Michael Greger of the Humane Society of the United States misstated the scientific record on salmonella and "cage-free" egg farms [letters, Sept. 17]. One of the studies that Mr. Greger cited concluded that "the system with the lowest chance of infection was the cage system." Others on his list noted confounding factors that distort results, such as flock size and vaccination rates. Most of the studies examined European farms, not U.S. ones.

Poor farm management was the biggest issue fueling the recent salmonella outbreak — not "cage" vs. "cage-free." A 2010 review of international scientific literature in the journal Poultry Science found "no general consensus demonstrating the superiority of one housing situation over another regarding food safety and egg quality." There may be a strong animal rights rationale for embracing "cage-free" egg farming, but there are no valid food safety reasons.