LA's Rise And Fall Of Violent Crime, And The Explanation For It

It peaked in the early 1990s, then fell just as swiftly and sharply. Violent crime fell -- all over the country -- to about half its peak level by the mid-teens. It has continued to stay relatively low, with something of an upswing in this post-Covid-lockdown era, but it has not returned to anything like the peak levels of the 1990s, or even close to those levels. 

It turns out that we now have an explanation for the rise and fall of violent crime, and it isn't the efforts of police chiefs or elected politicians or even police commissioners. We have an explanation for the concerns about "super-predators" and why we no longer need to have such concerns. We also have a reason to expect that violent crime will not increase again, whether or not we elect anybody in particular to high office. 

The effect of leaded gasoline on the young brain 

In the early years of this new century, a few researchers became aware of a curious and striking coincidence: The addition of tetraethyl lead to gasoline and the much-increased level of driving in the postwar years was strongly correlated with an increase in violent crimes about 20 years later. 

(The increasing crime rate had a political effect: As crime continued to rise, politicians and police became increasingly loud about the problem (and as the data show, not without reason), and some began to predict that we were in for an era of super-predators if we did not do something. The result was the passage of laws that increased sentences, in parallel with Supreme Court decisions that gave the police increased latitude to stop you, search you, and immobilize you for their own protection. As much as this offended civil libertarian sensibilities, there was some reason behind such changes.) 

But since the early 1990s, that rise in crime has reversed itself. 

A local blogger, Kevin Drum, took note of the research on leaded gasoline and crime rates, and began to publicize the studies. He wrote an article for Mother Jones magazine in 2012, which you can find here.  

As the data clearly show, crime all over the country rose and fell coincident with children's exposure to lead from leaded gasoline. It takes about 20 years for the resultant crime to manifest itself, because it is in the teens and young-adulthood that people -- even those predisposed to lack of self-control from an early age -- commit the most crimes. 

There is a rational biological explanation for this link between lead exposure and gasoline, which has to do with a part of the brain that lead exposure affects in a particularly bad way. 

Here is one excerpt from a detailed discussion: 

"The biggest source of lead in the postwar era, it turns out, wasn’t paint. It was leaded gasoline. And if you chart the rise and fall of atmospheric lead caused by the rise and fall of leaded gasoline consumption, you get a pretty simple upside-down U: Lead emissions from tailpipes rose steadily from the early ’40s through the early ’70s, nearly quadrupling over that period. Then, as unleaded gasoline began to replace leaded gasoline, emissions plummeted. 

"Intriguingly, violent crime rates followed the same upside-down U pattern. The only thing different was the time period: Crime rates rose dramatically in the ’60s through the ’80s, and then began dropping steadily starting in the early ’90s. The two curves looked eerily identical, but were offset by about 20 years." 

Drum wrote an update in 2018 which discussed the accumulating evidence for the lead-crime hypothesis, and which also deals with attempts by criminologists (and others) to downplay the effects of lead on juvenile crime. You can find it here. I would recommend that you look at the first graph in this article, which shows the correlation between leaded gasoline usage and violent crime after taking into account the 20 year time lag. 

Los Angeles was equally affected 

During that same period, crime in the city of Los Angeles fell, just as it was doing in other big cities. You can see the trends here.  

In other words, the falling crime rate in Los Angeles was not due to the work of mayor Jim Hahn, or the new police chief Bill Bratton, or police commissioner Rick Caruso, or, for that matter, any of our other local politicians such as Mike Feuer, or individual policemen such as Joe Buscaino. I doubt whether we could credit other politicians such as Karen Bass either. Crime fell all over the country. It also rose and fell in other countries in correlation with their introduction and cessation of the use of lead in gasoline. In other words, the argument that lead in gasoline results in untoward social effects including murder is by now well demonstrated. The decrease in crime we saw starting in the early 1990s had little or nothing to do with whether the police followed Bratton's policies or did nothing in particular. It simply followed the increase and then decrease in brain damaged children as they grew to adolescence and then adulthood. 

Limitations to this argument and a caveat 

Television news has been all over a recent increase in smash-and-grab robberies and follow-home assaults, along with brazen attacks on people eating lunch in sidewalk locations. These are crimes which require planning and forethought. They are intentional and, to a certain extent, rational, because they are ways for crooks to make money. There is nothing in this whole line of thinking that would argue against increased efforts by the police and prosecutors to catch the criminals and prosecute them publicly in order to create some additional level of deterrence. 

Public policy questions and issues 

One serious question is whether we, the voters, should elect candidates who continue to hammer on the threat of violent crime in an era when crime has been on a steady downward trend. The counter to that inquiry is that there has been a sudden upward tick in crimes in this post-lockdown period. Is it merely a temporary condition that is due mainly to the economic effects of the Covid period, or is it something else? In any case, we are not in an era like the 1980s where the crime rate was on a steady, upward course. The efforts of the right wing and the efforts of those who parrot the right wing ought to be taken with a large grain of salt. 

Another issue is that we need to learn from the lead-crime story. We need to be careful about the dangers of poisoning ourselves and our children with other neurotoxic substances. 

Mainly, we ought to be careful about letting corporate interests get away with dangerous acts just because they have political clout. Modern automobile engines run just fine without the addition of tetraethyl lead to their fuel sources. It is highly likely that the automobile companies could have built engines that ran without lead additives even in the 1940s and '50s, just as they had for the first half of the 20th century. Somebody should have stopped them sooner rather than later. The same argument can be applied to efforts by wealthy corporate interests to stem efforts to prevent global warming. In each case, the desire to make money, left uncontrolled, has led to catastrophic results.

(Bob Gelfand writes on science, culture, and politics for CityWatch. He can be reached at [email protected])