Probabilistic risk assessment of hazardous VOCs and carbonyl compounds in mainstream and secondhand cigarette smoke...

Volatile organic compounds (VOCs) and carbonyl compounds in mainstream cigarette smoke (MCS) and sidestream cigarette smoke (SCS) may contribute considerably to respiratory and carcinogenic health risks for both active and passive smokers. In this study, we quantified selected VOCs and carbonyl compounds in MCS and SCS from ten popular commercial cigarette brands sold in Korea. Maximum emission yields varied significantly by compound and the applied machine-smoking regimens, specifically the standard International Organization for Standardization (ISO) and the Health Canada Intense (HCI) protocols. Under these evaluated regimens, acetaldehyde yields reached up to 986 μg/cig in MCS and 2203 μg/cig in SCS. Secondhand smoke (SHS) concentrations in indoor and outdoor microenvironments were estimated using mechanistic single-compartment mass-balance (SMB) models combined with Korean-specific exposure factors. The calculated uptake ratios comparing MCS to SHS ranged broadly from 2.84 to 1098 under single-compartment assumptions. However, in the immediate breathing zone, these ratios dropped to a range of 0.06-9.53, indicating that while active smoking generally accounted for the majority of total inhalation exposure, SHS still contributed notable additional doses. For certain compounds like acrylonitrile, benzene, and formaldehyde, estimated SHS risks occasionally equaled or exceeded those of MCS. Probabilistic risk assessments using Monte Carlo simulations derived incremental lifetime cancer risks (ILCRs) and hazard quotients (HQs) that frequently exceeded commonly accepted safe levels. Specifically, the estimated median ILCRs for acetaldehyde ranged from 2.81 × 10⁻⁴ to 8.06 × 10⁻⁴. Furthermore, the median HQs for acrolein peaked between 768 and 2883. These quantitative outcomes suggest that both MCS and SHS exposures might pose substantial cancer and non-cancer health risks. The modeling framework provides a transferable strategy for quantitative risk assessments, which can be adapted to other populations by substituting population-specific exposure factors.