Quinoxaline-2-carboxylic acid in pigs: criteria to distinguish between the illegal use of carbadox and environmental contamination

Abstract

Carbadox cannot be used in food-producing animals within the European Union following the adoption of Commission Regulation EC 2788/98/EC. Monitoring of the longest remaining residue—quinoxaline-2-carboxylic acid (QCA)—is the most effective way of enforcing the prohibition on its use. The study was under taken to determine if QCA could be passed from pig to pig following the exposure of unmedicated animals to housing that had previously contained medicated animals. Drug-withdrawal studies were also carried out on medicated animals. Distinction between treated animals and those exposed to QCA might be required by competent national authorities to determine whether a positive result for QCA in tissue is truly ‘violative’. Comparison of the ratio concentrations of QCA in tissues and body fluids was made to determine if they could be used as criteria for discrimination between illegally treated animals and environmental contamination.

Keywords:

• carbadox
• residues
• pigs
• quinoxaline-2-carboxylic acid (QCA)

Acknowledgements

The authors acknowledge the support of DARD for funding a studentship (M. J. H.), which enabled the work to be carried out.