by ECs contain several constituents of potential toxicological and biological relevance to respiratory health. Areas covered: We critically assess published research on the respiratory system investigating the effects of ECs in preclinical models, clinical studies of people who switched to ECs from tobacco cigarettes, and population surveys. We assess the studies for the quality of their methodology and accuracy of their interpretation. To adequately assess the impact of EC use on human health, addressing common mistakes and developing robust and realistic methodological recommendations is an urgent priority. The findings of this review indicate that ECs under normal conditions of use demonstrate far fewer respiratory risks than combustible tobacco cigarettes. EC users and smokers considering ECs have the right to be informed about the relative risks of EC use, and to be made aware that findings of studies published by the media are not always reliable. Expert opinion: Growing evidence supports the relative safety of EC emission aerosols for the respiratory tract compared to tobacco smoke.

Electronic cigarettes in the indoor environment

The use of electronic cigarettes (e-cigarettes or "vaping") has seen an unprecedented increase worldwide. Vaping has been promoted as a beneficial smoking cessation tool and an alternative nicotine delivery device that contains no combustion by-products. However, nicotine is highly addictive, and the increased use of nicotine-containing e-cigarettes among teens and individuals who are not in need of smoking cessation may lead to overall greater nicotine dependence in the population. Furthermore, available research indicates that vaping solutions and their emissions may contain much more than just nicotine, including aerosolized flavorings, propylene glycol (PG), and other intentional and unintentional contaminants. These materials could present undefined potential health hazards to both e-cigarette users and bystanders, the full extent of which is not well understood at this time. Whereas e-cigarette usage and exposures may lower some or most of the risks associated with conventional cigarette use, the health effects of nicotine and aerosol exposures from e-cigarettes are not well understood. Research indicates that vaping aerosols are not benign, especially for nearby people in areas with limited ventilation and people with compromised health conditions. In addition, e-juice liquids have already been responsible for an increase in accidental poisonings in children. Because the magnitude of health and safety hazards that vaping may present to nonusers remains unclear, it is prudent to manage and control vaping in indoor locations where smoking is currently restricted. Based on a review of current scientific information, the American Industrial Hygiene Association (AIHA) recommends that e-cigarettes should be considered a source of aerosols, volatile organic compounds (VOCs), and particulates in the indoor environment that have not been thoroughly characterized or evaluated for health risk or safety.

Variations in coil temperature/power and e-liquid constituents change size and lung deposition of particles emitted by an electronic cigarette

Electronic cigarette uses propylene glycol and glycerol to deliver nicotine and flavors to the lungs. Given the hundreds of different brands, the thousands of flavors available and the variations in nicotine concentrations, it is likely that electronic cigarette settings and e-liquid composition affect the size distribution of particles emitted and ultimately pulmonary deposition. We used the inExpose e-cigarette extension to study two separate modes of operation of electronic cigarettes, namely power-controlled and the temperature-controlled. We also assessed several e-liquids based on propylene glycol and glycerol concentrations, nicotine content, and selected monomolecular flavoring agents (menthol, vanillin, and maltol). Particle size distribution was measured using a Condensation Particle Counter and a Scanning Mobility Particle Sizer spectrometer. Lung deposition was predicted using the International Commission on Radiological Protection model. For all resistance coils, increase in power delivery generated larger particles while maintaining a higher coil temperature generated smaller particles. Increase in glycerol concentration led to the generation of larger particles. With regard to flavors, we showed that despite minor effect of menthol and maltol, vanillin dramatically increased particle size. Presence of nicotine also increased particle size. Finally, particles emitted by the electronic cigarette were predicted to mainly deposit in the alveoli and conditions generating larger particle sizes led to a reduction in predicted lung deposition. This study shows that coil temperature, propylene glycol and glycerol concentrations, presence of nicotine, and flavors affect the size of particles emitted by an electronic cigarette, directly affecting predicted lung deposition of these particles.

Impact of intervention of biomass cookstove technologies and kitchen characteristics on indoor air quality and human exposure in rural settings of India

This study investigates the impact of increased levels of indoor air pollution (IAP) caused due to biomass burning in the rural households of Northern India. A comparative assessment of the impact of traditional cookstoves (TCS) and improved cookstoves (ICS) coupled with the characteristics of kitchen was conducted to estimate the PM (PM₁₀, PM_2.5, PM₁), CO/CO₂ concentrations in the micro-environments of kitchen and living area of the households. The study incorporated both extensive and intensive real-time indoor air quality (IAQ) monitoring during the two cooking sessions of the day. The pollutant concentrations were reported in terms of 24-h as well as 8-h (cooking hours including morning and evening meal) averages. Influence of the three types of kitchen characteristics, i.e., enclosed, semi-enclosed and open was also comprehensively analyzed to measure its impact on the IAQ. In addition to this, the IAQ was further used to evaluate the particle size distribution (PSD), respiratory tract deposition and exposure index to assess its impact on health status of the exposed group including women involved in cooking practices. The results of the study highlighted that deployment of ICS would help in improving the IAQ of the kitchen area by resulting in reducing the concentrations of PM_10, PM_2.5, PM₁ and CO by 21-62%, 20-80%, 24-87% and 19-93%, respectively. It was also highlighted that the kitchen characteristics significantly influence the accumulation of air pollutants, demonstrated by the results that the IAQ being worst in the case of enclosed kitchen, resulted in the highest exposure index values. Multivariate regression models to predict PM₁ concentration were also developed for three kitchen categories for both TCS and ICS. Thus, the current study concludes that usage of ICS coupled with efficient designing of the kitchen can improve the overall IAQ of the household along with immense health benefits. Overall, the study emphasized the need of more comprehensive studies to fully assess the association of household air pollution (HAP) and health of individual in the rural settings by considering the toxicity of PM.

The Use of Electronic Cigarettes in Pregnancy: A Review of the Literature

Importance

Electronic cigarette (e-cigarette) use in pregnancy has been steadily increasing and has been hyped as being a safe alternative to cigarette smoking during pregnancy. This review discloses what is currently known about e-cigarette use in pregnancy and the effects of its use on pregnancy outcomes.

Objective

To determine what is currently known about the prevalence of e-cigarette use in pregnancy and the effects of e-cigarette use on pregnancy and perinatal/neonatal outcomes.

Evidence Acquisition

A PubMed, CINAHL, and EMBASE search was undertaken using the search terms "pregnancy" OR "pregnancy complications" OR "pregnancy outcome" OR "newborn" OR "neonate" OR "birth" AND "electronic cigarettes" OR "e-cigarettes" OR "ecigarettes" OR "vaping" OR "vape." The search was limited to the English language and between 2007 and October 12, 2017.

Results

The search identified 91 articles, 40 of which are the basis for this review. The prevalence of e-cigarette use is 0.6% to 15%. The amount of nicotine consumed by e-cigarette users is comparable to that consumed by cigarette smokers. Most of the animal model studies suggest a potential danger to the developing fetus primarily because of the nicotine consumed and that consumption has multiple effects on the immune system, neural development, lung function, and cardiac function. There is a widespread flawed perception that e-cigarettes are safe to use during pregnancy.

Conclusions

The marketing of e-cigarette use as a safer alternative to cigarette smoking has led to an increasing use even in pregnancy. The nicotine consumed by e-cigarettes is similar to that consumed by cigarette smoking. Animal studies confirm the dangers of nicotine to the developing fetus. More research needs to be done specifically assessing e-cigarette use, pregnancy, and pregnancy outcomes.

Relevance

The amount of nicotine consumed in cigarette smoking is similar to the amount of nicotine consumed with e-cigarettes. The effects of nicotine exposure during fetal development are well known and include effects on multiple organ systems.

Health risk assessment due to biomass smoke exposure in Indian indoor environment: An empirical approach using lung deposition model

The paper subsumes a framework that assesses health risk due to exposure to different fuel combustion through articulation of modern microscopic techniques, empirical equations, lung diagnostic tools and a pre-existing model that has been extrapolated to futuristic aspects (within controlled conditions). The framework was tested on 132 household cooks belonging to different age groups and using different types of fuel. The inhalable fraction released during fuel combustion varied in morphological characteristics and deposition site. Micrographs obtained using Scanning Electron Microscope (SEM) analysis of (biomass smoke) soot indicates aggregate formation attributing to a higher level of health risk. Further, abnormal ventilatory function along with higher risk (RR > 1) was more evident within biomass fuel users. The condition further exacerbates while using dung cakes due to high levels of emissions (294.3 particles/liter) that deposit in the upper respiratory tract (0.0899). Further, the population attributable risk percent (79%) calculated on the basis of cooking behavior suggests a 'rural culture' health determinant as clean fuel usage is not practiced as an outcome of low literacy and poor income in the region. These preliminary findings highlight the drudgery of impuissant women who are exposed to high particulate emissions on a regular basis which results in reduced lung function. Nevertheless, further cogitation is required to eliminate the limitations in this study and explore further linkages between exposure and vulnerable group to generate meaningful policy recommendations.

The Effects of Electronic Cigarette (ECIG)-Generated Aerosol and Conventional Cigarette Smoke on the Mucociliary Transport Velocity (MTV) Using the Bullfrog (R. catesbiana) Palate Paradigm

Background: While ECIGs are under scrutiny concerning safety, particularly in reference to the physiological impact that aerosolized ECIG liquid (E-liquid) may have on respiratory tissues, others believe that ECIGs are a “Harm Reduction” alternative to conventional cigarettes. Previous studies investigating ciliated respiratory epithelium indicate that smoking shortens cilia length, reduces cilia beat frequency and disrupts respiratory epithelium, which most likely contributes to the inhibition of mucocilliary clearance. Monitoring mucous clearance of respiratory tissues exposed to ECIG-generated aerosol or conventional cigarette smoke, as indexed by mucous transport velocity (MTV), is one way to gauge the impact aerosol and smoke have on the respiratory tract. Therefore, we designed an experiment to test the effect of ECIG-generated aerosol and smoke on MTV using the frog palate paradigm.

Methods: Peristaltic pumps transport ECIG-generated aerosol and conventional cigarette smoke into custom-made chambers containing excised bullfrog palates. MTVs were determined before exposure, immediately after exposure and approximately 1 day following exposure. MTVs were also determined (at the same time points) for palates exposed to air (control). Surface and cross sectional SEM images of palates from all three groups were obtained to support MTV data.

Results: The results indicate that ECIG-generated aerosol has a modest inhibitory effect (p < 0.05) on MTV 1 day post-exposure (0.09 ± 0.01) compared to control MTV (0.16 ± 0.03 mm/s). In contrast, smoke completely inhibits MTV from 0.14 ± 0.03 mm/s immediately before exposure to 0.00 mm/sec immediately after exposure and the MTV is unable to recover 1 day later. SEM images of control palates and palates exposed to ECIG-generated aerosol both show cilia throughout their epithelial surface, while some areas of palates exposed to smoke are completely devoid of cilia. Additionally, the epithelial thickness of aerosol-exposed palates appears thicker than control palates while smoke-exposed palates appear to be thinner due to epithelial disruption.

Conclusions: These results indicate that ECIG-generated aerosol has only a modest effect on mucocilary clearance of bullfrog palates and aerosol sedimentation accounts for epithelial thickening. In accordance with the primary literature, conventional cigarette smoke dramatically inhibits mucociliary clearance and is, in part, due to decreased number of cilia and disruption of the smoke-exposed epithelium.

Electronic Cigarettes: Exposure and Use Among Pediatric Populations

As an emerging inhalational exposure, electronic cigarettes (e-cigarettes) have rapidly gained public awareness with increasing use among adolescents and adults, leading to increased primary use by adolescents and increased secondhand exposure to emissions in infants, children, and adolescents. Although the long-term health risks for primary use and secondhand emission exposure are unknown, limited data from animal studies suggest that there is the potential for long-term lung injury and altered neurocognitive development in children with exposure to nicotine-containing aerosols. In this pediatric-focused review, we discuss the history of e-cigarettes, the demographics of adolescent users, effects on health, and current legislative efforts to protect infants, children, and adolescents from exposure.