The Brutal Truth About the Five-Second Rule

Science weighs in on polite society's greatest debate

September 9, 2016 9:00 am

Your mom warned you and you brushed her off, but deep down you knew this day was coming.

We hate to be the bearers of bad news, champ, but the five-second rule, well, it’s all been a lie.

During a study that probably wasn’t entirely necessary, Rutgers researchers proved that it is not safe to eat food that’s fallen on the floor, even if you do it within a five-second window. Turns out that in some cases — like, say, if you dropped a taco on the floor of a rest stop bathroom — the transfer of bacteria begins in less than a second.

The rate of cross-contamination depends on a variety of factors (surface type, food variety, contact time, bacteria level) but the 2,560 measurements the researchers performed clearly showed that the five-second rule is a bunch of bupkus. If you must insist on eating food off the floor, go with a cracker that landed on carpet before a piece of watermelon that on tile, according to food science professor Donald Schaffner.

“Transfer of bacteria from surfaces to food appears to be affected most by moisture,” Schaffner says. “Bacteria don’t have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer … Bacteria can contaminate instantaneously.”

One other finding the study proved? Rutgers researchers have too much time on their hands.

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