Although, one could argue, this depends upon your definition of dangerous. If you're talking battle-torn war zone, then yes, perhaps just about any shounen world, although, I'm not really a particular fan of the shounen realm.
I would consider a world like Ranma 1/2 to be pretty dangerous. Not only are you surrounded by complete idiots, but also there's the various transformation curses, on top of all the random martial arts -- performed by certifiably nut jobs! That sounds pretty dangerous to me. And of course one can not forget about all the treacherous love triangles within that realm. The phrase "Hell knows no fury, like a woman scorn", is a complete understatement here.
However, there's a major caveat here. Are we talking about a regular mortal human being like you or I being thrown into such chaos, or are we talking about throwing a random non-realm anime character into a world? Or, are we just talking about keeping canon pure, and only the characters already within a world being dangerous. Because, the third option could technically be argued that most anime worlds are inherently dangerous from the perspective of the character's point of view.
And there I go, getting all philosophical before my first cup of coffee. Relax, Senkusha, everything's gonna be just fine!