All those times that you picked food off the ground and thought it was cool? Sorry, you just ate a bunch of bacteria. At least that's the story scientists have to tell you.
We've all had our run ins with the urban myth that is the 'five second rule', and the majority of us have probably picked up a fallen piece of food and dusted it off with a little blow before eating thinking that all would be well but it turns out we were wrong.
Research from the University of Illinois has shown that bacteria can in fact be transferred from surfaces onto food in less than five seconds with contact times of three to 30 seconds allowing plenty of time for bacteria to hop around, but it all depends on how dirty the surface is and what kind of surface it is.
Defining 'dirty' is difficult, but it really only takes 0.1% of cells on a surface to make you unwell (and only ten cells of E. coli can make you ill).
As for surfaces, the biggest surprise is that carpet is actually better to drop food on than wood or tiled floors. Carpet dosed with Salmonella transferred less than 1% of the bacteria when food was dropped on it, whereas the same food picked up 48% to 70% of the bacteria when it was dropped on tiled and wooden surfaces.
Not quite time to start lining your entire home with carpet, but at least next time that last bite of food falls onto the floor you'll know what you're in for.