Non-fibrous mineral dusts and malignant tumors: an epidemiological study of mortality.

The connection between enhanced oncological risk and the exposure to non-fibrous mineral dusts receives a contradictory but mostly negative estimation in the literature. The present authors estimated the death rate by relating the number of deaths from cancer, registered at different companies during a 21 to 27-year span, to the number of man-years of work for all employees during the same period. The death rates, calculated as above, were compared with the age standardized analogous death rates of the control population. The ratio of these indices, which statistically significantly exceeded 1.0, was taken as evidence of risk connected with exposure to the industrial environment. Frequency of registration of deaths from malignant tumors among other causes of death of silicotic patients was also studied. The results are in favor of accepting talc dust (even that not containing fibrous minerals) as a carcinogen, and silica containing dust only as a cocarcinogenic agent. The percent silica content in dust either plays no role at all, or plays a much lesser role than the total dust load. Tbc as the competing cause of death in silicotic patients, in grave forms of the disease, eliminates the susceptibility of patients to death from cancer.