A study released earlier this year by Aston University, one of England's top universities, investigated how often people would eat food that had fallen on the floor, either in a kitchen or dining room.

The researchers found that:
• 87 percent of people surveyed said they would or have eaten food dropped on the floor — 55 percent of those were women

• 81 percent of the women who would eat food from the floor would follow the "five-second rule."

The five second rule is an old belief that says if food is picked up quickly enough from the floor-within five seconds-it is safe to eat. 

According to the Aston researchers, this may actually be true. The study was led by Anthony Hilton, Professor of Microbiology, and biology students at the school. They monitored the transfer of common bacteria, such as E. coli and Staphylococcus aureus from food that had fallen on a variety of indoor floor types, including carpet as well as laminate and tiled surfaces.
The food was allowed to remain on the floor from three to 30 seconds. The results showed:
• Time is a significant factor in the transfer of bacteria from a floor surface to a piece of food
• Bacteria was least likely to transfer from carpeted surfaces and most likely to transfer from laminate or tiled surfaces
• If the transfer of bacteria occurred, the contact required five seconds or more.

"Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor and the type of floor," says Hilton.
And few commercial kitchens have carpeted floors, says Matt Morrison, communications manager for Kaivac, which manufactures equipment often used for commercial kitchen floor cleaning.
"Commercial kitchen floors become very soiled very fast, which leads to bacteria growth," says Morrison. "We advise our [restaurant] customers to forget the five second rule and make sure floors are kept clean throughout the day and thoroughly cleaned at the end of each shift."