Economist Rick Nevin finds evidence that lead abatement may account for falling violent crime rates in recent years. Nevin was interviewed for an article in WAPO:.
"I began with the city that was the crime capital of America," Giuliani, now a candidate for president, recently told Fox's Chris Wallace. "When I left, it was the safest large city in America. I reduced homicides by 67 percent. I reduced overall crime by 57 percent."
Although crime did fall dramatically in New York during Giuliani's tenure, a broad range of scientific research has emerged in recent years to show that the mayor deserves only a fraction of the credit that he claims. The most compelling information has come from an economist in Fairfax who has argued in a series of little-noticed papers that the "New York miracle" was caused by local and federal efforts decades earlier to reduce lead poisoning.
The theory offered by the economist, Rick Nevin, is that lead poisoning accounts for much of the variation in violent crime in the United States. It offers a unifying new neurochemical theory for fluctuations in the crime rate, and it is based on studies linking children's exposure to lead with violent behavior later in their lives.
What makes Nevin's work persuasive is that he has shown an identical, decades-long association between lead poisoning and crime rates in nine countries.
"It is stunning how strong the association is," Nevin said in an interview. "Sixty-five to ninety percent or more of the substantial variation in violent crime in all these countries was explained by lead."
Through much of the 20th century, lead in U.S. paint and gasoline fumes poisoned toddlers as they put contaminated hands in their mouths. The consequences on crime, Nevin found, occurred when poisoning victims became adolescents. Nevin does not say that lead is the only factor behind crime, but he says it is the biggest factor.
Two popular explanations, aging and teen unemployment rates, were also considered, but only lead exposure accounted for a significant and large amount of variation in violent crime rates ( page 2):
Nevin tested the effect of childhood lead exposure and the effect of teen unemployment, the overall unemployment rate, and the proportion of the population in age brackets associated with higher crime rates (ages 15 to 25). Nevin’s statistical analysis found that childhood lead exposure explained 88% of the variation in the overall violent crime rate, while teen unemployment explained just 2%. The effect of overall unemployment and the proportion of the population in younger age brackets were found to be insignificant. Only childhood lead exposure was found to have any significant effect on changes in the rate of aggravated assault, which accounts for about 60% of all violent crime.