Dietary intake estimates as a means to the harmonization of maximum residue levels for veterinary drugs. I. Concept.

The harmonization of standards and procedures for establishing tolerances or maximum residue levels (MRLs) for veterinary drug residues in edible animal products is a major goal of the international veterinary drug community. Such harmonization would contribute to easing trade barriers. This paper proposes use of the toxicologically determined acceptable daily intake (ADI) for the drug as the safety standard for reaching conclusions on the acceptability of residues in meat for human consumption. Specifically, the 'equivalence' of different MRLs for the same veterinary drug would be determined by considering whether they are likely to result in dietary residues that exceed another country's ADI for the drug. Two methods of estimating dietary intake are described, and estimates are made for the veterinary drugs albendazole and ivermectin. Based on these estimates, the US and JECFA MRLs for each drug would be considered 'equivalent' for trade purposes.