Once again, you've dropped your snack. You bend down, snatch it up, and gently blow off any dust—and, you hope, deadly germs. You're about to put it in your mouth because, after all, you've got the "five-second rule" on your side: Food that's been dropped is safe to consume if it's been on the floor for five seconds or less.
But really, should you eat it? Is the piece of toast or the potato chip or the cookie you just rescued from the ground safe to eat, or contaminated by bacteria? Science says ... maybe.
Researchers at Aston University in Birmingham, England, now suggest that the five-second rule is indeed true.
But a 2007 study of the five-second rule from Clemson University in South Carolina argues that there is no safe window for dropped food. Their data points to a "zero-second rule."