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“5-second rule” of urban legend found to have real basis

March 10, 2014
Courtesy of Aston University
and World Science staff

An ur­ban leg­end hold­ing that food re­mains use­a­ble af­ter be­ing dropped on the floor—as long as it’s pick­ed up with­in five sec­onds—has a real ba­sis, re­search finds.

Folk­lore claims that many peo­ple use the rule, not nec­es­sarily that it really works. It’s sup­posedly a guide­line that res­tau­rant work­ers, for ex­am­ple, fol­low to save them­selves trou­ble rath­er than pro­tect their cus­tomers.

Sur­pris­ing­ly, though, a study finds that it does work.

Food pick­ed up just a few sec­onds af­ter be­ing dropped is less likely to con­tain bac­te­ria than food left for a long­er time, ac­cord­ing to re­search car­ried out at As­ton Uni­vers­ity in Bir­ming­ham, U.K.

Mi­cro­bi­ol­o­gist An­tho­ny Hil­ton and his fi­nal year bi­ol­o­gy stu­dents mon­i­tored the trans­fer of the com­mon bac­te­ria Esch­e­rich­ia coli and Staph­y­lo­coc­cus au­re­us from a va­ri­e­ty of in­door floor types (car­pet, lam­i­nate and tiled sur­faces) to toast, pas­ta, bis­cuit and a sticky sweet when con­tact was made from 3 to 30 sec­onds. 

The study found that bac­te­ria were likely to trans­fer to moist foods mak­ing con­tact for more than 5 sec­onds. Bac­te­ria was al­so more likely to trans­fer from lam­i­nated or tiled sur­faces rath­er than car­peted.

“Con­sum­ing food dropped on the floor still car­ries an in­fec­tion risk as it very much de­pends on which bac­te­ria are pre­s­ent on the floor at the time; how­ev­er the find­ings of this study will br­ing some light re­lief to those who have been em­ploy­ing the five-second rule for years, de­spite a gen­er­al con­sen­sus that it is purely a myth. We have found ev­i­dence that trans­fer from in­door floor­ing sur­faces is in­credibly poor with car­pet ac­tu­ally pos­ing the low­est risk of bac­te­ri­al trans­fer on­to dropped food,” Hil­ton said.

The researchers al­so sur­veyed peo­ple about their be­liefs re­gard­ing the rule. 

“Our study showed sur­pris­ingly that a large ma­jor­ity of peo­ple are hap­py to con­sume dropped food, with wom­en the most likely to do so. But they are al­so more likely to fol­low the five-second rule, which our re­search has shown to be much more than an old wives’ tale,” Hil­ton said.

The sur­vey found that 87 per­cent of peo­ple sur­veyed said they would eat food dropped on the floor, or al­ready have done so. They al­so found that 55 per­cent of those who would, or have, eat­en dropped food are wom­en.


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An urban legend holding that food remains useable after being dropped on the floor—as long as it’s picked up within five seconds—has a real basis, research finds. Folklore claims that many people use the rule, not necessarily that it really works. It’s supposedly a guideline that restaurant workers, for example, follow to save themselves trouble rather than protect their customers. Surprisingly, though, a study finds that it does work. Food picked up just a few seconds after being dropped is less likely to contain bacteria than if it’s left for longer periods of time, according to the findings of research carried out at Aston University in Birmingham, U.K. Microbiologist Anthony Hilton and his final year biology students monitored the transfer of the common bacteria Escherichia coli (E. coli) and Staphylococcus aureus from a variety of indoor floor types (carpet, laminate and tiled surfaces) to toast, pasta, biscuit and a sticky sweet when contact was made from 3 to 30 seconds. The study found that bacteria were likely to transfer to moist foods making contact for more than 5 seconds. Bacteria was also more likely to transfer from laminated or tiled surfaces rather than carpeted. “Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor at the time; however the findings of this study will bring some light relief to those who have been employing the five-second rule for years, despite a general consensus that it is purely a myth. We have found evidence that transfer from indoor flooring surfaces is incredibly poor with carpet actually posing the lowest risk of bacterial transfer onto dropped food,” Hilton said. The Aston team also surveyed people about their beliefs about the five-second rule. “Our study showed surprisingly that a large majority of people are happy to consume dropped food, with women the most likely to do so. But they are also more likely to follow the five-second rule, which our research has shown to be much more than an old wives tale,” Hilton said. The survey found that 87% of people surveyed said they would eat food dropped on the floor, or already have done so. They also found that 55% of those that would, or have, eaten food dropped in the floor are women.