Associations of blood lead, dimercaptosuccinic acid-chelatable lead, and tibia lead with neurobehavioral test scores in South Korean lead workers

The authors performed a cross-sectional study to evaluate associations betw een blood lead, tibia lead, and dimercaptosuccinic acid (DMSA)-chelatable l ead and measures of neurobehavioral and peripheral nervous system function among 803 lead-exposed workers and 135 unexposed controls in South Korea. T he workers and controls were enrolled in the study between October 1997 and August 1999. Central nervous system function was assessed with a modified version of the World Health Organization Neurobehavioral Core Test Battery. Peripheral nervous system function was assessed by measuring pinch and gri p strength and peripheral vibration thresholds. After adjustment for covari ates, the signs of the beta coefficients for blood lead were negative for 1 6 of the 19 tests and blood lead was a significant predictor of worse perfo rmance on eight tests. On average, for the eight tests that were significan tly associated with blood lead levels, an increase in blood lead of 5 mug/d l was equivalent to an increase of 1.05 years in age. in contrast, after ad justment for covariates, tibia lead level was not associated with neurobeha vioral test scores. Associations with DMSA-chelatable lead were similar to those for blood lead. In these currently exposed workers, blood lead was a better predictor of neurobehavioral performance than was tibia or DMSA-chel atable lead, mainly in the domains of executive abilities, manual dexterity , and peripheral motor strength.