Ecological effect assessment by species sensitivity distribution for 38 pesticides with various modes of action

Species sensitivity distributions (SSDs) of 38 pesticides with various modes of action were analyzed as a higher-tier ecological effect assessment based on collected acute toxicity data. Then the 5% hazardous concentrations (HC(5)) based on each SSD were calculated as the predicted no-effect concentrations for aquatic ecosystems. The differences between HC(5) and registration criteria were small (within ten-fold) for 35 of the 38 pesticides. However, there were more than ten-fold differences for a fungicide and two herbicides. These results suggest that the current effect assessment scheme could underestimate the effect of such pesticides. This could be caused by differences in sensitivity of specific properties of the mode of action.