Speaker
Description
For some years there has been increasing doubt about the applicability of the Linear-No-Threshold model (LNT) of radiation risk, in particular of radon risk. This concerns exposure below about 100 Bq/m³ long term, for which current epidemiological data do not seem to allow proposing a robust risk model. For exposure caused by higher concentrations, a positive, essentially linear relation seems to be assured.
The matter is relevant because the majority of the population - about 75% of Europeans - are exposed to less than 100 Bq/m³. This means that for this large fraction of citizens there is no reliable model of radon risk.
On the other hand, estimated risk is one justification of radon policy. While it is unlikely that revision of the risk model would strongly affect delineation of Radon Priority Areas, minimization of low radon exposure and certain topics of Radon Action Plans may become questionable.
In this presentation literature is quoted which is sceptical about the LNT. A number of authors are in favour of sub-linear or even hormetic models for low exposure. In any case, even if no particular model is favoured, in the absence of a reliable model one can investigate scenarios: How would Rn risk be geographically distributed, relative to the one projected by the LNT, if a different model is applied?
The overall conclusion based on scattered evidence is that the matter deserves attention and should be further studied. Large scale case control or cohort epidemiological studies are expensive, but one may re-evaluate existing data including the large amount of indoor radon measurements - more than a million in Europe - which might be used in (less reliable) ecological studies.