The Truth About the 5-Second Rule

Last Sunday morning I was in a really good mood. For those of us in Australia, it was the first day of summer.áThe warmth of the sun was creeping through the window, smothering the kitchen in morning sunlight.

But that’s not why I was in a good mood. To be honest, I was just excited to sink my teeth into a vegemite and melted cheese sandwich — my delicious weekend breakfast.

As I was slicing a block of cheese, a small, deliciously bite-sized piece fell to the floor. Despairingly (thanks to what many would calláan ‘obsession’ over not wasting food) I quickly grabbed the no-longer-worthy-of-my-sandwich cheese off the floor. I was just about to put it in my mouth, calling the “five-second rule” as my defense, when I stopped mid-bite.áIs this cheese actually still clean and safe to eat, I wondered. Surely bacteria has already infested, considering hair and dust manage to stick to cheese in an instant.áIt got me thinking, just how many people would eat this bit of cheese. Would you have eaten it?

The Infamous Five-Second Rule

The five-second rule, the alleged time in which it takes bacteria to attach to your dropped cookie, is no strange phenomenon, having appeared on popular TV shows such as Greys Anatomy, The Simpsons and How I Met Your Mother. It’s a world-wide term that seems to get manipulated and abused often; I’m sure I’ve even heard someone claimá’the 5-minute rule’ once or twice before.

But is there any validity to the so-called five-second rule?

Perhaps it’s effective in social situations where you want it to seem somewhat acceptable to your peers that you’re eating food off the ground. However, from a scientific standpoint, no, the five-second rule is false. (And yes, some researchers actually managed to get funding to conduct research on this).

The Research

The first study was conducted in 2003áby a professor and her intern, Jillian Clarke, at the University of Illinois. Clarke placed food on E. coli-laden tiles foráfive seconds or less to test contamination levels. The foods used for the experiment were gummi-bears and fudge-striped cookies; customers reportedly value these foods more highly, thus making them more likely to be retrieved off the floor. Seriously.

In all cases, E. coli was transferred to the food in five seconds or less. (Clarke also found in surveys that women were more likely than men to eat food that’s been on the floor.)

In 2006 a more systematic study investigating how salmonella behaves on wood, tiles and nylon carpet found that after eight hours of exposure, the bacteria could still contaminate many foods in under five seconds. One minute or more of contact increased contamination tenfold on tile and carpet surfaces. Lead researcher Professor Paul Dawson concluded, “Salmonella Typhimurium can survive for up to 4 weeks on dry surfaces in high-enough populations to be transferred to foods and Salmonella Typhimurium can be transferred to the foods tested almost immediately on contact.”

Other Nasty Stuff on Your Floor (Think Fecal)

Robert Romaine, a San Diego County health inspector for 25 years and food safety consult, told WebMD, “We teach students that any surface, especially floors, should not be considered clean, and any food that comes in contact with it is trash.”

That includes counters that have been washed and sanitized. “Consider the potential for damp floors and what might be on the shoes of a worker who walked her dog or used the restroom before coming to work. Then someone lifts a carton of produce from the floor and sets it on the counter.”

The one thing that really caught my attention there is the word ‘restroom.’ Now the floor around public toiletsáis NOT clean — I don’t care how much bleach was used. You certainly don’t want bacteria from public restrooms anywhere near your face, let alone in your mouth.

Thanks to a study by Charles Gerba, we can be assured our shoes are hugging more than just our feet. The study out of the University of Arizona looked at 26 pairs of shoes and found that after three months of use, 93 percent of shoes have fecal contamination. The samples averaged 421,000 bacterial units per square centimetre — enough bacteria to reproduce and grow a new colony. Of those 26 pairs of shoes, seven had also managed to pick up E.coli.

This basically means that if you wear shoes inside, there’s poo on your kitchen floor. Even if you always leave your shoes at the front door, ask yourself where you put your handbag when using a public restroom.

What’s more, Gerba found that seven out of ten coffee tables of single men had fecal contamination. One would think (and hope) it’s from fellas resting their feet up on the table.

The Take-Home Message

According to the CDC’s National Center for Infectious Diseases, it’s estimated that in America 300,000 people are hospitalized and 5,000 die from a foodborne illness annually. Most deaths however, occur among susceptible populations that include small children, the elderly and people with weakened immune systems.

One thing you can be sure of is that from the moment your food makes contact with the floor, there’s some bacteria transfer occurring immediately. The extent of which depends greatly on the moisture level of food that was dropped, the size of the food, what type of surface the food came in contact with and of course what bacteria was already on the surface.

Whether you believe it’s salmonella, E. coli or the dreadedá’fecal content’áis your call.

Photo Credit: Thinkstock


Jim Ven
Jim Ven11 months ago

thanks for the article.

Panchali Yapa
Panchali Yapa2 years ago

Thank you

Kathy Perez
Kathy Johnson3 years ago

I would never eat food off the floor out in public.. but.. I am guilty of eating dry crackers off the floor at home.

Teresa Wlosowicz
Teresa W3 years ago

Hugh, maybe it's for astronauts while they are in outer space?

Rekha S3 years ago

Thanks for sharing.

Vicky P.
Vicky P3 years ago

knew about that :)

Amanda M.
Amanda M3 years ago

The MythBusters tested the "five-second rule" on one of the show episodes, and they did confirm that germs can get onto the food regardless of how fast you pick it up. A lot also depends on what KIND of food is dropped as well-dry food vs. moist, smooth-surface vs. porous, etc.

Our household is of two minds on that subject. At home, it depends on what kind of food hits the floor. If it's something that can be easily cleaned off, no sweat-we'll just pick it up, clean it off, and eat it. If we're in a public place or outdoors, however, the "five-second rule" pretty much is null and void. Once something hits the floor/ground, forget it-it's garbage.

We catch our fair share of colds and noroviruses, but that's due mostly to having school-age kids and my husband working in a low-wage job where there's no paid sick leave whatsoever, which pretty much requires him and his coworkers to drag themselves in even if they're barfing up a lung or something. You don't work, you don't get paid, and the paychecks suck enough.

Jeff Prystupa
Jeff Prystupa3 years ago

If you get vaccines - do not worry about anything like eating food that hits the floor - you are getting such a dose of toxicity and 'microbia' that it makes questions like this stupid. If you eat it - your digestive enzymes will tear it apart - if you inject it into the blood (vaccine) then you have something to really worry about. If you are getting vaccines, you might as well eat off the floor - all the time.

JoAnn Paris
JoAnn Paris3 years ago

I have never heard of this rule but I will keep my own - if it hits the floor it's history.

Ei A.
Ei R3 years ago

Never believed it and always figured to be safe I would throw it away.