Effects of nonylphenol ethoxylate exposure on reproductive output and bioindicators of environmental estrogen exposure in fathead minnows, Pimephalespromelas

Nonylphenol ethoxylates (NPEOs) were evaluated in the laboratory for potent ial effects on the reproductive physiology and fecundity of fathead minnows (Pimephales promelas). Groups of three adult male and three female fathead minnows were exposed in a continuous flow-through system to 0, 0.21, 0.65, 2.1, or 7.9 mug NPEO/L for 42 d. Rabbit anti-goldfish vitellogenin (VTG) a ntiserum was prepared and a competitive enzyme-linked immunosorbent assay ( ELISA) was adapted for measurement of plasma VTG in fish following exposure . Plasma 17 beta -estradiol (E2) and testosterone (T) were also quantified by ELISA at the end of the exposure. Neither survival nor fecundity of fath ead minnows exhibited a concentration-dependent response to NPEOs. No signi ficant differences were observed in plasma VTG concentrations among treatme nts for males or females. Mean plasma VTG concentrations in females ranged from 291.7 to 895.1 mug VTG/ml among treatments and did not overlap with me an concentrations measured in the plasma of males, which ranged from less t han the method detection limit (0.27 mug VTG/ml) to 3.2 mug VTG/ml. Plasma E2 concentrations exhibited a significant difference between males and fema les within all NPEO treatments, but no differences were observed among trea tments. Similarly, plasma T concentrations did not exhibit a concentration- dependent response to NPEOs.