Let‘s be honest, it happened to everyone of us at least once. You spread some delicious "Insert what you love here" on your bread and you are ready to satisfy your hunger. Just as you want to take your bite the toast falls out of your hand. In almost slow-motion you see your toast flying towards the ground. On a rotating basis you see the side with the Nutella and the empty one. What happens? It drops right on the side with the Nutella. 5...4...3...2...got it! Under five seconds and you are good to go. Is this true, is it okay to eat food that we picked up under five seconds?

We will bring light into this myth and see if there is any truth behind.

Fig.1 Some bad, bad germs on some crisps. Credits

The rule

The rule states that if food drops to the floor and is pick it up within five seconds, it is not contaminated and edible. Bacteria and other germs will not have your health affected when the food is picked up within five seconds. Myth or fact? There were indeed two scientific study to this question.
The first study is by Jillian Clarke from the University of Illinois. In a survey he found out that about 56% of male and 70% female knew about the five second rule and stick to the it. He further proved that food became immediately contaminated when having contact with a contaminated surface. His work was the basis for the second study. The team around Paul L Dawson from the University of Clemson did three experiments to determine whether or not bacteria contaminated food. For this experiment they used bolognese and bread and let the food drop to different surfaces like wood, carpet and tile.

The results are clear: the moment the food has contact with the surface the bacteria have transferred. The only difference made the variable of time which determines the amount of bacteria which settle on the food. The longer the contact with the surface the higher the amount of germs actually. Further they showed, that the transfer from floor to food was higher on the wood and tile surface than the carpet. Another main result is that bacteria can survive up to 28 days on certain surfaces. The bacteria used in this experiment were salmonellae.

What does that mean to you
While the time might be important, the five second is not. The amount of bacteria is ten time higher when food was over one minute in contact with the floor compared to some seconds. Food becomes immediately contaminated, no matter how long it was in touch with a surface. However, if you keep your house clean it is unlikely to find any pathogen germs around and you can enjoy your food even when it touched the ground. Still, consider that if you are outside or in dirty areas, it is much more likely to find harmful germs. The five second rule is nothing more than a myth and no fact.

I hope you enjoyed the first episode of Myth or Fact. The next one will follow tomorrow.
-Tim

Source of the scientific study:
Residence time and food contact time effects on transfer of Salmonella Typhimurium from tile, wood and carpet: testing the five-second rule