Modelling the life expectancy of rats exposed to radon

The ability of ionizing radiation to induce cancer in an irradiated organ is proven for medium and high doses beyond doubt. For radiation effects on noncancer deaths, there are conflicting claims, but at least at high doses, there is strong evidence. One approach to investigate other possible effects of radiation exposure is to study the longevity of exposed persons or animals compared to nonexposed ones. This paper uses a large data set from rats exposed to radon and radon-progeny for that purpose. The emphasis is on survival for all endpoints of death, except fatal lung cancer. For the groups exposed to a radon concentration of 10, and 100 WL, the 50% survival for “all deaths competing with fatal lung cancer” is roughly constant up to the very high exposure of 5000 WLM, while for those with 1000 WL it is also constant, but significantly lower. The data suggest that the deaths from other causes than fatal lung cancers depends mainly on the exposure rate, rather than the exposure, up to very high exposures. Exposure rates up to 100 WL tend to increase the median survival time of the exposed animals relative to the controls, while larger exposure rates decrease it. When modelling health effects from radiation, end points other than cancer should be considered too.