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Age of greatest susceptibility to childhood lead exposure: a new statistical approach

Richard W Hornung1, Bruce P Lanphear, Kim N Dietrich

  • 1Cincinnati Children's Environmental Health Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA. richard.hornung@cchmc.org

Environmental Health Perspectives
|August 13, 2009
PubMed

Insights

Children aged 6 years with higher blood lead levels (BPb) show greater cognitive and behavioral deficits. This finding challenges the assumption that early childhood is the period of greatest lead susceptibility.

Area of Science:

  • Environmental Health
  • Pediatric Toxicology
  • Neurodevelopmental Science

Background:

  • Lead toxicity susceptibility is often assumed to be highest in early childhood.
  • Recent studies indicate a stronger association between blood lead concentrations (BPb) at 5-7 years and IQ.
  • This suggests a potential shift in the age of greatest susceptibility.

Purpose of the Study:

  • To determine the age of greatest susceptibility to lead exposure.
  • To employ an innovative statistical approach to overcome challenges with correlated serial BPb measurements.

Main Methods:

  • Analysis of two child cohorts (Rochester, NY; Cincinnati, OH) from infancy to 6 years.
  • Serial BPb measurements and IQ testing at 6 years of age.
  • Statistical modeling including the ratio of 6-year BPb to 2-year BPb to assess the impact of BPb profiles on IQ.

Main Results:

  • The ratio of BPb at 6 years to BPb at 2 years significantly impacted IQ (p < .001).
  • A 50% increase in 6-year BPb relative to 2-year BPb correlated with a 7.0-point decrease in IQ.
  • Higher 6-year BPb relative to 2-year BPb was also associated with a 3.35-fold increase in criminal arrest rates.

Conclusions:

  • Blood lead concentrations at 6 years of age are more strongly associated with cognitive and behavioral development than earlier childhood measurements.
  • This highlights later childhood as a critical period for lead exposure effects.
Abstract

Keywords:
age effectsblood leadcollinearitytemporal pattern

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