The myth.

According to a food science study conducted by experts at Urbana-Champaign, 70% of women and 56% of men are familiar with the five-second rule.  For those of you that aren’t, the Five Second Rule basically states that if you drop something edible on the floor you have only five seconds to pick it up before it’s crawling with icky germs.  Pick it up within the five seconds and it’s safe to eat.  The origin of this myth is unknown, but nevertheless, people around the world follow it.  This brings us to our myth of the week: Is food really safe to eat if it’s picked up off the floor within five seconds?

The truth.

Medical experts agree that there are several factors that determine how safe a food is to eat when it’s picked up off a floor.

• First, the type of food that is dropped will determine germ adherence.  If it’s something sticky or wet such as ice cream, odds are you’ll be out of luck regardless of how quickly you pick it up.  Cookies and crackers, on the other hand, are less likely to pick up any bacteria lurking on a standard clean floor.
• The second thing to consider is the surface on which the food is being dropped.  According to Dr. Carroll and Dr. Vreeman from the Indiana University School of Medicine food doesn’t tend to pick up many germs when it hits carpet, but be sure to watch out for carpet fuzz.  Drop your food on tile or wood floor and you are likely to pick up a large amount of bacteria.
• Third, how virulent or infectious are the germs on the floor?  An infectious does is the smallest number of bacteria needed to cause illness.  For example, to become sick from salmonella, all it takes is 10 bacterium.  Fewer than 100 E. coli bacterium can make you deathly ill as well.  If you drop food on a floor contaminated with harmful bacteria with a low infectious dose, your chances of becoming ill are much greater.

But does food collect more bacteria as it sits?  Professor and Food Scientist Paul Dawson at Clemson University put this portion of the five second rule to the test.  His food of choice was bologna sandwiches dropped on tile, wood and nylon carpet contaminated by salmonella. Sandwiches left on the surfaces collected 150 to 8,000 bacteria.  If they were left for a full 60 seconds, ten times more bacteria were found.  Read the details of this fascinating paper in the Journal of Applied Microbiology.

The caveat.

As a general rule of thumb,  if you drop any food on a floor (or counter for that matter) that is already contaminated with germs like E. coli, it doesn’t matter how quickly you pick it up.  You’ll be consuming E. coli in some capacity along with your tasty snack.  In 2003 intern Jillian Clarke of the University of Illinois conducted a five-second rule test by inoculating tile with E. coli and dropping gummy bears and cookies. The result?  Contaminated gummy bears and cookies after five seconds.  She tested this on typical public floors too but found the floors to contain so little bacteria that they couldn’t even be counted. Unfortunatley in the real world, we never know what type of microscopic germs are lurking on floors.  That’s a chance you’ll just have to take if you decide to eat off the floor.

In conclusion, this is a tricky myth.  Food that is dropped for five seconds on your typical floor is safe to eat if the floor is generally clean and your food isn’t too moist.  Food that is dropped on a bacteria-infested floor is going to pick up bacteria, and the longer you wait to pick it up, the worse the problem will be.  Food, germs and floors…busted!