Food on the Floor: 5-Second Rule May Have Some Truth to It

The "5-second rule" - that bit of urban folklore that supposes any food item accidentally dropped on the ground is still "safe" to eat so long as it hasn't remained there for 5 seconds - may have some scientific truth behind it, according to research from a microbiologist at Aston University in the UK.

Anthony Hilton, a professor of microbiology at Aston University, led the research, which was conducted as part of a biology class.

While the study has yet to be published in a peer-reviewed journal, its findings offer some fun food for thought.

"Our study showed that a surprisingly large majority of people are happy to consume dropped food, with women the most likely to do so," Hilton said in a statement. "But they are also more likely to follow the 5-second rule, which our research has shown to be much more than an old wives' tale."

To put the 5-second rule to the test, the researchers used two common types of bacteria Escherichia coli (E. coli) and Staphylococcus aureus and monitored how quickly it transferred from a variety of ground surfaces to food items.

Flooring including carpet, tile and laminate were included in the test, and the food items tested included toast, pasta, cookies and a "sticky sweet."

The study confirmed that time is, indeed, a significant factor in the transfer of bacteria from a floor surface to a food item. But the team also found that the type of flooring can also have an effect in how quickly bacteria can transfer to a food item. Carpet, for instance, was most resistant to quick bacterial transfer. Smooth surfaces such as tile or laminate, when in contact with a moist food, were the quickest to transfer bacteria after making contact for more than 5 seconds.

Hilton and his team concluded that food that has fallen on the floor is less likely to to contain bacteria if it's left there for a few seconds than if it's left there for longer.

"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," Hilton said.

In a survey associated with the study, 87 percent of people said they would eat food dropped on the floor. More than half of people who have eaten food off the floor were women, the survey revealed, and 81 percent of the women who have eaten or would eat food off of the floor employ the 5-second rule.