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.

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. IMPLICATIONS: There is controversy on whether e-cigarettes promote or prevent smoking cessation. This study presents a detailed analysis of the association between e-cigarette use and smoking cessation in the United States considering frequency of e-cigarette use and duration of smoking cessation. The latter was considered appropriate because e-cigarette awareness and use were low in the United States before 2010. Daily e-cigarette use is strongly associated with recent (≤6 years) smoking cessation in the United States. Both frequency of e-cigarette use and duration of smoking cessation are important factors in determining the effects of e-cigarettes in population studies.

Nicotine Delivery to the Aerosol of a Heat-Not-Burn Tobacco Product: Comparison With a Tobacco Cigarette and E-Cigarettes.

Introduction: The purpose was to measure nicotine levels to the tobacco and levels emitted to the aerosol of a heat-not-burn product (HnB, IQOS) compared to e-cigarettes (ECs) and a tobacco cigarette. Methods: The HnB device and regular and menthol sticks were purchased from Italy. Three types of ECs (ciga-like, eGo-style, and variable wattage) and a commercially-available tobacco cigarette were also tested. A custom-made liquid containing 2% nicotine was used with ECs. Products were tested using Health Canada Intense puffing regime while HnB and ECs were additionally tested using a 4-second puff duration regime while maintaining the same puff volume. Results: Nicotine content in HnB regular and menthol tobacco sticks was 15.2 ± 1.1 mg/g and 15.6 ± 1.7 mg/g tobacco respectively. The levels of nicotine to the aerosol were similar for regular and menthol HnB products (1.40 ± 0.16 and 1.38 ± 0.11 mg/12 puffs respectively) and did not change significantly with prolonged puff duration. The tobacco cigarette delivered the highest level of nicotine (1.99 ± 0.20 mg/cigarette), with levels being higher than HnB and ECs under Health Canada Intense regime but similar to eGo-style and variable wattage ECs at prolonged puff duration regime. Conclusions: The HnB product delivers nicotine to the aerosol at levels higher than ECs but lower than a tobacco cigarette when tested using Health Canada Intense puffing regime. No change in HnB nicotine delivery was observed at prolonged puff duration with the same puff volume, unlike ECs which deliver more nicotine with longer puff duration. Implications: Nicotine delivery to the smoker is expected to play an important role in the ability of any harm-reduction product to successfully substitute smoking. This study evaluated the content and nicotine delivery to the aerosol of a heat-not-burn tobacco product (IQOS) in comparison with e-cigarettes and a tobacco cigarette. The main findings were that the heat-not-burn tobacco sticks contained similar nicotine concentration to tobacco cigarettes, and that the levels of nicotine delivered to the aerosol of the heat-not-burn products were lower than tobacco cigarette, higher than e-cigarettes at low puff duration but lower than high-power e-cigarettes at longer puff duration.

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 20 m3 (for 24 h) and 6.7 m3 (for 8 h) respectively. Results: The lowest amount of liquid consumption exceeding safety limits was found for nickel (73 g/day for median and 17 g/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 68 g/day and for lead 338 and 135 g/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.

Electronic cigarette use in Greece: an analysis of a representative population sample in Attica prefecture.

BACKGROUND: The purpose was to assess prevalence and correlates of electronic cigarette (e-cigarette) use in Greece in 2017. METHODS: A cross-sectional survey of a representative sample of 4058 adults living in Attica prefecture (35% of the Greek adult population) was performed in May 2017 through telephone interviews. Prevalence and frequency of e-cigarette use were assessed according to the smoking status, and logistic regression analysis was performed to identify correlates of use. RESULTS: Current smoking was reported by 32.6% of participants. Ever e-cigarette use was reported by 54.1% (51.4-56.8%) of current smokers, 24.1% (21.7-26.5%) of former smokers and 6.5% (5.3-7.7%) of never smokers. Past experimentation was the most prevalent pattern of e-cigarette use among ever users (P < 0.001). Almost 80% of ever and 90% of current e-cigarette users were using nicotine. Extrapolated to the whole Attica population (3.1 million), there were 1 million current smokers, 848,000 ever e-cigarette users and 155,000 current e-cigarette users. The majority of current e-cigarette users (62.2%) were former smokers. Only 0.2% of never smokers were current e-cigarette users. One out of 20 participants considered e-cigarettes a lot less harmful than smoking. Being current or former smoker were the strongest correlates current e-cigarette use (OR 30.82, 95%CI 10. 21-69.33 and OR 69.33, 95%CI 23.12-207.90 respectively). CONCLUSIONS: E-cigarette use in Greece is largely confined to current or former smokers, while current use and nicotine use by never smokers is extremely rare. The majority of current e-cigarette users were former smokers. Most participants overestimate the harmfulness of e-cigarettes relative to smoking.

A critique of the US Surgeon General's conclusions regarding e-cigarette use among youth and young adults in the United States of America.

BACKGROUND: In December 2016, the Surgeon General published a report that concluded e-cigarette use among youth and young adults is becoming a major public health concern in the United States of America. METHODS: Re-analysis of key data sources on nicotine toxicity and prevalence of youth use of e-cigarettes cited in the Surgeon General report as the basis for its conclusions. RESULTS: Multiple years of nationally representative surveys indicate the majority of e-cigarette use among US youth is either infrequent or experimental, and negligible among never-smoking youth. The majority of the very small proportion of US youth who use e-cigarettes on a regular basis, consume nicotine-free products. The sharpest declines in US youth smoking rates have occurred as e-cigarettes have become increasingly available. Most of the evidence presented in the Surgeon General's discussion of nicotine harm is not applicable to e-cigarette use, because it relies almost exclusively on exposure to nicotine in the cigarette smoke and not to nicotine present in e-cigarette aerosol emissions. Moreover, the referenced literature describes effects in adults, not youth, and in animal models that have little relevance to real-world e-cigarette use by youth. The Surgeon General's report is an excellent reference document for the adverse outcomes due to nicotine in combination with several other toxicants present in tobacco smoke, but fails to address the risks of nicotine decoupled from tobacco smoke constituents. The report exaggerates the toxicity of propylene glycol (PG) and vegetable glycerin (VG) by focusing on experimental conditions that do not reflect use in the real-world and provides little discussion of emerging evidence that e-cigarettes may significantly reduce harm to smokers who have completely switched. CONCLUSIONS: The U.S. Surgeon General's claim that e-cigarette use among U.S. youth and young adults is an emerging public health concern does not appear to be supported by the best available evidence on the health risks of nicotine use and population survey data on prevalence of frequent e-cigarette use. Nonetheless, patterns of e-cigarettes use in youth must be constantly monitored for early detection of significant changes. The next US Surgeon General should consider the possibility that future generations of young Americans will be less likely to start smoking tobacco because of, not in spite of, the availability of e-cigarettes.

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

INTRODUCTION: The purpose of this study was to evaluate sweet-flavored electronic cigarette (EC) liquids for the presence of diacetyl (DA) and acetyl propionyl (AP), which are chemicals approved for food use but are associated with respiratory disease when inhaled. METHODS: In total, 159 samples were purchased from 36 manufacturers and retailers in 7 countries. Additionally, 3 liquids were prepared by dissolving a concentrated flavor sample of known DA and AP levels at 5%, 10%, and 20% concentration in a mixture of propylene glycol and glycerol. Aerosol produced by an EC was analyzed to determine the concentration of DA and AP. RESULTS: DA and AP were found in 74.2% of the samples, with more samples containing DA. Similar concentrations were found in liquid and aerosol for both chemicals. The median daily exposure levels were 56 µg/day (IQR: 26-278 µg/day) for DA and 91 µg/day (IQR: 20-432 µg/day) for AP. They were slightly lower than the strict NIOSH-defined safety limits for occupational exposure and 100 and 10 times lower compared with smoking respectively; however, 47.3% of DA and 41.5% of AP-containing samples exposed consumers to levels higher than the safety limits. CONCLUSIONS: DA and AP were found in a large proportion of sweet-flavored EC liquids, with many of them exposing users to higher than safety levels. Their presence in EC liquids represents an avoidable risk. Proper measures should be taken by EC liquid manufacturers and flavoring suppliers to eliminate these hazards from the products without necessarily limiting the availability of sweet flavors.

Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes.

BACKGROUND: Electronic cigarettes have been developed and marketed in recent years as smoking substitutes. However, no studies have evaluated their effects on the cardiovascular system. The purpose of this study was to examine the immediate effects of electronic cigarette use on left ventricular (LV) function, compared to the well-documented acute adverse effects of smoking. METHODS: Echocardiographic examinations were performed in 36 healthy heavy smokers (SM, age 36 ± 5 years) before and after smoking 1 cigarette and in 40 electronic cigarette users (ECIG, age 35 ± 5 years) before and after using the device with "medium-strength" nicotine concentration (11 mg/ml) for 7 minutes. Mitral flow diastolic velocities (E, A), their ratio (E/A), deceleration time (DT), isovolumetric relaxation time (IVRT) and corrected-to-heart rate IVRT (IVRTc) were measured. Mitral annulus systolic (Sm), and diastolic (Em, Am) velocities were estimated. Myocardial performance index was calculated from Doppler flow (MPI) and tissue Doppler (MPIt). Longitudinal deformation measurements of global strain (GS), systolic (SRs) and diastolic (SRe, SRa) strain rate were also performed. RESULTS: Baseline measurements were similar in both groups. In SM, IVRT and IVRTc were prolonged, Em and SRe were decreased, and both MPI and MPIt were elevated after smoking. In ECIG, no differences were observed after device use. Comparing after-use measurements, ECIG had higher Em (P = 0.032) and SRe (P = 0.022), and lower IVRTc (P = 0.011), MPI (P = 0.001) and MPIt (P = 0.019). The observed differences were significant even after adjusting for changes in heart rate and blood pressure. CONCLUSIONS: Although acute smoking causes a delay in myocardial relaxation, electronic cigarette use has no immediate effects. Electronic cigarettes' role in tobacco harm reduction should be studied intensively in order to determine whether switching to electronic cigarette use may have long-term beneficial effects on smokers' health. TRIAL REGISTRATION: Current Controlled Trials ISRCTN16974547.

Cytotoxicity evaluation of electronic cigarette vapor extract on cultured mammalian fibroblasts (ClearStream-LIFE): comparison with tobacco cigarette smoke extract.

CONTEXT: Electronic cigarettes (ECs) are used as alternatives to smoking; however, data on their cytotoxic potential are scarce. OBJECTIVE: To evaluate the cytotoxic potential of 21 EC liquids compared to the effects of cigarette smoke (CS). METHODS: Cytotoxicity was evaluated according to UNI EN ISO 10993-5 standard. By activating an EC device, 200 mg of liquid was evaporated and was extracted in 20 ml of culture medium. CS extract from one cigarette was also produced. The extracts, undiluted (100%) and in five dilutions (50%, 25%, 12.5%, 6.25% and 3.125%), were applied to cultured murine fibroblasts (3T3), and viability was measured after 24-hour incubation by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Viability of less than 70% was considered cytotoxic. RESULTS: CS extract showed cytotoxic effects at extract concentrations above 12.5% (viability: 89.1 ± 3.5% at 3.125%, 77.8 ± 1.8% at 6.25%, 72.8 ± 9.7% at 12.5%, 5.9 ± 0.9% at 25%, 9.4 ± 5.3% at 50% and 5.7 ± 0.7% at 100% extract concentration). Range of fibroblast viability for EC vapor extracts was 88.5-117.8% at 3.125%, 86.4-115.3% at 6.25%, 85.8-111.7% at 12.5%, 78.1-106.2% at 25%, 79.0-103.7% at 50% and 51.0-102.2% at 100% extract concentration. One vapor extract was cytotoxic at 100% extract concentration only (viability: 51.0 ± 2.6%). However, even for that liquid, viability was 795% higher relative to CS extract. CONCLUSIONS: This study indicates that EC vapor is significantly less cytotoxic compared tobacco CS. These results should be validated by clinical studies.

Is e-cigarette use associated with coronary heart disease and myocardial infarction? Insights from the 2016 and 2017 National Health Interview Surveys.

BACKGROUND: This study analyzed the National Health Interview Surveys (NHIS) of 2016 (n = 33,028) and 2017 (n = 26,742) to examine whether e-cigarette use is consistently associated with myocardial infarction (MI) and coronary heart disease (CHD). METHODS: Surveys were examined separately and pooled. Logistic regression analysis was used, with demographics, e-cigarette use, smoking and risk factors for CHD (hypertension, hypercholesterolemia, and diabetes) being independent variables. Former smokers were subclassified according to quit duration (⩽ 6 and > 6 years). RESULTS: For MI, an association was observed with some days e-cigarette (but not daily) use in the 2017 survey (OR: 2.11, 95% CI: 1.14-3.88, p = 0.017). No statistically significant association was observed in the pooled analysis (daily e-cigarette use: OR: 1.35, 95% CI: 0.80-2.27, p = 0.267). For CHD, an association was observed with daily e-cigarette use in the 2016 survey (OR: 1.89, 95% CI: 1.01-3.53, p = 0.047). From the pooled analysis, no association was found between any pattern of e-cigarette use and CHD. In single-year and pooled analysis, both MI and CHD were strongly associated with all patterns of smoking, hypertension, hypercholesterolemia, diabetes, and age. CONCLUSIONS: The pooled analysis of the 2016 and 2017 NHIS showed no association between e-cigarette use and MI or CHD. The associations between established risk factors, including smoking, and both conditions were remarkably consistent. The inconsistent associations observed in single-year surveys and the cross-sectional design of the NHIS cannot substantiate any link between e-cigarette use and an elevated risk for MI or CHD. Longitudinal studies are needed to explore the effects of e-cigarette use on cardiovascular disease.

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 µg/g), acetaldehyde (12.1-26.0 µg/g) and acrolein (5.4-19.4 µg/g) were detected, lower by up to 589-fold compared to the previous report. Unflavoured liquid emitted 16.1 µg/g formaldehyde, 5.6 µg/g acetaldehyde and 2.4 µg/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.

Aldehyde levels in e-cigarette aerosol: Findings from a replication study and from use of a new-generation device.

PURPOSE: A recent study identified high aldehyde emissions from e-cigarettes (ECs), that when converted to reasonable daily human EC liquid consumption, 5 g/day, gave formaldehyde exposure equivalent to 604-3257 tobacco cigarettes. We replicated this study and also tested a new-generation atomizer under verified realistic (no dry puff) conditions. DESIGN: CE4v2 atomizers were tested at 3.8 V and 4.8 V, and a Nautilus Mini atomizer was tested at 9.0 W and 13.5 W. All measurements were performed in a laboratory ISO-accredited for EC aerosol collection and aldehyde measurements. RESULTS: CE4v2 generated dry puffs at both voltage settings. Formaldehyde levels were >10-fold lower, acetaldehyde 6-9-fold lower and acrolein 16-26-fold lower than reported in the previous study. Nautilus Mini did not generate dry puffs, and minimal aldehydes were emitted despite >100% higher aerosol production per puff compared to CE4v2 (formaldehyde: 16.7 and 16.5 µg/g; acetaldehyde: 9.6 and 10.3 µg/g; acrolein: 8.6 and 11.7 µg/g at 9.0 W and 13.5 W, respectively). EC liquid consumption of 5 g/day reduces aldehyde exposure by 94.4-99.8% compared to smoking 20 tobacco cigarettes. CONCLUSION: Checking for dry puffs is essential for EC emission testing. Under realistic conditions, new-generation ECs emit minimal aldehydes/g liquid at both low and high power. Validated methods should be used when analyzing EC aerosol.

Carbonyl emissions from a novel heated tobacco product (IQOS): comparison with an e-cigarette and a tobacco cigarette.

AIMS: To measure carbonyl emissions from a heated tobacco product (IQOS) in comparison with an e-cigarette (Nautilus Mini) and a commercial tobacco cigarette (Marlboro Red). DESIGN: Regular and menthol variants of the heated tobacco product were tested. A tank-type atomizer was tested with a tobacco-flavoured liquid at 10 and 14 W. Aerosol and smoke were collected in impingers containing 2,4-dinitrophenylhydrazine. Health Canada Intense and two more intense puffing regimens were used. SETTING: Analytical laboratory in Greece. MEASUREMENTS: Carbonyl levels in the aerosol and smoke. FINDINGS: At the Health Canada Intense regimen, heated tobacco products emitted 5.0-6.4 µg/stick formaldehyde, 144.1-176.7 µg/stick acetaldehyde, 10.4-10.8 µg/stick acrolein, 11.0-12.8 µg/stick propionaldehyde and 1.9-2.0 µg/stick crotonaldehyde. Compared with the tobacco cigarette, levels were on average 91.6% lower for formaldehyde, 84.9% lower for acetaldehyde, 90.6% lower for acrolein, 89.0% lower for propionaldehyde and 95.3% lower for crotonaldehyde. The e-cigarette emitted 0.5-1.0 µg/12 puffs formaldehyde, 0.8-1.5 µg/12 puffs acetaldehyde and 0.3-0.4 µg/12 puffs acrolein, but no propionaldehyde and crotonaldehyde. At more intense puffing regimens, formaldehyde was increased in heated tobacco products, but levels were three-fourfold lower compared with the tobacco cigarette. Based on the findings from Health Canada Intense puffing regimen, use of 20 heated tobacco sticks would result in approximately 85% to 95% reduced carbonyl exposure compared with smoking 20 tobacco cigarettes; the respective reduction in exposure from use of 5 g e-cigarette liquid would be 97% to > 99%. CONCLUSIONS: The IQOS heated tobacco product emits substantially lower levels of carbonyls than a commercial tobacco cigarette (Marlboro Red) but higher levels than a Nautilus Mini e-cigarette.

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.

E-cigarettes emit very high formaldehyde levels only in conditions that are aversive to users: A replication study under verified realistic use conditions.

PURPOSE: In 2015, a study identified 5-15-fold higher levels of formaldehyde emissions from an old-generation e-cigarette tested at 5.0 V compared to tobacco cigarettes. We set to replicate this study using the same e-cigarette equipment and e-liquid, while checking for the generation of dry puffs. DESIGN: Experienced e-cigarette users (n = 26) took 4 s puffs at different voltage settings and were asked to report the generation of dry puffs. Formaldehyde emissions were measured at both realistic and dry puff conditions. RESULTS: Dry puffs were detected at ≤4.2 V by 88% of participants; thus, 4.0 V was defined as the upper limit of realistic use. Levels ranged from 3.4 (SE = 2.2) µg/10 puffs at 3.3 V to 718.2 (SE = 58.2) µg/10 puffs at 5.0 V. The levels detected at 4.0 V were 19.8 (SE = 5.6) µg/10 puffs. At 4.0 V, the daily exposure to formaldehyde from consuming 3 g of liquid with the device tested would be 32% lower compared to smoking 20 tobacco cigarettes. CONCLUSIONS: The high levels of formaldehyde emissions that were reported in a previous study were caused by unrealistic use conditions that create the unpleasant taste of dry puffs to e-cigarette users and are thus avoided.