LUNG-CANCER AMONG TIN MINERS IN SOUTHEAST CHINA - SILICA EXPOSURE, SILICOSIS, AND CIGARETTE-SMOKING

The Dachang Tin Mine is an industrial facility with high rates of lung cancer compared to the resident population in Guangxi province in sou thern China. Historically, exposure to silica dust was very high in th e 1950s, falling in recent years to levels in keeping with internation al standards. Radon levels in the mine are low. We report the findings of a case-control study nested into a cohort study on miners working in Dachang. Cases of lung cancer among miners incident from 1973-1989 were obtained from local comprehensive medical records covering worker s employed at the mine. These were matched approximately 3 to 1 with m iners randomly chosen from the district surrounding the mine within th e same birth decade. Matched odds ratios of 2.42 (95% confidence limit [CL] 1.3, 4.4) for underground employment, 3.52 (95% CL 1.7, 7.5) for smoking, and 2.04 (95%) CL 1.2, 3.7) for silicosis as determined on c hest film were noted. Multi-factor analysis of unconditional logistic regression showed that among the risk factors for excess mortality fro m lung cancer only the years spent drilling underground and the cumula tive smoking index (product of daily cigarette consumption and number of years smoking) were independent contributors to risk and there was no interaction observed. The presence of silicosis did not contribute to predicting risk independently of the years spent underground. (C) 1 994 Wiley-Liss, Inc.