by Susan K Wilkerson, RD, LD
The majority of Americans are familiar with the “5 Second Rule.” Drop a piece of food on a dirty surface or the floor, and if you pick it up within 5 seconds, it is not contaminated and is O.K to eat. This is a common superstition and proven to be a myth.
The “5 Second Rule” was featured on an episode of the Discovery Channel series “MythBusters.” They found there was no significant difference in the amount of bacteria collected from a 2-second exposure and a 6-second exposure. The moisture, surface geometry, and location where the food item was dropped did, however, affect the number of bacteria.
Ted Allen put the rule to the test in an episode of “Food Detectives” and found that bacteria will cling to food immediately. High traffic areas will lead to even more bacteria on the food.
So says Dr. Jorge Parada, medical director of the infection prevention and control program at Loyola University Health System. Parada cautioned that as soon as something touches an unclean surface, it picks up dirt and bacteria. The amount of bacteria and what type depends on the object that is dropped and where it lands.
Rinsing off dropped food with water may not clean them entirely, but it could significantly reduce the amount of bacteria on it Parada noted. “Maybe the dropped item only picks up 1,000 bacteria, but typically the amount of bacteria that is needed for most people to actually get infected is 10,000 bacteria – then the odds are that no harm will occur,” he said.
That’s not the case for items that are “cleaned” by licking them off or putting them in the mouth. “That is double-dipping,” Parada explained. “You are exposing yourself to bacteria and you are adding your own bacteria to it. No one is spared anything with this move.”
So the lesson learned here is if food drops on an unclean surface, throw it out. No minimal amount of time is safe from bacterial contamination.