[en] Indoor radon concentrations are subject to seasonal variation with a maximum in winter and a minimum in summer. Procedures to correct for seasonal variation are necessary in order to get an unbiased estimate of the annual average radon concentration from data based on short-period radon measurements. To obtain correction factors, we apply the model developed by Pinel et al to the French database of indoor radon measurements (measurements performed as part of the indoor radon case control study and of the national radon measurement campaign). For 6-month measurements, the correction factors vary from 0.87 to 1.17 and agree with those previously published. These results might be applicable when assessing indoor radon concentrations with regard to recommended action levels. (author)

[en] An increased lung cancer risk associated with radon exposure has been reported both in underground miner cohort studies and in animal experiments. However a large proportion of these results came from populations who received high radon exposure for a short period of time. Our aim is to analyse the effects of radon in populations exposed to low level and low rates over long periods. In France, research was developed in parallel both in the field of epidemiology through the cohort of uranium miners, and in that of animal experiments. We present here recent results underlying the points of agreement between epidemiological and experimental approaches. The French cohort of uranium miners includes 5098 miners with low cumulative radon exposure protracted over a long duration. Results show a significant increase of lung cancer risk with cumulative exposure to radon. Period of exposure appears as an important modifier of the exposure-risk relationship (reflecting historical changes in radiation protection and measurement methods), but no effect of exposure rate is observed. Recent animal experiment were conducted in France by CEA and Cogema at low levels of exposure. More than 4600 rats have been exposed to various exposure rates and durations under controlled conditions, and followed-up over their life span. Results show that the risk increases with cumulative exposure. In this experiments, an inverse exposure rate effect is observed at the highest level of exposure. Such effect is not observed at the lowest level. Epidemiological and animal data are consistent to show an increase of risk with cumulative exposure protected at low exposure rates. Animal data are also consistent with previous studies of underground uranium miners showing an inverse exposure rate effect at high level, but this effect disappears at low levels of exposure. (Author) 20 refs

[en] Radon is a natural radioactive gas that tends to accumulate in indoor environments; its concentration is highest in areas with granite sub-soils. Epidemiologic studies of uranium miners and animal data demonstrate the radon inhalation increases the risk of lung cancer. The objective of this paper is to present the available data on the French population's exposure to radon and the current epidemiologic knowledge of its effects, from cohort studies of uranium miners and indoor radon case-control studies

[en] Seven articles constitute this chapter about environment. Natural radioactivity, table water analysis, cosmic radiation on board a plane, evaluation of radiation doses in the case of tritium releases, knowledge got from the radioecology group of North Cotentin are the different subject studied in this file. (N.C.)

[en] The authors report an investigation which aims at the identification of clayey minerals in the sedimentary series of the Tim Mersoi basin in Niger, and of their petrogenetic meaning. Based on spectrometry and on chemical micro-analysis, they identify the different components of the Tosudite present in the clayey phase: a sodoite-type chlorite and a montmorillonite-type smectite. The presence of Tosudite is interpreted as the result of a post-diagenetic episode related to infiltrations of magnesium-based and oxidative solutions. The way the uranium-bearing minerals precipitated suggests that the Tosudite is a marker of a mineralisation episode

[en] Introduction: A nested case-control study was conducted among the French uranium miners cohort in order to assess the effect of protract ed radon exposure on lung cancer risk taking into account tobacco consumption. Material and methods: One hundred uranium miners employed by the French company CEA-COGEMA and who died of a lung cancer between 1980 and 1994 were identified as cases among the cohort. For each case, five controls were randomly matched on birth period and attained age at the time of death of the corresponding case. Cumulated radon exposure during employment was reconstructed for each of these 100 cases and 500 controls. Smoking habits were retrospectively determined from three complementary sources: 1) medical files, 2) forms filled in by occupational physicians and 3) questionnaires applied in face-to-face interviews, phone calls or mailings. Analysis was performed by conditional logistic regression using a linear excess relative risk (ERR) model. A multiplicative model was fitted to assess the joint effect of radon exposure and smoking on lung cancer risk. Results: Smoking status was established for 62 cases and 320 controls and two categories ('ever smokers' vs. 'never smokers') were defined. Ninety percent of the cases and 73% of the controls were classified as 'ever smokers'. Mean five-year lagged cumulated radon exposures were 82.0 and 47.6 working level months (WLM) for the cases and the controls, respectively. The excess relative risk per WLM (ERR/WLM) was 1.1% with a 95%-confidence interval (CI) of 0.2-2.0%. When adjusting for smoking, radon exposure effect was little modified (ERR/WLM = 0.8%, 95% -CI = 0.1- 2.8%). The effect of smoking on lung cancer risk was comparable to results reported in previous miners cohorts (OR = 3.04, 95% -CI = 1.20-7.70). Discussion: A consequent effort was carried out to collect smoking status from three sources for the miners included in this nested case-control study. This analysis shows that, when adjusting on tobacco effect, the estimated lung cancer risk coefficient obtained for radon exposure is close to that obtained from the French miners cohort and coherent with results from other miners cohorts. As the information came from three different sources, complementary analyses are necessary to investigate a possible induced bias. Nevertheless, some limiting features of the study have to be underlined: the categorization of smoking status in only two levels, the moderate percentage of missing data and the low number of never smoker cases (only 6 never smokers among cases), which limit the statistical power of further analyses. In the framework of a European project on the quantification of risks associated with multiple radiation exposures named Alpha-Risk, a collaborative work including these data and large data sets from German and Czech partners should allow a more powerful analysis of radon exposure and tobacco consumption effects on lung cancer risk among uranium miners. (authors)

[en] Indoor radon concentrations are subject to seasonal variation with a maximum in winter and a minimum in summer. Due to the constraints of time placed on an epidemiological study, it is not always possible to perform radon measurements over one year, and thus there is a need for seasonal correction in order to make measurements comparable with each other and to calculate annual concentrations. In France, a national radon campaign has been carried out since 1982. Besides, a series of measurements have been made as part of an indoor radon case-control study carried out in 5 regions (Auvergne, Ardennes, Brittany, Languedoc, Limousin). With all these data, seasonal correction factors have been estimated using the methodology of Pinel et al. In this paper the derivation of these correction factors is described and they are compared with existing factors published elsewhere

[en] Radon is a naturally occurring radioactive gas which concentrates in deficiently ventilated habitations. Radon is a well-established human pulmonary carcinogen agent. The exposition of the overall French population to various radon concentrations led scientists to assess its public health impact. This study proposes a predictive assessment of health impact attributable to indoor radon exposure in metropolitan France. Using all available data on the exposure-response between radon exposure and lung cancer mortality risk and on the assessment of indoor radon exposure in France, this study is based on quantitative safety risk assessment method associated to an analysis of both variability and uncertainty, which allows to measure an uncertainty interval related to the prediction. The estimated annual number of lung cancer deaths attributable to indoor radon exposure ranges from 1 234 (90% uncertainty interval, 593-2 156) to 2 913 (90% UI, 2 763-3 221), depending on the model considered. This result shows that indoor radon exposure is a serious public health problem in France. (author)

[en] Exposure of the French population to ionising radiation is mainly due to natural radiation (i.e. exposure through: inhalation of radon decay products, external radiation of terrestrial and cosmic origin and water and food ingestion). In an epidemiological context, it is necessary to estimate as precisely as possible the population exposure, in order to study its influence on health indicators. In this aim, indicators of population exposure should be created taking into account results of environmental measurements by controlling the different factors that may influence these measurements (dwelling characteristics, seasonal variations, population density). The distribution of these exposures should also be studied at different geographical levels (department, job area). This work updates the estimation of the French population exposure to natural radiation. Radon exposure indicators have been based on concentrations measured in dwellings, corrected on season and dwelling characteristics (departmental range: 19-297 Bq/m³). Indicators of terrestrial gamma ray exposure have been based on measured indoor and outdoor dose rates adjusted on dwelling characteristics (22-95 nSv/h). Cosmic ray exposure has been evaluated from altitude and weighted by population density (0.27-0.38 mSv/yr). Due to these three components, the effective annual dose was estimated to be at 2.2 mSv. (author)

[en] The characterization and the localization of surface contamination is of first importance during the decommissioning process of a nuclear facility. Yet, there is currently no device capable of giving a real-time image of the surface contamination by α or β emitters. The MAUD project (supported by the French National Radioactive Waste Management Agency ANDRA) aims at developing a new type of portable detector capable of reconstructing the radioactivity image on a solid surface in real-time, and to provide an accurate mapping of contamination at the scale of a facility. The radiation detection principle is based on the scintillation process of a solid material. The light emitted by the latter is detected using a Silicon Photomultiplier (SiPM) array in direct contact with the scintillator. The SiPM analogic output is digitalized by a data acquisition system, which is directly connected to a computer in order to perform data processing and display the measurement result. The preliminary results obtained in laboratory are very promising and an industrial prototype should be tested in a dismantling facility early 2019.