The potential acute and chronic toxicity of cyfluthrin on the soil model organism, Eisenia fetida

- The reproductive toxicity of cyfluthrin in soil was demonstrated.
- The EROD activity in earthworms was induced significantly by cyfluthrin in soil after 3 days.
- The POD activity of earthworms was stimulated by cyfluthrin in soil under short-term exposure.
- The toxicity responses of earthworms to the degraded cyfluthrin demonstrated the possible formation of toxic metabolites.

In this study, the acute (72 h and 14 d) and chronic (28 d and 8 weeks) effects of cyfluthrin on earthworms were evaluated across different endpoints, which are mortality, growth, reproduction and enzyme activities. Cyfluthrin was rated as moderately toxic in 72-h filter paper test and low toxic in 14-day soil test. The exposure of earthworms to cyfluthrin-polluted soil for 8 weeks showed that growth of earthworms was inhibited by cyfluthrin, cocoon production and hatching were inhibited by 20-60 mg/kg cyfluthrin. Moreover, 28-day soil test on the responses of enzymes associated with antioxidation and detoxification showed that the activities of catalase (CAT) and glutathione S- transferase (GST) were initially increased by cyfluthrin at 5-20 mg/kg, but reduced at 30-60 mg/kg, peroxidase (POD) was increased by 26-102% by cyfluthrin in the early period, except 5 mg/kg on day 7, and ethoxyresorufin-O-deethylase (EROD) was increased by 29-335% by cyfluthrin after 3 days. Cyfluthrin degraded with a half-life of 24.8-34.8 d, showing the inconsistency between the continuous toxic responses of earthworms and degradation of cyfluthrin in soil. The variable responses of these indexes indicated that different level endpoints should be jointly considered for better evaluation of the environmental risk of contaminants in soil.