Human health risk assessment of soil dioxin/furans contamination and dioxin-like activity determined by ethoxyresorufin-O-deethylase bioassay

The major objective of this study was to evaluate the human health risks of agricultural land use conversion to other purposes in Hong Kong, based on the levels of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/Fs) and determined dioxin-like activity in soil using ethoxyresorufin-O-deethylase (EROD) bioassay. Hazard quotient showed soils of open burning site (OBS) and electronic waste open burning site (EW (OBS)) exert a relatively higher non-cancer risk on adults (50.9 and 8.00) and children (407 and 64.0) via the pathway of accidental ingestion of soil particles than other types of land use. In addition, the levels of 17 PCDD/Fs congeners in OBS and EW (OBS) soils indicated high and moderate (1654 and 260 in one million people) cancer risks through the above pathway. Furthermore, the biologically derived TCDD concentrations (TEQ_bio) were also significantly correlated to the chemically derived toxic equivalent concentrations of dioxin-like chemicals (TEQ_cal (sum of chemically derived 2,3,7,8-TeCDD toxic equivalent concentrations (TEQ_PCDD/F) and chemically derived dioxin-like PAHs toxic equivalent concentrations (TEQ_PAH)) (r = 0.770, p <0.05). PCDD/Fs (95.4 to 99.9 %) were the major stressor to the TEQ_cal in the soil samples, indicating higher concentrations of PCDD/Fs derived from chemical analyses may reflect a higher potency of inducing EROD activity.