Comprehensive Health Risk Assessment of Electronic Cigarette Aerosols: Metal and PAH Characterization, Oxidative Potential, and Cancer Risk Estimation.

Electronic cigarettes (ECs) have emerged as popular alternatives to traditional cigarettes (TCs), yet their health impacts remain contentious due to limited systematic evaluations integrating multiple toxicological end points. This study provides a comprehensive assessment of EC aerosol toxicity by combining chemical characterization, oxidative potential (OP) measurement, and health risk modeling with systematic cross-study comparisons. Chemical analysis revealed that five metals (Cu, Ni, Ag, Zn, and Pb) originate exclusively from device components, while cross-study comparison identified substantial heterogeneity in metal profiles across different devices and studies. PAH analysis detected 14 compounds with a total concentration of 1.373 ng/puff. OP measurements demonstrated a marked dichotomy between OPv (49.87 nmol/min/m3) and OPm (0.02 pmol/min/μg), indicating that particle number and surface area, rather than mass alone, are key determinants of EC aerosol oxidative toxicity. ELCR estimates ranged across 3 orders of magnitude (10-6 to 10-3), with chromium oxidation state (Cr3+ vs Cr6+) representing the single largest source of uncertainty. Compared to TC emissions, which are primarily driven by combustion, EC aerosols represent a fundamentally different type of exposure whose chemical composition and health risks vary greatly with device design, coil materials, and operating conditions. These findings demonstrate that EC risk is device-structured and endpoint-specific, and that risk characterization depends critically on the choice of chemical species, analytical panels, and exposure metrics being evaluated. Therefore, comprehensive and rigorous evaluation of EC health risks requires careful consideration.