Zinc Phosphide Residues In Voles: Scenarios Showing Low Risks To Domestic Cats And Dogs

Authors

Ray T. Sterner, U.S. Department of AgricultureFollow

Date of this Version

1996

Document Type

Article

Citation

Published in Proceedings: Seventeenth Vertebrate Pest Conference … 1996, ed. Robert M. Timm & A. Charles Crabb (University of California, Davis, 1996).

Comments

Copyright © 1996 (where applicable) by the Vertebrate Pest Council of the Vertebrate Pest Conference. Used by permission.

Abstract

Zinc phosphide (Zn₃P₂, CAS #1314-84-7) is an acute rodenticide having numerous agricultural applications. This paper estimates the risk of mortality posed to domestic cats (Felis domesticus) and dogs (Canis familiaris) from ingestion of voles (Microtus spp.) that succumb to 2.0% Zn₃P₂ baits. Following a brief review of direct/indirect studies and incident reports relevant to nontarget-Zn₃P₂ effects and vole control, four scenarios of volecarcass ingestions needed for light and heavy cat and dog predators/scavengers to receive approximate lethal doses (ALDs = 40 mg/kg) of undigested rodenticide are described. Scenarios were derived using values reported by Sterner and Mauldin (1995) as the maximum 8.2 mg Zn₃P₂ ingested (ad libitum) and average 1.7 mg Zn₃P₂ whole-carcass residue. Extrapolating these "worst-case" loads to 2 and 6 kg cats and 1 and 36 kg dogs showed that between 5 and 847 Zn₃P₂-baited vole carcasses must be consumed in fairly rapid succession for these non-targets to ingest cumulative ALDs. The likelihood that even light (≤ 1-2 kg) cats and dogs will find and rapidly (≤24 h) ingest multiple (≥5) Zn₃P₂-dosed vole carcasses under registered applications seems remote.