Radiation protection guidelines are mainly based on studies of populations exposed to external radiation. This project regroups major European studies able to evaluate long term health effects after internal exposure to radionuclides (radon, uranium, plutonium). Large cohort and case-control studies aim to quantify the effect of multiple exposures, taking into account specific organ dose calculation, the contribution of each radionuclides and external exposure. All selected studies are characterized by precise registration of individual annual exposure:

• German, French and Czech Uranium miner cohorts, implemented during a FP5 project will inform on quantification of risk for various cancers (lung, kidney, leukaemia) and non-cancer diseases in relation to calculated organ dose by producing recent data, but also including dust and gamma exposure.

• European case-control studies on lung cancer and domestic radon give the opportunity to compare these risk estimates with those from worker studies and to calculate attributable risk for low protracted exposures to alpha particles and interactions with tobacco.

• Specific studies of nuclear workers in which doses due to internal contaminations will be reconstructed individually, especially in the UK, France and Belgium. The main interest will be on lung cancer and leukaemia risk, through nested case-control studies. Implementation of a joint French-British cohort will provide the basis for studies of long-term health effects of internal and external exposures.

Uncertainties linked to exposure estimates will be introduced into dose-risk models. Researchers in epidemiology, statistics, modelling and dosimetry will constitute a European panel supporting the data analysis and the interpretation of results.