On Capitol Hill today, the Obama administration spoke out in support of new legislation that would prohibit the use of antibiotics on healthy livestock. Principal deputy commissioner of food and drugs Dr. Joshua Sharfstein warned that the overuse of antibiotics on America’s chicken, pigs and cattle could eventually lead to resistant bacteria strains in humans that will be difficult to treat.

Dr. Sharfstein testified at a hearing for a new bill sponsored by Rep. Louise Slaughter (D-N.Y.) that would prohibit food producers from using seven classes of antibiotics that could pose a particular risk to humans. The legislation would also regulate a handful of other animal antibiotics, restricting their use to strictly therapeutic and preventative purposes.

Although the bill has gained the support of the American Medical Association and the Union of Concerned Scientists, a number of major food lobbyists have come out against the measure, making its passage unlikely. Organizations like the National Pork Producers Council argue that there is no scientific evidence that antibiotic use leads to an increase in human illness or bacterial resistance. Pork lobbyist Dave Warner told The New York Times, “There are no good studies that show that some of these antibiotic-resistant diseases–and it seems like we’re seeing more of them–have any link to antibiotic use in food-animal production.”

According to the American Veterinary Medical Association, however, it doesn’t look like antibiotics have been beneficial either. Speaking at an AVMA conference in May, Dr. Frederick Angulo, deputy branch chief of the CDC’s Enteric Diseases Epidemiology Branch, said there is no definitive proof that antibiotic use contributes to faster growth. He cited Denmark’s ban on antibiotics for growth promotion, which had little effect on production.