The rule beloved by many, popularized by kindergarteners and used by adults. The 5 second rule is one of or maybe the most well-known urban legend related to food hygiene ever. With a survey conducted in 2003 by high school student Jillian Clarke showing that 56% of men and 70% of women surveyed knows or at least were familiar with the rule. The 5 second rule has no clear origins but food scientist Pawl Dawson and microbiologist Brian Sheldon have traced the urban legend to Genghis Khan, the founder and first khan of the Mongol Empire.

Now it's time to get into the fun stuff, science. A study published by Robyn Miranda and Donald Schaffner in 2016 at Rutgers University shows research and testing on 4 different types of food. The food that were unlucky enough to be dropped 4 times on different materials were bread, bread with butter, gummy candy, and watermelon. Each item were tested on tile, stainless steel, wood, and carpet to account for different types of situation.

The study shows that longer contact with the floor did result in transfer of more bacteria though there were also times where the transfer was instantaneous but this highly depends on the food and floor material. Due to its high moisture, watermelon had the highest rate contamination while gummy candy surprisingly had the lowest. And for what's the best surface to drop your food on, surprisingly for me at least is carpet. Carpet has a lot crevices so the bacteria would fall and sit underneath the surface while the food sat on top.

So in conclusion as Robyn Miranda said it herself. “It’s science, Everything depends.”

https://en.wikipedia.org/wiki/Five-second_rule

https://en.wikipedia.org/wiki/Genghis_Khan

https://journals.asm.org/doi/10.1128/aem.01838-16

https://www.sciencefriday.com/articles/the-origin-of-the-five-second-rule/