Effects of atrazine, diuron and glyphosate mixtures on zebrafish embryos: acute toxicity and oxidative stress responses.

Synthetic pesticides are known for their toxic effects on non-target aquatic organisms. However, little is known about their effects when present in mixtures, which are closer to realistic exposure scenarios. Therefore, this study evaluates the toxicity of pesticides such as diuron, atrazine and glyphosate, individually and in combination, in zebrafish embryos, investigating their mechanisms of oxidative stress. The results revealed acute toxicity for diuron and atrazine, with LC values of 9.6 mg/L and 53.57 mg/L for 96-h-old zebrafish, respectively. On the other hand, no effect was observed for glyphosate alone at the maximum concentration tested (100 mg/L). The mixture of diuron and atrazine showed a synergistic effect, resulting in a decrease in the LC of each pesticide. Mixtures of diuron + glyphosate and atrazine + glyphosate were considered additive and antagonistic, respectively. All biomarkers analyzed (AChE, LDH, GST, CAT and GPx) showed significant changes. Furthermore, an increase in ROS production was observed in larvae exposed to individual and in the mixture composed of atrazine and diuron. These findings indicate that atrazine and diuron exhibit increased toxicity when combined, with their mechanisms of action-both in isolation and in mixtures-being at least partially linked to oxidative stress.