In households, restaurant kitchens, and almost anywhere people prepare or
consume food, you'll occasionally hear someone call out "five-second
rule." Whether it's uttered as a way for the speaker to let others know
he's civilized, as an excuse to salvage expensive food, or as an incantation to
ward off sickness, the meaning is the same: If food hits the floor and you
snatch it up in less than five seconds, it's safe to eat."
Is the food really safe? Or should we throw it away or wash it off? WebMD
talked to experts to find out what you should consider before swallowing this
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Yes, someone really has conducted a scientific study of the five-second
rule. It was the project of high school senior Jillian Clarke during a six-week
internship in the food science and nutrition department at the University of
Illinois at Urbana-Champaign. Meredith Agle, then a doctoral candidate,
supervised the study.
"Jillian swabbed the floors around the University in the lab, hall,
dormitory, and cafeteria to see how many organisms we could isolate," Agle
tells WebMD. "We examined the swabs, and there were very few
microorganisms. That surprised me. I told her to do it again."
The results were the same. Agle has since earned her doctoral degree and is
a scientist in new product development for Rich Foods in Buffalo, N.Y. "I
think the floors were so clean, from a microbiological point of view, because
floors are dry, and most pathogens like salmonella, listeria, or E. coli can't
survive without moisture."
To control the study, cookies and gummi bears were placed on both rough and
smooth sterile tiles covered with measured amounts of E. coli. "We did see
a transfer of germs before five seconds," Agle tells WebMD. "We were
dealing with a large number of cells."
All bets are off when it comes to carpet, damp floors, gum, or ice cream, as
these were not included in the study.
Clarke also conducted a survey in which 70% of women and 56% of men said
they were familiar with the rule. Women were more likely to invoke it. Not
surprisingly, people are inclined to eat dropped cookies and candy more often
than dropped broccoli and cauliflower.
For her work, Clarke was awarded an Ig Nobel prize in 2004 at Harvard
University. Ig Nobel prizes recognize "research that first makes you laugh,
then makes you think." Also honored at the ceremony was the inventor of