Occupational lead exposure of storage battery workers in Korea

Two hundred and thirty-four lead workers employed in a storage battery factory in Korea were examined for lead in blood (PbB) and urine (PbU). delta-aminolaevulinic acid in urine (ALAU), coproporphyrin in urine (CPU), and haemoglobin. The dose-response relationship between PbB and ALAU suggested that a PbB below 50-60 micrograms/dl is a proper practical limit of biological monitoring for lead workers. The inter-relationship between PbB and ALAU or PbU was better explained by a segmental straight function than by a curvilinear function. Inclusion of data from workers whose PbB was below 30-40 micrograms/dl, if they comprise a relatively large proportion of the whole, seems to have a role as a dummy effect on the overall regression function causing the curvilinear trend. At a given blood lead concentration, the ALAU of lead workers increased with an increase in the duration of exposure. This could be explained by the chronic effect of lead on haem precursors. Semi-quantitative measurement of CPU still played an important part in the screening of lead workers due to its simplicity, showing high sensitivity (97.8%) in detecting lead workers with PbB of 60 micrograms/dl or over.