Evaluation of Electronic Cigarette Use (Vaping) Topography and Estimation of Liquid Consumption: Implications for Research Protocol Standards Definition and for Public Health Authorities’ Regulation

Abstract

Background: Although millions of people are using electronic cigarettes (ECs) and research on this topic has intensified in recent years, the pattern of EC use has not been systematically studied. Additionally, no comparative measure of exposure and nicotine delivery between EC and tobacco cigarette or nicotine replacement therapy (NRTs) has been established. This is important, especially in the context of the proposal for a new Tobacco Product Directive issued by the European Commission. Methods: A second generation EC device, consisting of a higher capacity battery and tank atomiser design compared to smaller cigarette-like batteries and cartomizers, and a 9 mg/mL nicotine-concentration liquid were used in this study. Eighty subjects were recruited; 45 experienced EC users and 35 smokers. EC users were video-recorded when using the device (ECIG group), while smokers were recorded when smoking (SM-S group) and when using the EC (SM-E group) in a randomized cross-over design. Puff, inhalation and exhalation duration were measured. Additionally, the amount of EC liquid consumed by experienced EC users was measured at 5 min (similar to the time needed to smoke one tobacco cigarette) and at 20 min (similar to the time needed for a nicotine inhaler to deliver 4 mg nicotine). Results: Puff duration was significantly higher in ECIG (4.2 ± 0.7 s) compared to SM-S (2.1 ± 0.4 s) and SM-E (2.3 ± 0.5 s), while inhalation time was lower (1.3 ± 0.4, 2.1 ± 0.4 and 2.1 ± 0.4 respectively). No difference was observed in exhalation duration. EC users took 13 puffs and consumed 62 ± 16 mg liquid in 5 min; they took 43 puffs and consumed 219 ± 56 mg liquid in 20 min. Nicotine delivery was estimated at 0.46 ± 0.12 mg after 5 min and 1.63 ± 0.41 mg after 20 min of use. Therefore, 20.8 mg/mL and 23.8 mg/mL nicotine-containing liquids would deliver 1 mg of nicotine in 5 min and 4 mg nicotine in 20 min, respectively. Since the ISO method significantly underestimates nicotine delivery by tobacco cigarettes, it seems that liquids with even higher than 24 mg/mL nicotine concentration would be comparable to one tobacco cigarette. Conclusions: EC use topography is significantly different compared to smoking. Four-second puffs with 20–30 s interpuff interval should be used when assessing EC effects in laboratory experiments, provided that the equipment used does not get overheated. Based on the characteristics of the device used in this study, a 20 mg/mL nicotine concentration liquid would be needed in order to deliver nicotine at amounts similar to the maximum allowable content of one tobacco cigarette (as measured by the ISO 3308 method). The results of this study do not support the statement of the European Commission Tobacco Product Directive that liquids with nicotine concentration of 4 mg/mL are comparable to NRTs in the amount of nicotine delivered to the user.

Short‐Term E‐Cigarette Exposure Increases the Risk of Thrombogenesis and Enhances Platelet Function in Mice

“…A 15‐minute break between the 2 exposure sessions was given so that the animals could access fresh air, food, and water. The puff duration was 3 seconds, puff interval 1 minute, and the puff volume was 50 mL, all of which mimics real‐life exposure scenarios 24, 25, 26, 27, 28, 29, 30, 31, 32, 33. As for the controls or control mice, they were matched in terms of age and sex (ie, 10‐week‐old males), and were exposed to clean air.…”

First‐ versus second‐generation electronic cigarettes: predictors of choice and effects on urge to smoke and withdrawal symptoms

“…Participants were instructed to take ten puffs each of three-second duration with a thirtysecond inter-puff interval (IPI). The original intention was to use a longer four second puff duration 8 (as recommended by [30]), however, during a pilot study it became evident that the four-second puff duration was too long for the cigalike device, producing over-heating and coughing. Consequently, puff length was reduced to three seconds for both conditions.…”

Risks of Attempting to Regulate Nicotine Flux in Electronic Cigarettes

“…Surveys of dedicated EC users (which were all former smokers) have shown that high nicotine levels are important especially for the initiation of EC use. 3,4 Although nicotine delivery to the aerosol can be similar or higher than tobacco cigarettes, 5,6 clinical studies of EC use have shown that the nicotine absorption potential is significantly lower compared with tobacco cigarettes, even when new generation devices are used. 7 This is mostly attributed to the low speed of nicotine absorption, and clearly indicates that nicotine intoxication is highly unlikely when ECs are used as intended.…”

“…There is already the example of regulatory decisions by the European Union, which defined an upper limit of 20 mg/ml nicotine concentration in EC liquids (http:// ec.europa.eu/health/tobacco/docs/dir_201440_en.pdf) based on information about potential nicotine delivery to the aerosol. 6 They failed to recognize that both effectiveness and abuse liability are determined by nicotine absorption (speed and amount delivered to the blood stream) rather than nicotine delivery to the aerosol. As a result, it is possible that such a restriction could exclude some smokers from effectively using ECs as smoking substitutes.…”