Is there such thing as a five-second rule?

Food left on a surface can collect 150 to 8,000 bacteria. Image: Shutterstock

The food myth disproven.

Everyone knows the drill: Your tasty treat falls to the floor, you quickly pick it up, pretending nothing happened, and continue eating. However, the idea that it takes less than five seconds to contaminate food couldn’t be more incorrect, according to food scientist Paul Dawson of Clemson University, US.

“In the case of the five-second rule we found that bacteria was transferred from tabletops and floors to the food within five seconds,” says Dawson in a statement, published in the Journal of Applied Microbiology. “That is, the five-second rule is not an accurate guide when it comes to eating food that has fallen on the floor.”

In his research he determined that salmonella and other bacteria can survive up to four weeks on dry surfaces and transfer to food immediately upon contact. In other words, if your food touches the ground, it should not then touch your tongue.

In conducting the experiment, Dawson’s food of choice was bologna sandwiches dropped on tile, wood and nylon carpet contaminated by salmonella. Sandwiches left on the surfaces collected 150 to 8,000 bacteria. If they were left for a full 60 seconds, ten times more bacteria were found.

However, Dr Paul Pottinger, an infectious disease specialist at the University of Washington, US, believes it’s not seconds that count, but the location of where you drop the food. “Brushing off a bagel you dropped on the sidewalk and eating it is probably safe because the pavement is cleaner than a kitchen floor in terms of the kinds of bacteria found there,” he explained in a press release. Likewise, bathrooms should also be considered zero-second zones.

Dawson concluded from additional experiments that repeated dunking into a dip or sauce using the same edible vehicle — the so-called double-dipping — is another routine practice that can spread bacteria. Although illness may not result, “It’s like you’re kissing someone,” he says, “and it’s not just a peck on the cheek.”

Source: Journal of Microbiology

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