Five-second rule

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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.

The five-second rule, sometimes known as the three-second rule,[1] is a food hygiene myth that states a defined time window where it is safe to pick up food (or sometimes cutlery) after it has been dropped and thus exposed to contamination.

There appears to be no scientific consensus on the general applicability of the rule,[2] and its origin is unclear.[3][4][5] It probably originated succeeding germ theory in the late 19th century. The first known mention of the rule in print is in the 1995 novel Wanted: Rowing Coach.[6]


The five-second rule has received some scholarly attention.[7] It has been studied as both a public health recommendation and a sociological effect.

University of Illinois[edit]

In 2003, Jillian Clarke of the University of Illinois at Urbana–Champaign found in a survey that 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 E. coli.[8] On the other hand, Clarke found no significant evidence of contamination on public flooring.[8] For this work, Clarke received the 2004 Ig Nobel Prize in public health.[9] A more thorough study in 2006 using salmonella on wood, tiles, and nylon carpet, found that the bacteria were able to thrive under dry conditions even after twenty-eight days.[10] Tested on surfaces that had been contaminated with salmonella eight hours previously, the bacteria were still able to contaminate bread and bologna in under five seconds. But a minute-long contact increased contamination about tenfold (especially tile and carpet surfaces).[11]

Rutgers University[edit]

The researchers at the Rutgers University debunked the theory in 2016 by dropping watermelon cubes, gummy candies, plain white bread, and buttered bread from a height of five inches (13 cm) on to surfaces slathered in Enterobacter aerogenes. The surfaces used were carpet, ceramic tile, stainless steel and wood. The food was left on the surface in 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, said in a statement in the Washington Post. "Bacteria can contaminate instantaneously."[12]

A pediatrician criticized the study for discounting the danger in consuming certain foods dropped onto floors.[13]


A 2006 study at Clemson University was unable to verify the rule, when looking at tile, wood, and carpet floors. It indicated that bacteria can survive on the ground for a long time.[14]

A 2014 study by biology students at Aston University in England suggested that there may be a basis for the five-second rule.[15] 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.[16]


The five-second rule was featured in an 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.[17]

Ted Allen put the rule to the test in an episode of Food Detectives,[18] and found that bacteria will cling to food immediately.

The YouTube channel Vsauce also dedicated a video to this topic, concluding that it would be more correct to call it the "Don't Touch Food That's Fallen on the Floor Rule".[19]


  1. ^ (7 February 2006) Getting the dirt of the 5-second rule, Southeast Missourian
  2. ^ Leanna Skanulis (2007). "'5-Second Rule', Sometimes". WebMD. Retrieved March 15, 2017.
  3. ^ Sefton, Dru (2003). Intern Puts Science Behind the Five-Second Rule, Newhouse News service
  4. ^ Kluck, Chad (2000). I Think Therefore I Am: A Collection of My Thoughts. p. 35. ISBN 9780533133246.
  5. ^ (16 May 2007). Kissing Away the Germs (letter to editor), The New York Times
  6. ^ Mayer, Johanna. The Origin Of ‘The Five-Second Rule Science Friday, 20 February 2019.
  7. ^ Julie Deardorff "Capsule: The five-second rule" Los Angeles Times, August 9, 2010, accessed January 18, 2011.
  8. ^ a b Picklesimer, Phyllis (2003-09-02). "If You Drop It, Should You Eat It? Scientists Weigh In on the 5-Second Rule". ACES News. University of Illinois College of Agricultural, Consumer, and Environmental Sciences. Retrieved 2013-05-04.
  9. ^ "Improbable Research". Archived from the original on 2009-08-30. Retrieved 2008-04-24.
  10. ^ Dawson, P.; I. Han; M. Cox; C. Black; L. Simmons (April 2006). "Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule". Journal of Applied Microbiology. 102 (4): 945–953. doi:10.1111/j.1365-2672.2006.03171.x. PMID 17381737.
  11. ^ McGee, Harold (2007-05-09). "The Five-second Rule Explored, or: How Dirty Is That Bologna?". The New York Times. Retrieved 2007-05-09.
  12. ^ "The 'five-second rule' for eating food? Scientists just demonstrated how gross it is". Washington Post. Retrieved 2017-02-10.
  13. ^ Aaron Carroll, "I'm a doctor. If I drop food on the kitchen floor, I still eat it." New York Times, 10 Oct 2016.
  14. ^ Anupriya, P.; Han, I.; Cox, M.; Black, C.; Simmons, L. (2007). "Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule". Journal of Applied Microbiology. 102 (4): 945–953. doi:10.1111/j.1365-2672.2006.03171.x. ISSN 1364-5072. PMID 17381737.
  15. ^ "Researchers prove the five-second rule is real". Aston University.
  16. ^ Ryan Hooper (March 15, 2017). "'Five-second rule' for food dropped on the floor approved by germ scientists". The Independent (UK). Retrieved March 15, 2017.
  17. ^ "Annotated Mythbusters: Episode 39 Chinese Invasion Alarm, 5 Second Rule". Retrieved 2008-08-17.
  18. ^ "Food Detectives, Episode OF0101". Archived from the original on 2011-05-06. Retrieved 2011-01-31.
  19. ^ Archived at Ghostarchive and the Wayback Machine: Vsauce (30 November 2012). "Is The 5-Second Rule True?" – via YouTube.