Levels and profiles of polychlorinated dibenzo-p-dioxin and dibenzofurans in raw and treated water from water treatment plants in Shenzhen, China.

Levels and profiles of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) were analyzed for the first time in raw and treated water from five water treatment plants in Shenzhen, South China. The average PCDD/Fs concentrations were 32.93 pg/L (0.057 pg international toxic equivalent quantity (I-TEQ)/L) and 0.64 pg/L (0.021 pg I-TEQ/L) in raw and treated water, respectively. The removal rate of PCDD/Fs in terms of mass concentration varied from 93.4% to 98.8%, whereas a negative removal rate was observed in one plant in terms of TEQ concentration. The PCDD/Fs concentration in raw water was lower than most of the published data from other countries and regions, and the PCDD/Fs concentration in treated water was below the Maximum Contaminants Level (MCL) of 30 pg/L for dioxin in drinking water set by the US EPA. Historical pentachlorophenol usage, local waste incineration and industrial emissions, as well as surface runoff or even soil erosion, might be the main sources for PCDD/F pollution in water. The daily intake of PCDD/Fs for local residents from drinking water was estimated to be 0.69 fg I-TEQ/kg/day, which is negligible compared with that from food consumption (1.23 pg WHO-TEQ/kg/day) in the local area.

Elevated body burdens of PBDEs, dioxins, and PCBs on thyroid hormone homeostasis at an electronic waste recycling site in China.

A cross-sectional study of 25 sample sets (each set consisted of maternal serum and cord whole blood) from 50 pregnant women in zone A (n = 25 from exposed group) and zone B (n = 25 from reference group) was conducted to examine the association between thyroid hormone (TH) levels and PBDE, PCDD/F, and PCB exposures. Thyroid hormones TT3, TT4, and TSH levels were measured in maternal serum at 16 weeks of gestation. The concentrations of PBDEs, PCDD/Fs, and PCBs were determined by isotope dilution HRGC/HRMS in cord blood samples. Body burdens of the three contaminants in cord blood in zone A (median: summation sigma TEQ-PCDD/Fs 0.041, summation operator TEQ-PCBs 0.022 pg WHO-TEQ/g, summation operator PBDEs 23.4 pg/g whole weight, respectively) were significantly higher than those from the reference area (median: summation sigma TEQ-PCDD/Fs 0.014, summation sigma TEQ-PCBs 0.0041 pg WHO-TEQ/g, summation sigma PBDEs 16.15 pg/g, respectively) (p < 0.05). Levels of TT4 and TSH in serum in zone A were significantly lower than those in zone B (p < 0.05). A negative correlation was found between TT4 levels and body burdens of PCDD/Fs and PCBs. However, there was no significant association of concentration of PBDEs and levels of the three thyroid hormones. Our results suggest that electronic waste (e-waste) recycling contributes to high body burdens of PBDEs, PCDD/Fs, and PCBs and affects thyroid hormone homeostasis in humans. The potential health risk for neonates still needs further investigation.