RESUMO
Mining is responsible for the release of metallic pollutants and radioactive materials into the environment, which have the potential to disrupt ecosystems and pose significant risks to human health. Significant mining activity is concentrated in the municipality of Caetité (northeastern Brazil), where Latin America's only active uranium mine and significant iron ore deposits are located. Although previous studies have shown that the regional soil and water resources are highly contaminated by various toxic elements and that exposure to these elements is known to have adverse effects on human health, the health risks in this mining region have never been assessed. The aim of this unprecedented comprehensive investigation was to assess the health, radiological and ecological risks in this mining region, which is home to nearly 100,000 people. To achieve our goal, soil and water samples were collected in the vicinity of the mines and in the main settlements in the region. Fifteen metallic toxic elements were determined using Instrumental Neutron Activation Analysis and Inductively Coupled Plasma Optical Emission Spectrometry. The HERisk code, which follows the main methodological guidelines for risk assessment, was used to quantify human health, radiological and ecological indices. The average values of the total risk and cancer risk indices indicated that region falls into the moderate risk category (1.0 ≤ HItot < 4.0). However, 63% of the sites had high risk values, with Fe, Co and As being the metals contributing most to total and cancer risk, respectively. Near the mining areas, the potential ecological risk can be considered extreme (PERI ≥ 600). The values of the calculated radiological indices correspond to typical values ââin natural uranium areas. However, in the communities near the mine, the dose values are slightly above the permissible limit (1 mSv y-1), so they must be continuously monitored, and risk mitigation measures must be taken.
Assuntos
Mineração , Humanos , Brasil , Medição de Risco , Monitoramento Ambiental , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Exposição Ambiental , Monitoramento de RadiaçãoRESUMO
Risk assessment is considered an essential tool to assist in the management and mitigation of polluted areas, especially those associated with economic activities that significantly degrade the environment, such as mining. However, most of the methodologies of risk assessment adopt the deterministic approach of using a fixed value for ascertaining the hazards derived from exposure to chemical pollutants. However, this is not the case of the Human, Ecological and Radiological Risk (HERisk) code, which allows space-time assessments of ecological, radiological, and human health risks. Indeed, this work aims to describe this new software (enhanced version of HHRISK), which not only improves the performance of the code but also increases its applicability and versatility. To showcase its usefulness in evaluating ecological pollution and human health risk were studied the contents of potentially toxic elements (Co, Cu, Fe, Mn, Ni, Pb, and Zn) in soils and surface waters from the nickel mining area in the municipality of Itagibá (Bahia, Brazil). The obtained results showed that metals are non-homogeneous distributed, suggesting the presence of local enrichment sources, mainly related to human activities. The statistical analyses carried out revealed that mining and agricultural activities are possibly responsible for the contents of these pollutants in both soils and surface waters. The calculated ecological indices of pollution confirmed anthropogenic pollution around the mining area, especially in the locations closest to sterile waste piles. The results of the human health risk assessment revealed that the ingestion of meat and contaminated water are the main routes for entering the potentially toxic elements to the human body and that Co is the chemical specie that poses the highest risk in the entire region. The hazard index (HI) values indicated that the whole area around the mine should be considered as a high risk for human health.
Assuntos
Metais Pesados , Poluentes do Solo , Brasil , China , Cidades , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Medição de Risco , Software , Solo , Poluentes do Solo/análiseRESUMO
Mining, although relevant and indispensable for human socioeconomic development, is considered one of the most polluting anthropogenic activities. Water resources are the most vulnerable environmental compartment to the direct impacts of mining, especially in the semi-arid regions. In these regions, mining activity constitutes an important challenge in the management of water resources; since its impacts can be maximized by the adverse meteorological conditions. This study aimed to assess the level of contamination in water resources of three important mining areas in a semi-arid region, where approximately 70,000 people live. The concentrations of eleven heavy metals in sediment, surface and groundwater samples were determined by ICP OES. The results obtained for water samples indicated significant contamination by Cd, Pb, and U, based on the limits established by Brazilian and international regulatory legislation. In the case of sediment samples, higher concentrations of Cr, Cu, Ni, and V were observed. Pollution indices (PLI, CF and Igeo) revealed moderate to extreme contamination mainly along the Jacaré and Contas rivers. The Pearson correlation, Principal Component, and Hierarchical Cluster analyses were performed to identify patterns in the distribution of elements and common sources of pollution. The results suggested that the concentrations of Co, Cr, Cu, Fe, Mn, Ni, and V were mainly related to mining activities and, to a lesser extent, natural sources. In the case of Cd and Pb, contamination may have an important contribution from fertilizers use, whereas Zn has a mixed source of both lithogenic and anthropogenic origin. On the other hand, the high concentrations of U, specifically in groundwater samples, were associated with geogenic causes. Although the potential ecological risk values indicated a low ecological risk; other sediment quality indices (TEL, PEL, ΣTU, and PEL-Q) revealed that there is 25% of the probability that the content of heavy metals in water resources near the mining areas induces adverse toxic effects on aquatic organisms.
Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , Brasil , China , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Medição de Risco , Recursos HídricosRESUMO
PURPOSE: Optimization studies in digital mammography aid to assure the image quality and radiological protection of the patient. The aim of this work is to test effectiveness and applicability of a method based on a Figure of Merit (FOM=(IQFinv)2/AGD) to improve all the exposure parameters (Target/Filter combination, kVp and mAs) in order to improve the image acquisition technique that will provide the best compromise between image quality and the average glandular dose (AGD). METHODS: A contrast-detail analysis, employing the test object CDMAM, was carried out for the digital mammography unit manufactured by Lorad Hologic - model Selenia. We simulated two breast thicknesses using phantoms and a Figure of Merit as optimization tool, which includes an indicator of image quality, the IQFinv and the average glandular dose. Images of the ACR and TORMAM phantoms were obtained with both, automatic and optimized exposure parameters. In order to compare the image quality, the SNR (Signal to Noise Ratio) was measured in each image. RESULTS: In the two phantoms, for both 4.5 and 7.5cm thicknesses, the AGDs obtained with the optimized parameters show a reduction. In addition, the images obtained with the optimized exposure parameters, had the same or a better image quality when compared to the images obtained using the automatic mode. CONCLUSIONS: The proposed optimization methodology proved to be an effective tool to improve the digital mammography unit, due to the use of objective metrics for evaluation and validation of the results.