Inflammatory biomarker changes in healthy adults secondary to electronic cigarette use: A scoping review

CONTEXT

There has been a global increase in the use of electronic cigarettes (EC). However, to our knowledge, no review has summarized or categorized changes in inflammatory biomarkers after EC use in the extant literature.

OBJECTIVE

To evaluate changes in general, cardiopulmonary, and oxidative stress-related inflammatory biomarkers in healthy adults who use ECs.

METHODS

A scoping review was conducted according to the Arksey and O'Malley framework. PubMed and MEDLINE (Ovid) databases were used for our search. After initial pilot searches and discussions, we performed a final search with medical subject headings and plain language terms related to inflammation, biomarkers, ECs, and adult humans. All full-text articles, gray literature, and primary studies dating from the inception of the searched databases to the present were included. Studies of human participants with known confounding medical histories were excluded.

RESULTS

Thirty-seven studies met the inclusion criteria. After short-term (<1 month) use, ECs containing nicotine moderately increased cardiovascular (CV) and oxidative stress markers of inflammation. Of all reported results, 50% of CV biomarkers were increased, and 64% of oxidative stress markers were increased. After long-term (>1 month) use, ECs containing nicotine produced mixed results. Two commonly measured biomarkers in this group, matrix metalloproteinase-9 (MMP-9) and interleukin-6 (IL-6), were elevated in 75% and 60% of measured instances, respectively.

CONCLUSION

The results of studies evaluated in our scoping review suggested that short-term use of nicotine-containing ECs may result in increased CV and oxidative stress inflammation, contributing to potential CV or neurologic disease development. The results of studies evaluated in our scoping review also suggested that long-term use of nicotine-containing ECs resulted in no significant changes in general inflammatory biomarker levels. A rigorous systematic review and meta-analysis is necessary to corroborate our findings and to determine the effect of long-term EC use on MMP-9 and IL-6 levels.

E-cigarettes may serve as a gateway to conventional cigarettes and other addictive drugs

Electronic cigarettes (e-cigarettes) are devices that allow the user to inhale nicotine in a vapor, and are primarily marketed as a means of quitting smoking and a less harmful replacement for traditional cigarette smoking. However, further research is needed to determine if vaping nicotine via e-cigarettes can be effective. Conversely, nicotine has been considered a gateway drug to alcohol and other addictive drugs and e-cigarettes containing nicotine may have the same effects. Previous reports have shown that e-cigarette use may open the gate for the use of other drugs including conventional cigarettes, cannabis, opioids, etc. The increasing prevalence of e-cigarettes, particularly among youth and adolescents in the last decade have led to an increase in the dual use of e-cigarettes with alcohol, cannabis, and other illicit drug use like heroin and 3-4-methylenedioxymethamphetamine (MDMA). The advent of e-cigarettes as a device to self-administer addictive agents such as cocaine and synthetic cathinones may bring about additional adverse health effects associated with their concurrent use. This review aims to briefly describe e-cigarettes and their different generations, and their co-use with other addictive drugs as well as the use of the device as a tool to self-administer addictive drugs, such as cocaine, etc.

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

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

Toxicological assessment of electronic cigarette vaping: an emerging threat to force health, readiness and resilience in the U.S. Army

The U.S. Army and U. S. Army Public Health Center are dedicated to protecting the health, and readiness of Department of the Army Service Members, civilians, and contractors. Despite implementation of health programs, policies and tobacco control interventions, the advent of electronic nicotine delivery systems (ENDS), including electronic cigarettes (e-cigs), represent unregulated and poorly defined systems to supplant or substitute use of conventional nicotine products (e.g., cigarettes and pipe tobacco). E-cigs present unique challenges to healthcare officials vested in preventive medicine. The health impact of an e-cig and vaping on an individual's acute or chronic disease susceptibility, performance and wellness, is fraught with uncertainty. Given the relatively recent emergence of e-cigs, high-quality epidemiological studies, and applied biological research studies are severely lacking. In sparsely available epidemiological studies of short-term cardiovascular and respiratory health outcomes, any attempt at addressing the etiology of acute and chronic health conditions from e-cig use faces incredible challenges. Until relatively recently, this was complicated by an absent national regulatory framework and health agency guidance on the manufacture, distribution, selling and use of e-cigs or similar ENDS devices and their chemical constituents. Two key issues underpin public health concern from e-cig use: 1) continued or emergent nicotine addiction and potential use of these devices for vaping controlled substances; and 2) inadvertent sudden-onset or chronic health effects from inhalational exposure to low levels of complex chemical toxicants from e-cig use and vaping the liquid. Herein, the health impacts from e-cig vaping and research supporting such effects are discussed.

Surveillance of U.S. Corporate Filings Provides a Proactive Approach to Inform Tobacco Regulatory Research Strategy

The popularity of electronic cigarettes in the United States and around the world has led to a startling rise in youth nicotine use. The Juul® e-cigarette was introduced in the U.S. market in 2015 and had captured approximately 13% of the U.S. market by 2017. Unlike many other contemporary electronic cigarette companies, the founders behind the Juul® e-cigarette approached their product launch like a traditional high-tech start-up company, not like a tobacco company. This article presents a case study of Juul's corporate and product development history in the context of US regulatory actions. The objective of this article is to demonstrate the value of government-curated archives as leading indicators which can (a) provide insight into emergent technologies and (b) inform emergent regulatory science research questions. A variety of sources were used to gather data about the Juul® e-cigarette and the corporations that surround it. Sources included government agencies, published academic literature, non-profit organizations, corporate and retail websites, and the popular press. Data were disambiguated, authenticated, and categorized prior to being placed on a timeline of events. A timeline of four significant milestones, nineteen corporate filings and events, twelve US regulatory actions, sixty-four patent applications, eighty-seven trademark applications, twenty-three design patents and thirty-two utility patents related to Juul Labs and its associates is presented, spanning the years 2004 through 2020. This work demonstrates the probative value of findings from patent, trademark, and SEC filing literature in establishing a premise for emergent regulatory science research questions which may not yet be supported by traditional archival research literature. The methods presented here can be used to identify key aspects of emerging technologies before products actually enter the market; this shifting policy formulation and problem identification from a paradigm of being reactive in favor of becoming proactive. Such a proactive approach may permit anticipatory regulatory science research and ultimately shorten the elapsed time between market technology innovation and regulatory response.

Electronic Cigarette-Related Contents on Instagram: Observational Study and Exploratory Analysis

Background

Instagram is a popular social networking platform for users to upload pictures sharing their experiences. Instagram has been widely used by vaping companies and stores to promote electronic cigarettes (e-cigarettes), as well as by public health entities to communicate the risks of e-cigarette use (vaping) to the public.

Objective

We aimed to characterize current vaping-related content on Instagram through descriptive analyses.

Methods

From Instagram, 42,951 posts were collected using vaping-related hashtags in November 2019. The posts were grouped as (1) pro-vaping, (2) vaping warning, (3) neutral to vaping, and (4) not related to vaping based on the attitudes to vaping expressed within the posts. From these Instagram posts and the corresponding 18,786 unique Instagram user accounts, 200 pro-vaping and 200 vaping-warning posts as well as 200 pro-vaping and 200 vaping-warning user accounts were randomly selected for hand coding. Furthermore, follower counts and media counts of the Instagram user accounts as well as the “like” counts and hashtags of the posts were compared between pro-vaping and vaping-warning groups.

Results

There were more posts in the pro-vaping group (41,412 posts) than there were in the vaping-warning group (1539 posts). The majority of pro-vaping images were product display images (163/200, 81.5%), and the most popular image type in vaping-warning posts was educational (95/200, 47.5%). The highest proportion of pro-vaping user account type was vaping store (110/189, 58.1%), and the store account type had the highest mean number of posts (10.33 posts/account). The top 3 vaping-warning user account types were personal (79/155, 51%), vaping-warning community (37/155, 23.9%), and community (35/155, 22.6%), of which the vaping-warning community had the highest mean number of posts (3.68 posts/account). Pro-vaping user accounts had more followers (median 850) and media (median 232) than vaping-warning user accounts had (follower count: median 191; media count: 92). Pro-vaping posts had more “likes” (median 22) and hashtags (mean 20.39) than vaping-warning posts had (“like” count: median 12; hashtags: mean 7.16).

Conclusions

Instagram is dominated by pro-vaping content, and pro-vaping posts and user accounts seem to have more user engagement than vaping-warning accounts have. These results highlight the importance of regulating e-cigarette posts on social media and the urgency of identifying effective communication content and message delivery methods with the public about the health effects of e-cigarettes to ameliorate the epidemic of vaping in youth.

Investigating the Attitudes of Adolescents and Young Adults Towards JUUL: Computational Study Using Twitter Data

Background

Increases in electronic nicotine delivery system (ENDS) use among high school students from 2017 to 2019 appear to be associated with the increasing popularity of the ENDS device JUUL.

Objective

We employed a content analysis approach in conjunction with natural language processing methods using Twitter data to understand salient themes regarding JUUL use on Twitter, sentiment towards JUUL, and underage JUUL use.

Methods

Between July 2018 and August 2019, 11,556 unique tweets containing a JUUL-related keyword were collected. We manually annotated 4000 tweets for JUUL-related themes of use and sentiment. We used 3 machine learning algorithms to classify positive and negative JUUL sentiments as well as underage JUUL mentions.

Results

Of the annotated tweets, 78.80% (3152/4000) contained a specific mention of JUUL. Only 1.43% (45/3152) of tweets mentioned using JUUL as a method of smoking cessation, and only 6.85% (216/3152) of tweets mentioned the potential health effects of JUUL use. Of the machine learning methods used, the random forest classifier was the best performing algorithm among all 3 classification tasks (ie, positive sentiment, negative sentiment, and underage JUUL mentions).

Conclusions

Our findings suggest that a vast majority of Twitter users are not using JUUL to aid in smoking cessation nor do they mention the potential health benefits or detriments of JUUL use. Using machine learning algorithms to identify tweets containing underage JUUL mentions can support the timely surveillance of JUUL habits and opinions, further assisting youth-targeted public health intervention strategies.

Vaping effects on asthma: results from a web survey and clinical investigation

It is well known that tobacco smoking worsens asthma. Conversely, few data are currently available in the literature on the effects of vaping in asthmatic patients. This work aims to investigate the effects of vaping on asthmatic patients and in asthmatic patients that switched from tobacco smoking to electronic cigarette (e-cig), in particular focusing on quality of life, asthma control, and pulmonary function. We designed a two-group study. One group encompassed vapers with asthma selected through a web survey with questions on quality of life and symptoms worsening; the other group encompassed vapers that switched from tobacco smoking to e-cig, and that volunteered to undergo clinical visits at our outpatient clinic. 2787 people responded to the web survey, including 631 asthmatics. In the second group, 55 volunteers, including 15 asthmatics, were enrolled after a visit. The visit included physical examination and pulmonary function tests (PFT). Internationally validated questionnaires were administered to all subjects: Asthma Control Test (ACT), Asthma Control Questionnaire (ACQ), 36-Item Short Form Survey (SF-36) and Asthma Quality of Life Questionnaire (AQLQ). The 382 asthmatic vapers-only in the web survey were mainly males (86.9%), 31-65 years old. 90% of them declared that vaping did not worsen asthma symptoms and would recommend asthmatic smokers to switch to vaping (98.4%). There was worsening of asthma symptoms due to the actual asthma therapy used by the participants, while no relationship was found with other aspects analysed. In the second group, the analysis of variance in the questionnaires administered to the 10 asthmatics showed a significant improvement in ACQ, ACT and SF-36 for asthmatics that switched from tobacco to vaping, while PFT remained stable throughout the three visits. Almost all of the asthmatics who previously smoked would recommend switching to e-cig, and vaping did not worsen their asthma symptoms. Furthermore, switching from tobacco smoking to e-cigs showed a significant improvement in asthma control and quality of life, not showing, in the period studied, to affect pulmonary function tests.

An Analysis of Associations Between Electronic Nicotine Delivery System Users

BACKGROUND

Electronic nicotine-delivery systems have been increasing in prevalence among young adults. Although these devices are marketed to aid in quit smoking, young adults who do not smoke traditional cigarettes are using these devices. This study explored associations between individuals' quit type (ie, no plans to quit, plans to quit, or quit > 6 months ago) and perceived health status, perception of harm compared to cigarettes, perception of secondhand vapor harm, and reasons for first use.

METHODS

We utilized a cross-sectional study design using a 33-item electronic survey questionnaire. The total sample size was 2,792. Out of these the ENDS users were 1,217. The survey was distributed to university students in 5 areas in 3 countries: the United States (ie, Florida, Alabama, and Illinois), Germany (ie, Hamburg) and South Africa (ie, Potchefstroom).

RESULTS

Quantitative data analysis indicated that, regardless of quit status, there was a general lack of knowledge regarding secondhand vapor effects. Additionally, young adults are utilizing these products primarily due to peer influence and stress relief. Harm perception may factor into quit attempts using electronic nicotine-delivery systems.

CONCLUSIONS

Education provided by respiratory therapists (and to respiratory therapy students) would be valuable as they inform patients and communities of the scholarly literature on vaping devices.

Generally Recognized as Safe: Uncertainty Surrounding E-Cigarette Flavoring Safety

Despite scientific uncertainty regarding the relative safety of inhaling e-cigarette aerosol and flavorings, some consumers regard the U.S. Food and Drug Administration’s “generally recognized as safe” (GRAS) designation as evidence of flavoring safety. In this study, we assessed how college students’ perceptions of e-cigarette flavoring safety are related to understanding of the GRAS designation. During spring 2017, an online questionnaire was administered to college students. Chi-square p-values and multivariable logistic regression were employed to compare perceptions among participants considering e-cigarette flavorings as safe and those considering e-cigarette flavorings to be unsafe. The total sample size was 567 participants. Only 22% knew that GRAS designation meant that a product is safe to ingest, not inhale, inject, or use topically. Of participants who considered flavorings to be GRAS, the majority recognized that the designation meant a product is safe to ingest but also considered it safe to inhale. Although scientific uncertainty on the overall safety of flavorings in e-cigarettes remains, health messaging can educate the public about the GRAS designation and its irrelevance to e-cigarette safety.

The Theory of Planned Behavior and E-cig Use: Impulsive Personality, E-cig Attitudes, and E-cig Use

The current paper applied the Theory of Planned Behavior (TPB; Ajzen & Fishbein, 1988) to understand how impulsive personality traits and attitudes concerning e-cig use relate to the likelihood of electronic cigarette (e-cig) use. Seven hundred and fourteen participants (Mean age = 34.04, SD = 10.89, 48.6% female) completed cross-sectional measures of e-cig use attitudes (CEAC) and the Short UPPS-P Impulsive Behavior Scale. A structural path analysis suggested that urgency and deficits in conscientiousness were significantly related to e-cig attitudes (CFI = 0.99, TLI = 0.99, RMSEA = 0.02; urgency: β = 0.32, p = .001; deficits in conscientiousness: β = -0.48, p < .001). E-cig attitude scores were significantly higher for e-cig users than non-users, β = 0.85, p < .001. There was no significant direct path from impulsive personality traits to e-cig use. Findings provide initial support for a model in which impulsive traits are related to e-cig use through positive e-cig attitudes.

Universal electronic-cigarette test: physiochemical characterization of reference e-liquid

BACKGROUND

Despite the rising health and safety concerns of e-cigarettes, a universal e-cigarette testing method is still in its early developmental stage. The aim of this study was to develop an e-liquid Reference Material that can be used to improve accuracy and reproducibility of research results, and advance health risk assessment of e-cigarette products.

METHODS

E-liquid Reference Material was developed by purity assessment, gravimetric measurement, homogeneity testing, and stability testing with material and instrument traceability (adopted from ISO 35:2006E).

RESULTS

Homogeneity tests showed e-liquid Reference Material requires ≥ 1 h rotation at a speed of 5 rpm to reach complete homogeneity. Stability tests showed homogeneity is intact for at least 2 weeks without secondary separation, and e-liquids are stable in 21 °C-50 °C thermocycling conditions up to 72 h. A change in the e-liquid color was first observed at day seven, and progressed to 2- and 16 - fold increase in absorbance by one and 6 months respectively. We found that e-liquids do not have inherent material instabilities such as immiscibility or secondary separation. However, discrepancies in concentration and composition arose mainly due to viscosity of propylene glycol and glycerin. Aerosol generated from the e-liquid Reference Material had 16 chemical-byproducts and was composed of ~634,000 particles of which 38% were Fine Particulate Matters (<0.5 μm in diameter).

CONCLUSIONS

The efforts described here to create a standardized e-liquid Reference Material aim to provide unbiased and robust testing parameters that may be useful for researchers, the industry and government agencies. Additionally, the reference e-liquid could open a channel of conversation among different laboratories by providing the means of independent verification and validation while establishing a system of transparency and reproducibility in materials and methods.

The Importance of Conditioned Stimuli in Cigarette and E-Cigarette Craving Reduction by E-Cigarettes

This study examined the impact of four variables pertaining to the use of e-cigarettes (e-cigs) on cravings for tobacco cigarettes and for e-cigs after an overnight abstinence period. The four variables were the nicotine level, the sensorimotor component, the visual aspect, and the aroma of the e-cig. In an experimental study, 81 participants without prior vaping experience first got acquainted with using e-cigs in a one-week tryout period, after which they participated in a lab session assessing the effect of five minutes of vaping following an abstinence period of 12 h. A mixed-effects model clearly showed the importance of nicotine in craving reduction. However, also non-nicotine factors, in particular the sensorimotor component, were shown to contribute to craving reduction. Handling cues interacted with the level (presence/absence) of nicotine: it was only when the standard hand-to-mouth action cues were omitted that the craving reducing effects of nicotine were observed. Effects of aroma or visual cues were not observed, or weak and difficult to interpret, respectively.

Electronic Cigarettes and Communication: An Examination of College Students' Perceptions of Safety and Use

Electronic cigarettes (e-cigs) have increased in popularity over the last few years, especially with youth and young adults. However, little is known about the health effects of using these devices. Additionally, relatively few studies have explored college students' e-cig use and perceptions of safety. In this study, perceptions of e-cig safety were compared among three groups of college students-those who had never tried, had tried, and currently use e-cigs. Study findings suggest interesting differences between the three groups, with participants who had tried as well as those who currently use e-cigs having more positive views of the devices. For example, current users were more likely to view e-cigs as safe and healthy choices and less likely to view them as tobacco products. Further, compared to participants who had not tried e-cigs, individuals who had tried or currently use e-cigs were more likely to believe that vapor was safe to others (i.e., no second- or third-hand effects). Understanding the perceptions and use of e-cigs among college students is important in order to develop communication strategies for anti-tobacco campaigns that effectively relate safety concerns to these audiences.

A C. elegans model of electronic cigarette use: Physiological effects of e-liquids in nematodes

BACKGROUND

Electronic cigarettes (e-cigs) have recently become very popular particularly among the younger generation. These nicotine delivery devices are viewed as a preferable alternative to more conventional forms of tobacco use and are thought to reduce the risk of chronic obstructive pulmonary disease, the third leading cause of death worldwide. However, there is very little data available on the consequences of e-cig use, though recently nicotine-independent inflammatory responses have been reported. The genetic model organism Caenorhabditis elegans is a soil nematode whose cell biology is remarkably well conserved with mammals. Here, we used C. elegans to test the physiologic effects of e-liquids used to refill e-cigs.

METHODS

Larval worms were exposed from hatching onwards to low concentrations (0.2 %) of e-liquids, distilled e-liquid vapor, propylene glycol (PG), or M9 buffer as a negative control. E-liquids tested included grape, menthol, and V2 Red "classic tobacco" flavors. Nicotine (48 ppm) was tested as a second level variable. Stereotypical physiological outputs were then measured, including developmental rate, fecundity, locomotion, lifespan, and the induction of canonical stress signaling pathways.

RESULTS

A small but significant impairment of developmental rate and brood size was observed for PG and V2 Red treated worms compared to the negative control. Worms treated with e-liquids containing nicotine fared significantly worse than those that did not, but vaporization did not increase toxicity. Finally, both PG and V2 Red e-liquid induced an oxidative stress response in the absence of nicotine.

CONCLUSIONS

PG exposure is sufficient to induce an oxidative stress response in nematodes, while nicotine is not. Both PG and nicotine independently influence physiologic measures of health and viability. The e-liquid flavorings did not significantly impact outcomes and there was no evidence for vaporization altering toxicity. These data suggest that the major physiologically significant component of e-liquids besides nicotine is likely the common solvent PG. We conclude that C. elegans are an appropriate model to rapidly assess parameters that may contribute to the basic cell biological effects of e-cigs.

Current and future trends in electronic cigarette use

The controversy regarding the use of electronic cigarettes as a possible modality for smoking cessation has grown in recent years. Epidemiologic surveys indicate that usage rates in both adults and adolescents have increased substantially as the popularity of these devices continues to rise. At present, there is a small but growing body of evidence studying the possible role that these "e-cigarettes" may have as a nicotine replacement tool. Much of the existing data are from observational studies and surveys which track the epidemiologic and demographic trends of e-cigarette users. More recently-published articles have begun to utilize randomized, experimental designs to directly compare the efficacy of e-cigarettes to active and passive controls in outcome measures such as conventional cigarette quit rates and time to relapse. Barriers to widespread adoption of e-cigarette use as a smoking cessation modality include a lack of long-term safety and toxicology data, a lack of standardization of devices, and a debate regarding whether devices can be marketed for both social nicotine use, as well as nicotine replacement. A possible role of e-cigarettes that has not yet been explored is in the primary prevention of conventional cigarette use among young adults that are smoking-naïve.