Genotoxicity, mutagenicity and immunotoxicity assessment of microplastics and nanoparticle mixture in bullfrog tadpoles

Abstract

Amphibians are among the most endangered vertebrates whose population declines are linked to environmental pollution, including emerging pollutants such as microplastics (MPs) and nanoparticles (NPs). However, knowledge about the interactive effects of MPs and titanium dioxide (TiO2) NPs on amphibians remain scarce. This study aimed to evaluate the potential genotoxicity, mutagenicity and immunotoxicity of polyethylene (PE) MPs (60 mg L−1) and TiO2 NPs (10 μg L−1), individually or in a mixture (Mix) in Aquarana catesbeiana tadpoles, Gosner stage 25, after a sub-chronic exposure (15 days). Multiple parameters were assessed by the comet assay, micronucleus test and nuclear abnormalities in erythrocytes, and differential leukocyte count. The individual pollutants and the Mix did not cause genotoxicity. The total number of nuclear abnormalities, the frequency of notched nucleus and moved nucleus were higher in individually PE MPs and TiO2 NPs groups, but not in Mix. Both pollutants, individually and in a mixture, did not alter the leukocyte profile of the tadpoles. Overall, our results reinforce the complexity of the outcomes of emerging pollutant mixtures, which represent a new environmental issue to discuss about amphibians' health and ecotoxicology.