The FDA's latest effort to end the use of antibiotics as growth promoters in animals is getting mixed reviews from activists. Rob Carr/AP hide caption

itoggle caption Rob Carr/AP

Pigs take a mud bath at the De Jofrahoeve pig farm in Esch, Netherlands. Dutch farmers treat their animals with almost three times the antibiotics that their Danish neighbors use. Robin Utrecht/AFP/Getty Images hide caption

itoggle caption Robin Utrecht/AFP/Getty Images

Many livestock groups say there's no evidence that antibiotics in livestock feed have caused a human health problem, but researchers beg to differ. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images

Adrian Mesa protests the overuse of antibiotics in meat production outside a Burger King in Coral Gables, Fla. in 2003. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

No chicken, organic or conventionally raised, is completely free of pathogens. Seth Perlman/AP hide caption

itoggle caption Seth Perlman/AP

A truckload of live turkeys arrives at the Cargill plant in Springdale, Ark., on Aug. 4. Most turkeys in the U.S. are given low doses of antibiotics, which breed resistant strains of bacteria, including Salmonella. Danny Johnston/AP hide caption

itoggle caption Danny Johnston/AP