Five-second rule: Difference between revisions

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{{short description|Western cultural food hygiene myth}}

{{dablink|For an obsolete rule in ice dancing, see [[Ice dancing]]. For estimating the distance to a lightning strike, see [[Thunder#Calculating distance|Thunder]].}}

{{for|the basketball rule|Five-second rule (basketball)}}

{{unreferenced|article}}

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The '''five-second rule''' is

[[File:Spilled_strawberries.jpg|thumb|[[Strawberries]] dropped on the ground. The ''five-second rule'' suggests that if they are picked up within five seconds, it is safe to eat them without rewashing.]]

#a popular [[old wives' tale]], in North America, the United Kingdom, Australia, South Africa and Japan, about eating [[food]] that has been dropped on the [[floor]]

The '''five-second rule''', or sometimes the '''three-second rule''', is a [[food hygiene]] [[urban legend]] that states a defined time window after which it is not safe to eat food (or sometimes to use [[cutlery]]) after it has been dropped on the floor or on the ground and thus exposed to contamination.

#a rule of etiquette regarding occupying a seat which someone else has vacated

While the amount of microbes transferred to a dropped food does increase over time, and in some situations floors may be relatively clean of pathogens, the scientific consensus is opposed to such a general applied rule,<ref>{{cite web |author=Skanulis |first=Leanna |date=2007 |title='5-Second Rule' Rules, Sometimes |url=http://www.webmd.com/a-to-z-guides/features/5-second-rule-rules-sometimes-#1 |access-date=July 10, 2024 |publisher=[[WebMD]]}}</ref> and the origin of the idea is unclear. It is speculated to have originated from legends about [[Genghis Khan]]. It was first mentioned in print in 1995.

The exact number of seconds cited may differ depending on the person invoking the 'rule', or, more conveniently, following the expression n+1 where n represents the number of seconds the food is estimated to have been in contact with a given unclean surface.

==Food ruleHistory ==

[[File:YuanEmperorAlbumGenghisPortrait.jpg|thumb|upright|[[Genghis Khan]] is said to have ruled that food dropped on the floor "could stay there as long as Khan allowed"]]

This rule applies to foods&mdash;particularly solid foods like [[cookie]]s&mdash;that have fallen to the ground. The rule states that any [[germ]]s that can be contracted by grounded food in under five seconds are of such a small amount that they will easily be destroyed by [[gastric acid]], thus causing no harm to the body. The rule provides a convenient rationale for eating food off the floor, and is usually invoked when a group of people are present (as a [[polite fiction]]). Thus, for example, a person might drop a piece of candy and pick it up quickly, tell his friends "five second rule" and then eat the candy.

The origins of the five-second rule are unclear.<ref>{{Cite news |last=Sefton |first=Dru |date=September 29, 2003 |title=Intern Puts Science Behind the Five-Second Rule |url=http://www.newhousenews.com/archive/sefton092903.html |url-status=dead |archive-url=https://web.archive.org/web/20061115101748/http://www.newhousenews.com/archive/sefton092903.html |archive-date=November 15, 2006 |work=[[Advance Publications|Newhouse News Services]]}}</ref> Food scientist Pawl Dawson and microbiologist Brian Sheldon have traced the origins to legends surrounding [[Genghis Khan]] in the 15th century. He is rumoured to have implemented the "Khan Rule" at his banquets. "If food fell on the floor, it could stay there as long as Khan allowed," and the idea was that "food prepared for Khan was so special that it would be good for anyone to eat no matter what."<ref>{{Cite web |last=Mayer |first=Johanna |date=February 20, 2019 |title=The Origin Of 'The Five-Second Rule' |url=https://www.sciencefriday.com/articles/the-origin-of-the-five-second-rule/ |access-date=July 10, 2024 |website=[[Science Friday]] |language=}}</ref>

The first known mention of the myth in modern print was in the 1995 novel ''Wanted: Rowing Coach'' as a "twenty-second rule".<ref>{{Cite OED|term=second|id=7821975804|access-date=July 10, 2024}}</ref>

The five-second rule is seldom invoked in the case of sticky foods, such as ice cream, cold cuts, or jelly beans which have been moistened, particularly if visibly dirty. It is also rarely used in cases of toast [[Toast#Trivia|landing buttered-side-down]]. The five-second rule is rarely applied to other people's food, although many instances have been documented. If a food falls in feces, the five-second rule is never used. The origin of the five-second rule is unknown.

== Research ==

In reality, it is usually safe to eat food from a relatively clean floor (see "Research" below). However, the notion that germs from a dirty floor will not reach food for at least five seconds is false. For this purpose, cleanliness is a matter of bacterial or parasitic contamination rather than visible dirt, although the two often go together. For example, sick people attend hospitals, with the result that a hospital floor which has not been decontaminated properly can appear to be relatively clean, while actually being more contaminated than the dirty street outside.

The five-second rule has received some scholarly attention.<ref>{{Cite news |last=Deardorff |first=Julie |date=August 9, 2010 |title=Capsule: The five-second rule |url=https://www.latimes.com/archives/la-xpm-2010-aug-09-la-he-capsule-20100809-story.html |access-date=July 10, 2024 |work=[[Los Angeles Times]]}}</ref> It has been studied as both a [[public health]] recommendation and a [[sociological]] effect.

=== University of Illinois ===

No data exists for the use of the five-second rule in restaurant kitchens; nonetheless, the practice is thought to enjoy a frequent use by cooks in a hurry. Although the idea of the five-second rule being used in fine dining establishments as an official policy is absurd, its use is not limited to restaurants of lower standards.

In 2003, Jillian Clarke, a high school student during an apprenticeship investigated the rule. She found 56% of men and 70% of women surveyed were familiar with the five-second rule. She also determined that a variety of foods were significantly contaminated by even brief exposure to a tile inoculated with ''[[Escherichia coli|E. coli]]''. On the other hand, Clarke found no significant evidence of contamination on public flooring.<ref name="aces">{{cite news |last= |first= |date=September 2, 2009 |title=If You Drop It, Should You Eat It? Scientists Weigh In on the 5-Second Rule |url=http://news.aces.illinois.edu/news/if-you-drop-it-should-you-eat-it-scientists-weigh-5-second-rule |url-status=dead |archive-url=https://web.archive.org/web/20130727132440/http://news.aces.illinois.edu/news/if-you-drop-it-should-you-eat-it-scientists-weigh-5-second-rule |archive-date=July 27, 2013 |access-date= |work= |publisher=[[University of Illinois College of Agricultural, Consumer, and Environmental Sciences]]}}</ref> For this work, Clarke received the 2004 [[Ig Nobel Prize]] in public health.<ref>{{cite web |title=Winners of the Ig® Nobel Prize |url=http://improbable.com/ig/ig-pastwinners.html#ig2004 |url-status=live |archive-url=https://web.archive.org/web/20090830181439/http://improbable.com/ig/ig-pastwinners.html#ig2004 |archive-date=August 30, 2009 |access-date=July 10, 2024 |website= |publisher=[[Ig Nobel Prize]]}}</ref>

A more thorough study in 2007 using [[salmonella]] on wood, tiles, and nylon carpet, found that the bacteria could thrive under dry conditions even after twenty-eight days.<ref name=":0">{{cite journal |author=Dawson |first1=P |last2=Han |first2=I |last3=Cox |first3=M |last4=Black |first4=C |last5=Simmons |first5=L |date=1 April 2007 |title=Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule |journal=[[Journal of Applied Microbiology]] |volume=102 |issue=4 |pages=945–953 |doi=10.1111/j.1365-2672.2006.03171.x |pmid=17381737 |s2cid=19871846 |doi-access=}}</ref> Tested on surfaces that had been contaminated with salmonella eight hours previously, the bacteria could still contaminate bread and [[Bologna sausage|baloney]] lunchmeat in under five seconds. But a minute-long contact increased contamination about tenfold (especially on tile and carpet surfaces).<ref name="bologna">{{cite news |last=McGee |first=Harold |author-link=Harold McGee |date=May 9, 2007 |title=The Five-second Rule Explored, or: How Dirty Is That Bologna? |url=https://www.nytimes.com/2007/05/09/dining/09curi.html |url-access=subscription |access-date=July 10, 2024 |work=[[The New York Times]]}}</ref>

===Variations===

The five second rule is sometimes called the '''three-second rule''', '''seven-second rule''', '''10-second rule''', or the '''15-second rule''', to some extent depending on locale, the quality of the food involved or the intoxication level of the individual quoting the rule. For example, in [[United States|American]] [[college]] [[dormitory|dormitories]] the '''ten-second rule''' is often quoted as the "drunk version" of the five-second rule.

=== Rutgers University ===

In some instances, if the initial 5 seconds is exceeded, an additional 5 seconds will be administered, and so forth and so on until the dropped food item is retrieved and eaten.

Researchers at [[Rutgers University]] debunked the theory in 2016 by dropping watermelon cubes, gummy candies, plain white bread, and buttered bread from a height of {{convert|5|in|cm|spell=in}} onto surfaces slathered in ''[[Enterobacter aerogenes]]''. The surfaces used were carpet, ceramic tile, stainless steel and wood. The food was left on the surface for intervals of 5, 30 and 300 seconds. The scientists assessed the amount of ''E. aerogenes'' transferred between surface and food. Since bacteria tended to be attracted to moisture, wet food had more risk to have bacteria transferred than dry food. To the surprise of the researchers, carpet transferred fewer bacteria than steel or tile. Wood was hard to pin down as it showed a large variation. "The five-second rule is a significant [[oversimplification]] of what actually happens when bacteria transfer from a surface to food," Donald Schaffner, a Rutgers University biologist and an author of the research, stated in the ''Washington Post'', "Bacteria can contaminate instantaneously."<ref>{{Cite news |last=Guarino |first=Ben |date=September 13, 2016 |title=The 'five-second rule' for eating food? Scientists just demonstrated how gross it is. |url=https://www.washingtonpost.com/news/morning-mix/wp/2016/09/13/the-five-second-rule-for-eating-food-scientists-just-demonstrated-how-gross-it-is/ |access-date=July 10, 2024 |newspaper=[[The Washington Post]]}}</ref>

A pediatrician criticized the study for discounting the danger in consuming food after one touches other surfaces like refrigerator handles, light switches, and wallets, which have been found to be similarly contaminated with bacteria.<ref>{{Cite web |last=Carroll |first=Aaron E. |author-link=Aaron Carroll |date=October 10, 2016 |title=I'm a Doctor. If I Drop Food on the Kitchen Floor, I Still Eat It. |url=https://www.nytimes.com/2016/10/11/upshot/im-a-doctor-if-i-drop-food-on-the-kitchen-floor-i-still-eat-it.html |archive-url=https://web.archive.org/web/20161010110551/https://www.nytimes.com/2016/10/11/upshot/im-a-doctor-if-i-drop-food-on-the-kitchen-floor-i-still-eat-it.html |archive-date=October 10, 2016 |access-date=July 10, 2024 |website=[[The Upshot]] |publisher=[[The New York Times]]}}</ref>

===Idioms===

There are a number of idiomatic expressions used around the world when eating food which is in some way perceived as dirty or hazardous. Some examples:

===Other===

*''O que não mata, engorda'' ([[Portuguese language|Portuguese]]: "If it doesn't kill you, it's fattening").

A 2014 study by biology students at [[Aston University]] in England suggested that there may be a basis for the five-second rule.<ref>{{cite web|url=https://www2.aston.ac.uk/news/releases/2014/march/five-second-food-rule-does-exist/index.aspx|title=Researchers prove the five-second rule is real|website=Aston University}}</ref> Anthony Hilton, head of microbiology at Aston University, indicated in 2017 that food dropped on a seemingly clean floor for a few moments can be eaten with minimal risk.<ref>{{cite news|url=https://www.independent.co.uk/news/science/five-second-rule-food-dropped-floor-germs-scientists-professor-anthony-hilton-aston-university-a7629391.html|title='Five-second rule' for food dropped on the floor approved by germ scientists|author=Ryan Hooper|date=March 15, 2017|access-date=March 15, 2017|publisher=The Independent (UK)}}</ref> According to Hilton, moist foods that are left on the floor for more than 30 seconds are contaminated with 10 times more bacteria than food that has been left on the floor for 3 seconds.<ref>{{Cite web |last=Greenemeier |first=Larry |title=Fact or Fiction?: The 5-Second Rule for Dropped Food |url=https://www.scientificamerican.com/article/fact-or-fiction-the-5-second-rule-for-dropped-food/ |access-date=2023-05-02 |website=Scientific American |language=en}}</ref>

*''Lo que no mata, engorda'' ([[Spanish language|Spanish-speaking countries]]: "If it doesn't kill you, it makes you fatter").

*''Poco veneno, no mata.'' ([[Spanish language|Spanish-speaking countries]]: "A little venom, wont kill.").

*''Min ma joqtolx, isemmen'' ([[Malta]]: "If it doesn't kill you, it's fattening").

*''Quel che non strozza, ingrassa'' ([[Italian language|Italian]]: "If it doesn't choke you, it's fattening").

*''Chancho limpio nunca engorda'' ([[Spanish language|Spanish-speaking countries]]: ("A clean [[pig]] never gets fat").

*''Dreck macht Speck'' (Southern [[Germany]]: A double-meaning, "Dirt makes bacon" or "Dirt makes fat").

*''Dreck reinigt den Magen'' ([[Germany]]: 'Dirt cleans the stomach').

*''Was Dich nicht umbringt, macht Dich stärker'' ([[Germany]]: "If it doesn't kill you, it makes you tougher").

*''Lite skit rensar magen'' ([[Swedish language|Swedish]]: 'Some dirt cleans the stomach').

*''Zand schuurt de maag'' ([[Dutch language|Dutch]]: "Sand scours the stomach").

*''Baat het niet dan schaadt het niet'' ([[Dutch language|Dutch]]: "If it won't benefit you, it won't harm you either.").

*''大菌吃小菌'' ([[Chinese language|Chinese]]: "Big germs (people) eat small germs").

*''不乾不淨,吃了沒病'' ([[Chinese language|Chinese]]: "Occasional germs and dirt will keep you from getting sick.").

*''You'll eat a peck of dirt before you die''

*''Зараза к заразе не пристанет or Zaraza k zaraze ne pristanet'' ([[Russian language|Russian]]: "dirt won't do any harm to a dirty one").

*''Man skal have syv pund skidt om året'' ([[Denmark]]: "You need seven pounds of dirt a year").

*''God made dirt, dirt don't hurt

*''A little floor spice makes every meal nice.

*''Ce qui ne nous tue pas nous rend plus fort'' ([[French]]: "What doesn't kill us makes us stronger").

===ResearchInformal===

The five-second rule was featured in an [[MythBusters (2005 season)#Five-second Rule|episode]] of the [[Discovery Channel]] series ''[[MythBusters]]'', which discovered that there was no significant difference in the number of bacteria collected. The aspects that affect the contamination process is the moisture, surface geometry and the ___location.<ref>{{cite web |last=Conley |first=Ken |date=October 2005 |title=Annotated Mythbusters: Episode 39 Chinese Invasion Alarm, 5 Second Rule |url=http://kwc.org/mythbusters/2005/10/mythbusters_chinese_invasion_a.html |url-status=dead |archive-url=https://web.archive.org/web/20080321030933/http://kwc.org/mythbusters/2005/10/mythbusters_chinese_invasion_a.html |archive-date=March 21, 2008 |access-date=}}</ref>{{Unreliable source?|date=July 2024}} An episode of ''[[Food Detectives]]'' found that bacteria will cling to food immediately.<ref>{{Cite news |last=Hale |first=Mike |date=2008-08-05 |title=Private Eye for the Food Guy: Cuisine Sleuths on the Case |url=https://www.nytimes.com/2008/08/05/arts/television/05food.html |access-date=2025-04-26 |work=The New York Times |language=en-US |issn=0362-4331}}</ref>

A study on the five-second rule was performed by [[Jillian Clarke]], a high school senior, during a seven-week internship at the [[University of Illinois at Urbana-Champaign]] in [[2003]]. Clarke and a doctoral candidate named [[Meredith Agle]] took swab samples from various floors around campus. They then looked at the samples under a microscope and discovered that they did not contain significant amounts of bacteria. The conclusion was that in most cases, dry floors would be safe to eat from.

== References ==

However, Clarke also wanted to test the five-second hypothesis in cases where the floor was known to be contaminated. She therefore spread [[E. coli]] on both rough and smooth floor tiles in a laboratory, placed pieces of [[gummy bears]] and cookies on the tiles for various amounts of time, and then examined the foods under the microscope. All the foods had a significant amount of bacteria after less than five seconds. Her findings therefore disproved the five-second rule.

{{Reflist}}

{{portalbar|Food}}

In the course of her research, Clarke also conducted a survey to sample opinion on the five-second rule. She found that seventy percent of women and fifty-six percent of men were familiar with the five-second rule, and most utilized the rule in their decisions to eat food that had fallen on the floor. She also found that women were more likely than men to use the rule, and that cookies and [[candy]] were more likely to be picked up than [[broccoli]] or [[cauliflower]].

Clarke's work won an [[Ig Nobel Prize]] for Public Health in [[2004]].

The five-second rule was also featured in an [[MythBusters episodes: Season 3#Five-second Rule|episode]] of the Discovery Channel series ''[[MythBusters]]''. The results they got from their tests confirmed Clarke’s findings: time was not a factor when food is exposed to bacteria; even two seconds' exposure is more than enough time to contaminate it.

==Seating rule==

The rule is used at parties or other busy gatherings where seating is in short supply. If someone leaves their seat to visit the toilet or get a drink then the ''five second rule'' gives them five seconds' grace before their seat is claimed by someone else.

In some variations, a person vacating a seat may call "fives," giving them five minutes before the seat may be taken. If they have vacated the seat but forget to call fives, they are given five seconds to either invoke the rule or sit down again before the seat is considered able to be taken.

Another more permanent term is "Spotters" where a person will "call" the seat so that when they return it is not lost to another person. Other terms for this include calling "squats" or "shags".

As with the food rule, the actual length of time used will vary. The most common times given are three and five seconds.

It is often considered that the person claiming the unoccupied seat has more "right" to it the longer they wait before sitting down. A person may stand guard in front of the seat for ten or fifteen seconds before sitting down, both ensuring that no-one steps in before them and that their claim cannot be disputed.

==See also==

*[[Cooties]]

*[[Calling shotgun]]

==References==

* {{cite web | title=2004 Winners of the Ig Nobel Prize | work=The Ig Nobel Web Page | url=http://www.improb.com/ig/ig-pastwinners.html#ig2004 | accessdate=April 7 | accessyear=2005}}

==External links==

* [http://www.newhousenews.com/archive/sefton092903.html Article on experiment conducted by Jillian Clarke and Meredith Agle]

* [http://web.aces.uiuc.edu/news/stories/news2467.html Another article on Clarke experiment]

* [http://news.bbc.co.uk/1/hi/health/3505414.stm BBC article on bacteria levels in a typical office]

* [http://www.washingtonpost.com/wp-dyn/content/discussion/2006/03/31/DI2006033101212.html?nav=topnav Q&A with Dr. Charles P. Gerba]

* [http://www.urbandictionary.com/define.php?term=3+second+rule Urban Dictionary definitions of the 'three second rule' (both meanings)]

* [http://www.waff.com/global/story.asp?s=1483067&ClientType=Printable www.waff.com 's story on the 5 second rule experiment carried at the University of Illinois]

[[Category:American cultural conventions]]

[[Category:Food safety]]

[[Category:Misconceptions]]

[[Category:Rules of thumb]]

[[Category:Applied microbiology]]

[[Category:Urban legends]]

[[Category:Rules of thumbPseudoscience]]

[[Category:American cultural conventions]]

[[eo:Kvin-sekunda regulo]]

[[ja:5秒ルール]]

[[pl:Reguła pięciu sekund]]