Commonly applied to dropped food, the "five-second rule" is a bit of conventional wisdom that mandates that it is permissible and indeed hygienic to eat food that has been dropped on the floor as long as five seconds have not elapsed from the time that it was dropped.
In 2003, the "five-second rule" was investigated by Jillian Clarke, a high school senior in Chicago. Clarke, who received an Ig Nobel Prize in 2004 for her efforts, swabbed floors at the University of Illinois and found them surprisingly clean of microbes. She therefore concluded that if a floor is clean, it is indeed safe to eat food that has been dropped on it after five seconds. Readers should be warned, however, that Clarke found that if a floor indeed contains microorganisms, food can be contaminated in five seconds or less.
Using a survey, Clarke discovered that 76 percent of women and 56 percent of men in America are familiar with the "five-second rule" and use it to justify picking up and eating treats from the floor. Her research also revealed that women are more likely to eat food that has been on the floor than men, and that cookies and candy are more likely to be picked up and eaten from the floor than cauliflower or broccoli.
Last updated: October 10, 2004.
