May 28, 2008 -- Lead shrinks children's brains, a long-term study strongly suggests. The damage is permanent.
The findings come from the Cincinnati Lead Study, which recruited pregnant women living in neighborhoods with historically high rates of childhood lead poisoning. The study measured kids' lead exposures throughout childhood and then gave 157 of them MRI brain scans when they were 19 to 24 years old.
None of the kids in the study had lead poisoning, according to the researchers.
University of Cincinnati spectroscopist Kim M. Cecil, PhD, and colleagues found that the more lead a person had in his or her blood as a child, the more certain parts of their brains shrank.
The shrinkage was in the gray matter of the brain, in areas linked to problem solving, selective attention, complex motor control, error detection, decision making, regulation of personal and social behavior, and emotional control.
These effects were particularly strong for males. Other human and animal studies show that males are especially sensitive to the harmful effects of lead.
"We found that early childhood lead exposure is associated with structural volume loss in the brain," Cecil and colleagues conclude. "Our findings are consistent with, and potentially explanatory for, long-observed behavioral findings in children and adults with a history of lead exposure."
In an editorial accompanying the report in this week's issue of the online journal PLoS Medicine, Harvard child neurologist David C. Bellinger, PhD, notes that while the study does not prove that childhood lead exposure causes brain damage, it rings a shrill alarm.
"The associations observed by Cecil and colleagues provide a clear warning sign that early lead exposure disrupts brain development in ways that are likely to be permanent," Bellinger writes.
In a second article in PloS Medicine, University of Cincinnati criminologist John Paul Wright, PhD, and colleagues find that higher childhood blood lead levels are linked to a higher risk of arrest for violent crime.
"We conclude that these data implicate early exposure to lead as a risk factor for behaviors leading to criminal arrest," Wright and colleagues write.