Use of rBST in dairy cattle and AMR in humans

First published in EFSA Supporting Publications
23 June 2015
18 June 2015
Technical Report

The use of recombinant bovine somatotropin (rBST) as a milk production enhancer in dairy cattle is authorised in some countries but is banned in others, including the Members States of the European Union. At the request of the Codex Alimentarius Commission, the Joint Expert Committee on Food Additives (JECFA) evaluated in three different occasions several aspects related to the safety of rBST and concluded that there was no evidence to suggest that the use of rBST would result in a higher risk to human health due to the possible increased use of antimicrobials to treat mastitis. JECFA assessments consider human health concerns related to the exposure to residues of antimicrobials in milk. They do not consider other aspects related to antimicrobial resistance (AMR), such as the possible development of AMR in dairy cattle and dairy cattle farms following to the treatment with antimicrobials and the possible development of AMR in humans due to the exposure to pathogenic and non-pathogenic resistant bacteria originating from the cattle reservoir. Assuming that treatment with rBST can lead to 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 to 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.

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