50 Kv with enough current to feel is lethal force. Period. All you need are a couple of breaks in the skin in the right places, maybe some blood or other conductor, and the game is over.

I can't find the safety documents at Fluke, but cautious EE's start paying attention at 50v and even the insane ones are paying attention by 500v. It doesn't take much current to disrupt the heart at all: all you need to do is get a little voltage difference in the right place...

And as I recall there have been several documented Taser deaths in Europe.