Mortality of workers in two Minnesota taconite mining and milling operations.

Mortality during the years 1947 to 1983 was studied in 3,444 men employed for at least 3 months in Minnesota taconite mining operations during the years 1947 to 1958. During 86,307 person-years of observation, there were 801 deaths for a standardized mortality ratio (SMR) of 88 (US white male rates) or 98 (Minnesota rates). The 41 deaths from respiratory cancer were fewer than expected, the SMR being 61 (P less than or equal to .01) (US rates) and 85 (Minnesota rates). There were 25 respiratory cancers 20 or more years after first taconite employment, for an SMR of 57 (P less than or equal to .01) (US rates). SMRs for colon cancer, kidney cancer, and lymphopoietic cancer were elevated, but below the level of statistical significance. There was one death from pleural mesothelioma, 11 years after first taconite employment, in a man with long prior employment as a locomotive operator. The pattern of deaths did not suggest asbestos-related disease in taconite miners and millers.