End-stage renal disease among silica-exposed gold miners - A new method for assessing incidence among epidemiologic cohorts

Objective.-To examine the association between silica exposure and end-stage renal disease (ESRD). Design.-Retrospective cohort study. Participants.-A cohort of 2412 white male gold miners was studied. Eligible gold miners worked underground for at least 1 year between 1940 and 1965 in a South Dakota gold mine and were alive on January 1, 1977. Of primary interest was exposure to silica. Methods.-The ESRD Program Management and Medical Information System (PMMIS) was used to identify members of the gold mine cohort who had treated ESRD and to create a US rate file for treated ESRD. The ESRD incidence among the gold miners was compared with that in the US population. Results.-Based on the 11 cohort members identified with treated ESRD, the risk for ESRD in the cohort was elevated (standardized incidence ratio [SIR], 1.37; 95% confidence interval [CI], 0.68-2.46). The risk was greatest for nonsystemic ESRD (ESRD caused by glomerulonephritis or interstitial nephritis) for which the SIR was 4.22 (95% CI, 1.54-9.19), increasing to 7.70 (95% CI, 1.59-22.48) among workers with 10 or more years of employment underground. Conclusions.-To our knowledge this is the first epidemiologic study to examine ESRD incidence in an occupational cohort. This study provides evidence that silica exposure is associated with an increased risk for ESRD, especially ESRD caused by glomerulonephritis. This study also demonstrates the usefulness of the ESRD PMMIS to assess ESRD risk among cohorts exposed to potential nephrotoxins.