ABSTRACT
O objetivo desta pesquisa foi avaliar os níveis de concentração de radônio 222Rn em águas de poços da região metropolitana de Curitiba, Paraná. O trabalho apresenta os resultados das concentrações das medidas feitas em águas de poços da região. As concentrações de 222Rn nas amostras das águas de poços foram medidas por meio do monitor de radônio AlphaGUARD. Os cálculos das concentrações de atividade iniciais de radônio na água foram feitos a partir da curva de decaimento do 222Rn e do equilíbrio secular entre o 222Rn e o 226Ra, observados depois de 30 dias. Os resultados indicaram que cerca de 70% dos valores das concentrações de 222Rn ficaram acima do valor recomendado pela USEPA, de 11,1 Bq.L-1, representando risco radiológico causado por este radionuclídeo. O estudo de caso apresentado mostrou que medidas prévias de radônio são recomendadas para que um projeto de construção seja implementado. No caso em questão, observa-se que as concentrações de radônio diminuem cerca de 56% na primeira caixa d'água e 83% na segunda em relação ao poço. Esse fato mostra que as ações para mitigação de radônio são viáveis e não exigem grandes modificações nos sistemas usuais da construção civil.
This research objective was to assess the level of randon-222 concentration in well water of the metropolitan region of Curitiba, Paraná. Current work presents the results of indoor 222Rn activity ground water samples from artesian wells from aquifers of the region. The studies of radon activity in water were performed using the radon detector AlphaGUARD. The calculations of initial radon activity in water were done considering the 222Rn decay correction as well as equilibrium level of 222Rn and 226Ra observed after 30 days of measurements. Obtained results show that about 70% of measured activity levels of 222Rn are higher than the recommended value of 11.1 Bq.L-1, which represent the risk for the human health associated with this radionuclide. The case study showed that previous measurements of radon are recommended for a construction project is implemented. In this case, it is observed that the radon concentrations decrease about 56% in the first water tank and 83% in the second water tank over the well. This fact shows that the actions for mitigation of radon are viable and do not require major modifications to the usual systems of construction.
ABSTRACT
Background: validation of 13C-urea breath test (UBT) in children has been troublesome, The aim of the study was to determine the cut-off value of UBT in childhood using a graphic method and not depending on comparison to the gold standard, Methods: Open, prospective study. The authors studied 84 healthy children [44 (52por cento) female, mean age 6 years (min. 8 mo, max. 12y.0)]. UBT (IRIS, Wagner Analysen-Technik, Bremen, Germany) was perfomed using a dose of 50 mg of 13-C-urea for children up to seven years of age and of 75 mg for children older than seven. breath samples were collected before and 25 (T15), 30(T30) and 45 (T45) min after ingestion of the isotope. Mathematical analysis (log transformation for condensation of the results, Gaussian distribution and Ryan-Joiner normality test) and visual graphic analysis were performed for the determination of the cut-off point Results: According to the graphical and mathematical analysis, the cut-off value was determined to be 40/00 DOB (delta over baseline) at T30 and located at more than 3 SD from the mean for the low urease activity group and at 2.94 SD from the mean for the high urease activity group. 22 children (26por cento) were consideres positiv and 62 (74por cento) negative. Conclusion: This siple low-cost methodology can establish a reliable cut-off point for children, with high sensitivity and specificity. The procedure does not require the use of a comparative method or of a gold standard. Moreover, this practical tool can also be used by the laboratories to monitor UBT perfomance over time