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Environmental Exposure to Manganese in Air: Associations with Tremor and Motor Function
Citation:
Bowler, R., C. Beseler, V. Gocheva, M. Colledge, E. Kornblith, J. Julian, Y. Kim, G. Bollweg, AND D. Lobdell. Environmental Exposure to Manganese in Air: Associations with Tremor and Motor Function. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 541:646-654, (2015).
Impact/Purpose:
This study addresses research questions under Sustainable and Healthy Communities (2.2.1.6 lessons learned, best practices and stakeholder feedback from community and tribal participative case studies). This Regional Applied Research Effort project is a joint effort between Region 5 and ORD Scientists that examined neurotoxic effects of Mn within two communities: a high level air exposure community (East Liverpool, Ohio) and a mid to low range air exposure community (Marietta, Ohio). This work is important in that either positive results (differences between the high level air Mn exposure community and comparison communities) or negative results (little or no differences among communities) inform the issue of potential health effects of residential airborne Mn exposure, a recognized gap in Mn health effects literature. Both outcomes can also help inform the need for greater airborne Mn control.
Description:
BACKGROUND: Manganese (Mn) inhalation has been associated with neuropsychological and neurological sequelae in exposed workers. Few environmental epidemiologic studies have examined the potentialy neurotoxic effects of Mn exposure in ambient air on motor function and hand tremor in adult community residents. Mn exposed residents were recruited in two Ohio towns: Marietta, a town near a ferro-manganese smelter, and East Liverpool, a town adjacent to a facility processing, crushing, screening, and packaging Mn products.METHODS: Chronic (≥10years) exposure to ambient air Mn in adult residents and effects on neuropsychological and neurological outcomes were investigated. Participants from Marietta (n=100) and East Liverpool (n=86) were combined for analyses. AERMOD dispersion modeling of fixed-site outdoor air monitoring data estimated Mn inhalation over a ten year period. Adult Mn exposed residents' psychomotor ability was assessed using Finger Tapping, Hand Dynamometer, Grooved Pegbcard, and the Computerized Adaptive Testing System (CATSYS) Tremor system.Bayesian structural equation modeling was used to assess associations between air-Mn and motor function and tremor .RESULTS: Air-Mn exposure was significantly correlated in bivariate analyses with the tremor test (CATSYS) for intensity, center frequency and harmonic index. The Bayesian path analysis model showed associations of air-Mn with the CATSYS non-dominant center frequency and harmonic index;while the Bayesian structural equation model revealed associations between air Mn and lower Finger Tapping scores. Household income was significantly associated with motor dysfunction but not with tremor.CONCLUSION: Tremor and motor function were associated with higher exposure to airborne Mn.
