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Today in the cafeteria my friend dropped a chicken wing on the floor and immediately picked it up and ate it. Afterward he claimed that the chicken wing was still safe to eat if it was consumed within 5 seconds after being on the floor. He said that it's the "five second rule". Is this rule safe to follow?

Sklivvz
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James
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    It depends on the floor (if the floor is covered in shit then it's probably not safe, but if the floor is sufficiently clean then it probably is). When I was growing up, picking it off the floor *quickly* was to get it before the dog did. – ChrisW May 16 '11 at 06:35
  • what I know is "two seconds rule"!! not "five" :P – Sufendy May 16 '11 at 06:45
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    mythbusters did this one. It was highly entertaining – Monkey Tuesday May 16 '11 at 06:46
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    As Monkey said: Mythbusters tested this and came to the understandable result that the amount of time the foot lies on the ground has no reasonable influence on the amount of bacteria it gets in contact with. In other word: Direct after the food hit the ground it is already "contaminated". Waiting 1, 5 or 10 seconds before picking it up didn't made any real difference. – Martin Scharrer May 16 '11 at 10:09
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    I thought it was a 'thirty second rule' - no wonder I am always off sick :-) – Matt Wilko May 16 '11 at 11:01
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    I'm pretty sure the purpose of the 5-second rule is to avoid social- or even self-disapproval for doing the icky thing of eating food off the floor. Assuming a relatively clean floor, it's really not that dangerous. But people think it's gross and it's looked down on. The solution? The 5-second rule, where you can salvage your food while saving face socially. I doubt many people really believe the 5-second rule is a valid means to avoid bacteria, but we all agree to pretend it does in order to not waste food. – Brian Schroth May 16 '11 at 12:56
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    In college it's the "48 hour rule" – Travis Christian May 16 '11 at 18:03
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    Here is a simple experiment to (dis)prove whether the five-second rule is wrong: Take some tissue, wet it a little bit, then crample it into a ball (this simulates food), scramble some pepper on the floor (this simulates dusts, most powdery stuff works, but it's best if it had contrasting color with the tissue). Drop the tissue on the pepper, leave it for 1 to 10 seconds, and see how much of the pepper sticks. – Lie Ryan May 16 '11 at 12:08
  • *Food hits floor* Little germs: GET IT!!! King Germ: NO! We must wait 5 seconds! – wim Oct 28 '12 at 23:47
  • May add this video to confutation of the claim? http://www.youtube.com/watch?v=rYXdsOEWBj0&feature=g-subs – Duralumin Nov 30 '12 at 19:24
  • ... seems that the rule is valid if it's the 1-femtosecond rule. – Duralumin Nov 30 '12 at 19:30

3 Answers3

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Jillian Clarke researched this in 2003 when she was a high school science intern at the University of Illinois.

Among Clarke's findings:

  • 70% of women and 56% 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 was awarded the 2004 IG Nobel Prize in Public Health for her work.



Food Scientist Paul Dawson at Clemson University also looked into it.
His findings were published in the Journal of Applied Microbiology:

Three experiments were conducted to determine the survival and transfer of Salmonella Typhimurium from wood, tile or carpet to bologna (sausage) and bread.

In the case of the 5-second-rule we found that bacteria was transferred from tabletops and floors to the food within five seconds, that is the 5-second-rule is not an accurate guide when it comes to eating food that has fallen on the floor.



The MythBusters also busted the 5-second-rule:

Even if something spends a mere millisecond on the floor, it attracts bacteria. How dirty it gets depends on the food's moisture, surface geometry and floor condition — not time.

Here is the video.

Oliver_C
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    +1 - Fantastic, comprehensive answer. A worthy field of study for an Ig Nobel Prize too. :) –  May 16 '11 at 11:45
  • lol @ Nobel Prize for this. – Kevin Peno May 16 '11 at 17:26
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    @Kevin: The IG Nobel Prize is a negative prize and to the real Nobel Prize like the Golden Raspberry to the Oscar. – Martin Scharrer May 16 '11 at 19:07
  • @Martin, totally ignored the IG part when I read the first time *facepalm* – Kevin Peno May 16 '11 at 20:30
  • @Kevin: I had to read it twice as well ;-) – Martin Scharrer May 16 '11 at 20:32
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    +1 For finding an Ig laureate in the field _(and for being the image master)_. – Rusty May 16 '11 at 22:48
  • Ironically, candy-on-floor is "worse" than broccoli-on-floor, as the sticky sugar will pick up more particles than the broccoli. – Mateen Ulhaq May 16 '11 at 23:17
  • The mythbuster's video takes the day. – Kzqai May 17 '11 at 15:59
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    @Martin IG Nobel is not at all a negative prize. – Stefan Aug 28 '12 at 16:15
  • +1 for @Stefan and also, Oliver, you shouldn't end with the MythBuster quote in this case. The focus should all go to the ig nobel quote. The TL;DR; should be **for a clean floor and non-sticky food, amazingly enough the 5-second rule does apply** - but it's a much better healthy rule to *never eat anything that can easily get contaminated with fatal bacteria, not just what falls on the floor*, which brings me to a much better rule of thumb. Just read, get well informed and remember asking yourself: **is this piece of food worth risking my health?** – cregox Dec 02 '15 at 09:32
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While perhaps not a real answer for the question, I would like to highlight some grass roots skepticism that a question such as this can be the basis for. An actual scientific study on this phenomenon/saying was conducted by a High School senior. See, ANYONE can do real science, and it may even prove interesting to folks.

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."

Just remember, if it's cake on the floor, it's a lie!

Community
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Larian LeQuella
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http://www.boston.com/business/ticker/2007/05/5second_dropped.html

it is, in fact, 30 seconds for wet food, or much longer for dry food, according to this study

Russell Steen
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bleh
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  • The other study, whose results differ from the one you reference, seems a bit sounder methodologically – Lagerbaer May 17 '11 at 00:20
  • [Here](http://aspen.conncoll.edu/news/3464.cfm) is the original article, and here is an [ABC News Video](http://abcnews.go.com/Video/playerIndex?id=3269384). It seems like the methodology is the same: drop food, wait various times, swab the food, cultivate bacteria. – Oliver_C May 17 '11 at 00:29
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    Please expand this in a full answer. Link to the studies, provide citations, &c. Are the studies reliable, yes? no? – Sklivvz Aug 25 '12 at 11:33