title: Effect of lead exposure and ergonomic stressors on peripheral nerve function.
abstract: In this study we investigated the effect of recent and chronic lead exposure, and its interaction with ergonomic stressors, on peripheral nerve function. In a cross-sectional design, we used retrospective exposure data on 74 primary lead smelter workers. We measured blood and bone lead levels and, from historical records, calculated lead dose metrics reflecting cumulative lead exposure: working-lifetime integrated blood lead (IBL) and working-lifetime weighted-average blood lead (TWA). We additionally created five metrics related to IBL that cumulated exposure only above increasing blood lead levels ranging from 20 to 60 microg/dL (IBL20-IBL60). Current perception threshold (CPT) assessed large myelinated (CPT2000), small myelinated (CPT250), and unmyelinated (CPT5) sensory nerve fibers. Using multiple linear regression, we modeled CPT on the different measures of lead dose after adjusting for relevant covariates. CPT had a curvilinear relationship with TWA, with a minimum at a TWA of 28 microg/dL. Both TWA and IBL accounted for a significant percentage of the variance of CPT2000 (DeltaR2 = 8.7% and 3.9%, respectively). As the criterion blood lead level increased from IBL20 through IBL60, so did the percentage of CPT2000 variance explained, with DeltaR2 ranging from 5.8% (p < 0.03) for IBL20 to 23.3% (p < 0.00) for IBL60. IBL60 also significantly contributed to the explanation of variance of CPT250 and significantly interacted with ergonomic stressors. Measures of chronic blood lead exposure are associated with impairment of large and small myelinated sensory nerve fibers. This effect is enhanced at the highest doses by ergonomic stressors.
authors.affiliation: Center for Occupational and Environmental Neurology, Baltimore, Maryland 21211, USA. coen@msn.com
authors.forename: Margit L
authors.initials: ML
authors.lastname: Bleecker
authors.forename: D Patrick
authors.initials: DP
authors.lastname: Ford
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Vaughan
authors.forename: Karen N
authors.initials: KN
authors.lastname: Lindgren
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tiburzi
authors.forename: Karin Scheetz
authors.initials: KS
authors.lastname: Walsh
mesh_terms: D000328:Adult; D001842:Bone and Bones / Q000737:chemistry; D003430:Cross-Sectional Studies; D004558:Electric Stimulation; D006801:Humans; D007854:Lead / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009509:New Brunswick; D016273:Occupational Exposure; D010525:Peripheral Nerves / Q000187:drug effects* / Q000502:physiology; D012684:Sensory Thresholds / Q000187:drug effects; D013052:Spectrometry, X-Ray Emission
chemical_list: D007854:Lead