The five-second rule:
How much harm can it do to eat off the floor?
When you drop a piece of food on the floor, is it really OK to eat if you pick up within five seconds? This urban food myth contends that if food spends just a few seconds on the floor, dirt and germs won’t have much of a chance to contaminate it.
Cartoon illustrating the five-second rule
So is five seconds on the floor the critical threshold that separates an edible morsel from a case of food poisoning? The earliest research on the five-second rule reported that when food was placed on floor tiles inoculated with bacteria, the bacteria were transferred from the tile to gummy bears and cookies within five seconds.
Gummy bears were used in early research that to show that bacteria were transferred from the tile to the food within five seconds
But how much bacteria is actually transferred in five seconds?
A more recent study wanted to know if the length of time food is in contact with a contaminated surface affected the rate of transfer to the food. And scientists found that the amount of bacteria transferred to food placed on the floor didn’t depend much on how long the food was in contact with the contaminated surface – whether for a few seconds or for a whole minute.
The overall amount of bacteria on the surface mattered more. The issue was not how long your food languishes on the floor but how infested with bacteria that patch of floor happens to be.
What matters more is how dirty - or bacteria-infested - the floor is
From a food safety standpoint, if you have millions or more cells on a surface, 0.1% is still enough to make you sick. Also, certain types of bacteria, like the E. coli, are extremely virulent, and it takes only a small amount to make you sick. But the chance of these bacteria being on most surfaces is very low.
The E. Coli bacteria
And it’s not just dropping food on the floor that can lead to bacterial contamination. Bacteria are carried by various “media,” which can include raw food, moist surfaces where bacteria has been left, our hands or skin and from coughing or sneezing.
Bacteria and airborne diseases can be spread via respiratory droplets expelled from the mouth and nose, such as a sneeze
So the next time you consider eating dropped food, the odds are in your favor that you can eat that morsel and not get sick. But in the rare chance that there is a microorganism that can make you sick on the exact spot where the food dropped, you can be fairly sure the bug is on the food you are about to put in your mouth.
A case of food poisoning
Research (and common sense) tells us that the best thing to do is to keep your hands, utensils and other surfaces clean.
(All images - credit: Wikimedia Commons under Creative Commons licence)
