Silicosis among gold miners: exposure--response analyses and risk assessment

Am J Public Health. 1995 Oct;85(10):1372-7. doi: 10.2105/ajph.85.10.1372.


Objectives: This study sought to estimate the risk of silicosis by cumulative exposure-years in a cohort of miners exposed to silica, as well as the lifetime risk of silicosis under the current Occupational Safety and Health Administration (OSHA) standard (0.09 mg/m3).

Methods: In a cohort study of 3330 gold miners who worked at least 1 year underground from 1940 to 1965 (average 9 years) and were exposed to a median silica level of 0.05 mg/m3 (0.15 mg/m3 for those hired before 1930), 170 cases of silicosis were determined from either death certificates or two cross-sectional radiographic surveys.

Results: The risk of silicosis was less than 1% with a cumulative exposure under 0.5 mg/m3-years, increasing to 68% to 84% for the highest cumulative exposure category of more than 4 mg/m3-years. Cumulative exposure was the best predictor of disease, followed by duration of exposure and average exposure. After adjustment for competing risks of death, a 45-year exposure under the current OSHA standard would lead to a lifetime risk of silicosis of 35% to 47%.

Conclusions: Almost 2 million US workers are currently exposed to silica. Our results add to a small but increasing body of literature that suggests that the current OSHA silica exposure level is unacceptably high.

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Cohort Studies
  • Cross-Sectional Studies
  • Gold*
  • Humans
  • Male
  • Maximum Allowable Concentration
  • Middle Aged
  • Mining*
  • Occupational Exposure*
  • Population Surveillance
  • Radiography
  • Risk Assessment
  • Risk Factors
  • Silicosis / diagnostic imaging
  • Silicosis / epidemiology*
  • Silicosis / etiology
  • South Dakota / epidemiology
  • United States
  • United States Occupational Safety and Health Administration


  • Gold