Nicotine - very, very bad!
Here's something I didn't know. It's possible for a young child to die from nicotine poisoning after eating a single cigarette butt. That's pretty toxic. In fact, a lethal dose of nicotine is 20 times smaller than a lethal dose of cocaine. This suggests that people should be more careful with cigarettes around children, but strangely enough it appears that seeing Janet Jackson’s nipple is more dangerous for children than seeing people smoke. Strange that. You'd think young children wouldn’t mind nipples at all.
Anyway, nicotine is supposed to be toxic. When insects eat tobacco plants they die from the nicotine. It's a form of chemical warfare. It's just chance that it also happens to be an addictive stimulant for mammals. Back in my grandfather's day you could buy nicotine in a tin to use as an insecticide. But they ended up banning it on account of how people had a tendency to use it to gain inheritances, get rid of annoying family members and so on. How typical of interfering bureaucrats to get in the way of innovation in family management! Gardeners also had a tendency to wake up anxious and irritable with an almost uncontrollable urge to go and kill aphids.
Oh, and apparently the majority of people with schizophrenia smoke. Not sure what's going on there. It may be an attempt to self medicate in much the same way as most people who suffer from work drink coffee.