Roe vs Wade:

1973

While yes, it's most likely not a significant factor in the drop in crime:

https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis#%3A%7E%3Atext%3DA_2007_report_published_by%2C%25_decline_in_violent_crime%22.?wprov=sfla1

Systematic reviews / meta-analysis

The first meta-analysis of the lead-crime hypothesis was published in 2022. "The Lead-Crime Hypothesis: A Meta-Analysis", authored by Anthony Higney, Nick Hanley, and Mirko Moro consolidates findings of 24 studies on the subject. It found that there is substantial evidence linking lead exposure to a heightened risk of criminal behavior, particularly violent crimes. This aligns with earlier research suggesting lead exposure may foster impulsive and aggressive tendencies, potential precursors to violent offenses. The study concluded that, while a correlation between declining lead pollution and declining criminality is supported by research, it is likely not a significant factor in reduced crime rates, and that the link is generally overstated in lead-crime literature.

The study's implications point towards the potential benefits of reducing lead exposure to decrease crime rates. Such reductions could be achieved through initiatives like removing lead from products like gasoline and paint, water pipes and enhancing lead abatement measures in schools and residences.