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Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach

BACKGROUND: Susceptibility to lead toxicity is often assumed to be greatest during early childhood (e.g., 2 years of age), but recent studies suggest that blood lead concentrations (BPb) taken at 5–7 years of age are more strongly associated with IQ. OBJECTIVE: We aimed to determine the age of great...

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Detalles Bibliográficos
Autores principales: Hornung, Richard W., Lanphear, Bruce P., Dietrich, Kim N.
Formato: Texto
Lenguaje:English
Publicado: National Institute of Environmental Health Sciences 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2721877/
https://www.ncbi.nlm.nih.gov/pubmed/19672413
http://dx.doi.org/10.1289/ehp.0800426
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author Hornung, Richard W.
Lanphear, Bruce P.
Dietrich, Kim N.
author_facet Hornung, Richard W.
Lanphear, Bruce P.
Dietrich, Kim N.
author_sort Hornung, Richard W.
collection PubMed
description BACKGROUND: Susceptibility to lead toxicity is often assumed to be greatest during early childhood (e.g., 2 years of age), but recent studies suggest that blood lead concentrations (BPb) taken at 5–7 years of age are more strongly associated with IQ. OBJECTIVE: We aimed to determine the age of greatest susceptibility to lead exposure using an innovative statistical approach that avoids the problem of correlated serial BPb measurements. METHODS: We analyzed two cohorts of children that were followed from infancy to 6 years of age in Rochester, New York (n = 211), and Cincinnati, Ohio (n = 251). Serial BPb levels were measured and IQ tests were done when children were 6 years of age. After adjustment for relevant covariates, the ratio of 6-year BPb to 2-year BPb was added to the multiple regression model to test whether the pattern of BPb profiles during childhood had additional effect on IQ. RESULTS: The ratio of BPb at 6 years to the BPb at 2 years showed a strong effect on IQ (p < .001) when added to the multiple regression model that included the average childhood BPb. IQ decreased by 7.0 points for children whose BPb at 6 years of age was 50% greater than that at 2 years compared with children whose 6-year BPb was 50% less than their 2-year BPb. Similarly, criminal arrest rates were a factor of 3.35 higher for those subjects whose 6-year BPb was 50% higher than their 2-year BPb. CONCLUSIONS: We conclude that 6-year BPb is more strongly associated with cognitive and behavioral development than is BPb measured in early childhood.
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spelling pubmed-27218772009-08-11 Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach Hornung, Richard W. Lanphear, Bruce P. Dietrich, Kim N. Environ Health Perspect Research BACKGROUND: Susceptibility to lead toxicity is often assumed to be greatest during early childhood (e.g., 2 years of age), but recent studies suggest that blood lead concentrations (BPb) taken at 5–7 years of age are more strongly associated with IQ. OBJECTIVE: We aimed to determine the age of greatest susceptibility to lead exposure using an innovative statistical approach that avoids the problem of correlated serial BPb measurements. METHODS: We analyzed two cohorts of children that were followed from infancy to 6 years of age in Rochester, New York (n = 211), and Cincinnati, Ohio (n = 251). Serial BPb levels were measured and IQ tests were done when children were 6 years of age. After adjustment for relevant covariates, the ratio of 6-year BPb to 2-year BPb was added to the multiple regression model to test whether the pattern of BPb profiles during childhood had additional effect on IQ. RESULTS: The ratio of BPb at 6 years to the BPb at 2 years showed a strong effect on IQ (p < .001) when added to the multiple regression model that included the average childhood BPb. IQ decreased by 7.0 points for children whose BPb at 6 years of age was 50% greater than that at 2 years compared with children whose 6-year BPb was 50% less than their 2-year BPb. Similarly, criminal arrest rates were a factor of 3.35 higher for those subjects whose 6-year BPb was 50% higher than their 2-year BPb. CONCLUSIONS: We conclude that 6-year BPb is more strongly associated with cognitive and behavioral development than is BPb measured in early childhood. National Institute of Environmental Health Sciences 2009-08 2009-05-07 /pmc/articles/PMC2721877/ /pubmed/19672413 http://dx.doi.org/10.1289/ehp.0800426 Text en http://creativecommons.org/publicdomain/mark/1.0/ Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, ?Reproduced with permission from Environmental Health Perspectives?); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Research
Hornung, Richard W.
Lanphear, Bruce P.
Dietrich, Kim N.
Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title_full Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title_fullStr Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title_full_unstemmed Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title_short Age of Greatest Susceptibility to Childhood Lead Exposure: A New Statistical Approach
title_sort age of greatest susceptibility to childhood lead exposure: a new statistical approach
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2721877/
https://www.ncbi.nlm.nih.gov/pubmed/19672413
http://dx.doi.org/10.1289/ehp.0800426
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