An interesting article here about increased violent crime among people exposed to lead as children. In fact, they can chart the decrease in crime connected to when states made the transition from leaded to unleaded gasoline.
I stabbed myself with a lead pencil as a child, right in the thigh.
In high school, when California made the transition to unleaded gasoline, I had to buy lead supplements so that my Chevy Nova could keep running.
But if anyone said I became violent because of those two things... well, I'd poke them right in the eye.