Nicotine delivery efficiency of first- and second-generation e-cigarettes and its impact on relief of craving during the acute phase of use.

Knowledge about the change in blood nicotine concentrations during the first five minutes (acute phase) of e-cigarette vaping is important to determine whether the used product has a dependence potential or may be an efficient nicotine replacement product. To address this issue, we monitored blood nicotine levels during the acute phase in volunteers using disposable cigalikes (CLs) and a tank model (TM) and compared them with blood nicotine levels in subjects using a tobacco cigarette (TC). In parallel, heart rate changes were continually measured and withdrawal symptoms and craving were assessed with the Questionnaire on Smoking Urges before and immediately after the vaping/smoking sessions. Additionally, at the end of each session negative health effects were rated on a visual analog scale. After five minutes of e-cigarette or TC use, the mean nicotine plasma concentrations were as follows: CLs, 5.5ng/ml; TM, 9.3ng/ml; TC, 17.1ng/ml. Nicotine levels increased significantly faster in the first 4min of consuming a TC than with the CLs and the TM. The highest rate of increase in nicotine concentration was found with the TC (6.8ng/ml) and TM (2.3ng/ml) between the 1st and 2nd minute, whereas the CLs showed comparatively small changes in the amount delivered over the five minutes. Withdrawal and craving for smoking decreased with the TM by the same amount as with the TC, even though less nicotine was delivered to the blood and considerably fewer side effects occurred. The heart rate of TM users was also markedly lower than that of the TC users. Unlike CLs, TM e-cigarettes represent an effective source of nicotine and might be used as an alternative nicotine replacement product to aid smoking cessation. However, nicotine plasma levels observed in TM users after short-time vaping have also the potential to produce and sustain nicotine addiction.

Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers.

Despite the recent popularity of e-cigarettes, to date only limited data is available on their safety for both users and secondhand smokers. The present study reports a comprehensive inner and outer exposure assessment of e-cigarette emissions in terms of particulate matter (PM), particle number concentrations (PNC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), carbonyls, and metals. In six vaping sessions nine volunteers consumed e-cigarettes with and without nicotine in a thoroughly ventilated room for two hours. We analyzed the levels of e-cigarette pollutants in indoor air and monitored effects on FeNO release and urinary metabolite profile of the subjects. For comparison, the components of the e-cigarette solutions (liquids) were additionally analyzed. During the vaping sessions substantial amounts of 1,2-propanediol, glycerine and nicotine were found in the gas-phase, as well as high concentrations of PM2.5 (mean 197 µg/m(3)). The concentration of putative carcinogenic PAH in indoor air increased by 20% to 147 ng/m(3), and aluminum showed a 2.4-fold increase. PNC ranged from 48,620 to 88,386 particles/cm(3) (median), with peaks at diameters 24-36 nm. FeNO increased in 7 of 9 individuals. The nicotine content of the liquids varied and was 1.2-fold higher than claimed by the manufacturer. Our data confirm that e-cigarettes are not emission-free and their pollutants could be of health concern for users and secondhand smokers. In particular, ultrafine particles formed from supersaturated 1,2-propanediol vapor can be deposited in the lung, and aerosolized nicotine seems capable of increasing the release of the inflammatory signaling molecule NO upon inhalation. In view of consumer safety, e-cigarettes and nicotine liquids should be officially regulated and labeled with appropriate warnings of potential health effects, particularly of toxicity risk in children.