All the blood in your body passes that point on the wrist in just about 45 seconds. As long as the voltage is correct you will get the approx 100 to 200uA of current flow in the blood. Getting the electrodes in the right spot is critical. Going accross the heart could cause problems especially if you have an undiagnosed heart condition. The currents that Dr, Beck talk about are just for going the short distance on the wrist. If I was going the larger distance I would do it on the same side (ex:on right hand & right foot)just to be safe. Its too bad no one will do the research on different points on the body and the required voltage & current for those other points. You could hav a dual electrode running, left side and right side at the same time but with a safety of not going across the heart.