Optimizing Veterinary Drug Residue Monitoring in U.S. Cattle through Trend Analysis and Risk-Based Frameworks

Abstract

Veterinary drug residues in U.S. cattle continue to raise important food safety, regulatory, and public health concerns. This dissertation integrates three complementary investigations to examine residue trends, evaluate human health risks, and propose an improved framework for national monitoring. First, national sampling data from the USDA Food Safety and Inspection Service (FSIS) National Residue Program (NRP) for 2021–2023 were analyzed to identify frequently detected residues across cattle types. Cattle accounted for 92% of all positive samples across species sampled (sheep and goats, pigs, poultry, and fish), totaling 3,107 out of 3,391 detections. Dairy cows had the highest number of detections within cattle (1,264 out of 3,107). Desfuroylceftiofur, penicillin, flunixin, and several sulfonamides were among the most commonly detected violative residues. Second, a multifactorial risk-ranking model was developed to assess the potential public health risks associated with fifteen high-priority veterinary drugs detected in cattle. The model integrated hazard evidence, exposure frequency, and severity of adverse outcomes across eleven risk domains. Sulfonamides consistently ranked as the highest-risk group, while β-lactams and non-steroidal anti-inflammatory drugs (NSAIDs) ranked as intermediate-risk due to frequent detection despite moderate inherent toxicity. Finally, an adaptive decision support framework was created to improve veterinary drug residue monitoring by incorporating drug-specific, species-specific, and exposure-related determinants into a unified evaluation system. The framework provides clear thresholds for prioritizing high-risk drug species combinations and can support more efficient risk-based sampling strategies aligned with the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), as well as the Codex Alimentarius Commission. Collectively, these studies demonstrate the need for continuous monitoring of frequently detected residues, improved prioritization of high-risk analytes, and an adaptive, evidence-driven approach to sampling. The findings offer actionable recommendations to strengthen residue-control programs, enhance regulatory responsiveness, and protect public health.