Back in the Stone Ages (~1967) I was working with image-intensifying vacuum tubes and one setup had a 30KV Spellman bench supply, maybe a milliampere or so. I took a few shocks from that, including one from the eyepiece of the microscope I was using to examine the image right to my eyebrow -- knocked me across the room, but I'm still here to tell about it. The amount of current needed to kill varies widely with the path the current takes thru the body. Naturally it takes less if it enters near the heart than if it's in the legs. I'm sure there's plenty of information on shock hazard limits on the web.
Norm