Low Tar Level Does Not Reduce Human Exposure to Polycyclic Aromatic Hydrocarbons in Environmental Tobacco Smoke

Environmental tobacco smoke (ETS) is known to pose potential risk to human health, but the effects of tar level remain to be clarified. In the present study, ETS samples from two cigarette types with different tar levels in a 72.5 m³ room were collected for measurement of 16 polycyclic aromatic hydrocarbons (PAHs). Urine samples of volunteers participating in smoking events were collected and analyzed for eight hydroxyl-PAHs. The concentrations, compositions, and particle size distribution patterns of PAHs from higher-tar and lower-tar cigarettes were similar, while the emission factors of PAHs from higher-tar cigarettes were lower than those from lower-tar cigarettes. Furthermore, the change in the concentrations of PAH metabolites in urine samples before and after smoking was not attributed to tar level. Assuming that a single cigarette was smoked in a 100 m³ room, the estimated average inhalation cancer risks for different age groups from exposure to PAHs in ETS were below 1.0 × 10^-6, but potential risks should not be overlooked, especially considering that only inhaled particle-bound PAHs in ETS were included in this assessment. Apparently, reduced tar levels would not necessarily lead to lowered risk of exposure to PAHs. Kicking the habit is perhaps the best choice to minimize any potential health risk.