Environmental and consumer groups have condemned the US Food and Drug Administration's move to renege on its long-held policy to regulate the use of human antibiotics in animal feed.

Last week, the agency quietly announced it was withdrawing its plan to limit the use of antibiotics fed to healthy livestock intended for human consumption.

Critics say the U-turn, which comes amid the FDA's own stated concerns over food safety, is at odds with its obligations to protect the public.

The groups also criticised the timing of the announcement, which was made during the holiday season and disclosed only in the federal register.

The use of low doses of antibiotics in agricultural animal feed contributes to drug-resistant superbugs, according to food and health experts.

One leading food policy writer described the policy reversal as "pathetic" and "dismaying."

"It's dismaying, and obviously something they felt sheepish about, otherwise it wouldn't have been released this week," Michael Pollan, author of the Onmivore's Dilemma and Food Rules: An Eater's Manual, told the Guardian.

"When Margaret Hamburg became the head of the FDA, she indicated this was a high priority for them and that she realised how much of a problem the profligate use of antibiotics was. She said she was going to treat this issue as if her hair was on fire. This isn't the way someone acts when their hair is on fire."

Pollan said there was "no question" that meat could be produced without human antibiotics, as the EU has already banned them.

The FDA first acknowledged in 1977 that the overuse of antibiotics in healthy livestock for growth promotion and disease prevention was unsafe and could promote antibiotic resistant bacteria that could infect people. An advisory committee at the time recommended that the FDA immediately withdraw approval for two drugs, penicillin and tetracycline, for subtherapeutic uses of the drugs in livestock.

Last week, in a statement in the Federal Register, the FDA says it plans instead to allow the industry to self-regulate and "focus its efforts for now on the potential for voluntary reform and the promotion of the judicious use of antimicrobials in the interest of public health".

The problem, said Pollan, boils down to a lack of political will in the face of powerful industry interests. "There's a lot of corporate money in politics these days," he said. "Here you're going up against not just one powerful industry, but two. This administration has had enough trouble going after individual powerful industries. That they would prevail against two of them joined together was too much to hope for."

Livestock consume about 80% of the antibiotics sold in the US.

The FDA's decision comes after a number of high profile meat recalls. In August, 36m lbs of turkey meat were found to have been contaminated with drug-resistant salmonella that caused one death and 76 people to become ill.

When approached by the Guardian, a spokesman for the FDA could not provide anyone for comment.

A statement, taken from the Federal Register, said: "FDA continues to view antimicrobial resistance as a significant public health issue. Today's action should not be interpreted as a sign that FDA no longer has safety concerns about the use of medically important antibiotics in food-producing animals, or that FDA will not consider re-proposing withdrawal proceedings in the future if necessary."

But Avinash Kar, an attorney with the Natural Resources Defense Council (NRDC), described the move as a "step backwards" for the FDA.

Kar believes the move is an attempt to get around a lawsuit filed by the NRDC to force the FDA to withdraw approval for the practice of mixing human antibiotics into animal feed. The lawsuit, filed in May, asked the court to declare that the FDA had violated federal law by failing to withdraw approval of using penicillin and tetracycline in animal feed when animal health is not at stake.

"This action by the FDA is a response to our lawsuit" said Kar. "The findings in 1977 were included in the notice for opportunity for a hearing, and they think they can get around the lawsuit by withdrawing the notices for opportinuties for a hearing. But we will not allow the FDA to ignore public health."

In response to the FDA's reliance on voluntary regulations, Kar said: "We don't believe that the industry will voluntarily regulate itself, because for the last 33 years the approach has been voluntary and the use of antibiotics in livestock has not gone down but – based on estimates – has gone up."

"The science has only gotten stronger."

Stephen Roach, of the Food Animals Concern Trust, a group also involved in the lawsuit against the FDA, said he believed the FDA was putting public health at risk.

"It is totally at odds with their mission to protect the public. This month we had a salmonella outbreak in the north-east that was resistant to penicillin and the drug that replaced penicillin, cephalosporin. We are going to continue to have multi-drug resistant salmonella outbreaks and E.coli drug-resistant outbreaks."

Roach said the use of low doses of antibiotics in animals over a long period of time created the ideal conditions for bacteria to develop drug resistance.

A growing number of scientific and medical institutions have urged action on antibiotic resistance. The World Health Organisation devoted a WHO day to microbial resistance.

In September, several institutions, including the American Medical Association, the Infectious Diseases Society of America and the Pediatric Infectious Diseases Society, wrote a letter to Congress, calling for them to to reiterate the link between antibiotic resistance and the overuse of antibiotics in food animals. Some of the same health groups took ads out in Politico and The Hill.

"Hundreds of scientific studies conducted over four decades have shown that feeding low doses of antibiotics to healthy food animals leads to drug-resistant infections in people," they wrote in the ad. "In fact, America's leading medical, scientific and public health organizations have been warning of the danger for years."

Politicians also expressed dismay at the FDA's move.

In a statement on her website, Democratic congresswoman Louise Slaughter, the author of the Preservation of Antibiotics for Medical Treatment Act (Pamta), a legislative framework aimed at tackling antibiotic resistance, said: "Every year, 100,000 Americans die from bacterial infections acquired in the hospital and this is just the tip of the iceberg. Seventy percent of these infections are resistant to drugs commonly used to treat them. I wonder how many lives could have been saved if these proposals were adopted in 1977 as they should have been.

"We need to get our head out of the sand and start taking public health advice from scientists rather than industry lobbyists."