Fallen Food: About the 5 Second Rule | PostIndependent.com

Fallen Food: About the 5 Second Rule

Phil Mohler, M.D.
Free Press Health Columnist

It is not a rare event at our house to evoke the 5-, 10- or even 30-second rule when food hits the floor. Allegedly, Genghis Khan abided by a 12-hour rule. So is it OK to eat food that has fallen on the floor?

In an unpublished study from 2003, a high school student found that gummy bears and fudge-striped cookies dropped on ceramic floor tiles that had been inoculated with the germ E. coli picked up the bacteria in less than 5 seconds. That is … germs can hitch a ride on food upon contact. The student also found that women are more likely than men to pick food up off the floor and eat it and that sweets are more commonly rescued than veggies.

In a study from Clemson University published in a bacteriology journal in 2007, the researchers covered floors made of tile, wood and nylon carpet with a soup of Salmonella bacteria. Then they dropped baloney sandwiches on the floors and analyzed the results. Within 5 seconds the baloney and bread picked up 150 to 8,000 bacteria, the least from the carpet, most from the tile. A minute-long contact increased contamination tenfold (on the tile and wood only).

In an episode of “The MythBusters” on the Discovery Channel, the experimenters found no significant difference in the number of bacteria collected after food was on the floor for two seconds versus six seconds.

The other part of the equation is whether or not consumption of significant numbers of bacteria is harmful. Microbiologists predict dire events. My personal experience suggests very benign outcomes from consuming food dropped on the floor.


The scientist in me, having reviewed the evidence, believes that it should be the “zero-second rule.” The lover of all pastries in me confesses that when my donut hits the floor, it will be retrieved and likely eaten.

Dr. Mohler has practiced family medicine in Grand Junction for 38 years. He has a particular interest in pharmaceutical education. Phil works part-time for both Primary Care Partners and Rocky Mountain Health Plans. Email him at pjmohler@bresnan.net.

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