Estudo da embriotoxicidade e morfometria larval em zebrafish (Danio rerio) após exposição à uma formulação comercial contendo o herbicida metribuzin

Abstract

Pesticides are used worldwide to improve crop productivity by eliminating insect vectors of diseases or weeds (pests) from agricultural crops. Brazil is one of the largest consumers of pesticides in the world. However, these compounds can cause negative impacts on the environment and human health. Metribuzin is a herbicide from the chemical group of asymmetric triazinones, with a broad spectrum of action that acts by inhibiting photosynthesis. Used mainly in sugarcane, tomato and soybean crops, it is potentially toxic and considered dangerous for the environment, as it has a high solubility rate in water (1.22 mg/L) and a half-life of approximately seven days in water and 30 days in the soil, making it possible to contaminate the soil, surface and underground waters and the organisms present, through leaching from agricultural fields. It is already known that metribuzin and other herbicides of the same chemical group are toxic to some species of fish, causing loss of movement and coordination, increased breathing and biochemical, hematological and histopathological changes in fish tissues. However, the toxic effects of metribuzin in the early stages of development in fish have yet to be clarified. Therefore, in the present work, using zebrafish (Danio rerio) as a model species, the objective was to determine the embryotoxicity and possible morphometric changes in body development after exposure to different concentrations of the herbicide based on metribuzin (UNIMARK 700 WG). Zebrafish embryos/larvae were exposed to compound concentrations, previously diluted from the stock solution (0.0002 mg/mL, 0.002 mg/mL, 0.02 mg/mL, 0.1 mg/mL, 0.2 mg/mL, 0.4 mg/mL), negative control (reconstituted water) and DCA positive (Dichloroniline 3.4) for 144 hours. Afterwards, destined to the evaluation every 24 hours, of the spontaneous movement (24h), heartbeat (48h), mortality, hatching and morphological alterations evaluated in (24, 48, 72, 96, 120 and 144h) of exposure. The results of the present study indicated toxicity of the compound over the 144 hours concentration-dependent, with a high mortality rate at higher concentrations, tachycardia, morphological changes (with a higher frequency of deformations in the spine) and a decrease in hatching and spontaneous movements. The data obtained show the toxicity of the compound in the embryolarval stages and point to the need for further studies, including histological and behavioral ones, for greater knowledge about alterations and possible damages in other systems and different organisms.