The violence from the crack epidemic wasn't because people were using crack (crackheads don't commit a ton of murders, really) it was because there was sort of a "land grab" for new crack dealers resulting in a lot of turf wars until the situation stabilized and/or communities got fed up by the gang violence.
The reason why the crack epidemic reasoning makes more sense as a causitive agent is because violent crime didn't simply go down in the '90s as leaded gasoline was phased out. Rather, crime increased dramatically in the '80s and early '90s before peaking and falling. That doesn't match either the profile of lead exposure nor the population of the folks who typically commit violent crimes (sub 30 year old males). In fact, there was a peak of violent crime among 14-24 year olds as a percentage of that population group that matches the onset of the crack epidemic perfectly but does not match lead exposure or socio-economic status well at all.
The figures there back up the premise that there was a wave of new and exceptional violence caused by young gang bangers fighting in the streets over the crack business.
The reason why the crack epidemic reasoning makes more sense as a causitive agent is because violent crime didn't simply go down in the '90s as leaded gasoline was phased out. Rather, crime increased dramatically in the '80s and early '90s before peaking and falling. That doesn't match either the profile of lead exposure nor the population of the folks who typically commit violent crimes (sub 30 year old males). In fact, there was a peak of violent crime among 14-24 year olds as a percentage of that population group that matches the onset of the crack epidemic perfectly but does not match lead exposure or socio-economic status well at all.
Here's a good graph that highlights just that: http://en.wikipedia.org/wiki/Gun_violence_in_the_United_Stat...
The figures there back up the premise that there was a wave of new and exceptional violence caused by young gang bangers fighting in the streets over the crack business.