Assessment of the ecological risk posed by cypermethrin to surface waters based on a species sensitivity distribution model

Cypermethrin, as a type II pyrethroid broad-spectrum insecticide, is often detected in aquatic environments. However, the ecological risk posed by cypermethrin to global surface waters remains uncertain. In this study, the species sensitivity distribution and assessment factor-based methods were used to evaluate the sensitivity of various aquatic organisms to this insecticide, incorporating both acute toxicity and chronic toxicity data. Crustaceans exhibited the highest sensitivity to cypermethrin, whereas algae showed the lowest sensitivity. The acute and chronic hazardous concentrations of cypermethrin affecting 5 % of species (HC₅) in freshwater environments were determined to be 9.2 × 10⁻⁵ and 3.5 × 10⁻⁵ mg/L, respectively. Therefore, it was concluded that cypermethrin is highly toxic to freshwater organisms, in line with previous ecological risk assessments conducted in 12 countries worldwide. Limited data are available on the toxicity of cypermethrin to marine organisms. Existing data suggest a high ecological risk of cypermethrin in the north central coastal zone of Sinaloa, Mexico. Thus, cypermethrin may pose serious ecological risks to aquatic organisms globally and potentially threaten human health.