Background Given the rapid increase in e-cigarette (EC) popularity and paucity of longitudinal health-related data associated with this, there is an urgent need to assess the potential risks of long-term EC use. Objective To compare exposure to nicotine, tobacco-related carcinogens and toxicants among cigarette-only smokers, and smokers and ex-smokers with long-term EC use or with use of nicotine replacement therapy (NRT; a product with known safety profile). Design Cross-sectional study. Setting United Kingdom. Participants Five groups were purposively recruited: (1) cigarette-only users, (2) ex-smokers with long-term (≥6 months) EC-only or (3) NRT-only use, and (4) long-term dual cigarette-EC or (5) dual cigarette-NRT users (N=36-37 per group, total N=181). Measurements Socio-demographic and smoking characteristics were assessed; participants provided urine and saliva samples, analysed for biomarkers of nicotine, tobacco-specific nitrosamines (TSNAs) and volatile organic compounds (VOCs). Results After controlling for confounders, there were no clear group differences in salivary or urinary biomarkers of nicotine intake. EC-only and NRT-only users had significantly lower metabolite levels for TSNAs (including the carcinogenic metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, NNAL) and for VOCs (including metabolites of the toxicants acrolein, acrylamide, acrylonitrile, 1,3-butadiene, ethylene oxide) compared with cigarette-only, dual cigarette-EC or cigarette-NRT users. EC-only users had significantly lower NNAL levels than all other groups. Cigarette-only, dual cigarette-NRT and cigarette-EC users had largely similar levels of TSNA and VOC metabolites. Limitations Cross-sectional design with self-selected sample. Conclusions Ex-smokers with long-term EC-only or NRT-only use may achieve approximately similar nicotine intake to cigarette-only smokers but results were variable. Long-term NRT-only and EC-only use, but not dual use with cigarettes, is associated with substantially reduced levels of measured carcinogens and toxicants relative to cigarette-only smoking. Primary source of funding Cancer Research UK (C27061/A16929).

BackgroundUp-to-date data tracking of national smoking patterns and cessation-related behaviour is required to evaluate and inform tobacco control strategies. The Smoking Toolkit Study (STS) was designed for this role. This paper describes the methodology of the STS and examines as far as possible the representativeness of the samples.MethodsThe STS consists of monthly, cross sectional household interviews of adults aged 16 and over in England with smokers and recent ex-smokers in each monthly wave followed up by postal questionnaires three and six months later. Between November 2006 and December 2010 the baseline survey was completed by 90,568 participants. STS demographic, prevalence and cigarette consumption estimates are compared with those from the Health Survey for England (HSE) and the General Lifestyle Survey (GLF) for 2007-2009.ResultsSmoking prevalence estimates of all the surveys were similar from 2008 onwards (e.g 2008 STS = 22.0%, 95% C.I. = 21.4% to 22.6%, HSE = 21.7%, 95% C.I. = 20.9% to 22.6%, GLF = 20.8%, 95% C.I. = 19.7% to 21.9%), although there was heterogeneity in 2007 (chi-square = 50.30, p < 0.001). Some differences were observed across surveys within sociodemographic sub-groups, although largely in 2007. Cigarette consumption was virtually identical in all surveys and years.ConclusionThere is reason to believe that the STS findings (see http://www.smokinginengland.info) are generalisable to the adult population of England.