WASHINGTON (Reuters) -
Exposure to lead in early childhood
or in the womb can cause permanent brain damage that may even
cause criminal behavior, researchers reported on Tuesday.

Two studies showed that people with high levels of lead in
childhood grew up with blocks of missing brain cells — and
they also were far more likely to be arrested for crimes,
especially violent crimes.

The effect is so strong that it may account for a large
percentage of crimes in inner-city areas, where old houses are
far more likely to have lead paint, said Kim Dietrich of the
University of Cincinnati in Ohio, who led one of the studies in
the Public Library of Science journal PLoS Medicine.

“There are some data that suggest that in fact lead does
run in parallel with crime trends over the past several
decades,” Dietrich said in a telephone interview.

Dietrich and colleagues signed up pregnant women living in
Cincinnati neighborhoods ridden with lead-contaminated housing
between 1979 and 1984. They tested the women and then their
children from birth and have been watching the children as they
grew up.

They correlated blood-lead level data from 250 of the
children to criminal arrest records.

Those with high lead levels before birth and during early
childhood had higher rates of arrest than those with lower lead
levels. About 55 percent of the now-grown children had at least
one arrest, 28 percent involving drugs and 27 percent serious
motor vehicle violations.

“Lower income, inner-city children remain particularly
vulnerable to lead exposure,” Dietrich said.

“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.

MISSING BRAIN CELLS

His colleague Dr. Kim Cecil of Cincinnati Children's
Hospital Medical Center did magnetic resonance imaging, or MRI
scans, of the brains of their volunteers.

They found more than 1 percent of total gray matter in the
brain was missing. “The most affected regions included frontal
gray matter, specifically the anterior cingulate cortex,”
Cecil's team wrote in a second study. This region is
responsible for mood regulation and decision-making.

Men were far more affected than women.

“Our findings also suggest that this structural change is
permanent,” they wrote.

The implications are profound, Dietrich said. “Usually the
effects of lead poisoning are irreversible,” he said.

Environmental enrichment programs such as those used to
help children who are abused may help, he added. “I don't think
they are lost but it certainly is a warning,” he said.

Lead paint is by far the biggest source of poisoning, he
said — despite recent U.S. scares involving lead in water, in
imported toys and in folk medicine.

The mothers of the children likely had lead in their bodies
from their own childhoods, and exposed their babies in the
womb, he said.

“Many also grew up in these neighborhoods,” Dietrich said.

In a third, unrelated study, a team of University of
Pittsburgh researchers showed adults can be inoculated with a
second wave of lead as they get older.

Writing in the Archives of Environmental and Occupational
Health, Lisa Morrow and colleagues showed that lead can leach
into the blood from bones as people age and lose bone mass.

(Editing by Eric Walsh)