Tolylfluanid induces developmental toxicity via liver dysfunction in zebrafish embryos

Background: Tolylfluanid is a phenylsulfamide fungicide used to mitigate enormous losses in agriculture and coastal industries. Previous studies have reported that exposure to tolylfluanid causes metabolic dysfunction, such as fat accumulation. Additionally, exposure to tolylfluanid used to be detected in strawberries at levels exceeding the maximum residue limit. However, no studies on early developmental toxicity in zebrafish models have been reported. Objectives: This study aimed to investigate the toxic effects of tolylfluanid on the early stages of zebrafish development. Results: At low tolylfluanid concentrations, survival rates, hatching rates, and yolk sac morphology remained unchanged. However, body length and eye size were slightly reduced compared to those of the control. In particular, olig2 transgenic zebrafish exposed to tolylfluanid exhibited impaired motor neuron formation, leading to reduced motor neuron length. Furthermore, tolylfluanid decreased liver size in fabp10a transgenic zebrafish larvae, inducing liver-specific red fluorescence. However, tolylfluanid exposure did not affect the vasculature of zebrafish embryos in the fli1a:eGFP transgenic model. Conclusion: Tolylfluanid disrupts organogenesis, particularly in motor neurons and the liver, during early development in zebrafish. Additionally, the results provide reference points for the concentration conditions that can be used in aquatic ecosystems.