Biomarkers of Exposure and Potential Harm in Exclusive Users of Electronic Cigarettes and Current, Former and Never-Smokers: A Cross-Sectional Study Protocol

: Despite public health efforts to reduce the health burden of cigarettes by encouraging smoking cessation, a proportion of smokers remain unwilling to quit. A shift from smoking cessation to tobacco harm reduction, based on smokers switching completely to potentially less harmful products such as electronic cigarettes (ECs), has been proposed as an alternative strategy. This is a single-centre, cross-sectional confinement study, involving healthy exclusive Vuse EC users and current, former, or never-smokers. Exclusive EC use and smoking status will be confirmed by urinary cotinine and exhaled carbon monoxide levels. Participants will be confined for 24 hours, during which they will use their usual product (EC or cigarette) as normal. Biomarkers of exposure and potential harm will be analysed in 24-hour urine and blood and compliance will be measured using N-(2-cyanoethyl)valine. The primary objective is to quantitatively assess differences between EC users and current smokers in urinary total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and 8-epi-prostaglandin F 2α Type III, exhaled nitric oxide, and carboxyhaemoglobin, white blood cell count, soluble intercellular adhesion molecule-1, and high-density lipoprotein. Secondary objectives are to quantitatively assess differences between EC users and current smokers in selected urinary biomarkers of tobacco exposure, 11-dehydrothromboxane B2, forced expiratory volume in 1 second as a percentage of predicted, carotid intima-media thickness and a quality of life questionnaire. Endpoints will also be compared between EC users and former and never-smokers. The results of this study are anticipated to add to the current knowledge about the role of ECs in tobacco harm reduction.