Chronic effects of TiO2 and ZnO nanoparticles to earthworm Eisenia fetida

The present study focuses on the effects of TiO2 and ZnO nanoparticles to the earthworm, Eisenia fetida. Upon 48 h of exposure of earthworms to TiO2/ ZnO nanoparticles in filter paper (0.1, 1, 10, 100, 500, 1000 mg L-1), no acute toxicity was evidenced. Two soil types (sandy loam soil and clay loam soil) with different characteristics were used in the chronic toxicity study. Following 28 days of exposure to soils amended with TiO2 and ZnO nanoparticles (0.1, 1, 10, 100, 500, 1000 mg Kg-1), no significant chronic toxic effects on earthworms were observed in terms of survival, growth, and bioaccumulation. Reproduction of earthworms was only affected at the high concentrations of nanoparticles. TiO2 nanoparticles (1000 mg Kg-1) in sandy loam soil and ZnO nanoparticles (500 and 1000 mg Kg-1) in clay loam soil caused reproductive toxicity in earthworms. Our findings show that both nanoTiO2 and nano ZnO in the soil are likely to cause reproductive toxicity to earthworms at high dosages. More research on the fate and bioavailability of nanoparticles in the soil is required to understand the differences between different soils.