This randomized, controlled study in 110 male and female adult smokers evaluated biomarkers of tobacco smoke exposure (carbon monoxide [CO], carboxyhemoglobin [CO-Hb], nicotine, urine mutagenicity) under controlled smoking conditions when adult smokers of 1 conventional cigarette brand (CC1) were switched to an electrically heated cigarette smoking system (EHCSS) or a low-tar conventional cigarette (CC2). Baseline exposure was determined while all subjects smoked CC1. Subjects then were stratified for gender and cigarette consumption and randomized to 1 of 5 groups-EHCSS1, EHCSS2, CC1, CC2, or no smoking-and monitored for 8 days. Compared to baseline, biomarkers of exposure on day 8 decreased 53% to 93% (P < .0001) for EHCSS groups and 18% to 39% (P < .02) for CC2. Environmental tobacco smoke arising from the smoking activities of the different study groups was measured in the air of a separate smoking room over 1-hour periods. Concentrations of respirable suspended particulates in both EHCSS groups were about 90% lower than in the CC1 and CC2 groups, similar to the 95% reduction in the no-smoking group. CO was undetectable in the EHCSS and no-smoking groups. Results from this short-term clinical study indicate that switching from a conventional cigarette to a first-generation EHCSS reduces the generation of environmental tobacco smoke and can reduce the exposure to the measured, potentially harmful constituents in tobacco smoke if smokers do not compensate by numbers of cigarettes. The study design was found to be suitable for the evaluation of the exposure of adult smokers to the measured smoke constituents and to allow the differentiation of different cigarette designs.

The viscosity of liquid mixtures in e-vapor products (EVPs) is key to their performance and is sensitive to mixture composition and temperature. To date, no accurate model exists for the viscosities of said mixtures. Herein, we report an empirical model for the viscosity of liquid mixtures containing propylene glycol (PG), glycerol (GL), and water (W), representative of the mixtures in EVPs. The model captures the interactions between component liquids and makes accurate viscosity predictions for liquid mixtures of PG, GL, and W, as well as such mixtures containing small amounts of menthol, from 20 to 80 °C. The model is calibrated to new experimental data for PG–GL–W ternary mixtures and may be extended to incorporate different or additional liquids or a wider temperature range given additional fitting data. The model should also prove beneficial for food, cosmetic, and pharmaceutical products containing aqueous solutions of PG and GL.

SUMMARYThis substudy of a randomized, controlled, forced switching, open-label, parallel-group clinical study in a total of 100 healthy adult male and female smokers compared environmental tobacco smoke (ETS) produced from smoking a second generation electrically heated cigarette smoking system (EHCSS), two conventional cigarettes, and no-smoking. Concentrations of air constituents including respirable suspended particulate matter (RSP), carbon monoxide (CO), and total volatile organic compounds (TVOCs) and ETS markers including solanesolrelated particulate matter (Sol-PM), ultraviolet absorbing particulate matter (UVPM), fluorescing particulate matter (FPM), nicotine and 3-ethenylpyridine (3-EP) were measured in a ventilated, furnished conference room over a period of 2 hours on separate occasions. Except for TVOCs, concentrations of air constituents and ETS markers were reduced by 40% to more than 90% when adult smokers were smoking the EHCSS as compared to smoking conventional cigarettes. CO and most ETS marker concentrations were in the same range as nosmoking. [Beitr. Tabakforsch. Int. 23 (2008)