Picloram (PIC) is an herbicide widely used in Uruguay to control weeds, especially in forest crops. In the present study, we evaluate the acute toxicity and genotoxicity of formulated 24.9% PIC-based Tordon®24K on Boana pulchella tadpoles under standard laboratory conditions. In the acute toxicity test we use mortality as the endpoint and we obtained a 48-h LC50 of 16.5 mg/L, LOEC 14.5 mg/L, and NOEC 12.5 mg/L. We determined genotoxicity in GS36 tadpoles exposed to sublethal concentrations of 8.5 (NOEC/1.5) and 12.5 mg/L (NOEC) PIC using micronucleus frequency (MN) and occurrence of nuclear abnormalities (AN) as endpoints. We noticed a significant increase in the frequency of MN and AN in all treatments tested at sublethal concentrations. Our findings demonstrate the genotoxic effects of this herbicide, which represent a danger to amphibians that inhabit agroecosystems. Based on the results obtained and considering that Boana pulchella is not a threatened species and has a wide distribution in the Uruguayan territory and the Pampa Biome, it could be considered a reference organism in environmental monitoring programs in the region.
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