Evaluation of E-Vapor Nicotine and Nicotyrine Concentrations under Various E-Liquid Compositions, Device Settings, and Vaping Topographies

Abstract

Nicotine is one of the major components of electronic cigarette (e-cigarette) emissions. Nicotyrine is a product of nicotine dehydrogenation in e-vapor and is a known inhibitor of human cytochrome P450 enzyme, which mediates nicotine metabolism. However, the emission of nicotine and especially nicotyrine from e-cigarettes has not been studied under real-world vaping patterns. This study examined the impact of e-liquid composition, e-cigarette device power output, and vaping topography on nicotine and nicotyrine concentrations under real-world vaping patterns. The amount of nicotine emitted from e-cigarettes vaped at high e-liquid nicotine levels, high device power, and large puff volumes ranged from 0.365 μg/puff to 236 μg/puff and was comparable to the amount of nicotine emitted from regular cigarettes. E-cigarette coil temperatures (200-300 °C) favored the formation of nicotyrine: E-cigarette vaping generated 2- to 63-fold more nicotyrine per unit nicotine emission than conventional cigarette smoking. High nicotyrine emission from e-cigarettes indicates that nicotine metabolism could be potentially interrupted, which could lead to reduced e-cigarette usage, and result in lower exposures to toxic chemicals (e.g., formaldehyde and acetaldehyde). However, higher serum nicotine levels might increase cancer risks by stimulating nicotinic acetylcholine receptors (nAchRs).

Addressing the challenges of E-cigarette safety profiling by assessment of pulmonary toxicological response in bronchial and alveolar mucosa models

“…Therefore, p-benzoquinone in E-smoke warrants major attention. Nicotyrine, is found in much higher concentration in E-smoke than in conventional cigarette smoke 50,51 . It is formed by oxidation of nicotine in the E-liquid and may increase nicotine levels in the blood stream by irreversibly binding hepatic CYP2A6 53 .…”

Carbonyls and Carbon Monoxide Emissions from Electronic Cigarettes Affected by Device Type and Use Patterns

“…The effect of puff topography was tested by controlling either puff duration or puff flow rate (Table 1). The puffing parameters used in this study cover the range of e-cigarette vaping topography data reported in the literature (80.4-133 mL volume and 3.3-4.16 s duration) [18,19,[31][32][33]. A square-shaped flow profile was used as it was observed during actual e-cigarette use [19,34].…”

“…Puff durations employed by users of the same e-cigarette device were reported to vary from 0.6 s to over 10 s [18]. In a study of 23 daily e-cigarette users, e-cigarette power output was reported to vary between 5 and 60 W, puff volume varied between 10-251 mL, and puff duration between 1.3 and 5.8 s [19]. Understanding of the relative importance of different parameters affecting e-cigarette emissions is needed for formulating standardized testing protocols and translating laboratory results to real-life exposure.Carbon monoxide (CO) emissions from e-cigarette have been understudied [20,21], because a few studies showed that exhaled CO concentrations among e-cigarette users were significantly lower than conventional tobacco smokers [7,[22][23][24].…”

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

“…E-vapors were generated based on the protocols used in our previous studies [27][28][29]. In brief, vaping topographies of 23 current e-cigarette users measured in our lab.…”