Estrogenic effect of propylparaben (propylhydroxybenzoate) in rainbow trout Oncorhynchus mykiss after exposure via food and water

The estrogenic effect of propylparaben was investigated in a rainbow trout Oncorhynchus mykiss test system. Propylparaben was administered orally to sexually immature rainbow trout every second day for up to 10 days in doses between 7 and 1830 mg kg(-1) 2 d(-1) and in the water at 50 and 225 mug l(-1) for 12 days. Plasma vitellogenin was measured before and during the exposures and the concentrations of propylparaben in liver and muscle were determined at the end of experiments. Increases in average plasma vitellogenin levels were seen at oral exposure to 33 mg propylparaben kg(-1) 2 d(-1); the most sensitive fish responded to 7 mg kg(-1). The ED50 values for increase in vitellogenin synthesis were 35, 31 and 22 mg kg(-1) 2 d(-1) at day 3, 6 and 11, respectively. Exposure to 225 mug propylparaben l(-1) increased vitellogenin synthesis, but exposure to 50 mug l(-1) did not. Propylparaben showed little tendency to bioaccumulation in rainbow trout; less than 1parts per thousand of the total amount of propylparaben administered orally at 1830 mg kg(-1) 2 d(-1) over the 10-d experimental period was retained in muscle and liver 24 h after the end of the experiment. Exposure to 225 mug propylparaben l(-1) for 12 d led to concentrations of 6700 and 870 mug propylparaben kg(-1) liver and muscle, respectively. Half lives for propylparaben were 8.6 h in liver and 1.5 h in muscle. (C) 2003 Elsevier Inc. All rights reserved.