Acute and short-term developmental toxicity of cyhalofop-butyl to zebrafish (Danio rerio)

Cyhalofop-butyl is an aryloxyphenoxypropionate post-emergence herbicide widely used around the world in agriculture. The acute toxicity of cyhalofop-butyl to embryos, larvae (12 and 72 h post-hatching), and adult zebrafish, as well as the short-term developmental toxicity of cyhalofop-butyl to embryo and sac-fry stages, was tested. The results showed that the 96-h LC50 values of cyhalofop-butyl to embryos, 12 h post-hatching larvae, 72 h post-hatching larvae, and adult fish were 2.03, 0.58, 1.42, and 3.49 mg/L, respectively, suggesting zebrafish early life stages were more sensitive to cyhalofop-butyl than adult stage. Cyhalofop-butyl would inhibit the spontaneous movement, heartbeat, hatching rate of embryos, and the body length of surviving larvae of zebrafish at 1.00 mg/L or higher concentrations. Morphological abnormalities, including pericardial edema, yolk sac edema, deformation of tail, and deformation of spine, were induced by cyhalofop-butyl. The results indicated that cyhalofop-butyl had significant negative impacts on zebrafish at different life stages, and spontaneous movement and hatching rate were sensitive endpoints for assessing short-term developmental toxicity of cyhalofop-butyl.