Evaluation of electronic cigarette liquids and aerosol for the presence of selected inhalation toxins

Identification of flavouring chemicals and potential toxicants in e-cigarette products in Ontario, Canada

OBJECTIVES

The current study examined constituents of e-cigarette products on the Canadian market, with a focus on the province of Ontario.

METHODS

E-cigarettes were systematically purchased at 80 retail outlets across 4 cities in Ontario, Canada, in January-February 2015. Product constituents were identified using gas chromatography and mass spectrometry. Additionally, tobacco-specific nitrosamines (TSNAs) were quantified in tested products using liquid chromatography with tandem mass spectrometry.

RESULTS

A total of 166 e-cigarette products were purchased, including disposable products (33%), refillable products (14%), and e-liquids (53%). Overall, e-cigarette products had an average of 6.2 (SD = 3.6) flavouring chemicals. E-cigarettes with sweet flavours (e.g., desserts, alcoholic drinks) had a significantly greater number of flavouring chemicals when compared with tobacco- and menthol-flavoured products (p < 0.05). Approximately one fifth (21%) of products contained flavouring chemicals with potential risk of inhalation toxicity (benzyl alcohol, benzaldehyde, vanillin). An additional 8 toxicants (e.g., acrolein, diacetyl) were detected in a total of 14 e-cigarette products. Measurable levels of TSNAs were detected in 70% of tested products.

CONCLUSION

E-cigarettes purchased in Ontario, Canada, contained several constituents that may present excess risk, including some flavouring chemicals and carcinogenic nitrosamines. Further research is needed to determine whether the levels of these constituents have implications for the magnitude of risk to users. The findings reveal several policy gaps that may be addressed by developing regulatory product standards and labelling practices for e-cigarettes.

Endotoxin and [Formula: see text] Contamination in Electronic Cigarette Products Sold in the United States

BACKGROUND

Cigarette smoke contains microbes and microbial toxins, such as endotoxin and [Formula: see text], that may have adverse respiratory effects. To our knowledge, the potential for contamination of electronic cigarette (EC) products sold in the United States has not been investigated.

OBJECTIVES

We aimed to determine whether popular cartridge and e-liquid EC products were contaminated with endotoxin or glucan and to examine differences according to the type and flavor of products.

METHODS

We selected 37 cartridges and 38 e-liquid products with the highest nicotine content from the ten top-selling U.S. brands. Flavors were classified into four groups: tobacco, menthol, fruit, and other. Endotoxin and glucan were measured using an endotoxin-specific kinetic turbidimetric assay and a Glucatell® Kinetic Assay (Associates of Cape Cod, Inc.), respectively.

RESULTS

Endotoxin concentrations were over the limit of detection (LOD) in 17 of 75 products tested (23%), and glucan concentrations were greater than LOD in 61 of 75 products (81%). After adjusting for brand and flavor, the mean glucan concentration was 3.2 times higher [95% confidence interval (CI): [Formula: see text], 18.4] in cartridge vs. e-liquid samples. After adjusting for brand and type of product, glucan concentrations in tobacco- and menthol-flavored ECs were 10.4 (95% CI: 1.8, 44.9) and 3.5 (95% CI: 0.1, 17.3) times higher than concentrations found in fruit-flavored products.

CONCLUSIONS

EC products may be contaminated with microbial toxins. Further studies with large representative samples of products are needed to confirm our findings, identify sources and routes of contamination, and evaluate health effects associated with the use of contaminated products. https://doi.org/10.1289/EHP3469.

Widespread use of flavored e-cigarettes and hookah tobacco in the United States

In 2009, the U.S. Food and Drug Administration banned the sale of flavored cigarettes (excluding menthol) in the U.S. However, the sale of flavored e-cigarettes (FE) and flavored hookah tobacco (FHT) is still legal. In this study (conducted in the US in the period from October 2018 to February 2019), we estimated the prevalence of use of FE and FHT across users' sociodemographic characteristics (e.g., age, sex, race/ethnicity) and identified the key characteristics of tobacco users associated with use of FE and FHT. We analyzed the 2014–2015 Tobacco Use Supplement to the Current Population Survey data for current e-cigarette (n = 3691) and hookah tobacco (n = 658) users. Among e-cigarette users, 65.5% used FE; and among hookah tobacco users, 87.3% used FHT. Among e-cigarette users, the prevalence of use of FE was significantly higher for 18–24 year-old than 45+ year-old adults; women than men; Southern than Northeastern residents; and never smokers of regular cigarettes than current smokers of regular cigarettes (all adjusted p's < 0.05). Among hookah tobacco users, the rates of FHT use were significantly higher for women than men, and never smokers of regular cigarettes than current smokers (all adjusted p's < 0.05). Because availability and accessibility of flavored tobacco products may promote tobacco use, revising regulatory guidelines concerning manufacturing and distribution of FE and FHT may help reduce the popularity of emerging tobacco products.

Implications

Among users of emerging tobacco products such as e-cigarettes and hookah tobacco, use of flavored products is very common. Among e-cigarette users, 66% consumed flavored e-cigarettes; and among users of hookah tobacco, 87% consumed flavored hookah tobacco. Use of flavored products was especially common among users who were young adults, women, or never and former smokers of regular cigarettes. Availability of emerging tobacco products in many different flavors could be a reason for tobacco use initiation and continued use of tobacco after cessation of regular-cigarette smoking.

Use of Flavored E-Cigarettes Among Adolescents, Young Adults, and Older Adults: Findings From the Population Assessment for Tobacco and Health Study

OBJECTIVES

The use of flavored electronic cigarettes (e-cigarettes) is common among e-cigarette users, but little is known about the potential harms of flavorings, the extent to which the concurrent use of multiple flavor types occurs, and the correlates of flavor type use. The objective of this study was to assess the types of e-cigarette flavors used by adolescent (aged 12-17), young adult (aged 18-24), and older adult (aged ≥25) e-cigarette users.

METHODS

We assessed the prevalence of flavored e-cigarette use within the past month by flavor types and concurrent use of multiple flavor types among past-month e-cigarette users sampled during Wave 2 (2014-2015) of the Population Assessment for Tobacco and Health Study among 414 adolescents, 961 young adults, and 1711 older adults. We used weighted logistic regression models for the use of fruit-, candy-, mint/menthol-, tobacco-, or other-flavored e-cigarettes and concurrent use of multiple flavor types. Covariates included demographic characteristics, e-cigarette use frequency, cigarette smoking status, current use of other tobacco products, and reasons for e-cigarette use.

RESULTS

The leading e-cigarette flavor types among adolescents were fruit, candy, and other flavors; among young adults were fruit, candy, and mint/menthol; and among older adults were tobacco or other flavors, fruit, and mint/menthol. Compared with older adults, adolescents and young adults were more likely to use fruit-flavored e-cigarettes (adjusted odds ratio [aOR] = 3.35; 95% confidence interval [CI], 2.56-4.38; and aOR = 2.31; 95% CI, 1.77-3.01, respectively) and candy-flavored e-cigarettes (aOR = 3.81; 95% CI, 2.74-5.28; and aOR = 2.95; 95% CI, 2.29-3.80, respectively) and concurrently use multiple flavor types (aOR = 4.58; 95% CI, 3.39-6.17; and aOR = 2.28; 95% CI, 1.78-2.91, respectively).

CONCLUSIONS

Regulation of sweet e-cigarette flavors (eg, fruit and candy) may help reduce the use of e-cigarettes among young persons without substantially burdening adult e-cigarette users.

Cinnamaldehyde in flavored e-cigarette liquids temporarily suppresses bronchial epithelial cell ciliary motility by dysregulation of mitochondrial function

Aldehydes in cigarette smoke (CS) impair mitochondrial function and reduce ciliary beat frequency (CBF), leading to diminished mucociliary clearance (MCC). However, the effects of aldehyde e-cigarette flavorings on CBF are unknown. The purpose of this study was to investigate whether cinnamaldehyde, a flavoring agent commonly used in e-cigarettes, disrupts mitochondrial function and impairs CBF on well-differentiated human bronchial epithelial (hBE) cells. To this end, hBE cells were exposed to diluted cinnamon-flavored e-liquids and vaped aerosol and assessed for changes in CBF. hBE cells were subsequently exposed to various concentrations of cinnamaldehyde to establish a dose-response relationship for effects on CBF. Changes in mitochondrial oxidative phosphorylation and glycolysis were evaluated by Seahorse Extracellular Flux Analyzer, and adenine nucleotide levels were quantified by HPLC. Both cinnamaldehyde-containing e-liquid and vaped aerosol rapidly yet transiently suppressed CBF, and exposure to cinnamaldehyde alone recapitulated this effect. Cinnamaldehyde impaired mitochondrial respiration and glycolysis in a dose-dependent manner, and intracellular ATP levels were significantly but temporarily reduced following exposure. Addition of nicotine had no effect on the cinnamaldehyde-induced suppression of CBF or mitochondrial function. These data indicate that cinnamaldehyde rapidly disrupts mitochondrial function, inhibits bioenergetic processes, and reduces ATP levels, which correlates with impaired CBF. Because normal ciliary motility and MCC are essential respiratory defenses, inhalation of cinnamaldehyde may increase the risk of respiratory infections in e-cigarette users.

Identification of Cytotoxic Flavor Chemicals in Top-Selling Electronic Cigarette Refill Fluids

We identified the most popular electronic cigarette (EC) refill fluids using an Internet survey and local and online sales information, quantified their flavor chemicals, and evaluated cytotoxicities of the fluids and flavor chemicals. "Berries/Fruits/Citrus" was the most popular EC refill fluid flavor category. Twenty popular EC refill fluids were purchased from local shops, and the ingredient flavor chemicals were identified and quantified by gas chromatography-mass spectrometry. Total flavor chemical concentrations ranged from 0.6 to 27.9 mg/ml, and in 95% of the fluids, total flavor concentration was greater than nicotine concentration. The 20 most popular refill fluids contained 99 quantifiable flavor chemicals; each refill fluid contained 22 to 47 flavor chemicals, most being esters. Some chemicals were found frequently, and several were present in most products. At a 1% concentration, 80% of the refill fluids were cytotoxic in the MTT assay. Six pure standards of the flavor chemicals found at the highest concentrations in the two most cytotoxic refill fluids were effective in the MTT assay, and ethyl maltol, which was in over 50% of the products, was the most cytotoxic. These data show that the cytotoxicity of some popular refill fluids can be attributed to their high concentrations of flavor chemicals.

High concentrations of flavor chemicals are present in electronic cigarette refill fluids

We characterized the flavor chemicals in a broad sample of commercially available electronic cigarette (EC) refill fluids that were purchased in four different countries. Flavor chemicals in 277 refill fluids were identified and quantified by gas chromatography-mass spectrometry, and two commonly used flavor chemicals were tested for cytotoxicity with the MTT assay using human lung fibroblasts and epithelial cells. About 85% of the refill fluids had total flavor concentrations >1 mg/ml, and 37% were >10 mg/ml (1% by weight). Of the 155 flavor chemicals identified in the 277 refill fluids, 50 were present at ≥1 mg/ml in at least one sample and 11 were ≥10 mg/ml in 54 of the refill fluids. Sixty-one% (170 out of 277) of the samples contained nicotine, and of these, 56% had a total flavor chemical/nicotine ratio >2. Four chemicals were present in 50% (menthol, triacetin, and cinnamaldehyde) to 80% (ethyl maltol) of the samples. Some products had concentrations of menthol ("Menthol Arctic") and ethyl maltol ("No. 64") that were 30 times (menthol) and 100 times (ethyl maltol) their cytotoxic concentration. One refill fluid contained cinnamaldehyde at ~34% (343 mg/ml), more than 100,000 times its cytotoxic level. High concentrations of some flavor chemicals in EC refill fluids are potentially harmful to users, and continued absence of any regulations regarding flavor chemicals in EC fluids will likely be detrimental to human health.

High concentrations of flavor chemicals are present in electronic cigarette refill fluids

We characterized the flavor chemicals in a broad sample of commercially available electronic cigarette (EC) refill fluids that were purchased in four different countries. Flavor chemicals in 277 refill fluids were identified and quantified by gas chromatography-mass spectrometry, and two commonly used flavor chemicals were tested for cytotoxicity with the MTT assay using human lung fibroblasts and epithelial cells. About 85% of the refill fluids had total flavor concentrations >1 mg/ml, and 37% were >10 mg/ml (1% by weight). Of the 155 flavor chemicals identified in the 277 refill fluids, 50 were present at ≥1 mg/ml in at least one sample and 11 were ≥10 mg/ml in 54 of the refill fluids. Sixty-one% (170 out of 277) of the samples contained nicotine, and of these, 56% had a total flavor chemical/nicotine ratio >2. Four chemicals were present in 50% (menthol, triacetin, and cinnamaldehyde) to 80% (ethyl maltol) of the samples. Some products had concentrations of menthol ("Menthol Arctic") and ethyl maltol ("No. 64") that were 30 times (menthol) and 100 times (ethyl maltol) their cytotoxic concentration. One refill fluid contained cinnamaldehyde at ~34% (343 mg/ml), more than 100,000 times its cytotoxic level. High concentrations of some flavor chemicals in EC refill fluids are potentially harmful to users, and continued absence of any regulations regarding flavor chemicals in EC fluids will likely be detrimental to human health.

Electronic Cigarettes: Trends, Health Effects and Advising Patients Amid Uncertainty

Dental professionals can be effective tobacco prevention and cessation partners. Electronic cigarettes (e-cigarettes), which deliver aerosolized nicotine but fewer toxicants than found in cigarette smoke, present new and contentious questions for clinicians, patients, and researchers. Evidence suggests e-cigarettes are not harmless but are less dangerous than cigarettes. Smoking cessation effectiveness is unproven and oral and systemic health effects remain under study. Dental professionals must stay informed to provide patients truthful information as new data emerge.

Electronic cigarettes: a task force report from the European Respiratory Society

There is a marked increase in the development and use of electronic nicotine delivery systems or electronic cigarettes (ECIGs). This statement covers electronic cigarettes (ECIGs), defined as "electrical devices that generate an aerosol from a liquid" and thus excludes devices that contain tobacco. Database searches identified published articles that were used to summarise the current knowledge on the epidemiology of ECIG use; their ingredients and accompanied health effects; second-hand exposure; use of ECIGs for smoking cessation; behavioural aspects of ECIGs and social impact; in vitro and animal studies; and user perspectives.ECIG aerosol contains potentially toxic chemicals. As compared to conventional cigarettes, these are fewer and generally in lower concentrations. Second-hand exposures to ECIG chemicals may represent a potential risk, especially to vulnerable populations. There is not enough scientific evidence to support ECIGs as an aid to smoking cessation due to a lack of controlled trials, including those that compare ECIGs with licenced stop-smoking treatments. So far, there are conflicting data that use of ECIGs results in a renormalisation of smoking behaviour or for the gateway hypothesis. Experiments in cell cultures and animal studies show that ECIGs can have multiple negative effects. The long-term effects of ECIG use are unknown, and there is therefore no evidence that ECIGs are safer than tobacco in the long term. Based on current knowledge, negative health effects cannot be ruled out.

[New tobacco products, a threat for tobacco control and public health of Mexico]

The new tobacco products that include electronic cigarettes (called "E Cig", "e-hookahs", "mods", "vape-pens"), electronic nicotine delivery systems (SEAN, Spanish acronym), similar systems without nicotine (SSSN, Spanish acronym) and alternative nicotine consumption systems (SACN, Spanish acronym), are positioned in the global market with a discourse of harm reduction and risk minimization. This manuscript summarizes the scientific evidence and presents a regulatory proposal for this technological innovation, oriented to guide the decision making of legislators, government institutions and organized civil society. The scientific evidence concludes that there is no safe tobacco product for health. The addictive nature of nicotine and the health damages for children, adolescents and pregnant women is the fundamental argument. These new products promote the transition to conventional cigarettes and have not shown efficacy for smoking cessation, on the contrary, they promote dual use. High-level regulation must be formulated without the intervention of the manufacturers or institutions with a conflict of interest in the context of the complete and integral World Health Organization Framework Convention on Tobacco Control implementation.

Vaping associated with healthy food words: A content analysis of Twitter

E-cigarettes were initially introduced as a less harmful alternative to combustible cigarettes, but marketing efforts may now be exceeding these claims by associating e-cigarettes with words related to healthy foods. These associations could mislead people to assume vaping is a healthy practice. Tweets from January to March 2017 were obtained from the Twitter Streaming Application Programming Interface (API) to assess content about vaping linked to healthy food words. Tweets were classified into one of nine categories along with their source (marketer vs. non-marketer). We content analyzed original English language public postings on Twitter that included vaping-related keywords and at least one of eight co-occurring healthy food-related labels (e.g., 'natural,' 'vitamin,' 'vegan,' and 'organic') (N = 1205). Chi-square analyses compared themes by message source. Findings suggest vaping is being marketed in ways that could paradoxically lead consumers to believe that e-cigarettes are health-enhancing. We found more tweets representing vaping as health-enhancing (9%) than referring to it as a smoking-cessation device (1%). The largest category of tweets referred to vaping as harmless (28%) and therefore compatible with a healthy lifestyle. Tweets presenting vaping as harmless or with a sensation theme were more likely to be authored by marketers than by non-marketers. Food and drug regulation needs to be more vigilant to prevent misleading advertising from e-cigarette marketers.

The characterization of flavored hookahs aroma profile and in response to heating as analyzed via headspace solid-phase microextraction (SPME) and chemometrics

Flavors profiling in flavored hookah tobacco is an issue of increasing scrutiny for the health sector owing to its adverse effects on humans, especially being heated to produce smoke. This study aims at tackling the components involved in the flavored hookah tobacco from a chemical and biological point of view. Detecting individual flavor compounds, within a complex hookah tobacco matrix was accomplished using headspace solid phase microextraction (SPME). A total of 114 volatiles were identified in 13 flavored hookah tobacco products, with esters amounting for the major component up to 40%. Whereas oxygenated monoterpenes presented another major volatile class, contributing up to 23%, including (E)-anethole. Superheating flavored hookah tobacco at 190 °C resulted in the release of a mixture of phenol derivatives and polycyclic aromatic compounds that are indicative of coal tar, a major component produced during hookah tobacco usage with potential health hazards. This study provides the first comprehensive volatile profile of hookah tobacco products from different origins identifying chemical components involved in flavors. It is expected to serve as informative grounds for the better understanding of hookah tobacco production and usage. The information presented is also expected to raise awareness on the health risks of hookah tobacco smoking.

Patterns of awareness and use of electronic cigarettes in Mexico, a middle-income country that bans them: Results from a 2016 national survey

Among high-income countries, awareness and use of e-cigarettes is lower in countries with more restrictive e-cigarette regulations. Little is known about e-cigarettes in middle-income countries, many of which like Mexico, ban e-cigarette sales and marketing. The current study determined the national-level prevalence and correlates of e-cigarette awareness and consumption in Mexico. Data were analyzed from a 2016 nationally representative survey. Prevalence of e-cigarette awareness, trial and current use was estimated separately for adolescents (n = 12,436), adult nonsmokers (n = 36,966), and adult smokers (n = 7347). For each group, crude and adjusted logistic models regressed e-cigarette outcomes on sociodemographic and smoking-related variables, adjusting for the sampling design and weights. Prevalence varied across subgroups for e-cigarette awareness (adolescents = 45.3%; adult nonsmokers = 33.9%; adult smokers = 54.3%), e-cigarette trial (adolescents = 6.5%; adult nonsmokers = 2.6%; adult smokers = 18.2%) and current use of electronic cigarettes (adolescents = 1.1%; adult nonsmokers = 0.3%; adult smokers = 4.5%). Among adolescents and adults, current smoking and higher smoking frequency were significantly associated with e-cigarette awareness, trial and use. Among adolescents and nonsmokers, awareness, trial and use of e-cigarette were significantly lower among females than males. Among adult smokers, however, females were more likely to use e-cigarettes than males (AOR = 1.80; 95% CI = 1.08-3.02). Higher education and greater wealth increased the likelihood of trial of e-cigarettes among adult nonsmokers and smokers. Despite the ban on the distribution and sales of e-cigarettes, a substantial number of Mexicans, have access to e-cigarettes. Decision makers and advocates should consider e-cigarette regulations as recommended by the WHO, at the same time Mexico must invest in the infrastructure needed to enforce these regulations.

E-cigarettes-An unintended illicit drug delivery system

Since the introduction of electronic cigarettes (e-cigarettes) in 2003, the technology has advanced allowing for greater user modifications, with users now able to control voltage, battery power, and constituents of the e-cigarette liquid. E-cigarettes have been the subject of a growing body of research with most research justifiably focused on the chemical makeup and risk analysis of chemicals, metals, and particulates found in e-cigarette liquids and vapor. Little research to date has focused on assessing the risks associated with the drug delivery unit itself and its potential for use as an illicit drug delivery system. In light of this, a range of illicit drugs was researched focusing on pharmacodynamics, usual method of administration, the dosage required for toxicity, toxic effects, and evidence of existing use in e-cigarettes in both literature and online illicit drug forums. A systematic literature search found evidence of current use of e-cigarettes to vape almost all illicit drug types analyzed. This presents both a potential population health risk and a management issue for clinicians. It also raises the issue of policing illicit drugs due to potential altered characteristic smells and storage within e-cigarette fluids. E-cigarettes are a viable illicit drug delivery system with evidence both inside and outside of the formal medical literature detailing their potential use for drug delivery of a wide range of illicit and legal drugs.

Accounting for effects of system dynamics to improve accuracy of emissions reported in e-cig vaping machines

Laboratory emissions testing of electronic cigarettes continues to be a focus in the tobacco research community. In particular, to inform policy regarding appropriate test protocols to regulate the manufacture, marketing and sale of tobacco products. This study aims to enhance current understanding of the way laboratory systems used to generate topography profiles and capture resultant emissions from inhaled tobacco products may interact with the device under test. A programmable emission system (vaping machine) is introduced and characterized. The operating envelope of this system is presented. This study demonstrates that the performance of an emissions system may be influenced by various factors, resulting in discrepancies between command puff parameter inputs and the observed puffs generated. The study findings conclude that any emissions system should be characterized with the desired test device to determine the effective operating range of the system under "Load" conditions. Furthermore, reporting emissions from electronic cigarettes as a function of "command" puff flow rate and cumulative volume result in under-estimation bias and may give rise to incorrect conclusions regarding the impact of product characteristics on emissions. Conversely, reporting emissions in terms of "observed" puff flow rate and cumulative volume reduces bias errors and limits opportunity for intentional misrepresentation of results.

Environmental Electronic Vape Exposure from Four Different Generations of Electronic Cigarettes: Airborne Particulate Matter Levels

Electronic cigarettes (e-cigs) were introduced into the market in 2006 and their technological features have evolved substantially over time. Currently, there are four different generations of e-cigs that are broadly considered less harmful than the use of combusted tobacco products although passive exposure to aerosols often occurs in public spaces and indoor environments. The study aim was to evaluate the levels of airborne particulate matter (PM) emitted during the use of all the four generations of e-cigs, testing different use modalities. PM₁₀, PM₄, PM_2.5 and PM₁ were measured through a Dusttrak ™ II Aerosol Monitor, for a total of 20 independent experiments. All tested e-cigs devices produced PM during their use, and PM₁₀ was almost made of PM₁ size fraction. In addition, we observed a progressive increase in PM emission from the first to the fourth generation, and an upward trend of PM₁ emitted by the fourth generation e-cig with an increase in the operating power. The results showed that, whatever the model adopted, passive vaping does occur. This finding supports the need for legislative interventions to regulate the e-cigs use in public places and other enclosed environments, in order to protect the health of any subject who is potentially exposed.

Headspace analysis for screening of volatile organic compound profiles of electronic juice bulk material

The use of electronic nicotine delivery systems continues to gain popularity, and there is concern for potential health risks from inhalation of aerosol and vapor produced by these devices. An analytical method was developed that provided quantitative and qualitative chemical information for characterizing the volatile constituents of bulk electronic cigarette liquids (e-liquids) using a static headspace technique. Volatile organic compounds (VOCs) were screened from a convenience sample of 146 e-liquids by equilibrating 1 g of each e-liquid in amber vials for 24 h at room temperature. Headspace was transferred to an evacuated canister and quantitatively analyzed for 20 VOCs as well as tentatively identified compounds using a preconcentrator/gas chromatography/mass spectrometer system. The e-liquids were classified into flavor categories including brown, fruit, hybrid dairy, menthol, mint, none, tobacco, and other. 2,3-Butanedione was found at the highest concentration in brown flavor types, but was also found in fruit, hybrid dairy, and menthol flavor types. Benzene was observed at concentrations that are concerning given the carcinogenicity of this compound (max 1.6 ppm in a fruit flavor type). The proposed headspace analysis technique coupled with partition coefficients allows for a rapid and sensitive prediction of the volatile content in the liquid. The technique does not require onerous sample preparation, dilution with organic solvents, or sampling at elevated temperatures. Static headspace screening of e-liquids allows for the identification of volatile chemical constituents which is critical for identifying and controlling emission of potentially hazardous constituents in the workplace.

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.

Sugar and Aldehyde Content in Flavored Electronic Cigarette Liquids

Introduction

Sugars are major constituents and additives in traditional tobacco products, but little is known about their content or related toxins (formaldehyde, acetaldehyde, and acrolein) in electronic cigarette (e-cigarette) liquids. This study quantified levels of sugars and aldehydes in e-cigarette liquids across brands, flavors, and nicotine concentrations (n = 66).

Methods

Unheated e-cigarette liquids were analyzed using liquid chromatography mass spectrometry and enzymatic test kits. Generalized linear models, Fisher's exact test, and Pearson's correlation coefficient assessed sugar, aldehyde, and nicotine concentration associations.

Results

Glucose, fructose and sucrose levels exceeded the limits of quantification in 22%, 53% and 53% of the samples. Sucrose levels were significantly higher than glucose [χ2(1) = 85.9, p < .0001] and fructose [χ2(1) = 10.6, p = .001] levels. Formaldehyde, acetaldehyde, and acrolein levels exceeded the limits of quantification in 72%, 84%, and 75% of the samples. Acetaldehyde levels were significantly higher than formaldehyde [χ2(1) = 11.7, p = .0006] and acrolein [χ2(1) = 119.5, p < .0001] levels. Differences between nicotine-based and zero-nicotine labeled e-cigarette liquids were not statistically significant for sugars or aldehydes. We found significant correlations between formaldehyde and fructose (-0.22, p = .004) and sucrose (-0.25, p = .002) and acrolein and fructose (-0.26, p = .0006) and sucrose (-0.21, p = .0006). There were no significant correlations between acetaldehyde and any of the sugars or any of the aldehydes and glucose.

Conclusions

Sugars and related aldehydes were identified in unheated e-cigarette liquids and their composition may influence experimentation in naïve users and their potential toxicity.

Implications

The data can inform the regulation of specific flavor constituents in tobacco products as a strategy to protect young people from using e-cigarettes, while balancing FDA's interest in how these emerging products could potentially benefit adult smokers who are seeking to safely quit cigarette smoking. The data can also be used to educate consumers about ingredients in products that may contain nicotine and inform future FDA regulatory policies related to product standards and accurate and comprehensible labeling of e-cigarette liquids.

"Okay, We Get It. You Vape": An Analysis of Geocoded Content, Context, and Sentiment regarding E-Cigarettes on Twitter

The current study examined conversations on Twitter related to use and perceptions of e-cigarettes in the United States. We employed the Social Media Analytic and Research Testbed (SMART) dashboard, which was used to identify and download (via a public API) e-cigarette-related geocoded tweets. E-cigarette-related tweets were collected continuously using customized geo-targeted Twitter APIs. A total of 193,051 tweets were collected between October 2015 and February 2016. Of these tweets, a random sample of 973 geocoded tweets were selected and manually coded for information regarding source, context, and message characteristics. Our findings reveal that although over half of tweets were positive, a sizeable portion was negative or neutral. We also found that, among those tweets mentioning a stigma of e-cigarettes, most confirmed that a stigma does exist. Conversely, among tweets mentioning the harmfulness of e-cigarettes, most denied that e-cigarettes were a health hazard. These results suggest that current efforts have left the public with ambiguity regarding the potential dangers of e-cigarettes. Consequently, it is critical to communicate the public health stance on this issue to inform the public and provide counterarguments to the positive sentiments presently dominating conversations about e-cigarettes on social media. The lack of awareness and need to voice a public health position on e-cigarettes represents a vital opportunity to continue winning gains for tobacco control and prevention efforts through health communication interventions targeting e-cigarettes.

Analytical and toxicological evaluation of flavor chemicals in electronic cigarette refill fluids

Thousands of electronic cigarette refill fluids are commercially available. The concentrations of nicotine and the solvents, but not the flavor chemicals, are often disclosed on product labels. The purpose of this study was to identify and quantify flavor chemicals in 39 commercial refill fluids that were previously evaluated for toxicity. Twelve flavor chemicals were identified with concentrations ≥1 mg/ml: cinnamaldehyde, menthol, benzyl alcohol, vanillin, eugenol, p-anisaldehyde, ethyl cinnamate, maltol, ethyl maltol, triacetin, benzaldehyde, and menthone. Transfer of these flavor chemicals into aerosols made at 3V and 5V was efficient (mean transfer = 98%). We produced lab-made refill fluids containing authentic standards of each flavor chemical and analyzed the toxicity of their aerosols produced at 3V and 5V using a tank Box Mod device. Over 50% of the refill fluids in our sample contained high concentrations of flavor chemicals that transferred efficiently to aerosols at concentrations that produce cytotoxicity. When tested with two types of human lung cells, the aerosols made at 5V were generally more toxic than those made at 3V. These data will be valuable for consumers, physicians, public health officials, and regulatory agencies when discussing potential health concerns relating to flavor chemicals in electronic cigarette products.

Analytical and toxicological evaluation of flavor chemicals in electronic cigarette refill fluids

Thousands of electronic cigarette refill fluids are commercially available. The concentrations of nicotine and the solvents, but not the flavor chemicals, are often disclosed on product labels. The purpose of this study was to identify and quantify flavor chemicals in 39 commercial refill fluids that were previously evaluated for toxicity. Twelve flavor chemicals were identified with concentrations ≥1 mg/ml: cinnamaldehyde, menthol, benzyl alcohol, vanillin, eugenol, p-anisaldehyde, ethyl cinnamate, maltol, ethyl maltol, triacetin, benzaldehyde, and menthone. Transfer of these flavor chemicals into aerosols made at 3V and 5V was efficient (mean transfer = 98%). We produced lab-made refill fluids containing authentic standards of each flavor chemical and analyzed the toxicity of their aerosols produced at 3V and 5V using a tank Box Mod device. Over 50% of the refill fluids in our sample contained high concentrations of flavor chemicals that transferred efficiently to aerosols at concentrations that produce cytotoxicity. When tested with two types of human lung cells, the aerosols made at 5V were generally more toxic than those made at 3V. These data will be valuable for consumers, physicians, public health officials, and regulatory agencies when discussing potential health concerns relating to flavor chemicals in electronic cigarette products.

Mechanisms of toxicity and biomarkers of flavoring and flavor enhancing chemicals in emerging tobacco and non-tobacco products

Tobacco products containing flavorings, such as electronic nicotine delivery devices (ENDS) or e-cigarettes, cigars/cigarillos, waterpipes, and heat-not-burn devices (iQOS) are continuously evolving. In addition to increasing the exposure of teenagers and adults to nicotine containing flavoring products and flavoring enhancers, chances of nicotine addiction through chronic use and abuse also increase. These flavorings are believed to be safe for ingestion, but little information is available about their effects on the lungs. In this review, we have discussed the in vitro and in vivo data on toxicity of flavoring chemicals in lung cells. We have further discussed the common flavoring agents, such as diacetyl and menthol, currently available detection methods, and the toxicological mechanisms associated with oxidative stress, inflammation, mucociliary clearance, and DNA damage in cells, mice, and humans. Finally, we present potential biomarkers that could be utilized for future risk assessment. This review provides crucial parameters important for evaluation of risk associated with flavoring agents and flavoring enhancers used in tobacco products and ENDS. Future studies can be designed to address the potential toxicity of inhaled flavorings and their biomarkers in users as well as in chronic exposure studies.

Comparing the cytotoxicity of electronic cigarette fluids, aerosols and solvents

BACKGROUND

As thousands of electronic cigarette (e-cigarette) refill fluids continue to be formulated and distributed, there is a growing need to understand the cytotoxicity of the flavouring chemicals and solvents used in these products to ensure they are safe. The purpose of this study was to compare the cytotoxicity of e-cigarette refill fluids/solvents and their corresponding aerosols using in vitro cultured cells.

METHODS

E-cigarette refill fluids and do-it-yourself products were screened in liquid and aerosol form for cytotoxicity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The sensitivity of human pulmonary fibroblasts, lung epithelial cells (A549) and human embryonic stem cells to liquids and aerosols was compared. Aerosols were produced using Johnson Creek's Vea cartomizer style e-cigarette.

RESULTS

A hierarchy of potency was established for the aerosolised products. Our data show that (1) e-cigarette aerosols can produce cytotoxic effects in cultured cells, (2) four patterns of cytotoxicity were found when comparing refill fluids and their corresponding aerosols, (3) fluids accurately predicted aerosol cytotoxicity 74% of the time, (4) stem cells were often more sensitive to aerosols than differentiated cells and (5) 91% of the aerosols made from refill fluids containing only glycerin were cytotoxic, even when produced at a low voltage.

CONCLUSIONS

Our data show that various flavours/brands of e-cigarette refill fluids and their aerosols are cytotoxic and demonstrate the need for further evaluation of e-cigarette products to better understand their potential health effects.

Helping Patients With ESRD and Earlier Stages of CKD to Quit Smoking

Among the many adverse effects of tobacco exposure is the increased risk for progression of kidney disease. Individuals with chronic kidney disease (CKD), who already face increased cardiovascular event rates compared to the general population, are at even greater risk if they smoke. Despite these risks and the increased focus on smoking cessation in the general population in recent years, national guidelines have not specifically targeted individuals with CKD. There are similarly sparse data specific to individuals with CKD regarding the safety and efficacy of evidence-based smoking cessation modalities. This review aims to identify the risks of nicotine dependence in individuals with CKD and the potential benefits of smoking cessation; discuss current strategies for smoking cessation, including behavioral and pharmacologic therapies such as varenicline; and extrapolate these interventions to the unique challenges of this population. Much of the data presented stem from evidence for the general population but are described with additional consideration in dosing of nicotine replacement therapy, as well as non-nicotine pharmacotherapy and treatment modality for individuals with CKD.

Measuring perceptions related to e-cigarettes: Important principles and next steps to enhance study validity

Measuring perceptions associated with e-cigarette use can provide valuable information to help explain why youth and adults initiate and continue to use e-cigarettes. However, given the complexity of e-cigarette devices and their continuing evolution, measures of perceptions of this product have varied greatly. Our goal, as members of the working group on e-cigarette measurement within the Tobacco Centers of Regulatory Science (TCORS) network, is to provide guidance to researchers developing surveys concerning e-cigarette perceptions. We surveyed the 14 TCORS sites and received and reviewed 371 e-cigarette perception items from seven sites. We categorized the items based on types of perceptions asked, and identified measurement approaches that could enhance data validity and approaches that researchers may consider avoiding. The committee provides suggestions in four areas: (1) perceptions of benefits, (2) harm perceptions, (3) addiction perceptions, and (4) perceptions of social norms. Across these 4 areas, the most appropriate way to assess e-cigarette perceptions depends largely on study aims. The type and number of items used to examine e-cigarette perceptions will also vary depending on respondents' e-cigarette experience (i.e., user vs. non-user), level of experience (e.g., experimental vs. established), type of e-cigarette device (e.g., cig-a-like, mod), and age. Continuous formative work is critical to adequately capture perceptions in response to the rapidly changing e-cigarette landscape. Most important, it is imperative to consider the unique perceptual aspects of e-cigarettes, building on the conventional cigarette literature as appropriate, but not relying on existing conventional cigarette perception items without adjustment.

Influence of Flavors on the Propagation of E-Cigarette-Related Information: Social Media Study

Background

Modeling the influence of e-cigarette flavors on information propagation could provide quantitative policy decision support concerning smoking initiation and contagion, as well as e-cigarette regulations.

Objective

The objective of this study was to characterize the influence of flavors on e-cigarette–related information propagation on social media.

Methods

We collected a comprehensive dataset of e-cigarette–related discussions from public Pages on Facebook. We identified 11 categories of flavors based on commonly used categorizations. Each post’s frequency of being shared served as a proxy measure of information propagation. We evaluated a set of regression models and chose the hurdle negative binomial model to characterize the influence of different flavors and nonflavor control variables on e-cigarette–related information propagation.

Results

We found that 5 flavors (sweet, dessert & bakery, fruits, herbs & spices, and tobacco) had significantly negative influences on e-cigarette–related information propagation, indicating the users’ tendency not to share posts related to these flavors. We did not find a positive significance of any flavors, which is contradictory to previous research. In addition, we found that a set of nonflavor–related factors were associated with information propagation.

Conclusions

Mentions of flavors in posts did not enhance the popularity of e-cigarette–related information. Certain flavors could even have reduced the popularity of information, indicating users’ lack of interest in flavors. Promoting e-cigarette–related information with mention of flavors is not an effective marketing approach. This study implies the potential concern of users about flavorings and suggests a need to regulate the use of flavorings in e-cigarettes.

An evaluation of electronic cigarette formulations and aerosols for harmful and potentially harmful constituents (HPHCs) typically derived from combustion

U.S. FDA draft guidance recommends reporting quantities of designated harmful and potentially harmful constituents (HPHCs) in e-cigarette e-liquids and aerosols. The HPHC list comprises potential matrix-related compounds, flavors, nicotine, tobacco-related impurities, leachables, thermal degradation products, and combustion-related compounds. E-cigarettes contain trace levels of many of these constituents due to tobacco-derived nicotine and thermal degradation. However, combustion-related HPHCs are not likely to be found due to the relatively low operating temperatures of most e-cigarettes. The purpose of this work was to use highly sensitive, selective, and validated analytical methods to determine if these combustion-related HPHCs (three aromatic amines, five volatile organic compounds, and the polycyclic aromatic hydrocarbon benzo[a]pyrene) are detectable in commercial refill e-liquids, reference e-cigarette e-liquids, and aerosols generated from rechargeable e-cigarettes with disposable cartridges (often referred to as "cig-a-likes"). In addition, the transfer efficiency of these constituents from e-liquid to aerosol was evaluated when these HPHCs were added to the e-liquids prior to aerosol formation. This work demonstrates that combustion-related HPHCs are not present at measurable levels in the commercial and reference e-liquids or e-cigarette aerosols tested. Additionally, when combustion-related HPHCs are added to the e-liquids, they transfer to the aerosol with transfer efficiencies ranging from 49% to 99%.

Evaluation of flavour profiles in e-cigarette refill solutions using gas chromatography-tandem mass spectrometry

Many flavour compounds that are present in e-liquids for e-cigarettes are responsible for specific tastes and smoking sensations for users. Data concerning content and specific types of flavours is often limited and unknown to users. The aim of the research was to define and compare flavour profiles of e-liquids with the same group taste from different manufacturers. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was used to separate and identify 90 popular compounds (98, including isomers) of interest. The developed method was validated in terms of accuracy (88-113%) for three spiking levels and the intra-day (0.2-13%) and inter-day precision (1-10%). Limits of quantitation were in the range of 10-816 ng/mL, while the matrix effects for 80% of the compounds were at negligible levels. The proposed method is rapid, simple and reliable and uses a green and modern GC-MS/MS technique. Twenty-five samples of five different flavours (tobacco, strawberry, cherry, menthol and apple) from five different producers were analysed, and the determined compounds were categorized and differentiated. The approach proposed in this study allowed for the evaluation of which compounds/group of compounds are responsible for taste and to distinguish common flavour compounds among the investigated brands for each flavour. Furthermore, the presented research can be considered in future toxicological studies.

Microglia Activation and Gene Expression Alteration of Neurotrophins in the Hippocampus Following Early-Life Exposure to E-Cigarette Aerosols in a Murine Model

Recent epidemiological data indicate that the popularity of electronic cigarettes (e-cigarettes), and consequently nicotine use, is rising in both adolescent and adult populations. As nicotine is a known developmental neurotoxin, these products present a potential threat for those exposed during early life stages. Despite this, few studies have evaluated the toxicity of e-cigarettes on the developing central nervous system. The goal of this study was to assess neurotoxicity resulting from early-life exposure to electronic cigarette aerosols in an in vivo model. Specifically, studies here focused on neuro-parameters related to neuroinflammation and neurotrophins. To accomplish this, pregnant and neonatal C57BL/6 mice were exposed to aerosols produced from classic tobacco flavor e-cigarette cartridges (with [13 mg/ml] and without nicotine) during gestation (∼3 weeks) and lactation (∼3 weeks) via whole-body inhalation. Exposure to e-cigarette aerosols with and without nicotine caused significant reductions in hippocampal gene expression of Ngfr and Bdnf, as well as in serum levels of cytokines IL-1β, IL-2, and IL-6. Exposure to e-cigarette aerosols without nicotine enhanced expression of Iba-1, a specific marker of microglia, in the cornus ammonis 1 region of the hippocampus. Overall, our novel results indicate that exposure to e-cigarette aerosols, with and without nicotine, poses a considerable risk to the developing central nervous system. Consequently, e-cigarettes should be considered a potential public health threat, especially early in life, requiring further research and policy considerations.

Qualitative Analysis of E-Liquid Emissions as a Function of Flavor Additives Using Two Aerosol Capture Methods

This work investigates emissions sampling methods employed for qualitative identification of compounds in e-liquids and their resultant aerosols to assess what capture methods may be sufficient to identify harmful and potentially harmful constituents present. Three popular e-liquid flavors (cinnamon, mango, vanilla) were analyzed using qualitative gas chromatography-mass spectrometry (GC-MS) in the un-puffed state. Each liquid was also machine-puffed under realistic-use flow rate conditions and emissions were captured using two techniques: filter pads and methanol impingers. GC-MS analysis was conducted on the emissions captured using both techniques from all three e-liquids. The e-liquid GC-MS analysis resulted in positive identification of 13 compounds from the cinnamon flavor e-liquid, 31 from mango, and 19 from vanilla, including a number of compounds observed in all e-liquid experiments. Nineteen compounds were observed in emissions which were not present in the un-puffed e-liquid. Qualitative GC-MS analysis of the emissions samples identify compounds observed in all three samples: e-liquid, impinge, and filter pads, and each subset thereof. A limited number of compounds were observed in emissions captured with impingers, but were not observed in emissions captured using filter pads; a larger number of compounds were observed on emissions collected from the filter pads, but not those captured with impingers. It is demonstrated that sampling methods have different sampling efficiencies and some compounds might be missed using only one method. It is recommended to investigate filter pads, impingers, thermal desorption tubes, and solvent extraction resins to establish robust sampling methods for emissions testing of e-cigarette emissions.

Are Cigarette Smokers', E-Cigarette Users', and Dual Users' Health-Risk Beliefs and Responses to Advertising Influenced by Addiction Warnings and Product Type?

Introduction

This research examines cigarette smokers' and e-cigarette users' product-related health-risk beliefs across tobacco products and considers the effects of addiction warnings on consumers' responses to persuasion attempts.

Aims and Methods

Study 1 used a cross-sectional survey with a sample of 195 adult cigarette smokers, e-cigarette users, and dual users to examine health-risk beliefs associated with combustible cigarettes and e-cigarettes (cancer, lung disease, stroke, heart disease, harm to an unborn baby, and addiction). Using a sample of 265 adult cigarette smokers, e-cigarette users, and dual users, Study 2 used a between-subjects experiment to examine the effects of an addiction warning presented in an advertisement on health-risk beliefs and willingness to try the promoted product.

Results

Study 1 results reveal that health-risk beliefs for cigarettes are extremely high, whereas health-risk beliefs for e-cigarettes are lower and vary across specific health-risk beliefs; specifically, beliefs related to addiction and harm to an unborn baby are greater than other risk beliefs. Extending these findings, Study 2 results demonstrate that health-risk beliefs associated with cigarette smoking are not affected by an addiction warning in a cigarette advertisement. However, an addiction warning in an e-cigarette advertisement does modify e-cigarette-related risk beliefs, which, in turn, reduces consumers' willingness to try the promoted e-cigarette.

Conclusions

Findings indicate that the addition of an addiction warning may be effective in changing consumers' risk beliefs associated with e-cigarettes and consumers' responses to e-cigarette persuasion attempts.

Implications

By examining cigarette smokers' and e-cigarette users' product-related health-risk beliefs and considering the effects of an addiction warning on consumers' responses to persuasion attempts, this research contributes to the understanding of how warnings in tobacco promotion affect cigarette smokers', e-cigarette users', and dual users' health-risk beliefs and willingness to try promoted products. Specifically, findings show that health-risk beliefs associated with e-cigarettes can be modified using an addiction warning in an e-cigarette advertisement, whereas health-risk beliefs associated with combustible cigarettes are not influenced by an addiction warning.

E-cigarettes: Impact of E-Liquid Components and Device Characteristics on Nicotine Exposure

BACKGROUND

Electronic cigarette (e-cigarette) use has increased substantially in recent years. While e-cigarettes have been proposed as a potentially effective smoking cessation tool, dualuse in smokers is common and e-cigarettes are widely used by non-smokers, including youth and young-adult non-smokers. Nicotine, the primary addictive component in cigarettes, is present at varying levels in many e-liquids. E-cigarettes may lead to initiation of nicotine use in adult and youth non-smokers, re-initiation of nicotine dependence in ex-smokers or increased severity of nicotine dependence in dual-users of cigarettes and e-cigarettes. As such, there are important clinical and policy implications to understanding factors impacting nicotine exposure from e-cigarettes. However, the broad and rapidly changing range of e-liquid constituents and e-cigarette hardware which could impact nicotine exposure presents a challenge. Recent changes in regulatory oversight of e-cigarettes underscore the importance of synthesizing current knowledge on common factors which may impact nicotine exposure.

METHODS

This review focuses on factors which may impact nicotine exposure by changing e-cigarette use behavior, puff topography, altering the nicotine yield (amount of nicotine exiting the e-cigarette mouth piece including nicotine exhaled as vapor) or more directly by altering nicotine absorption and bioavailability.

RESULTS

Topics reviewed include e-liquid components or characteristics including flavor additives (e.g., menthol), base e-liquid ingredients (propylene glycol, vegetable glycerin), components commonly used to dissolve flavorants (e.g., ethanol), and resulting properties of the e-liquid (e.g., pH), e-cigarette device characteristics (e.g., wattage, temperature, model) and user behavior (e.g., puff topography) which may impact nicotine exposure.

CONCLUSION

E-liquid characteristics and components, e-cigarette hardware and settings, and user behavior can all contribute substantially to nicotine exposure from e-cigarettes.

Electronic cigarette-generated aldehydes: The contribution of e-liquid components to their formation and the use of urinary aldehyde metabolites as biomarkers of exposure

Electronic cigarettes (e-cigarette) have emerged as a popular electronic nicotine delivery system (ENDS) in the last decade. Despite the absence of combustion products and toxins such as carbon monoxide (CO) and tobacco-specific nitrosamines (TSNA), carbonyls including short-chain, toxic aldehydes have been detected in e-cigarette-derived aerosols up to levels found in tobacco smoke. Given the health concerns regarding exposures to toxic aldehydes, understanding both aldehyde generation in e-cigarette and e-cigarette exposure is critical. Thus, we measured aldehydes generated in aerosols derived from propylene glycol (PG):vegetable glycerin (VG) mixtures and from commercial e-liquids with flavorants using a state-of-the-art carbonyl trap and mass spectrometry. To track e-cigarette exposure in mice, we measured urinary metabolites of 4 aldehydes using ULPC-MS/MS or GC-MS. Aldehyde levels, regardless of abundance (saturated: formaldehyde, acetaldehyde >> unsaturated: acrolein, crotonaldehyde), were dependent on the PG:VG ratio and the presence of flavorants. The metabolites of 3 aldehydes - formate, acetate and 3-hydroxypropyl mercapturic acid (3-HPMA; acrolein metabolite) -- were increased in urine after e-cigarette aerosol and mainstream cigarette smoke (MCS) exposures, but the crotonaldehyde metabolite (3-hydroxy-1-methylpropylmercapturic acid, HPMMA) was increased only after MCS exposure. Interestingly, exposure to menthol-flavored e-cigarette aerosol increased the levels of urinary 3-HPMA and sum of nicotine exposure (nicotine, cotinine, trans-3'-hydroxycotinine) relative to exposure to a Classic Tobacco-flavored e-cigarette aerosol. Comparing these findings with aerosols of other ENDS and by measuring aldehyde-derived metabolites in human urine following exposure to e-cigarette aerosols will further our understanding of the relationship between ENDS use, aldehyde exposure and health risk.

Electronic cigarettes: an aid in smoking cessation, or a new health hazard?

The issue of electronic cigarettes is one of the most controversial topics in public health. There is intense debate and dividing opinions about their use patterns, health effects and association with smoking. This is expected since they were only recently introduced to the market and they refer to a harm-reduction approach and strategy that is not universally accepted for smoking and tobacco use in the public health community. Three main factors determine the public health impact of electronic cigarettes: (1) their safety/risk profile, both relative to smoking and in absolute terms; (2) their effectiveness for smoking reduction and cessation; (3) the patterns of use by different population subgroups, especially never-smokers, and adoption of use by youth. This analysis presents a brief overview of currently available evidence and gaps in research covering these three factors.

Early age of e-cigarette use onset mediates the association between impulsivity and e-cigarette use frequency in youth

BACKGROUND

Identifying risk factors for youth e-cigarette use is critical, given high rates of e-cigarette use and unknown health effects of long-term use. The current study examined whether an early age of onset of e-cigarette use mediates the association between impulsivity and e-cigarette frequency.

METHODS

Cross-sectional survey data of e-cigarette users (n=927) were collected from 8 high schools in southeastern Connecticut. The sample was 44.7% female (mean age 16.2 [SD=1.2], mean age of e-cigarette onset 14.7 [SD=1.6]). Two domains of self-reported, trait impulsivity were assessed using the abbreviated Barratt Impulsiveness Scale: impaired self-regulation (e.g., problems with concentration or self-control) and behavioral impulsivity (e.g., doing things without thinking). Mediation was tested with Mplus, and the model included school as a cluster variable and controlled for covariates related to e-cigarette use (i.e., sex, age, race, peer use, and other tobacco products ever tried).

RESULTS

The hypothesized mediation was supported for both domains of impulsivity (impaired self-regulation a₁b=0.09, SE=0.02, 95%CI [0.03-0.14], p=.002; behavioral impulsivity a₂b=0.07, SE=0.03, 95%CI [.01-.14], p=0.03). Specifically, impaired self-regulation (B=-0.33, SE=0.06, p<0.001) and behavioral impulsivity (B=-0.26, SE=0.11, p=0.02) predicted trying e-cigarettes at an earlier age, and earlier initiation was associated with more days of e-cigarette use in the past month (B=-0.28, SE=0.08, p<0.001).

CONCLUSIONS

Adolescents who endorse aspects of impulsivity, such as acting without thinking, are at greater risk for more frequent e-cigarette use through an early age of e-cigarette initiation. Further research is needed to evaluate these relationships longitudinally and to develop targeted e-cigarette interventions for impulsive youth.

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.

Examining College Students' Social Environment, Normative Beliefs, and Attitudes in Subsequent Initiation of Electronic Nicotine Delivery Systems

BACKGROUND

Although use of Electronic Nicotine Delivery Systems (ENDS) is increasingly prevalent among young adults, little is known about predictors of ENDS initiation among this population.

AIMS

We examined the roles of the social environment (i.e., peer ENDS use and household ENDS use), normative beliefs (i.e., social acceptability of ENDS use), and attitudes (i.e., inclination to date someone who uses ENDS) in prospectively predicting initiation of ENDS over a 1-year period among 18- to 29-year-old college students.

METHOD

Participants were 2,110 (18- to 29-year-old) students ( M = 20.27, SD = 2.17) from 24 colleges in Texas who participated in a three-wave online survey, with 6 months between each wave. All participants reported never using ENDS at baseline. A multivariable, multilevel logistic regression model, accounting for clustering of students within colleges, was used to assess if students' social environment, normative beliefs, and attitudes predicted subsequent initiation of ENDS up to 1 year later, adjusting for various sociodemographic factors and number of other tobacco products used.

RESULTS

In all, 329 college students (16%) initiated ENDS within 1 year. Results from the logistic regression indicated that college students who were younger (18-24 years old), ever used other tobacco products, indicated a more dense peer network of ENDS users, and had a higher inclination to date someone who uses ENDS had higher odds of initiating ENDS than their peers.

CONCLUSION

Preventing ENDS initiation should be included in college health promotion programs, which should highlight the roles of students' social environment and attitudes regarding ENDS use.

Could Vaping be a New Weapon in the Battle of the Bulge?

IMPLICATIONS

Obesity is set to overtake tobacco smoking in many countries as the primary cause of several high-cost diseases. Tobacco smoking mitigates weight gain through nicotine's effect on the brain and metabolism. Smoking, however, is associated with many illnesses and premature death and appropriately has been discouraged leading to declining prevalence rates. This article explores the emerging perception that vaping electronic cigarettes with nicotine and flavors could deliver similar appetite and weight control effects as smoking. The potential to reduce risks associated with excess weight deserves exploration. An initial research agenda is suggested.

The impact of flavour, device type and warning messages on youth preferences for electronic nicotine delivery systems: evidence from an online discrete choice experiment

OBJECTIVE

To examine the impact of flavour, device type and health warning messages on youth preference for electronic nicotine delivery systems (ENDS), and to provide evidence and data to inform the Food and Drug Administration's potential regulatory actions on ENDS.

DESIGN

An online discrete choice experiment was conducted in September 2015. Each participant was given nine choice sets and asked to choose one out of two alternative ENDS products, with varying characteristics in three attributes (flavour, device type and warning message). The impact of the attributes on the probability of choosing ENDS was analysed using conditional and nested logit regressions, controlling for individual sociodemographic characteristics and current smoking status.

SETTING AND PARTICIPANTS

A general population sample of 515 participants (50 ever-users and 465 never-users of ENDS) aged 14-17 years were recruited to complete the experiment using an online panel.

RESULTS

Fruit/sweets/beverage flavours significantly increase the probability of choosing ENDS among youth (p<0.01 for never-users and <0.1 for ever-users) and flavour has the most pronounced impact among three attributes. Among never-users, menthol flavour also increases (p<0.05) the probability of choosing ENDS compared with tobacco flavour. Vaping devices that are modifiable, compared with cigarette-like e-cigarettes, increase (p<0.05) the probability of choosing ENDS among adolescent never-users. Warning messages reduce (p<0.01) the probability of choosing ENDS among never-users.

CONCLUSIONS AND RELEVANCE

Restricting fruit/sweets/beverage flavours in ENDS, regulating modifiable vaping devices and adopting strong health warning messages may reduce the uptake of ENDS among youth.

Risk Factors for Youth E-Cigarette "Vape Trick" Behavior

PURPOSE

Some adolescent users of e-cigarettes and other electronic vaping products (EVPs) report performing "vape tricks" (exhaling aerosol to make shapes). However, little is known about this behavior. We examined the frequency of performing and watching vape tricks and the characteristics of those most likely to perform vape tricks among a sample of adolescent EVP users.

METHODS

We used social media ads to recruit a national convenience sample of U.S. adolescents (n = 1,729) to participate in an online survey in September 2016. Inclusion criteria required participants to be aged 15-17 years and to have used EVPs at least once in the past 30 days.

RESULTS

The majority of EVP-using adolescents reported trying (77.8%) and watching vape tricks in person (83.7%) or online (74.0%). Risk factors for performing tricks included using advanced vaping devices, vaping every day, white race, moderate levels of seeing and sharing vaping information on social media, and believing that EVP use is more normative among peers. Likelihood of trying vape tricks decreased as beliefs about the harmfulness of EVPs increased.

CONCLUSIONS

Vape tricks pose a potential threat to adolescent health if they encourage nonusers to initiate or current EVP users to use more frequently or switch to advanced devices that produce more harmful chemical emissions. Further research should examine the possible health effects of performing vape tricks, and future public health campaigns should be informed by an understanding of the appeal of this activity for adolescents.

Electronic Cigarette Smoke Impairs Normal Mesenchymal Stem Cell Differentiation

Electronic cigarettes (e-cigarettes) are promoted as low-risk alternatives to combustible cigarettes. However, the effects of chronic inhalation of potential toxicants emitted by ecigarettes remain largely unexamined. It is conceivable that smoking-induced chronic diseases result in cellular injury, in the absence of effective repair by stem cells. This study evaluates the effect of cigarette and e-cigarette aerosol extracts on the survival and differentiation of bone marrow-derived mesenchymal stem cells (MSCs). MSC growth and osteogenic differentiation were examined after exposure to smoke extracts. Data revealed detrimental effects of both cigarette and e-cigarette extracts on MSC morphology and growth. Levels and activity of alkaline phosphatase, an osteogenic marker, decreased and induction of osteoblastic differentiation was impaired. Both smoke extracts prevented osteogenic differentiation from progressing, evident by decreased expression of terminal osteogenic markers and mineralization. Elevated levels of reactive oxygen species (ROS) were detected in cells exposed to smoke extracts. Moreover, decreased differentiation potential was concomitant with severe down-regulation of Connexin 43 expression, leading to the loss of gap junction-mediated communication, which together with elevated ROS levels, could explain decreased proliferation and loss of differentiation potential. Hence, e-cigarettes present similar risk as combustible cigarettes with respect to tissue repair impairment.

Frequency of E-cigarette Use, Health Status, and Risk and Protective Health Behaviors in Adolescents

OBJECTIVES

E-cigarettes (ECs) are increasingly popular among adolescents, who perceive them as "safer" than cigarettes. Although research has examined risk factors for adolescent EC use, little is known about how EC use correlates with health status and protective health behaviors.

METHODS

In all, 2488 adolescents (mean age = 17.31 years, SD = 0.67; 46% male) completed a survey on EC and cigarette use, physical and mental health, physical activity, diet, sleep, and alcohol and other drug (AOD) use. Logistic regression compared EC-only users to dual EC/cigarette users, cigarette-only users, and nonusers on these health factors. Among EC-only users, separate ordinary least-squares regression models assessed the effects of health status/behavior variables on frequency of past-year EC use, controlling for demographics and smokeless tobacco use.

RESULTS

User groups were similar on physical health and engagement in protective health behaviors (physical activity, sleep duration/quality, healthy diet), but EC-only users reported fewer mental health symptoms and less AOD use than dual or cigarette-only users. Among EC-only users, AOD use (all P < 0.0001) predicted more frequent EC use; healthy diet predicted less frequent use (P < 0.01).

CONCLUSIONS

EC-only use is associated with lower engagement in risky behaviors, but not better health status or higher engagement in protective health behaviors, compared with cigarette smoking. Dual EC/cigarette users may represent a particularly high-risk group due to their greater AOD use and cigarette consumption. Among "intermediate-risk" EC-only users, AOD use and unhealthy diet correlated with heavier use, and may be important targets for preventing escalation to more harmful tobacco use.

Electronic Cigarettes: Their Constituents and Potential Links to Asthma

PURPOSE OF REVIEW

Vaping is gaining popularity in the USA, particularly among teens and young adults. While e-cigs are commonly represented as safer alternatives to tobacco cigarettes, little is known regarding the health effects of their short- or long-term use, especially in individuals with pre-existing respiratory diseases such as asthma. Flavored e-cig liquids (e-liquids) and e-cig aerosols contain airway irritants and toxicants that have been implicated in the pathogenesis and worsening of lung diseases. In this review, we will summarize existing data on potential health effects of components present in e-cig aerosols, such as propylene glycol, vegetable glycerin, nicotine, and flavorings, and discuss their relevance in the context of asthma.

RECENT FINDINGS

Recent survey data indicate that adolescents with asthma had a higher prevalence of current e-cig use (12.4%) compared to their non-asthmatics peers (10.2%) and conveyed positive beliefs about tobacco products, especially e-cigs. Similarly, a study conducted among high school students from Ontario, Canada, indicated a greater likelihood of e-cig use in asthmatics as compared to their non-asthmatic peers. Availability of different flavorings is often cited as the main reason among youth/adolescents for trying e-cigs or switching from cigarettes to e-cigs. Occupational inhalation of some common food-safe flavoring agents is reported to cause occupational asthma and worsen asthmatic symptoms. Moreover, workplace inhalation exposures to the flavoring agent diacetyl have caused irreversible obstructive airway disease in healthy workers. Additionally, recent studies report that thermal decomposition of propylene glycol (PG) and vegetable glycerin (VG), the base constituents of e-liquids, produces reactive carbonyls, including acrolein, formaldehyde, and acetaldehyde, which have known respiratory toxicities. Furthermore, recent nicotine studies in rodents reveal that prenatal nicotine exposures lead to epigenetic reprogramming in the offspring, abnormal lung development, and multigenerational transmission of asthmatic-like symptoms. Comparisons of the toxicity and health effects of e-cigs and conventional cigarettes often focus on toxicants known to be present in cigarette smoke (CS) (i.e., formaldehyde, nitrosamines, etc.), as well as smoking-associated clinical endpoints, such as cancer, bronchitis, and chronic obstructive pulmonary disease (COPD). However, this approach disregards potential toxicity of components unique to flavored e-cigs, such as PG, VG, and the many different flavoring chemicals, which likely induce respiratory effects not usually observed in cigarette smokers.