A significant reduction in type 2 deiodinase ( D2 ) activity of 12.5 d placenta was found in 3.0 mg/L or above groups.

• 12．5d胎盘和19．5d子宫2型脱碘酶的活性显著降低,19．5d子宫3型脱碘酶的活性显著升高。