The 5-second rule? More like 5-second fantasy

fallen toasted on the floorIf you drop food on the floor is it really safe to pick it up and eat it within five seconds? This popular urban legend was the question of a recent study where scientists experimented with different types of foods and different types of floor surfaces to find out the accuracy of “the five second rule.”

First, however, where exactly did this urban legend come from? While it’s difficult to pin down, according to a recent article, Julia Child may have had something to do with it. During one of her cooking shows, she reportedly dropped a piece of meat on the floor and while picking it back up, stated that as long you were alone in the kitchen, no one would ever know and the food would be fine to serve to your guests.

Where the five second part originated from is a little hazy, but regardless of how it got started there are a few studies on record testing the issue. The first published study used gummy bears and cookies and found that after dropping them on the floor, five seconds, was all it took for bacteria from the floor to be transferred onto the food.

This study, however, did not report how much actual bacteria was transferred and led to the most recent study in which researchers inoculated squares of tile, carpet and wood with Salmonella. They then dropped pieces of bologna and bread on the surfaces for five, 30 or 60 seconds and measured the amount of bacteria on the food.

As stated in the article, what they found was that the amount of bacteria transferred to either kind of food did not depend much on how long the food was in contact with the contaminated surface – whether for a few seconds or for a whole minute. Instead, overall the amount of bacteria on the surface mattered more.

Based on these findings it appears that the issue is less how long your food languishes on the floor but rather how infested with bacteria that patch of floor happens to be. The researchers also found that the kind of surface made a difference as well. For example, carpets seem to be slightly better places to drop food than wood or tile. When carpet was inoculated with Salmonella, less than 1% of the bacteria was transferred. However, when the food was dropped on tile or wood, 48% to 70% of bacteria transferred.

So should you eat food that has fallen the floor?

From a food safety standpoint, the article states that out of the millions or more cells on a surface, 0.1% of them are still enough to make you sick. Also, certain types of bacteria are extremely virulent, and it takes only a small amount to make you sick. For example, 10 cells or less of an especially virulent strain of E. coli can cause severe illness and death in people with compromised immune systems.

However, the chance of these bacteria being on most surfaces is very low. In addition, when you add in the other areas—such as your hands and the utensils you use to eat your food—bacterial transfer is occurring in these instances anyway.

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 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.

For more information, click here.

Comments are closed.