Sparing of cognitive executive functions and impairment of motor functions after industrial exposure to lead: A field study with control group.

Abstract

41 lead-smelter workers and 37 nonsmelter workers were evaluated for cognitive executive function, motor function, and exposure to lead. Smelter workers had an average blood-lead level more than 6 times the Canadian urban average. Multivariate comparisons of the exposed and unexposed groups on all the measures of executive function revealed no trend toward a toxic effect of lead. Canonical correlation analysis (corrected for age and education) of the exposed group revealed no significant relations between dose-related variables and measures of executive function. In analyses of motor-function tests, the multivariate dose-response relationship (corrected for age, weight, and height) indicated a toxic effect of lead (p < .006).

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.…”

“…Although the analysis of variance by exposure group did not reveal significant differences for the other tasks of vigilance and visuomotor speed, step-wise regression analyses documented bone lead as a significant predictor of total errors on a speeded task of auditory information processing (PASAT) and visuomotor speed for the non-preferred hand (simple visual reaction time). 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.…”

“…In a 1994 review, Baker [1994] concluded that among 16 studies dating from 1985, solvent exposed workers showed consistent deficits in short-term memory and psychomotor function. Similarly, chronic exposure to lead at higher concentrations has shown significant reductions in cognitive functions such as memory, learning, and verbal concept formation [Grandjean et al, 1978;Hogstedt et al, 1983;Baker et al, 1984], while more recent studies associate lead exposure with reductions in motor and psychomotor [Balbus et al, 1997] but not higher cognitive function [Ryan et al, 1987;Stollery et al, 1989;Braun and Daigneault, 1991]. In one of the few studies to directly compare workers exposed to solvents vs. workers exposed to organic and inorganic lead, Bolla et al [1995] reported that both the lead-and solvent-exposed groups exhibited poorer manual dexterity and executive/motor function than controls.…”

Neurobehavioural testing in workers occupationally exposed to lead: systematic review and meta-analysis of publications

“…In some cases, the differences in mean values reported by different studies leads one to question whether these studies did, indeed, use the same tests. For example, for simple reaction time (non-preferred hand), Braun and Daigneault, 26 Haenninen et al, 28 and Repko et al 34 reported means for the exposed groups of 178.78, 1310, and 29.62, respectively. The source of such discrepancy is not apparent, although it is possible that different studies used different numbers of items.…”