The five second rule debunked


What REALLY happens when your food falls on the floor


Sometimes, mornings are a nightmare.

Today my daughter decided she was fed up with school, fed up with uniforms, fed up with breakfast… fed up with LIFE.

“It’s just…. not…. Fair…”

She sat slumped across the table, head buried in her arm, as if she’d received the most tragic news imaginable.

On days like these, it’s like she’s an “emo” teenager trapped in an eight-year old’s body.

I knew this sort of thing was coming…. but not so quickly!

I stared at the clock. The big hand seemed to be whizzing around at triple speed. We were going to be late and end up running red-faced into the school…again.

She was ignoring the muesli and the fruit I’d put out for her, so I switched to ‘emergency toast’. Anything to get some food in her so that we could leave.

The toast, coated in peanut butter, made her smile, despite herself. (Don’t worry, health conscious reader, it’s the stuff without sugar and salt),
She picked it up by the corner, trying to pretend she didn’t care about it, and swung it towards her mouth… then it slipped from her fingers.

As the toast hit the floor my wife cried out “FIVE SECOND RULE” and picked it up.

At this point, I found myself in a quandary…

Here I was, late for the school run and potentially late for work as your devoted health science researcher…

My wife had scooped up the toast and slammed it back on my daughter’s plate. I really needed my daughter to eat that toast without any further distractions and no new reasons to fly off the handle.


Because I’m a geek who reads a zillion science and health articles every year, I had recently discovered something about the ‘Five Second Rule’.

…the rule is probably NOT true!


• Do I consign my daughter to bacterial oblivion for the sake of getting her to school on time?

• Do I resist my urge to correct people, even my wife, when they get the science wrong?

• Or do blurt out the truth and accept that I’ll have to make the toast again?

I’ll give you the answer in a moment.

But first, here’s what I’ve found out about the 5 second rule….

The Five Second Rule Debunked!

On the 9th of September this year, new research challenged the belief that there’s a safe period of 5 seconds when something falls onto a contaminated surface.

This could be a hot dog sliding out of the bun and hitting the floor… or a baby’s dummy being hurled out of the pram and falling onto a dirty street.

According to an article by Professor Donald Schaffner in the American Society for Microbiology’s journal, Applied and Environmental Microbiology, the contamination can occur in just a second.

He and a team tested a ranged of surfaces (steel, tiles, carpet, wood) and four foods: watermelon, bread with butter on it, bread without butter, and soft fruit sweet.

They found that moisture is the key to how quickly bacteria transfers. It means that something like watermelon would see the quickest transfer of bacteria, while the fruit sweet would have the least.

They also found that carpet had the lowest transfer speed, while tile and stainless steel had the highest.

Whatever the case, while it’s true that the longer something stays on the floor the more contaminated it gets… there is no standard five second window. A gummy bear sweet landing on carpet might work with the 5 second rule, but a slice of apple falling on a dirty tile floor might not.

This backs up some research in 2014 by Jorge Parada, from the Infection Prevention and Control Program at Loyola University.

He says: “A dropped item is immediately contaminated and can’t really be sanitized. When it comes to folklore, the ‘five-second rule’ should be replaced with ‘When in doubt, throw it out.'”

He also explains what he thinks the five second rule is really about…

According to Parada, the rule is a “polite fiction” that allows us to get through life more easily. By telling ourselves it’s fine to pick up that dropped burger, or fallen baby’s dummy, we can avoid….

• Having to pay for ANOTHER burger.

• Cancelling the lovely walk in the park and going home to get a new dummy.

• Being late for school because the toast has fallen on the floor.

So what did I do?

Well, I went with the fiction and let her eat the toast.

But before you judge me as a bad Dad…

Here’s my defence…

The Common Sense Approach to Health

While I know that germs can transfer almost instantly when food is dropped…
I also don’t want my kids to life in constant obsessional fear about bacteria, about contamination, about perils to their health that stop them from living life.

I’m absolutely sure that at school and when they’re out playing they get their hands into all kinds of muck and mess. They probably don’t always wash their hands properly before they eat and they live in an intensely rich bacterial stew of germs when they’re in the classroom, dinner hall and playground – no matter how clean the school is.

Better she can be spontaneous and wild in these previous young years than to be terrified of invisible microscopic monsters on every surface.

It’s also true that exposure to germs in can be beneficial.

In 2012 a study in Science showed evidence that being exposed to germs as a child can reduce the amount of T (iNKT) cells in your body. These are natural defenders against infection but they can also “switch on” auto-immune reactions like asthma or ulcerative colitis (inflammatory bowel disease.)

In other words, you need a certain amount of exposure to bacteria in your childhood to help train your immune system, or as the research leader put it “set the thermostat”.

Then there was a Canadian study published in 2015 which found that children who were lacking in certain bacteria (Faecalibacterium, Lachnospira, Veillonella, and Rothia) were more likely to develop asthma.

So what do you think?

Are we too clean these days? Too worried about bacteria? Too quick to bring out the anti-biotics and anti-bacteria sprays?

Or am I going to have to relinquish my “Number 1 Dad in the World” slot next Father’s Day? (An award, which I am proud to say, I’ve won 7 years in a row!)

Answers on a postcard please. Or, actually, an email will do!

Until the weekend, stay healthy!


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