There was an interesting article posted a while back showing a strong correlation between crime and the levels of lead in the environment most notably from lead

There was an interesting article posted a while back showing a strong correlation between crime and the levels of lead in the environment most notably from leaded gasoline. The theory is that the reason crime has been dropping so much is because leaded gas was outlawed and it has taken the better part of the past couple decades for those bad effects to wear off. http://www.motherjones.com/environment/2013/01/lead-crime-link-gasoline http://www.motherjones.com/environment/2013/01/lead-crime-li...