Lead–crime hypothesis

[2] Medical analyses of the role of lead exposure in the brain note increases in impulsive actions and social aggression as well as the possibility of developing attention deficit hyperactivity disorder (ADHD).

Those conditions likely influence personality traits and behavioral choices, with examples including having poor job performance, beginning a pattern of substance abuse, and undergoing teenage pregnancy.

Evidence that lead exposure contributes to lower intelligence quotient (IQ) scores goes back to a seminal 1979 study in Nature, with later analysis finding the link particularly robust.

[2][1][citation needed] The international process of trying to lower the prevalence of lead has been largely spearheaded by the Partnership for Clean Fuels and Vehicles (PCFV).

In discussions at the 2002 'Earth Summit', institutions under the umbrella of the United Nations vowed to emphasize public–private partnerships (PPPs) in order to help developing and transitional countries go unleaded.

[1][6] While noting that correlation does not imply causation, the fact that in the United States anti-lead efforts took place simultaneously alongside falls in violent crime rates attracted attention from researchers.

Journal of Economic Analysis & Policy, authored by Jessica Wolpaw Reyes of Amherst College, found that between 1992 and 2002 the phase-out of lead from gasoline in the U.S. "was responsible for approximately a 56% decline in violent crime".

While cautioning that the findings relating to "murder are not robust if New York and the District of Columbia are included," the author concluded that "[o]verall, the phase-out of lead and the legalization of abortion appear to have been responsible for significant reductions in violent crime rates."

"[3] In a 2013 article, Mother Jones ran a report by Kevin Drum arguing: Needless to say, not every child exposed to lead is destined for a life of crime.

[10] "The Lead-Crime Hypothesis: A Meta-Analysis", authored by Anthony Higney, Nick Hanley, and Mirko Moro consolidates findings of 24 studies on the subject.