Efeitos tóxicos de concentrações ambientalmente relevantes dos herbicidas 2,4-D e imazetapir em girinos de physalaemus cuvieri

Abstract

The presence of pesticide residues in aquatic environments is of concern due to the possibility of causing adverse effects on aquatic biota. Brazil is one of the largest consumers of pesticides in the world due to its agricultural and food production potential and due to this, pesticide residues can reach amphibian habitats and cause harmful effects to these organisms. Among pesticides, the herbicides 2,4-D and imazethapyr stand out for their wide use. Therefore, the objective of this work was to evaluate the sublethal toxicity of a commercial formulation of 2,4-D and imazethapyr in Physalaemus cuvieri tadpoles. For both herbicides, tadpoles were exposed for 14 days to environmentally relevant concentrations. Animals were exposed to 0, 1, 7, 21, 35 and 50 μg/L of 2,4-D and 0, 1, 13, 57, 100, 200, 300 and 400 μg/L of Imazetapyr. Survival and swimming activity were monitored throughout the experimental period. Growth parameters were measured at the beginning and end of the experiment. At the end of the test, the tadpoles were observed for the occurrence of morphological abnormalities in the mouth, intestine, tail and blood smears were also taken to evaluate the genotoxic potential of the herbicides. Furthermore, the ecological risk coefficient was calculated in order to determine the potential risk of these two hebicides to non-target species. Tadpoles exposed to the two herbicides showed weight loss, changes in the mouth and intestine, as well as erythrocyte nuclear and micronucleus changes. Neither compound caused morphological changes or changes in the swimming activity of the animals, however, both herbicides caused genotoxicity and chronic risk to P. cuvieri tadpoles. Therefore, it is concluded that the formulations studied present sublethal toxicity and cytogenotoxicity at concentrations that can occur in nature and affect the health of P. cuvieri.