Dietary Exposure Assessment of Veterinary Drug Residues in Animal-Derived Foods: Results from the Sixth Chinese Total Diet Study

The global emergence of antibiotic residues in food-producing animals has raised substantial public health concerns due to their accumulation in edible tissues and organs. This investigation, conducted under the Sixth Chinese Total Diet Study (TDS), utilized ultra-high-performance liquid chromatography–high-resolution mass spectrometry to examine 96 composite dietary samples (derived from 1461 commonly consumed items) for the presence of 25 veterinary drugs (VDs) spanning seven therapeutic categories. The overall detection rate was 22.0%, with eggs (30.3%) and meats (30.0%) showing the highest rates. Four regulated VDs (trimethoprim, ofloxacin, enrofloxacin, and sarafloxacin), total sulfonamides, and three prohibited VDs (metronidazole, metronidazole, and chloramphenicol) in 22 samples (22.9%) exceeded the maximum residue limit (MRL) in China. These MRL comparisons are for reference only, as the MRL applicable to raw tissues does not match the cooked food composite samples analyzed in this study. Descriptive comparison across the Fourth to Sixth TDSs showed numerical differences in quinolone and sulfonamide detection rates and concentrations, though these findings require cautious interpretation due to methodological differences. For prohibited VDs lacking acceptable daily intakes (ADIs), the threshold of toxicological concern screening indicated that metronidazole and dimetridazole exceeded the genotoxic threshold, suggesting the need for further evaluation and attention. Notably, despite the high enrofloxacin occurrences (100% in aquatic products, 79.2% in meat samples), the estimated daily intakes for authorized VDs remained below 10% of their ADIs, indicating low health risks under the current exposure conditions.