AC-DC

You have to qualify that with a voltage level and current. 5VAC and 5VDC are equally harmless, unless it is 1000A at 5V, then both are dangerous. 5000VAC and 5000VDC are equally fatal even at the 1A level.

Anytime I see that "And why?", that's almost a guarantee of a homework question.

So, I'll ask you a question which also answers your question. Are you interested in cooking the human body or simply killing it?

As per IEC 60479 (Guide to the effects of currents in human body), to produce the same effects of 0.5mA AC Current (i.e.) perception threshold, you need 3.5mA DC Current. And, 6mA AC gives painful shock whereas you need 41mA DC to have the same effect on you.

So, definitely DC Current of the same magnitude and flowing for the same duration as the AC Current is definitely less dangerous than the AC Current.

ElectricalExpert65:

You have provided data on DC and AC current for perception and pain threshold, but this information alone is not enough to know with certainty that the current required for serious damage or death exhibit a similar relationship...

The amount of sodium chloride in your mouth required for perception and the amount required for pain (yes I think I could find an amount that would hurt), would be far less than the amount of sodium cyanide required for perception (you might sense something akin to bitter almond if you are genetically predisposed) or the amount required for pain...if an amount exists for NaCN.

But the same relation does not hold for damage or death.

I'm not saying that your conclusion isn't correct. I'm saying the evidence you have provided does not rule out a different conclusion. We may be more adept at sensing AC, just as we are more adept at tasting table salt...without bearinmg on the relative danger thereof.

Benbenben

That's kind of the point I was making.

Are you more dead from 500VAC than you are from 500VDC?