The alarming rate of growing drug resistance in humans has prompted US regulators on Wednesday to give a series of voluntary measures to limit the use of antibiotics in healthy livestock and farm animals.
However, the move drew skepticism from consumer advocates who said it fell far short of the measures needed to make sure that unnecessary antibiotics are kept out of the US food supply.
"Under this new voluntary initiative, certain antibiotics would not be used for so-called 'production' purposes, such as to enhance growth or improve feed efficiency in an animal," said the Food and Drug Administration in a statement.
"These antibiotics would still be available to prevent, control or treat illnesses in food-producing animals under the supervision of a veterinarian."
Farmers who want to use animal feed that contains antibiotics would need a veterinarian's prescription, according to final guidance for industry published Wednesday.
In addition, two draft guidances, open for a public comment period, will "assist drug companies in voluntarily removing production uses of antibiotics from their FDA-approved product labels," and outline how vets can permit use of certain animal drugs in feed.
Critics said the measures do not call for an end to the use of preventive use of antibiotics to healthy animals and that tougher action is needed to stop a dangerous practice that can create superbugs and infections that are resistant to current treatments.
"Public health authorities in the US and around the world agree that the overuse of vast quantities of antibiotics on livestock to hasten weight gain and compensate for crowded, filthy conditions is contributing to the crisis of antibiotic resistance in human medicine," said Avinash Kar, an attorney with the Natural Resources Defense Council.
"This is an ineffective response to the real and sobering threat of rising antibiotic resistance, which threatens human health."
Kar added that 80 percent of antibiotics sold in the United States are used for livestock, and so the pharmaceutical industry has an interest in maintaining the status quo.
"Put another way, industry is not required to do anything," he said.
"Even if a couple of actors make the right moves out of the goodness of their hearts, that won't ensure change in the whole industry, which is the level at which change is required."
The Center for Science in the Public Interest called the FDA policy "tragically flawed" and warned that "decades of misuse have led to some common pathogens, like salmonella, becoming more virulent and less treatable."
The FDA's deputy commissioner for foods, Michael Taylor, told reporters he was aware that some would question the agency's decision to pursue voluntary measures instead of an outright ban.
"The answer is, with the willingness of drug companies and others in the animal production industry to collaborate in implementing our strategy, we can make changes more quickly than if we had to rely solely on a cumbersome regulatory process," Taylor said.
He described the formal ban proceedings that the FDA could pursue as an "expensive, lawyer-driven process."
"Given that there are in the vicinity of a couple of hundred products involved here, the prospect of going case by case through that process -- I mean, that's decades of effort and millions and millions of dollars in resources," Taylor said.
In January, the FDA announced restrictions on the use of certain antibiotics called cephalosporins in cows, pigs and poultry due to concerns that infections in humans may be growing resistant to treatment.
The FDA's final guidance issued Wednesday was based on a draft of the same rules submitted in 2010, but it was unclear whether the draft had resulted in any significant change in the level of antibiotics fed to farm animals.
New York Congresswoman Louise Slaughter, a microbiologist who has advocated against the use of antibiotics in farm animals, applauded the move as a step in the right direction but said the FDA should press further.
"'Nonbinding recommendations' are not a strong enough antidote to the problem, particularly when we know that banned antibiotics are still being detected," she said in a statement.
"Additionally, the FDA's pace here has been nothing short of glacial. They need to move more quickly when the health of the American people is at stake."