FDA seeks to rescind swine drug approval due to human cancer concerns

The days of using carbadox (Mecadox-Phibro Animal Health), an antibacterial and growth promoter for swine, in the United States may be numbered. According to a press release from the U.S. Food and Drug Administration (FDA), the FDA's Center for Veterinary Medicine (CVM) is taking its first step toward rescinding approval of carbadox.

The concern: It may leave trace amounts of a carcinogenic residue in people who eat pork-especially pork liver-derived from pigs treated with the drug.

“The manufacturer of carbadox has failed to provide sufficient scientific data to demonstrate the safety of this drug given evidence that carbadox may result in carcinogenic residues,” says Michael R. Taylor, FDA deputy commissioner for foods and veterinary medicine, in the FDA release. “As a result, FDA's Center for Veterinary Medicine is taking legal action to remove this product from the marketplace.”

That action is filing a notice of opportunity hearing, which gives the manufacturer of carbadox 30 days to request a hearing on whether carbadox's approval should be withdrawn. If no hearing is requested, the FDA can remove carbadox from the U.S. market. The notice was filed on April 8, 2016.

Carbadox was first approved in the early 1970s with indications for swine dysentery and bacterial swine enteritis. Pork producers have also used the drug for weight gain and feed efficiency.

The issue of toxic residue arose in a World Health Organization (WHO) report in July 2014. A WHO commission determined there was no safe level of residues of carbadox or its metabolites in food that was an acceptable risk to consumers.

Pork liver can be found in liverwurst, hot dogs, lunchmeat and some sausages. But the FDA doesn't think people need to change their diet during this withdrawal of approval process. Since the risk of cancer from consuming pork products that contain carbadox residue is cumulative over a person's lifetime, short-term diet changes are unlikely to affect the risk, according to the release.