Whenever my son drops food on the floor, he wants to eat it. I discourage him from doing so, but he invokes the "5-second rule" and says that food is safe to eat if you pick it up 5 seconds or less after it has hit the floor. Is that true?
Research has proved that the 5-second rule is wrong. Bacteria can attach to food even if it's picked up very fast. So it's not a good idea to eat food that has hit the floor.
While floors that look dirty are obvious hazards, even floors that appear clean can harbor bacteria. Some germs can survive on floors for a long time, and without a powerful microscope it's impossible to determine how many are present.
Bacteria can attach to food as soon as it hits the floor. That means that even food left on the floor just for an instant can become contaminated if conditions are right. And foods with wet surfaces, like an apple slice, can pick up bacteria more easily. The longer food is on the floor, the more bacteria it will accumulate.
Some bacteria are not harmful. But others can make a person sick. You can't see the bacteria and, even if you could, it doesn't take many to make someone sick.
So what are you to do with that delicious piece of whatever that just slipped from your grasp? The safest choice is to throw it out.