The Five-Second Rule

Have you heard about the five-second rule? I just read about these interesting findings in Wikipedia this morning and like to share them with you:

"Basically, the five-second rule applies to foods—particularly solid foods—that have fallen to the ground. Normally, customary rules of hygiene dictate that food that has fallen to the ground should be discarded, in order to prevent ingestion of disease-causing agents acquired from the dirty surface. The rule states that if the food is picked up within five seconds, it can still be eaten.

In reality, it is usually safe to eat food from a relatively clean floor. However, the notion that germs from a dirty floor will not reach food for at least five seconds is false. For this purpose, cleanliness is a matter of bacterial or parasitic contamination rather than visible dirt, although the two often go together. For example, sick people attend hospitals, with the result that a hospital floor which has not been decontaminated properly can appear to be relatively clean, while actually being more contaminated than the dirty street outside.

A study on the five-second rule was performed by Jillian Clarke, a high school senior, during a seven-week internship at the University of Illinois at Urbana-Champaign in 2003. Clarke and a doctoral candidate named Meredith Agle took swab samples from various floors around campus. They then looked at the samples under a microscope and discovered that they did not contain significant amounts of bacteria. The conclusion was that in most cases, dry floors would be safe to eat from.

However, Clarke also wanted to test the five-second hypothesis in cases where the floor was known to be contaminated. She therefore spread E. coli on both rough and smooth floor tiles in a laboratory, placed pieces of gummy bears and cookies on the tiles for various amounts of time, and then examined the foods under the microscope. All the foods had a significant amount of bacteria in less than five seconds.

In the course of her research, Clarke also conducted a survey to sample opinion on the five-second rule. She found that seventy percent of women and fifty-six percent of men were familiar with the five-second rule, and most utilized the rule in their decisions to eat food that had fallen on the floor. She also found that women were more likely than men to use the rule, and that cookies and candy were more likely to be picked up than broccoli or cauliflower.

Clarke's work won an Ig Nobel Prize for Public Health in 2004.

The five-second rule was also featured in an episode of the Discovery Channel series MythBusters. The results they got from their tests confirmed Clarke’s findings: time was not a factor when food is exposed to bacteria; even two seconds' exposure is more than enough time to contaminate it."