It's not the seconds that count. I watched Myth Busters and learned what matters is whether or not the food is 'dry' or 'moist/wet/sticky'. Moisture picks up germs and other particles. Dry, for the most part, does not, unless it lands on a wet surface (yuck).
If you drop a jellied piece of toast, and it lands 'jelly side' down, no, toss that shit out.
But, if when you drop it, it lands 'dry toast side' down, yes, you can most likely still eat it.
I would also take into account the cleanliness of the surface on which it landed.