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Cited by 2,205Heavy Metal Exposure and ToxicityHeavy metals in environmentMercury impact and mitigation studies

Low-Level Environmental Lead Exposure and Children’s Intellectual Function: An International Pooled Analysis

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Lanphear, Bruce P., Hornung, Richard, Khoury, Jane, Yolton, Kimberly, Baghurst, Peter, Bellinger, David C., Canfield, Richard L., Dietrich, Kim N. +8 more·2005·Environmental Health Perspectives
DOI 10.1289/ehp.7688PMC PMC1257652
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Abstract

Lead is a confirmed neurotoxin, but questions remain about lead-associated intellectual deficits at blood lead levels < 10 μg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. The objective of this study was to examine the association of intelligence test scores and blood lead concentration, especially for children who had maximal measured blood lead levels < 10 μg/dL. We examined data collected from 1,333 children who participated in seven international population-based longitudinal cohort studies, followed from birth or infancy until 5–10 years of age. The full-scale IQ score was the primary outcome measure. The geometric mean blood lead concentration of the children peaked at 17.8 μg/dL and declined to 9.4 μg/dL by 5–7 years of age; 244 (18%) children had a maximal blood lead concentration < 10 μg/dL, and 103 (8%) had a maximal blood lead concentration < 7.5 μg/dL. After adjustment for covariates, we found an inverse relationship between blood lead concentration and IQ score. Using a log-linear model, we found a 6.9 IQ point decrement [95% confidence interval (CI), 4.2–9.4] associated with an increase in concurrent blood lead levels from 2.4 to 30 μg/dL. The estimated IQ point decrements associated with an increase in blood lead from 2.4 to 10 μg/dL, 10 to 20 μg/dL, and 20 to 30 μg/dL were 3.9 (95% CI, 2.4–5.3), 1.9 (95% CI, 1.2–2.6), and 1.1 (95% CI, 0.7–1.5), respectively. For a given increase in blood lead, the lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 μg/dL was significantly greater than that observed for those with a maximal blood lead level ≥7.5 μg/dL (p = 0.015). We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 μg/dL is associated with intellectual deficits.

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  • Prior studies document a significant correlation between childhood lead levels less than 10 ug/ml and cognitive and behavioral outcomes including ADHD and hyperactivity.

    “Chandramouli, Ellis, and Emond (2009); Canfield et al. (2003); Lanphear et al. (2005); Nigg et al. (2010); and Wasserman et al. (1997) all document a significant correlation between lead levels less than 10 milograms per deciliter (ug/ml) during childhood and cognitive and behavioral outcomes including ADHD and hyperactivity.”

    From Do Low Levels of Blood Lead Reduce Children's Future Test Scores? (2018) · cites this paper as Lanphear et al. (2005)

    The Abstract and Discussion (page numbers unavailable) report a significant association between blood lead below 10 μg/dL and lower childhood IQ. The paper does not report ADHD or hyperactivity outcomes at those levels; its discussion of behavioral problems refers to lead levels above 10 μg/dL. The citing sentence also gives the concentration unit incorrectly: the paper uses μg/dL. (LLM, conf=0.90)

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  1. Belsley DA Kuh E Welsch RE1980. Regression Diagnostics. New York:John Wiley and Sons.

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Authors
Lanphear, B. P., Hornung, R., Khoury, J., Yolton, K., Baghurst, P., Bellinger, D. C., Canfield, R. L., Dietrich, K. N., Bornschein, R., Greene, T., Rothenberg, S. J., Needleman, H. L., Schnaas, L., Wasserman, G., Graziano, J., & Roberts, R.
Affiliations
  • Cincinnati Children's Hospital Medical Center (US)
  • Women's and Children's Hospital (AU)
  • Boston Children's Hospital (US)
  • Cornell University (US)
  • University of Cincinnati (US)
  • Cleveland Clinic (US)
  • Instituto Nacional de Salud Pública (MX)
  • University of Pittsburgh (US)
  • Instituto Nacional de Perinatología (MX)
  • Columbia University (US)
  • Griffith University (AU)
ORCID
Venue
Environmental Health Perspectives
Publisher
American Chemical Society (ACS)
Published
2005-03-18
Volume
113
Issue
7
Pages
894-899
ISSN
  • 0091-6765 (ISSN-L)
  • 1552-9924
DOI
10.1289/ehp.7688
PMC
PMC1257652
OpenAlex
W2126489758
Cited by
2,205
References
54
Citations by year
2026: 112 · 2025: 83 · 2024: 95 · 2023: 77 · 2022: 131 · 2021: 112 · 2020: 125 · 2019: 132 · 2018: 114 · 2017: 128 · 2016: 108 · 2015: 110 · 2014: 131 · 2013: 133 · 2012: 111
FWCI
49.30
Type
journal article
Language
en
Open access
Licence
Locations
  • Environmental Health Perspectives (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, public-domain)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion, public-domain)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Digital Access to Scholarship at Harvard (DASH) (Harvard University) (submittedVersion, cc-by)
  • Adelaide Research & Scholarship (AR&S) (University of Adelaide) (submittedVersion, other-oa)
  • Griffith Research Online (submittedVersion)
Topics
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Heavy Metal Exposure and Toxicity
  • Physical Sciences › Environmental Science › Pollution › Heavy metals in environment
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Mercury impact and mitigation studies
Keywords
lead exposure, blood lead levels, child intelligence, IQ, neurotoxicity, low-level lead exposure, dose-response relationship, children, environmental lead
MeSH terms
Child, Child, Preschool, Environmental Exposure, Female, Humans, Infant, Infant, Newborn, Intelligence, Intelligence Tests, Lead, Longitudinal Studies, Male, Cohort Studies

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