Estimation of the risk of radiation-induced leukaemia among young people in the vicinity of the La Hague reprocessing plant. Results from the nord-cotentin radioecological study
Rommens, C.; Laurier, D.; Merle-Szeremeta, A.; Sugier, A. ;Drombry-Ringeard, C. IRPA-10: 10. international congress of the International Radiation Protection Association Hiroshima (Japan) 14-19 May 2000
No. P-2a-106;7 refs., 4 figs., 1 tab
A radioecological study has been performed around the La-Hague nuclear reprocessing plant (Nord-Cotentin, France). The Working Group included nuclear operators, authorities, international experts and members of environmental organisations and was supported by IRSN. The study aimed to reconstruct radiation doses received by members of the public aged 0 to 24 years and living in the area, with a view to estimate the associated risk of leukaemia between 1978 and 1996. The assessment involved three steps: 1. reconstruction of a cohort of people aged 0 to 24 years, using local birth rates for the years 1954 to 1996 and taking into account the additional migrations of young people in the area. 2. estimation of doses to the red bone marrow received from all source of radiation (natural, medical, local nuclear industries and Chernobyl and weapons testing). Concentrations of radionuclides in the environment were estimated with a combination of two approaches: the modelling of the transfer of the releases in the environment and the use of environmental measurements. The dose computation takes into account the life style of the local population. ICRP dose coefficients to the red bone marrow were used. 3. derivation of leukaemia risk from a dose response model recommended by the UNSCEAR committee. The reconstructed population includes 6656 people born between 1954 and 1996, who inhabited the study area for at least one year between 1978 and 1996 before the age of 25. The number of person-years between 1978 and 1996 is 69308. The total collective dose to the red bone marrow due to local nuclear installations is 0.5 man.Sv. For the sake of comparison, the collective dose due to all sources of exposure is 241 man.Sv: The estimated number of leukaemia due to all exposure sources is 0.835. 74% are due to natural exposures, 24% to medical ones and 2% to the Chemobyl accident and nuclear arm testing. Nuclear facilities of Nord-Cotentin contribute only for 0.1% (between 0.0009 and 0.002 leukaemia for the period 1978-1996). The expectation for the number of radiation-induced leukaemia cases attributable to local nuclear installations, based on the reconstruction of exposures to ionising radiation in the Nord-Cotentin, is very low when compared to the incidence of leukaemia observed and predicted on the same period by epidemiologists (respectively 4 and 2). Two main difficulties had to be solved by the Working Group. First the retrospective character of the study resulted in a paucity of detailed information on past data. Second, the search for consensus on various hypotheses in a group composed of operators, authorities and members of environmental organisations required important efforts. On the other hand, the composition of the Working Group allowed to perform a fully contradictory assessment.