A Mixture of Herbicides Dicamba and Glyphosate Causes Teratogenic Effects, Oxidative Stress, and Neurotoxicity in Zebrafish Embryos

Exposure to pesticides during embryonic development can cause damage to health, especially when they are complex mixtures. This study evaluated the lethality, teratogenic effects, antioxidant system, and neurotoxicity in zebrafish (Danio rerio) embryos during a 96 h exposure to the herbicides dicamba (DIC) and glyphosate (GLY), alone and in a mixture. The embryos were exposed to 18 (D1) and 72 (D2) mg/L of DIC, 6 (G1) and 22 (G2) mg/L of GLY, and mixtures M1 (18 mg/L of DIC + 6 mg/L of GLY) and M2 (72 mg/L of DIC + 22 mg/L of GLY). The LC50 was 88.1 mg/L and 285.8 mg/L for GLY and DIC, respectively. M2 showed greater lethality at 48 and 72 h. The mixtures increased teratogenic effects. Generalized edema, predominant in embryos exposed to DIC, reached its maximum incidence between 48 and 72 h and then decreased. M1 delayed hatching by 72 h, while M2 accelerated it by 48 h. Yolk sac edema was significant in M1. Herbicides affected the antioxidant system differently: DIC reduced SOD activity, while GLY increased it. Additionally, DIC and M2 increased acetylcholinesterase activity, indicating neurotoxicity. This is the first study to report the effects of these herbicide mixtures on zebrafish embryos, highlighting the complexity and severity of their impact on embryonic development. Therefore, the importance of the controlled use of these pesticides is emphasized to avoid harmful effects on non-target organisms.