EFSA's assistance for the 2015 Codex Committee on Residues of Veterinary Drugs in Food (CCRVDF) in relation to rBST

Abstract

This report evaluates the safety of recombinant bovine somatotropin (rBST), used as a milk production enhancer in dairy cattle, in relation to human health. The existing evidence of a direct link between the use of rBST in dairy cattle and antimicrobial resistance (AMR) in humans is assessed. The main intermediate steps that may indirectly link the use of rBST in dairy cattle and AMR in humans are also assessed, namely: possible link between use of rBST and the occurrence of mastitis in dairy cattle; possible link between occurrence of mastitis and the use of antimicrobials in dairy cattle; possible link between treatment with antimicrobials and AMR in dairy cattle (and in dairy cattle farms); and, possible link between AMR in dairy cattle (and in dairy cattle farms) and AMR in humans. Assuming that treatment with rBST can lead to an increased incidence of mastitis in dairy cattle, that cases of mastitis are usually treated with antimicrobials, that the use of antimicrobials can lead to the development of AMR in dairy cattle (and in dairy cattle farms), and that AMR in humans may derive from both the exposure to AMR bacteria/genes of cattle origin and residues of antimicrobials, it is concluded that an increase of AMR in humans following the use of rBST in dairy cattle is plausible. Current knowledge does not allow quantifying these four steps. Recommendations for additional studies to investigate these four steps and quantify them are formulated.