The controversial "five-second rule" — the one that allows us to eat dropped food if it's quickly scooped off the floor — is a bunch of baloney, according to Clemson University food scientist Paul Dawson, who stirred up the long-debated issue in a recent issue of National Geographic.
Though previous research has shown we may have up to a minute to rescue certain types of spilled food before it becomes contaminated, Dawson and his students made a strong case for the "zero-second rule." They found that salmonella and other bacteria can live up to four weeks on dry surfaces and be immediately transferred to food.
The zero-tolerance standard, however, conflicts with the findings of two Connecticut College student researchers who sprinkled apple slices and Skittles candies in the college dining hall and snack bar for 5-, 10-, 30- and 60-second intervals. The apple slices picked up bacteria after one minute; nearly five minutes elapsed before the Skittles attracted any.
Still, most researchers agree that the critical thing is not time but location. It's OK to brush off the bagel that fell from the stroller onto the sidewalk and give it to your screaming child, for example, because the pavement is cleaner than the kitchen floor in terms of the types of germs that cause illnesses, said Dr. Harley Rotbart, a professor of microbiology and pediatric infectious diseases at the University of Colorado School of Medicine.