Development and validation of a partial life-cycle test with Potamopyrgus antipodarum

Molluscs, though the second largest clade next to the arthropods, have widely been neglected in environmental risk assessment schemes for chemicals, mainly due to the lack of standardised and broadly accepted test guidelines for molluscs. However, they are known to be uniquely sensitive to a number of endocrine disrupting chemicals (EDCs, e.g. organotins) and other substances (e.g. copper). Therefore the German Federal Environment Agency and the Department for Environment, Food and Rural Affairs of the United Kingdom supported the preparation of a Detailed Review Paper (DRP) on Molluscs Life-cycle Toxicity Testing[1].The DRP proposed inter alia the parthenogenetic mud snail Potamopyrgus antipodarum as standard test organism. In the P. antipodarum reproduction test the number of embryos in the brood pouch, reflecting the individual reproduction effort in snails, and adult mortality serve as main endpoints. The present study aims to develop and validate the partial life-cycle test on the reproduction of P. antipodarum. Here, results from two pre-validation studies of the reproduction test with the chemicals tributyltin (TBT) with nominal concentrations of 10 - 400 ng TBT-Sn/L and cadmium with concentrations of 3.13 - 25 µg/L at eleven laboratories are presented. The mean embryo number in snails exposed to TBT decreased with increasing concentrations. First results show comparable NOEC (65 to 160 ng TBT-Sn/L) and LOEC (160 to 400 ng TBT-Sn/L) values for TBT. The EC10 was between 109 (95%-CI: 44.6 - 268) and 132 ng TBT-Sn/L (95%-CI: 58.8 - 329) indicating a good inter-laboratory reproducibility with a coefficient of variation between 8.4% (EC10) and 35.3% (LOEC). The good reproducibility is also reflected in the reproduction test with cadmium. EC50-values varied between 5.55 (95%-CI: 3.14 - 8.35) and 19.9 µg/L (95%-CI: 16.4 - 24.0) with a coefficient of variation of 35.1%. The effect concentrations for TBT and cadmium are in good accordance with already published data. Both pre-validation studies show that the reproduction test with P. antipodarum is a well suited tool to assess effects of EDCs and other chemicals. [1] OECD. 2010. Detailed review paper on molluscs life-cycle toxicity testing. ENV/JM/MONO(2010)9, Paris, France.