I’m sure we have all heard the five second rule at some point in our lives, and it states that if you drop food on the ground, you’ll have five seconds to pick it up and still be able to eat it. Obviously if you drop something outside or on a very dirty floor, you should not eat it because the food will definitely be dirty, however I was curious to see if there was some truth to this myth. If food was dropped on a normal floor, I wondered if it would actually take five seconds for germs to accumulate on it.
A study was done by Jillian Clarke to determine if this myth is true. She covered floor tiles with E.coli and then dropped gummy bears and cookies onto the contaminated floor. She removed the food from the floor after five seconds and observed that a lot of bacteria had gotten onto the food despite the fact that it was only on the floor for five seconds. This experiment shows that the five second rule is not true because bacteria still managed to get on the food within five seconds.
A concern about this experiment may be that floors will not be as dirty as the one Clarke used, and that for the most part floors are kept relatively clean, especially in houses which is where the five second rule is most commonly used. A study done by the Hygiene Council showed that common kitchen floors have a lot of bacteria on them. They have 830 per square inch, which is double that of inside a trashcan. This shows that floors are usually dirty and that bacteria would contaminate the food.
These two studies provide pretty solid evidence that the five second rule is not true. Bacteria clearly got onto foo within five seconds, and floors contain enough bacteria for this to happen. Based on this I would not trust the five second rule and I recommend that nobody else does too despite who says its okay or how good the food looks.
source 1: http://science.howstuffworks.com/science-vs-myth/everyday-myths/five-second-rule2.htm
source 2: http://science.howstuffworks.com/science-vs-myth/everyday-myths/five-second-rule.htm