Just a non-scientifc opinion: I think it binds to the rain/the humidity and does go into the ground, yes. Depending on where your water comes from, it might not seep into that, I think. And stuff in your lungs may be worse than the same stuff in your stomach, depending on the stuff, I guess.
What I really came to say: the only long term solution is guillotines
I’m seriously not trying to be antagonizing, but help me out on the logic of number 5. I mean, indigenous tribes fought and conquered each other countless times, everywhere over the world, right? So how is that different from Europeans/whichever civ conquering them?