Acute Toxicity, Bioaccumulation and Elimination Rate of Deltamethrin and Cypermethrin in Crucian Carp (Carassius auratus)

Pyrethroid pesticides like deltamethrin and cypermethrin are widely used in aquaculture, yet their food safety implications remain understudied. This research investigated their acute toxicity, tissue-specific bioaccumulation, and elimination patterns in crucian carp (<i>Carassius auratus</i>). Acute toxicity tests determined 96 h LC50 values of 9.68~11.22 ng·mL⁻¹ (deltamethrin) and 3.12~5.01 ng·mL⁻¹ (cypermethrin) with 95% confidence intervals. During 8-day exposures to sublethal concentrations (1/10 and 1/100 of LC50), deltamethrin accumulated predominantly in the liver (peak: 21.98 ng·g⁻¹ at 1.04 ng·mL⁻¹, standard deviation is 0.064 ng·mL⁻¹), whereas cypermethrin concentrated in muscle (peak: 9.76 ng·g⁻¹ at 0.40 ng·mL⁻¹, standard deviation is 0.138 ng·mL⁻¹). A 7-day elimination phase revealed faster clearance of low-concentration residues, with >50% removal within 24 h in all tissues. Bioconcentration factors were highest in the liver (36.62 for deltamethrin) and muscle (45.17 for cypermethrin). These results highlight tissue-specific accumulation risks and rapid initial elimination, providing critical data to optimize pesticide-dosing protocols, mitigate ecotoxicological threats, and enhance food safety in aquaculture systems.