lead, crime and teen pregnancy

Leaded gasoline peaked around the year I was born, and both crime and teen pregnancy peaked while I was a teenager. I managed to steer clear of these two things (or maybe I left no evidence in either case…), but maybe I would have been the next Einstein if it weren’t for lead, we’ll never know.

Lead Exposure and Behavior: Effects on Antisocial and Risky Behavior among Children and Adolescents Jessica Wolpaw Reyes NBER Working Paper No. 20366 August 2014

It is well known that exposure to lead has numerous adverse effects on behavior and development. Using data on two cohorts of children from the NLSY, this paper investigates the effect of early childhood lead exposure on behavior problems from childhood through early adulthood. I find large negative consequences of early childhood lead exposure, in the form of an unfolding series of adverse behavioral outcomes: behavior problems as a child, pregnancy and aggression as a teen, and criminal behavior as a young adult. At the levels of lead that were the norm in United States until the late 1980s, estimated elasticities of these behaviors with respect to lead range between 0.1 and 1.0.

Maybe we learned our lesson with lead and mercury and have moved on. Or maybe something as bad or worse is hiding in plain site in our consumer products and we just haven’t figured it out yet.

Just for the archives, here is a key 2000 study by Rick Nevin on the subject: How Lead Exposure Relates to Temporal Changes in IQ, Violent Crime, and Unwed Pregnancy.

This study compares changes in children’s blood lead levels in the United States with subsequent changes in IQ, based on norm comparisons for the Cognitive Abilities Test (CogAT) given to representative national samples of children in 1984 and 1992. The CogAT norm comparisons indicate shifts in IQ levels consistent with the blood lead to IQ relationship reported by an earlier study and population shifts in average blood lead for children under age 6 between 1976 and 1991. The CogAT norm comparisons also support studies indicating that the IQ to blood lead slope may increase at lower blood lead levels. Furthermore, long-term trends in population exposure to gasoline lead were found to be remarkably consistent with subsequent changes in violent crime and unwed pregnancy. Long-term trends in paint and gasoline lead exposure are also strongly associated with subsequent trends in murder rates going back to 1900. The Andings on violent crime and unwed pregnancy are consistent with published data describing the relationship between IQ and social behavior. The Andings with respect to violent crime are also consistent with studies indicating that children with higher bone lead tend to display more aggressive and delinquent behavior. This analysis demonstrates that widespread exposure to lead is likely to have profound implications for a wide array of socially undesirable outcomes.

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