Sufonamides are widely used for therapeutic and prophylactic purposes in animal diseases. When they are retained in food this may result in allergic or toxic reactions in sensitive consumers. Moreover, there is a general concern that the widespread use of antibiotics could contribute to antibiotic resistance in pathogenic organisms. Normally, tissue residues in animals are controlled by withdrawing the drug from feed before slaughter. The concentrations of the sulfonamides are then presumed to deplete to less than the maximum residue level (MRL). However, due to contaminated food or failure to observe the withdrawal period, a number of animals are reaching slaughterhouses with a substantially excessive amount of drugs still present in their tissues.
Community MRLs of 100 ng/g have been established for the sum of all sulfonamide residues in tissues of food producing animals (muscle, fat, liver and kidney) and in milk.