Genotoxic and mutagenic effects of zinc oxide nanoparticles and zinc chloride on tadpoles of Lithobates catesbeianus (Anura: Ranidae)

Abstract

The growing production and use of nanomaterials raised concerns about their release and impact on aquatic ecosystems. However, knowledge about nanoecotoxicity to amphibians is still limited. In this sense, this is the first study that analyzed the genotoxic and mutagenic effects of zinc oxide nanoparticles (ZnO NPs) and their dissolved equivalent (ZnCl2) in Lithobates catesbeianus (Shaw, 1802). The tadpoles were exposed to different concentrations of ZnO NPs and ZnCl2 (0.1, 1.0, and 10 mg L−1) for 7 days. Genotoxicity was analyzed in erythrocytes by comet assay, while mutagenicity was assessed by micronucleus test and erythrocyte nuclear abnormalities. Tadpoles of L. catesbeianus exposed to ZnO NPs at 0.1, 1.0 mg, and 10 mg−1 showed significant DNA damage compared to the control group. Besides, acute exposure to both Zn forms at 10 mg L−1 induced a higher frequency of erythrocytes with micronucleus and anucleated cells compared to control group, indicating the potential genotoxic and mutagenic effects of ZnO NPs for amphibians. Therefore, using agriculture as an activity responsible for the environmental contamination (from fertilizers and pesticides) particularly by the metals like Cd, Cr, Cu, Pb, Mn, and Zn affecting the water bodies, many studies have been published with this intent. It is clear how much the usage of CA and MN is important and useful to evaluate the genotoxicity and mutagenicity in many aquatic organism groups, including anurans.