Current draw depends on your resistance. The safe contact voltage on automotive systems is based roughly on this principle. I think in the US the maximum allowed voltage is 60V, in Europe it is 50 or 55V. I don't think it takes much current to cause damage -- I want to say mA (milliamps) of current is all it takes but I don't remember. If your heart is in the path of the current, it can cause some serious damage.
On most academic laboratories you won't see dc voltages any higher than +/-15V, so the highest differential is 30V and I think this is OK for the OSHA standard in the US.
Be very careful with any high voltages and proceed with caution.
Best regards,
v_c