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

By B. Lanphear, R. Hornung, J. Khoury, K. Yolton, P. Baghurst, D. Bellinger, R. Canfield, K. Dietrich, R. Bornschein, T. Greene and 6 more. Environmental Health Perspectives, 2005

2,203 citations recorded by the source corpus.

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.

Subfields: Health, Toxicology and Mutagenesis, Pollution

View Paper: https://www.semanticscholar.org/paper/429ae2a1736409c0dbe0d2f75ab5ed9b3f2e7b49

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

1. James M. Swanson
2. Marcel Kinsbourne
3. J. Nigg
4. B. Lanphear
5. G. Stefanatos
6. Nora D. Volkow
7. Tanya E. Froehlich
8. E. Taylor

Citations in the corpus

• Exposures to Environmental Toxicants and Attention Deficit Hyperactivity Disorder in U.S. Children (2006, background): “Although several recent studies have linked lead to IQ deficits at blood lead levels < 10 µg/dL (Bellinger and Needleman 2003; Canfield et al. 2003; Lanphear et al. 2005)—the current action level set by the Centers for Disease Control and Prevention (CDC)—it remains unclear whether blood lead…”
• Etiologic Subtypes of Attention-Deficit/Hyperactivity Disorder: Brain Imaging, Molecular Genetic and Environmental Factors and the Dopamine Hypothesis (2007, background): “Lanphear et al. (2006) reviewed the literature on the effects of low levels of lead on intellectual development, and performed a joint analysis of data from multiple groups that had assessed the effects of low levels of lead on IQ.”
• Pb Neurotoxicity: Neuropsychological Effects of Lead Toxicity (2014, positive): “…failed to find evidence of a threshold for neurological effects; recent large-scale, prospective studies suggest that blood lead levels below 10 𝜇 g/dL significantly worsen intellectual functioning in children and that the strength of association is stronger at the low range of exposure [20–22].”