The 5 Second Rule – A Myth?

Who hasn’t used the 5 second rule?  You drop some food on the floor and if it is less than 5 seconds, is it safe to eat?  If it is on the floor longer than 5 seconds, is it really more contaminated?  Does the type of floor matter?  The type of food?  Is the 5 Second Rule another food myth?   Believe it or not, researchers have actually studied the 5 second rule.  What foods did they drop and what did they find?

A number of researchers have studied the 5 Second Rule the most recent study about Myth Debunked, was published in September in the journal of Applied and Environmental Microbiology.  Previously, a high school student studied gummy bears and fudge-striped cookies dropped on a floor contaminated with E. coli.  He found that food was contaminated in less than 5 seconds.   So, what did the 2016 researchers find?

What is the 5 Second Rule – the belief is if you drop any food on the ground/floor and pick it up in less than 5 seconds, the food is less contaminated and thus, “safe” to eat.

Type of surface – the researchers studied dropping food onto different surfaces: stainless steel, ceramic tile, wood and carpet. 

Bacteria – they coated each of these surfaces with bacteria, the bacterium Enterobacter aerogens

Food – they dropped watermelon, plain bread, buttered bread and gummy candy on the different surfaces.

Time elapsed – they let each of these foods be on the ground for 1, 5, 30 or 300 seconds (5 minutes)

Their findings:

The longer the fallen food touched the surface, the greater the contamination.  But even after 1 second, there was some contamination. 

Watermelon, because of its greater water content, was the most contaminated of the foods tested.

Some take-a-ways: 

1. The longer food is on the ground, the more contaminated. 
2. Wetter foods, like watermelon, are more contaminated than foods without much water, like hard candies.
3. Foods falling on carpet are less contaminated than foods falling on ceramic tile or the other surfaces tested.
4. Foods falling on the floor for 5 seconds or less, are not likely to make you sick.

The Berkeley Wellness Letter reviewed this study and noted:  There is a big difference picking up a cracker from a just-cleaned dry kitchen floor, versus the floor near the cat litter box.  So consider where the food has been dropped before munching down the dropped item.

Sources:  Myth Debunked, Berkeley Wellness Letter, Image Source:  Five Second