An increasingly popular theory among realist centrists such as Kevin Drum has been that the rise in the crime rate in the 1960s-1970s wasn’t due to the liberal policy and politics of the era, but lead pollution from leaded gasolines. Then the murder rate suddenly dropped sharply in the second half of the 1990s because kids then had been born after leaded gasoline began to be phased out in 1975 America.

In the decade that I’ve been writing about it, I’ve found this theory interesting but likely overblown.

Did the effects of lead get 30% worse from 2019 to 2022?

Now there’s a meta-analysis of lead-crime studies and its conclusion is in line with my thinking: The lead-crime connection is not unimportant but not that important either. From Regional Science and Urban Economics:

The lead-crime hypothesis: A meta-analysis☆
Anthony Higney, Nick Hanley, Mirko Moro

Does lead pollution increase crime? We perform the first meta-analysis of the effect of lead on crime, pooling 542 estimates from 24 studies. The effect of lead is overstated in the literature due to publication bias. Our main estimates of the mean effect sizes are a partial correlation of 0.16, and an elasticity of 0.09. Our estimates suggest the abatement of lead pollution may be responsible for 7–28% of the fall in homicide in the US. Given the historically higher urban lead levels, reduced lead pollution accounted for 6–20% of the convergence in US urban and rural crime rates. Lead increases crime, but does not explain the majority of the fall in crime observed in some countries in the 20th century. Additional explanations are needed.

The centerpoint of a range of 7% to 28% is 17.5%, which isn’t negligible but isn’t dominant either.

[Comment at Unz.com]