title: Environmental exposure to manganese in air: Associations with tremor and motor function.
abstract: BACKGROUND
  Manganese (Mn) inhalation has been associated with neuropsychological and neurological sequelae in exposed workers. Few environmental epidemiologic studies have examined the potentially 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 (≥ 10 years) 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 Pegboard, 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.
  
  
  CONCLUSIONS
  Tremor and motor function were associated with higher exposure to airborne Mn.
authors.affiliation: San Francisco State University, Department of Psychology, San Francisco, CA, United States. Electronic address: rbowl@sfsu.edu.
authors.forename: Rosemarie M
authors.initials: RM
authors.lastname: Bowler
authors.affiliation: Colorado State University, Fort Collins, CO, United States.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Beseler
authors.affiliation: San Francisco State University, Department of Psychology, San Francisco, CA, United States.
authors.forename: Vihra V
authors.initials: VV
authors.lastname: Gocheva
authors.affiliation: ATSDR, Region 5, Chicago, IL, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Colledge
authors.affiliation: California School of Professional Psychology at Alliant International University, San Francisco, CA, United States.
authors.forename: Erica S
authors.initials: ES
authors.lastname: Kornblith
authors.affiliation: U.S. EPA, Region 5, Chicago, IL, United States.
authors.forename: Jaime R
authors.initials: JR
authors.lastname: Julian
authors.affiliation: Ulsan University Hospital, University of Ulsan College of Medicine, Department of Occupational and Environmental Medicine, Ulsan, South Korea.
authors.forename: Yangho
authors.initials: Y
authors.lastname: Kim
authors.affiliation: U.S. EPA, Region 5, Chicago, IL, United States.
authors.forename: George
authors.initials: G
authors.lastname: Bollweg
authors.affiliation: U.S. EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, United States.
authors.forename: Danelle T
authors.initials: DT
authors.lastname: Lobdell
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D001499:Bayes Theorem; D006801:Humans; D019570:Inhalation Exposure / Q000706:statistics & numerical data*; D008345:Manganese / Q000032:analysis*; D009483:Neuropsychological Tests; D009820:Ohio / Q000453:epidemiology; D014202:Tremor / Q000139:chemically induced / Q000453:epidemiology*
chemical_list: D000393:Air Pollutants; D008345:Manganese
keywords: Adult residents; Environment; Manganese; Neurotoxicity; Psychomotor; Tremor