Assessment of Cerium-oxide (CeO2) nanoparticle ecotoxicity using non-biting midge Chironomus riparius (Diptera, Chironomidae)

Abstract

The toxicity of Cerium-oxide nanoparticles (nano-CeO2) on freshwater midge Chironomus riparius, Meigen, was assessed by observing several biomarkers. The experiments were designed using measured concentrations of nano-CeO2 in the sediment, according to the OECD guidelines for testing of chemicals, in the laboratory setup. The full characterization of the CeO2 nanoparticles was made and the concentrations of 2.5, 25, 250 and 2500 mg of nano-CeO2 per kg of sediment were tested. The increase of nano-CeO2 content in the chironomid larvae was observed when its content was increased in the sediments (Spearman rho test rho=0.73, p<0.01). The toxicity was not detected at the developmental level, causing no observable effects on life traits. At the lower biological level, toxicity was detected through significant DNA damage in the midges exposed to higher nano-CeO2 levels (one-way ANOVA p < 0.05). In addition, investigated oxidative stress parameters showed no significant differences between the treatments. There is a need for further investigation in order to understand causal relationships between molecular and higher-level responses to nano-CeO2 exposure. Nevertheless, obtained results indicate that C. riparius could be used as bioindicator, providing valuable information for nano-CeO2 risk assessment freshwaters and environmental protection planning