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In an unusual step, the Food and Drug Administration is trying to rescind approval of an antibiotic used by pork producers because the medication may leave trace amounts of a carcinogenic residue.

The antibiotic, which is called Mecadox, is used to treat and prevent disease in swine, as well as fatten the animals. An estimated 40 percent of pork producers rely on the medicine, according to a 2012 report by the US Department of Agriculture. Known chemically as carbadox, the antibiotic has been available for roughly 40 years.

The FDA wants to rescind approval after conducting a preliminary risk assessment that found there could be a “potential risk” to humans from eating pork, especially pork liver, derived from pigs that were treated with the drug. Pork liver is used to make liverwurst, hot dogs, lunchmeat, and some types of sausage, the agency noted.


“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 Taylor, FDA deputy commissioner for foods and veterinary medicine, in a statement.

The manufacturer of Mecadox, Phibro Animal Health, was incensed by the move. The company noted the FDA began raising questions several years ago and that since then, it has provided data which, so far, indicate the antibiotic is safe when used according to the product labeling. Phibro added that its studies are due to be completed in 90 days.


“Phibro has complete confidence in the safety of Mecadox. We are disappointed that the FDA would take this action when definitive studies are so close to being completed,” Phibro said in a statement. “Under the FDA’s process, we intend to request a hearing and refute the allegations. Phibro will continue to market the product and to vigorously defend Mecadox based on more than 40 years of science and safe use.”

“This is a fairly rare move,” said Steven Roach of Food Animal Concerns Trust, an advocacy group. “Removing this drug from the food supply is a victory for public health.”

Phibro stock fell 2 percent on the news, which was released this afternoon.