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On Nov. 7, the U.S. Food and Drug Administration (FDA) announced it is considering withdrawing approval for the antibiotic carbadox, which is added to pig feed to prevent infections and fatten up the animals, due to cancer concerns.
The drug has been banned in the European Union (EU) since 1999, and in Canada since 2006. China, Brazil, Australia and the U.K. have also banned it due to concerns over its cancer risks.
In 2014, the United Nations (U.N.) Codex Committee on Residues of Veterinary Drugs in Foods determined that there is no safe level of residues of carbadox or its metabolites in food that represents an acceptable risk to consumers.
Carbadox has been shown to cause liver cancer and birth defects in lab animals, and have long-lasting impacts on the gut microbiome of swine, even after the drug is withdrawn.
A 2017 study found carbadox-induced transducing bacteriophages with resistance genes to tetracycline, aminoglycoside and beta-lactam antibiotics — three classes of drugs that are commonly used in human medicine. The findings effectively dismiss the drugmaker’s and the National Pork Producers Council’s argument that since carbadox is not used in human medicine, it won’t contribute to drug resistance in humans.