Limit-test toxicity screening of selected inorganic nanoparticles to the earthworm Eisenia fetida

The toxicity of a range of inorganic (Ag, Cu, Ni, Al₂O₃, SiO₂, TiO₂ and ZrO₂) nanoparticles (NP) and their corresponding metal salt or bulk metal oxide were screened for toxicity toward the earthworm Eisenia fetida using the limit-test design (1000 mg/kg). This study provides the first ecotoxicological life history trait data on earthworms for each these NPs, as well as for AgNO₃, Al₂O₃, SiO₂, TiO₂ and ZrO₂. Significant effects were observed on survival for AgNO₃ (2.5% of controls), CuCl₂ (17.5% of controls) and NiCl₂ (32.5% of controls) and on reproduction (AgNO₃, CuCl₂, NiCl₂, Ag-NP, Cu-NP, TiO₂-NP); with total reproductive failure in both silver treatments. Ag-NP, Cu-NP and TiO₂-NP were the only NPs that caused toxic effects to E. fetida. The toxicity could not be singularly related to particle size or zeta potential or to the inherent element constituting the NPs (e.g. Ag).