The rate of violence in US schools has
been declining
for 20 years, following the decrease in lead in gasoline.
The multiple killings every week or two are shocking, but don't amount
to a lot of victims compared with the other sorts of violence among
teenagers, and that has been going down in the US.
Even small amounts of lead make children less intelligent. That leads
them to be violent, because sometimes they can't see a better
response. But lead-induced stupidity would affect all sorts of
decisions, including voting. I wonder if the effects of lead
poisoning lead people to believe right-wing "solutions", such as
Reagan's "trickle-down", and the idea that cities ought to lure
businesses away from other cities by offering them subsidies.