You know the five-second food-on-floor rule? It's a sham, says science

 When it comes to life lessons, every child is taught to look both ways before they cross the street.

 

They're also told that when you drop food, you have a five-second grace period where you can pick it up, wipe it off and pop it into your mouth without worrying about anything happening to you. 

 

In fact, this five-second rule is essentially what got us through childhood, uni and pretty much every festival we've ever attended. 

 

Unfortunately, like lots of other things we believed in childhood, it's all a lie. 

 

Researchers at Rutgers University have published a new study in the American Society for Microbiology's journal, Applied and Environmental Microbiology, which found that food dropped on the floor can pick up bacteria in five seconds or less.

 

In fact, food can be contaminated in less than one second. Eww.

 

The scientists decided to look into the rule precisely because it's so prevalent in pop culture, and discovered that moisture, the type of surface you drop food on and contact time all play a role in contaminating your food.

 

Testing on four surfaces – stainless steel, ceramic tile, wood and carpet, which were coated with Enterobacter aerogenes, which mimics salmonella's attachment skills – professor Donald Schaffner and graduate student Robyn Miranda tried out four different types of food (watermelon, bread, bread and butter and gummy sweets). They also used four different contact times: less than one second, five seconds, 30 seconds and 300 seconds.

 

They dropped the different food on to the various surfaces to create 128 scenarios that they repeated 20 times each, for a total of 2,560 measurements.

 

The research showed that contact time does influence bacterial transfer (more bacteria is transferred when there are longer contact times), but other factors, like the type of food and the surface it's dropped on, are equally or even more important to consider.

 

Watermelon was the most highly contaminated – the transfer of bacteria from surfaces to food is affected most by moisture, the scientists found. Food dropped on the carpet had less bacteria than food dropped on tile or stainless steel.

 

"The five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food," Schaffner told Rutgers Today. "Bacteria can contaminate instantaneously."

 

There is some good news. Gummy sweets had the least contamination of the four foods tested.

 

So, if you spill your pack of Jelly Babies on the cinema carpet, we won't judge. We promise.