Intellectual Impairment in Children with Blood Lead Concentrations below 10 μg per Deciliter

The relation between lead concentrations below 10 μg per deciliter (0.483 μmol per liter) and intellectual impairment is not well understood. In this prospective study, an increase in the peak blood lead concentration from 1 to 10 μg per deciliter during several measurements in early life was associated with a 7.4-point reduction in IQ at the age of five years, after adjustment for maternal IQ and other potential confounders. Even a low blood lead concentration may adversely affect cognitive development. Lead is neurotoxic, and young children are at particular risk for exposure. 1 Numerous studies indicate that blood lead concentrations above 10 μg per deciliter (0.483 μmol per liter) are associated with adverse outcomes on measures of intellectual functioning and social–behavioral conduct. 2 – 9 Such studies led to the identification of a blood lead concentration of 10 μg per deciliter or higher as a “level of concern” by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). 1 , 10 It remains unclear whether lead-associated cognitive deficits occur at concentrations below 10 μg per deciliter. The CDC and WHO . . .