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The 5- second rule

5-second rule

We have all experienced the situation when food falls to the ground. Are we tempted to pick it up as quickly as possible, or should it be thrown out?

When it comes to picking up food that has fallen on the floor, we often use the 5-second rule: if it was on the ground for less than 5 seconds, bacteria do not have sufficient time to transfer to the food. Scientists, however, appear to disagree with this mythical rule.

The idea that any kind of bacteria would wait five seconds before transferring to our food might seem quite comical to us. As bacteria transfer through moisture, the surface, along with the type of food that falls to the ground, affects the absorption of bacteria.

However, out of the people surveyed, 81% indicated that they would follow the 5-second rule and pick up the food from the ground. In light of this percentage, it is quite crucial to examine this subject in more detail.

Researchers from the State University of New Jersey have conducted an extensive study to support or debunk one of these myths. They have used four different surfaces, including stainless steel, carpet, tile, and wood, and dropped four different types of food on them. Additionally, the food varied in consistency and moisture since they included watermelon, bread, and bread with butter, as well as gummy bears. Two types of bacteria were present on the area, and food was dropped on it for 1, 5, 30 and 300 seconds.

The study consisted of 128 different scenarios, each of which was repeated 20 times in order to obtain a valid result. The results of the comparison of 2560 measurements were as follows:

  • Our food can be contaminated instantly by bacteria

  • It is more likely that bacteria will enter the food the longer we leave it on the ground

  • Due to its moisture, watermelon was the most contaminated fruit

  • Gummy bears, however, were the least contaminated

  • In contrast to steel, tile, and wood, carped had a lower transfer rate of contamination than these materials

Next time we drop some food to the ground, we might want to consider throwing it away instead.


Miranda, R. C., & Schaffner, D. W. (2016). Longer contact times increase cross-contamination of Enterobacter aerogenes from surfaces to food. Applied and environmental microbiology, 82(21), 6490-6496.

Researchers prove the five second rule is real. (n.d.). Retrieved September 05, 2017, from

Ellis, M. (2016, September 12). "The '5-second rule' is disproved in new study." Medical News Today. Retrieved from

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