--> This is a substudy of the main ESTxENDS trial (NCT03589989). Toxins outcomes should be considered secondary outcomes of the main smoking cessation outcome formulated in NCT03589989.
Cigarette smoking is the leading cause of preventable death in Switzerland. Recently, electronic nicotine delivery systems (ENDS; also called vaporizer or electronic cigarette) have become popular with smokers who want to stop smoking or reduce their exposure to inhaled chemicals since ENDS use appears to be safer than tobacco smoking.
Conventional cigarettes release toxic chemicals in tobacco smoke through thermochemical degradation and pyrolysis processes by combusting tobacco, but in ENDS toxicants can be released by heating up nicotine-containing e-liquids to produce vapor. The e-liquid in ENDS is mostly made of propylene glycol (PG) and vegetal glycerin (VG) in addition to nicotine, flavorings and sometimes alcohol as a conservation agent. The heating process of the e-liquid in ENDS, has been shown to release carcinogens such as some carbonyl and volatile organic compounds (i.e., formaldehyde, acetaldehyde and acrolein). Some devices might also release heavy metals such as cadmium, lead and mercury. The source of such metals may be the metal of the device or the e-liquids. Although unexpected from the composition of the e-liquids, some studies have also detected tobacco-specific nitrosamines (TNSAs) (N'-nitrosonornicotine (NNN) and 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK)) and polycyclic aromatic hydrocarbons (PAHs) (1- and 2-Naphtol and 1-hydroxypyrene (1-OHP)).
This study will therefore test the efficacy of ENDS for cigarette smoking cessation, the safety of ENDS on adverse events and the effect of ENDS on health-related outcomes and exposure to inhaled chemicals.
For the main ESTxENDS trial (NCT03589989), cigarette smokers motivated to quit smoking cigarettes will be included. Participants in the intervention group will receive an ENDS and nicotine-containing e-liquids, which they will be allowed to use ad libitum. Additionally, they will receive smoking cessation counseling. Participants in the control group will receive smoking cessation counseling only. All participants will be followed over a 24-month period. Chemicals such as VOCs, PAHs, TSNAs, heavy metals, nicotine and nicotine degradation products will first be quantified in the aerosol produced by ENDS in laboratory conditions. These chemicals and their metabolites will then be measured at baseline and at 6-, 12- and 24- months' follow-up in urine samples from study participants.
