Embryotoxicity of Cypermethrin, a Synthetic Pyrethroid Insecticide in Zebrafish

Aim/Background: This study aimed to assess the toxicity of cypermethrin using zebrafish embryos as a model organism. Cypermethrin, a synthetic pyrethroid commonly used in agriculture and pest control, poses significant environmental risks due to its persistence and potential harm to aquatic organisms. Materials and Methods: Zebrafish embryos were exposed to varying concentrations of cypermethrin and both lethal and sublethal endpoints were monitored at 24, 48, 72 and 96 hr post-fertilization. Standardized protocols for the Fish Embryo Toxicity Test (FET) were followed to evaluate the effects of cypermethrin on zebrafish embryos. Results: The study found that cypermethrin exhibited concentration-dependent toxicity, with a calculated LC₅₀ (concentration causing 50% mortality) ranging from 43.75 μg/mL at 24 hr post-fertilization to 8.31 μg/mL at 96 hr post-fertilization. Lethal endpoints such as coagulation, lack of heartbeat, and lack of somite formation were observed, along with sublethal effects such as tail deformation and pigmentation abnormalities. Conclusion: The findings indicate that cypermethrin is highly toxic to zebrafish embryos, with mortality increasing over time and with higher concentrations. The study underscores the importance of using alternative models like zebrafish embryos for toxicity assessments, providing valuable insights into the environmental risks associated with synthetic pyrethroids like cypermethrin. Further research is warranted to explore the long-term effects and mechanisms of toxicity and to validate the sensitivity of zebrafish embryos as a model for assessing pesticide toxicity.