Evaluation of lead exposure in workers at secondary lead smelters in South Korea: with focus on activity of erythrocyte pyrimidine 5 -nucleotidase ž P5N/

To evaluate lead exposure among secondary lead-smelting workers with a focus on erythrocyte pyrimidine 5 -nucleotidase ŽP5N. activity, blood lead concentration ŽPbB., activity of P5N and other biological variables were examined in 88 exposed workers in five secondary lead smelters and in 24 non-exposed workers in Korea. All of the mean values of air lead concentration ŽPbA. in the three processes, scrap pretreatment, blast furnace smelting, and refining and casting of the secondary lead smelters, markedly exceeded 0.05 mg m3. In this survey, 29 Ž97%. of 30 air samples for lead exceeded 0.05 mg m3. The highest mean PbA and PbB values were found in the section of blast furnace smelting. All of the mean PbB values in all the sections were higher than 30 g dl. PbB of 71 Ž81%. of the 88 exposed workers exceeded 30 g dl. In 31 Ž35%. of the exposed workers, PbB was above 60 g dl. Compared with the non-exposed group, zinc protoporphyrin ŽZPP. in the exposed group was significantly increased, whereas erythrocyte P5N activity and activity of erythrocyte -aminolevulinic acid dehydratase ŽALAD. were significantly inhibited. Erythrocyte P5N activity had valid biological correlation with PbB and with other biological variables, such as ALAD activity or ZPP. Lead exposure affected hemoglobin levels via inhibition of P5N activity, as well as the heme biosynthetic pathway, in the high-exposure state.