CANCER MORTALITY AMONG SILICOTICS IN CHINA METALLURGICAL INDUSTRY

Background. We conducted a retrospective cohort study of lung cancer a mong silicotics in China's metallurgical industries. The study cohort consisted of 4372 male silicotics diagnosed and alive before 1 January 1980. The follow-up period was 1 January 1980 to 31 December 1989. Re sults. Standardized mortality ratios (SMR) of all deaths, all cancers, chronic bronchopneumonia, pneumonia and pulmonary heart disease, and pulmonary tuberculosis showed statistically significant excesses. The SMR for lung cancer for the total cohort was 237 (P < 0.01). When the total study cohort was divided into various categories by occupation ( including iron ore mining, ore-sintering, refractory brick manufacturi ng, iron and steel smelting, and steel casting), significant excess lu ng cancer risk was observed among silicotics in all categories (SMR > 200, P < 0.01) except for casting (SMR = 157, P > 0.05). Excess lung c ancer was not related to years since diagnosis of silicosis or years o f exposure to silica. There was more than twofold excess lung cancer r isk among both smoking (SMR = 257, Pt 0.01) and non-smoking silicotics (SMR = 209, P < 0.01). Silicosis increased the risk of lung cancer.