Spatial distribution and mass loading of phthalate esters in wastewater treatment plants in China: An assessment of human exposure

Abstract

The occurrence and fate of nine phthalate esters (PAEs), including dimethyl phthalate (DMP), diethyl phthalate (DEP), di‑n‑butyl phthalate (DBP), di-isobutyl phthalate (DIBP), benzyl butyl phthalate (BzBP), di (2‑ethylhexyl) phthalate (DEHP), di‑n‑hexyl phthalate (DNHP), dicyclohexyl phthalate (DCHP), and di‑n‑octyl phthalate (DNOP), in sludges collected from 46 wastewater treatment plants (WWTPs) from 22 Chinese provinces were investigated. The nine PAEs were detected in almost all the sludge samples. DEHP was the most abundant congener in all sludge samples, followed by DBP and DIBP. The DEHP concentrations in sludge were in the range of 0.326-67.8 (mean: 14.7) μg/g dry weight (dw), which were at the lower bound or middle of the concentration range of DEHP in sludge globally (0.0200-3514 μg/g dw). Spatial distribution and mass loading of PAEs in WWTPs were investigated. The concentrations of Σ₉PAEs in sludges from different provinces were in the order as follows: Jilin (40.2 μg/g dw) > Liaoning (38.9 μg/g dw) > Beijing (30.7 μg/g dw), while the mass loading of ∑₉PAEs in sludges were Guangdong (10.1 tons/yr) > Liaoning (9.97 tons/yr) > Shandong (5.59 tons/yr). Our study showed that the geographical distribution of PAEs in sludges was similar to that in indoor dusts found in earlier study, suggesting the existence of a common source for these chemicals in both matrices. Based on the concentrations measured, human exposure to PAEs through sludge application in soil was evaluated and the exposure dose is minor.

Keywords: Human exposure; Mass loading; Phthalate esters; Sludge; Spatial distribution.