title: A large, nationwide, longitudinal study of central nervous system diseases among Korean workers exposed to manganese.
abstract: BACKGROUND
  In occupational epidemiologic studies, the low incidence and chronic process of central nervous system (CNS) diseases has complicated the determination of the relationship between increased morbidity and manganese (Mn) exposure. Therefore, through this large cohort study, we evaluated CNS disease morbidity among Korean workers exposed to Mn
  
  
  METHODS
  Data were collected from Mn-associated specialized medical check-up 2000 and 2004 in Korea. The number of workers admitted to hospital because of clinically diagnosed CNS disease was analyzed in male workers exposed to Mn (n = 104,544). As a control reference population, 2% of Korean men were randomly selected and their hospital admission data were analyzed. For Mn-exposed workers, Standardized admission ratios (SARs) for CNS disease, as determined by ICD-10 classifications, were estimated in reference to the control population
  
  
  RESULTS
  During follow up, 64 workers admitted because of CNS diseases. Chronic exposure to Mn (≥ 10 years) was significantly associated with the SAR (95% CI) of extrapyramidal and movement disorders (SAR: 2.03, 95% CI: 1.05-3.55), in particular, other extrapyramidal and movement disorders (SAR: 4.81, 95% CI: 1.29-12.32). Also borderline association (SAR = 4.88, 90% CI: 1.05-7.04) was noted for secondary Parkinsonism among workers with chronic Mn exposure. SARs (95% CI) for other degenerative nervous system diseases were significantly higher in Mn-exposed workers compared with the control population (SAR: 3.60, 95% CI: 1.16-8.40) CONCLUSION: In conclusion, Mn-exposed workers exhibited significantly elevated SARs for degenerative nervous system diseases and extrapyramidal and movement disorders, compared to the age-matched reference population, suggesting a relatedness with Mn exposure.
authors.affiliation: The Institute for Occupational Health, Yonsei University College of Medicine, Seoul, Republic of Korea; Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jin-Ha
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Occupational and Environmental Medicine, Dongguk University Ilsan Hospital, Ilsan, Goyang, Gyeonggi-do, 410-773, Republic of Korea. Electronic address: ysahn@dongguk.ac.kr.
authors.forename: Yeon-Soon
authors.initials: YS
authors.lastname: Ahn
mesh_terms: D000328:Adult; D017677:Age Distribution; D002493:Central Nervous System Diseases / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020149:Manganese Poisoning / Q000150:complications* / Q000453:epidemiology*; D008875:Middle Aged; D009069:Movement Disorders / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D056910:Republic of Korea / Q000453:epidemiology; D055815:Young Adult
keywords: Central nervous system diseases; Degenerative nervous system diseases; Manganese; Occupational epidemiology; Parkinsonism