Scientists have actually investigated the Five-Second Rule.
The Five-Second Rule states that it's okay to eat a dropped piece of food, as long as you pick it up before you can count to five.
In 2003, a high school intern at the University of Illinois named Jillian Clarke conducted a survey and found that half the men and 70% of the women knew about the five-second rule. Jillian then conducted this experiment: first, she contaminated a ceramic tile with E. coli bacteria, then she
placed gummy bears and cookies for 5 seconds and analyzed the food: they sure were contaminated.
In 2007, professor Paul L. Dawson of Clemson University and colleagues repeated the experiment. This time, the test surfaces were tile, wood flooring, and nylon carpet; the food were bread and bologna; and the bugs were salmonella. They discovered that a) salmonella can survive for 28 days on a surface and b) in just 5 seconds, anywhere from 150 to 8,000 bacteria transferred to the food.
So what does this mean for the Five-Second Rule? Do what you like, but remember: the infectious dose (the smallest number of bacteria that can actually cause illness) is as low as 10 for salmonella and 100 for E. coli. (Source)
There's many factors that go into my decision to follow the 5 second rule or not. How hungry am I and how much do I like the food that I just dropped? What sort of surface did I drop it on and is it the last one? It's a lot to think about in just 5 seconds.
The five second rule is for food that has dropped from a height, not been placed carefully on top of a bacteria smear.
Context is everything here. Even ingesting E. coli is not *necessarily* going to make you sick. And most environmental bacteria will not make you sick. Food is not sterile.
That said, it is actually good for your immune system to be challenged occasionally. They way when you DO eat contaminated lettuce, your immune system says "Big whoop, I've seen this before. No problem." The chance of getting a major, knock-you-flat bacteria or virus from a surface you are familiar with (ie: not a public bathroom or cafeteria) is low.
its simple;
dont smear bacteria over the surface,
do it over somewhere that people might actually pick up off the floor and eat it.
btw,
"Tempscire" is right.