The Five-Second Rule

Do you follow the “Five-Second Rule”? It sure is handy with a toddler in the house… but just how quickly can bacteria get from the floor to your food?

{This post was sponsored by Indiana’s Family of Farmers. All thoughts and opinions are my own. Referral links were used in this post.}

I’ve done it, my husband has done it, and my son has certainly done it. You drop something yummy on the floor, bend over to pick it up, and pop it in your mouth – justifying this with the “five-second rule.” Is the five-second rule a real thing? If you pick up that M&M before 5 seconds is it okay, but waiting until the magical 6th second means you need to throw it out?

What about a cookie? Or a green bean?

Would you still pick it up and eat it, if it was a green bean instead of an M&M?

Does the time really matter?

Well, it depends.

How Long Do Bacteria Live?

Part of the “it depends” answer is because different bacteria can live for different lengths of time on your floor. In general, bacteria prefer warm, damp places to live. (That’s part of the reason that bacterial growth slows down in your refrigerator – it’s too chilly for them.) But plenty of bacteria can survive on dry surfaces, like your kitchen floor.

Paul Dawson, a researcher at Clemson University, looked at how long Salmonella typhimurium could survive on kitchen tiles. He put a certain number of Salmonella bacteria on each tile, and looked at the numbers of bacteria that were there up to 28 days later. While the numbers of bacteria decreased over time, there were still plenty left after 28 days. So this strain of Salmonella can live up to 28 days on a dry floor (remember, this is one of the bacteria that can cause food poisoning). Which means that plenty of other bacteria can also live up to 28 days on a floor.

No matter what kind of bacteria we’re talking about, they can all live for at least 5 seconds.

What Kind of Food is It?

In Dawson’s paper, they also compared how many bacteria transferred from the floor to a piece of bologna (wet) or a piece of bread (dry) after 5 seconds, 30 seconds, or 60 seconds. Both the bologna and the bread picked up lots of bacteria, no matter how long they sat on the floor. Overall, Dawson recommends a “zero-second rule.”

MythBusters Agree

If the MythBusters agree, you know it must be true! The MythBusters declared the 5-second rule BUSTED after their tests. They found that wet foods (a piece of pastrami) picked up more bacteria than dry foods (a cracker). But both the pastrami and the cracker picked up bacteria after only 2 seconds – and there was no difference in the amount of bacteria they collected after 6 seconds.

A Different Point of View

Anthony Hilton, at Aston University, has a slightly different perspective. His study found that time does make a difference – the longer the food is there, the more bacteria it picks up. (I have not been able to find this study published, just the press release from Aston University and a handful of media articles about it.)

Five Seconds? Your Call

It’s your health (or your family’s health), so it’s your decision. Some scientists think that a general low-level stimulation of your immune system (perhaps by eating food off the floor occasionally) can help your immune system grow strong and work better. On the other hand, it only takes a very small number of some bacteria to make you sick, no matter how strong your immune system is.

Things to Consider When Following the Five-Second Rule

When is the last time you washed your floor? As a busy mom on a busy farm, I will honestly say that it’s been way too long since I washed mine. Washing your floors will remove bacteria, but not all of them. Remember, bacteria can live up to (and probably longer than) 28 days… but the longer you go between washings the more bacteria can accumulate there.
What kind of floor is it? According to Dawson’s and Hilton’s studies, carpet transfers less bacteria to food than tile or wood. So maybe that means there’s less of a risk with carpet.
Where is the floor? Is it the kitchen? Right in front of the sink or in the main traffic pattern? Is it the corner of the room where no one walks? Is it the bathroom? Use your judgement… Just keep in mind that any time you use your kitchen sink microdroplets of water splash all over, carrying bacteria with them. And the same thing happens every time you flush the toilet.
What did you drop? Dry crackers are probably not a very big deal. The jelly side of a piece of toast probably is. While wet and dry foods will both pick up bacteria from the floor, wet foods will pick up more bacteria faster.
Can you wash the food? A potato that you are still going to scrub, peel, and cook is okay to eat after you dropped it. If you drop an apple slice or a bunch of grapes, you should wash them again before you eat them.
Are you at risk for food poisoning? If you (or the person doing the eating) is at risk for food poisoning or any other kind of illness, you should probably avoid eating food off the floor. At risk groups include young children, elderly adults, pregnant women, or anyone with a compromised immune system.

For me? I’m going to make a serious effort to keep my floors cleaner (this helps). And I’ll stop snacking off the floor. (Not that it was my favorite place to eat, anyway.) But – in all reality – there is no keeping my toddler from grabbing that dropped Cheerio or the coveted fruit snack off the floor. (Moms, back me up here!) So I’ll do my best to keep it clean for him, and hope that this is just immune system training.

Want to have a little fun with the Five-Second Rule? Check out this family game! There is no relation to food safety, other than the name of the game. But it sure looks like a lot of fun!

The Five-Second Rule