Don’t you put it in your mouth!

Trisha Daigle, The Baron (University of New Brunswick, Saint John)

SAINT JOHN (CUP) — You’ve most likely seen it happen; odds are you’ve even done it. You’re munching away on your favourite snack when all of a sudden a good-sized chunk of it falls to the floor. Do you declare the five-second rule and dive down to retrieve it and continue eating? Too late.

But what about the 10-second rule?

As kids, many of us have heard of such “rules,” ones that enable us to save our precious food that has fallen to those dirty surfaces. A 2003 survey conducted by the University of Illinois found that 70 per cent of women and 56 per cent of men are familiar with these rules, with most respondents confessing to partaking in such behaviour on more than one occasion in their lifetimes. But how true is this rule? Is it really safe for us to be eating off the floor?

Before even thinking about the food, think about the surfaces your food touches. Surfaces such as floors are covered in things such as dust, dead skin particles, and hair. Would you eat your supper if you found a dust bunny and a piece of hair in it? Besides all of this appetizing particulate matter, the presence of viruses that were coughed or exhaled onto the surface just prior to dropping the food could also be present, even for a brief time on the surfaces around you.

It may seem obvious that some areas, such as kitchens and bathrooms, have a great deal more bacteria on their surfaces, but we travel from place to place transporting these microbes on our feet and hands, often without a second thought. There are 10 types of bacteria that cause food-borne illnesses, and these bacteria can survive for over a month in some conditions. Research at U.S. universities shows that detectable numbers of bacteria on most surfaces are surprisingly low. In fact, they are often undetectable. There is, however, a continued risk with even these surfaces, as it can take as few as 10 of some strains of bacteria to cause illness.

In 2007, Paul Dawson and his colleagues at Clemson University in South Carolina evaluated the well-known five-second rule to determine its legitimacy. They contaminated wood, tile flooring, and carpet with salmonella and left it for eight hours then “dropped” various foods, such as bread and bologna onto it to determine the quantity of transfers of bacterium. Wood transferred fewer bacteria than other flooring types. But nonetheless, when left for five seconds food picked up thousands of bacteria and when left for a minute picked up 10 times more. These results, however, involved higher than normal levels of bacteria on the surface than normally found on most surfaces.

Researchers from Connecticut College performed a similar experiment, dropping apples and Skittles onto the college dining hall floor. They found that it took at least 30 seconds or more for bacteria to colonize on the moist, porous apple slices and longer than a minute (up to five minutes in some instances) on the dry, nonporous Skittles. They found that more aggressive bacteria such as E. coli colonized much more quickly, in under five seconds.

So, from this research, we can see that heavily contaminated surfaces can transfer bacteria to your food faster than you can pick it up. In some instances, it does take a long time for bacteria to colonize depending on the quantity of bacteria present on the surface.

Some people now say that the five-second rule can be extended to 30 seconds or even one minute for dry foods. But, when it takes as few as 10 of some strains of bacteria to make you sick, and there are people sneezing and coughing out viruses all around you, do you really want to take that chance and put it in your mouth?