Rutgers University researchers just busted a long-standing myth: it’s not necessarily safe to eat food off the floor if you pick it up right away.
The theory behind the five-second rule is that it takes time for bacteria to transfer from surface to surface, so if you grab your chip soon as it hits the ground, it’s fair game.
The scientists put that theory to the test. They dropped various foods onto germ-covered surfaces and determined how much bacteria the foods picked up after less than a second, five seconds, 30 seconds and five minutes.
The result: some bacteria transferred instantly. That means it’s never 100 per cent safe to eat food off the ground, says study coauthor Donald Schaffner.
Some foods are riskier than others, though.
For example, when a piece of watermelon hit the deck, it instantly picked up 97 per cent of the bacteria that had been on the ground. In that case, you’d be no better off eating the fruit after a split second on the floor than you would be after letting it fester for five minutes.
Bread, however, did accumulate more bacteria over time. In a fraction of a second, 0.1 percent of the germs had transferred, but after five seconds, 10 per cent of the bacteria had made its way to the bread.
That’s probably because of the differing moisture levels, Schaffner says. Moisture helps bacteria transfer, so the wetter the food, the faster it picks up germs.
Still, even the bread snatched some germs in a split second. And if those bacteria were salmonella, you could get crook from eating the bread.
So if you want to play it safe, leave your chip on the floor, Schaffner says.
But if you’re the type of guy who likes to take his chances, now you can be better informed. Think about all the factors at play, says Schaffner, who admits to sometimes eating food off the floor himself.
“It depends on the nature of the food, the nature of the surface, the cleanliness of the surface and the health of the immune system of the person doing the eating,” he says.