LAUSR

T Food Animal Residue Avoidance Databank (also known as the Food Animal Residue Avoidance and Depletion Program; FARAD) frequently receives requests for withdrawal interval (WDI) recommendations following inadvertent exposure of food animals to various environmental contaminants and pesticides such as rodenticides (Table 1). Rodenticide exposure in food animals typically occurs as a result of widespread use on farms for rodent control, contamination of waterways, or malicious intent. The Environmental Protection Agency (EPA) is the regulatory body that oversees rodenticides in the US, with 11 rodenticide chemicals currently carrying numerous active commercially registered products. The principal challenges when recommended WDIs are formulated for animals exposed to anticoagulant rodenticides and rodenticides with other mechanisms of action are numerous. These challenges include a lack of robust tissue pharmacokinetic data (particularly limited tissue half-lives) in many species, the low number of animal subjects enrolled in pharmacokinetic studies that may not represent population variations, and incomplete knowledge of dose exposure in affected animals. For most rodenticides, marker residues can be present in tissues such as the liver, pancreas, and kidney for years following oral exposure, whereas other more commonly consumed tissues may have declining residues over a period of months. Therefore, despite clinical resolution of rodenticide toxicosis in affected animals, extremely Mechanisms of toxicity and residue considerations of rodenticide exposure in food Animals—a FARAD perspective