EFFECTS OF LOW-LEVEL EXPOSURE TO LEAD ON NEUROPHYSIOLOGICAL FUNCTIONSAMONG LEAD BATTERY WORKERS

Objectives-Assessment of neurophysiological functions in workers with low level exposure to lead and evaluation of the efficacy of bone lead measurements in the prediction of effects of lead. Methods-Exposure t o lead of 60 workers from a lead battery factory was estimated from hi storical blood lead measurements and analysis of lead in the tibial an d calcaneal bones with X. ray fluorescence. Peripheral and central ner vous system functions were assessed by measuring conduction velocities , sensory distal latencies, sensory amplitudes, and vibration threshol ds as well as by quantitative measurement of the absolute and relative powers and mean frequencies of different electroencephalograph (EEG) channels. Results-Sensory amplitudes, and to a smaller degree sensory or motor conduction velocities, showed a negative correlation with lon g term exposure to lead, most clearly with integrated blood lead conce ntration and exposure time. Vibration thresholds measured in the arm w ere related to recent exposure to lead, those measured in the leg to l ong term exposure. The alpha and beta activities of the EEG were more abundant in subjects with higher long term exposure to lead. Calcaneal lead content reflected short term exposure, tibial lead content refle cted long term exposure. Blood lead history showed a closer relation w ith effects of lead than the tibial or calcaneal lead concentrations. Conclusions-Vibratory thresholds, quantitative EEG, and to a smaller e xtent the sensory amplitude, provide sensitive measures of effects of lead in occupationally exposed adults. Most accurate estimates of heal th risks induced by lead can be obtained from a good history of blood lead measurements. If such a history of blood lead concentrations is n ot available, analysis of bone lead may be used for the assessment of health risks.