Co-occurrence of pyrethroids and heavy metals in aquatic ecosystem arouses particular concern over their combined ecological effects. However, little information so far is available regarding their joint effects on aquatic species like fish. In this study, combined toxicity of cypermethrin (CP) and cadmium (Cd) to zebrafish and the underlying mechanism were investigated. Embryos were exposed to individuals and the binary mixtures from 3 h postfertilization (hpf) to 144 hpf. Exposure to the mixtures of CP and Cd produced synergistic effects on occurrence of developmental defects including crooked body, pericardial edema and swimbladder non-inflation. The addition of Cd potentiated CP-induced spastic response in the embryos. The addition of Cd to CP-exposed groups also caused more oxidative stress in zebrafish embryo. The transcription levels and catalytic activities of cytochrome P450 (CYP) enzymes, which are responsible for CP detoxification in zebrafish, were significantly down-regulated by the mixture. We further showed that the addition of Cd inhibited CYP1A1-mediated metabolism of CP and elevated CP residue levels in the mixture-exposed animals. These results suggest that the enhanced toxicity of cypermethrin to fish might result from the inhibitory effects of Cd on the CYP-mediated biotransformation of this pesticide. Our findings provide a novel insight into the underlying mechanism responsible for joint toxicity of pyrethroids and heavy metals.

Cadmium potentiates pyrethroid pesticide cypermethrin toxicity in zebrafish

248th National Meeting (2014)

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