The lawsuit in U.S. District Court in Manhattan asked the court to declare that the Food and Drug Administration had violated federal law by failing to withdraw approval of using penicillin and tetracyclines in animal feed when animal health is not at stake.

It said the FDA concluded in 1977 that feeding animals low doses of certain antibiotics could promote antibiotic-resistant bacteria that could infect people, but failed to act to curb their use. As a result, it said, about 80 percent of all antibiotics used in the United States are now used in livestock to promote faster animal growth on less feed, to treat sick animals and to prevent diseases that occur when animals are kept in cramped, unsanitary conditions.

"The misuse and overuse of antibiotics has given rise to a growing and dangerous trend of antibiotic resistance," the lawsuit said. "Increasingly, bacteria are resistant to not one but multiple antibiotics, resulting in infections that are difficult to treat, require longer and more expensive hospital stays, and are more likely to be fatal."

The FDA does not comment on pending litigation, spokeswoman Siobhan DeLancey said.

The lawsuit said research has shown that the antibiotic-resistant bacteria can be transferred from animals to people through direct contact, environmental exposure and the consumption and handling of contaminated meat and poultry products.

"More than a generation has passed since FDA first recognized the potential human health consequences of feeding large quantities of antibiotics to healthy animals," said Peter Lehner, executive director of the Natural Resources Defense Council Inc., an environmental and public health advocacy group and one of the groups in the suit. "Accumulating evidence shows that antibiotics are becoming less effective, while our grocery store meat is increasingly laden with drug-resistant bacteria."

In a release, Lehner added that the FDA risked endangering the primary purpose of antibiotics: "saving human lives by combating disease."

The group said the antibiotics are added to feed or water for pigs, cows, chickens and turkeys at levels too low to treat disease, enabling bacteria to survive in a form stronger and more resistant to medical treatment.

The lawsuit said the worst possible outcome was described by the Institute of Medicine of the National Academy of Sciences, which warned that the "specter of untreatable infections — a regression to the pre-antibiotic era — is looming just around the corner." It also cited a 2009 estimate by Cook County (Illinois) Hospital and the Alliance for the Prudent Use of Antibiotics estimating that antibiotic-resistant infections from all sources cost Americans between $16.6 billion and $26 billion annually.

According to the lawsuit, livestock producers have been adding low doses of antibiotics to the feed of healthy animals since the 1950s.

Other groups involved in the lawsuit are the Center for Science in the Public Interest, Food Animal Concerns Trust, Public Citizen and the Union of Concerned Scientists. They said in a release that the FDA has never fully responded to citizen petitions some of them submitted in 1999 and 2005. They said they filed suit because of growing evidence that the spread of bacteria immune to antibiotics worldwide has clear links to the overuse of antibiotics in the food industry.

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