Lead Exposure and Crime – a series of articles
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 Thomas H. Maugh II and Marla Cone
Los Angeles Times
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 David C. Bellinger of Harvard
Medical School, who wrote an editorial accompanying the study 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, 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, 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
outcomes" in life, Cecil said. "This is independent biological evidence showing
that the brain is affected by lead."
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Childhood lead exposure linked to adult crime
By Greg Toppo, USA TODAY
May 27, 2008
http://www.usatoday.com/news/health/2008-05-27-lead-levels-crime_N.htm
In what may be the strongest link yet between lead exposure and crime rates, researchers at the University of Cincinnati on Tuesday released new evidence, spanning more than 20 years, that draws a direct relationship between the amount of lead in a child's blood and the likelihood he or she will commit crimes as an adult.
Research has shown before that lead has harmful effects on judgment, cognitive function and the ability to regulate behavior. But until now the best research focused on juveniles, not adults.
Now, researchers have collected data from as early as 1979 when pregnant women and their healthy babies had their blood drawn regularly at four Cincinnati medical clinics. By the time the children were 7, researchers had a complete portrait of lead levels.
Nearly two decades later, the researchers tracked down 250 of the subjects, ages 19-24. Controlling for a host of factors, including parental IQ, education, income and drug use, the team found that the more lead in a child's blood from birth through age 7, the more likely he or she was to be arrested as an adult. The tie between high lead levels and violent crime was particularly strong.
"We need to be thinking about lead as a drug and a fairly strong one," says Kim Dietrich, a professor of environmental health at the University of Cincinnati College of Medicine and the principal investigator for the study in the journal Public Library of Science Medicine. "These kids have been exposed to this drug, chronically, since before birth."
For nearly 50 years, researchers have known about the relationship between children's impulsivity and high levels of lead in their bodies. As recently as 2007, economist Rick Nevin tied violent crime rates to historic use of leaded gasoline.
Children in poor neighborhoods are often exposed to high levels of lead from old lead paint in dilapidated homes.
Fordham University School of Law criminologist Deborah Denno, who has studied the effects of lead, calls the findings' ties to adult criminal behavior "very important." Denno studied National Institutes of Health statistics of nearly 1,000 children in Philadelphia and found that a high blood lead level at 7 years old was among the strongest predictors that a child would have both learning difficulties and disciplinary problems in school. High blood lead also strongly predicted whether a child would have a juvenile or adult criminal record.
Denno says Tuesday's data are newer than hers by 20 years. "It's still a huge problem," she says, "and it's still a huge problem among African-American communities and poorer neighborhoods."
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Research Links Lead Exposure, Criminal Activity
Data May Undermine Giuliani's Claims
By Shankar
Vedantam
Washington Post
Sunday, July 8, 2007; A02
http://www.washingtonpost.com/wp-dyn/content/article/2007/07/07/AR2007070701073.html
Rudy Giuliani never misses an opportunity to remind people about his track record in fighting crime as mayor of New York City from 1994 to 2001.
"I began with the city that was the crime capital of America," Giuliani, now a candidate for president, recently told Fox's Chris Wallace. "When I left, it was the safest large city in America. I reduced homicides by 67 percent. I reduced overall crime by 57 percent."
Although crime did fall dramatically in New York during Giuliani's tenure, a broad range of scientific research has emerged in recent years to show that the mayor deserves only a fraction of the credit that he claims. The most compelling information has come from an economist in Fairfax who has argued in a series of little-noticed papers that the "New York miracle" was caused by local and federal efforts decades earlier to reduce lead poisoning.
The theory offered by the economist, Rick Nevin, is that lead poisoning accounts for much of the variation in violent crime in the United States. It offers a unifying new neurochemical theory for fluctuations in the crime rate, and it is based on studies linking children's exposure to lead with violent behavior later in their lives.
What makes Nevin's work persuasive is that he has shown an identical, decades-long association between lead poisoning and crime rates in nine countries.
"It is stunning how strong the association is," Nevin said in an interview. "Sixty-five to ninety percent or more of the substantial variation in violent crime in all these countries was explained by lead."
Through much of the 20th century, lead in U.S. paint and gasoline fumes poisoned toddlers as they put contaminated hands in their mouths. The consequences on crime, Nevin found, occurred when poisoning victims became adolescents. Nevin does not say that lead is the only factor behind crime, but he says it is the biggest factor.
Giuliani's presidential campaign declined to address Nevin's contention that the mayor merely was at the right place at the right time. But William Bratton, who served as Giuliani's police commissioner and who initiated many of the policing techniques credited with reducing the crime rate, dismissed Nevin's theory as absurd. Bratton and Giuliani instituted harsh measures against quality-of-life offenses, based on the "broken windows" theory of addressing minor offenses to head off more serious crimes.
Many other theories have emerged to try to explain the crime decline. In the 2005 book "Freakonomics," Steven D. Levitt and Stephen J. Dubner said the legalization of abortion in 1973 had eliminated "unwanted babies" who would have become violent criminals. Other experts credited lengthy prison terms for violent offenders, or demographic changes, socioeconomic factors, and the fall of drug epidemics. New theories have emerged as crime rates have inched up in recent years.
Most of the theories have been long on intuition and short on evidence. Nevin says his data not only explain the decline in crime in the 1990s, but the rise in crime in the 1980s and other fluctuations going back a century. His data from multiple countries, which have different abortion rates, police strategies, demographics and economic conditions, indicate that lead is the only explanation that can account for international trends.
Because the countries phased out lead at different points, they provide a rigorous test: In each instance, the violent crime rate tracks lead poisoning levels two decades earlier.
"It is startling how much mileage has been given to the theory that abortion in the early 1970s was responsible for the decline in crime" in the 1990s, Nevin said. "But they legalized abortion in Britain, and the violent crime in Britain soared in the 1990s. The difference is our gasoline lead levels peaked in the early '70s and started falling in the late '70s, and fell very sharply through the early 1980s and was virtually eliminated by 1986 or '87.
"In Britain and most of Europe, they did not have meaningful constraints [on leaded gasoline] until the mid-1980s and even early 1990s," he said. "This is the reason you are seeing the crime rate soar in Mexico and Latin America, but [it] has fallen in the United States."
Lead levels plummeted in New York in the early 1970s, driven by federal policies to eliminate lead from gasoline and local policies to reduce lead emissions from municipal incinerators. Between 1970 and 1974, the number of New York children heavily poisoned by lead fell by more than 80 percent, according to data from the New York City Department of Health.
Lead levels in New York have continued to fall. One analysis in the late 1990s found that children in New York had lower lead exposure than children in many other big U.S. cities, possibly because of a 1960 policy to replace old windows. That policy, meant to reduce deaths from falls, had an unforeseen benefit -- old windows are a source of lead poisoning, said Dave Jacobs of the National Center for Healthy Housing, an advocacy group that is publicizing Nevin's work. Nevin's research was not funded by the group.
The later drop in violent crime was dramatic. In 1990, 31 New Yorkers out of every 100,000 were murdered. In 2004, the rate was 7 per 100,000 -- lower than in most big cities. The lead theory also may explain why crime fell broadly across the United States in the 1990s, not just in New York.
The centerpiece of Nevin's research is an analysis of crime rates and lead poisoning levels across a century. The United States has had two spikes of lead poisoning: one at the turn of the 20th century, linked to lead in household paint, and one after World War II, when the use of leaded gasoline increased sharply. Both times, the violent crime rate went up and down in concert, with the violent crime peaks coming two decades after the lead poisoning peaks.
Other evidence has accumulated in recent years that lead is a neurotoxin that causes impulsivity and aggression, but these studies have also drawn little attention. In 2001, sociologist Paul B. Stretesky and criminologist Michael Lynch showed that U.S. counties with high lead levels had four times the murder rate of counties with low lead levels, after controlling for multiple environmental and socioeconomic factors.
In 2002, Herbert Needleman, a psychiatrist at the University of Pittsburgh, compared lead levels of 194 adolescents arrested in Pittsburgh with lead levels of 146 high school adolescents: The arrested youths had lead levels that were four times higher.
"Impulsivity means you ignore the consequences of what you do," said Needleman, one of the country's foremost experts on lead poisoning, explaining why Nevin's theory is plausible. Lead decreases the ability to tell yourself, "If I do this, I will go to jail."
Nevin's work has been published mainly in the peer-reviewed journal Environmental Research. Within the field of neurotoxicology, Nevin's findings are unsurprising, said Ellen Silbergeld, professor of environmental health sciences at Johns Hopkins University and the editor of Environmental Research.
"There is a strong literature on lead and sociopathic behavior among adolescents and young adults with a previous history of lead exposure," she said.
Two new studies by criminologists Richard Rosenfeld and Steven F. Messner have looked at Giuliani's policing policies. They found that the mayor's zero-tolerance approach to crime was responsible for 10 percent, maybe 20 percent, at most, of the decline in violent crime in New York City.
Nevin acknowledges that crime rates are rising in some parts of the United States after years of decline, but he points out that crime is falling in other places and is still low overall by historical measures. Also, the biggest reductions in lead poisoning took place by the mid-1980s, which may explain why reductions in crime might have tapered off by 2005. Lastly, he argues that older, recidivist offenders -- who were exposed to lead as toddlers three or four decades ago -- are increasingly accounting for much of the violent crime.
Nevin's finding may even account for phenomena he did not set out to address. His theory addresses why rates of violent crime among black adolescents from inner-city neighborhoods have declined faster than the overall crime rate -- lead amelioration programs had the biggest impact on the urban poor. Children in inner-city neighborhoods were the ones most likely to be poisoned by lead, because they were more likely to live in substandard housing that had lead paint and because public housing projects were often situated near highways.
Chicago's Robert Taylor Homes, for example, were built over the Dan Ryan Expressway, with 150,000 cars going by each day. Eighteen years after the project opened in 1962, one study found that its residents were 22 times more likely to be murderers than people living elsewhere in Chicago.
Nevin's finding implies a double tragedy for America's inner cities: Thousands of children in these neighborhoods were poisoned by lead in the first three quarters of the last century. Large numbers of them then became the targets, in the last quarter, of Giuliani-style law enforcement policies.
ScienceDaily (Feb. 26, 2005) — WASHINGTON, Feb. 18 – Exposure to lead may be one of the most significant causes of violent crime in young people, according to one of the nation's leading researchers on the subject.
"When environmental lead finds its way into the developing brain, it disturbs neural mechanisms responsible for regulation of impulse. That can lead to antisocial and criminal behavior," reported Herbert L. Needleman, M.D., professor of psychiatry and pediatrics at the University of Pittsburgh School of Medicine, at the 2005 American Association for the Advancement of Science (AAAS) Annual Meeting. "The government needs to do more to eliminate sources of lead in the environment."
According to the U.S. Environmental Protection Agency, humans can encounter lead through deteriorating paint and dust, air, drinking water, food and contaminated soil. Sources of lead are plentiful – until the 1970s lead was used in paint, gasoline and older water pipes. Today, much of that lead is still out there – on old window frames, in the soil of the vegetable gardens and in the drinking water of many American cities.
In the 1970s, Dr. Needleman was the first to discover cognitive effects in children who had been exposed to lead. Though the children had no visible signs of lead poisoning, they had significantly lower scores on IQ tests. As a result of these studies and others, lead has been removed from gasoline, paint and numerous other products.
Such measures have resulted in sharply lower levels of lead in children born today, compared to those born 30 years ago. Yet, Dr. Needleman's latest research shows that even very low levels of lead found in bone, as measured by a technique called X-ray fluorescence, can affect brain development.
In a 1996 Pitt study of 301 children, those with the highest concentrations of lead – still below government-recommended safe levels – had tests scores showing more aggression, attentional disorders and delinquency. In 2002, those findings were extended to show that the average bone lead levels in 190 adjudicated delinquents was higher than normal controls. The results indicated that between 18 and 38 percent of all delinquency in Pennsylvania's Allegheny County, which includes Pittsburgh, could be due to lead. Additionally, a number of recent studies have shown a strong relationship between sales of leaded gasoline and rates of violent crime.
"The brain, particularly the frontal lobes, are important in the regulation of behavior," said Dr. Needleman. "Exposure to lead, at doses below those which bring children to medical attention, is associated with increased aggression, disturbed attention and delinquency. A meaningful strategy to reduce crime is to eliminate lead from the environment of children."