An overview article over at Brookings got posted up a few days ago, going over a few recent papers an article providing even more evidence that lead poisoning dramatically increases crime rates and that it's been having a deeply pernicious effect on our societies worldwide.
https://www.brookings.edu/blog/up-front/2017/06/01/new-evidence-that-lead-exposure-increases-crime/
In the article, they link to a recent Reuters article that focuses primarily on Los Angeles- http://www.reuters.com/investigates/special-report/usa-lead-la/ that's worth reading in full on its own.
In addition, three recent studies are highlighted-
If you're looking for more information on the subject, Kevin Drum's excellent Mother Jones piece gives an overview of why this hypothesis has gained so much traction so quickly - http://www.motherjones.com/environment/2016/02/lead-exposure-gasoline-crime-increase-children-health
He's also been doing frequent updates on his blog before and after this piece regarding this subject,and there was a recent update regarding a professor's 2008 prediction about UK crime rates - http://www.motherjones.com/kevin-drum/2017/02/violent-crime-peaked-britain-2006-because
As a bonus- here's the original 2007 study on lead poisoning that kicked this all off - http://pic.plover.com/Nevin/Nevin2007.pdf
And a WaPo article about it - http://www.washingtonpost.com/wp-dyn/content/article/2007/07/07/AR2007070701073.html
https://www.brookings.edu/blog/up-front/2017/06/01/new-evidence-that-lead-exposure-increases-crime/
In the article, they link to a recent Reuters article that focuses primarily on Los Angeles- http://www.reuters.com/investigates/special-report/usa-lead-la/ that's worth reading in full on its own.
In addition, three recent studies are highlighted-
One of these papers
considers the aggregate effects of lead exposure on city-level crime, using U.S. data from the early twentieth century. The authors, James Feigenbaum and Christopher Muller, noted that one of the primary ways individuals were exposed to lead during this period was by drinking water pumped through lead pipes. But not all cities had lead pipes. If a city was far from the nearest lead refinery, it would likely have pipes made from another material. Comparing places with and without lead pipes might allow us to estimate the effect of lead exposure on crime, but wed worry that places near lead refineries are systematically different in some way that could confound our estimates: perhaps theyre subject to more pollution, or are wealthier. To address this, the authors exploit another interesting fact: lead only seeps into water when the water is acidic. This sets up a nice natural experiment that sorts otherwise-similar cities into the treatment and control groups we need. Those with lead pipes and acidic water are the treatment group (their populations were exposed to lead in the drinking water). Cities with lead pipes but non-acidic water, and cities with acidic water but non-lead pipes, are the control groups. These control groups account for the independent effects of lead pipes or acidic water and whatever characteristics those features are correlated with. Using this experiment, the authors measure the effect of lead exposure on homicide rates lagged by 20 years (to give the kids exposed to lead time to grow up). They find that exposing populations to lead in their drinking water causes much higher homicide rates 20 years later, relative to similar places where kids avoided such exposure.
The next paper does just this, using data from more recent years. Anna Aizer and Janet Currie
link data on preschool blood lead levels with data on school suspensions and incarceration, for children born in Rhode Island between 1990 and 2004. They note that kids who happened to live closer to busy roads within a neighborhood are more likely to have high blood lead levels, because the soil near those roads was still contaminated due to the use of leaded gasoline decades ago. This was especially true for kids born in the early 1990s, as environmental lead levels have fallen over time. They use those kids as the treatment group (high lead exposure) and similar kids who lived on other roads, as well as kids who lived on the same roads in later years, as the control group. These kids look similar in most other ways they attend the same schools, their parents have similar incomes, and so on so we would expect them to have similar outcomes. But Aizer and Currie find that being exposed to higher levels of lead increases kids likelihood of suspension from school as well as (for boys) the probability of being incarcerated as juveniles. The magnitude of their estimates suggest that the reduction in lead exposure due to the switch to unleaded gasoline may indeed explain a substantial portion of the decline in crime in the 1990s and 2000s.
The third paper comes at the lead-crime hypothesis from a different direction, and asks whether government programs that aim to reduce lead exposure can protect kids from leads negative effects. Stephen Billings and Kevin Schnepel
measure the effect of CDC-recommended interventions for kids with elevated blood lead levels. Kids who test above a certain lead level twice in a row are provided intensive services including lead abatement in their home and nutritional counseling to mitigate the effects of lead exposure. The reason two tests are required is that blood lead tests are extremely imprecise. There are therefore a lot of kids who test over the threshold once but not the second time, for reasons other than their actual lead exposure. Billings and Schnepel use the noise in these test results as random variation that divides kids into treatment and control groups: kids who tested over the threshold twice get these services, while kids who tested over the threshold once and then just below the threshold the second time do not. The intuition is that these kids have similar blood lead levels, but due to random noise in the test, some are treated and others are not. By comparing what happens to those two groups of kids, Billings and Schnepel are able to measure the effects of CDC-recommended interventions on kids outcomes.
They use data on kids born between 1990 and 1997 in Charlotte-Mecklenburg County, North Carolina. The data include results of blood lead level tests as well as school records and adult arrests. They find that, relative to the control group, kids who receive the intervention exhibit substantially less antisocial behavior, including suspensions, absences, school crimes, and violent crime arrests. These results are striking for two reasons: (1) The kids blood lead levels low by historical standards are high enough to affect their behavior and put them at risk for suspensions and arrests. (2) The CDC-recommended interventions have a big impact and can substantially mitigate those risks. The authors conclude: It is likely that increasing the frequency and intensity of intervention for lead-exposed children will yield a profound return considering the potential long-term effects of lead on health and human capital.
If you're looking for more information on the subject, Kevin Drum's excellent Mother Jones piece gives an overview of why this hypothesis has gained so much traction so quickly - http://www.motherjones.com/environment/2016/02/lead-exposure-gasoline-crime-increase-children-health
He's also been doing frequent updates on his blog before and after this piece regarding this subject,and there was a recent update regarding a professor's 2008 prediction about UK crime rates - http://www.motherjones.com/kevin-drum/2017/02/violent-crime-peaked-britain-2006-because
Professor Robert Waldmann's 2008 prediction said:n April 2008, I predicted that the UK violent crime rate would peak some time around 2008. I just googled and found that it peaked in around 2006 or 2007.
Note two things here. First, Britain's violent crime rate peaked about 15 years after it did in the US. Second, it dropped a lot faster than it did in the US. Why?
Because, first, Britain adopted unleaded gasoline about 13 years after the US (1988 vs. 1975). And second, because it phased out leaded gasoline a lot faster than the US. Within four years Britain had cut lead emissions by two-thirds, which means there was a very sharp break between infants born in high-lead and low-lead environments. Likewise, this means there was a sharp break between 18-year-olds with and without brain damage. In 2006, nearly all 18-year-olds had grown up with lead poisoned brains. By 2010, that had dropped substantially, which accounts for the stunning 40 percent drop in violent crime in such a short time.1
This is one of the reasons the lead-crime hypothesis is so persuasive. Not only does recorded crime fit the predictions of the theoryboth in timing and slopebut it does so in many different countries. What other theory would predict a gradual drop in violent crime between 1991-2010 in the US and a sharp decline in violent crime between 2006-10 in Britain? Especially considering that the US and Britain have entirely different policing, poverty rates, race issues, etc.?
As a bonus- here's the original 2007 study on lead poisoning that kicked this all off - http://pic.plover.com/Nevin/Nevin2007.pdf
And a WaPo article about it - http://www.washingtonpost.com/wp-dyn/content/article/2007/07/07/AR2007070701073.html