A prospective follow-up study on psychological effects in workers exposed to low levels of lead.

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Abstract
A prospective follow-up study on new Pb workers who began work at a storage battery factory was carried out between 1975-1981. Psychological performances (intelligence, memory, visuomotor functions, vigilance and personality) were assessed before the commencement of exposure and after 1, 2 and 4 yr of work. Of an initial number of 89 workers, 24 were available for the 1-yr, 16 for the 2-yr and 11 for the 4-yr reexamination. The time-weighted average [TWA] blood Pb values ranged between 0.68-2.17 .mu.mol/l (14 and 45 .mu.g/100 ml, respectively). A reference group, nonexposed workers in a cable manufacturing plant and an electrical power plant, was similarly followed. Initially, the average psychological peformances were similar among the Pb workers and the referents. For some psychological tests, learning effect, which was clearly evident among the referents during the follow-up, was almost absent among the Pb workers. The Pb worker''s visual intelligence and visuomotor functions in particular were impaired significantly after the 1st 2 yr of follow-up. When the Pb workers were divided into 2 groups according to the median TWA of the blood Pb values (1.30 .mu.mol/l), the Block Design and the Santa Ana coordination tests were those which best separated the subgroups. Although the impairment of the Pb workers'' performance was slight and the dispersion in the psychological changes was wide, it was evident that some higher nervous functions were affected by Pb levels > .apprx. 1.45 .mu.mol/l.