What a topic and what all answers, really intersesting.
Which is safer? (neglecting the protective mechanisms)If you are going to touch a live line of 220V, it is going give you double the current. ie, Current is proportional to Voltage(Potential difference),in this case the Potential difference between the line and the ground. Your body resistance is the same( Say a constant 'R') for both the cases.
By Ohm's law V=IR
or I=V/R, where V is voltage, I is Current and R is resistance.
so at 110V I=110/R and
at 220V, I=220/R ie 2x(110/R).
So, it means that at 220V you will get double the current. ie, Europeans will get double the electric shock as compared to an American when he touches accidently the Live(hot) wire by accident.
But if you are wet, your 'R' goes down and you are dead.
The other things like heating and current will be more for 110V for appliances but it safer from an electric shock point of view.
Actually 110V can be considered as a luxury because it's accessories are going to be more expensive as it has to handle double the current.