The past, present and future of childhood lead poisoning

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The past, present and future of childhood lead
poisoning
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• Two Thousand Years of Lead Poisoning
• 1st Century AD. Dioscerides Lead makes the mind
  give way
• 1763. Benjamin FranklinLead in painters,
  printers and tinkers
• 1830 Charles Dickens Uncommercial Traveler
• 1892. Brisbane Australia Childhood lead
  poisoning described
• 1943. Randolph Byers Long term effects
• 1991. PHS Strategic Plan
• 1993 NAS Report

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Five Phases of Lead Toxicology

1. There is no such thing as childhood lead
   poisoning. (1892)

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J Lockhart Gibson
Gibson
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Five Phases of Lead Toxicology

• It exists, but if it doesnt kill you, it
  doesnt touch you (1943)

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Byers
Byers
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Five Phases of Lead Toxicology

• There are long term effects, but only in children
  with severe symptoms (1979)
• Silent lead exposure has long term consequences
• Lead exposure is associated with antisocial
  behavior

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Flaws in Early Studies

• Inadequate exposure markers
• Screening or group measures of outcome
• Inadequate control of confounders
• Potential selection bias

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Responses to Design Issues

• Replaced blood with dentine
• Tested 3500 teeth from 2500 subjects in primary
  school
• Measured 40 covariates adjusted for those that
  were associated with exposure

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Neuropsychological Effects of Lead

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Classroom PerformanceTeachers Ratings
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The Effects of Lead Are Permanent
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The Effects of Lead are Permanent
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Prenatal Lead Exposure
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Newer Studies

• Lanphear et al. Cognitive deficits associated
  with blood lead concentrations lt10 microg/dL in
  US children and adolescents.Public Health Rep.
  2000
• Canfield et al Intellectual impairment in
  children with blood lead concentrations below 10
  microg per deciliter.NEJM 2003
• Bellinger and Needleman Intellectual impairment
  and blood lead levels NEJM 2003

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Slope of Lead/IQ Regression
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Most of the IQ Loss Takes Place at the Lower Dose
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Chiodo et al NTT 2004
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Clues to the Lead/Delinquency link

• Race
• Urban residence
• Low IQ
• ADHD
• Moffits studies

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Case-Control Study
195 adjudicated delinquents, 155 controls Bone
lead levels Cases 11ppm32ppm Controls 1.5
32ppm 10 variates controlled in the analysis Odds
ratio 4.0 ( 1.4-11.1) Population attributable
risk 11-38
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Sales of Leaded Gasoline and Murder Rates
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Robbery and Lead Sales
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The Nature of Aging

• A reduction in molecular fidelity over time
  exceeding the organisms repair capability
• Due to the inherent thermodynamic instability of
  complex molecules

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Processes Associated with the Aging Process

• DNA mutations
• ROS damage
• Mitochondrial damage
• Shortening of telomeres

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Toxic Expressions of Lead

• Mutations Klugs findings
• Mitochondrial damage
• ALAD and mitochondria
• Heme deficiency and neuronal decay

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Lead and t RNA
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Lead and Telomerase

• Sheng Wu Hua Xue Yu Sheng WU Wu Li Xue Bao(
  Shanghai) 2002 34 240-4

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Risk factors Common to Alzheimers and Lead

• Race
• Urbanization
• Autopsy findings Niklowitz
• Apoptosis
• Fetal exposure and later disease

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Changes in APP and ?-actin RNA
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Good Public Health Policy Pays Off
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Doing Well by Doing Good
Study Costs Benefits Profit
CDC 1991 33 Billion 61 Billion 28 Billion
CDC 2002 ---- 110 Billion-319 Billion
Landrigan 43.4 billion
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Reasons for Persistence of Lead Poisoning

• Belief that it is a poor black problem
• Belief that it is a problem of poor child rearing
• Belief that the problem has been solved
• Lack of interest by academic pediatrics
• Efforts of lead industry to disguise the problem
• Belief that we cannot afford to solve the problem

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• When a thing was new, people said
• Its not true.
• When it was shown to be true, people said
• Its not important.
• And when its importance could no longer be
  denied, people saidAnyway, its not new.
• William James