The 5 Second Rule

I’m sure we have all heard the five second rule at some point in our lives, and it states that if you drop food on the ground, you’ll have five seconds to pick it up and still be able to eat it. Obviously if you drop something outside or on a very dirty floor, you should not eat it because the food will definitely be dirty, however I was curious to see if there was some truth to this myth. If food was dropped on a normal floor, I wondered if it would actually take five seconds for germs to accumulate on it.

A study was done by Jillian Clarke to determine if this myth is true. She covered floor tiles with E.coli and then dropped gummy bears and cookies onto the contaminated floor. She removed the food from the floor after five seconds and observed that a lot of bacteria had gotten onto the food despite the fact that it was only on the floor for five seconds. This experiment shows that the five second rule is not true because bacteria still managed to get on the food within five seconds.

A concern about this experiment may be that floors will not be as dirty as the one Clarke used, and that for the most part floors are kept relatively clean, especially in houses which is where the five second rule is most commonly used. A study done by the Hygiene Council showed that common kitchen floors have a lot of bacteria on them. They have 830 per square inch, which is double that of inside a trashcan. This shows that floors are usually dirty and that bacteria would contaminate the food.

These two studies provide pretty solid evidence that the five second rule is not true. Bacteria clearly got onto foo within five seconds, and floors contain enough bacteria for this to happen. Based on this I would not trust the five second rule and I recommend that nobody else does too despite who says its okay or how good the food looks.

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5 thoughts on “The 5 Second Rule

  1. Naseem Memari

    I have been hearing people scream the 5 second rule ever since I was little. I never was quite sure why we decided or who decided it was 5 seconds but I never questioned it. I’m glad you looked up the ideas behind the 5 second rule because I did not know the data you shared!

  2. Casey Patrick Brennan

    I actually did a blog on the same topic, and I found the same result as you. The experiment I analyzed used bologna and Salmonella. The main result from that experiment was that
    1. The five second rule is a myth
    2. It doesn’t matter how long the food is on floor, but rather how long the bacteria has been on the surface. The longer the bacteria has been living on the surface, the chance it transfers decreases exponentially. It should really be the five second rule for bacteria, not food.

  3. Imaani Allen

    The five second rule was something that I never belived in. My mom taught me that once it reaches the floor its dirty no matter what. It really bothers me to see young kids eating food off the floor in public and the moms don’t even care. Do they not know that there are miilions of germs on the ground that could get their kid sick. The five second rule is a myth whoever started it should be ashamed of themselves.

    1. Devon Buono

      I’m glad you commented, even though you stated that you disagreed with my findings. My blog was stating that 5-seconds is too long, and germs transfer much sooner than the 5-second mark. I did not write about the contamination level affecting the amount of germs transferred. In your defense, I did not mention that the amount of bacteria present is also a factor in how contaminated the food will become. The Experiment I posted about did mention that the amount of bacteria present effects the transfer rate. That is why they measured the amount of bacteria present before starting the experiment(In an effort to limit third confounding variables). They stated that surfaces with a smaller reading of germs, is going to transfer a smaller amount of germs. Thanks for the comment.

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