Reductions in biomarkers of exposure (BoE) to harmful or potentially harmful constituents (HPHCs) following partial or complete substitution of cigarettes with electronic cigarettes in adult smokers

Abstract

Changes in fifteen urine, blood and exhaled breath BoEs of HPHCs representing classes of compounds reported by FDA to be significant contributors to smoking-associated disease risks were measured in 105 clinical-confined subjects following randomization and a five-day forced-switch from usual brand conventional combustible cigarettes to: (i) exclusive commercial e-cigarette use; (ii) dual-use of commercial e-cigarettes and the subject’s usual cigarette brand; or (iii) discontinued use of all tobacco or nicotine products. Levels of urinary biomarkers in subjects that completely substituted their usual cigarette with e-cigarettes were significantly lower (29–95%) after 5 days. Percent reductions in eight of nine urinary BoEs were indistinguishable to smokers who had quit smoking, except for nicotine equivalents, which declined by 25–40%. Dual users who halved self-reported daily cigarette consumption with e-cigarettes exhibited reductions (7–38%) in eight of nine urinary biomarkers, but had increase (1–20%) in nicotine equivalents. Reductions were broadly proportional to the reduced numbers of cigarettes smoked. Dual user urinary nicotine equivalents were slightly higher, but not statistically significant. After 5 days, blood nicotine biomarker levels were lower in the cessation (75–96%) and exclusive use groups (11–83%); with dual users experiencing no significant reductions. All subjects experienced significant decreases in exhaled CO. Decreases in the cessation and exclusive groups ranged from 88–89% and 27–32% in dual users. Exhaled NO increased in the cessation and exclusive groups (46–63% respectively), whereas the dual users experienced minimal changes. Overall, smokers who completely or partially substituted conventional cigarettes with e-cigarettes over five days, experienced reductions in HPHCs.

Comparing the cancer potencies of emissions from vapourised nicotine products including e-cigarettes with those of tobacco smoke

“…Biomarkers for the same compounds declined rapidly in smokers switching to ECs at rates similar to abstinence from smoking over 5 days 52. Neither compound is normally detectable in EC vapour yet both have been shown above to account collectively for more than three-quarters of the cancer potency of tobacco smoke 53.…”

A Review of Pulmonary Toxicity of Electronic Cigarettes in the Context of Smoking: A Focus on Inflammation

“…CO also was substantially reduced. O’Connel et al (219, 220), reported on a five day trial of 105 subjects confined to a clinical facility; they found similar reductions in the urinary biomarkers and CO. Lastly, a one-year clinical trial reported significant reductions in exhaled CO (221). Thus, compared to smoking, there appears to be a significant overall reduction in biomarkers for persons completely switching to e-cigs, but it is not known if these peripheral biomarkers reflect effects in the lung.…”

“…Four switching studies showed a decrease FeNO (219, 221, 224, 225) (including a 1-year trial), while another found no difference (226), and another with methodological limitations (i.e., e-cigs and controls were tested on different days) reported an increase (227). …”

Key issues surrounding the health impacts of electronic nicotine delivery systems (ENDS) and other sources of nicotine

“…A medium‐term biomarker study has shown that, while complete switching to either NRT or e‐cigarettes overwhelmingly reduces exposure to tobacco‐related toxicants, dual use is not associated with any reduction compared with individuals who only smoke . Shorter term studies have shown reductions in toxicants for dual users that are commensurate with the reduction in cigarettes smoked . However, even if dual users displace some tobacco cigarette smoking without adding to nicotine consumption, which represents something of a best‐case scenario, then this may still be of limited potential benefit .…”