In 1999, the European Union backed a ban on penicillin and other human antibiotics for growth in farm animals. Within four years, the use of antibiotics on animals fell 36 percent in Denmark, 45 percent in Norway and 69 percent in Sweden.
Levy, the Tufts University professor, and his colleagues had hoped that the EU's ban would bolster the case for restricting the use of antibiotics in the United States. But instead, the data has been used to argue both sides of the issue.
U.S. farmers have seized on reports that cases of diarrhea among young pigs increased in the first year after the EU ban, suggesting that animal health had declined. But public health advocates say that the outbreaks among pigs decreased once farmers improved the sanitary conditions by cleaning feedlots more frequently and giving animals more space.
U.S. groups like the National Chicken Council warn that restricting use of antibiotics will result in sicker animals, increasing costs for farmers — and the price of meat and poultry for consumers. Some industry groups have projected costs for farmers would rise by $1 billion over 10 years, though those estimates have not been backed by outside groups.
Liz Wagstrom, chief veterinarian of the National Pork Producers Council, said the modern farming system is designed to keep animals healthy and produce large quantities of meat.
"The bottom line is that if these products go away, it may result in sicker pigs, more expensive food, and we don't think it will improve public health," Wagstrom said.
Meat prices in Europe have not risen dramatically since the EU's ban. Danish authorities estimate the total costs for pig farmers increased by just 1 percent, or about $1.35 for every pig slaughtered — far below food industry estimates.
U.S. health experts suggest the increase here would be modest, too. The Institute of Medicine, a non-partisan nonpartisan group of medical experts who advise the federal government on public health issues, estimates the average U.S. consumer would spend between $5 and $10 more per year on meat if antibiotics were restricted.
Farmers continue to argue that antibiotics are necessary to have a steady supply of low-cost, disease-free meat for Americans, who eat about three-quarters of a pound per day — roughly twice the global average. They acknowledge that antibiotic-free animals can be raised by small, organic farms but say large-scale meat production requires antibiotics to keep animals healthy.
"We're pretty darn committed to our cattle, and our goal is to not have them get sick," said Mike Apley, a cattle farmer and professor of veterinary medicine at Kansas State University.