Simulation of human exposure to benzylpenicillin residues via pork originating from pigs fed with a dairy by-product.

The use of food industry by-products for feeding is restricted by European Union by-product regulation (1774/2002). However, the actual public health risks involved in the use of such products are poorly recognized. This study focuses on bovine milk rejected at the dairy because of a positive result in antimicrobial drug testing and thereafter used as feed for finisher pigs in Finland. In theory, this current practice could expose pork consumers to antimicrobial drug residues. Raw bulk milk samples originating from rejected lots were analysed with a multiresidue method detecting five beta-lactams, including benzylpenicillin. Based on the probabilistic simulation model developed, concentrations of benzylpenicillin in pork invariably remained below 1% of the maximum residue limit. Therefore, the use of this by-product as feed with the current practice was considered to pose only a negligible risk to consumers of pork products.