Radiobiological aspects of long-term epidemiological study of malignant lung neoplasm

In a 33 years' study of uranium miners with a cumulated uptake of radon daughters of 220 WLM (working level months), an incidence of malignant lung neoplasms was found exceeding almost 5 times the neoplasm rate expected for the general population. The additional annual risk of a neoplasm was 21x10-6 WLM-1 and the relative risk coefficient was 1.4% for 1 WLM. The risk level of lung neoplasms was affected by age at the time of irradiation, by the mode of dose cumulation, and to a varying extent a simultaneous inhibition (sterilization) effect of irradiation and a decrease in carcinogenic effect with the time after irradiation was seen. A lung neoplasm incidence significantly exceeding the expected one, first occurred in the 6th year after exposure to the risk had started, the maximum excess was seen in the 22nd year, and starting with year 33 the observed and expected incidences did not differ. The mean time interval between the start of exposure and death was 20.3±7.0 years. (A.K.). 6 figs., 1 tab., 21 refs