Building material radon emanation and exhalation rate: Need of a shared measurement protocol from the european database analysis.

In this paper the authors present a collection of radon emanation and exhalation rate data of about 2000 samples of building materials used in Europe. The data analysis highlighted some critical issues, such as the use of different units to express radon exhalation rate, the use of different measurement techniques and the general lack of information about density and thickness of samples. In many cases these differences of type and amount of information make difficult a reliable comparison of the obtained data. In the light of these considerations, the need arises to start, at both national and European level, a research activity aimed to develop a shared protocol for measuring the radon exhalation rate based on widely used and reliable measurement techniques. At European level, this protocol could support in forthcoming EU Member States national radon action plans, to take into account the contribution of building materials to the indoor radon concentrations.

Updated database on natural radioactivity in building materials in Europe.

The paper presents the latest collection of activity concentration data of natural radionuclides (226Ra, 232Th and 4 K) in building materials. This database contains about 24200 samples of both bulk materials and their constituents (bricks, concrete, cement, aggregates) and superficial materials used in most European Union Member States and some European countries. This collection also includes radiological information about some NORM residues and by-products (by-product gypsum, metallurgical slags, fly and bottom ashes and red mud) which can be of radiological concern if recycled in building materials as secondary raw materials. Moreover, radon emanation and radon exhalation rate data are reported for bricks and concrete.

Radiological characterization of the ancient Roman tuff-pozzolana underground quarry in Orvieto (Italy): A natural laboratory to revisit the interactions between radionuclides and aerosols.

Orvieto (Italy) has a large network of underground tunnels quarried to extract tuff and pozzolana by Etruscans and Romans. One of these tunnels was chosen as natural laboratory to compare different radiation measurement and dose assessment methods. Indeed, tuff and pozzolana are very rich in natural radioactivity and are interesting from the radiation protection point of view since they are still used as building materials. In order to characterize this site an in situ experimental procedure was followed. It consisted in measurements carried out with different instruments: two portable gamma ray spectrometers, two gamma dose rate meters, two radon monitors and one two channel working level monitor. Samples of tuff and pozzolana stones were also collected to be measured with gamma spectrometry in laboratory. Due to the high content of 238U, 232Th (more than 200 Bq kg-1 for both radionuclides) and 40K (more than 2000 Bq kg-1) of tuff and pozzolana, elevated levels of exposure to natural radioactivity were found: indeed, with different instruments and approach, a gamma dose rate of about 1 µGy h-1 and an average radon concentration of about 10,000 Bq m-3, with a Potential Alpha Energy Concentration (PAEC) of 288 MeV cm-3, were measured. The radiological characteristics of Orvieto underground quarry make it a perfect site for "in field" intercomparisons of different measurement and dose assessment methods.

Estonian waterworks treatment plants: clearance of residues, discharge of effluents and efficiency of removal of radium from drinking water.

Considerable levels of radium were detected in a certain fraction of the Estonian drinking water supply network. Some of these waterworks have treatment systems for the removal of (mainly) iron and manganese from drinking water. Three of these waterworks and another one equipped with a radium removal pilot plant were examined, and a specific study was conducted in order to assess the environmental compatibility of effluents and residues produced in the plants. (226)Ra and (228)Ra activity concentrations were analysed in both liquid (backwash water) and solid (sand filter and sediment) materials to evaluate their compliance, from the radiological point of view, with current Estonian legislation and international technical documents that propose reference levels for radium in effluents and residues. Also with regard to water treatment by-products, a preliminary analysis was done of possible consequences of the transposition of the European Basic Safety Standards Draft into Estonian law. Radium removal efficiency was also tested in the same plants. Iron and manganese treatment plants turned out to be scarcely effective, whilst the radium mitigation pilot plant showed a promising performance.

Natural radioactivity in building material in the European Union: robustness of the activity concentration index I and comparison with a room model.

Using a wide database collected in the last 10 years, the authors have calculated the activity concentration index I for many building materials in the European Union. Suggested by a European technical guidance document, the index I has recently been adopted as a screening tool in the proposal for the new Euratom basic safety standards directive. The paper analyses the possible implications of the choice of different parameters for the computation of index I, i.e. background to be subtracted, dose criteria, etc. With the collected data an independent assessment of gamma doses was also made with an ISS room model, choosing reasonable hypotheses on the use of materials. The results of the two approaches, i.e. index I and a room model, were compared.

Natural radioactivity in building materials in the European Union: a database and an estimate of radiological significance.

The authors set up a database of activity concentration measurements of natural radionuclides (²²6Ra, ²³²Th and 4°K) in building material. It contains about 10,000 samples of both bulk material (bricks, concrete, cement, natural- and phosphogypsum, sedimentary and igneous bulk stones) and superficial material (igneous and metamorphic stones) used in the construction industry in most European Union Member States. The database allowed the authors to calculate the activity concentration index I--suggested by a European technical guidance document and recently used as a basis for elaborating the draft Euratom Basic Safety Standards Directive--for bricks, concrete and phosphogypsum used in the European Union. Moreover, the percentage could be assessed of materials possibly subject to restrictions, if either of the two dose criteria proposed by the technical guidance were to be adopted.

Radioactivity in building materials: room model analysis and experimental methods.

First, models (room models) published in the international literature allowing the exposure to gamma radiation indoors due to building materials to be assessed are reviewed and discussed. For one of them, a sensitivity analysis concerning the effect of changing the parameters (e.g. dimensions of the room, thickness and density of the walls, etc.) used in calculations is performed. Second, a method is proposed for calculating the activity concentration in the walls of a room using: (a) the measured absorbed dose rate in air in the room; (b) the contributions of natural radionuclides (238U, 232Th and 40K) to the absorbed dose rate in air assessed by means of gamma spectrometry indoors; and (c) the specific dose rate (nGy h(-1) per Bq kg(-1)) of natural radionuclides, for the chosen room geometry, calculated with the room model.

In situ gamma spectroscopy to characterize building materials as radon and thoron sources.

In situ gamma spectroscopy is widely utilized to determine the outdoor gamma dose rate from the soil and to calculate the natural and artificial radionuclide concentration and their contribution to the dose rate. The application of in situ gamma spectroscopy in indoor environments can not supply quantitative information about activity concentration of radionuclides in building materials, but this technique can provide interesting information about building materials as radon source. In fact, a method based on analyses of gamma spectra data has been developed by the authors to provide, in field, quantitative estimation of disequilibrium in 226Ra and 228Ac sub-chains due to 222Rn and 220Rn exhalation. The method has been applied to data of gamma spectroscopy measurements carried out with HPGe detector (26%) in seven dwellings and one office in Rome. The first results of the data analysis show that, as regards especially the 226Ra sub-chain disequilibrium, different building materials (tuff, concrete, etc.) can show very different characteristics. If, in addition to the spectrometric data, other indoor environment parameters (indoor gamma dose rates, room dimensions, wall thickness, etc.) (Bochicchio et al., Radiat Prot Dosim 1994;56(1-4):137-140; Bochicchio et al., Environ Int 1996a;22:S633-S639) are utilized in a room model, an evaluation of 226Ra, 228Ac and 40K activity concentration and an indication of the exhalation features, by means of estimation of exhaled 222Rn activity concentration, can be achieved.

Experimental and measurement issues in natural radioactivity.

The paper deals with some open experimental problems in the field of natural radioactivity. Its aim is to stimulate discussion on the type of research efforts needed in the field and to be planned for the future. The review, which makes no claims to completeness. analyses some issues in gamma spectrometry of natural radionuclides, and the measurement of natural radioactivity in non-nuclear industries and of 222Rn and 220Rn concentration in air.

Prenatal exposure to ionizing radiation: sources, effects and regulatory aspects.

Knowledge and awareness of physicians and the general public concerning the risks of prenatal exposure to ionizing radiation are important when developing a correct attitude to ionizing radiation. This is particularly important in the justification of medical diagnostic exposure of pregnant women and in case of possible accidents. The present paper reviews the most recent data on the effects of prenatal exposure to ionizing radiation reported in the scientific literature and in documents of international organizations dealing with this subject. Potentially significant exposure for women of childbearing age in medical diagnostics, working conditions and environmental contamination following the Chernobyl accident are reported. Some examples of doses associated with medical exposure in the course of diagnostic examinations with X-rays and radiopharmaceuticals, and occupational exposure in workplaces are given. Lastly, the regulatory aspects of the European Union directives and the Italian legislation on medical and occupational exposure of women during pregnancy or in reproductive age are reviewed.

[New aspects in the evaluation of risk factors for fetal development]. / Nuovi aspetti nella valutazione di fattori di rischio per lo sviluppo embrionale.

Much knowledge concerning the effects of xenobiotics on prenatal development derive from experimental studies, which are generally performed on laboratory animals according to standardized protocols. Conventional in vivo studies should be integrated by other models within a scientifically-based risk assessment strategy. The paper reviews a few in vitro and/or in vivo approaches: identification of critical effects through the characterization of the pathogenesis as well as the use of dose-response relationships; alternative models to identify reproductive risks from single substances and/or mixtures present in the environment; interactions between in vitro and in vivo studies in the risk assessment of solvents: embryonic metabolism in teratogenicity; interactions between experimental and epidemiological studies to understand the pathogenesis of embryolethality; risk assessment of the effects of prenatal exposure to ionizing radiations.

Results of the representative Italian national survey on radon indoors.

A representative national survey on population exposure to radon in Italian dwellings was carried out from 1989 to 1994, with the co-operation of the National Health Service. The measurements were performed by 19 Regional Laboratories, all using the same techniques and protocols. A stratified, two-stage sampling procedure was used to sample families. The sampled families were approached door-to-door to maximize response. To optimize the quality of the measurements, two dosimeters, each containing two alpha track detectors, were placed together in one room (typically the bedroom) for two consecutive 6-mo periods. The distribution of annual radon concentration was derived from measurements in 4,866 dwellings. The average value is 75 Bq m(-3) and the fractions of dwellings above the reference levels of 150, 200, 400, and 600 Bq m-3 are 8.7%, 4.7%, 1.0%, and 0.2%, respectively. The geometric mean is 57 Bq m-3 while the geometric standard deviation is 2.0. The average values in the Italian Regions fall within the 20-120 Bq m-3 range. When the average radon concentration is examined vs. story, building materials seem to play a significant role. The average lifetime risk of lung cancer for chronic radon exposure of Italian population at home would be about 5 x 10(-3), using the risk factor proposed by the ICRP in 1993.

Evaluation on the effects of cutaneous chemical agents by nuclear magnetic resonance techniques.

A change in relaxation times has been determined in skin tissues after administration of hyaluramine, by means of nuclear magnetic resonance. Results are discussed in terms of water redistribution between the free and bound compartment.