Veterinary drug residues in meat, milk, eggs, fish, and honey remain a persistent and complex food safety problem, according to a review published in the journal Food Safety and Risk on 14 May 2026. The article, written by Muhammad Yasir Alhassan and Sumayya Alhassan Abdullahi, synthesizes evidence spanning pharmacokinetics, food processing chemistry, analytical detection, and international regulation to argue that current surveillance systems systematically underestimate real consumer exposure. The authors identify three interacting drivers: biological variability in how different animal species handle drugs, non-compliance with withdrawal periods on farms, and inadequate laboratory infrastructure, particularly in low- and middle-income countries.
The review classifies veterinary drug residues as a One Health challenge, meaning the problem connects animal health, human health, and environmental sustainability. Antimicrobials, anthelmintics, non-steroidal anti-inflammatory drugs, and hormonal agents are the principal residue classes of concern. When these compounds exceed established maximum residue limits, they may trigger allergic reactions, endocrine disruption, and mutagenic or carcinogenic effects, and they contribute to the accelerating global crisis of antimicrobial resistance. Even sub-therapeutic concentrations can exert selective pressure on microbial populations, promoting resistant strains that circulate among humans, animals, and the environment.
Pharmacokinetic variability across species, tissues, and physiological states is a central determinant of residue persistence. Differences in absorption, distribution, metabolism, and excretion mean that identical doses can produce markedly different tissue concentrations in different animals. Tetracyclines and macrolides bind strongly to tissues because of their lipophilicity and protein affinity, prolonging persistence in adipose tissue relative to plasma or muscle. The metabolism of beta-lactam antibiotics and sulfonamides depends on cytochrome P450 pathways that vary among species and are influenced by age, nutritional status, and physiological stress. Anthelmintics such as ivermectin and albendazole persist in ruminant tissues because of lipophilicity and depot effects, resulting in extended elimination periods.
Farm management practices compound these biological factors. Off-label administration and prophylactic drug use remain prevalent in production systems with limited veterinary oversight, particularly in resource-constrained settings. Inaccurate body weight estimation, incomplete treatment regimens, and non-adherence to withdrawal periods increase the probability that residues will persist at slaughter or during milk and egg collection. Continuous secretory matrices such as milk and eggs facilitate transfer of systemically circulating compounds, while aquaculture species may accumulate residues from medicated feed and waterborne exposure. These production-level determinants interact with pharmacokinetic variability to shape final residue concentrations in food.
A distinctive contribution of the review is its treatment of food processing, which the authors argue is rarely incorporated into surveillance strategies or maximum residue limit determinations. Thermal treatments, fermentation, and storage can modify drug stability, generate degradation products, and alter toxicological profiles. Beta-lactam antibiotics show pronounced heat lability, with significant degradation reported at temperatures exceeding 100 degrees Celsius, primarily through opening of the beta-lactam ring. Tetracyclines undergo epimerization and dehydration during heating, producing 4-epimers and anhydro derivatives that may retain partial antimicrobial activity. Sulfonamides are comparatively thermostable but degrade under elevated temperatures through bond cleavage pathways that modify antimicrobial efficacy.
The stability of other drug classes varies considerably. Enrofloxacin shows limited degradation under conventional cooking conditions but may undergo oxidative transformation under prolonged or high-temperature exposure. Macrolides such as tylosin exhibit moderate thermal stability yet remain susceptible to acid-catalyzed degradation in processed foods with reduced pH. Lipophilic antiparasitic agents including ivermectin persist during cooking because they are sequestered within lipid-rich matrices, demonstrating that degradation is compound-specific and matrix-dependent. For sulfonamides and tetracyclines specifically, the formation of bioactive degradation products during thermal processing means that apparent reductions in parent compound concentration do not necessarily correspond to elimination of biological risk. Non-steroidal anti-inflammatory drugs such as diclofenac and flunixin are expected to be more heat-stable than many beta-lactams, but extended heating can still cause partial breakdown of their active structures, and there is currently little peer-reviewed, systematic evidence on how NSAID residues are depleted or transformed during processed meat production, especially at the class level.
Fermentation introduces distinct biochemical pathways that influence residue fate. Lactic acid bacteria employed in dairy and meat fermentations can reduce concentrations of selected antimicrobials through metabolic and enzymatic processes. Acidification during fermentation accelerates degradation of certain beta-lactams, whereas the stability of other compounds varies according to pH-dependent solubility and binding characteristics. Partitioning behavior during cheese production results in preferential distribution of lipophilic drugs within curd fractions, while more hydrophilic compounds are more readily transferred to whey. Such redistribution alters residue profiles in final products relative to raw milk. Refrigeration and freezing generally slow chemical reactions and prolong stability of many veterinary drugs, though gradual degradation of tetracyclines and sulfonamides during extended frozen storage has been reported, and light exposure can accelerate photodegradation of fluoroquinolones and tetracyclines.
On the analytical side, the review draws a sharp line between established regulatory methods and emerging technologies. Liquid chromatography coupled with tandem mass spectrometry remains the internationally recognized confirmatory method for multi-residue analysis, offering high specificity, reproducibility, and sensitivity at the nanogram-per-kilogram level across diverse drug classes and food matrices. Enzyme-linked immunosorbent assays and other immunochemical methods represent the most widely deployed commercial screening tools, being relatively inexpensive and capable of processing large sample batches efficiently. Lateral flow immunoassays permit qualitative or semi-quantitative detection of antibiotics and antiparasitic residues in milk, meat, and fish within minutes, with typical detection limits ranging from 1 to 10 micrograms per kilogram for major antibiotic classes, adequate for initial screening but requiring LC-MS/MS confirmation for regulatory enforcement decisions.
Emerging tools including CRISPR-Cas biosensors, nanomaterial-based electrochemical assays, and artificial intelligence-assisted spectroscopic systems show promise but remain largely at the proof-of-concept or research stage and are not yet routinely applicable in regulatory enforcement. The authors emphasize that none of the biosensor categories they describe is currently validated for routine regulatory use, and that without regulatory-grade validation data, inter-laboratory performance standards, and internationally accepted protocols, these platforms cannot be incorporated into enforceable surveillance schemes regardless of resource level. For countries with limited laboratory infrastructure, the review concludes that investment in strengthening ELISA and LC-MS/MS capacity, alongside training programs and regional laboratory networks, remains the most credible and impactful strategy for improving residue surveillance in the short to medium term.
The review also documents significant regulatory fragmentation. Maximum residue limits are derived from structured toxicological risk assessment procedures beginning with estimation of the Acceptable Daily Intake and the Acute Reference Dose, but implementation differs among regulatory authorities. The Codex Alimentarius Commission provides internationally recognized reference standards, the European Union applies a precaution-oriented approach with zero tolerance policies for genotoxic compounds such as chloramphenicol and nitrofurans, and the United States operates a tolerance-based system administered by the Food and Drug Administration and the Department of Agriculture. Tetracyclines illustrate the divergence: the European Union applies a stricter limit of 100 micrograms per kilogram in bovine muscle compared with the 200 micrograms per kilogram permitted under Codex, United States, and Chinese frameworks. These discrepancies generate trade disputes and rejection of consignments that satisfy one regulatory framework but not another, creating financial losses and reputational damage for exporters, with disproportionate burdens on low- and middle-income countries that depend on livestock and aquaculture exports. The authors argue that integrating processing-adjusted exposure data, harmonizing maximum residue limit policies across jurisdictions, and strengthening analytical capacity in resource-limited settings are essential for equitable food safety governance and sustainable animal production systems.
Subject of Research: Veterinary drug residues in animal-derived foods and their detection, processing transformations, and global regulation
Article Title: Veterinary drug residues in animal-derived foods: linking pharmacokinetics, processing transformations, and detection to global food safety governance
Article References: Alhassan, M. Y., & Abdullahi, S. A. (2026). Veterinary drug residues in animal-derived foods: linking pharmacokinetics, processing transformations, and detection to global food safety governance. Food Safety and Risk, 13(1), Article 22. https://doi.org/10.1186/s40550-026-00151-3
Image Credits: AI Generated
DOI: 10.1186/s40550-026-00151-3
Keywords: veterinary drug residues, food safety, maximum residue limits, antimicrobial resistance, LC-MS/MS, food processing, pharmacokinetics, One Health, biosensors, ELISA, low- and middle-income countries, regulatory harmonization
News Source: Kristina Jarvis. (October 30, 2026). Drug Residues Linger in Cooked Meat and Milk, Review Warns. Scienmag.
