FABIANA DIAS LOPES
Abstract:
Brazil has been occupying a prominent position in agribusiness since 2008, considered one of the largest consumers of agrochemicals in the world. Among these, herbicides based on glyphosate (HGLY) have been the most used herbicides. H is able to inhibit the enzyme 5- enolpyruvoylshikimate-3-phosphate synthase (EPSPS), an enzyme present in plants, but absent in animals. 5-enolpyruvyl-xykimate-3-phosphate synthase (Gly) and RTR are quite toxic to animals, but some studies suggest that the toxicity is related to the surfactants, as well as the POEA-polyoxyethyleneamine present in the commercial formulation of RTR In this study we evaluated the toxic effect of the herbicide Gly, the POEA adjuvant and the RTR, through the acute exposure on D. rerio embryos. The embryos were exposed and evaluated in a 24-well plate for up to 96 hours observing their vital and developmental parameters through the Leica AZ microscope. The embryotoxic activity on D. rerio of the compounds (RTR, Gly and POEA) is of the concentration-time dependent type. The RTR was the most embryotoxic, presenting LC50 / 24h were 44.6 times higher than Gly and 6 times higher than POEA. All compounds led to changes in eye formation and presence of pericardial edema at concentrations chosen as sublethal; 3.75, 30 and 25 μg / mL, respectively, for RTR, Gly and POEA for up to 96 hours. Heart rate analysis (beats per minute - bpm) showed embryotoxicity for the compounds tested. Exposure to RTR showed a decrease of bpm at the 24 and 48 h times for the concentrations of 7.5 and 3.75 μg / mL. At 96 h the concentrations of 3.75 and 1.875 μg / mL were equally significant. Gly had an effect on bpms with difference only at 24 and 48h times, most evident at concentrations of 120 and 60 μg / mL. The POEA, unlike Gly, presented a change in bpm at 48 and 72 h for the concentrations of 50, 25 and 12.5 μg / mL. The morphological changes observed were pericardial edema, spinal curvature, which, with advancing exposure, especially in sub-lethal concentrations, intensified; and associations such as hatching delay and death arose. Finally, the results showed high toxicity of RTR compared to Gly and POEA and a great concern for human health, using the experimental model D. rerio.
