Researchers Drop Food on the Floor to Test Five Second Rule

Posted on March 10, 2014

Researchers from Aston University dropped food on different surfaces for brief amounts of time to test the five second rule, an urban myth that food is safe to eat if it has only been on the ground for only seconds. The researchers dropped toast, pasta, a biscuit and a "sticky sweet" on the ground and left it there for 3 to 30 seconds. They then tested the food for levels of Escherichia coli (E. coli) and Staphylococcus aureus. Three different surfaces were tested: carpet, laminate and tile.

The study found that time is a significant factor in the amount of bacteria transfered from the surface of the floor to the food. Bacteria was the least likely to be transfered from a carpeted surface and most likely to be transfered from laminate or tiled surfaces. As you might expect moist foods were the most likely to retain bacteria from the floor.

Anthony Hilton, Professor of Microbiology at Aston University, said in a statement, "Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor at the time; however the findings of this study will bring some light relief to those who have been employing the five-second rule for years, despite a general consensus that it is purely a myth. We have found evidence that transfer from indoor flooring surfaces is incredibly poor with carpet actually posing the lowest risk of bacterial transfer onto dropped food."

The researchers also surveyed people who use the five-second rule. The survey revealed the following findings:

An extremely high magnification of a colorized scanning electron micrograph of an Escherichia coli bacterium from the CDC is pictured above.

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