Guideline to Measure Body Resistance

British Standard 7671.

That's up to you pal! I'm not volunteering to find out

The resistance is mostly due to the dryness of the skin. Under that we Humans are just big bags of conductive electrolyte. I'd expect the resistance doesn't vary much depending on the path, but the severity of injury does.

I once heard about someone being electrocuted by their 12V car battery after they'd been swimming in the ocean. I've never been able to verify the story, but it sounds plausible.

I know nothing about established guidelines, but for many years as a science teacher, I would let everyone in the class grip the leads of an Ohmmeter (Thumb and forefinger of each hand), and tell them their resistance. The results commonly varied by 2 orders of magnitude, from about 5KΩ (for a nervous, sweaty-skinned person) to about 500kΩ ( for a calm, oily-skinned person).

I most nearly fit the latter category...

I agree with your first paragraph, and the first half of the second, but from there on I do NOT.

Skin resistance varies immensely from one individual to another, and with the contact area, among other factors. I just measured mine with two different ohmmeters (DMMs), and could not get a reading on scales below 2MΩ. My resistance was between 0.5 and 2MΩ, depending on the area of contact and the amount of squeeze pressure on the test leads. Of course this is measured using a voltage of less than one Volt. I don't have time right now to set up an experiment to measure it at higher voltages, but I have done so many times in the past. In my experience (done many times), with dry skin, most people can not feel the presence of a DC voltage below about 60V.

"...at 220v a current of 220mA will flow.This is fatal in all cases." This is obviously wrong, as I am very much alive! I have been shocked numerous times by 120VAC, several times by 220VAC, and at least once by 480VAC. Over 60 years ago, I was thrown across a small room and left briefly unconscious by a 120VAC shock from hand to wet bare feet, yet the 480V shock only made me yelp a bit, as it was a very small area of contact (a single strand of wire poking through the insulation) to the back of my hand.

Of course I have also been shocked numerous times by 15kV or so from Cathode Ray tubes (never intentionally), and many times by tens of thousands to several hundred thousand Volts from Van de Graaff and Wimshurst machines (usually intentionally).

It is, of course, wise to be aware of the dangers of electric shock, and indeed in lots of cases it has been fatal, but there is a big difference between intelligent respect for those dangers and total paranoia with electricity.