Actually, with cocaine, nicotine, and heroine, all are drastically changed from plant form to finished product. Marijuana is the one that stays in the form that it grows in, which is what I mean by natural, though I do agree with you that there are a lot of natural toxins in the world, such as most mushrooms. But marijuana is hardly toxic. And in some cities, breathing the air is pretty bad, and can have some long-lasting effects, but I will give the point to you on that one since, for the most part, it's not as big of an issue these days with the tightened regulations.
for ADHD, they had me on Silert when I was a kid. Turned out I didnt have ADHD at all, because I was still able to pay attention to things, I was just hyper. Silert, now, is a nightmare to the company that produced it.