Saliva cotinine levels in users of electronic cigarettes

Abstract

To the Editors: Electronic nicotine delivery systems (ENDS or electronic cigarettes) look like cigarettes but do not contain or burn tobacco. Instead, they comprise a battery-powered atomiser that produces a vapour for inhalation from cartridges containing humectants (propylene glycol or glycerol), flavours ( e.g. tobacco, mint or fruit) and nicotine. Many smokers report using ENDS to quit smoking or to substitute for tobacco in smoke-free places [1, 2]. ENDS do attenuate craving for tobacco, but appear to deliver little nicotine to the blood [3, 4]. Two studies have evaluated nicotine administration with different ENDS brands in ENDS-naïve smokers [3, 4]. In one study, 32 smokers completed two 10-puff “vaping” bouts or smoked a cigarette [3]. In contrast to tobacco cigarettes, ENDS did not increase plasma nicotine reliably (plasma nicotine: 1.4 ng·mL−1 and 0.5 ng·mL−1, respectively, for two ENDS brands). In the other study, smokers used ENDS with a 16-mg nicotine cartridge for 5 min, a nicotine inhaler for 20 min or their usual cigarette for 5 min [4]. Nicotine concentration in plasma, measured after 60 min, was 1.3 ng·mL−1 for ENDS, 2.1 ng·mL−1 for inhalers and 13.4 ng·mL−1 for tobacco cigarettes, but one-third of participants showed no increase in blood nicotine while using the ENDS [4]. The time to maximum concentration of serum nicotine was shorter for ENDS (19.6 min) than for the nicotine inhaler (32.0 min), suggesting some absorption via the respiratory tract [4]. It is possible that serum nicotine levels would have been similar in ENDS and inhaler users, had ENDS users been allowed to use the devices for 20 min as for the inhaler. However, regular ENDS users may draw 120–175 puffs·day−1 on …