Is there truth behind the '5-second' rule on food?

January 24, 2011 7:47 am 

By Maybelline M. Dy

MANILA, Jan. 22 — Countless times have a number of people accidentally dropped their food on the floor, picked it up quickly, dusted it off, and ate it.

"Five-second rule!" they must have said triumphantly, albeit silently. In the Philippines, "Wala pang five seconds!" is what's often heard.

The five-second rule states that it's still safe to eat food that has been dropped on the floor if it is picked up within five seconds.

For sure there have been one too many debates over the validity of this rule. Some believe and follow it, some don't.

For one thing, determining exactly when the "five- second" rule starts and ends is a problem since not all people always carry a stopwatch with them.

There actually have been a number of scientific studies conducted independently by different researchers to find out if there is any grain of truth to this rule.

In 2003, a pioneering research was done by then high school student Jillian Clarke. She conducted a study about the five-second rule as an intern at the Hans Blaschek Laboratory in the University of Illinois. She did the research under the supervision of Meredith Agle who was at that time a candidate for a doctoral degree in the said university.

Clarke, then a senior student at the Chicago High School for Agricultural Sciences, found out that food could be contaminated within five seconds or less if it hit the floor that already contained germs.

On one side of the study, Clarke and Agle found out that the university floors from which they took some microbial samples were actually clean.

"We didn't even find a countable number of bacteria on the floor. We thought we might have made a mistake, so we tried again with the same result," she said in an article by Phyllis Picklesimer, also from the University of Chicago.

Suffice it to say, if the floors have barely countable microorganisms, it would take a longer time to contaminate food that has hit the ground.

For the groundbreaking study, Clarke got an Ig Nobel award at Harvard University in 2004.

Another study was conducted by Professor Paul L. Dawson, PhD, at Clemson University in 2007. He and his students were able to publish the results of their study in the Journal of Applied Microbiology.

According to their research, bacteria can actually be transferred from surfaces like tabletops and floors in five seconds. They used bologna and bread as food samples and dropped them to surfaces that have been contaminated with salmonella bacteria.

In addition, they found out that some bacteria can survive on dry surfaces even after a long period of time, thus, still viable to contaminate food.

Dawson said "the five-second rule is not an accurate guide when it comes to eating food that has fallen on the floor."

To shed more light regarding the five-second rule, two senior university students from Connecticut College did some experiments in 2007 involving apple slices and Skittles candies.

Molly Goettshe and Nicole Moin, both cell and molecular biology students at that time, said they designed their experiment "to test the rule in an everyday environment." They dropped their food samples on the floors of their university's dining hall and student bar.

Results showed that there were no bacteria present on the food after 30 seconds. It took one minute for the apple slices to be tainted with bacteria, and five minutes for the Skittles candies.

At first glance, the outcome of the studies seem to be in conflict with one another. If a closer look is taken, however, the results are actually synergistic. University floors have been found to have low levels of germs, thus, it would take longer than five seconds for bacteria to contaminate food (especially dry food). It was also concluded that for surfaces that were already tainted with germs, it would take less than five seconds to contaminate food. Dry foods take longer to contaminate than wet foods.

One cannot tell for sure, though, that a particular surface is clean or already contained germs. There is so much that the naked eye can't see.

"Err on the side of safety," said Ruth Frenchman, spokeswoman for the American Dietetic Association. If food has fallen to the ground, even if the ground looks clean, it is best not to pick it up for consumption.

Robert Romaine, a former health inspector in San Diego COunty, now a food safety consultant and culinary instructor, said, "We teach students that any surface, especially floors, should not be considered clean, and any food that comes in contact with it is trash."

If you are able to beat the five-second deadline, think longer before you put the food in your mouth. Better yet, just throw it out. "Wala pang five seconds!" can get you sick just as quickly. (PNA Feature)

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