Mortality among different occupational groups of workers with pneumoconiosis: results from a register-based cohort study.

A mortality cohort study was carried out on 11,224 men with pneumoconiosis diagnosed during the period 1970-1985. The cohort was selected from among subjects entered into the National Register of Occupational Diseases and included 7,065 coal miners, 924 employees of underground work enterprises, 1,796 workers of the metallurgical industry and iron and nonferrous foundries, as well as 1,439 refractory materials, china, ceramics, and quarry workers. The cohort was traced up to the end of 1991. The mortality of all groups enrolled in the study, as compared with that of general male population of Poland, showed a statistically significant excess of overall mortality (SMRs ranging from 105; 95% confidence interval [CI]: 100-110 to 136; CI: 121-153) as well as a great excess of deaths from diseases of the respiratory system (SMRs from 383; 95% CI: 345-424 to 588; 95% CI: 457-744). In workers of the metallurgical industry, foundries, and those from refractory materials, china, and ceramics manufacturing plants as well as quarries, a statistically significant excess of deaths from infectious diseases (mostly tuberculosis) was found (SMRs: 503; 95% CI: 364-677 and 286; 95% CI: 177-437, respectively). Mortality from lung cancer was significantly elevated only in the group of metallurgical industry and iron and nonferrous foundry workers (SMR: 159; 95% CI: 124-201). In the remaining subcohorts, no significant excess of deaths from lung cancer was noted. The study does not support the hypothesis on the role of exposure to crystalline silica in the induction of lung cancer. Significantly lower mortality was seen for diseases of the circulatory system (SMR: 89; 95% CI: 82-96), hypertensive disease (SMR: 63; 95% CI: 38-98), cerebrovascular disease (SMR: 79; 95% CI: 62-99), atherosclerosis (SMR: 79; 95% CI: 66-93), and injuries and poisonings (SMR: 50; 95% CI: 38-64) in coal miners. In addition, lower mortality was noted for cerebrovascular disease (SMR: 56; 95% CI: 32-91) and injuries and poisonings (SMR: 34; 95% CI: 17-61) in metallurgical industry and iron and nonferrous foundry workers.