Just several hundred mA of dc current through the chest area is lethal, so please take some care when measuring body impedance. It may be just a tale, but it is told that a physics professor carefully inserted hypodermic needles in each wrist, then applied a 'traditional' VOM using a 9v transitor battery for power. Death was instantaneous.
The truth is that body fluids are a saline solution and offer rather low impedance. Net body impedance is a function of skin thickness (such as callous or not), presence of a wound or not, presence of perspiration, age and so on. And the body is very sensitive to the frequency of voltage applied. Stimulation at near heart rhythm is more likely to induce fribillation than dc or high frequency.
