Lead exposure in children linked to violent crime

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" The link between criminal behavior and lead exposure was found among even

the least-contaminated children in the study, who were exposed to amounts of

lead similar to what the average U.S. child is exposed to today, said

Landrigan, who was not involved in the study. "

Lead exposure in children linked to violent crime

A study finds that even low levels can permanently damage the brain. The

research also shows that exposure is a continuing problem despite efforts to

minimize it.

By H. Maugh II and Marla Cone, Los Angeles Times Staff Writers

May 28, 2008

The first study to follow lead-exposed children from before birth into

adulthood has shown that even relatively low levels of lead permanently damage

the

brain and are linked to higher numbers of arrests, particularly for violent

crime.

Earlier studies linking lead to such problems used indirect measures of both

lead and criminality, and critics have argued that socioeconomic and other

factors may be responsible for the observed effects.

But by measuring blood levels of lead before birth and during the first

seven years of life, then correlating the levels with arrest records and brain

size, Cincinnati researchers have produced the strongest evidence yet that lead

plays a major role in crime.

The researchers also found that lead exposure is a continuing problem

despite the efforts of the federal government and cities to minimize exposure.

The average lead levels in the study " unfortunately are still seen in many

thousands of children throughout the United States, " said Philip J. Landrigan,

director of the Center for Children's Health and the Environment at the

Mount Sinai School of Medicine in New York.

The link between criminal behavior and lead exposure was found among even

the least-contaminated children in the study, who were exposed to amounts of

lead similar to what the average U.S. child is exposed to today, said

Landrigan, who was not involved in the study.

" People will sometimes say, 'This is in the past. We are cleaning up lead.

We don't have lead problems anymore,' " said criminologist Deborah W. Denno of

Fordham University in New York, who also was not involved in the study. " The

Ohio study says this is still a big problem. "

Nationwide, about 310,000 children between the ages of 1 and 5 have blood

lead levels above the federal guideline of 10 micrograms per deciliter, and

experts suspect that many times that number have lower levels that are still

dangerous.

" It is a national disgrace that so many children continue to be exposed at

levels known to be neurotoxic, " said neurologist C. Bellinger of Harvard

Medical School, who wrote an _editorial accompanying the study_

(http://medicine.plosjournals.org/perlserv/?request=get-document & doi=10.1371/jou\

rnal.pmed.0

050115) published in the online journal PLoS Medicine.

Although some urban soil is still contaminated with lead from gasoline, 80%

of lead exposure now comes from houses built before 1978. Paint in such

houses can contain as much as 50% lead, and even if it has been covered by

newer,

lead-free paint, it still flakes or rubs off.

About 38 million U.S. homes, 40% of the nation's housing, still contain

lead-based paint, according to the U.S. Department of Housing and Urban

Development. The problem is particularly acute in urban areas, which typically

have

older housing that has not been renovated.

More recently, parents and authorities have become concerned about

increasing levels of lead-based paint in toys imported from China.

Researchers have long known that lead exposure reduces IQ by damaging brain

cells in children during their early years.

It is also known that lead increases children's distractibility,

impulsiveness and restlessness and shortens their attention span, all factors

considered

precursors of aggressive or violent behavior.

A landmark 1990 paper by Denno linked lead to increases in criminal

behavior, but the children in the study were not tested for lead levels. The

diagnoses were based on their physicians' evaluation, Denno said.

The Cincinnati lead study enrolled 376 pregnant women in Cincinnati's inner

city between 1979 and 1984, measuring their blood lead levels during

pregnancy and the children's levels during their first seven years of life.

In the _new study_

(http://medicine.plosjournals.org/perlserv/?request=get-document & doi=10.1371/jou\

rnal.pmed.0050101) , environmental health researcher

Kim N. Dietrich of the University of Cincinnati College of Medicine studied 250

of the original group, correlating their lead levels with adult criminal

arrest records from Hamilton County, Ohio.

He and his colleagues found that 55% of the subjects (63% of males) had been

arrested and that the average was five arrests between the ages of 18 and 24.

The higher the blood lead level at any time in childhood, the greater the

likelihood of arrests. " The strongest association was with violent criminal

activity -- murder, rape, domestic violence, assault, robbery and possession of

weapons, " Dietrich said.

Blood lead levels in the children ranged from 4 to 37 micrograms per

deciliter.

The researchers found, for example, that every 5-microgram-per-deciliter

increase in blood lead levels at age 6 was accompanied by a 50% increase in the

incidence of violent crime later in life. Confirming previous findings, the

effect of lead was strongest in males, who had an arrest rate 4 1/2 times that

of females.

In a _related study_

(http://medicine.plosjournals.org/perlserv/?request=get-document & doi=10.1371/jou\

rnal.pmed.0050112) , spectroscopist Kim M. Cecil of

Cincinnati Children's Hospital Medical Center and her colleagues examined a

" representative sample " of 157 members of the same group using whole-brain MRI

scans. They found that those with the highest blood levels of lead during

childhood had the smallest brain volume.

On average, the brains of those in the study were about 1.2% smaller than

normal. The most affected regions of the brain were those regulating decision

making, impulse control, attention, error detection, task completion and

reward-based decision making.

" The most important message is that lead affects brain volume, independent

of demographic and social factors that are often used to explain away poor outc

omes " in life, Cecil said. " This is independent biological evidence showing

that the brain is affected by lead. "

_thomas.maugh@..._ (mailto:thomas.maugh@...)

_marla.cone@..._ (mailto:marla.cone@...)

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