The effects of absorption of low concentrations of inorganic lead (7439921) (Pb) on worker behavior and neurologic function were studied. For one year, exposed and unexposed workers were subjected to performance and behavioral test measurements, neurological and electroneuromyographic examinations, and examination of biologic samples. The 140 examined workers (85 were lead exposed, 55 nonexposed) were in the storage battery manufacturing industry. The lead exposed group had a mean blood lead (PbB) of 46 micrograms per 100 milliliters, whereas the control group had 17 micrograms Pb per 100 milliliters. PbB aminolevulinic-acid-dehydrase, free erythrocyte PbB, protoporphyrin (FEP), urine lead, and aminolevulinic-acid were intercorrelated, and each measure could be predicted from the others. Except for a positive relationship between FEP and certain pure tone threshold measures, none of the biomedical indices had a significant relationship to the nerve conduction velocities (NCV) or behavioral measures. The lead exposed workers showed a statistically significant lower NCV in the magnitude of 5 to 9 meters per second for the conduction velocity measure of the median, ulnar posterior tibial, and deep peroneal nerves. Deficits in visual reaction time, under response control of the ulnar nerve, as well as deficits in auditory functioning, in terms of pure tone thresholds and tone decay, occurred in lead exposed workers. The authors conclude that low lead absorption (below 80 micrograms Pb per 100 milliliters of blood) caused quantifiable behavioral and neurological impairment in these workers. They suggest that individual workers be assessed for behavioral and neurological functional impairment.
U.S. Department of Health, Education, and Welfare, NIOSH, Cincinnati, Ohio