Objectives Exposure to excess levels of manganese in occupational settings has been associated with a neurological syndrome. So morbidity of nervous system disease among Korean workers exposed to manganese described through this large cohort study.

Method Using medical surveillance data, hospital admission of nervous system disease (GOO-G99) from 2000 to 2005 was analysed in cohort contained manganese exposed male workers (438,693 person years). Also, 2% of Korean men was randomly selected and analysed their hospital admission data. Standardised Admission Ratios (SAR) of nervous disease among manganese exposed workers was estimated reference to Korean men.

Results For 6 years, 500 admissions with nervous system diseases (G00-G99) were observed in solvents exposed workers. SARs for overall nervous diseases (G00-G09) (SAR=1.24, 95% CI 1.13–1.35), inflammatory disease of CNS (G00-G09) (SAR=1.92, 95% CI 1.52–2.39), other degenerative diseases of nervous system (G31) (SAR=3.60, 95% CI 1.16–8.40) and nerve, nerve root and plexus disorders (G50-G59) (SAR=1.66, 95% CI 1.36–2.00) were significantly higher than those of Korean men. SAR of extrapyramidal and movement disorders (G20-G26) was significantly high (SAR=2.03, 95% CI=1.05–3.55) among workers with 10 and more years employment duration.

Conclusions This manganese exposed workers’ cohort with short follow-up periods exhibits significantly elevated admission with overall and some kinds of nervous disease comparing to Korean men. Especially, increased SAR of extrapyramidal and movement disorder suggests relatedness of manganese exposure.