Reduced intellectual development in children with prenatal lead exposure
Por:
Schnaas L., Rothenberg S.J., Flores M.-F., Martinez S., Hernandez C., Osorio E., Velasco S.R., Perroni E.
Publicada:
1 ene 2006
Resumen:
Objective: Low-level postnatal lead exposure is associated with poor intellectual development in children, although effects of prenatal exposure are less well studied. We hypothesized that prenatal lead exposure would have a more powerful and lasting impact on child development than postnatal exposure. Design: We used generalized linear to mixed model with random intercept and slope to analyze the pattern of lead effect of the cohort from pregnancy through 10 years of age on child IQ from 6 to 10 years. We statistically evaluated dose-response nonlinearity. Participants: A cohort of 175 children, 150 of whom had complete data for all included covafiates, attended the National Institute of Perinatology in Mexico City from 1987 through 2002. Evaluations/Measurements: We used the Wechsler Intelligence Scale for Children-Revised, Spanish version, to measure IQ. Blood lead (BPb) was measured by a reference laboratory of the Centers for Disease Control and Prevention (CDC) quality assurance program for BPb. Results: Geometric mean BPb during pregnancy was 8.0 ?g/dL (range, 1-33 ?g/dL), from 1 through 5 years was 9,8 ?g/dL (2.8-36.4 ?g /dL), and from 6 through 10 years was 6.2 ?g/dL (2.2-18.6 ?g/dL). IQ at 6-10 years decreased significantly only with increasing natural-log third-trimester BPb (? = -3.90; 95% confidence interval, -6.45 to -1.36), controlling for other BPb and covariates. The dose-response BPb-IQ function was log-linear, not linear-linear. Conclusions: Lead exposure around 28 weeks gestation is a critical period for later child intellectual development, with lasting and possibly permanent effects. There was no evidence of a threshold; the strongest lead effects on IQ occurred within the first few micrograms of BPb. Relevance to Clinical Practice: Current CDC action limits f6t children applied to pregnant women permit most lead-associated child IQ decreases measured over the studied BPb range.
Filiaciones:
Schnaas L.:
National Institute of Perinatology, Mexico City, Mexico
Rothenberg S.J.:
National Institute of Public Health, Av. Universidad 655, 62508 Cuernavaca, Morelos, Mexico
Centro de Investigaciones y de Estudios Avanzados-Instituto Politécnico Nacional, Merida, Yucatan, Mexico
Flores M.-F.:
National Institute of Perinatology, Mexico City, Mexico
Martinez S.:
National Institute of Perinatology, Mexico City, Mexico
Hernandez C.:
National Institute of Perinatology, Mexico City, Mexico
Osorio E.:
National Institute of Perinatology, Mexico City, Mexico
Velasco S.R.:
Institute for Research in Applied Mathematics and Systems, National Autonomous University of Mexico, Mexico City, Mexico
Perroni E.:
National Institute of Perinatology, Mexico City, Mexico
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