No abstract

For a prospective study of lead exposure and early development, we recruited pregnant women from a lead smelter town and from an unexposed town in Yugoslavia and followed their children through 7 years of age. In this paper we consider associations between lifetime lead exposure, estimated by the area under the blood lead (BPb) versus time curve (AUC7), and intelligence, with particular concern for identifying lead's behavioral signature. The Wechsler Intelligence Scales for Children-Version III (WISC-III) was administered to 309 7-year-old children, 261 of whom had complete data on intelligence, blood lead, and relevant sociodemographic covariates (i.e., Home Observation for the Measurement of the Environment (HOME), birth weight, gender, sibship size, and maternal age, ethnicity, intelligence, and education). These showed anticipated associations with 7-year intelligence, explaining 41-4% of the variance in Full Scale, Performance, and Verbal IQ. Before covariate adjustment, AUC7 was unrelated to intelligence; after adjustment, AUC7 explained a significant 2.8%-4.2% of the variance in IQ. After adjustment, a change in lifetime BPb from 10 to 30 micro/dl related to an estimated decrease of 4.3 Full Scale IQ points; estimated decreases for Verbal and Performance IQ were 3.4 and 4.5 points, respectively. AUC7 was significantly and negatively related to three WISC-III factor scores: Freedom from Distractibility, Perceptual Organization, and Verbal Comprehension; the association with Perceptual Organization was the strongest. Consistent with previous studies, the IQ/lead association is small relative to more powerful social factors. Findings offer support for lead's behavioral signature; perceptual-motor skills are significantly more sensitive to lead exposure than are the language-related aspects of intelligence.ImagesFigure 1. AFigure 1. BFigure 1. CFigure 1. DFigure 2.

No abstract

OBJECTIVES: Interpreting associations between lead exposure and child behavior problems is difficult because studies have not controlled for sociodemographic confounders or have used shed teeth to mark exposure. This study explored associations between blood lead and preschool behavior. METHODS: Children from a smelter town and a non-lead-exposed town in Yugoslavia were followed up prospectively from pregnancy through age 3. The Child Behavior Checklist was used to assess behavior problems in 379 3-year-olds, controlling for sociodemographic factors and difficult infant temperament. RESULTS: Multiple regression revealed the expected significant associations between checklist subscales and sociodemographic factors, which explained 7% to 18% of the variance on the subscales. Concurrent blood lead explained a significant 1% to 4% of the variance on the Destructive and Withdrawn subscales. Earlier difficult temperament explained an additional 2% to 5% of the checklist variance. Scores on the Destructive subscale were consistently associated with blood lead. As blood lead increased from 10 to 20 micrograms/dL, subscale scores increased by approximately 0.5 points. CONCLUSIONS: Lead/behavior associations are significant but small compared with the effects of social factors.