Chemical Hazard in Bird Species

Abstract

　Nowadays, chemical hazards in bird have been reported worldwide, and above all, anticoagulant rodenticides for vertebrate pest control has frequently led to the unintentional exposures of non-target animals, especially birds. Several bird species, such as raptors, are suggested to be sensitive to anticoagulant rodenticides, however, the mechanism for this sensitivity has not yet been revealed. In wild rats, two causes are supposed to be possible reasons to explain the mechanism of rodenticide resistance; mutation of vitamin K epoxide reductase (VKOR) gene and acceleration in cytochrome P450-dependent detoxification. In case of wild birds, we reported that some of raptors have very low CYP-dependent warfarin metabolic activity relative to other avian species. In addition, we also showed Ki (inhibitory constant) for VKOR activity after warfarin treatment was 17- to 40-fold lower in ostriches or rats than in chickens. These facts were the first to indicate high warfarin resistance of chickens, and species difference in rodenticide sensitivity among birds.