Mortality after long exposure to cummingtonite-grunerite

Ore containing cummingtonite-grunerite has been mined to extract gold since 1876 in Lead, South Dakota. Each of the 1,321 men who were recorded as having worked 21 years or more with the Homestake Mine was allocated to one of 5 dust-exposure categories on the basis of work history and available information on environmental conditions. All except 9 men were traced to the end of 1973, when 652 were still living; the cause of death was ascertained for 657 of the 660 men who had died. Deaths from cerebrovascular accidents and malignant disease were close to the numbers expected and from accidents and other causes were fewer than expected, but in each of the 3 diagnostic groups--pneumoconiosis (mainly silicosis), tuberculosis, and heart disease--there were more than 30 excess deaths. A clear dust-exposure relationship was found for pneumoconiosis and respiratory tuberculosis--with relative risks for the 2 groups with greatest exposure to dust as compared to the 2 with least exposure, of 19.9 and 16.0, respectively, but there was no convincing evidence of an increase in respiratory cancer.