title: Relation of cumulative exposure to inorganic lead and neuropsychological test performance.
abstract: OBJECTIVE
  To determine if measures reflecting chronic occupational lead exposure are associated with performance on neuropsychological tests.
  
  
  METHODS
  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) micrograms dl-1) 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) micrograms dl-1, mean IBL 765.2 (0.6-1625.7) micrograms-y dl-1). 14 neuropsychological variables were included in three multivariate analyses of covariance, with each exposure variable as the grouping variable (high, medium, and low) and age, education, score on a measure of depressive symptoms, and self reported alcohol use as the covariates. Groups did not differ in history of neurological conditions.
  
  
  RESULTS
  Neither the B-Pb, TWA, nor IBL was significant by multivariate analyses of covariance (MANCOVA). When years of employment, a suppressor variable, was included as a covariate, IBL exposure groups differed significantly on digit symbol, logical memory, Purdue dominant hand, and trails A and B.
  
  
  CONCLUSIONS
  A dose-effect relation was found between cumulative exposure (IBL) and neuropsychological performance at a time when current B-Pb concentrations were low and showed no association with performance.
authors.affiliation: Center for Occupational and Environmental Neurology, Baltimore, MD 21211, USA.
authors.forename: K N
authors.initials: KN
authors.lastname: Lindgren
authors.forename: V L
authors.initials: VL
authors.lastname: Masten
authors.forename: D P
authors.initials: DP
authors.lastname: Ford
authors.forename: M L
authors.initials: ML
authors.lastname: Bleecker
mesh_terms: D000328:Adult; D015986:Confounding Factors, Epidemiologic; D004651:Employment; D006801:Humans; D007854:Lead / Q000009:adverse effects* / Q000097:blood; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D016273:Occupational Exposure / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D007854:Lead