So how much credit would you give the rule that if drop food but pick it up within 5 seconds, it's still safe to eat?

Is it true?

Our bodies are quite good to getting rid of bacteria and other nasties that may make us ill in our food. There's no science to the 5s rule as far as I know. If there's something nasty enough to make us ill then less than a second will do it. If there isn't then even 10-15s won't do it.