Food recalls may well be increasing, partly due to better technology and greater awareness of the possibility for microbial contamination. “We are certainly much better at finding contamination, and there is stepped up surveillance,” says Glass, a microbiologist, but counting recalls does not prove that food is more dangerous.

The deadly bacterium E coli O157, for example, started appearing in hamburger about two decades ago, changes in manufacturing processes have caused it to grow less common in U.S. Department of Agriculture hamburger inspections. “But they are finding the proverbial needle in haystack,” says Glass. “While the rate of contamination has decreased, the number of ground beef recalls has increased from eight in 2006 to 20 in 2007 because more samples are surveyed.”

Yet during the same period, fewer human O157 infections have been confirmed in health laboratories, she adds. “We recall more, but are finding an overall reduced incidence of E coli in ground beef, and are also reducing the rate of lab-confirmed infections. So what interpretation can you make? That the food-safety system is working, even though the number of recalls is rising.”