Piscine micronucleus test and the comet assay reveal genotoxic effects of Atrazine herbicide in the neotropical fish Rhamdia quelen

Atrazine (ATZ) is an herbicide extensively used around the world to kill weeds. Due to its applicability and benefits in farming, ATZ can easily reach the aquatic ecosystems and, therefore, represent risks for aquatic biota and human populations. The aim of this study was to evaluate the genotoxic effects of ATZ on Rhamdia quelen through the piscine micronucleus test (MNT) and the comet assay in erythrocytes (ECA) and gill cells (GCA), at three different concentrations (2, 10, and 100 μg L-1) in static (SB) and semi-static bioassays (SSB) during 96 hours. In the SB, we observed an increased frequency of nuclear morphological abnormalities at all concentrations and a dose-dependent effect of ATZ on DNA through the ECA. There was no difference among treatments in gills. In the SSB there was no significant difference in MNT, but the ECA showed an increase of DNA breakages at 10 μg L-1 treatment. GCA showed higher DNA damage on fish exposed to 2 and 100 μg L-1. Our results show a trend to dose-dependent genotoxic effect of ATZ, which causes damage to the DNA of Rhamdia quelen even in a concentration considered safe by regulatory agencies.