The U.S. Food and Drug Administration is a step closer to revoking the approval of a swine drug over concerns that it could leave trace amounts of a carcinogenic residue. According to its preliminary risk assessment, the risks to human health are present when consuming pork, particularly pork liver.
Carbadox, manufactured by New Jersey-based Phibro Animal Health, is an antibiotic drug designed to combat pig infections such as bacterial enteritis and swine dysentery - and mostly to fatten up pigs for slaughter.
While consumer groups are alarmed over how heavy use of the drug is contributing to antibiotic resistance and the creation of superbugs, the FDA is worried about an altogether different risk.
"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 Taylor, deputy commissioner of FDA for foods and veterinary medicine, in a statement.
The FDA's move follows a preliminary risk assessment done from 2012 to 2014, which discovered that the lifetime cancer risk from intake of pork liver with carbadox residue is higher than what the federal agency allows under its framework for regulating carcinogenic animal drugs.
A number of studies have demonstrated that the drug can lead to cancer in rats, with the potential for sticking around in pork products ingested by humans.
"In rats, carbadox was reported to cause a dose-dependent increase in the incidence of benign and malignant hepatic tumors and of mammary tumors at doses [higher than] 1 mg/kg bw per day," states a report from the University of Leipzig in Germany, confirming that both carbadox and one of its components, desoxycarbadox, "should be regarded as carcinogens."
The risk is said to be particularly present in pork liver, used for producing hotdogs, liverwurst, lunchmeat, and other kinds of sausage.
The FDA, though, is not recommending dietary changes just yet, citing that pork serves as a good protein source.
"[H]owever, protein can also be found in other meat, poultry, seafood, beans and peas, eggs, processed soy products, nuts and seeds," the agency adds.
Carbadox is already limited in use in Canada, the European Union and Australia. In the U.S., pork producers are not required to report to the FDA the specific drugs they use; drug sponsors are only required by law to reveal sales data, which is not directly indicative of actual drug use.
There is growing interest in carbadox because it does not require veterinary prescription, according to John Goihl of Minnesota-based Agri-Nutrition Services, which offers livestock consulting and feed formulations. Three antibiotics of Phibro - namely Mecadox Premix 10, Banminth/Mecadox, and Mecadox/Terramycin - contain carbadox.
Phibro, which is yet to provide additional safety information requested by the FDA, insisted in its statement that Mecadox is safe, and has been legally sold in the country for over 40 years.
Photo: Liz West | Flickr
