There&#x27;s been a lot of research lately on the connection between lead, brain impairment, and violence.<p>One quick example, claiming cities in the 1920s that switched to lead pipes saw ~25% increase in homicides vs those that didn&#x27;t. <a href="http:&#x2F;&#x2F;scholar.harvard.edu&#x2F;files&#x2F;jfeigenbaum&#x2F;files&#x2F;feigenbaum_muller_lead_crime.pdf" rel="nofollow">http:&#x2F;&#x2F;scholar.harvard.edu&#x2F;files&#x2F;jfeigenbaum&#x2F;files&#x2F;feigenbau...</a>