MONDAY, Jan. 6, 2003 (HealthDayNews) -- Juvenile delinquency is often blamed on neglectful parents, lousy neighborhoods and poor schools.
New research reveals a startling possibility for the root of much of the bad behavior: exposure to lead.
Researchers tested the lead bone concentrations of 194 youths aged 12 to 18 convicted in the Allegheny County Juvenile Court in Pennsylvania and 146 students in regular high schools in Pittsburgh who did not have behavioral problems.
The study found delinquent children were four times as likely to have elevated concentrations of lead in their bones.
The mean concentration of lead in the convicted youths was 11.0 parts per million, compared to only 1.5 parts per million among other high schoolers.
Based on their findings, researchers attribute an estimated 11 percent to 38 percent of juvenile delinquency in Allegheny County to lead exposure.
"This study suggests a substantial proportion of delinquent behavior is due to a preventable cause -- lead," says Dr. Herbert Needleman, lead author of the study and a University of Pittsburgh professor of child psychiatry and pediatrics. "Very small amounts of lead are associated with toxicity."
The study appears in today's issue of Neurotoxicity and Teratology.
Needleman is one of the world's leading researchers on lead poisoning and children. He authored a groundbreaking 1979 study that found children with high levels of lead in their teeth, but no outward signs of lead poisoning, had lower IQ scores, shorter attention spans and poorer language skills.
Despite laws that banned the use of lead-based paint in 1978, lead exposure is still a major public health problem, says Dr. Dana Best, an assistant professor of pediatrics at George Washington University and medical director of the Children's National Medical Center.
The major source of lead exposure is deteriorating paint from older houses or from dust and soil contaminated with lead from older paint. Lead was used as a drying agent and to make colors brighter, Needleman explains.
More than 80 percent of U.S. homes built before 1978 have lead-based paint, according to the U.S. Centers for Disease Control and Prevention (CDC). The older the house, the more likely it is to contain lead-based paint.
Lead poisoning, which can occur if children eat paint chips, can cause severe headaches and convulsions.
However, children don't have to eat paint chips to suffer lead exposure. Lead from old paint gets mixed into the dust in the house, and children ingest it when they put their fingers or toys in their mouths, Needleman says.
About 890,000 children aged 1 to 5 have elevated levels of lead in their blood, the CDC estimates. About 22 percent of black children living in housing built before 1946 have elevated blood lead levels.
For decades, parents have reported to pediatricians that their children's behavior changed after they were lead poisoned. Parents said their children became irritable, overactive and aggressive, he says.
Doctors still don't know exactly what lead, a neurotoxin, does to the brain to cause the cognitive and behavioral changes.
In 1996, Needleman published a study of 300 boys in public schools. It found that teachers and parents were more likely to report boys with high levels of lead in their bones engaged in antisocial activities such as bullying, vandalism, truancy and shoplifting.
The recommended safety level is no more than 10 micrograms per deciliter of blood, according to the CDC.
However, new research is showing that even children whose blood levels fall below that level have a small but statistically significant decrease in IQ, Best says.
"What we are learning is there is no safe level of lead," Best says.
In Allegheny County, public health officials say the study points to the need for renewed efforts to make sure children are safe from lead exposure.
Public health officials regularly set up clinics in grocery stores that offer free blood tests for lead exposure in children under 6. Years ago, testing turned up about 150 cases a year. In the last few years, that number has dropped to about 75 children a year, says Dave Zazec, an Allegheny County Health Department spokesman.
"If Dr. Needleman's study is corroborated, we are going to have to go back to the community and the medical community and put this issue back on the front burner," Zazec says. "Let's press the issue and make sure children at risk are screened for lead."
Lead poisoning is preventable. If you're concerned about your family's lead exposure, the CDC has this advice:
- A simple blood test can determine if your child has been exposed.
- If you live in a house or apartment built before 1978, contact your state or local health office about testing paint and dust in your home.
- Use a damp mop to clean floors and other surfaces. Frequently wash children's hands, pacifiers and toys.
- Use only cold water from the tap for drinking, cooking and making baby formula. Hot water is more likely to contain higher levels of lead.
What To Do
For more information, check out the U.S. Centers for Disease Control and Prevention or the American Academy of Pediatrics.
