Stimulated embryo production as a parameter of estrogenic exposure via sediments in the freshwater mudsnail Potamopyrgus antipodarum

The effects of three suspected endocrine disrupting chemicals, the xeno-estrogens bisphenol A (BPA), 4-tertoctylphenol (OP) and 4-n-nonylphenol (NP), were investigated in a whole-sediment biotest with the freshwater mudsnail Potamopyrgus antipodarum (Gastropoda, Prosobranchia). Artificial sediments were spiked with five nominal concentrations (six for NP), ranging from 1-300 mug/kg dry weight (1-1000 pg/kg for NP). After 2, 4 and 8 weeks of exposure, the responses of the test species were analysed. P. antipodarum exhibited a distinct increase in the number of embryos sheltered in its brood pouch in a time- and concentration-dependent manner in comparison to the solvent control sediment for BPA and OP. The number of "new", still unshelled embryos turned out to be the most sensitive parameter. The lowest observed effect concentration (LOEC) was equivalent to the lowest administered concentration (1 mug/kg for each test compound) for most parameters after 8 weeks of exposure. The calculation of effect concentrations resulted in even lower values for BPA (unshelled embryos after 2 weeks: EC10 0.22 mug BPA/kg, EC50 24.5 mug BPA/kg; after 4 weeks: EC10 4 ng OP/kg, EC50 5.67 mug OP/kg) and OP (unshelled embryos after 4 weeks: EC10 4 ng OP/kg, EC50 0.07 mug OP/kg). For NP, there was no clear concentration-dependent response, and therefore, no EC10 or EC50 could be estimated, but the data suggest an inverted u-shape type of curve. The LOEC in the experiments with NP was 10 pg/kg. Our results indicate that P. antipodarum is highly sensitive to the tested endocrine disruptors at environmentally relevant concentrations. Furthermore, the biotest with P. antipodarum is a useful tool for the identification of sediment-bound pollutants and for the assessment of sediment quality. (C) 2003 Elsevier Science B.V. All rights reserved.