Here’s a new "lead pollution causes bad behavior" study by Jessica Wolpaw Reyes using National Longitudinal Study of Youth 1979 and NLSY97 data. I reviewed her first attempt on this important topic back in 2007 in “ Lead Poisoning and the Great 1960s Freakout .”

Now by comparing self reports and parental reports of behavior problems in the NLSY studies versus state results of average lead levels in blood, she finds more support for the lead > bad behavior, but less so for lead > violent crime nor for lead > black bad behavior. This is big news because it helps explain why Robert Heinlein’s 1939 prediction that the 1960s-1970s would be the Crazy Years turned out pretty accurate, but it shoots down explanations for the black-white crime gap based on putative lead pollution.

LEAD EXPOSURE AND BEHAVIOR EFFECTS ON ANTISOCIAL AND RISKY BEHAVIOR AMONG CHILDREN AND ADOLESCENTS Jessica Wolpaw Reyes Abstract 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. “These are sizable elasticities, suggesting a substantial effect of early childhood blood lead on criminal behavior as a teenager. To assess effects on more specific crime categories, I construct two (non-comprehensive) sub-categories: violent crime, comprised of assault and robbery, and property crime, comprised of theft, burglary, destruction of property, and other property offenses.56 For violent crime, the results are insignificant. For property crime, the elasticity is significant in the NLSY79 sample but not in the NLSY97 sample. ….

“To investigate these factors in the NLSY data, I perform the above analyses separated by parental education (less than high school vs. high school vs. college or more), income (less than twice the poverty line vs. more than thrice the poverty line), and race/ethnicity (black or Hispanic vs. white). I find that, while all children are harmed by lead, advantaged groups are harmed more by lead.

The estimated effects of lead are larger and more consistently significant for children whose parents are more highly educated, whose families have higher income, or who are white. For the education and income breakdowns, this divergence between advantaged groups and disadvantaged groups is particularly apparent when looking at lead’s effects on child behavior problems. In order to understand this result, recall that lead from gasoline was ubiquitous in the 1980s: it was in the very air children breathed, and everyone was affected regardless of income, education, or race. While children in more advantaged families might have been protected from many of the adverse environmental or social influences that children in disadvantaged families had to contend with, they were not protected from gasoline lead. Thus, whereas for the disadvantaged children lead may have been just one more adverse influence (on top of numerous others), for many of the advantaged children it was perhaps the only or the primary adverse influence. In a way, the advantaged children had more to lose. Consequently, gasoline lead may have been an equalizer of sorts.”

Yet one of the more obvious differences between Chicago’s black and white areas is the heavier traffic in the expensive, safe zones. People who can afford cars tend to move away from black slums, leaving them bleak. In the Chicago area, race and class palpably determine the homicide rate. For example, compare the next-door neighbors Oak Park and Austin west of The Loop. The Eisenhower Expressway runs through Oak Park, but not through Austin. Yet the homicide rate is several dozen times worse in Austin. [Kevin] Drum, who lives in Irvine, at least should be familiar with Southern California, where South-Central is fairly light in traffic compared to the jammed freeway interchanges of upscale West LA and Sherman Oaks. And across the country, the densest neighborhoods are typically the various Chinatowns, which suffer little street crime and enjoy high math scores.

Note that the story for paint lead may be substantially different, since paint exposures are likely to follow the familiar pattern whereby the disadvantaged suffer greater exposure and the advantaged are largely insulated.

Indeed, gasoline lead seemed to hurt middle class white children more than poor blacks:In other words, this might explain why times at Ridgemont High were so fast in the 1970s compared to the 1930s — the movie was filmed in Sherman Oaks at the shopping mall right at the Ventura (101) and San Diego (405) freeways, the busiest freeway interchange in America for much of the era. But, this data can’t support the idea that blacks were hurt worse by gasoline lead pollution than whites were:That’s what I wrote a awhile ago in Taki’s : lead might have been a major cause of what Heinlein predicted to be The Crazy Years, but it doesn’t explain why blacks have worse average civic order before during and after the Lead YearsReyes goes on:But fears of poor children eating lead paint flakes off the walls were a big deal in the newspapers in the middle of the 20th Century. In Chicago , liberals argued for tearing down old tenements and constructing giant high rise public housing projects like Cabrini Green specifically to cut down on poor children’s exposure to lead paint.

How’d that work out?

I’d add that Reyes should watch out for statistically assuming that the amount of lead spewed into the atmosphere by cars roaring about is the causal variable on more risky, more liberated youth behavior. It could be that cars themselves were what were causing youths in states with lots of driving to behave in less old-fashioned ways by getting them out from under the supervision of elders.

A measure of gasoline lead pollution in a state also serves as a measure of the number of automobiles and the number of miles driven in a state, which over the course of the 20th Century tended to correlate with loosening strictures on the behavior of young people, who were off gallivanting about doing who knows what in the back seats of their cars. See American Graffiti and countless other movies for details

For most of the 20th Century, for instance, California tended to be car crazy and tended to lead the country in youth trends, a point made by Tom Wolfe in his first breakthrough essay The Kandy Kolored Tangerine Flake Streamline Baby. As noted brain chemical researcher Brian Wilson pointed out:

And she’ll have fun, fun, fun Until her daddy takes the T-Bird away