Antibiotics in livestock production is currently under heightened scrutiny by Congress. The debate took its latest turn on Tuesday, when U.S. Rep. Louise Slaughter, D-NY, introduced legislation that would require drug manufacturers to go through a new approval process to ensure that antibiotics used in farm animals don't pose a danger to human health.

Slaughter said mounting evidence showed that routine antibiotic use in factory farms was leading to drug resistance in humans. Many medical professionals fear the development of a so-called lethal "superbug" resistant to treatment.

The pharmaceutical and agricultural industries have pushed against similar efforts in the past. Pork producers say that antibiotics are a necessary part of good farm management and that the health risk is minimal.

"The ones currently being used in animals are old antibiotics. They've been used for 50 years," said Scott Hurd, an epidemiologist for Iowa State University. "If the 'superbug' was going to develop, it would have developed already."

Hurd is the former undersecretary for food safety at the Food and Drug Administration, and his research has been supported by the U.S. Department of Agriculture and the pharmaceutical industry.

Illinois and Missouri are among the country's top pork-producing states, and producers here and elsewhere in the Midwestern "hog belt" say antibiotic use is exaggerated. But the loss of antibiotics as a tool could cost the industry millions of dollars, they caution.

"There are some conditions where a low-dose therapy may be the right decision," said Craig Rowles, a veterinarian and hog producer from Caroll, Iowa, the nation's top pork producing state. "People think they're used indiscriminately, and that's not true."

The legislation Slaughter introduced is similar to others that have failed in recent years. The bill aims to curtail the use of antibiotics for everyday use. Critics say the drugs fatten the animals more quickly and compensate for crowded conditions in large-scale operations. Slaughter said 84 percent of feedlots administered antibiotics in feed or water.

"It makes absolutely no sense to hand this to animals that aren't sick," she said. "We're misusing one of the best scientific tools we have."

It's not clear how much antibiotic use in food animals has risen in the past three decades, since confined animal feeding operations, or CAFOs, became the norm in American livestock production. One study, by the Animal Health Institute, a pharmaceutical industry group, showed that volume sales have gone up, but the report looked at only a three-year period.

"It's one of the great tragedies of this issue that there are simply no good data, gathered by a central agency," said Margaret Mellon, of the Union of Concerned Scientists, an environmental group in Washington.

Mellon's group conducted a study showing that American food animals consume 70 percent of the antibiotics in this country — 25 million pounds a year — for non-therapeutic uses.

Farmers say those uses are justified, and claim there's a lack of evidence showing a link between animal antibiotic use and resistance in humans. "We don't take antibiotics in the morning so we don't get sick," Hurd said. "But people don't understand that on the farm, we want to prevent disease."

But Mellon, and critics of animal antibiotic use, including the American Medical Association, point to growing evidence of a link. The European Union has banned the use of some antibiotics for routine use.

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