Risk assessment for indoor exposure to radon daughters.

Approaches to and results for the estimation of healths risks from indoor exposure to radon and its daughter products are discussed. Particular weight is given to the derivation of exposure-time-effect relationships using a modified proportional hazard model which has been adapted to account for relevant epidemiological data. The results of this analysis indicate that about (10 +/- 5) % of the lung cancer rate observed in the general public might be correlated to the enhanced exposure to radon daughters in dwellings (at 10 - 20 Bq/m3 (Rn-eq] and in outdoor air. A chronic exposure to indoor Rn-levels at home of about 300 - 500 Bq/m3 (Rn-eq) might possibly double the normal lung cancer rates. The relative fractions of radiogenic lung cancer rates might be nearly the same for smokers and non-smokers, and for men and women.