Objectives-To determine if measures reflecting chronic occupational lead exposure are associated with performance on neuropsychological tests. Method-467 Canadian male lead smelter workers (mean (SD) age 43*4 (11.00) years, education 9-8 (3.18) years, years of employment 17'7 (7.43), and current blood lead concentration (B-Pb) 27-5 (8.4) ug dl-e) were given a neuropsychological screening battery. Time weighted average (TWA) and time integrated blood levels (IBL) were developed from B-Pb records obtained through regular medical monitoring (mean (range) TWA 40-1 (4-0-66.4) jg di-1, mean IBL 765*2 (0'6-1625-7) pg-y dl-1). 14 exposure measures may mask differences in neuropsychological functioning related to chronic, low dose exposure.'7 Measures of chronic exposure include time weighted average (TWA), a weighted average of B-Pb over the duration of exposure, and time integrated B-Pb (IBL), a measure of cumulative B-Pb concentrations over the period of exposure.Baker et al found a relation between TWA (for B-Pb) and verbal memory and motor dexterity.4 However, TWA reflected only the previous 15 months of exposure, and was not a weighted average over the entire duration of exposure. Parkinson and colleagues used current B-Pb, TWA, peak exposure, and proportion of B-Pb values greater than 60 mg/i 00 ml as exposure indices. These authors did not find a relation between exposure variables and neuropsychological measures after adjustment for the effects of age and education.5 Hogstedt et al found differences between exposed and non-exposed controls in reaction time, learning, and memory. However, when the exposed group was analysed by TWA terciles, no significant differences (dose-effect) were found.'A recent review noted that the relation of chronic exposure and neuropsychological functioning remains unexamined.8 Our study examined the effects of chronic occupational lead exposure on neuropsychological performance. Method PARTICIPANTSWe held small group informational sessions with all employees to describe the purpose and procedure of the study. The 467 Canadian men currently and previously employed in a lead smelter (370 current, 97 former; mean (SD) age 43-4 (11-00), years of education 9 8 (3.18), years employed 17-7 (7-43)) who agreed to participate, represented about 87% of current employees. No company records were available to measure the number of former employees. Participants were not paid for their involvement, and current employees completed the evaluation at the start of their shift. A consent form explaining the purpose of the study was reviewed with each participant. Because the smelter was in a bilingual area, workers chose to be tested in either French (n = 129) or English (n = 329). Nine men chose to be evaluated with a combination of French and English. PROCEDUREThe participants completed an individual two hour neuropsychological screening battery.

No abstract

No abstract