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: Sigma TEQ-PCDD/Fs 0.041, Sigma TEQ-PCBs 0.022 pg WHO-TEQ/g, Sigma PBDEs 23.4 pg/g whole weight, respectively) were significantly higher than those from the reference area (median: Sigma TEQ-PCDD/Fs 0.014, Sigma TEO-PCBs 0.0041 pg WHO-TEQ/g, 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.