Lung cancer among underground workers in the iron ore mine of Kiruna based on thirty years of observation.

A previous study showed a three-fold increase in the risk of dying from lung cancer among underground workers in the iron ore mine in Lapland. The present report describes a follow-up covering the period 1971-1980. On the basis of data obtained in both studies an attempt is made to examine the time trend and to estimate the lifetime risk of developing lung cancer from alpha radiation from the decay of radon and its daughter products. The risk of dying from lung cancer among underground workers was seven times the corresponding risk among all other men in the community. The calculated risks for the populations working underground in 1951-1970 and 1971-1980 (ages 30-74 years) were 9.2 and 13.1 cases per 10(6) person-years and working level month respectively. The corresponding calculated risk for ages 50-64 years for 1971-1980, was 22 cases. Based on the accumulated mortality from lung cancer among mine workers exposed to radon underground in 1921-1940, the expected excess number of lung cancers in the population exposed underground in 1951-1980 is 59. So far only a total of seven cases have been observed.