The Five Second Rule, or do you eat dropped food?

Is the Five Second Rule a myth, or do you eat dropped food?

by rich on April 3, 2011

You know those times when you’ve just promised a biscuit to a four-year old, and then you accidentally scatter them all over the kitchen floor, leaving the four-year old with a look of pure horror and dismay on her face?

What do you do?

Normally, I’d just scoop the pile of broken biscuits up and dump them straight in the bin, but this time The Five Second Rule was invoked.

What on earth is the Five Second Rule, I asked?

The Five Second Rule, I was told (quite confidently, I thought), states that if a piece of dropped food rests on the floor for less than five seconds, it’s still OK to eat.

This is scientific FACT, apparently.

Some discussion followed about this supposed rule probably being a load of old rubbish, but The Invoker remained adamant that everybody knows about the Five Second Rule, and that it was only a biscuit anyway.

Asking around on Twitter and at work confirmed that there are plenty of people out there who’ve heard of the rule, although the time boundaries seem to be flexible depending on location, and many people seemed to think that it was probably incorrect, but followed it anyway. This, obviously, makes no sense at all.

It sound like an urban myth, and in my experience, when things sound like urban myths, they normally are.

It seems common sense to expect that food that comes into contact with an unclean surface would pick up traces of whatever made the surface unclean in the first place, and there’s been plenty of research done to prove just this.

A paper published in the Journal of Applied Microbiology (links to .pdf)  investigated the Five Second Rule in some detail, and concluded that salmonella could survive for up to four weeks on a dry, hard surface.

That’s a long time.

Even worse is the finding in the same paper that 99% of bacteria present on a floor tile were transferred onto a piece of bologna during five seconds of contact.  That’s just normal, resting contact…they didn’t use the bologna like a mop, it was just put on the tile.

This isn’t the whole story, though.

There’s huge variation in bacteria transfer levels depending on the type of food and the type of surface it lands on.  Generally speaking, a piece of bread landing on carpet is probably going to be OK, but a slice of ham landing on a kitchen floor isn’t.  Anything in between is likely to show a sliding scale of contamination – it seems that the harder the surface and the wetter the food, the bigger the problem.

That’s all relative, though, because it doesn’t take much salmonella or e-coli to make you seriously ill and the transfer of some pathogens between surface and food happens immediately on contact.  This makes perfect sense – as food impacts a surface, it is bound to pick things up easily and immediately.  Try this for yourself by sprinkling some caster sugar on the floor and dropping a piece of ham on top of it.  The sugar will stick to the ham, even if you pick it up immediately.

Now, imagine that those specks of sugar clinging to your ham are salmonella.

Still feel hungry?

Another factor to think about is the condition of the floor the food gets dropped on.  I suspect that most kitchen floors aren’t quite as clean as their owners think they are – they’re high traffic areas susceptible to all kinds of lingering spills and stains…perfect breeding grounds for bacteria colonies.  In contrast, outdoor surfaces are very likely to be cleaner than your kitchen – sun and rain see to that – so a biscuit dropped by a child onto a pavement should be fine.  The types of pathogens present in a kitchen are more likely to be harmful than those found outside.

Think chicken blood dripping onto a kitchen floor.

I’m definitely not in favour of paranoia here – exposure to all kinds of nasties is necessary to build and maintain a healthy immune system, and the desirability of the dropped food item and their relative need to it it now are powerful factors

This isn’t about being a clean freak or wrapping your kids in cotton wool….just don’t eat ham off the kitchen floor.

And that muffin up there in the photo?  It took about ten minutes to take the shot, and after I’d done, and bearing in mind everything I’ve just written, I decided to throw it away.

What do you think?  Do you eat food that’s fallen on the floor?

{ 15 comments… read them below or add one }

Katie April 3, 2011 at 5:46 pm

I have an immune system and I trust it. Kids would crawl on that floor and then suck their thumbs/ eat a biscuit, let the dog have a bit and then eat the rest. I eat stuff I have dropped in my own house if its not visibly contaminated with dust/fluff. I probably wouldn't eat stuff dropped outside, more because its more likely to be dusty than because of germs. Plus if you blow the food that removes 99.9% of the germs FACT and I am a registered nurse so I should know.

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rich April 3, 2011 at 6:44 pm

I was saving the 'blow on food to sterilise it' rule for another post.

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Hester Casey - Alche April 3, 2011 at 7:47 pm

Interesting question! I wouldn't knock it as I'm sure exposure to a few germs helps build a strong immune system but wouldn't be keen to eat food off the floor however short a time it has spent there.

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Susan April 3, 2011 at 8:32 pm

My house has two cats, two dogs, and a husband who tromps through the woods. They all track 'it' into the house and around the floors … if it falls on the floor, it's either compost or trash. Period.

Wish I could be more easy-going, but…

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ingashaven April 3, 2011 at 9:57 pm

Haha I love this – I have heard of that rule but it´s always been the 3 – sec rule :D

it totally depends on where you drop the food – but if it´s in my own home I usually pick it up again

it sounds so bad to admit that though :/

but I have to agree w/ Susan that when I had a cat in the house it went straight to the bin

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Christina April 4, 2011 at 12:24 am

In my house it depends on 4 things…

1- What was dropped? I mean, anything sticky or unfinished OR and ingredient going into something being served to others is a definite NO.

2-Did it land face up, or face down? (if applicable of course) and

3- How much cat and/or dog hair (if any) is still on it after blowing on it (again, if applicable)…I DO try to keep the floors clean, but with 2 dogs & 2 cats… ;)

4- Can I get to it before the dogs?

So I guess my answer here is sometimes.

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Alex April 4, 2011 at 11:30 am

I'm with Katie – I have a tendency to eat stuff that's dropped in my own home (or at my parents' house!). I have a cast iron gut – don't know if that's a product of my relaxed attitude or not!

At the moment I'm spending my time sterilising bottles for a baby who spends his whole time with all sorts of non sterilised crap in his mouth. Sometimes I really wonder why!!!!!

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Matt Tempest April 4, 2011 at 2:22 pm

I have a friend who washes her hands every time before eating, and every time she returns home.

Seemed like OCD to me at first, but I wondering if that's not just sensible? I was sort of taught to wash my hands before eating as a child, but it's a habit I got out of.

(Stress: This is not about not washing your hands after toilet, gardening, heavy manual work etc where they're obviously "dirty".)

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Stephanie April 4, 2011 at 2:58 pm

Looks like you've done your research and some interesting comments. Thanks for sharing.

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The Chocolate Priest April 4, 2011 at 11:37 pm

I remember they did an episode of "Myth Busters" about this and found out a lot of other things are much worse than eating food you dropped on the floor.

We can't protect our kids or ourselves from everything in this world, we have to take risks, I think it comes down to what you personally think is acceptable risk. For me it depends on when it happens. If I recently cleaned or not, the type of food, the expense of it, the mood I'm in.

To claim otherwise would be to lie.

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David April 12, 2011 at 1:34 pm

3 seconds max. That allows sufficient time to retrieve said foodstuffs before it is possible for germs to get into gear; and that's a FACT!

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Tamar April 14, 2011 at 5:01 am

Our country's germaphobia is part of the reason that many Americans have developed so many allergies and have lower resistance to diseases than our fore-bearers. I figure as long as your floor/carpet is reasonably clean and the food that fell on the floor doesn't have lots of moisture, just pick it up, dust it off and eat it.

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Sasa April 18, 2011 at 10:45 am

We don't have shoes in the house (Japanese) and apparently that's one of the best things you can do in your home to improve health…I eat stuff off the ground because I'm convinced it is good for my immune system but I wouldn't outside or in someone else's house probably.

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Jenny Eatwell April 18, 2011 at 11:12 am

It depends entirely upon the state of the floor and what it is that I've dropped. In your graphic ham/sugar example, no – anything dropped would either go in the dog or the bin. However, if I drop a slice of aubergine or a pork chop on the kitchen floor that was about to go in the frying pan, then yes – it gets a quick run under the cold tap and straight into the frying pan. I reckon whatever it's picked up gets killed before it can even formulate an action plan, let alone get to work. However, cooked meat products dropped in the same situation go in the dog.

Having said all of that, however, I remember a very dear horse-owning friend (whose carpets were always a combination of hay/straw/horsehair/dog hair, no matter how often she vacuumed), who spent the afternoon laboriously cooking a glorious lasagne. She served the family and sat down in front of the t.v. to tuck into her portion – and the doorbell went. Her five dogs immediately went into vertical takeoff and the biggest (greyhound) knocked her plate flying. Naturally, it landed upside down on the floor. She came back from seeing to whoever it was at the door, to find three of the dogs licking up whatever they could access from around the plate. Having shooed them off, and picked up the plate, she discovered the majority of her lasagne was untouched. So scraped it back onto the plate, removed any hair or fluff and got on with it again. She said "I was so disappointed that I'd lost my dinner, I wasn't going to give it up in a hurry when it looked okay". She lived to tell the tale. ~shrug~

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Hortense October 21, 2011 at 1:53 pm

There is only 1 rule for me: dropped ? toss it.

Even when something falls off in my appartment. There is dust (even if I can’t see it), hairs and I am sure I walked with my shoes all over every single inch of my appartment. No surface but my plate is completely clean

Of course if I am cooking, I’ll cook it again, won’t toss it.

If something drops to my clothes, the same rule: drop it: my clothes have been everywhere outdoors and I sit almost everywhere.

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