A while ago I read about a new scientific paper from Clemson University that struck me as both pioneering and hilarious.

It reinforced my belief how cockamamie that fabled urban myth of the “5 second rule” truly is.

Hey, my food handler’s card is current.

Ever dropped a cookie on the floor, yelled “five-second rule,” then quickly picked it up and popped it into your mouth? The assumption is that five seconds is not a long enough time for your food to pick up harmful bacteria.

The exact origin of this urban legend is unknown, but supposedly, Genghis Khan was the first to make such a claim, specifying a lenient 12 to 20 hour period for food left on the ground to remain safe.

The fast food industry also has been credited with the “rule,” supposedly to help minimize food waste.

Whatever its origin, the “5 second rule” has become a readily accepted practice by young and old alike, especially to rationalize the eating of sweet foods  that have fallen to the ground.

“Oops, dropped my popsicle. Five second rule!”
(Proceeds to pick up dirty-ass rocket pop and suck the lint off of it)

In fraternity houses, this rule is the 1.5 second rule. Rule is invalid in the restroom

Accompanied by six graphs, two tables and equations whose terms include “bologna” and “carpet,” a Clemson University research team made a thorough microbiological study of the five-second rule: the idea that if you pick up a dropped piece of food before you can count to five, it’s O.K. to eat it.
We’ve all heard about the rule from children and thought it was just a way of having fun at snack time and lunch. We’re reminded about germs on food whenever there’s an outbreak of E. coli or salmonella, and whenever we read the labels on packages of uncooked meat.

But we don’t have much occasion to think about the everyday practice of retrieving and eating dropped pieces of food.

Microbes are everywhere around us, not just on floors. They thrive in wet kitchen sponges and end up on freshly wiped countertops.

The pioneer of five-second research is Jillian Clarke, a high-school intern at the University of Illinois in 2003.

Among Clarke’s findings:
–Seventy percent of women and 56 percent of men are familiar with the 5-second rule, and most use it to make decisions about tasty treats that slip through their fingers.
–Women are more likely than men to eat food that’s been on the floor.

–Cookies and candy are much more likely to be picked up and eaten than cauliflower or broccoli.
–And, if you drop your food on a floor that does contain microorganisms, the food can be contaminated in 5 seconds or less.

Clarke conducted a survey and found that slightly more than half of the men and 70 percent of the women knew of the five-second rule, and many said they followed it.
She did an experiment by contaminating ceramic tiles with E. coli, placing gummy bears and cookies on the tiles for the statutory five seconds, and then analyzing the foods. They had become contaminated with bacteria.

For performing this first test of the five-second rule, Clarke was recognized by the Annals of Improbable Research with the 2004 Ig Nobel Prize in public health.

It’s not surprising that food dropped onto bacteria would collect some bacteria. How many bacteria does it collect more as the seconds tick by?
Prof. Paul L. Dawson and his colleagues at Clemson have now put some numbers on floor-to-food contamination. Their bacterium of choice was salmonella; the test surfaces were tile, wood flooring and nylon carpet; and the test foods were slices of bread and bologna.
First the researchers measured how long bacteria could survive on the surfaces. They applied salmonella broth in doses of several million bacteria per square centimeter, a number typical of badly contaminated food.

After 24 hours of exposure to the air, thousands of bacteria per square centimeter had survived on the tile and wood, and tens of thousands on the carpet. Hundreds of salmonella were still alive after 28 days.

Dawson and colleagues then placed test food slices onto salmonella-painted surfaces for varying lengths of time, and counted how many live bacteria were transferred to the food.
On surfaces that had been contaminated eight hours earlier, slices of bologna and bread left for five seconds took up from 150 to 8,000 bacteria. Meat Left for a full minute collected about 10 times more than that from the tile and carpet, though a lower number from the wood.

What do these numbers tell us about the five-second rule? Quick retrieval does mean fewer bacteria, but it’s no guarantee of safety.

True, Clarke found that the number of bacteria on the floor at the University of Illinois was so low it couldn’t be measured, and the Clemson researchers resorted to extremely high contamination levels for their tests.

But even if a floor — or a countertop, or wrapper — carried only a thousandth the number of bacteria applied by the researchers, the piece of food would be likely to pick up several bacteria.
The infectious dose, the smallest number of bacteria that can actually cause illness, is as few as 10 for some salmonellas, fewer than 100 for the deadly strain of E. coli.

Of course we can never know for sure how many harmful microbes there are on any surface.

But we know enough now to formulate the five-second rule, version 2.0: If you drop a piece of food, pick it up quickly, take five seconds to recall that just a few bacteria can make you sick, then take a few more to think about where you dropped it and whether or not it’s worth eating.

“At least, wash it first,” says Ruth Frechman, M.A., R.D., spokeswoman for the American Dietetic Association. “Bacteria are all over the place, and 10 types, including E. coli, cause food borne illnesses, such as fever, diarrhea, and flu-like symptoms.”

Food borne illnesses can have varying onset, ranging from 24 hours to a week. So, if the food you picked up and ate last Wednesday was responsible for sidelining you over the weekend, you probably wouldn’t even associate the two events.

Robert Romaine first heard the five-second rule when he became a San Diego County health inspector, a job he held for more than 25 years. “I don’t think anyone in the restaurant business really believes the five-second rule, but restaurant operators are concerned about the bottom line. So they might be reluctant to throw away food, even though they know the risk.”

Romaine says violators are unlikely to get caught. “When a health inspector is in a restaurant, everyone is on their best behavior.”

“If the food is dry, and there’s no stickiness to it, it’s less likely that bacteria will stick to it but in most cases we’re talking about a $20 steak or a piece of fish that’s not dry,” Romaine said “If it’s dry food, then we’re just talking about filth, like hair or whatever is on the soles of shoes.”

Until further studies are done, there’s no consensus on how safe it is to eat dropped food. Food borne illnesses are not serious for most of the 76 million Americans who contract them every year.

But, according to the web site of the CDC’s National Center for Infectious Diseases, it’s estimated that of those cases, 300,000 people are hospitalized, and 5,000 die. Most deaths occur among susceptible populations that include small children, the elderly, and people with weakened immune systems.

For those who don’t read, this myth was busted on the Discovery Channel’s “Mythbusters.” 


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