It is in a descriptive sense, but not in terms of establishing causation.
Naturally occurring. What would be more interesting is to look at the health of those in the areas. My guess is that it would be fine. There are lots of “poisons” in our food that are natural but have been found to be helpful for us in combating or preventing disease. Broccoli has natural pesticides in it. Broccoli sprouts, in reliable scientific studies, have been found to help fight bladder cancer. So before we help fix a problem, it would be nice to see if there really is one.