The ‘5 second rule’ is an unwritten rule among some groups which dictates that if a piece of food is dropped onto the floor, you can pick it up and eat it within five seconds without the food becoming contaminated with dirt or germs.
If you use the 5 second rule then you’ll probably be interested to learn that the jury is out on whether time is a significant factor in the transfer of some bacteria; two conflicting studies give us a different viewpoint.
A study at Aston University, Birmingham found that the transfer of common bacteria such as Escherichia coli (E. coli) and Staphylococcus aureus can take between 3 and 30 seconds. It also found that those bacteria are least likely to transfer to dry food from a carpeted surface; unfortunately the same can’t be said for carpet fibres!
If the dirt, hairs and dust from your floor aren’t enough to put you off then this might.
A study in the Journal of Applied Microbiology tested the survival of Salmonella on wood, tile and carpeted surfaces and also the transfer from these surfaces to meat and bread. The study concluded that Salmonella bacteria can survive on a dry surface for up to 4 weeks and also transfer to any foods dropped onto the surface almost instantly.
All things being considered, I certainly can’t recommend eating any ready-to-eat food that you’ve dropped on the floor. Without testing from a qualified microbiologist it’s difficult to know what kind of bacteria might be present on the surface; furthermore eating any food dropped onto any surface carries a risk of infection, especially so if you are a pet-owner or are particularly vulnerable to infections.
This article originally appeared on The Hygiene Doctor.