The Five Second Rule: Myth or Real?

“Oops!” you say as you drop your last biscuit onto the ground. Immediately, you start counting to 5. You snatch the biscuit at the last minute and quickly shove it into your mouth. But wait. Is it really safe to eat? And if so, should you eat it?

To answer this question, we have to check a variety of factors.

Factor 1: What kind of floor was it?

First, let’s start out by checking the floor you dropped this biscuit onto. Let’s say you dropped the biscuit onto your kitchen floor that is cleaned about every other week. Let’s say the type of floor in your kitchen is tile. Surprisingly, tile floors have a tendency to transfer bacteria more, and carpets transfer less. The reason that carpets transfer less bacteria is because the fibers of a carpet basically capture the bacteria so that they can’t invade your food as fast. Tile floors don’t do that, so they actually encourage bacterial development.

Factor 2: How long was it on the floor?

The next thing we need to check is the time on the floor. You picked up that biscuit approximately 4 seconds after it dropped to the ground. Interestingly enough, it doesn’t make too much of a difference if you picked it up 1 second after dropping or 4. But, that doesn’t mean it’s not important. The thing is, bacteria can transfer immediately on contact. The longer you wait just means that there is more bacteria on the food than before. This is what makes the difference between 1 second and 4 smaller than expected.

Factor 3: What kind of food was it?

Now we need to check for the type of food that was dropped onto the ground. We already know this. It was a biscuit. Biscuits actually are pretty high risk foods to drop onto the ground, meaning that they have a pretty high rate of bacteria contaminating them. Some other types of foods that would be considered ‘high risk’ would be moist or sticky foods. Now, you may be thinking biscuits aren’t moist or sticky, so how can they be high risk? Well, actually, by moist we are being very picky. Compared to dry crackers, biscuits are actually pretty moist. The drier and harder the food is, the slower the bacteria contaminates it.

Factor 4: What bacteria might be on your floor?

Finally, we need to talk about the germs that may be contaminating your floor. The most common types of bacteria that lie on your floors would be Escherichia coli (commonly abbreviated as E. coli), Salmonella, and finally Staphylococcus aureus (aka staph). All of these bacteria can cause anything from mild symptoms to death.

Given that the floors you have are cleaned around every other week, it’s not super clean, but it’s not that bad. But, if you wear your shoes indoors, or raw food prep happens nearby, or pets roam freely around the house, there’s a high chance the floor is dirtier than it looks.

So… should you eat it?

But all of this still doesn’t truly answer our question: should you eat it?

Technically, yes you can. Lots of people everywhere eat food off the ground, and all of them are ok. Scientifically, you have a risk, because the five second rule is not foolproof. But next time you drop your food on the ground and pop it in your mouth before thinking twice, don’t worry. The truth isn’t that the five second rule works. It’s that most of the time, we just get lucky. 🍪