By Mike Pomranz
Updated April 08, 2015
© iStockphoto

Yesterday was World Heath Day. To celebrate the occasion, the nation of Australia wanted to provide a friendly reminder that the “five-second rule” has nothing to do with protecting your health.

Not that the five-second rule doesn’t have some level of merit. But Australia’s Food Safety Information Council pointed out that when you drop food on the floor, bacteria isn’t sitting around with a timer waiting five seconds to pounce.

“There's no such thing as a ‘five-second rule,’” said Rachelle Williams of the Food Safety Information Council. “It's a myth; we definitely do not recommend it.”

But that doesn’t mean all dropped food becomes immediately contaminated—it’s just that there’s no specific timetable. What’s actually more important than how long food has been on the ground is what you’ve dropped. “It all comes down to bacteria,” Williams continued. “Bacteria rely on moisture to grow, so any wet food is considered potentially hazardous. It's much easier for bacteria to grow on those foods…With dry foods, it is conversely much tougher for bacteria to grow.”

If that sounds like a mixed message, it’s not. What is important is recognizing that there’s more to determining whether your food has been contaminated than a simple rule about time. For instance, as RMIT University points out, bacteria is technically all around us, even on our food, at all times. And though more time on the floor will mean more bacteria, other factors come into play—things like the amount of pressure applied to the food after it falls and how dirty the surface was to begin with.

So, figuring out whether your food is still safe to eat after it’s hit the floor is actually a somewhat complex set of calculations derived from a number of variables including the type of food, how long it’s been on the floor, how much pressure was applied and how dirty the floor is.

A better way to think of the five-second rule is probably this: If all those calculations take your brain more than five seconds to process, you probably want to let that slice of pizza go.

[h/t Munchies]