RACHEL'S ENVIRONMENT & HEALTH NEWS #797
August 5, 2004
TOXIC LEAD AND VIOLENCE
The poisoning of children by the toxic metal, lead, was first
reported in 1892. By 1904 the cause of the poisoning was
correctly identified as dust from lead-based paint, which was
flaking off the walls inside homes. Today, 100 years later,
lead-based paint flaking off the walls of old buildings is
still the main cause of childhood lead poisoning.
As early as 1897 -- 107 years ago -- the paint industry
acknowledged that its lead-based products were poisonous to
children. Today, after more than a century of poisoning
children, the paint industry continues to sell lead-based
paint, though its use inside homes was restricted in Australia
in 1920, in many European countries in 1923-24, and in the U.S.
belatedly in 1972.
5-Stage History of Childhood Lead Poisoning
The struggle to prevent the poisoning of children by toxic lead
has gone through 4 stages and has now entered a 5th stage.
During stage 1, which lasted from 1892 to about 1914, the
medical and public health communities simply refused to accept
the mounting evidence that lead could harm children.
During stage two (1914 to 1943), medical authorities
acknowledged that childhood lead poisoning was epidemic, but
they assumed (incorrectly) that it led to only two possible
outcomes: death or complete recovery.
During stage 3 (1944 to 1970), medical authorities acknowledged
that children who recovered from gross lead poisoning were
permanently affected: they had trouble thinking, concentrating
and learning; they performed poorly in school; and they were
prone to aggressive, violent behavior and explosive
tempers.[1,5,6] However, during this stage, it was assumed that
a child had to exhibit gross symptoms before permanent damage
could occur. Gross symptoms of lead poisoning includes
seizures, palsy, loss of control of the limbs, and impairment
of hearing and sight.
Also during this stage, starting in 1950, medical authorities
learned that lead was disproportionately harming
African-American and Hispanic children and children of the
poor. This remains true today, a central issue of environmental
justice. See Rachel's #294.
During stage 4 (1970 to 1994), medical authorities began to
recognize that children could be permanently poisoned by lead
even without showing gross symptoms such as seizures or palsy.
The breakthrough study was Herbert Needleman's 1979 report in
the New England Journal of Medicine, relating lead in
children's baby teeth to diminished mental capacity.
During this fourth stage, numerous studies focused narrowly on
loss of mental capacity, especially IQ, confirming that lead
permanently damages children's central nervous systems, even at
exposure levels that produce no gross symptoms.[9,10,11,12,13]
I reviewed many of these studies in Rachel's #529.
In response to these studies, between 1970 and 1991 the U.S.
government lowered the official "level of concern" for lead in
children's blood from 60 micrograms of lead per deciliter of
blood (mcg/deciliter) to 40 then to 30 then to 25 and finally
to 10. (A deciliter is 1/10th of a liter and a liter is
approximately a quart. There are 28 grams in an ounce and a
microgram is one millionth of a gram.)
Among medical authorities, the 10 mcg/deciliter "level of
concern" is now widely taken to represent a threshold, a level
below which lead is "safe." For example, the New Jersey
Department of Environmental Protection says children with 20
mcg/deciliter lead in their blood are "poisoned" and children
with more than 10 mcg/deciliter have "elevated" lead -- but
below 10 is considered to be of no consequence.
Unfortunately, there is now a solid body of medical evidence
showing that this assumption is dangerously false. At levels as
low as 1 to 3 mcg/deciliter, lead reduces children's IQ,
diminishes math and reading skills, and changes behavior for
the worse. [9,10,11,12,13] There is no known level of lead that
is safe for young children.
If we assume the level of concern should be 5 mcg/deciliter of
lead in blood (half the current "official" level of concern),
we can see that lead remains an enormous problem among U.S.
There are about 19 million children in the U.S. between the
ages of 1 and 5. Of these, 4.9 million (25.6%) have blood lead
levels of 5 mcg/deciliter or higher. Among African-American
children, 46.8% have 5 or more mcg/deciliter. Among Hispanic
children, 27.9% have 5 mcg/deciliter or higher. Among whites,
18.7% have 5 mcg/deciliter or higher. These data were published
in 2003, but they were gathered during the most recent
available survey, 1988-1994.[16,17]
How does the current allowable level of lead in blood compare
to natural background levels? The relationship between lead in
blood and led in bone is understood. Careful measurements of
the bones of preindustrial humans have revealed that the true
"natural background" level of lead in human blood is 0.016
mcg/deciliter. Therefore the U.S. government's current "level
of concern," 10 mcg/deciliter, is 625 times as high as the
natural background level.
The presence of a potent nerve poison in children at levels 625
times as high as normal (or even 300 times as high as normal)
should set off loud alarm bells, but the U.S. government
recently reaffirmed that it is keeping the "level of concern"
at 10 mcg/deciliter because, "[T]here is no evidence of a
threshold below which adverse effects are not experienced.
Thus, any decision to establish a new level of concern would be
arbitrary..." The Mad hatter himself could not top that
During Stage 4 of the history of lead, many studies showed that
children exposed to lead not only had learning problems but
also were distractible, disorganized, impulsive and restless --
the hallmarks of attention deficit disorder. In short, the
mechanism that regulates attention and self-control is damaged
by lead. It is now widely recognized that the symptoms of
attention deficit hyperactivity disorder (ADHD) are shared by
many children exposed to neurotoxicants such as PCBs
[polychlorinated biphenyls] and lead.[20,21,22]
In sum, during stage 4 scientists determined that lead, at
levels as low as 1 to 3 micrograms of lead in blood diminishes
a child's ability to think, concentrate, learn and achieve
Stage 5 of the struggle to protect children began around 1994
and is ongoing now. During this period, it is slowly dawning on
medical authorities that exposing children to toxic lead --
even at levels below 10 mcg per deciliter -- causes some of
them to become impulsive, aggressive, antisocial, delinquent
and violent. The more lead, the worse the behavior. Herbert L.
Needleman has recently suggested that this may turn out to be
the most important effect of exposing children to lead.
Violence in the U.S. is a huge problem. Despite a downward
trend in recent years, 1.4 million violent crimes were
committed during 2000, including 16,765 homicides, in addition
to 29,350 suicides.
In 1996 Herbert L. Needleman published a report in JAMA, the
Journal of the American Medical Association, revealing a strong
link between lead in children's bones and delinquent
behavior. Needleman's study was not the first to link lead
to antisocial tendencies, but it was one of the most
carefully done. Several studies since 1996 have confirmed what
Needleman's 1996 findings came as a surprise to many people,
but they should not have. As I mentioned earlier, in 1943
Randolph Byers and Elizabeth Lord studied 20 children that had
experienced mild lead poisoning during infancy. None of the 20
children had exhibited overt signs of lead poisoning, yet the
growth and development of their nervous systems had been
"seriously impaired." Among the 20 children examined, only one
had progressed satisfactorily in school. Furthermore, many of
the children were emotionally impaired as well. Byers and Lord
characterized the behavior of many of the children as
"unreliable impulsive behavior, cruel impulsive behavior, short
attention span, and the like." Three of the 20 children were
expelled from school, one for setting fires, another for
repeatedly getting up and dancing on the desks, and a third for
sticking a fork into another child's face.
In Rachel's #529 (Jan. 16, 1997) we had reported on the Byers
and Lord study and on several subsequent studies linking lead
exposure to violent and aggressive behavior. Throughout the
1980s studies continued to link lead to violence.
What is different now is the improved quality of the studies,
plus much better understanding of brain chemistry. In 2003, the
American Chemical Society published a report called "A Recipe
for Violence" which described current understanding of the
links between brain chemistry, toxic lead, alcohol, and
impulsive, unplanned violence.
One key is a chemical in the brain called serotonin (also known
as 5-HT), which acts as a brake on impulsiveness. Individuals
with normal levels of serotonin show restraint and think things
through before they act. They have the ability to foresee the
consequences of their actions. On the other hand, people with
low serotonin levels are liable to act first and think later,
which can get them into trouble.
Serotonin plays the same role in monkeys as it does in humans.
Researchers who have spent 25 years studying a colony of 5000
free-ranging rhesus monkeys on an island in South Carolina
report that monkeys with low serotonin levels end up with more
scars and wounds than monkeys with normal serotonin levels.
Human studies confirm the role of serotonin in violent
behavior. Among a group of arsonists, those who set fires
impulsively were the ones with low serotonin. A study of
prisoners who had committed impulsive, violent crimes revealed
that low serotonin levels were linked to more frequent
aggressive behavior and greater violence.
What's the connection to lead? Lead reduces serotonin levels.
The more lead present, the less serotonin. Lead may contribute
to aggressive and violent behavior in several ways. Exposure to
lead reduces serotonin and simultaneously reduces a child's
ability to succeed in school. This in turn leads to low
self-esteem, irritability and frustration. People with low
levels of serotonin cannot handle frustration as well as people
with normal serotonin. Furthermore, when alcohol is available,
rats and monkeys with low serotonin levels seek out alcohol
more than animals with normal serotonin levels. Alcohol then
makes the situation worse in several ways. First, alcohol
metabolizes serotonin, further lowering serotonin levels.
Simultaneously alcohol clouds an individual's judgment and
relaxes normal restraints on behavior. Among experimentally
intoxicated monkeys on the island in South Carolina, the only
ones who attack humans (six times their size) are those with
the lowest serotonin levels. Among humans, about half of all
violent crimes -- whether murders, rapes, or whatever --
No one believes lead is responsible for all aggressive,
violent, or delinquent behavior. Herbert L. Needleman believes
lead may explain somewhere between 10% and 40% of such
behaviors. Furthermore, no one is arguing that the
connection between lead and violence absolves individuals of
responsibility for their behavior. People are ultimately
responsible for their own actions, but no one can deny that the
physical and psychological environment during the formative
years can predispose an individual to aggressive and violent
Studies show that a tendency toward violence can be
counteracted by good parenting and sometimes by medical
interventions. Children who receive lots of love and nurturing
can overcome some of the mental and emotional handicaps created
by lead exposure. Some pharmaceutical products may help some
people with low serotonin levels (Prozac, Zoloft, lithium, and
others). Furthermore, parents who cope with the normal
irritations and frustrations of life without becoming violent
themselves-- for example, parents who control their own
impulsive anger -- can show children by example that violence
is not necessary or desirable.
Still, parents and children should not have to work to overcome
the artificial disadvantages created by exposure to lead. This
is a matter of simple justice. Lead poisoning is entirely
preventable, and numerous studies have shown that preventing it
would pay society enormous monetary benefits.
By examining the relationship between lifetime earnings and IQ,
and the relationship between IQ and lead in blood, researchers
have shown that the current average lead level in the nation's
3.8 million 5-year-olds (2.7 mcg/deciliter) will reduce their
cumulative lifetime earnings by $43.4 billion dollars. This
will be true of next year's 5-year-olds as well, so lead in
blood is costing us about $43 billion each year in lost
earnings alone (not to mention the lead-related costs of
medical care and violence).
In 2000, the federal government estimated that it costs $9000
to fully remediate an average lead-contaminated home and that
complete remediation of all pre-1960 housing would cost the
nation $16.6 billion per year for 10 years.[2, pg. 5] With
benefits of $43.3 billion each year, investing $16.6 billion
per year in lead abatement would provide the nation an enormous
gain (extending well beyond 10 years), and would serve our
national goal of "justice for all." Unfortunately, President
Bush has allocated only $139 million for lead abatement in 2005
-- 20% less than in 2004, and less than 1% of what's needed. At
the current rate of federal spending, the lead paint problem
will be with us for another 120 shameful years.
 Herbert Needleman, "Lead Poisoning," Annual Review of
Medicine Vol. 55 (2004), pgs. 209-222. Available at
 President's Task Force on Environmental Health Risks and
Safety Risks to Children, Eliminating Childhood Lead Poisoning;
a Federal Strategy Targeting Lead Paint Hazards (Washington,
D.C.: U.S. Environmental Protection Agency, Feb., 2000.)
Available at http://www.epa.gov/lead/fedstrategy2000.pdf and at
 See this advertisement from 1897 offering paint that "Is
NOT made with lead and is non poisonous":
 Sven Hernberg, "Lead Poisoning in Historical Perspective,"
American Journal of Industrial Medicine Vol. 38 (2000), pgs.
244-254. Available at
 David C. Bellinger, "Lead," Pediatrics Vol. 113, No. 4
(April 2004). Available at
 Randolph K. Byers and Elizabeth E. Lord, "Late Effects of
Lead Poisoning on Mental Development," American Journal of
Diseases of Children Vol. 66, No. 5 (November 1943), pgs.
471-494. Available at
 See Rachel's #294 at
Rachel's #687 at
Rachel's #688 at
Rachel's #689 at
 Herbert L. Needleman and others, "Deficits in Psychologic
and Classroom Performance of Children with Elevated Dentine
Lead Levels," New England Journal of Medicine Vol. 300, No. 13
(March 29, 1979), pgs. 689-693. Available at
 Theodore I. Lidsky and Jay S. Schneider, "Lead
neurotoxicity in children: basic mechanisms and clinical
correlates," Brain Vol. 126 (2003), pgs. 5-19. Available at
 Lisa M. Chiodo and others, "Neurodevelopmental effects of
postnatal lead exposure at very low levels," Neurotoxicology
and Teratology Vol. 26 (2004), pgs. 359-371. Available at
 Joel Schwartz, "Low-Level Lead Exposure and Children's IQ:
A Meta-Analysis and Search for a Threshold," Environmental
Research Vol. 65 (1994), pgs. 42-55. Available at
 Bruce P. Lanphear and others, "Cognitive Deficits
Associated with Blood Lead Concentrations Less Than 10
Micrograms per Deciliter in U.S. Children and Adolescents,"
Public Health Reports Vol. 115 (Nov.-Dec., 2000), pgs. 521-529.
Available at http://www.rachel.org/library/getfile.cfm?ID=446
 Richard L. Canfield and others, "Intellectual Impairment
in Children with Blood Lead Concentrations below 10 mcg per
Deciliter," New England Journal of Medicine Vol. 348, No. 16
(April 17, 2003), pgs. 1517-1526. Available at
 See Rachel's #529 at
 See pgs. 841-849 of Appendix 4 of the Final Report of the
New Jersey Comparative Risk Project (Trenton, N.J.: N.J.
Department of Environmental Protection, 2003) available at
 Susan M. Bernard, "Should the Center for Disease Control
and Prevention's Childhood Lead Poisoning Intervention Level Be
Lowered?" American Journal of Public Health Vol. 93, No. 8
(August 2003), pgs. 1253-1260. Available at
 Susan M. Bernard and Michael A. McGeehin, "Prevalence of
Blood Lead Levels >= 5 mcg/deciliter Among U.S. Children 1 to 5
Years of Age...," Pediatrics Vol. 112, No. 6 (December 2003),
pgs. 1308-1313. Available at
 A. Russell Flegal and Donald R. Smith, "Lead Levels in
Preindustrial Humans," New England Journal of Medicine Vol.
326, No. 19 (May 7, 1992), pgs. 1293-1294. Available at
 Centers for Disease Control and Prevention, "Why not
change the blood lead level of concern at this time?" Available
accessed August 5, 2004; also available at
 Deborah C. Rice, "Parallels between Attention Deficit
Hyperactivity Disorder and Behavioral Deficits Produced by
Neurotoxic Exposure in Monkeys," Environmental Health
Perspectives [Supplement 3] Vol. 108, No. S3 (June 2000), pgs.
405-408. Available at
 Alan L. Mendelsohn and others, "Low-level Lead Exposure
and Behavior in Early Childhood," Pediatrics Vol. 101, No. 3
(March 1998), pg. E10. Available at
 William G. Sciarillo and others, "Lead Exposure and Child
Behavior," American Journal of Public Health Vol. 82, No. 10
(October 1992), pgs. 1356-1360. Available at
 Sophie L. Wilkinson, "A Recipe for Violence," Chemical &
Engineering News Vol. 81, No. 22 (June 2, 2003), pgs. 33-37.
Available at http://www.rachel.org/library/getfile.cfm?ID=462
 Herbert L. Needleman and others, "Bone Lead Levels and
Delinquent Behavior," JAMA Vol. 275, No. 5 (Feb. 7, 1996), pgs.
363-369. Available at
 David Bellinger and others, "Pre- and Postnatal Lead
exposure and Behavior Problems in School-Aged Children,"
Environmental Research Vol. 66 (1994), pgs. 12-30. Available at
 Herbert L. Needleman and others, "Bone lead levels in
adjudicated delinquents; a case control study," Neurotoxicology
and Teratology Vol. 24 (2002), pgs. 711-717. Available at
 Paul B. Stretsky and Michael J. Lynch, "The Relationship
between Lead Exposure and Homicide," Archives of Pediatric and
Adolescent Medicine Vol. 155 (May, 2001), pgs. 579-582.
Available at http://www.rachel.org/library/getfile.cfm?ID=439
 Kim N. Dietrich and others, "Early exposure to lead and
juvenile delinquency," Neurotoxicology and Teratology Vol. 23
(2001), pgs. 511-518. Available at
 Deborah W. Denno, Biology and Violence (New York:
Cambridge University Press, 1990); ISBN 0521362199. I have not
seen this book. Denno reportedly followed 987 African-Americans
from birth to age 22 years, finding that among the dozens of
factors that correlated with delinquency, lead exposure was
among the strongest for males.
 See Rachel's #529 at
http://www.rachel.org/bulletin/index.cfm?issue_ID=594 and the
PDF version at
 Philip J. Landrigan and others, "Environmental Pollutants
and Disease in America's Children: Estimates of Morbidity,
Mortality, and Costs of Lead Poisoning, Asthma, Cancer, and
Developmental Disabilities," Environmental Health Perspectives
Vol. 110, No. 7 (July 2002), pgs. 721-728. Available at
 Avram Goldstein, "Bush Budget Would Cut Lead Funds; Poison
Prevention is Program's Aim," Washington Post April 11, 2004.
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