Cancer in man after exposure to Rn daughters.

Results are reported of epidemiological studies in six groups of miners, who work in U mines, Fe mines and shale clay mines. A significant excess of lung cancer was proved in exposure categories below 50 WLM, the first significant excess of lung cancer rate was found in the sixth year following the start of exposure, and a significant difference between the observed and expected rate was found in miners even before the fortieth year of age. The mean attributable annual cancer risk after about 30 y of observation in the whole study was approximately 20.0 and in persons starting exposure after 30 y of age the risk was approximately 30.0 per year per 1 WLM per 10(6) persons. The dose-effect relationship and the attributable lung cancer risk per 1 WLM were significantly influenced by the age at the first exposure by total accumulated exposure and by the character of the accumulation of exposure. The observed effects of smoking and exposure to alpha radiation from Rn daughters were nearly additive. The lung cancer risk per 1 WLM at low levels of exposure (not including the contribution from natural sources in the living environment) in U as well as Fe mines indicated a certain elevation compared with the risk at higher accumulated exposure.