Radon and lung cancer:: case-control vs. ecologic studies

Problems in epidemiological studies in connection with the determination of radon-caused lung cancer are discussed. Biasing and confounding effects have led to very divergent results in epidemiological studies and there is still doubt on the carcinogenic effect of radon progenies in the concentration range of usual indoor air (say below several hundred Bq/m(3)). Nevertheless. epidemiological investigations seem to be the key tool to decide this question. Main advantages and disadvantages of case-control and ecologic studies are discussed and an overall uncertainty estimation is given for both types of investigations.