Introduction
Long-term health effects of e-vapor products (EVPs) are not well-established. We compared biomarkers of exposure (BoE) to select harmful and potentially harmful constituents (HPHCs) and biomarkers of potential harm (BoPH) in adult smokers (AS) who switched to EVPs vs continued smoking for 24 weeks.
Methods
AS (n=450, >10 cigarettes per day [CPD] for ≥10 years), were randomly assigned to continue smoking (Control) or switch to one of two cartridge-based EVPs (Test 1 - classic; Test 2 - menthol, 4% nicotine). BoE and BoPH were measured at baseline and 12 Weeks. A subset of 150 Control and EVP subjects (switchers with eCO ≤8 ppm and <10% baseline CPD) were followed to 24 weeks, the focus of this manuscript.
Results
Total NNAL and carboxyhemoglobin (COHb) were significantly reduced (p<0.0001) in Test 1 and Test 2 at 24 weeks. Urinary nicotine equivalents (NE) were not statistically significantly different between the Control and EVP groups. At Week 24, statistically significant reductions (p<0.05) were observed for white blood cell counts, 11-dehydrothromboxane β2, and sICAM in both test groups, and there were several significant changes in measures of pulmonary function. High-density lipoprotein-cholesterol (HDL-C) and 8-epi-prostaglandin-F2α were directionally favorable in both EVP groups vs Control.
Conclusions
We demonstrate that significant reductions of selected HPHCs in EVP aerosol results in significant reductions in BoEs and favorable changes in BoPHs after switching to EVPs for 24 weeks. These changes approached those reported for smoking cessation, suggesting that switching to exclusive use of the EVPs may be less harmful than continuing smoking.
Implications
Cigarette smoking causes serious diseases. Switching from cigarettes to a noncombustible product is a potential harm reduction pathway for AS unable or unwilling to quit. Long-term health effects of EVPs compared to continued smoking have not been extensively studied. We present BoE evidence on select HPHCs and BoPHs related to inflammation and oxidative stress in AS completely switching to two EVPs. This study demonstrates significant reductions in BoEs (except for nicotine) accompanied with favorable changes in various BoPHs, including pulmonary function. The totality of evidence suggests that exclusive EVP use may present lower health risks compared to smoking cigarettes.