You know the joke: If you pick up dropped food within five seconds, you can still eat it. Turns our, it's not a joke - and you may have more time than you think. In an experiment at Connecticut College, a group of microbiology students left both wet food (apple slices) and dry (hard candies) on the floor of a cafeteria for intervals ranging from five seconds to five minutes. When they tested their samples for bacterial growth, they found it took 30 seconds for germs to appear on the apples and up to 5 minutes for the candies to become germy. Of course, you have to use good sense too, If the floor is dirty or pets walk on it even a nanosecond could be risky.