Wednesday, May 16, 2007


On Michael Smerconish's AM talk radio program this morning, he talked with a Clemson University professor who published an article last summer on the "five second rule," that is, the rule that if you retrieve the food you dropped on the floor within five seconds, you can still eat it.

He cleaned, and then applied a salmonella-laden solution to, three common flooring materials: ceramic tile, hardwood flooring, and a tightly woven carpet. He selected salmonella because it is the most prevalent cause of food-borne illness. Then he and his students dropped bologna and white bread onto the three surfaces to test the speed at which the salmonella was absorbed by the food products. They found that contamination occurred at a hazardous level almost immediately, with harmful levels of contamination in the first few seconds. They found no significant additional contamination after 60 seconds. They also found, to the professor's surprise, that salmonella bacteria persisted on the uncleaned surfaces for 28 days, and that contamination was more substantial on the hard surfaces than on the carpet, due to the salmonella solution being absorbed more deeply into the carpet, leaving less of it on the surface to contact the food.

The professor said he has also recently tested "double dipping" and found significant levels of bacteria transfer in the double dip compared to single dipping, proving George Costanza wrong. That research is not yet published.


Dude said...

Our tax dollars at work. My kids know of the five second rule but they still have no idea how I judge the worthiness of food that has fallen to the ground. They are smart enough to ask me if it is still okay to eat and they silently pray for the go-ahead but they must think that the answer is given to me from a higher power as they cannot discern the pattern.

In reality, my decision is weighted by two main factors - the cleanliness of the floor and the absorption properties of the fallen food. If the floor has been recently cleaned and the morsel is an M&M for example, then the five second rule is in effect and permission is granted to pop it in the mouth. If the M&M fell out of someone's mouth however, then it is now bound for the trash can as it is sure to have picked up something nasty the moment it contacted the floor.

The most common detritus on our kitchen floor, even when clean, is hair and dust, which can easily be removed with a point blank blow so long as the food item is not wet nor sticky. If a piece of cookie has fallen and there are no more cookies then its value rises and I don't want the child to throw a fit so I will usually give the kid the go ahead by saying "just blow on it." I think Mason has come to believe that blowing on fallen food can remove even salmonella, since anything that falls from his hand, plate, or mouth gets repeatedly blown on in hope to sway my opinion as I render judgment.

Tom said...

I’ve almost always had a dog and that simplifies the procedure quite a bit. First the item falls. Then the dog is called. Anything made from meat or cheese usually gets the nod immediately. A piece of bread or a potato chip will get a sniffing or two first and eventual digestion. On those items the dog will not eat; raw carrots, iceberg lettuce etc, the 5 second rule is long gone before the dog makes up his mind. Those times I didn’t have a dog, I usually just threw the item away because the floor was always something I associated with dog spit.

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