Administration of low dose triclosan to pregnant ewes results in placental uptake and reduced estradiol sulfotransferase activity in fetal liver and placenta

•Low-dose triclosan was administered to pregnant ewes.•Higher triclosan concentrations were present in placenta than liver.•Estrogen sulfotransferase activity was reduced by triclosan treatment. Sulfonation is a major pathway of estrogen biotransformation with a role in regulating estrogen homeostasis in humans and sheep. Previous in vitro studies found that triclosan is an especially potent competitive inhibitor of ovine placental estrogen sulfotransferase, with Kic of