Evaluation of Genotoxic and Mutagenic Effects of Glyphosate Roundup Original (R) in Dendropsophus minutus Peters, 1872 Tadpoles

The herbicide glyphosate is widely used on Brazilian crops and commonly found in water bodies. Despite its usefulness in controlling pests and increasing agricultural production, improper use of this environmental contaminant might accelerate the decline of species, especially frogs. The aim of this study was to evaluate the genotoxic and mutagenic effects of glyphosate Roundup Original (R) in tadpoles of Dendropsophus minutus by comet assay and micronucleus test. Fourteen egg masses were collected in two permanent ponds in Chapada dos Veadeiros National Park in Alto Paraiso de Goias, Brazil. Acute exposure was conducted with 180 tadpoles maintained for 99 d in a storage tank until developmental stages 26-31. During acclimation, tadpoles were distributed among 36 tanks and exposed to the following concentrations of the active ingredient (ai) glyphosate Roundup Original (R): 0.28 mg ai/L, 1.0 mg ai/L, 2.0 mg ai/L, 4.0 mg ai/L of, negative control (0 mg ai/L), and positive control (10 mg ai/L mitomycin C). After 96 h of exposure, the tadpoles were euthanizecl with 5% benzocaine and submitted to comet assay and micronucleus test. In the comet assay, a significant increase in DNA damage was observed in response to the 0.28 mg ai/L concentration for tail length, % DNA in the tail, and Olive tail moment. There was no dose-response effect at other concentrations. For the micronucleus test, we did not find a statistically significant increase in micronuclei in erythrocytes of D. minutus after 96 h of exposure to glyphosate. Therefore, in the present study we found that tadpoles of D. minutus are extremely sensitive to low concentrations of glyphosate, demonstrating the importance of amphibian tadpoles in studies of genotoxicity and mutagenicity.