Low-level lead exposure and cognitive development in early childhood.

The authors studied toddlers with low-level lead exposure to determine whether adverse developmental effects were evident. The study sample consisted of a cohort of 68 children aged 12 to 36 months who had blood lead levels lower than 25 microg/dL on a routine screening in a large urban public hospital clinic. Children with blood lead levels between 10 and 24.9 microg/dL had a mean Mental Developmental Index (Bayley Scales of Infant Development, Second Edition) score that was 6.3 points lower than that of children with blood lead levels between 0 and 9.9 microg/dL (95% confidence interval: 0.6, 11.9). After adjusting for confounders, the difference was 6.2 points (95% confidence interval: 1.7, 10.8). Pediatricians and public health entities should continue in their efforts to reduce the lead burden through environmental control and ongoing surveillance.