δ-Aminolevulinic Acid Dehydrase as a Measure of Lead Exposure

Abstract

Close negative correlation between the concentration of lead in blood (Pb-B) and the logarithm of erythrocyte δ-aminolevulinic acid dehydrase (ALA-D) was found for 159 persons with Pb-B levels ranging from 5μg to 95μg per 100 ml. A statistically significant correlation (r = 0.59) between Pb-B and δ-aminolevulinic acid (ALA) in urine was obtained only for Pb-B values over 50μg/100 ml. These results indicate that erythrocyte ALA-D is more accurate and more sensitive than ALA in urine as an indicator of the amount of circulating lead. It is suggested that ALA-D assays can be used as a screening procedure to exclude a lead absorption over a given level. Fairly accurate estimates of the mean Pb-B of groups of people can also be made from their mean ALA-D activity.