Reduction of harmful or potentially harmful constituents (HPHCs) following partial or complete substitution of cigarettes with electronic cigarettes in adult smokers
Changes in fifteen urine, blood, and exhaled breath biomarkers of exposure (BoE) to harmful and potentially harmful constituents (HPHCs), representing major classes of compounds reported by the FDA to be significant contributors to smoking-associated disease risks, were measured in 105 randomized and clinical-confined subjects following a five-day forced-switch study from usual brand conventional combustible cigarettes to: (i) exclusive use of commercial e-cigarettes; (ii) dual-use of commercial e-cigarettes and the subject’s usual conventional cigarette brand; or (iii) discontinued use of all tobacco or nicotine products. Levels of urinary biomarkers in subjects that completely substituted their usual cigarette brand with e-cigarettes were significantly lower (29%-95%) after five days. Percent reductions in eight of the nine urinary BoEs measured were indistinguishable to smokers who had quit smoking, with the exception of nicotine equivalents, which were reduced by 25%-40%. Dual users who halved their self-reported daily cigarette consumption of conventional cigarettes with e-cigarettes exhibited reductions of 7%-38% in eight of nine urinary biomarkers, with a statistically insignificant 1%-20% increase in nicotine equivalents. The observed reductions in the dual use group were broadly proportional to the reduced numbers of cigarettes smoked. After five days, blood nicotine biomarker levels were lower in subjects in the cessation (75%-96%) and exclusive groups (11%-83%); dual users did not experience any significant reductions. All subjects experienced significant decreases in exhaled CO, with decreases in cessation and exclusive groups ranging from 88%-89% and in the dual group from 27%-32%. Exhaled NO was observed to increase in cessation and exclusive groups (46%-63% respectively), whereas the dual user group experienced minimal changes. This study indicates that smokers who completely or partially substitute conventional tobacco cigarettes with e-cigarettes over five days experienced reductions in BoEs associated with exposure to a number of select HPHCs. While exclusive e-cigarette users displayed similar reductions to smokers who quit smoking over the same period of time.