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Dose-effect relationships between manganese exposure and neurological, neuropsychological and pulmonary function in confined space bridge welders.

Authors
Bowler-RM; Roels-HA; Nakagawa-S; Drezgic-M; Diamond-E; Park-R; Koller-W; Bowler-RP; Mergler-D; Bouchard-M; Smith-D; Gwiazda-R; Doty-RL
Source
Occup Environ Med 2007 Mar; 64(3):167-177
NIOSHTIC No.
20033383
Abstract
Background: Although adverse neuropsychological and neurological health effects are well known among workers with high manganese (Mn) exposures in mining, ore-processing and ferroalloy production, the risks among welders with lower exposures are less well understood. Methods: Confined space welding in construction of a new span of the San Francisco-Oakland Bay Bridge without adequate protection was studied using a multidisciplinary method to identify the dose-effect relationship between adverse health effects and Mn in air or whole blood. Bridge welders (n = 43) with little or no personal protection equipment and exposed to a welding fume containing Mn, were administered neurological, neuropsychological, neurophysiological and pulmonary tests. Outcome variables were analysed in relation to whole blood Mn (MnB) and a Cumulative Exposure Index (CEI) based on Mn-air, duration and type of welding. Welders performed a mean of 16.5 months of welding on the bridge, were on average 43.8 years of age and had on average 12.6 years of education. Results: The mean time weighted average of Mn-air ranged from 0.11-0.46 mg/m(3) (55% >0.20 mg/m(3)). MnB >10 microg/l was found in 43% of the workers, but the concentrations of Mn in urine, lead in blood and copper and iron in plasma were normal. Forced expiratory volume at 1s: forced vital capacity ratios (FEV(1)/FVC) were found to be abnormal in 33.3% of the welders after about 1.5 years of welding at the bridge. Mean scores of bradykinesia and Unified Parkinson Disease Rating Scale exceeded 4 and 6, respectively. Computer assisted tremor analysis system hand tremor and body sway tests, and University of Pennsylvania Smell Identification Test showed impairment in 38.5/61.5, 51.4 and 88% of the welders, respectively. Significant inverse dose-effect relationships with CEI and/or MnB were found for IQ (p
Keywords
Welders; Welding; Welding-industry; Confined-spaces; Humans; Neurological-reactions; Psychological-responses; Psychological-effects; Neurophysiological-effects; Pulmonary-function; Demographic-characteristics; Statistical-analysis; Epidemiology
Contact
Dr R M Bowler, San Francisco State University, 8371 Kent Drive, El Cerrito, CA 94530, USA
CODEN
OEMEEM
CAS No.
7439-96-5
Publication Date
20070301
Document Type
Journal Article
Email Address
rbowl@sfsu.edu
Fiscal Year
2007
NTIS Accession No.
NTIS Price
Issue of Publication
3
ISSN
1351-0711
NIOSH Division
EID
Priority Area
All Sectors
Source Name
Occupational and Environmental Medicine
State
CA; OH; NC; CO; PA
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