The U.S. Food and Drug Administration's Center for Veterinary Medicine (CVM) have taken the first step toward rescinding its approval of the use of carbadox to treat swine because the drug may leave trace amounts of a carcinogenic residue.

CVM's action comes after the center recently reexamined the safety profile of the drug and conducted a preliminary risk characterization that indicated there could be potential risk to human health from ingesting pork, especially pork liver, derived from carbadox-treated pigs.

"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," said Michael R. Taylor, FDA deputy commissioner for foods and veterinary medicine. "As a result, FDA's Center for Veterinary Medicine is taking legal action to remove this product from the marketplace."

The FDA is not recommending that people make changes in their food choices while the agency is working to remove carbadox from the market. Potential cancer risks are based on an assumed lifetime of consuming pork liver or other pork products containing carbadox residues, and short-term changes in diet are unlikely to affect a person's lifetime risk. However, removal of the product from the market will reduce the lifetime risk to consumers, which is why CVM is taking this action. Pork liver is used to make liverwurst, hot dogs, lunchmeat and some types of sausage. In general, eating a varied diet may reduce the potential negative effects of eating too much of any one food.

FDA-approved alternative antibiotics are available to pork producers to treat swine.

CVM is committed to working with pork producers to minimize impacts on the swine industry.

Carbadox was first approved in the early 1970s for use in swine to control swine dysentery and bacterial swine enteritis. It has also been used for weight gain and feed efficiency.

In July 2014, the Codex Alimentarius Commission determined there is no safe level of residues of carbadox or its metabolites in food that represents an acceptable risk to consumers. This was based on the Food and Agriculture Organization of the United Nations/World Health Organization Codex Committee on Residues of Veterinary Drugs in Foods' conclusions on the available scientific information.

To remove its approval, CVM must first file a Notice of Opportunity for Hearing, which it issued today. The notice provides the manufacturer of carbadox with an opportunity to request a hearing on whether the approval should be withdrawn.

The company has 30 days to request a hearing. If the company does not request a hearing, the agency can proceed with removing the animal drug from the market.

The manufacturer of all of the drug applications for carbadox is Phibro Animal Health, based out of Teaneck, New Jersey.