Criminologist Peter Stretesky looked at the murder rate between 1989 and 1991 for all 3,111 counties in the continental United States, and then he compared the number of homicides in each county to the amount of lead present in the air. Cities with high lead levels, like Los Angeles, Detroit and Dallas, also had higher murder rates, he found. While 34 percent of the counties didn't record a single homicide in 1990, large cities with high lead levels reported many. Medical researchers have long known that high lead levels can cause hyperactivity, reduced IQ and impaired growth in children. Stretesky's research indicates that lead's legacy may last for years, predisposing some of its victims to increased aggression and violent crime.
Poverty plays a huge role in crime and violence.
But the presence of lead in the air in these cities may be one of the reasons why poverty is related to crime. Stretesky's study appears in this month's Archives of Pediatrics and Adolescent Medicine . Lead is readily absorbed into the body through air and water and is particularly toxic to the developing brains and bodies of children under the age of 6. While lead in paint and gasoline has been banned in the United States for more than 20 years, the metal is still present in water pipes and in lead-based paint in older homes. Lead also is found in dangerous concentrations around smelters, battery plants and factories that process lead.