Carbonyl Emissions in E-cigarette Aerosol: A Systematic Review and Methodological Considerations

Carbonyl emissions from tobacco cigarettes represent a substantial health risk contributing to smoking-related morbidity and mortality. As expected, this is an important research topic for tobacco harm reduction products, in an attempt to compare the relative risk of these products compared to tobacco cigarettes. In this study, a systematic review of the literature available on PubMed was performed analyzing the studies evaluating carbonyl emissions from e-cigarettes. A total of 32 studies were identified and presented. We identified a large diversity of methodologies, with substantial discrepancies in puffing patterns, aerosol collection and analytical methods as well as reported units of measurements. Such discrepancies make comparisons difficult, and in some cases the accuracy of the findings cannot be determined. Importantly, control for the generation of dry puffs was not performed in the vast majority of studies, particularly in studies using variable power devices, which could result in testing conditions and reported carbonyl levels that have no clinical relevance or context. Some studies have been replicated, verifying the presence of dry puff conditions. Whenever realistic use conditions were ensured, carbonyl emissions from e-cigarettes were substantially lower than tobacco cigarette smoke, while newer generation (bottom-coil, cotton wick) atomizers appeared to emit minimal levels of carbonyls with questionable clinical significance in terms of health risk. However, extremely high levels of carbonyl emissions were reported in some studies, and all these studies need to be replicated because of potentially important health implications

Acute vs. chronic effects of e-cigarettes on vascular function

This commentary refers to `Short-term e-cigarette vapour exposure causes vascular oxidative stress and dysfunction: evidence for a close connection to brain damage and a key role of the phagocytic NADPH oxidase (NOX-2)', by M. Kuntic et al., doi: 10.1093/eurheartj/ehz772

E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys

Introduction: The purpose of this study was to examine the association between electronic cigarette (e-cigarette) use and smoking cessation among US adults. Duration of smoking cessation was taken into consideration because e-cigarette awareness and use were low in the United States before 2010. Methods: A pooled analysis of the 2016 and 2017 National Health Interview Surveys on current (N = 9935) and former smokers (N = 14 754) was performed. Adjusted prevalence ratios (aPRs), for sociodemographic factors, were calculated. Findings: Current e-cigarette use was reported by 10.5% (95% CI = 9.8% to 11.3%) of current smokers and 4.5% (95% CI = 4.0% to 5.0%) of former smokers. Prevalence was high in former smokers of less than 1 year (16.8%, 95% CI = 13.9% to 20.2%), 1-3 years (15.0%, 95% CI = 13.0% to 17.3%), and 4-6 years (10.5%, 95% CI = 8.6% to 12.7%), and very low in former smokers of more than 6 years (0.7%, 95% CI = 0.5% to 0.9%). Similar patterns were observed for daily e-cigarette use. Current e-cigarette use was negatively associated with being a former smoker when quit duration was ignored (aPR = 0.64, 95% CI = 0.59 to 0.69) but was positively associated with being a former smoker of less than 1 year (aPR = 1.44, 95% CI = 1.12 to 1.84) and 1-3 years (aPR = 1.21, 95% CI = 1.03 to 1.42). Daily e-cigarette use was not associated with being a former smoker when quit duration was ignored but was positively associated with being a former smoker of less than 1 year (aPR = 3.44, 95% CI = 2.63 to 4.49), 1-3 years (aPR = 2.51, 95% CI = 2.13 to 2.95), and 4-6 years (aPR = 1.84, 95% CI = 1.49 to 2.26). Conclusions: Daily e-cigarette use is strongly associated with recent smoking cessation (<= 6 years) among US adults. Frequency of e-cigarette use and smoking cessation duration are important parameters when analyzing the effects of e-cigarettes in population surveys

Are Metals Emitted from Electronic Cigarettes a Reason for Health Concern? A Risk-Assessment Analysis of Currently Available Literature

Background: Studies have found that metals are emitted to the electronic cigarette (EC) aerosol. However, the potential health impact of exposure to such metals has not been adequately defined. The purpose of this study was to perform a risk assessment analysis, evaluating the exposure of electronic cigarette (EC) users to metal emissions based on findings from the published literature. Methods: Two studies were found in the literature, measuring metals emitted to the aerosol from 13 EC products. We estimated that users take on average 600 EC puffs per day, but we evaluated the daily exposure from 1200 puffs. Estimates of exposure were compared with the chronic Permissible Daily Exposure (PDE) from inhalational medications defined by the U.S. Pharmacopeia (cadmium, chromium, copper, lead and nickel), the Minimal Risk Level (MRL) defined by the Agency for Toxic Substances and Disease Registry (manganese) and the Recommended Exposure Limit (REL) defined by the National Institute of Occupational Safety and Health (aluminum, barium, iron, tin, titanium, zinc and zirconium). Results: The average daily exposure from 13 EC products was 2.6 to 387 times lower than the safety cut-off point of PDEs, 325 times lower than the safety limit of MRL and 665 to 77,514 times lower than the safety cut-off point of RELs. Only one of the 13 products was found to result in exposure 10% higher than PDE for one metal (cadmium) at the extreme daily use of 1200 puffs. Significant differences in emissions between products were observed. Conclusions: Based on currently available data, overall exposure to metals from EC use is not expected to be of significant health concern for smokers switching to EC use, but is an unnecessary source of exposure for never-smokers. Metal analysis should be expanded to more products and exposure can be further reduced through improvements in product quality and appropriate choice of materials

Harmful effects from one puff of shisha-pen vapor: methodological and interpretational problems in the risk assessment analysis

With this letter we express our concerns about the applicability of the proposed Margin of Exposure analysis as a method of risk assessment for propylene glycol and glycerol exposure from a shisha-pen type electronic cigarette. The studies used to determine the Margin of Exposure were evaluating the effects in humans or animals of continuous exposure to these chemicals in every single breath, whereas electronic cigarettes are used intermittently by consumers, resulting in lower and discontinuous exposure. Moreover, the authors make no clear distinction between irritation and harm, neither do they discuss the effects of exposure compared to continuous smoking.status: publishe

Chronic Idiopathic Neutrophilia in A Smoker, Relieved after Smoking Cessation with the Use of Electronic Cigarette: a Case Report

Introduction Smoking is a major risk factor for a variety of diseases. Electronic cigarettes are battery-operated devices that deliver nicotine to the lungs by evaporation of a liquid. Chronic idiopathic neutrophilia is a condition characterized by elevated white blood cell and neutrophil counts without any underlying disease; smoking has been implicated as a potential cause. Case Presentation A male Caucasian patient, born in 1977, presented in September 2005 with asymptomatic elevation of white blood cell and neutrophil count, and mildly-elevated C-reactive protein levels. He was a smoker since 1996 and was treated with 20 mg/day of simvastatin since 2003 due to hyperlipidemia. Clinical examination, and laboratory and imaging investigations ruled out any infectious, haematological, rheumatological, or endocrine conditions. He was followed-up regularly and was advised to stop smoking. He had 2 unsuccessful attempts to quit smoking; one was unassisted and the second was performed with the use of both varenicline and nicotine replacement therapy (patches). During the subsequent 6.5 years, his leukocyte and C-reactive protein levels were repeatedly elevated; the condition was consistent with chronic idiopathic neutrophilia. In February 2012, he started using electronic cigarettes and he managed to quit smoking within 10 days. After 6 months, laboratory examination showed normalized leukocyte count and C-reactive protein levels, confirmed immediately by a second laboratory and by repeated tests after 1 and 2 months. Conclusion Smoking cessation with the use of electronic cigarette led to reversal of chronic idiopathic neutrophilia. The daily use of electronic cigarette may help preserve the beneficial effects of smoking cessation

Association between electronic cigarette use and smoking cessation in the European Union in 2017: analysis of a representative sample of 13 057 Europeans from 28 countries

Objectives To examine the association between electronic cigarette (e-cigarette) use and smoking cessation in the European Union (EU) in 2017 according to e-cigarette use frequency and smoking cessation duration. Design Cross-sectional survey of EU citizens, representative of the population (Special Eurobarometer 458). Weighted proportions (95% CI) and adjusted prevalence ratios (aPRs) were calculated. Setting EU. Participants 13 057 EU citizens aged >= 15 years (6904 current and 6153 former smokers). Results Current daily e-cigarette use was reported by 2.4% (1.8%-3.1%) of current and 3.3% (2.5%-4.2%) of former smokers (p=0.002), while former daily use was reported by 5.6% (4.7%-6.8%) and 1.9% (1.3%-2.7%), respectively (p<0.001). More than half of all former smokers had quit for >10 years. Current daily e-cigarette use was rare among former smokers of >10 years (0.2%, 0.1%-0.6%) and was more prevalent in former smokers of <= 2 and 3-5 years (12.9%, 9.1%-17.9% and 9.0%, 5.8%-13.7%, respectively). Compared with never use, current daily e-cigarette use was associated with being a former smoker of <= 2 (aPR 4.96, 95% CI 3.57 to 6.90) and 3-5 years (aPR 3.20, 95% CI 2.10 to 4.87). Former daily e-cigarette use was associated with being a former smoker of <= 2 years (aPR 1.96, 95% CI 1.21 to 3.12). Current daily e-cigarette use was negatively associated with being a former smoker of 5-10 and >10 years. Conclusions Current daily e-cigarette use in the EU in 2017 was rare among former smokers of >10 years and was positively associated with recent (<= 5 years) smoking cessation. Former daily e-cigarette use was also positively associated with recent (<= 2 years) smoking cessation

Do flavouring compounds contribute to aldehyde emissions in e-cigarettes?

Introduction A recent study identified up to 10,000-fold higher aldehyde emissions from flavoured compared to unflavoured e-cigarette liquids. We set to replicate this study and also test similar flavourings with a new-generation e-cigarette device. Methods: Three liquids with the highest levels of aldehyde emissions in the previous study were tested (in standard and sweetened versions) using the same e-cigarette device and puffing patterns. Additionally, similar flavourings from a different manufacturer were tested using a new-generation e-cigarette device. Unflavoured samples were also tested. Results: Low levels of formaldehyde (8.3-62 mu g/g), acetaldehyde (12.1-26.0 mu g/g) and acrolein (5.4-19.4 mu g/g) were detected, lower by up to 589-fold compared to the previous report. Unflavoured liquid emitted 16.1 mu g/g formaldehyde, 5.6 mu g/g acetaldehyde and 2.4 mu g/g acrolein, significantly lower compared to 2 liquids for formaldehyde and 1 for acrolein. Emissions from the new-generation device were even lower. Aldehyde emissions from all flavoured liquids were 79-99.8% lower than smoking and lower than commonly measured indoor levels and occupational and indoor safety limits. Conclusions: The e-cigarettes tested herein emit very low levels of aldehydes. Some flavourings may contribute to aldehyde emissions, but the absolute levels were minimal. Validated methods should be used when analysing e-cigarette emissions

Metal emissions from e-cigarettes: a risk assessment analysis of a recently-published study

Introduction: A recent study reported levels of metal emissions in e-cigarette (EC) aerosol. Herein we present a risk assessment analysis of the published findings using total daily exposure limits.Methods: Median and 75th percentile metal concentrations in EC aerosols were used to determine the level of daily liquid consumption (g/d) that would exceed the permissible daily exposures (PDEs) defined for inhalation medications (cadmium, chromium, copper, nickel, lead, antimony and tin). For metals not having PDEs, minimal risk levels (manganese) or risk exposure levels (aluminum, iron and zinc) were converted into total daily exposure using an inhalation volume of 20m(3) (for 24h) and 6.7m(3) (for 8h) respectively.Results: The lowest amount of liquid consumption exceeding safety limits was found for nickel (73g/day for median and 17g/day for 75th percentile levels). The consumption corresponding to the 75th percentile could be associated with realistic use, although this would represent an extreme rather than average consumption. For chromium, the respective levels were 358 and 68g/day and for lead 338 and 135g/day. For all other metals, liquid consumption would need to be orders of magnitude higher, reaching to 1.5 million grams for aluminum.Conclusion: EC emissions contain trace levels of metals. For almost all metals, unrealistically high levels of liquid need to be consumed in order for total daily exposure to exceed established limits