Combined subacute toxicity of copper and antiparasitic albendazole to the earthworm (Eisenia fetida)

Copper (Cu) is one of the most common metal contaminants, and albendazole (ABZ) is a veterinary drug with a high efficacy against helminthes. It is believed that the two may co-exist in soil. In this study, the combined subacute toxicity of Cu exposure (0, 80, 120, 160 mg kg(-1)) and ABZ exposure (0, 3, 9 mg kg(-1)) in earthworms (Eisenia fetida) were observed using three approaches, namely chronic growth and reproduction, antioxidant enzyme activity, and earthworm Cu residue. The results have shown that the toxicity of Cu on cocoon hatching success and biomass was alleviated by presence of low concentrations of ABZ (3 mg kg(-1)) during a 56-day exposure period. However, the sensitivity of the earthworms' reproduction to Cu increased with the presence of high concentrations of ABZ (9 mg kg(-1)), indicating a reduction beginning at a Cu concentration of 80 mg kg(-1), in the cocoon number, hatching success, and biomass. In addition, the three enzyme activities exhibited different responsive patterns, indicating inducement in the catalase and glutathione peroxidase, and inhibition in the superoxide dismutase, which were dependent on the exposure times and concentrations. In regard to the earthworm Cu residue, when increasing Cu exposure concentrations, the internal Cu concentrations tended to level off, exhibited a linear pattern at the Cu concentration range of 40 to 120 mg kg(-1), and showed a stable trend above 120 mg kg(-1). The results of the present study can potentially provide important information regarding the combined toxicity of the veterinary drugs and the heavy metals in soil.