Seasonal exposure to PM2.5-bound polycyclic aromatic hydrocarbons and estimated lifetime risk of cancer: A pilot study.

Limited researches are available on seasonal variation of inhalation exposure of polycyclic aromatic hydrocarbons (PAHs) and its cancer risk assessment in China. We recruited 20 fresh postgraduates and measured outdoor and indoor (dormitories, offices and laboratories) daily PM2.5 concentrations in four seasons (seven consecutive days in every season) during 2014 -2015, calculated daily potential doses of personal exposure to total Benzo[a]pyrene equivalent concentration (BaPeq) in the microenvironments based on the total BaPeq and the time-activity patterns, and estimated incremental lifetime cancer risk (ILCR) using Monte Carlo method. Daily average concentrations of PM2.5-bound ∑PAHs on the campus ranked from high to low were winter, autumn, spring, summer in the dormitories and offices. Daily average concentration of PM2.5-bound ∑PAHs were higher in indoor environments than outdoor in the same season, except for that of PM2.5-bound ∑PAHs in laboratories in the winter. Median values of ILCR in both sexes from high to low were winter (men vs. women: 5.35e-9 vs. 4.96e-9), spring (3.71e-9 vs. 4.00e-9), autumn (2.92e-9 vs. 3.02e-9), summer (1.71e-9 vs. 1.87e-9). Indoor and outdoor PM2.5-bound PAHs concentrations showed seasonal and spatial variations. The ILCR value for PM2.5-bound PAHs was higher in women than in men.