Most of the antibiotics used in the U.S. are fed to farm animals, not people. And the animals usually aren’t sick—low levels of antibiotics are used continuously because it promotes growth and prevents disease.
Back in 1977, the Food and Drug Administration concluded that this could be a bad thing. Routinely feeding medically important drugs such as penicillin and tetracycline to animals can spawn superbugs—which, in turn, can infect people. For decades the FDA didn’t do much with its findings and never held hearings on the issue. Petitions were submitted to the agency demanding action, and in 2011 the Natural Resources Defense Council and several other advocacy groups filed a lawsuit against the FDA.