Is There an Increased Risk of Lung Cancer among the Chinese Silica Cohort? - The Influence of Occupational Confounders

To evaluate a possible influence of confounding in risk estimation for lung cancer in relation to silica dust exposure, we re-analyze a recently published exposure-response relationship using a sub-cohort of Chinese tungsten miners which has no relevant occupational confounders. The cohort of tungsten miners consisted of 19,007 workers in six tungsten mines with a follow-up period from January 1, 1960 to December 31, 2003. Cumulative silica dust exposure was estimated by linking the work history to the job-exposure matrix. The time-dependent Cox proportional hazards model was used for exposure-response analysis. Analysis of the cohort of tungsten miners does not deliver a clear exposure-response relationship between silica dust exposure and lung cancer deaths. The Chinese silica cohort fails as yet to provide clear evidence of a dose-response relationship between silica dust exposure and lung cancer risk in the absence of occupational confounding factors.