Erythrocyte delta-aminolevulinic acid dehydratase in new lead exposure: a longitudinal study.

Abstract

The time course of the lead-induced inhibition of erythrocyte δ-aminolevulinic acid dehydratase (ALA-D) was studied in 29 new lead workers. Samples were performed before commencement of exposure, two to three times during the first week, once a week for three months, and twice during the fourth month of exposure. The rise of the concentration of lead in the blood (Pb-B) was accompanied by a rapid decrease of ALA-D activity, measurable even during the first days of exposure. The rate of decrease of ALA-D was proportional to the rise in Pb-B. After ALA-D had reached a steady state, the variation within each subject was very small. Since ALA-D activity fell in all 29 subjects, the causative effect of lead must be considered proven. ALA-D provides a sensitive and accurate measure of circulating lead. The test is reliable even during the first few days of initial exposure.