Combined effect of silica dust exposure and tobacco smoking on the prevalence of respiratory impairments among gold miners

Scand J Work Environ Health. 1990 Dec;16(6):411-22. doi: 10.5271/sjweh.1768.


The combined effect of underground gold mining dust with a high content of free silica and tobacco smoking on the prevalence of respiratory impairment was examined among 2209 South African gold miners and 483 nonminers. The subjects were grouped as having normal function; minimal, moderate or marked obstruction; marked obstruction with restriction; or pure restriction on the basis of their lung function profiles. Each profile group was compared with the normal group for exposure prevalences, and additive and multiplicative relative risk models were applied to test for departure from the additivity of individual effects. Departure from additivity was found to increase progressively with the severity of obstructive impairment. The results indicated that approximately 94% of the cases with the most severe respiratory impairment (N = 191) could have been prevented through the elimination of tobacco smoking. In conclusion, tobacco smoking was found to potentiate the effect of dust on respiratory impairments.

MeSH terms

  • Bronchitis / etiology*
  • Forced Expiratory Flow Rates / physiology
  • Forced Expiratory Volume / physiology
  • Gold*
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Mining*
  • Regression Analysis
  • Respiratory Function Tests
  • Silicon Dioxide / adverse effects*
  • Silicosis / etiology*
  • Smoking / adverse effects*
  • Vital Capacity / physiology


  • Gold
  • Silicon Dioxide