If You Drop It, Should You Eat It?: Scientists Weigh In on the 5-Second Rule

URBANA--High-school student Jillian Clarke investigated the scientific validity of the "5-second rule" during her apprenticeship in Hans Blaschek's University of Illinois lab this summer. You know the rule: If food falls to the floor and it's in contact with the floor for fewer than 5 seconds, it's safe to pick it up and eat it.

According to Clarke, a senior at the Chicago High School for Agricultural Sciences, the 5-second rule dates back to the time of Genghis Khan, who first determined how long it was safe for food to remain on a floor when dropped there. Khan had slightly lower standards, however; he specified 12 hours, more or less.

Among Clarke's findings:

• Seventy percent of women and 56 percent of men are familiar with the 5-second rule, and most use it to make decisions about tasty treats that slip through their fingers.
• University floors are remarkably clean from a microbial standpoint.
• Women are more likely than men to eat food that's been on the floor.
• Cookies and candy are much more likely to be picked up and eaten than cauliflower or broccoli.
• And, if you drop your food on a floor that does contain microorganisms, the food can be contaminated in 5 seconds or less. Continue reading...

This stunning piece of research even won an Ig Nobel prize!