Bill Tomson of the Wall Street Journal asked that question today.

Screen Shot 2011-08-12 at 9.54.17 PM.pngLivestock consumed some 28.6 million pounds of antibiotics in 2009, most of it in feed, according to the Food and Drug Administration. While that may prevent disease in the short term, some food-safety specialists say that over time, the heavy use promotes the evolution of bacteria that can fight off the drugs and threaten humans.

A particularly dangerous antibiotic-resistant strain of bacteria called salmonella Heidelberg has sickened more than 100 Americans and killed one person since this spring, when it contaminated ground turkey produced by Cargill Inc., according to the government. Cargill recalled 36 million pounds of ground turkey on Aug. 3.

Broad use of antibiotics in livestock goes back decades, as does concern about resistant superbugs. As early as 1970, the FDA began reviewing the issue, but it has held back from tight restrictions because data on human health risks were uncertain.

How certain is it now?