In a 1990-1996 case-control study in western Germany, the authors investigated lung cancer risk due to exposure to residential radon. Confirmed lung cancer cases from hospitals and a random sample of community controls were interviewed by trained interviewers regarding different risk factors. For 1 year, alpha track detectors were placed in dwellings to measure radon gas concentrations. The evaluation included 1,449 cases and 2,297 controls recruited from the entire study area and a subsample of 365 cases and 595 controls from radon-prone areas of the basic study region. Rate ratios were estimated by using conditional logistic regression adjusted for smoking and for asbestos exposure. In the entire study area, no rate ratios different from 1.0 were found; in the radon-prone areas, the adjusted rate ratios for exposure in the present dwelling were 1.59 (95% confidence interval (CI): 1.08, 2.27), 1.93 (95% CI: 1.19, 3.13), and 1.93 (95% CI: 0.99, 3.77) for 50-80, 80-140, and>140 Bq/m3, respectively, compared with 0-50 Bq/m3. The excess rate ratio for an increase of 100 Bq/m3 was 0.13 (-0.12 to 0.46). An analysis based on cumulative exposure produced similar results. The results provide additional evidence that residential radon is a risk factor for lung cancer, although a risk was detected in radon-prone areas only, not in the entire study area.

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Die dunkelgrünen Oxydationsprodukte von Eisen(II)‐hydroxyd entsprechen nicht einer einzigen Verbindung; sie können vielmehr Hydroxyd oder basisches Salz sein. Bei der Oxydation von Fe(OH)2 bleibt das C6‐Gitter erhalten, bis zu einem Gehalt von etwa 10% an Fe3+‐Ionen. Hydroxyd mit stabilisierten molekularen Schichten geht bei der Oxydation unter stetiger Abnahme des Abstandes der Eisenionen in den Schichten in ein laminares Eisen(III)‐hydroxyd über. Die Farbe bleibt bis zu einem Gehalt von mehr als 50% Fe3+ grün. Aus gepufferter Eisen(II)‐chloridlösung fällt bei der Oxydation ein basisches Eisen(II)(III)‐chlorid aus, das die gleiche oder eine ähnliche Struktur hat wie die grünen basischen Kobalthalogenide. Die Idealformel ist 4Fe(OH)2, 1FeOCl, xH2O, doch kann ein beträchtlicher Teil der Fe2+ durch Fe3+ ersetzt sein. Die dunkelgrüne Farbe dieser Verbindungen ist auf den leichten Elektronenaustausch zwischen den zwei‐ und dreiwertigen Eisenionen im Gitter zurückzuführen.

Our data indicate a small increase in lung cancer risk as a result of residential radon that is consistent with the findings of previous indoor radon and miner studies.

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Results are presented of measurements of the activity concentrations of 222Rn and its short-lived decay products and the 212Pb/212Bi concentrations in more than 200 dwellings in West Germany and in the open air. For more than 130 measurements of the equilibrium factor F in dwellings the median value was found to be 0.3. Measurements of F in the open air under various conditions resulted in a mean value of about 0.4. The results of the investigations showed that indoors F depends only slightly on ventilation, indoor 222Rn concentration and other parameters. The equilibrium factor F in the open air, however, was found to depend on meteorological conditions. Empirical correlations from the data obtained for the daughter/222Rn concentration ratios were derived to provide relations for the prediction of the individual daughter product concentrations at a measured 222Rn level. It was established that the daughter/222Rn concentration ratios for indoor air do not change within the range of 222Rn concentrations investigated (1-370 Bq X m-3). These relations, however, are not valid for the daughter/222Rn concentration ratios in outdoor air. The correlations derived further suggest that the individual daughter product concentrations may be assessed with sufficient accuracy by only measuring the 222Rn concentrations. Thus the daughter ratios obtained in this way should enable good estimates of the lung dose for members of the public due to inhalation of the short-lived 222Rn daughters and the dose contribution of the individual 222Rn-daughter products.

This paper discusses different possibilities of deriving reference values for the natural radioactivity concentrations in building materials to estimate possible additional radiation exposure for the population. Based on comprehensive experimental and theoretical investigations the consequences of the resulting hypothetical reference activity concentrations in building materials, applying different dose limits, were examined. The calculation of the activity concentration standards was performed for standard conditions obtained by earlier studies on exhalation of Radon-222 and Radon-220 from building materials.