The mortality experience of a large cohort of Homestake Gold Mine (South Dakota) employees was investigated for possible connections between cummingtonite (12419475) grunerite (14567614), an amphibole mineral present in the mine, and the occurence of cancer in general and lung cancer in particular in these employees. A total of 3,144 males, employed full time underground for one or more years between January 1904 and December of 1964, were included in this study. Of the 3,144, 2,137 were alive at the closing date (June 1977), 827 were known dead (death certificates available for 733) and 180 could not be located. The data indicated that cohort members were at high risk of death from respiratory and nonrespiratory tuberculosis, certain nonmalignant respiratory diseases, and accidents. Many of those with nonmalignant respiratory diseases have pathologically confirmed silicosis. The authors conclude that the increased risk of death from this cause is largely explained by silicosis. Listed under other causes of death is leukemia, and there is a high mortality ratio here based on nine observed deaths with the risk confined to those with over 10 years in employment underground. It is suggested that a case control study be conducted for leukemia in this cohort. None of the findings indicate that risk of lung cancer is related to underground employment at this mine.
Industry-Wide Studies Branch, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio