Comparison of neurobehavioral function in workers exposed to a mixture of organic and inorganic lead and in workers exposed to solvents

Abstract

The neurobehavioral effects of lead (organic and inorganic) and organic solvents were compared in 386 U.S. workers (52 reference, 190 lead, and 144 solvent workers). The association between neurobehavioral test performance and duration of exposure to lead or solvents was also examined and compared. The neurobehavioral test battery consisted of examiner and computer-administered neurobehavioral tests, a test of olfactory function, and questionnaires that assessed neuropsychiatric symptoms. Adjusted mean differences on the neurobehavioral test scores were estimated by comparing the exposed group to the referent group using linear regression and adjusting for premorbid intellectual ability, age, and race. Both lead and solvents were associated with diminished neurobehavioral performance in all neurobehavioral areas tested. Specifically, while lead and solvent exposure had the same magnitude of adverse effects on tests of manual dexterity, lead exposure was associated with greater adverse effects on memory and learning tests but with less adverse effects on executive/motor tests and on a test of olfaction than solvent exposure. An elevated number of neuropsychiatric symptoms was reported by 7% of the referent group, 43% of the lead group, and 15% of the solvent group. For exposure duration of < or = 10 years, more neurobehavioral decrements were found in the solvent group relative to the lead group. However, for exposure duration of > or = 18 years, the lead group showed more decrements than the solvent group. Overall, these data suggest differences in neurobehavioral functioning between the lead (organic and inorganic) and solvent exposed workers examined in this study.

Cognitive effects of chronic exposure to lead and solvents

“…These findings are consistent with previous studies of chronic lead exposure where higher exposures (e.g., years of exposure; integrated blood lead (IBL); bone lead) were associated with poorer performance on motor and visuomotor tasks [Braun and Daigneault, 1991;Bolla et al, 1995;Lindgren et al, 1996;Bleecker et al, 1997;Payton et al, 1998]. However, Hanninen et al [1998] and Bleecker et al [1997] found that history of blood lead was a better predictor of performance than bone lead while Stokes et al [1998] did not find an association between bone lead and neurobehavioral performance.…”

“…This task, in both its traditional form as a part of the Wechsler Adult Intelligence Scales or its computerized form, has consistently been shown to be sensitive to the chronic effects of both lead and solvents [Grandjean et al, 1978;Valciukas et al, 1978;Bolla et al, 1990Bolla et al, , 1995Spurgeon et al, 1992;Baker, 1994;Grosch et al, 1996; Lindgren et al, 1996;Seeber et al, 1996]. However, in the present study, only those workers chronically exposed to lead performed significantly more slowly but not less accurately than controls.…”

Neuropsychiatric Effects in Workers with Occupational Exposure to Carbon Disulfide

“…7.2 compared to 4.7 in the control group (p < 0.01) 39) . In other studies with usually lower exposure to organic solvents, the mean number of positive answers was much lower, e.g., 1.9 in US workers exposed to a mixture of solvents 31) , 3.2 in English paintmakers 30) , in 3.1 Swedish workers exposed to styrene 37) , and 2.9 in Chinese printing and paint workers 25) , etc. In the German study in which a slightly modified questionnaire was used-having 18 instead of 16 questions, the mean number of positive answers was 2.9 for 544 male painters 41) .…”

“…Exposure to CS 2 ranging from 3 mg/m 3 to 147 mg/m 3 in a viscose rayon factory in Belgium, had no significant effect on memory or attention 7) . The Swedish questionnaire for neuropsychiatric symptoms Q16 has been used in many occupational groups in different countries exposed to various hazards, mostly to organic solvents 14,[24][25][26][27][28][29][30][31][32][33] , but also to lead 31,34) , welder's metals 35) , styrene [36][37][38] , pesticides 39) and manganese 40) , etc. But in the literature we did not find any implementation of the questionnaire in workers exposed to CS 2 , a well known neurotoxic agent.…”

Longitudinal Study to Explore Chronic Neuropsychologic Effects on Solvent Exposed Workers

“…This indicates reduced attention and visomotoric ability. Bolla et al 29) also reported significant effects concerning the TMT in workers of a paint factory, whereas Lundberg et al 27) did not find significant differences in painters. Spurgeon counted 4 out of 6 studies showing significant solvent related effects concerning the TMT 4 .…”