Profile of incidental exposures to e-cigarette liquids in Europe, 2018-2019

BACKGROUND

Following the implementation of the European Union Tobacco Product Directive (EU TPD) regulations on e-cigarette products in 2016, we assessed the current profile of e-cigarette liquid exposure incidents and their associated health outcomes.

METHODS

De-identified data were received from poison centers in eight EU Member States (Sweden, the Netherlands, Italy, Hungary Austria, Finland, Spain and Croatia) reporting on e-cigarette liquid exposure incidents between August 2018 to December 2019. Descriptive analysis was conducted to present incident characteristics and health outcomes. Chi-square tests and multivariable logistic regression analysis were used to test associations.

RESULTS

Of the 223 e-liquid exposure incidents recorded by poison centers in multiple EU MS, 64.7% of the cases were unintentional exposures, ranging from 48.4% among adults aged ≥19 years to 100.0% among children aged 0-5 years (p < 0.05). The most frequent route of exposure was ingestion (73.5%) while55.2% experienced any clinical symptoms, including nausea (16.6%), vomiting (11.1%), and dizziness (9.0%). 57.8% of the cases were treated at the residence or on-site.

CONCLUSION

Further monitoring is warranted, using uniform reporting requirements, to ensure the continued compliance to the EU TPD and assess its long-term impact on related incident characteristics.

E-Liquid Containing a Mixture of Coconut, Vanilla, and Cookie Flavors Causes Cellular Senescence and Dysregulated Repair in Pulmonary Fibroblasts: Implications on Premature Aging

Electronic cigarette (e-cig) usage has risen dramatically worldwide over the past decade. While they are touted as a safe alternative to cigarettes, recent studies indicate that high levels of nicotine and flavoring chemicals present in e-cigs may still cause adverse health effects. We hypothesized that an e-liquid containing a mixture of tobacco, coconut, vanilla, and cookie flavors would induce senescence and disrupt wound healing processes in pulmonary fibroblasts. To test this hypothesis, we exposed pulmonary fibroblasts (HFL-1) to e-liquid at varying doses and assessed cytotoxicity, inflammation, senescence, and myofibroblast differentiation. We found that e-liquid exposure caused cytotoxicity, which was accompanied by an increase in IL-8 release in the conditioned media. E-liquid exposure resulted in elevated senescence-associated beta-galactosidase (SA-β-gal) activity. Transforming growth factor-β1 (TGF-β1) induced myofibroblast differentiation was inhibited by e-liquid exposure, resulting in decreased α-smooth muscle actin and fibronectin protein levels. Together, our data suggest that an e-liquid containing a mixture of flavors induces inflammation, senescence and dysregulated wound healing responses.

Brain death following ingestion of E-cigarette liquid nicotine refill solution

BACKGROUND

The use of electronic cigarettes (e-cigarettes) is very common worldwide. To date, an increase of nicotine intoxication following an accidental or intentional ingestion/injection of refill solution (e-liquid) has been detected.

CASE

A 23-year-old man presented with sudden loss of consciousness, bradycardia, and respiratory muscle paralysis after intentional ingestion of e-liquid. Early clinical data, brain computed tomography, and neurophysiological tests (electroencephalogram [EEG] and somatosensory evoked potentials [SEPs]) did not show features with a poor neurological prognostic meaning of an hypoxic encephalopathy. After 4 days, the patient showed bilateral loss of the pupillary reflex, and severe and cytotoxic edema was detected on brain magnetic resonance imaging. SEPs showed a bilateral loss of cortical responses and EEG a suppressed pattern. Nine days after the onset of coma, the patient evolved toward brain death (BD).

DISCUSSION

Because nicotine intoxication might cause respiratory muscle paralysis, without cardiac arrest (CA), it would be important to understand the mechanisms underlying brain damage and to take into account that the current neurological prognostic evidence for hypoxic-ischemic encephalopathy, based on data from patients who all experienced CA may not be reliable. Reporting cases of nicotine intoxication through e-liquid is relevant in order to improve regulatory parameters for e-liquid sale.

The Impact of Device Settings, Use Patterns, and Flavorings on Carbonyl Emissions from Electronic Cigarettes

Health impacts of electronic cigarette (e-cigarette) vaping are associated with the harmful chemicals emitted from e-cigarettes such as carbonyls. However, the levels of various carbonyl compounds under real-world vaping conditions have been understudied. This study evaluated the levels of carbonyl compounds (e.g., formaldehyde, acetaldehyde, glyoxal, and diacetyl, etc.) under various device settings (i.e., power output), vaping topographies, and e-liquid compositions (i.e., base liquid, flavor types). The results showed that e-vapor carbonyl levels were the highest under higher power outputs. The propylene glycol (PG)-based e-liquids generated higher formaldehyde and acetaldehyde than vegetable glycerin (VG)-based e-liquids. In addition, fruit flavored e-liquids (i.e., strawberry and dragon fruit) generated higher formaldehyde emissions than mint/menthol and creamy/sweet flavored e-liquids. While single-top coils formed 3.5-fold more formaldehyde per puff than conventional cigarette smoking, bottom coils generated 10-10,000 times less formaldehyde per puff. In general, increases in puff volume and longer puff durations generated significantly higher amounts of formaldehyde. While e-cigarettes emitted much lower levels of carbonyl compounds compared to conventional cigarettes, the presence of several toxic carbonyl compounds in e-cigarette vapor may still pose potential health risks for users without smoking history, including youth. Therefore, the public health administrations need to consider the vaping conditions which generated higher carbonyls, such as higher power output with PG e-liquid, when developing e-cigarette product standards.

Modifications to Electronic Nicotine Delivery Systems: Content Analysis of YouTube Videos

BACKGROUND

As user modification can alter the addictiveness and toxicity of electronic nicotine delivery systems (ENDS), more research is needed to understand the types, motivations, risks, and information sources that lead to these product alterations. YouTube has been identified as a major platform where ENDS users obtain and share information about ENDS products and modifications. However, a comprehensive study of ENDS modification videos on YouTube is lacking.

OBJECTIVE

This study aimed to analyze the content of YouTube videos depicting modifications of ENDS.

METHODS

YouTube was searched in March 2019 to identify videos depicting ENDS modifications. Search terms were derived from interviews with ENDS users and current literature. We used 28 search phrases that combined the words vape and vaping with modification-related key terms (eg, custom build, modification, and dripping). The final sample included 168 videos.

RESULTS

Videos were 1 to 108 min long (median 9.55). Presenters were largely male (117/168, 69.6%), white (94/168, 56.0%), and older than 25 years (94/168, 56.0%). Most videos gave how to instructions (148/168, 88.1%), but few offered warnings (30/168, 17.9%) or mentioned commercial alternatives to modifications they presented (16/168, 9.5%). The ENDS devices most often featured were drippers (63/168, 37.5%) and refillable tanks (37/168, 22.0%). The most often modified ENDS components were coils (82/168, 48.8%) and e-liquids (34/168, 20.2%), which included adding other substances, such as cannabis, to the e-liquids (6/168, 3.6%). Most videos portrayed ENDS modifications positively (106/168, 63.1% positive; 60/168, 35.7% neutral; and 2/168, 1.2% negative) and were either neutral or positive in their overall portrayal of ENDS devices (78/168, 46.4% positive; 89/168, 53.0% neutral; and 1/168, 0.6% negative).

CONCLUSIONS

This study identified several concerning trends in popular YouTube videos on ENDS modifications, including lack of warnings, the addition of marijuana derivatives to e-liquids, and the positive portrayal of ENDS devices and modifications. By identifying the types of modifications (coil and e-liquid being the most prevalent), this study sets an agenda for research on the effects of modifications.

Vaping in adolescents: epidemiology and respiratory harm

PURPOSE OF REVIEW

This review highlights epidemiologic changes in e-cigarette use in adolescents, discusses recent advances in aerosolized nicotine delivery, and provides and updated profile of research related to the lung-specific harm of e-cigarettes.

RECENT FINDINGS

In the past decade, nicotine-containing e-cigarettes have emerged as the most popular tobacco and nicotine delivery modality among adolescents in the United States. The surge in popularity of these devices has coincided with an outbreak of vaping-related lung injury, bringing e-cigarette use to national attention, and creating a great deal of confusion regarding their potential for respiratory harm. Newer pod-based devices and formulations of e-liquids have resulted in products appeal to youth and deliver nicotine with increasing efficiency. E-liquid aerosols are associated with direct harm to respiratory epithelium and have been shown to alter pulmonary function, inflammation, mucociliary clearance, and lung histology.

SUMMARY

Although the long-term harms of regular e-cigarette use are unknown, numerous studies including early longitudinal data suggest e-cigarette use is associated with incidence of respiratory disease, independent of concurrent traditional cigarette use. Improved understanding and recognition of harm will contribute to the basis of further studies examining the role of e-cigarettes on chronic respiratory disease and will inform future prevention education.

Acute exposures to e-cigarettes and heat-not-burn products reported to the Czech Toxicological Information Centre over a 7-year period (2012-2018)

E-cigarettes and heat-not-burn cigarettes (HNBC) present new health risks due to their rising popularity, high content of nicotine and serious adverse effects. The objective of the study was to analyse the cases of acute exposure to e-cigarettes, e-liquids and HNBC products containing nicotine that led to toxicological consultations at our poisons control centre during a 7-year period (2012-2018) and identify the categories of special concern that require further investigation and intervention. The demographic, toxicological and clinical data were analysed by descriptive statistics. Poisoning severity score (PSS) was estimated. From 119 229 consultations, 148 cases concerned acute exposure to e-cigarettes. Children and adolescents were exposed in 91 (61%) cases, including exposure of neonates and infants in 54 (36%) cases. The main route of exposure was ingestion in 129 (87%), inhalation in nine (6%), ocular in six (4%) and intravenous administration in three (2%) cases. The source of exposure was the cartridge with e-liquid (107; 72%), refillable tank in 29 (20%) and HNBC refill in nine (6%) cases. The reason for exposure was accidental in 110 (74%), incorrect application of the device in 10 (7%), abuse in six (4%), suicide attempt in six (4%) and other/unknown in 16 (11%) cases. The dose estimation was severe/lethal in 6 (4%), toxic in 53 (36%), low-to-moderate in 35 (24%) and unknown in 54 (36%) cases. Vomiting was observed in 38 (26%) patients; 72% of patients were hospitalised. In symptomatic cases, 41 patient had PSS 1, 12 patients had PSS 2, and one patient had PSS 3. Activated charcoal was applied in 57 (39%) patients, and symptomatic treatment was recommended in 75 (51%) patients. Cases of unintentional exposure of children demonstrate the need for preventive risk reduction measures.

The influence of waste from electronic cigarettes, conventional cigarettes and heat-not-burn tobacco products on microorganisms

Tobacco smoking, especially conventional cigarettes, is widespread throughout the world. Simultaneously, there is a growing interest in new alternative products that allow delivering nicotine to the users' organisms, including electronic cigarettes and heat-not-burn tobacco products. However, there are few scientific reports regarding the effect of waste generated from the above-mentioned products on microorganisms. The aim of the manuscript was to investigate the influence of substances leached from conventional cigarette butts, butts from heat-not-burn tobacco products, cartridges and e-liquids for electronic cigarettes on microorganisms. The commercial multispecies MARA (microbial assay for risk assessment) test and non-selected microorganisms from the Brynica River (Poland), as well as an effluent from the wastewater treatment plant (Sosnowiec-Zagórze, Poland), were used in the ecotoxicity assessment of the investigated waste. The results of the experiments revealed that the waste from electronic cigarettes, i.e. cartridges and e-liquids, does not pose a considerable threat to the microbiocenosis. On the other hand, a particularly strong ecotoxic effect on the investigated microorganisms has been reported for leachate from smoked cigarette butts and butts from heat-not-burn tobacco products. Their high ecotoxicity combined with a high supply is worrying and it can require interventions to protect the aquatic environment. The retention of the waste can have an adverse effect on microorganisms in reservoirs surface waters or a sludge activity in wastewater treatment plants.

A Summary of In Vitro and In Vivo Studies Evaluating the Impact of E-Cigarette Exposure on Living Organisms and the Environment

Worldwide use of electronic cigarettes has been rapidly expanding over recent years, but the long-term effect of e-cigarette vapor exposure on human health and environment is not well established; however, its mechanism of action entails the production of reactive oxygen species and trace metals, and the exacerbation of inflammation, which are associated with potential cytotoxicity and genotoxicity. The present study examines the effects of selected liquid chemicals used in e-cigarettes, such as propylene glycol/vegetable glycerin, nicotine and flavorings, on living organisms; the data collected indicates that exposure to e-cigarette liquid has potentially detrimental effects on cells in vitro, and on animals and humans in vivo. While e-liquid exposure can adversely influence the physiology of living organisms, vaping is recommended as an alternative for tobacco smoking. The study also compares the impact of e-cigarette liquid exposure and traditional cigarette smoke on organisms and the environmental impact. The environmental influence of e-cigarette use is closely connected with the emission of airborne particulate matter, suggesting the possibility of passive smoking. The obtained data provides an insight into the impact of nicotine delivery systems on living organisms and the environment.

Analysis of Toxic Metals in Liquid from Electronic Cigarettes

As the technology of electronic nicotine delivery systems (ENDS), including e-cigarettes, evolves, assessing metal concentrations in liquids among brands over time becomes challenging. A method for quantification of chromium, nickel, copper, zinc, cadmium, tin, and lead in ENDS liquids using triple quadrupole inductively coupled plasma mass spectrometry was developed. The method’s limits of detection (LODs) were 0.031, 0.032, 3.15, 1.27, 0.108, 0.099, 0.066 µg/g for Cr, Ni, Cu, Zn, Cd, Sn, and Pb respectively. Liquids analyzed were from different brands and flavors of refill bottles or single-use, rechargeable, and pod devices from different years. Scanning electron microscopy with energy dispersive spectroscopy further evaluated the device components’ compositions. Refill liquids before contacting a device were below lowest reportable levels (LRL) for all metals. Copper and zinc were elevated in liquids from devices containing brass. Cadmium was <LRL in all liquids and was not observed in device components. Cr, Ni, Cu, Zn, Sn, and Pb, reported in µg/g, ranged from <LRL to 0.396, 4.04, 903, 454, 0.898, and 13.5 respectively. Elevated metal concentrations in the liquid were also elevated in aerosol from the corresponding device. The data demonstrates the impact of device design and materials on toxic metals in ENDS liquid.

Monoamine oxidase inhibitory activity of flavoured e-cigarette liquids

BACKGROUND AND AIMS

Monoamine oxidase inhibitors have been hypothesised to be important in tobacco dependence, reinforcing the brain's response to nicotine by delaying the degradation of neurotransmitters by monoamine oxidases. The development of electronic cigarettes has provided an alternative nicotine delivery system, which is widely viewed as less toxic than tobacco smoke. However, significant data gaps remain. This paper reports the results of measurements of monoamine oxidase inhibitory activity in a small sample of commercially available, flavoured e-liquids.

METHODS

Twelve e-liquids were tested for monoamine oxidase inhibitory activity, using the kynuramine assay and monoamine oxidase enzymes (human, recombinant). Control samples of carrier liquids, propylene glycol and glycerol, and nicotine were also tested.

RESULTS

Four e-liquids contained high levels of inhibitory activity, four more were moderately inhibitory. The remaining four e-liquids were mildly inhibitory, while the carrier liquids, and nicotine were inactive at relevant concentrations. The active compounds in the e-liquids were subsequently identified as vanillin and ethyl vanillin. Under some conditions of use, the sampled e-liquids with the highest concentrations of monoamine oxidase inhibitory activity have the potential to expose consumers to physiologically significant levels of MAO inhibitory activity.

CONCLUSIONS

While only a small sample of e-liquids was tested, the findings suggest that some flavours have pharmacological actions, with potential to enhance the response to nicotine or to other drugs. The public health implications of these preliminary findings on addiction and smoking cessation warrant exploration and further research.

Nicotine intoxication by e-cigarette liquids: a study of case reports and pathophysiology

Background: Electronic cigarettes (e-cigarettes), the smokeless alternative to conventional tobacco cigarettes, have become increasingly popular. E-cigarettes vaporise e-liquid, a solution of highly concentrated nicotine, propylene glycol (PG) and vegetable glycerine (VG). With the popularity of e-cigarettes, e-liquid refills have become easily accessible and several cases of intoxication due to the ingestion of e-liquid have been reported. We provide an overview of these cases, their pathophysiology and patients' characteristics.Methods: We carried out a retrospective evaluation of the scientific literature reporting on cases of liquid nicotine intoxication, using the following inclusion criteria: (1) the article is or contains a case report, (2) describes an intoxication with e-liquid, (3) the substance contains nicotine, and (4) intake is oral, intravenous or subcutaneous.Results: We found 26 case reports describing a total of 31 patients who suffered from e-liquid intoxication. All intoxications up to the age of six were reported as unintentional, whereas nearly all cases from ages 13 to 53 were due to suicide attempts. The three most prevalent symptoms of e-liquid intoxication were tachycardia, altered mental status and vomiting. Eleven cases resulted in the death of the patient. In the survivors, the highest plasma concentration of nicotine was 800 µg L^-1, while the lowest concentration in the non-survivors was 1600 µg L^-1.Conclusions: There is a mismatch between the generally accepted lethal oral nicotine dose of 60 mg, resulting in approximately 180 µg L^-1 plasma concentration, and the 4.4- to 8.9-fold higher lethal plasma concentrations we found in cases of e-liquid intoxication. In these severe intoxications, plasma cotinine concentration does not act as a more reliable indicator of nicotine intoxication than nicotine itself. The ages of the patients display a bimodal distribution. In patients above the age of 10, intoxication results mainly from suicide attempts rather than accidental ingestion. The role of PG and VG in e-liquid intoxications is remarkably unclear. However, the similarity across nicotine and PG toxicity symptoms leads us to believe a cumulative effect cannot be excluded.

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

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

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.

Radiolabeling an Electronic Cigarette Aerosol Using Technetium Carbon Ultrafine Particles

BACKGROUND

Electronic cigarettes (ECIGs) are widely used, but their health effects are not well known. ECIG exposure is difficult to quantify, and a direct measurement of deposition would be beneficial to in vivo and in vitro toxicity studies. The aim of this study was to demonstrate effective radiolabeling of an ECIG.

METHODS

A technetium-99m-labeled carbon ultrafine (TCU) aerosol was generated and introduced to a fourth-generation ECIG before nucleation and aerosol formation. The aerosolized e-liquid was a commercially available strawberry flavor containing 1.2% nicotine in a 55% propylene glycol and 45% vegetable glycerine base. An ECIG power setting of 100 W was selected. Mass and radioactivity were measured on each stage within a Sierra Cascade Impactor at 14 L/min to verify the labeling technique using the calculated aerodynamic diameters. A strong positive correlation (R² > 0.95) between the percent activity and percent mass deposition on each stage provides a reliable validation of colocation.

RESULTS

Unlabeled ECIG aerosol from the chosen e-liquid produced a mass median aerodynamic diameter (MMAD) of 0.85 μm. An ECIG labeled with TCU produced an aerosol with an activity median aerodynamic diameter of 0.84 μm and an MMAD of 0.84 μm. The relative mass versus radioactivity on each plate was highly correlated (average R² = 0.973, p < 0.001).

CONCLUSION

A TCU radiolabel was generated and shown to associate with the mass of an aerosol produced by a typical commercially available ECIG. Thus, the radioactivity of the deposited aerosol may be used to determine ECIG aerosol deposition for the future in vivo and in vitro dosimetry studies of the third- and fourth-generation ECIGs.

Understanding Users' Vaping Experiences from Social Media: Initial Study Using Sentiment Opinion Summarization Techniques

Background

E-liquid is one of the main components in electronic nicotine delivery systems (ENDS). ENDS review comments could serve as an early warning on use patterns and even function to serve as an indicator of problems or adverse events pertaining to the use of specific e-liquids—much like types of responses tracked by the Food and Drug Administration (FDA) regarding medications.

Objective

This study aimed to understand users’ “vaping” experience using sentiment opinion summarization techniques, which can help characterize how consumers think about specific e-liquids and their characteristics (eg, flavor, throat hit, and vapor production).

Methods

We collected e-liquid reviews on JuiceDB from June 27, 2013 to December 31, 2017 using its public application programming interface. The dataset contains 27,070 reviews for 8058 e-liquid products. Each review is accompanied by an overall rating and a set of 4 aspect ratings of an e-liquid, each on a scale of 1-5: flavor accuracy, throat hit, value, and cloud production. An iterative dichotomiser 3 (ID3)-based influential aspect analysis model was adopted to learn the key elements that impact e-liquid use. Then, fine-grained sentiment analysis was employed to mine opinions on various aspects of vaping experience related to e-liquids.

Results

We found that flavor accuracy and value were the two most important aspects that affected users’ sentiments toward e-liquids. Of reviews in JuiceDB, 67.83% (18,362/27,070) were positive, while 12.67% (3430/27,070) were negative. This indicates that users generally hold positive attitudes toward e-liquids. Among the 9 flavors, fruity and sweet were the two most popular. Great and sweet tastes, reasonable value, and strong throat hit made users satisfied with fruity and sweet flavors, whereas “strange” tastes made users dislike those flavors. Meanwhile, users complained about some e-liquids’ steep or expensive prices, bad quality, and harsh throat hit. There were 2342 fruity e-liquids and 2049 sweet e-liquids. There were 55.81% (1307/2342) and 59.83% (1226/2049) positive sentiments and 13.62% (319/2342) and 12.88% (264/2049) negative sentiments toward fruity e-liquids and sweet e-liquids, respectively. Great flavors and good vapors contributed to positive reviews of fruity and sweet products. However, bad tastes such as “sour” or “bitter” resulted in negative reviews. These findings can help businesses and policy makers to further improve product quality and formulate effective policy.

Conclusions

This study provides an effective mechanism for analyzing users’ ENDS vaping experience based on sentiment opinion summarization techniques. Sentiment opinions on aspect and products can be found using our method, which is of great importance to monitor e-liquid products and improve work efficiency.

Enantiomeric composition of nicotine in tobacco leaf, cigarette, smokeless tobacco, and e-liquid by normal phase high-performance liquid chromatography

Evaluating the source of nicotine in e-liquid is a problem. Tobacco-derived nicotine contains predominantly (S)-(-)-nicotine, whereas tobacco-free nicotine products may not. Thus, we developed a new normal phase high-performance liquid chromatography method to determinate the enantiomeric composition of nicotine in 10 kinds of flue-cured tobacco, 3 kinds of burley, 1 kind of cigar tobacco, 2 kinds of oriental tobacco, 5 kinds of Virginia cigarette, 5 kinds of blend cigarette, 10 kinds of e-liquid, and 4 kinds of smokeless tobacco. The amount of (R)-(+)-nicotine ranged from ~0.02% to ~0.76% of total nicotine. An e-liquid sample had the highest level of (R)-(+)-nicotine. The extraction and purification processes used to obtain commercial (S)-(-)-nicotine from the tobacco do not decrease the amount of (R)-(+)-nicotine in tobacco. So the amount of (R)-(+)-nicotine in samples in our work were the same as tobacco samples.

Can Established Vapers Distinguish Different PG:VG Ratios? A Pilot Study

OBJECTIVES

Using the triangle test, this study explores whether established vapers can distinguish small differences between e-liquid propylene glycol: vegetable glycerin (PG:VG) ratios at fixed levels of nicotine and flavor, in order to examine the extent to which solvent ratios affects sensory experiences.

METHODS

Watermelon flavored e-liquids (16mg/mL nicotine) used for this study differed in the ratio of PG:VG (30:70, 50:50; 70:30). Current vapers were randomized to one of 3 possible study conditions differing by PG:VG ratio. Participants sampled products following the triangle test, which presents 3 blinded products, 2 of which are identical. They were asked to identify and rate the 'odd' product.

RESULTS

Of the 14 participants who completed the study, 34.9% were able to determine the 'odd' product. Ratings on the subjective response scales for the 'odd' product were quite low. Aversion scores differed significantly by correct identification of the 'odd' product (p = .045).

CONCLUSIONS

Established vapers in this study were unable to consistently distinguish PG:VG ratios, even for relatively large differences, and correct identification inconsistently related to subjective effects ratings. These preliminary findings suggest that the PG:VG ratio may not be a salient feature of vaping.

Electronic cigarettes: a systematic review of available studies on health risk assessment

OBJECTIVE

This paper primarily aimed to review articles which specifically quantified the risk of electronic cigarette's (e-cigarette) usage via the health risk assessment (HRA) approach.

METHODS

Systematic literature searches were conducted using PubMed search engine databases. Search terms such as "electronic cigarette", "e-cigarette", "electronic nicotine delivery systems", "electronic cigarette liquid", "electronic cigarette vapors", and "health risk assessment" were used to identify the relevant articles to be included in this review. To enable comparison, hazard quotient (HQ) and lifetime cancer risk (LCR) for the chemicals measured in the selected articles were calculated for three of the articles using the formula: [1] HQ=average daily dose (ADD)/reference dose (RfD) or exposure air concentration (EC)/reference concentration (RfC); [2] LCR=lifetime average daily dose (LADD) × cancer slope factor (CSF) or exposure air concentration (EC) × inhalation unit risk (IUR).

RESULTS

Four articles pertaining to HRA of e-cigarettes were critically reviewed, three of the papers focused on specific chemicals namely nicotine, propylene glycol (PG), glycerol and 1,2-propanediol, while one article evaluated the health risks posed by heavy metals contained in e-cigarettes. The calculated HQs for the chemicals in this review had large variations. HQs of the six chemicals, i.e. nicotine, PG, glycerol, cadmium, ethylene glycol, nickel, aluminum and titanium, were found to have the potential to contribute to non-carcinogenic health risks. None of the LCR calculated had risks exceeding the acceptable limit.

CONCLUSION

There are limited HRA studies and the ones that were available provided inconsistent scientific evidences on the health risk characterization arising from the usage of e-cigarettes. As such, there is a need to perform more studies on HRA of e-cigarettes by using uniformed and comprehensive steps and similar reference threshold levels of exposures.

Electronic cigarettes: One size does not fit all

Electronic cigarettes (ECs) have been growing rapidly in popularity among youth and adults in the United States over the last decade. This increasing prevalence is driven partially by the ability to customize devices, flavors, and nicotine content and the general notion that ECs are harmless, particularly in comparison with conventional cigarettes. In vitro and in vivo murine models have demonstrated a number of harmful biological effects of e-liquids and their aerosols. However, limited clinical data exist on whether these effects translate into detrimental long-term outcomes in human subjects. The short-term harmful respiratory effects of EC use demonstrated in nonsmokers argue against their use. However, slightly more favorable data exist for the respiratory benefits of substituting conventional cigarettes with ECs and the short-term efficacy of ECs as smoking cessation tools. Nonetheless, available research is severely limited in regard to long-term outcomes and by study designs fraught with bias, pointing to the need for additional research efforts with well-designed longitudinal studies to guide US Food and Drug Administration regulatory efforts. The hurdle presented by diverse device designs and e-liquid permutations, which contribute to the inconsistency of available data, also highlights the need for legislative standardization of ECs.

Vaping Topography and Reasons of Use among Adults in Klang Valley, Malaysia

Background:

Consistency and accuracy of results in assessing health risks due to vaping or e-cigarette use are difficult to achieve without established consumption data. The present report covers baseline data on vaping topography and reasons for use among local users in Klang Valley, Malaysia.

Methods:

An 80-item survey regarding socio-demographic characteristics, smoking topography and reasons for e-cigarette use was employed to assess e-cigarette users recruited from several public universities and private organisations. The survey questionnaire was self-administered. Data were analysed using statistical software.

Results:

Eighty-six current e-cigarette users participated with more than half (51.2%) of them aged ≥ 25 years old. Significant proportions of the sample were single (51.2%), had a tertiary education level (63.5%) and a household income of less than USD1000 per month (65.2%). Median duration of e-cigarette use was less than a year; users drew approximately 50 puffs per day and refilled twice a day. The majority (74%) used e-liquids containing nicotine with a concentration of 6 μg/mL. Daily users spent USD18-23 per month. Reasons for using the e-cigarette included enjoyment of the products (85.9%), perception of lower toxicity than tobacco (87%), and the fact that it was a cheaper smoking alternative (61%).

Conclusion:

The data on e-cigarette smoking topography obtained in this study are novel. The reasons of usage were mainly users’ enjoyment of e-cigarettes, preparation for quitting smoking, perception of low toxicity and a healthier smoking substitute and cheapness in the long run. The results establish basic knowledge for the local vaping topography and reference material for future e-cigarette-related research.

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.

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.