Characterization of PM_2.5-bound phthalic acid esters (PAEs) at regional background site in northern China: Long-range transport and risk assessment

Eleven major phthalic acid esters (PAEs) congeners were analyzed for PM_2.5 samples collected at Mount Tai, a high elevation mountain site in northern China from June to August 2015. The results showed that the average concentration of PAEs in PM_2.5 was 19.48ngm^-3, and bis(2-Ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and diisobutyl phthalate (DIBP) were the predominant species in particle-phase, whereas diethyl phthalate (DEP) and dimethyl phthalate (DMP) were the prevailing PAEs in gas-phase. PAE concentrations decreased at the beginning of cloud/fog events, while they increased after the cloud/fog events since the liquid-phase PAEs could be absorbed by solid-phase PAEs. Potential source contribution function (PSCF) analysis and principal component analysis (PCA) revealed that the highest PSCF value of air masses were mainly sourced from southwest of Mount Tai and multiple sources contributed to PAEs. A Monte Carlo simulation was applied to estimate the incremental lifetime cancer risks (ILCR) from inhalation exposure on the basis of DEHP concentrations. The estimated values of ILCR for the general population were lower than the U.S. Environmental Protection Agency threshold, which is 10^-6. However, since the local population was exposed to various local emission sources, the actual health risk is undervalued.