Airborne Lead is a componant of wood smoke, and is ingested just by breathing.
Many earlier studies have reported that low level lead exposure isassociated with lower intelligence and more violent behavior in children ( Journal of the American Medical Association 1996;275:363-369, Environmental Health Perspectives 1997;105: 956-962). A New Jersey study of 705 pregnant women found that higher blood lead levels were associated with significantly higher levels of hypertension and toxemia in pregnancy. Results were adjusted for age, calcium intake, race and socioeconomic factors.
- Maryfran Sowers et al. Blood lead concentrations and pregnancy outcomes. Archives
Part of society's recent increase in violence may be due to lead poisoning. According to a study by Herbert Needleman of the University of Pittsburgh School of Medicine and colleagues published in February in the Journal of the American Medical Association, boys with higher bone-lead levels are more likely to be aggessive and delinquent.
"This is probably the most critical study that has been done on lead in the last five years," says Janet Phoenix, manager of public health programs at the National Lead Information Center of the National Safety Council, an international public interest organization. "The social implications are enormous."
Lead has been linked with behavioral problems since the early 1940s, when pediatrician R.K. Byers noted that some children he had treated for acute lead poisoning subsequently developed violent, aggressive behavioral difficulties such as attacking teachers with knives or scissors. Needleman's study, supported in part by the NIEHS, is the first to link asymptomatic levels of lead with aggressive behavior and delinquency.
Needleman and his colleagues studied 301 boys from primary schools in Pittsburgh. The researchers measured bone-lead levels by K X-ray fluorescence when the boys were about 12 years old. Based on the relative lead content of their tibias, the boys were divided into high- and low-lead groups. Bone-lead levels reflect lifetime exposure to lead because, like calcium, lead is stored in bones. The boys in the high-lead group had normal levels of lead in their blood by the time of the study, showing that their lead exposure had occurred in the past.
The researchers evaluated the boys' behavior at 7 and 11 years of age based on reports from three sources: the boys themselves, their parents, and their teachers. These data were from widely respected tests of antisocial behavior that had been administered by the Pittsburgh Youth Study, a longitudinal study of the developmental course of delinquency. At 11 years, the boys were given a self-reported delinquency interview, which comprises 35 questions such as how many times in the past six months a subject has "been drunk in a public place" or "attacked someone with a weapon." The parents and teachers filled out the child behavior checklist, which contains 113 symptoms of childhood behavioral disorders such as cruelty or bullying, shoplifting, setting fires, and apparent lack of guilt after misbehaving.
When the high-lead boys were 7 years old, neither they nor their parents reported significant behavioral problems, and their teachers reported only borderline tendencies toward symptoms such as social problems, delinquency, and aggressive behavior. By the time these boys were 11, however, they reported significant increases in antisocial acts, and their parents and teachers reported significant increases in symptoms such as delinquent and aggressive behavior. The researchers corrected for confounding factors such as the mothers' intelligence, the presence of the father, and socioeconomic status.
Many U.S. children have toxic bone-lead levels and--provided that their results are found to extend to the population at large--Needleman and his colleagues conclude that lead makes a substantial contribution to delinquent behavior. Other researchers hail the Needleman study as the first to rigorously demonstrate a link between lead and antisocial behavior. The study was well-designed and its implications are likely to be valid, according to Terrie Moffitt of the Department of Psychology at the University of Wisconsin at Madison. Self-reporting is trustworthy when the period reported on is less than a year, the interviews are private and face-to-face, and confidentiality is guaranteed, she says, and the Needleman study met these conditions. Furthermore, Needleman's conclusions are strengthened by the fact that reports from three sources--the boys, their parents, and their teachers--all linked lead with antisocial behavior.
Lead is a neurotoxin and human studies indicate that its neurological effects are likely to be irreversible. However, delinquency is also associated with factors such as weak parent-child attachment, lax parental supervision, and school failure. Addressing these issues can mitigate the effects of lead. "These kids need help. They need support from teachers and parents," says Phoenix. "No one knew they were lead-poisoned." The good news is that environmental lead exposure can be avoided. "Lead-related delinquency is the easiest to prevent," says Needleman. "We should be able to wipe this disease out by removing old lead-based paint."
[Ed. And stopping wood burning. Believing that just removing lead based paint will solve the problem is part of the problem. Parents should also be concerned with protecting children from lead in wood smoke.]