Antibiotic resistance is a problem both for people and for livestock. But how can we be sure that the two are connected and that resistance is exacerbated by on-farm antibiotic use? In 1975 the Animal Health Institute asked this very question and recruited Tufts University biologist Stuart Levy to find out. Levy and his colleagues fed low doses of the antibiotic tetracycline to a group of 150 chickens. Within a week, almost all the E. coli bacteria in their intestines were tetracycline-resistant. Three months in ... the chickens were also resistant to four other types of antibiotics. After four months, the ... chickens on the farm that had not been fed tetracycline also harbored resistance to the drug. In 1977, soon after Levy's study was published, the FDA announced that it was considering banning several antibiotics from animal feed over safety concerns. In the 39 years since, the industry has fought hard against these plans by arguing there was no definitive proof of harm. These arguments ultimately caused the FDA to [pursue] voluntary guidances instead. Several members of the U.S. Congress, including New York State Representative and microbiologist Louise Slaughter, have introduced bills to more tightly regulate antibiotic use on farms. Slaughter has pushed for her Preservation of Antibiotics for Medical Treatment Act for more than a decade. It has been supported by 454 organizations, including the American Medical Association. But ... the bill never reaches a vote.