A NEUROBEHAVIORAL STUDY OF LONG-TERM OCCUPATIONAL INORGANIC LEAD-EXPOSURE

A group of 38 male workers at a secondary smelter (period of employmen t 2-35 years; median 10 years) was divided into two subgroups dependin g on bone-lead concentration, arranged as 19 matched pairs according t o age, education and job level. The median concentrations for finger-b one lead (Bone-Pb) were 16 vs. 32 mu g/g; for current blood-lead (B-Pb ), 1.6 vs. 1.8 mu mol/l; for retrospective peak blood-lead (Peak-Pb), 2.7 vs. 3.0 mu mol/l; and for a retrospective cumulative blood lead in dex (CBLI), 143 vs. 233 mu mol/l X months. Nineteen unexposed male wor kers from a nearby mechanical plant served as controls, using the same matching algorithm. The triplets were examined with a standardised ne uropsychological test battery, and four questionnaires for self-rating of symptoms and activity/stress level related to work environment. No sign of behavioural deterioration was observed in the exposed groups, either in objective cognitive tests or in subjective symptom/mood sel f-rating scales. Despite the limited sample size, the statistical powe r was sufficient to conclude that a concealed lead-associated effect w as unlikely. Covariations between behavioural measures and lead exposu re indices were generally low and non-significant, as a whole not exce eding a random level. No confounding or effect-modifying factor was de tected that could explain the results as a type II error. To conclude, a current B-Pb of 1.8 mu mol/l was not associated with adverse behavi oural effects, and a long-term lead exposure around 2.0 mu mol/l for 1 3 years (mean values) was not associated with permanent brain dysfunct ion. (C) Elsevier Science B.V.