The “3-second Rule” experiment

Image: Wikimedia commons (Click on image to see source)

I have a confession to make. When I look at online news-sites, I’m not looking for “real” news, I’m looking for unusual headlines. These are normally found on the SciTech pages (as they always seem to involve some kind of “scientific research”) of the less serious (for want of a better term) news-sites. Often, it’s either the research which is of a dubious nature – or the discussion of the results by reporters who don’t really understand science too well.

If I come across anything interesting, I’ll usually do a search to find out where the story originated – and if it is true. Otherwise, I just read the story for it’s amusement value and don’t take anything I read too seriously. [This is the motto of Laura’s Unlikely Explanations, which offers similar entertainment value! In the case of Laura’s blog, you just relax and enjoy reading as her explanation (and sometimes even the original story) are completely made up.]

I’ve got a couple of these intriguing and/or disturbing stories to share with you . . . The first is:

The “3-second rule” experiment – some know this as the “5-second rule”

Would you, if you drop some solid foodstuff on the floor, snatch it up and eat it as long as it hasn’t been there for longer than 3-seconds? Or do you, like my friend Riekie (when I told her about this), go “Ew, NO way”? Well, now you need wonder no more if it is safe to do this as . . .

Five food items were tested by Manchester Metropolitan University (MMU) to see whether the three-second rule could be trusted.

Bread with jam, cooked pasta, ham, a plain biscuit and dried fruit were all dropped on the floor and left for three, five and 10 second intervals.

These were selected as they are commonly eaten foods and all have different water activity levels; a key factor in whether items will sustain bacterial growth in the three seconds before they are picked up from the floor.

After the study, the foods were examined to ascertain whether or not harmful bacteria found on the floor was then found to be growing on the dropped food.

The study revealed that dropped foods with a high salt or sugar content were safer to eat after being retrieved, as is less chance of harmful bacteria surviving on such items.

Eating processed food from the floor poses the lowest risk – one of its few benefits – given that it generally contains such high levels of sugar and salt.

Both the ham, a salty product, and the sugary bread and jam fared well in the test. When retrieved from the floor within three seconds, the foodstuffs showed little sign of bacterial growth.

[From: MailOnline]
You might want to avoid picking up and eating cooked pasta or dried fruit though . . . And another factor to consider would be the cleanliness of your floor. According to the scientists this means mopping your floor daily and changing your mop head every 3 months.
On researching this topic further, I’ve discovered several other similar experiments, but the most entertaining so far is the one I saw on Mythbusters a while back . . .
The five-second rule was also featured in an episode of the Discovery Channel series MythBusters. There was no significant difference in the number of bacteria collected from 2 seconds exposure as there was from 6 seconds exposure. The moisture, surface geometry and the location the food item was dropped on did, however, affect the number of bacteria.
From: Wikipedia
Good to know! Of course I never have to make that choice. Rosie (our dog) is usually in the kitchen with me when I’m preparing food, and snaps up whatever hits the floor – in less than 3 seconds!

Tags: , , , ,

Categories: Food/Cooking, Random


I live on the Southern coast of South Africa, and write about the things that interest, amuse or inspire me. You can find me at and (my photoblog)


Subscribe to the Notes from Africa RSS and Twitter feeds to receive updates.

15 Comments on “The “3-second Rule” experiment”

  1. May 18, 2012 at 4:15 pm #

    I have no worries–two dogs picking up anything either Sara or I drop! Forget the vacuum, folks, get a dog!

  2. May 19, 2012 at 6:48 am #

    Our cat Tallulah used to be good for this too, particularly if it was something she fancied.

    • May 21, 2012 at 7:20 am #

      Hi Debra! Hope you’re well. Cats are so much more discerning. Our cat will only eat her own food off the floor. Or tuna. 🙂

  3. May 19, 2012 at 11:25 am #

    My cats almost never eat anything I drop on the floor. They will bat it around, though. That probably doesn’t make it any safer to eat.

    • May 21, 2012 at 7:20 am #

      Yes, maybe it wouldn’t be a good idea to eat it after they’re finished playing with it! 🙂

  4. May 19, 2012 at 3:16 pm #

    My love little doggie girl is my combination mop and crumb buster. I’ve never had to test that rule 🙂

  5. May 20, 2012 at 5:06 pm #

    With Reggie around, I wouldn’t even get a chance to conduct this experiment. He’s much faster than I am. He can hear a breadcrumb hit the kitchen floor from the bedroom!

    • May 21, 2012 at 7:25 am #

      Hi Jackie! From all the comments I’ve read about the 3-second rule not being an issue with dog owners, I can only gather that those that worry about it do not have dogs.

      PS: In case you’re wondering: I am still following your blog. Have been reading your posts on my phone – still want to go back and comment on them . . .

      • May 22, 2012 at 4:31 pm #

        That’s so nice, Lisa! I hope to see you more often around the blogosphere soon.
        Since it’s heading into fall there, I hope you’re feeling like your old self again!

  6. May 21, 2012 at 2:32 am #

    I have a variation on the 3 second rule. If it`s sticky and it drops- I won`t eat it. Of course something sticky will pick up bacteria no matter how long it`s on the ground right? BUT- if it`s not sticky- chip, popcorn,a dry carrot stick something not wet – I might let it stay down there for up to 6 seconds before I pick it up and eat it. My theory being bacteria can`t adhere to it as easily.
    However- movie theatre floors, baseball parks and places where animals and people trod all day long are exceptions to the sticky rule and I will not eat anything that falls.

    • May 21, 2012 at 7:29 am #

      Hi Emily! Really glad to hear that you don’t eat off the floor in public places. 🙂 Moisture content does seem to have a role in the development of bacteria, so like you I will pick up some “dry” stuff. Maybe not popcorn and chips though – the dog will get those – but especially things I can wash off. My main concern is usually: when did I last clean the floor!

  7. June 4, 2012 at 10:19 am #

    I’ll admit that I wouldn’t even abide by a 1-second rule. Is it because I know I don’t mop that regularly? 😉

    • June 5, 2012 at 7:27 am #

      Ah yes, that would be my problem too – if it weren’t for Rosie, the dog! 😉

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: