European Respiratory Journal
ERJ November 1, 2011 vol. 38 no. 5 1219-1220
Saliva cotinine levels in users of electronic cigarettes
J-F. Etter and C. Bullen
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]…
Because ENDS are purchased mainly on the internet [1, 2], we posted a questionnaire in English and French on the smoking cessation website Stop-Tabac.ch between September 2010 and January 2011. We asked discussion forums and websites informing about ENDS or selling them to publish links to the survey (http://www.stop-tabac.ch/fr_hon/ECIG_EN). The online questionnaire covered ENDS use (current/past and duration), smoking status, age, sex and postal address. Current ENDS users were sent by mail a plastic vial, a consent form and an additional questionnaire on paper, which covered ENDS use (days per week), brand and model, whether their current ENDS contained nicotine, nicotine dosage, puffs•day−1, refills•day−1, tobacco cigarettes per day (in smokers), quit date (in ex-smokers) and any tobacco, nicotine replacement therapy (NRT) and ENDS use in the previous 48 h. Participants were aged >18 yrs and the study was approved by the ethics committee of the Geneva University Hospitals (Geneva, Switzerland)…
We found substantial amounts of cotinine in the saliva of ENDS users. These results contrast with two laboratory reports that concluded that ENDS did not reliably increase blood nicotine levels , or provided lower levels than nicotine inhalers or tobacco cigarettes . The differences with our study may be explained by different durations of exposure, users’ experience with the devices, puffing characteristics, models used and the swallowing of nicotine. In our study, experienced users puffed intensively and had been using ENDS regularly for months, whereas the previous studies were conducted in ENDS-naïve users. Experience with the device is likely to have influenced blood nicotine/cotinine levels. The correlation between puff number and cotinine suggests that puffing topography is an important factor that should be controlled for in future studies…
Nevertheless, cotinine levels in ENDS users were similar to levels previously observed in smokers  and higher than levels previously found in NRT users [7, 8]. Cotinine levels are roughly similar when measured in blood or in saliva [6, 9, 10], so studies using cotinine in blood and in saliva can be compared. Participants had not smoked for ≥20 days and had not used NRT or smokeless tobacco for ≥48 h (about three times the half-life of cotinine in smokers) . Thus, results are unlikely to be contaminated by other sources of nicotine. All participants but one were former smokers, suggesting that ENDS are used much like NRT, to assist quitting, with similar or even larger effects on nicotine exposure. In this light, it seems logical to apply the same evaluation requirements to ENDS as to NRT. Even though propylene glycol is authorised as an additive in foods and medications, the effects of repeatedly inhaling a vapour containing propylene glycol over long periods are unknown..
We conclude that cotinine levels in ENDS users were similar to levels observed, in previous reports, in smokers and higher than levels usually observed in NRT users. This finding has important implications for ENDS use by smokers who want to quit, for future research, and for the regulation of these products.
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