Quantitative relationship between silica exposure and lung cancer mortality in German uranium miners, 1946-2003

Br J Cancer. 2012 Sep 25;107(7):1188-94. doi: 10.1038/bjc.2012.374. Epub 2012 Aug 28.


Background: In 1996 and 2009, the International Agency for Research on Cancer classified silica as carcinogenic to humans. The exposure-response relationship between silica and lung cancer risk, however, is still debated. Data from the German uranium miner cohort study were used to further investigate this relationship.

Methods: The cohort includes 58677 workers with individual information on occupational exposure to crystalline silica in mg m(-3)-years and the potential confounders radon and arsenic based on a detailed job-exposure matrix. In the follow-up period 1946-2003, 2995 miners died from lung cancer. Internal Poisson regression with stratification by age and calendar year was used to estimate the excess relative risk (ERR) per dust-year. Several models including linear, linear quadratic and spline functions were applied. Detailed adjustment for cumulative radon and arsenic exposure was performed.

Results: A piecewise linear spline function with a knot at 10 mg m(-3)-years provided the best model fit. After full adjustment for radon and arsenic no increase in risk <10 mg m(-3)-years was observed. Fixing the parameter estimate of the ERR in this range at 0 provided the best model fit with an ERR of 0.061 (95% confidence interval: 0.039, 0.083) >10 mg m(-3)-years.

Conclusion: The study confirms a positive exposure-response relationship between silica and lung cancer, particularly for high exposures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arsenic Poisoning
  • Cohort Studies
  • Follow-Up Studies
  • Germany / epidemiology
  • Humans
  • Lung Neoplasms / mortality*
  • Male
  • Mining / statistics & numerical data*
  • Neoplasms, Radiation-Induced / mortality*
  • Occupational Diseases / mortality*
  • Occupational Exposure / adverse effects
  • Occupational Exposure / statistics & numerical data*
  • Radon / poisoning
  • Risk Factors
  • Silicon Dioxide / poisoning*
  • Uranium / poisoning*


  • Uranium
  • Silicon Dioxide
  • Radon