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or years, mothers have been telling pediatricians that their children changed after being exposed to toxic lead, says Herbert Needleman, a professor of child and pediatrics at the University of . These mothers saw that their children became more fidgety, less compliant, and more aggressive. If frustrated, the children often became violent. Science has since proven what moms first observed—lead is now known to be associated with cognitive impairment, learning disabilities, and behaviors that contribute to the likelihood of drop- ping out of high school. Today, some environmental researchers are taking an even harder look at lead and are advancing the notion that widespread exposure of children to toxicants such as lead may have helped spark the crime waves that rocked the throughout the twentieth century. “Maybe the more important outcome from lead expo- sure is not cognition or psychometric intelligence; it’s that it interferes with social adjustment or your ability to control your impulses and plan ahead,” says Needleman. Moreover, these scientists posit, further reducing contin- uing exposures in the womb and during infancy and early childhood may prevent future crime.

Environmental Health Perspectives • VOLUME 110 || NUMBER 10 || October 2002 A 575 Focus • The Lead Effect?

Needleman has long been at the fore- nile delinquency among 195 inner-city in both cognitive and behavioral function, front of the debate over a possible relation- youth in Cincinnati. Blood lead levels were including aggressiveness, impulsiveness, and ship between childhood lead exposure and sampled before birth and through adoles- ability to pay attention,” says Ted Schettler, the development of juvenile delinquency and cence. Published in the November/ science director of the Science and a propensity to commit criminal acts. December 2001 issue of Neurotoxicology and Environmental Health Network, an envi- Evidence that induces severe Teratology, it’s the first long-term study to ronmental and public health policy think behavioral problems has been around for track lead exposure in children from womb tank. “Whether they translate into crime is decades. Today, however, Needleman and to mid-adolescence. another matter.” A History of Prior Bad Acts Today, the chief source of lead exposure for Adolescent boys with American children is through ingestion or inhalation of deteriorating lead paint in elevated lead levels older housing. Use of lead in house paint peaked in 1914 and was banned in 1978. were more likely to engage According to the Department of Housing and Urban Development (HUD), lead in acts of bullying, vandalism, paint coats surfaces in 39 million homes, or 40% of the nation’s entire housing stock. arson, shoplifting, and HUD estimates that, of those homes, lead paint hazards lurk in about 25 million, other delinquent behaviors. more than one-fifth of which are currently occupied by a child under the age of 6. Lead was first introduced to gasoline in the mid-1920s, after a General Motors sci- –Needleman study entist discovered its octane-boosting effects. Journal of the American Medical Association Tetraethyl lead may have been an inexpen- sive octane enhancer, but it also proved a particularly pernicious pollutant because of other researchers are building a stronger case “There appears to be a linear relation- its neurodevelopmental effects and its indef- for behavioral effects at relatively low levels ship between blood lead levels and the inite persistence in the environment. of exposure. The past decade has produced a number of reported delinquent acts from Before its phaseout under the Clean Air series of intriguing findings. the lowest levels of exposure to the highest,” Act beginning in the late 1970s, lead in A study of some 300 Pittsburgh stu- Dietrich says. Interestingly, the team found gasoline was the greatest source of exposure; dents, led by Needleman and published in no gender difference in the correlation. indeed, leaded gas made the toxicant essen- the 7 February 1996 issue of the Journal of Exposed girls were as likely as boys to com- tially ubiquitous in the environment. In the American Medical Association, first mit delinquent acts, despite the fact that 1976, nearly 90% of U.S. children aged revealed that adolescent boys with elevated male gender is almost always a risk factor for 1–5 had blood lead levels exceeding the 10 lead levels were more likely to engage in acts engagement in delinquent behavior. µg/dL guideline set by the Centers for of bullying, vandalism, arson, shoplifting, Intriguing as these findings are, there is Disease Control and Prevention (CDC). and other delinquent behaviors, according to still skepticism over whether lead exposure After lead’s phaseout from gasoline, the self and parental reports. really contributes to delinquency. “There’s mean concentration dropped across all In their latest work, presented at the no disagreement that lead can cause changes demographic groups in the entire popula- 2000 joint conference of the American Academy of Pediatrics and Pediatric Academic Societies in , Needleman’s team used X-ray fluorescence technology to examine bone lead concentrations in rough- Variations in leaded gasoline ly 350 youngsters aged 12–18 in Allegheny County, Pennsylvania, to gauge past expo- sales from 1941 to 1986 sures. The team found significantly higher bone lead levels in children convicted of correlate with roughly delinquency than in those with no juvenile convictions. Among boys, convicted delin- 90% of the fluctuations quents were almost twice as likely to have higher bone lead concentrations, in violent crime rate Needleman reports, and four times as likely after adjusting for confounding factors. from 1960 to 1998. Last year, Kim Dietrich, a developmental psychologist and professor of environmental health and pediatrics at the University of –Nevin study Cincinnati College of Medicine, reported a Environmental Research significant link between prenatal and other early exposures to lead and self-reported juve-

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tion uniformly from 16 µg/dL in 1976 to 2 much of the variance is attributable to University of Rochester, “The effect of lead µg/dL by 1999. By 1990, 90% of U.S. chil- genetics and how much to environment. is much greater on kids from lower-income dren aged 1–5 met the CDC guidelines, “Lead’s links with aggression, impulsive families. If you’re dealing with a disadvan- according to data from the National Health behavior, and attention loss are pretty clear, taged population that already has a lower and Nutrition Examination Survey. and that sets a kid up to have problems in mean IQ and you expose that population Even levels below the 10 µg/dL CDC school,” Schettler explains. Although such to a neurotoxicant, especially a develop- threshold are reported to still have health effects themselves add to the risk of running mental neurotoxicant, you will find the effects, including lowering IQ and causing into trouble with the law, struggling stu- effect amplified, which means you have to behavioral problems. A team led by Bruce dents tend to drop out or not pursue higher think about effect modification.” Lanphear at Children’s Hospital Medical education, making it tougher to land high- In many ways, says Weiss, by stripping Center in Cincinnati reported at the 2000 paying or interesting jobs, he says. “And you away confounding factors, what science joint conference of the American Academy start putting that together with all the other has done is to focus too intensely on one of Pediatrics and Pediatric Academic social factors, and it’s very possible there’s a set of risks when there are multiple risks Societies that cognitive defects in reading, link with delinquent behavior and crime at whose interactions might provoke even math, short-term memory, and visual con- some point that’s very plausible,” Schettler greater adverse effects. “It’s not just certain struction skills occur at levels as low as 2.5 says. “Who knows whether there are two, disadvantaged populations that suffer µg/dL. three, or more steps in that cascade.” higher exposures to lead, because we know Developmental exposures to lead, Philip Landrigan, chair of community that minority kids have higher levels,” he depending on the time and level of the and preventive medicine at Mount Sinai says. “But in general, because of their social exposure, have exhibited a variety of effects School of Medicine, points out that just and economic circumstances, they also are on the brain on a mechanistic level, includ- because a child is exposed to lead doesn’t exposed to other kinds of risks that might ing detectable structural changes. But researchers have yet to pin There’s no disagreement that lead down a direct mechanism that can cause changes in both might contribute to the development cognitive and behavioral function, of delinquent behavior. “Lead including aggressiveness, impulsiveness, does so much dam- age, it’s hard to and ability to pay attention. . . . decide what is the important factor,” Whether they translate into crime N eedleman explains. Plus, neu- is another matter. rologists still don’t understand the neurophysiological –Ted Schettler basis for delinquent Science and Environmental Health Network behavior of any type. Some behav- iorists have suggested that lead’s adverse guarantee that the child will end up going add to or multiply the kinds of risks that effects on parts of the brain that control to jail or being a criminal, although it may are posed by lead exposure or other kinds behaviors such as aggressiveness may be a increase the risk. “That injury which is done of toxicant exposure.” possible route. For example, lead’s ability to to the brain of a child early in life by lead In such debates, proving a direct link impair function of the prefrontal lobe, sets the stage for the child possibly becom- remains a challenge. “The easiest part is where impulsivity is regulated, may be a fac- ing delinquent or criminal when the child identifying association; it’s most difficult tor, Needleman says. gets older,” he says. “But whether the child going from association to a pure cause-and- actually goes on to become delinquent or effect relationship,” acknowledges Bailus Nature, Nurture, or Both? criminal depends on other factors as well. It Walker, a professor of environmental and Scientists agree that lead exposure is associ- depends upon the family structure, the occupational medicine at Howard ated with decreased IQ. The general con- school, the community, the whole psycho- University School of Medicine. Frequently, sensus is that for every increase in blood lead logical environment in which the child however, the standard of proof is politicized. of 4 µg/dL, there is a 1-point drop in IQ. grows up.” Studies that might prove an effect have Although there’s a long history in the psy- In fact, many researchers believe the never been done, or the bar is set so high by chological literature of studies documenting impacts of lead on criminal behavior work skeptics that a link will never be demon- relationships between IQ and criminality, synergistically not only with other social strated. Yet Walker admits, “Our current debate still rages over whether it is lead’s risk factors but with other detrimental epidemiological tools may not be sharp effects on IQ or its effects on psychosocial effects of lead exposure, such as impaired enough to advance our understanding there. function that are the more important factors learning abilities. For example, says Perhaps if we went to the molecular level, contributing to delinquency. What’s espe- Bernard Weiss, a professor of environmen- that might help us really understand this

KPT cially controversial is the question of how tal medicine and pediatrics at the issue much better.”

Environmental Health Perspectives • VOLUME 110 | NUMBER 10 | October 2002 A 577 Focus • The Lead Effect?

Researchers can currently only speculate delinquent, which is a risk factor for delin- rate variations between 1900 and 1960, pos- on mediating neurobehavioral factors such quency. “Parent variables are crucial in their sibly explaining about 70% of the change, as academic skills and self-regulatory ability, association with later behavioral problems,” the study found. A lag effect of 18–23 which are also under examination. To test Kaufman says. “[The studies] left uncon- years—basically the time it takes an exposed theories on how lead’s disruption of brain trolled what potentially is the most impor- child to grow up—was documented, pathways and mechanisms contributes to tant variable.” Although Kaufman believes depending on the specific crime. antisocial behavior, studies using magnetic “this is a totally fruitful topic to be “I’m absolutely convinced the incredibly resonance imaging and magnetic resonance researched,” he asserts that “much has been sharp decline in violent crime we’ve seen all spectroscopy are under way to identify made over little evidence. More credence across the country since 1990 is a reflection regions of abnormal brain functioning in needs to be given to the parents’ role.” of the sharp decline in childhood lead expo- members of Dietrich’s Cincinnati cohort. But Dietrich and Needleman maintain sure that began in the early 1970s and accel- According to one such theory, set forth in that the recent studies do use controls for erated after 1980,” says Nevin. “It just starts the 1995 World Health Organization report myriad confounding factors, including to become undeniable that there’s a very Environmental Health Criteria 165: parental intelligence, the quality of caregiving strong relationship. . . . It is so horrifying Inorganic Lead, early exposure to lead may throughout infancy and early childhood, and that childhood lead exposure could explain lower levels of serotonin and enhance socioeconomic status, among others. “The that much of the variation in violent crime.” dopamine sensitivity. Such neurotransmit- majority of the parents of the teens in my Nevin’s continuing work is finding a sim- ters are involved in mediating responses to study grew up in the same lead-contaminat- ilar association between trends in violent external stimuli. ed housing as their offspring,” Dietrich says. crime and leaded gas sales in a dozen other Some researchers have raised concerns “Lead undoubtedly played an adverse role in industrialized countries. A more refined about the limitations of X-ray bone spec- [the parents’] neurodevelopment as well.” analysis of the available data on lead exposure from paint may explain variations in murder rates in America’s The fact that a child is exposed largest cities during the period 1979–1991, to lead in no way guarantees when the U.S. murder rate hit its peak. that the child is going to end up However, the con- sensus of the research in jail or being a criminal. community is that, although Nevin’s work But it does increase the risk, is interesting and invites further study, it and then social circumstances are isn’t nearly as solid sci- entifically as the case–control studies of important modifying factors. Dietrich, Needleman, and others. In addition, –Philip Landrigan although Nevin Mount Sinai School of Medicine attempted to factor in everything from unem- ployment trends to teen troscopy, used in many of the studies, given Ecologic Evidence birth rates, controlling for important vari- its status as an experimental technique. Meanwhile, ecologists and social theorists ables at the national, regional, and local levels “We’re not at a point where we can take a are adding fuel to the fire. In a recent exam- over decades is no easy task. bone lead concentration measurement and ination of data from the 1900s, researchers But additional environmental evidence say what [the subject’s] blood lead level his- found a correlation between the amount of is being tabulated. A study published in the tory was over time,” Dietrich explains. But lead released into the environment from May 2001 issue of the Archives of Pediatrics in many circles, X-ray bone spectroscopy is auto exhaust and paint, and violent crime, and Adolescent Medicine found a link gaining ground on the blood lead level test as including rape, robbery, assault, and murder. between high concentrations of lead in the the standard for assessing exposure. It offers The study was published in the May 2000 air and higher homicide rates. Sociologist the best potential for getting a retrospective issue of Environmental Research, and was Paul Stretesky of Colorado State University picture of exposures, Dietrich says, because conducted by Rick Nevin, vice president of in Fort Collins and criminologist Michael lead only stays in the bloodstream for a ICF Consulting (a housing and environ- Lynch of the University of South Florida in month or two after an exposure, but is mental health issues firm in Fairfax, Tampa examined 1990 U.S. Environmental deposited in bone, where it remains for Virginia) under contract to HUD. Protection Agency data from 3,111 counties decades. According to the study, variations in in the United States and found that the Alan S. Kaufman, a clinical professor of leaded gasoline sales from 1941 to 1986 cor- counties with the highest air lead concentra- psychology at Yale University School of relate with roughly 90% of the fluctuations tions had homicide rates nearly four times Medicine, contends that existing studies in violent crime rates from 1960 to 1998. higher than counties with the lowest levels, neglected to control for generational rela- Variations in predicted childhood lead expo- after adjusting for 15 confounding variables. tionships of social dysfunction, such as sure from the use of lead paint between 1879 When the agency releases the next round of

whether a child’s parents were themselves and 1940 strongly correlate with murder air data, for 2000, the scientists will take KPT

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another look to see how the same coun- ties are doing. There still are pockets in under- “As far as crime policies go, it may be resourced communities, typically important to clean up lead in some parts minority and low-income communities, of the environment, in certain areas in where lead exposure continues to be certain parts of cities, to help to reduce crime,” Stretesky a problem. . . . These at-risk populations says. “I’m convinced that Needleman was usually aren’t a powerful political force, on to something when he started look- so they are often overlooked ing at this.” Jessica Wolpaw by policy makers. Reyes, a researcher at –Bailus Walker Harvard University’s Howard University School of Medicine National Bureau of Economic Research, predicts that the total removal of lead from Roughly 890,000 youngsters aged 1–5 are fied with symptoms to take any action, and gasoline under the Clean Air Act may estimated to still have blood lead levels at or even then the action is half-hearted, ineffec- eventually cause a nearly 30% drop in vio- above 10 µg/dL, though new estimates are tive, and of course too late.” lent crime between 1993 and 2013. Her expected from the CDC this fall. African- Chelation therapy is currently the stan- work also corroborates the strong correla- American children are five times as likely as dard treatment for lead poisoning. The tion between the removal of lead from Caucasian children to be overexposed. treatment uses a chemical such as succimer gasoline in the 1970s and reduction in “There still are pockets in under- that binds lead in the blood so it may then crime in the 1990s. Wolpaw Reyes bases resourced communities, typically minority be excreted. Although chelation therapy her estimate on an analysis of state-by-state and low-income communities, where lead removes lead from the blood, a study led by crime and lead exposure data from the past exposure continues to be a problem,” NIEHS epidemiologist Water Rogan and century. Her work, presented in her June Walker says. “These at-risk populations usu- published in the 10 May 2001 issue of the 2002 Harvard dissertation, awaits peer ally aren’t a powerful political force, so they New England Journal of Medicine reveals review and publication. are often overlooked by policy makers.” that cognitive loss is not restored. “We’re still not adequately screening the The costs continue to pile up. In a The Power—and Price—of population so that we’re picking up all of study in the July 2002 issue of Prevention the kids that are lead-exposed,” Schettler Environmental Health Perspectives, a team Despite successes in lead abatement, much says. Furthermore, says Don Ryan, execu- led by Landrigan estimates the total annu- work remains. Tragically, hundreds of thou- tive director of the Alliance to End al health care costs of lead poisoning: a sands of children continue to be exposed at Childhood Lead Poisoning, an advocacy staggering $43.4 billion a year, or about substantial levels in the United States. group, “We wait until children are identi- 2.2% of total U.S. health care costs. The costs include direct treatment costs and also such collateral damage as special education HUD’s current program, and reduced lifetime learning capacity. “It’s a national scan- dal,” Landrigan says. which provides $115 million in grants Many advocates are look- ing to the lead paint industry to remove leaded paint entirely to bear some of the burden, regardless of whether the or at least contain it companies knew the extent of the hazard at the time the or stop its deterioration, is paint was applied. “That’s the big question we as a country enough to remediate less than 0.1% have to answer: What is the proper role of the lead paint of seriously dangerous houses. manufacturers in the equa- tion?” Ryan says. –Don Ryan This fall a jury in the Alliance to End Childhood Lead Poisoning Rhode Island Superior Court will hear a case brought by Rhode Island attorney general

Environmental Health Perspectives • VOLUME 110 | NUMBER 10 | October 2002 A 579 Focus • The Lead Effect?

Sheldon Whitehouse against nine manufac- turers of lead paint and their industry asso- ciation, alleging that the presence of lead The total annual costs paint in buildings constitutes a public nui- sance. The case could lead to millions in of lead poisoning damages. Similar cases are pending in myri- ad other states and municipalities. In recent are staggering: years, several defendants have attempted to use childhood lead poisoning as a defense $43.4 billion a year, for murder and other crimes. For its part, the industry claims it has been scapegoated. An unnamed lead paint or about 2.2% of total industry spokesperson contends that com- panies were unaware of the potential haz- U.S. health care costs. ards when the paint was applied. At the time it was used, lead paint was widely –Landrigan study touted as a more durable product than Environmental Health Perspectives competing brands that lacked the metal. “[The opposition is] attempting to twist the facts and the law to make us bear health advocates contend. Landrigan lead paint or remove it entirely can cost responsibility,” says Tim Hardy, an attor- points to an article in the January 2000 more than $10,000 per home. Federal ney representing NL Industries, one of the issue of the American Journal of Public efforts to reduce the number of houses defendants in the Rhode Island case. He Health by historians Gerald Markowitz of with deteriorating lead paint are making points to the fact that industry removed City University of New York and David slow progress. HUD’s current program, lead from paint designated for interior use Rosner of Columbia University, which which provides $115 million in grants to 50 years ago as a result of industry-funded states that “beginning in the 1920s, the remove leaded paint entirely or at least studies. However, child advocates point Lead Industries Association and its mem- contain it or stop its deterioration, is out that this ignores the fact that lead was bers conducted an intensive campaign to enough to remediate less than 0.1% of seri- left in exterior paint for another 25 years, promote the use of paint containing white ously dangerous houses, Ryan says. “At that and that exterior paint still posed a threat, lead.” Meanwhile, lead paint was banned rate, it’s not going to take us ten years but by both being used indoors and adding in the 1950s in many other countries one thousand.” lead to outdoor soil. because the data on its toxicity were so Property owners are obligated by exist- Many public health experts and offi- convincing. Even as recently as the early ing laws to appropriately caution, if not cials contend that the lead industry has a 1990s, lead industry–funded representa- protect, tenants from the hazards of lead. history of going to extremes to suppress tives attempted to discredit Needleman’s “Groups of landlords complain about the data that don’t support its cause. In the lead work by promulgating charges of sci- fact that it costs several thousand dollars to 1920s, General Motors influenced investi- entific misconduct against him. After an remove lead from an apartment,” gations into the safety of adding lead to investigation by the Office of Research Landrigan says. “They use that as an excuse gasoline, despite evidence demonstrating Integrity, he was cleared of the allegations for not removing the lead, so children are the ill effects of lead at that time. The lead and exonerated by the scientific community exposed to the lead year after year after paint industry, likewise, knew that lead at large. year. But every year we run up billions of paint was seriously neurotoxic to children, Lead abatement is generally considered more dollars in costs in order to save the but fought against any regulatory effort in the best strategy to prevent new exposures, landlords relatively trivial amounts of the United States for decades, children’s but the cost to contain chipping or peeling money.” Regardless of who should pay—the federal government through taxpayers, culpable businesses or property owners, or We wait until children are individuals—one thing is clear, according to Schettler: “The evidence is strong enough that we ought to be doing what identified with symptoms we can to remove lead from our environ- ment.” Given that the effects of even to take any action, short-term exposure to lead appear per- manent, prevention of such exposures is and even then the action key to protecting children, health policy experts contend. And many now believe is half-hearted, ineffective, prevention may also prove key to reducing future crime waves. The result of cleaning and of course too late. up lead contamination and eventually preventing children’s exposure altogether, –Don Ryan even before birth, could mean a less vio- Alliance to End Childhood Lead Poisoning lent future for all of us.

Julie Wakefield KPT

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