Low level lead exposure and neuropsychological functioning in blue collar males

To examine the interrelationships between normal aging, occupational lead exposure, and cognitive functioning, a comprehensive battery of neuropsychological tests was administered to 288 randomly-selected lead-exposed workers and 181 demographically-similar nonexposed controls. Contrary to previous reports, those workers with current blood-lead levels in the low to moderate range (less than 50 micrograms/dl) were found to perform as well as controls on measures of learning, memory, attention, visuospatial ability, and general intelligence. They differed from controls only on one measure of psychomotor speed and manual dexterity, the Grooved Pegboard Test, and these between-group differences were restricted to the older lead workers. It is likely that these results are secondary to lead-mediated neuromuscular damage. There is little support for the view that older adults with current blood lead levels in the low to moderate range are at risk for developing significant CNS dysfunction, even though they may have had a past history of excessively high blood lead levels.