Twice the voltage will push twice the current through your body. Since your body resistance is far too high for even 220 to push 7 Amps, that breaker will not blow.
In any case, it isn't the current that kills, it's the fact it's AC. The 60-Cycle (Hz, for you newbies) frequencey messes up your heart beat, so only a few miliamps is probably enough to kill you, but 220 will do it more surely than 110 under less than ideal conditions.
Using 220 volts instead of 110 is purely a matter of using less copper, not safety.