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The first Brazilian historical mortality cohort study on miners was conducted. The cohort consisted of 3224 workers in the underground coal mining industry in southern Brazil. This industry has been operating since 1942 without compliance with any regulatory standards, since there were no relevant national regulations. Over almost 60 years, about 5000 workers were exposed to high levels of radiation. However, later radiation exposure was significantly reduced, particularly that due to radon exposure. Recent radon concentration measurements indicated an average annual exposure to radon progeny of 2.1 WLM, ranging from 0.2 to 7.2 WLM. As radon exposure in the past was unknown, it can be suggested that mine workers have not been working safely as regards the health hazard related to radon and radon progeny exposure. The cohort inclusion criteria are as follows: (a) all male employees who had worked for at least one year at the coal mine; (b) workers with complete workplace information (underground and surface); (c) employment hiring between 1945 and 1997 and (d) the worker must have been alive on 1 January 1979. Through multiple strategies of search it was possible to follow up the members of the cohort with a success rate of 92%. This paper presents the characteristics of the study population and provides information about the feasibility of conducting a retrospective mortality study in Brazil, taking into account the methodological and logistical difficulties of conducting such a study in a developing country.

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The main source of radiation exposure in most underground mining operations is radon and radon decay products. The situation of radon exposure in underground mining in Brazil is still unknown, since there has been no national regulation regarding this exposure. A preliminary radiological survey in nonuranium mines in Brazil indicated that an underground coal mine in the south of Brazil had high radon concentration and needed to be better evaluated. This paper intends to present an assessment of radon and radon decay product exposure in the underground environment of this coal mining industry and to estimate the annual exposure to the workers. As a product of this assessment, it was found that average radon concentrations at all sampling campaign and excavation sites were above the action level range for workplaces of 500-1500 Bq m(-3) recommended by the International Commission on Radiological Protection--ICRP 65. The average effective dose estimated for the workers was almost 30 times higher than the world average dose for coal miners.

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This study discusses the methodology for measuring and assessing the radon concentration in indoor and outdoor environments. A research study was developed to investigate the long-term behavior of the diurnal and seasonal fluctuations of radon (222)Rn EEC (Equilibrium-Equivalent Concentration) and the influence of temperature and other climatic aspects on this behavior. The study was performed by means of both integrated and instantaneous measurements of radon and its short-lived daughter products for a period of 1 year in an indoor environment in Rio de Janeiro city, Brazil (reference environment), with continuous measurement, using a radon monitor with an alpha spectrometry detector. For a single day, a variability of about 50% could be observed in the (222)Rn EEC values measured on a hourly basis, with a maximum occurring early in the morning and a minimum in the afternoon. For the long-term period, seasonality is responsible for a two order of magnitude variability, with a maximum of 50 Bq.m(-3) in winter (dry season) and a minimum of 0.5 Bq.m(-3) in the summer months (wet season), outdoors. A negative correlation with temperature was observed. The conclusions of this experiment led to a survey of radon gas concentration in dwellings in Rio de Janeiro city, Brazil, in urban area with nearly 7 million inhabitants, through integrated sampling methods, using a Solid State Nuclear Track Detectors Technique (SSNTD). The study was conducted in different geomorphological locations in town. The radon gas concentration in Rio de Janeiro dwellings ranged from 5 Bq.m(-3) to 200 Bq.m(-3). A good correlation between indoor radon gas concentration and location of dwellings was observed. The seashore areas presented the lowest levels of indoor radon concentration, whereas the highest levels were found close to the mountains.

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Two niobium mining facilities located at two different geological settings were selected as case studies for assessing the radiological impacts associated with mining and milling activities. The impacts were assessed both for operational and post-operational (future unrestricted use of the area) scenarios. The work methodology encompassed sampling and analysis of different materials along the operational process, including wastes, effluents and by-products, mass balance calculations, and dose assessment. The exposure scenario considered during the operational phase included the land use by hypothetical groups of members of the general public. In the case of post-operational phase the possible occupation of contaminated areas was considered. The results pointed out that during the operational phase of the investigated industries no relevant impacts could be attributed to them. However, in the case of the potential occupation of the contaminated areas where the wastes are being deposited, the unrestricted use of these areas cannot be accepted in terms of the relevant radiation protection requirements.

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The concentrations of the naturally occurring radionuclides 232Th, 238U, 210Pb, 226Ra and 238Ra were determined in the vegetables (leafy vegetables, fruit, root, bean and rice) and derived products (sugar, coffee, manioc flour, wheat flour, corn flour and pasta) consumed most by the adult inhabitants of Rio de Janeiro City. A total of 88 samples from 26 different vegetables and derived products were analyzed. The highest contribution to radionuclide intake arises from bean, wheat flour, manioc flour, carrot, rice, tomato and potato consumption. The estimated daily intakes due to the consumption of vegetables and derived products are 1.9 mBq of 232Th (0.47 microg), 2.0 mBq of 238U (0.17 microg), 19 mBq of 236Ra, 26 mBq of 210Pb and 47 mBq of 228Ra. The estimated annual effective dose due to the ingestion of vegetables and their derived products with the long-lived natural radionuclides is 14.5 microSv. Taking into account literature data for water and milk from Rio de Janeiro the dose value increases to 29 microSv, with vegetables and derived products responsible for 50% of the dose and water for 48%. 210Pb (62%) and 228Ra (24%) were found to be the main sources for internal irradiation.

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Niobium, phosphate, coal and gold mining facilities have been selected as case studies with the aim of identifying possible sources of radiological impact during and after cessation of industrial operations. The results have shown that acid drainage, as well as chemical processing of mineral ores, constitute relevant impact indicators for present-day and future scenarios. The possible use of solid wastes abandoned at the end of the operations represents a long-term radiological concern. Therefore, it is necessary that Brazilian legislation for environmental licensing be revised taking into account the potential environmental and radiological impacts caused by these industries and establishing remedial procedures for waste storage areas in the existing sites. The indicators developed and procedures carried out can be used in screening for decisions on the adoption of regulatory requirements for practices at such types of installations.

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Based on production data published by the Brazilian Mineral Water Producers Association, bottled mineral waters were bought at the market, covering, at least, 50% of the annual production of each Brazilian geographical region. 228Ra, 226Ra and 210Pb were analyzed and the weighted mean values obtained for Brazilian mineral waters were 0.097, 0.027 and 0.066 Bq l-1 respectively. Individual effective dose rate estimates due to ingestion of mineral water in Brazil were of the order of 10-100 microSv yr-1, depending on the geographical region. Based on the available data, it was also possible to evaluate the per caput effective dose rate and the highest value obtained was 4.3 microSv yr-1 for the northern region.

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This meeting brought together many outstanding specialists and scientists from different countries and it is a witness to recognise the large contribution made in the prevention of radiation health hazards by the Institute of Radiation Protection and Dosimetry in Brazil after twenty five years of his creation. One important aspect in the development of REMPAN is further strenghthening coordination and cooperation between different elements of its infrastructure. In this context, WHO/HQ initiated the integration process within its programme activity in the field of radiation protection. This process is aimed, first of all, at combining the efforts of WHO/HQ and all WHO/ROs in the implementation of a comprehensive programme on the prevention of radiation health hazards. There are seven elements within this programme: 1. Scientific assessment; 2. National programme development; 3. Emergency preparedness and assistance; 4. Radiation monitoring; 5. Follow-up exposed population; 6. Research; 7. Networking for information exchange

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The Goiânia accident, Brazil, was used as an opportunity to quantify the contributions of different mechanisms, in particular mass loading, leading to caesium uptake by leafy vegetables in a semi-urban environment contaminated with 137Cs. Soil splash contributions of 70-90% were quantified for lettuce and 50-60% for green cole. Soil mass loadings of 130 and 340 mg.g-1 were estimated for lettuce and 120 and 150 mg.g-1 for green cole. The results call attention to the potential significant contribution of the soil splash to radionuclide uptake by plants which have the edible plant parts near the soil surface (within 30-40 cm) and low root uptake factors. For radiological assessment purposes it could also be necessary to consider the contamination of crops by this mechanism.

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In September 1987, a powder radioactive source was removed from a teletherapy machine in Goiânia, Brazil. Subsequently, it was ruptured in a residential garden causing the dissemination of 137Cs throughout the city. Soil resuspension processes and burial of contaminated house waste in unused gardens were the major contributors to the Cs dissemination in soils at the secondary contaminated sites. Only locations within a radius of 50 m from the primary contaminated sites presented the need for remedial action. The radiation dose-rate measurements and the soil profiles were good indicators of the extent of the secondary contamination and were fundamental for the decisions taken regarding decontamination procedures. In cases of surface contamination, 60% on average of the total activity remained in the upper 1.5-cm layer over the first 5 mo after the accident, and topsoil removal proved to be an effective procedure for decontamination.

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A study of the (226)Ra contamination of the river sediments surrounding the Brazilian uranium mining and milling facilities was carried out. The nondetrital (226)Ra concentrations were determined performing a 0.5 N HCl leaching. Some preliminary speciations experiments using Tessier's sequential extraction procedure were also carried out. (228)Ra was used as a monitor of the natural variations. In general one could not observe increase in the non-detrital (226)Ra fraction between the pre-operational and operational data. Additionally, speciations experiments have shown the exchangeable fraction to be the main one responsible for (226)Ra content. Although the results indicate that the sediment is an important means of radium downstream transport, its availability suggests the soluble form to be the main path through the main foodchain. Attention must be paid to the release of (226)Ra bound to barium sulphate from the chemical processing effluent since increments of that fraction were observed in bottom sediments.

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The first Brazilian uranium mine and mill are located on the Pocos de Caldas plateau, in the Central State of Minas Gerais. The pre-operational environmental survey was carried out over a period of two years by the Brazilian Nuclear Energy Commission (CNEN), through the Instituto de Radioprotecão e Dosimetria (IRD). The selection of the materials to be monitored, the sampling points and the radionuclides to be analysed were based on critical parameters taking into account the meteorological and hydrological characteristics of the site as well as land use. The results obtained are sufficient to characterize the environmental background of the area, and will allow an assessment of the environmental impact due to the operation of the facility and an evaluation of the adequacy of the effluent emission control measures. In relation to their contribution to the population dose, the results indicated that 226Ra and 210Pb will be the important radionuclides.

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