Lead exposure and the motor developmental status of urban six-year-old children in the Cincinnati Prospective Study

The relationship between asymptomatic lead exposure and subtle deficits in intellectual attainment has been relatively well established by modern studies. However, neuromotor performance has rarely been the focus of these investigations. It was postulated that motor developmental outcomes may be more sensitive indicators of lead's adverse effects on the central nervous system as they are probably less confounded with social factors than cognitive and academic outcomes. A comprehensive neuromotor assessment battery was administered to 245 six-year-old urban inner-city children enrolled in the Cincinnati Lead Study. These children have been followed since birth with quarterly assessments of blood lead concentrations, medical status, and neurobehavioral development. Prior to covariate adjustment, neonatal, but not prenatal blood lead levels were associated with poorer scores on assessments of bilateral coordination, upper-limb speed and dexterity, and a composite index of fine-motor coordination. Averaged postnatal blood lead levels were also associated with lower scores on the aforementioned subtests as well as a measure of visual-motor control. Following statistical adjustment for covariates, neonatal blood lead levels were associated with poorer performance on a measure of upper-limb speed and dexterity and the fine-motor composite. Postnatal blood lead levels remained significantly associated with poorer scores on measures of bilateral coordination, visual-motor control, upper-limb speed and dexterity, and the fine-motor composite. Low to moderate lead exposure is associated with moderate deficits in gross and especially fine-motor developmental status. Results of this study provide support for recent initiatives to reduce the exposure of children to sources of environmental lead.