Criminal Intent: Could Lead Exposure Be to Blame?
Published June 2008
For years, we’ve know that lead is toxic to the nervous system. Early exposure to the metal has been implicated as a risk factor for developmental delays and behavioral problems in childhood and adolescence.
Now scientists are pointing the finger at lead in a new area—criminal intentions.
UC researchers have reported the first evidence of a direct link between prenatal and early-childhood lead exposure and an increased risk for criminal behavior later in life.
Kim Dietrich, PhD, and his team have determined that elevated prenatal and postnatal blood-lead concentrations are associated with higher rates of criminal arrest in adulthood.
“Previous studies either relied on indirect measures of exposure or failed to follow subjects into adulthood to examine the relationship between lead exposure and criminal activity in young adults,” explains Dietrich, principal investigator of the study and professor of environmental health at UC.
“We have monitored this specific sub-segment of children who were exposed to lead both in the womb and as young children for nearly 30 years,” he adds. “We have a complete record of the neurological, behavioral and developmental patterns to draw a clear association between early-life exposure to lead and adult criminal activity.”
Dietrich says few studies have attempted to evaluate the consequences of childhood lead exposure as a risk of criminal behavior. The UC-led study is the first of its kind to demonstrate an association between developmental exposure to lead and adult criminal behavior.
Dietrich and his colleagues report their findings in the May 27, 2008, issue of the journal PLoS Medicine.
This new study is part of a long-term lead exposure study conducted through the Cincinnati Children’s Environmental Health Center, a collaborative research group that formed in 1979 and involves scientists from the UC College of Medicine and Cincinnati Children’s Hospital Medical Center.
Led by Dietrich, researchers recruited pregnant women living in Cincinnati neighborhoods
with a higher concentration of older, lead-contaminated housing. Recruitment took place at four prenatal clinics between 1979 and 1984.
Dietrich’s team has monitored this population group since birth to assess the long-term health effects of early-life lead exposure.
Of the original 376 newborns recruited, 250 were identified for the current study. Researchers measured blood-lead levels during pregnancy and then at regular intervals until the children were 6 1/2 years old to calculate cumulative lead exposure.
Blood-lead level data was then correlated with public criminal arrest records from a search of Hamilton County, Ohio, criminal justice records. These records provided information about the nature and extent of arrests and were coded by category: violent, property, drugs, fraud, obstruction of justice, serious motor vehicle, disorderly conduct and other offenses.
Researchers found that individuals with increased blood-lead levels before birth and during early childhood had higher rates of arrest—both for violent and nonviolent crimes—than the rest of the study population after age 18.
Approximately 55 percent of the subjects had at least one arrest—the majority of which involved drugs (28 percent) or serious motor vehicle violations (27 percent). However, the strongest association was observed between childhood blood-lead levels and crimes involving acts of violence.
Dietrich says that although both environmental lead levels and crime rates in the United States have dropped in the past 30 years, they have not done so in a uniform way.
“Lower income, inner-city children remain particularly vulnerable to lead exposure,” he explains. “Although we’ve made great strides in reducing lead exposure, our findings send a clear message that further reduction of childhood lead exposure may be an important
and achievable way to reduce violent crime.
“Aggressive or violent behavioral patterns often emerge early and continue throughout life,” adds Dietrich. “Identifying the risk factors that may place youth on an early trajectory toward a life of crime and violence should be a public health priority.”
UC coauthors include John Wright, PhD; Douglas Ris, PhD; Richard Hornung, PhD; Stephanie Wessel; Bruce Lanphear, MD; Mona Ho; and Mary Rae, PhD. Funding for the study came from grants from the National Institute of Environmental Health Sciences and the U.S. Environ-mental Protection Agency.