/ Source: TODAY
By Barbara Mantel

Everyone's done it: Dropped some food on the floor, quickly picked it up and eaten it -- or fed it to a child. The old 5-second rule claims bacteria will have no time to climb aboard if the food hasn't been in contact with the floor for more than five seconds. But is it right?

Wrong, according to researchers at Rutgers University, who studied four different foods, dropped onto four different surfaces, for four different amounts of time. As part of the test, the researchers liberally applied Enterobacter aerogenes, a nonpathogenic “cousin” of salmonella, to each surface.

“At the shortest amount of time we studied, which was a fraction of a second, no matter what food and what surface, we always found some bacteria transfer in at least one of our experimental trials,” says Donald Schaffner, a food science professor at Rutgers University and the lead author of the paper, published in the journal Applied and Environmental Microbiology.

The researchers conducted multiple trials of each combination of food, surface and contact time.

Seconds count

While they showed the 5-second rule to be untrue, time does matter, said Schaffner. For many foods and many surfaces, the longer the food sat on the floor, the more bacteria it collected. That’s probably gravity at work, he said, pressing the food down and expanding the surface area in contact with the floor’s germs.

You may think it's no big deal, but about 12 percent of food-borne illness reported to the Centers for Disease Control and Prevention is the result of cross-contamination of food from surfaces.


Related: Is the five-second rule real?