Over 50V DC starts putting you in the risky area:
http://en.wikipedia.org/wiki/High_voltage
Some meters have high voltage warnings at greater than about 38V or so IIRC.
The IEC standard of <120V is crazy high IMO!
If you got two sharp needles and stuck them through your rib cage into your heart and then applied 12 V across them it might kill you...everything is relative. The only safe voltage is no voltage