This is closely related to the 70 yards? 80 yards? thread in a lot of ways. I don't see as much of a saftey issue with such shots as I do a responsibilty to the game we hunt.
Here is a quote from Gobblerman from that thread which I agree with-
> the chances of an animal being wounded and then escaping, without a doubt, increase as the distance between the hunter and the animal increases. This holds true pretty much regardless of the type of game being hunted. <
As for the shot itself, "more dangerous" must be first intepreted that it applies to humans instead of game. A shooter is responsible for positively identifying his target and being sure of his backdrop at any range, be it 40 yards or 80 yards, so there is nothing to argue there.
Where the argument usually does insue, is that this is all relative to where you hunt or take such a shot. In an area where you are reasonably sure you are the only one there, or the only one that should be there, an 80 yard shot is not inherantly more dangerous to humans. I say "the only one" because this applies to all humans, not just hunters... mushroom seekers, hikers and bird watchers can all be part of the equation. In a public area with much greater opportunity for human contact of all sorts, a longer shot is always going to be "more dangerous," it's more difficult to be sure of your backdrop and the shot angle is going to be higher.
To recap this messay (mini-essay), there is too much relativity involved to provide a definite conclusion. "More dangerous" is a relative generalization, and it is directly relative and subjective to the area or region where the principle is being applied.
I'm not sure why any of this would be baffling to anyone, it's all physics...but as with anything else, logic must be employed during the application.
"The joy of living is his, who has the heart to demand it." Teddy Roosevelt