[Indoor radon exposure and lung cancer risk. Results of an epidemiological study carried out in France]. / Exposition domestique au radon et risque de cancer du poumon.

INTRODUCTION: Several epidemiological studies have indicated an increased risk of lung cancer associated with indoor radon exposure. As part of a large European project, a hospital based case-control study was carried out in four regions of France: Auvergne, Brittany, Languedoc-Roussillon and Limousin. MATERIAL AND METHODS: Individual data on demographic characteristics, residential history, smoking and occupational exposures were collected during face-to-face interviews. Radon concentrations were measured in each dwelling occupied by the subject during the 30-year period prior to the interview. RESULTS: 486 cases and 984 controls were included in the study. After adjustment for age, sex, region, smoking history and occupational exposure, the risk of lung cancer increased by 4% per 100 Bq/m(3), when considering cumulative exposure in the 30 years prior to diagnosis. CONCLUSION: The study indicates a positive association between lung cancer risk and indoor radon exposure. The risk estimate per unit of exposure is in agreement with other recently published indoor case-control studies.

Uncertainty analysis of the weighted equivalent lung dose per unit exposure to radon progeny in the home.

A parameter uncertainty analysis has been performed to derive the probability distribution of the weighted equivalent dose to lung for an adult (w(lung) H(lung)) per unit exposure to radon progeny in the home. The analysis was performed using the ICRP Publication 66 human respiratory tract model (HRTM) with tissue weighting factor for the lung, w(lung) = 0.12 and the radiation weighting factor for alpha particles, wR = 20. It is assumed that the HRTM is a realistic representation of the physical and biological processes, and that the parameter values are uncertain. The parameter probability distributions used in the analysis were based on a combination of experimental results and expert judgement from several prominent European scientists. The assignment of the probability distributions describing the uncertainty in the values of the assigned fractions (ABB, Abb, AAI) of the tissue weighting factor proved difficult in practice due to lack of quantitative data. Because of this several distributions were considered. The results of the analysis give a mean value of w(lung) H(lung) per unit exposure to radon progeny in the home of 15 mSv per working level month (WLM) for a population. For a given radon gas concentration, the mean value of w(lung) H(lung) per unit exposure is 13 mSv per 200 Bq.m(-3).y of 222Rn. Parameters characterising the distributions of w(lung) H(lung) per unit exposure are given. If the ICRP weighting factors are fixed at their default values (ABB, Abb, AAI = 0.333, 0.333, 0.333; w(lung) = 0.12; and wr = 20) then on the basis of this uncertainty analysis it is extremely unlikely (P approximately 0.0007) that a value of Hw/Pp for exposure in the home is as low as 4 mSv per WLM, the value determined with the epidemiological approach. Even when the uncertainties in the ABB, Abb, AAI, values are included then this probability is predicted to be between 0.01 to 0.08 depending upon the distribution assumed for describing the uncertainties in the ABB, Abb, AAI, values. Thus, it is concluded that the uncertainties in the HRTM parameters considered in this study cannot totally account for the discrepancy between the dosimetric and epidemiological approaches.

Study of a predictive methodology for quantification and mapping of the radon-222 exhalation rate.

We propose a new methodology for predicting areas with a strong potential for radon (222Rn) exhalation at the soil surface. This methodology is based on the Rn exhalation rate quantification, starting from a precise characterisation of the main local geological and pedological parameters that control the radon source and its transport to the soil/atmosphere interface. It combines a cross mapping analysis of these parameters into a geographic information system with a model of the Rn vertical transport by diffusion in the soil. The rock and soil chemical and physical properties define the entry parameters of this code (named TRACHGEO) which calculates the radon flux density at the surface. This methodology is validated from in situ measurements of radon levels at the soil/atmosphere interface and in dwellings. We apply this approach to an area located in western France and characterised by a basement displaying a heterogeneous radon source potential, as previously demonstrated by lelsch et al. (J. Environ. Radioactivity 53(1) (2001) 75). The new results obtained show that spatial heterogeneity of pedological characteristics in addition to basement geochemistry--must be taken into account to improve the mapping resolution. The TRACHGEO forecasts explain the Rn exhalation variability on a larger scale and in general correlate well with in situ observations. Moreover, the radon-prone sectors identified by this approach generally correspond to the location of the dwellings showing the highest radon concentrations.

Aerosolization of cationic lipid-DNA complexes: lipoplex characterization and optimization of aerosol delivery conditions.

This study deals with the development of gene therapy in the treatment of lung diseases. It reports on the use of ultrasonic nebulization to administer plasmid-lipid complexes to the lungs of mice to transfect their epithelial cells. A plasmid complexed to cationic lipids was aerosolized using an ultrasonic nebulizer. We then characterized the lipoplex size and visualized the lipoplex by electron microscopy. Finally, we assessed the in vivo transgene expression in the lungs further to the aerosolization of different lipid-plasmid formulations. The nebulizer-generated particles were small and looked like a string composed of little and more or less cubic units. Transgene expression was detected in the lungs of mice further to a 20-min exposure to aerosol particles produced with the ultrasonic nebulizer. The results obtained with our optimized plasmid-lipid-NaCl formulation suggest that this route can be used to administer an appropriate gene to the airways for the treatment of respiratory disorders.

Size distribution, equilibrium ratio and unattached fraction of radon decay products under typical indoor domestic conditions.

In order to characterise the behaviour of radon decay products under domestic conditions, long-term measurements were carried out from May 1997 to April 1998 in a typical dwelling located in Brittany (France). In particular, the unattached fraction and equilibrium factor were continuously measured. Moreover, the size distributions of unattached and attached radon daughters were investigated by using specific instruments implemented in the laboratory. All these experiments were carried out under different typical aerosol conditions. The results evidenced the strong influence exerted by the characteristics (concentration, size) of ambient aerosol on these different parameters.

Radon (222Rn) level variations on a regional scale: influence of the basement trace element (U, Th) geochemistry on radon exhalation rates.

The approach proposed in this study provides insight into the influence of the basement geochemistry on the spatial distribution of radon (222Rn) levels both at the soil/atmosphere interface and in the atmosphere. We combine different types of in situ radon measurements and a geochemical classification of the lithologies, based on 1/50,000 geological maps, and on their trace element (U, Th) contents. The advantages of this approach are validated by a survey of a stable basement area of Hercynian age, located in South Brittany (western France) and characterized by metamorphic rocks and granitoids displaying a wide range of uranium contents. The radon source-term of the lithologies, their uranium content, is most likely to be the primary parameter which controls the radon concentrations in the outdoor environment. Indeed, the highest radon levels (> or = 100 Bq m-3 in the atmosphere, > or = 100 mBq m-2 s-1 at the surface of the soil) are mostly observed on lithologies whose mean uranium content can exceed 8 ppm and which correspond to peraluminous leucogranites or metagranitoids derived from uraniferous granitoids.

Study of 222Rn permeation through polymer membranes II: calibration curves of a new device equipped with a polyethylene membrane, for continuous measurement of 222Rn in water-saturated soils.

The permeation of 222Rn through plastic membranes has been studied in order to improve a solid-state measuring device BARASOL and to use it in water-saturated soils. Preliminary results show that polyethylene is the most efficient membrane (sufficiently permeable to radon and impermeable to water). In the present study, we have adapted polyethylene membranes to the BARASOL probe and tested them, in this configuration, with a special experimental set-up. We have shown that it is possible to measure radon concentrations in water of about 1 Bq L(-1) with this probe.

Study of 222Rn permeation through polymer membranes: application to continuous measurement of 222Rn in water.

Membranes that exclude water but are permeable to radon can extend the range of environments where many radon detection systems could operate. We have studied the permeation of 222Rn through polypropylene membranes separating air and water phases. The permeation coefficient and the activation energy were calculated for various conditions. Potential applications, such as in situ detection of radon in water, are discussed.

[Monoclonal gammapathies. (Critical review of 219 cases collected over 3 years)]. / Les gammapathies monoclonales. (Revue critique de 219 dossiers colligés en 3 ans).

219 monoclonal gammapathies have been studied since 1rst January 1973 up to 31st December 1975, regarding 121 males and 98 females, 121 myeloma (mean age: 66 years), 38 Waldenstrom's macroglobulinemia (mean age: 7u years) and 60 various monoclonal gammapathies, among which 19 benign monoclonal gammapathies (mean age: 73 years). 214 immunoelectrophoresis have been performed: 110 IgG, 46 IgA, 49 IgM, 8 light chain myelomas and 1 without M-component myeloma. Bence-Jones proteinuria was detected only in 51,1% of cases.