Abstract
Some biological indicators of lead absorption from 23 lead smelters were examined three times. By an accidental a month's discontinuation of exposure, mean concentra-tions of coproporpyrin and delta-aminolevulinic acid in urine decreased to one third, and also positive rates of subjective complaints to one half, but hemoglobin content, stippled cells, polychromatic cells, reticulocytes and lead concentration showed much less improvement. Factor analysis of the indicators revealed the concentration of coproporphyrin in urine had a very different character among them. Ninety three percent of the data matrix of them were explained by the four factors. Mean con-centration of delta-aminolevulinic acid in serum was 35.5±11.4μg/d1 and renal clear-ance and renal reabsorption rate of the substance was 11.2 to 16.9 ml/min and 92.5 to 97.5%, respectively, concerning the six admitted smelters except one case. Concentra-tion of delta-aminolevulinic acid in serum will never be so an excellent indicators, but may be a key substance of delta-aminolevulinic acid and coproporphyrin excretion to urine.
