title: Mortality from nonmalignant respiratory diseases among male workers in Norwegian ferroalloy plants.
abstract: OBJECTIVE
  This study examined mortality from nonmalignant respiratory diseases among ferroalloy workers.
  
  
  METHODS
  The cohort comprised 14730 men employed for the first time in 1933-1990 and for at least 6 months in 1 of 12 plants. The duration of work in specific departments and exposure to amorphous silica in the ferrosilicon/silicon-metal (FeSi/Si-met) plants, estimated from a job-exposure matrix, were the main exposure variables. Deaths were observed during 1962-1990. The mortality was analyzed with the use of standardized mortality ratios (SMR) and internal comparisons of rates.
  
  
  RESULTS
  Overall mortality from nonmalignant respiratory diseases was not increased, but mortality from bronchitis, emphysema, and asthma combined was significantly increased among the men with at least 3 years of FeSi/Si-met furnace work (SMR 1.82, 16 deaths). A Poisson regression analysis of the mortality from these causes among 6359 employees in the FeSi/Si-met plants showed a significant increase of 0.06 per unit of amorphous silica exposure observed 10-20 years after the exposure. Six men died of pneumonia while still employed in a ferromanganese/silicomanganese (FeMn/SiMn) plant. No corresponding deaths occurred among employees in FeSi/Si-met plants. Only 2 deaths from pneumoconiosis were observed in the total cohort.
  
  
  CONCLUSIONS
  Among employees in FeSi/Si-met plants increased mortality from bronchitis, emphysema, and asthma may be associated with previous exposure to amorphous silica. Deaths from pneumonia among FeMn/SiMn workers may be associated with manganese exposure.
authors.affiliation: Telemark Central Hospital, Department of Occupational and Environmental Medicine, Skien, Norway.
authors.forename: A
authors.initials: A
authors.lastname: Hobbesland
authors.forename: H
authors.initials: H
authors.lastname: Kjuus
authors.forename: D S
authors.initials: DS
authors.lastname: Thelle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys / Q000009:adverse effects; D001991:Bronchitis / Q000209:etiology / Q000401:mortality*; D002423:Cause of Death; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D007501:Iron / Q000009:adverse effects; D058085:Iron Compounds / Q000009:adverse effects*; D008171:Lung Diseases / Q000209:etiology / Q000401:mortality*; D008345:Manganese / Q000009:adverse effects; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D009784:Occupational Diseases / Q000209:etiology / Q000401:mortality*; D016273:Occupational Exposure / Q000009:adverse effects*; D012140:Respiratory Tract Diseases / Q000209:etiology / Q000401:mortality*; D012307:Risk Factors; D017655:Silicon Compounds / Q000009:adverse effects; D012829:Silicosis / Q000209:etiology / Q000401:mortality
chemical_list: D000497:Alloys; D058085:Iron Compounds; D017655:Silicon Compounds; C083456:ferro-manganese alloy; D008345:Manganese; C027394:ferrosilicon; D007501:Iron