Several cases of
parkinsonism were found in a
ferromanganese smelter after the ventilation system had broken down and had not been repaired for eight months in 1985. To determine the aetiology and prevalence of
parkinsonism, 132 workers were submitted to thorough medical examination and estimated air concentrations of
carbon monoxide and
manganese at different worksites. Only six of eight workers performing
electrode fixation or welding during 1985 developed
parkinsonism. They were exposed for 30 minutes each day, seven days a week, to high concentrations of air
manganese (greater than 28.8 mg/m3). There was a consistent trend between the index of exposure to
manganese and signs and symptoms exhibited by extrapyramidal systems. After repair of the ventilation system, the air concentration of
manganese during
electrode fixation and welding decreased to less than 4.4 mg/m3; furthermore, no new cases of
parkinsonism have been observed. Workers with
parkinsonism recovered partially after removal from original worksites and treatment with
levodopa. It is concluded that the outbreak resulted from exposure to high concentrations of
manganese fumes through the breakdown of the ventilation system.