Avaliação da toxicidade dos herbicidas diuron, glifosato, atrazina e suas misturas em embriões e larvas de peixe-zebra (Danio rerio)

Abstract

This study aimed to assess the acute toxicity of the herbicides glyphosate, atrazine, and diuron individually and in binary and ternary mixtures on zebrafish embryos and larvae, exploring their mechanisms of oxidative stress. The results revealed relevant acute toxicity for diuron and atrazine, with LC50 values of 9.6 mg/L and 53.57 mg/L for 96-hour-old zebrafish, respectively. On the other hand, no effects were observed for glyphosate alone at the maximum tested concentration (100 mg/L). The binary mixture of diuron and atrazine exhibited a synergistic effect, resulting in the lowest measured LC50 values, 2.96 mg/L and 16.46 mg/L, respectively, among all combinations performed. In contrast to its lack of effects alone, glyphosate increased the individual toxicity of diuron and atrazine since a decrease in the LC50 values to 5.2 mg/L and 33.03 mg/L, respectively, although it was not considered synergistic. All analyzed biomarkers (AChE, LDH, GST, CAT, and GPx) showed significant alterations. Moreover, increased ROS production was observed in the larvae exposed to the individual herbicides and the mixture composed of atrazine and diuron. These findings showed that herbicides can become more toxic when present in mixtures and that their mechanism of toxicity, both in their isolated form and in mixtures, is at least partially associated with oxidative stress.