Proposal for a tiered approach to developmental toxicity testing for veterinary pharmaceutical products for food-producing animals.

In order to establish the safety of veterinary drug residues in human food, a number of toxicological evaluations are required, including the assessment of potential risks to development. In the light of the use of developmental toxicity testing for risk characterization, we evaluated whether conducting these tests in more than one species was redundant. Review of the published Summary Reports of recommendations of the EU Committee for Veterinary Medicinal Products supplemented with data from the Joint FAO/WHO Expert Committee on Food Additives (JECFA) reports on veterinary drug residues in food identified 120 compounds, of which 105 had teratogenicity information in more than one species. The analysis of these compounds, representing a variety of chemical and pharmacological classes, provided justification for consideration of the use of a tiered approach for developmental toxicity evaluation of veterinary drugs for food-producing animals. The tiered approach begins with developmental toxicity testing in a rodent species, preferably the rat. If teratogenicity is observed, no testing in a second species would be required, except under specific circumstances where the ADI is determined based on the NOEL from this study. If a negative or an equivocal result for teratogenicity were observed in the rodent, then a developmental test in a second species, preferably the rabbit, would be conducted. The tiered approach provides thorough hazard identification, based on the use of a second species for compounds negative for teratogenicity in the rodent, and maintains maximum public protection based on the extremely low potential for human exposure to these compounds, while making a genuine attempt to limit unnecessary animal testing.