| Related Wismut Studies of the BfS |
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Pooled European Study: Alpha-Risk and EUROMINERWithin the EU-alpha-risk project the French, Czech and German cohort studies on former uranium miners were investigated with respect to the cancer risk due to low radiation exposure. Moreover, organ doses for several organs and the corresponding risks were calculated. The Wismut cohort data based on the first mortality follow-up by 1998 restricted to sub-cohort B and C (begin of employment after 1954) are included in the EU-alpha risk project which ended in 2009.To actualize the pooled data and continue the successful cooperations, the EUROMINER project was initialized in the course of which it is planned to add Canadian miners cohort data to the pooling. Nested case-control study on lung cancerWith respect to lung cancer among miners, exposure to radon and its progeny is a major risk factor. However, there exist more factors, which have to be taken into account in the risk assessment. The most important factor is smoking. Furthermore there are factors like occupational exposure to other carcinogenic substances like arsenic and asbestos. Information on smoking habits and on the occupational exposure from jobs outside the Wismut are only scarcely available for the complete cohort (n=59,000 miners). For that reason, information on the lifelong smoking habits and on the exposure to occupational carcinogenic substances for jobs outside the Wismut was collected for a subset of 700 deaths from lung cancer (“cases”) and for 1,400 individuals which did not die on lung cancer (“controls”) from the Wismut cohort. The information was either obtained in interviews with the members of the study, or—in the case of death—with their relatives and, on the other hand, from investigations in the files of the former health archive of the Wismut.ResultsAs in the Wismut cohort information on smoking habits is either available only sporadically or very imprecise whence, up to now, smoking could not be taken into account in the assessment of the risk of lung cancer due to radon. However if smoking were correlated with the exposure to radon at work, then theoretically this could lead to an under- or over-estimation of the true risk of radon-induced lung cancer death. For 421 cases and 620 controls of the case-control study the smoking habits could be reconstructed. The statistical analysis of this data-basis did not differ considerably in the assessment of the lung cancer risk due to radon with and without adjustment of the smoking habits. E. g., the risk increased by 0.23% per WLM with adjustment of the smoking habits and by 0.25% without adjustment. Therefore smoking seems not to represent a major confounder for the estimation of the risk of radon induced lung cancer in the Wismut cohort. This part of the study was funded by the European Commission and has been published in "Health Physics" in 2010. Within the frame of the alpha-risk project comparable case-control studies were perfomed in France and Czechia and the data were analyzed jointly with the German ones. The results of the pooled European case-cohort studies were published the journal “Radiation Research” in 2011.Nested case-control study on leukaemiaDue to their high reproductive rate cells of the haematopoietic system are especially susceptible to radiation induced mutation. Hence an increase in the leukaemia rate was also one of the first non-deterministic radiation damages that were observed in survivors of the atomic bombings in Hiroshima and Nagasaki. On the other hand only few miner cohorts found an increased rate of leukaemia. There are, inter alia, methodological reasons for this: On one hand the radiation dose to the red bone marrow is about one hundred times smaller than e.g. the lung dose. On the other hand the number of spontaneous leukaemia cases is small even in larger studies. Within the German cohort 168 leukaemia deaths were observed in the third follow up. The red bone marrow dose is due to a considerable extent also to medical examinations which were performed in the frame of programs for the early detection of tuberculosis and silicosis. Therefore data on X-ray examinations are currently extracted from the Wismut medical data archive for the 168 leukaemia deaths and thrice the number of controls with the view to determine the leukaemia risk due to radiation. The data are being collected on behalf of the BfS by the German federal institute for occupational safety and health (BAuA).Study on offsprings of Wismut workersThe question of whether a high radiation exposure of the fathers may result in health damages in the offspring is a point of controversial scientific discussion. A Canadian study gives weak indications for an increased risk of leukemia for children of uranium miners. To address the question of possible genetic effects, the BfS conducted a feasibility study for a cohort study with about 7,000 children of uranium miners. However, a first analysis of the data did show a series of methodological problems, which would strongly reduce the significance of the study. This includes a high percentage of missing causes of death for the deceased offspring, especially for years of death between 1950 and 1970, a non negligible fraction of children which could not be located and a relatively low exposure of the gonads of the employees of the Wismut before the conception of the children. Due to these methodological problems it was decided not to carry out the main cohort study. |