A new approach for the determination of 210Pb by liquid scintillation counting.

A new approach to the calibration procedure is presented, as there is no need to discount bismuth from lead spectrum when constructing the efficiency curve. This work presents two calibration methods: one considering mostly lead spectrum contributions and other that considers both lead and bismuth contributions. Both methodologies provide consistent results when evaluated in an intercomparison program. Furthermore, this methodology allows simultaneous analysis of several samples and is suitable for any type of sample after proper digestion in liquid form.

Evaluation of Reference Urinary Excretion Concentrations of Selected Radionuclides Corresponding to Clinical Decision Guides for Application in Radiological and in Nuclear Emergencies.

Radiological or nuclear emergency situations could lead to incorporation of radionuclides by the population. Intakes of radionuclides can be evaluated through measurements of radionuclides present in organs and tissues, or in urinary and/or fecal excretion. In an emergency situation involving a large number of people, the decision to provide medical treatment to an individual will likely be based on a single measurement. For that purpose, the National Council on Radiation Protection and Measurements (NCRP) has presented the Clinical Decision Guide (CDG) quantity, which corresponds to an intake amount of a radionuclide by an individual for which treatment is recommended. However, the NCRP recommends using one-fifth of the CDG for pregnant women and children which could result in an effective or equivalent dose in excess of the dose constraint. Tables of reference urinary excretion concentrations which are associated with an intake of one CDG for inhalation and ingestion intake scenarios of several forms of 60Co, 90Sr, 137Cs, 192Ir, 238Pu, 239Pu and 241Am have been calculated and are presented for the following categories of members of the public: 3 months old, 1 y, 5 y, 10 y, 15 y, adult and pregnant woman.

Environmental influence on coprophagous Scarabaeidae (Insecta, Coleoptera) assemblages in the Pantanal of Mato Grosso.

Here we examine assemblage structure of coprophagous Scarabaeidae (dung beetles) in the Pantanal of the state of Mato Grosso with respect to flooding regimes, soil texture, leaf litter volume and tree dominance in native and exotic pastures. Samples were collected along 30 transects of 250 m in length in a 5×5 km grid (25 km2). Five pitfalls baited with human feces were placed in each transect. A total of 1692 individuals in 19 species were captured, the majority in the subfamily Scarabaeinae and Aphodiinae. Assemblages were influenced by the duration of flooding and leaf litter volume. None of the other habitat variables was correlated with species richness. Cultivated pastures with exotic grasses were unimportant for composition of the assemblages of beetles. These results indicate that duration of flooding is the most important regulating force in this community.

Environmental influence on coprophagous Scarabaeidae (Insecta, Coleoptera) assemblages in the Pantanal of Mato Grosso

Abstract Here we examine assemblage structure of coprophagous Scarabaeidae (dung beetles) in the Pantanal of the state of Mato Grosso with respect to flooding regimes, soil texture, leaf litter volume and tree dominance in native and exotic pastures. Samples were collected along 30 transects of 250 m in length in a 5×5 km grid (25 km2). Five pitfalls baited with human feces were placed in each transect. A total of 1692 individuals in 19 species were captured, the majority in the subfamily Scarabaeinae and Aphodiinae. Assemblages were influenced by the duration of flooding and leaf litter volume. None of the other habitat variables was correlated with species richness. Cultivated pastures with exotic grasses were unimportant for composition of the assemblages of beetles. These results indicate that duration of flooding is the most important regulating force in this community.

Resumo Esse estudo avaliou a estrutura espacial de assembleias de Scarabaeidae coprófagos no Pantanal de Mato Grosso, em função do tempo de inundação, textura do solo, volume da serapilheira, dominância de arbóreas, pastagens nativa e exótica. As coletas foram realizadas em 30 transectos de 250 m cada distribuídos sistematicamente em uma área de 25 km2. Cinco armadilhas pitfall iscadas com fezes humanas foram instaladas em cada transecto, e obtidos 1.692 indivíduos distribuídos em 19 espécies pertencentes às subfamílias Scarabaeinae e Aphodiinae. A estrutura e composição das assembleias foram afetadas pelo tempo de inundação e o volume da serapilheira. Todas as variáveis explanatórias foram fracamente correlacionadas e de forma não significativa com a riqueza de espécies. A existência de pastagem exótica não afetou a composição das assembleias de besouros. Esses resultados indicam que o tempo de inundação é a principal força reguladora dessa comunidade no ambiente pantaneiro.

Environmental influence on coprophagous Scarabaeidae (Insecta, Coleoptera) assemblages in the Pantanal of Mato Grosso / Influência ambiental sobre assembleias de Scarabaeidae coprófagos (Insecta: Coleoptera) no Pantanal de Mato Grosso

Abstract Here we examine assemblage structure of coprophagous Scarabaeidae (dung beetles) in the Pantanal of the state of Mato Grosso with respect to flooding regimes, soil texture, leaf litter volume and tree dominance in native and exotic pastures. Samples were collected along 30 transects of 250 m in length in a 5×5 km grid (25 km2). Five pitfalls baited with human feces were placed in each transect. A total of 1692 individuals in 19 species were captured, the majority in the subfamily Scarabaeinae and Aphodiinae. Assemblages were influenced by the duration of flooding and leaf litter volume. None of the other habitat variables was correlated with species richness. Cultivated pastures with exotic grasses were unimportant for composition of the assemblages of beetles. These results indicate that duration of flooding is the most important regulating force in this community.

Resumo Esse estudo avaliou a estrutura espacial de assembleias de Scarabaeidae coprófagos no Pantanal de Mato Grosso, em função do tempo de inundação, textura do solo, volume da serapilheira, dominância de arbóreas, pastagens nativa e exótica. As coletas foram realizadas em 30 transectos de 250 m cada distribuídos sistematicamente em uma área de 25 km2. Cinco armadilhas pitfall iscadas com fezes humanas foram instaladas em cada transecto, e obtidos 1.692 indivíduos distribuídos em 19 espécies pertencentes às subfamílias Scarabaeinae e Aphodiinae. A estrutura e composição das assembleias foram afetadas pelo tempo de inundação e o volume da serapilheira. Todas as variáveis explanatórias foram fracamente correlacionadas e de forma não significativa com a riqueza de espécies. A existência de pastagem exótica não afetou a composição das assembleias de besouros. Esses resultados indicam que o tempo de inundação é a principal força reguladora dessa comunidade no ambiente pantaneiro.

Morphometry of Cornops aquaticum (Orthoptera: Acrididae: Leptysminae) in the Pantanal of Mato Grosso, Brazil.

Insects show morphometric variations associated with the environment that may be the result of phenotypic response or genetic inheritance, or both. Thereby, studies that emphasise the variability in body size are very useful for understanding the dynamics and the stability of ecological systems. Cornops aquaticum (Bruner, 1906) (Acrididae) is a semi-aquatic grasshopper, distributed from the southeast of Mexico to the south of Buenos Aires Province, Argentina, and is intimately associated with the aquatic macrophytes Eichhornia spp. and Pontederia spp. In its wide habitat distribution, C. aquaticum shows variations in its life cycle and morphometric differences that were observed suggesting geographic and host plant influence. Considering these findings, this study aimed to find out the morphometric characteristics of this species at the Pantanal of Poconé - MT, using the protocol of the project "HICWA - Host-Insect Coevolution on Waterhyacinth", as well as to assess possible differences in each stage of development between the sexes and among seasonal periods (flood, high water, low water and dry). During 12 months a total of 600 individuals were collected in monthly collections of 50 grasshoppers, and of this total, 261 were adults and 339 nymphs. The following measurements were taken: total length (A); body length (B); wing length (I) and measurement of the hind femur (H). The results showed that both male and female have different measurements but not correlated with seasonal periods. The average obtained for each character and the seasonality showed the highest values during the flood period. In nymphs, the measurement of the posterior femur presented the lower variation between individuals and characters.

A mobile bioassay laboratory for the assessment of internal doses based on in vivo and in vitro measurements.

Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.

Methodology for radionuclides quantification through "in vitro" bioassay.

In Brazil, the radionuclides used for therapy are: (131)I, (153)Sm, (90)Y and (177)Lu, both for routine or research protocols. The radionuclide activity excreted by patients may be quantified by bioassay analysis and constitutes a powerful tool for individual treatment planning. The Bioassay Laboratory (LBIOVT) of the Institute of Radiation Protection and Dosimetry (IRD) has equipments for gamma and beta spectroscopy. These systems are calibrated in energy and efficiency using reference sources supplied by the National Laboratory of Radiation Metrology (LMNRI/IRD). The LBIOVT has operational procedures according ISO-ABNT-17025 recommendations and participates of international and national intercomparisons. The patient samples are collected immediately after radiopharmaceutical administrations, at the hospital or at the patient residence, and are handled, stored and transported according national radiation protection regulations. The radionuclide specific activity (Bq/L) is referenced to date and time of excretion, for the estimation of the individual biological half-live. The volume of excreta may carefully manipulated in order to avoid losses and misinterpretation in the activity quantification. The process of the LBIOVT accreditation and its participation in intercomparisons may guarantee the confidence of the results, allowing the minimization of the uncertainties in the individual monitoring.

Evaluation of internal exposure of nuclear medicine staff through in vivo and in vitro bioassay techniques.

The manipulation of a wide variety of unsealed sources in Nuclear Medicine results in a significant risk of internal exposure of the workers. 131I should be highlighted among the most frequently used radionuclides because of its large application for diagnosis and therapy of thyroid diseases. The increasing use of radionuclides for medical purposes creates a demand for feasible methodologies to perform occupational control of internal contamination. Currently in Brazil, there are approximately 300 nuclear medicine centres in operation but individual monitoring is still restricted to the control of external exposure. This work presents the development of in vivo and in vitro bioassay techniques aimed to quantify incorporation of radionuclides used in Nuclear Medicine. It is also presented the results of a preliminary survey of internal exposure of a group of workers involved in the preparation of therapeutic doses of 131I. Workers were monitored with a gamma camera available in the Nuclear Medicine Service of the University Hospital of Rio de Janeiro and at the Institute of Radiation Protection and Dosimetry Whole-Body Counter (IRD-WBC). The in vivo detection systems were calibrated with a neck-thyroid phantom developed in IRD. Urine samples from radiopharmacy workers were collected after preparation and administration of therapeutic doses (10-250 mCi) of 131I and measured with a HPGe detection system available in the Bioassay Laboratory of IRD. The results show that the bioassay methods developed in this work present enough sensitivity for routine monitoring of nuclear medicine workers. All workers monitored in this survey presented positive results for 131I in urine samples and two workers presented detectable activities in thyroid when measured at the IRD-WBC. The highest committed effective dose per preparation was estimated to be 17 microSv.

Determination of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb concentration in excreta samples of inhabitants of a high natural background area.

The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper, the concentrations of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1) for 238U, 9.2 +/- 4.0 mBq g(ash)(-1) for 234U, 7.0 +/- 4.2 mBq g(ash)(-1) for 232Th, 256.1 +/- 134.6 mBq g(ash)(-1) for 228Th, 335.5 +/- 192.8 mBq g(ash)(-1) for 228Ra, 156.6 +/- 74.1 mBq g(ash)(-1) for 226Ra and 66.7 +/- 17.7 mBq g(ash)(-1) for 210Pb. The results were compared with background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.