Evaluation of lead exposure in workers at a lead-acid battery factory in Korea: With focus on activity of erythrocyte pyrimidine 5'-nucleotidase (P5N)

Objective - To evaluate lead exposure - among lead-acid battery workers in Korea, to evaluate in more detail the erythrocyte pyrimidine 5'-nucleotidase (P5N) test for lead exposure, and to evaluate the abnormal accumulation of erythrocyte pyrimidine nucleotides in the battery workers. Methods - Activity of P5N and other biological variables were examined in 66 exposed workers in a lead-acid battery factory and in 26 non-exposed workers in Korea. Results - At the factory the time-weighted average of 13 (72%) of 18 air samples for lead exceeded 0.05 (range 0.012-0.468) mg/m³. Blood lead concentration (PbB) in 39 of the 66 exposed workers was above 40 μg/dl, and the mean (SD) PbB in the exposed group was 45.7 (15.7) μg/dl. Compared with the non-exposed group, free erythrocyte protoporphyrin in the exposed group was significantly increased, whereas erythrocytes P5N activity and activity of erythrocyte δ-arninolevulinic acid dehydratase (ALAD) were significantly inhibited. Erythrocyte P5N activity had valid correlation biologically with PbB and with other biological variables, such as ALAD activity. In 28 exposed workers, the concentration of erythrocyte pyrimidine nucleotides (uridine 5'-diphosphate-glucose and cytidine 5'-triphosphate) correlated inversely with P5N activity and positively with PbB. Conclusions - These findings show that the depression of erythrocyte P5N activity by lead exposure results in the accumulation of erythrocyte pyrimidine nucleotides. In general, the standard analysis of PbB performed in laboratories around the world remains the most useful index of recent exposure. The results indicate that the erythrocyte P5N activity test provides supporting evidence of lead exposure and shows the effect of lead on nucleotide metabolism.