Five-second rule

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,[1] and the origin of the idea is unclear.

[2] Food scientist Pawl Dawson and microbiologist Brian Sheldon have traced the origins to legends surrounding Genghis Khan in the 15th century.

[7] 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.

"[10] 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.

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

[12] 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.

[14] 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.