Use of a fast toxicity test to determine whether carbendazim, fipronil, and sulfentrazone and their mixtures affect early zebrafish embryonic development

Abstract

Because of the exacerbated use of pesticides and their mixtures, and the difficulty of evaluating their toxicity, it is necessary to identify sensitive tools for the early detection of potential environmental risks related to the use of these chemicals. Our objective was therefore to evaluate the effects of these chemicals using a rapid 24 h toxicity test in zebrafish embryos. After exposure of individual and mixtures of the pesticides carbendazim (carb), fipronil (fipr), and sulfentrazone (sulf), the lethality and sublethally at 24 hpf, the effects of the mixtures on epiboly and on coagulation of the embryos at 8 hpf were evaluated. This model can be extrapolated to several vertebrate groups, including humans. All three pesticides were toxic in both exposure periods, at 24 hpf, all concentrations used affected the embryos, with lethal and sublethal effects occurring. At 8 hpf, epiboly analysis indicated that the mixtures did not potentiate the effects compared to the pesticides alone, being toxic in the order: carb > sulf > fipr > fipr + sulf > carb + sulf > carb + fipr + sulf > carb + fipr + sulf > carb + fipr. We conclude that the most toxic pesticide was sulfentrazone, since it was highly toxic to embryonic development at 24 hpf and caused both delayed epiboly and high percent clotting at 8 hpf. Thus, we see that the rapid toxicity test was effective in assessing the toxicity of pesticides and was sensitive in assessing the effects of pesticides at low concentrations.

Keywords: epiboly, pesticides, teratogenicity.