Picture this: It’s breakfast time.
You’ve just made everyone else something to eat and just as you swipe some butter on your own piece of toast, it drops on the floor.
Right under the watchful eye of your toddler in their high chair, who loves anything that’s a bit of game and picks up her own toast and hurls it onto the floor.
"Damn it!", you think as you bend over to swipe it up.
With one eye on the clock and the other on your grumbling tummy, you snatch it off the floor and stuff it down.
Five second rule and all of that, right?
Right. Well, maybe. But should you really eat food you've picked up from the floor? Or is that just one of those lines we've all picked up and used, without ever really knowing whether it is true?
Well, you might want to consider the science, says Sarah Hunstead. The paediatric emergency nurse and author, and host of Babyology’s Ain’t That The Truth podcast knows the facts are out there.
Listen to Sarah on Ain't That The Truth:
Enter Professor Paul Dawson from Clemson University in the United States.
He discovered that American chef, Julia Child actually came up with the rule; famously uttering it after dropping a potato pancake onto the stove top during filming one of her TV shows.
“If no one’s watching, it’s fine to eat it,” Julia was said to have quipped, before flipping the pancake back into the pan.
The important questions
This discovery sent Professor Dawson on a bit of search - he started by testing a range of foods, from watermelon to sausages and bread, on various different surfaces like tiles, wooden floors and carpet.
The result? It seems it’s not about how long you leave the food on the floor, but more about what's already on the floor and how wet your food is.
As Sarah explains: "Watermelon moisture is really attractive to bugs of different kinds, like salmonella and E. coli, that give us gastro bugs. So watery foods are likely to pick up lots of bugs. While harder foods like dry toast or jelly beans are less likely to attract germs."
So the key questions are:
- What type and how moist is the food?
- How dirty is the floor?
These two factors are actually more important than how long you leave the food on the floor.
"If you drop something for a second or a minute, you’re unlikely to get sick," says Sarah. "But if you’re chowing down on a piece of toast, then you’re more likely to pick up germs from the moist buttery side, rather than the dry one."
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