There's been a lot of research lately on the connection between lead, brain impairment, and violence. One quick example, claiming cities in the 1920s that swit

There's been a lot of research lately on the connection between lead, brain impairment, and violence. One quick example, claiming cities in the 1920s that switched to lead pipes saw ~25% increase in homicides vs those that didn't. http://scholar.harvard.edu/files/jfeigenbaum/files/feigenbaum_muller_lead_crime.pdf http://scholar.harvard.edu/files/jfeigenbaum/files/feigenbau...