Interrelationships between lead in blood, lead in urine, and ALA in urine during lead work.

28-39. One hundred and seventy-seven workers from a storage battery factory were examined for lead in blood and lead and δ-aminolevulinic acid (ALA) in urine. The workers were selected at random from those who had been employed for more than one month;most had been employed for several years at the same job. Thirty-six workers were from departments with no lead exposure. In three departments with high exposure a rotating system with three weeks' exposure and three weeks' non-exposed work was applied. As the aim of the study was to establish the relationships between the three parameters during constant exposure, the values from these men were treated separately. The relationship between lead in blood and urinary ALA was best described by a curvilineat function: ALA = 10 Pb-, while the regression lines for ALA on lead in urine, and lead in urine on lead in blood were straight. Workers from the departments with the rotating system showed lower values for urinary lead and ALA, compared with non-rotating workers with the same level of lead in blood. All these workers were examined during their second or third week of lead work, with an accumulating lead body burden. This system may be beneficial, especially in departments where prophylactic measures are difficult to install, or for notoriously careless workers. Those who showed comparatively high ALA and urinary lead values in relation to their blood lead level were found to be workers with repeated incidents of metabolic lead influence, in whom the ALA values had seldom been normal. The mean values from different factory departments were of the same order as would be expected from previous studies in storage battery plants. The results are discussed in relation to present concepts of lead absorption and poisoning.