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UK Study Lends Credence to ‘Five-Second Rule’

Apparently, food picked up just a few seconds after being dropped is less likely to contain bacteria than if it is left for longer periods of time, according to the findings of research carried out at Aston University’s School of Life and Health Sciences in Birmingham, England.

The findings suggest there may be some scientific basis to the “five-second rule” – the urban myth about it being fine to eat food that has only had contact with the floor for five seconds or less. Although people have long followed the five-second rule, until now it was unclear whether it actually helped.

The study, undertaken by final-year biology students and led by Anthony Hilton, professor of microbiology at Aston University, 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 three to 30 seconds.

The results showed that:

  • Time is a significant factor in the transfer of bacteria from a floor surface to a piece of food, and
  • The type of flooring the food has been dropped on has an effect, with bacteria least likely to transfer from carpeted surfaces and most likely to transfer from laminate or tiled surfaces to moist foods making contact for more than five seconds.

Professor Hilton said: “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.”

The Aston team also carried out a survey of the number of people who employ the five-second rule. The survey showed that:

  • 87 percent of people surveyed said they would eat food dropped on the floor, or already have done so.
  • 55 percent of those who would, or have, eaten food dropped in the floor are women.
  • 81 percent of the women who would eat food from the floor would follow the five-second rule.

Professor Hilton added: “Our study showed that a surprisingly 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.”

© Food Safety News
  • Carl Custer
  • John

    University of Illinois and Clemson University in the U.S. have already conducted these studies. A thorough literature review, or even a quick Google search, is always the first place to start in any experiment prior to allocation of labor and materials.

    http://www.nytimes.com/2007/05/09/dining/09curi.html?_r=0

  • Joepalooka1

    now if we can just cause the public at large and the self-styled, so-called professionals to more often put into context the supposed risks that abound (yeah right, that toilet seat is cleaner than your computer keypad :-)

  • flame

    Drop your peeled banana(or any other unwrapped food of your choice) on the subway floor, train station floor, public elevator floor, cruise ship floor, airplane floor, airport floor, movie theater floor, the stairs/and/or landing of any high traffic public building, the hospital cafeteria floor. Hope the 5 second rule applies to you unsanitary floor lickers.

  • the germ guy

    As a former public health food facility inspector, professor of college level food microbiology with food sampling training and lab analysis and consultant to the food service industry, it confounds me why people are so enamored with this flagrant and obvious form of food contamination. I have followed this discussion (and “the studies”) for years. What everyone is missing is that when a food item hits the floor, it is the physical texture of that product (i.e. is it wet, dry, sticky, etc) and the microbes it directly encounters that matter as to what contaminants will adhere and pose a health concern, not how long it lays on the floor. Microbes do not have legs and crawl toward fallen food as this argument seems to imply. Additionally I have tremendous problems with the so called “studies” that want to reassure us that all is well with food if promptly retrieved by some “magic” no. of seconds. To adhere to accepted science guidelines the design of the experiment would have to include foods of many textures with various pH values, anti-microbial additives etc. as well as floor surfaces being inoculated with a representative array of microbes that one can recover from floors in restrooms, fast food playlands, theater lobbies, restaurant kitchens and so on. To merely lay down some E. coli and see if some stuck to a food is not hard science. Finally, what no one ever discusses is what about the viruses that are on the floor? I find it impossible to believe that no one will encounter norovirus on a cruise ship floor. In conclusion, as I tell my students, if food hits the floor, its out the door.

  • Don Schaffner

    Let’s not forget this is unpublished, and not peer reviewed.

    Science by press release is not science.

  • I.Popoff

    Bacterial microbes are not the only concern. What if your food landed on the egg of a parasitic worm, such as the raccoon roundworm. Look it up, this is something you don’t want. People don’t realize the crap they track into their homes on the soles of their shoes.

  • Hachachacha

    I find it surprising that women tipped the scales in observing the 5 second rule. I’m figuring it’s because most men don’t even worry about 5 seconds and will eat food no matter how long it’s been on the floor, LOL. Seriously it amazes me how little some men know about cleanliness. Most of them don’t even wash their hands after going to the bathroom. Perhaps the women observing the 5 second rule are the ones who clean the floor and know more about how clean/unclean it is.