dissertação
Bioacessibilidade de arsênio em área de mineração de ouro, Paracatu (MG)
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UNIVERSIDADE FEDERAL DE LAVRAS
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Áreas de mineração de ouro são importantes do ponto de vista do desenvolvimento econômico, porém os solos destas áreas são drasticamente alterados por atividades antrópicas. Além disso, o material de rocha que contém o ouro, geralmente está associado à presença do arsênio (As), um elemento tóxico e carcinogênico. Tal elemento, quando exposto à camada superficial do solo, sofre alterações na sua forma química e ou é transferido para outros meios (e.g., água, ar), podendo entrar na cadeia trófica. Crianças, em contato frequente com solos contaminados por As, têm como principal rota de exposição ao elemento, a ingestão involuntária desses solos. Considerando a importância dessa via de exposição, testes de bioacessibilidade de As são utilizados no intuito de estimar a contribuição desta rota em uma avaliação de risco à saúde humana. Tais estudos podem indicar se há ou não risco de contaminação dos habitantes destas áreas, norteando políticas públicas que busquem melhorias na qualidade de vida local. O presente estudo foi realizado com os objetivos de: (i) replicar e validar o protocolo de bioacessibilidade In vitro gastrintestinal para avaliar a bioacessibilidade de As em amostras estratificadas (0-2 e 2-10 cm) de uma área de mineração de ouro em Paracatu (MG); (ii) comparar os teores de As bioacessível com o extraído por Mehlich-1; e, (iii) avaliar a exposição humana aos materiais contaminados com As, considerando um cenário hipotético de máximo risco (ingestão de solo por crianças). Nas dependências da mina aurífera, as áreas amostradas foram: RPPN, B1, Exp. B1, B2, estéril e rejeito. Os teores de As bioacessível (gástrico e gastrintestinal) encontrados no material de referência (NIST 2710) se aproximaram dos valores reportados em outros estudos, validando a reprodução e a aplicação do protocolo. Os menores teores de As total, extraído por Mehlich-1 e bioacessível foram encontrados para a área RPPN. Todas as amostras da área de mineração apresentaram baixos percentuais de As bioacessível. O cálculo da dose de exposição, para o cenário hipotético de risco, indicou que, com exceção do rejeito, os materiais das áreas contribuem, no máximo, pela rota de exposição em questão (ingestão de solo), com 9,5% da entrada de As máxima permitida por dia (0,3 g kg-1 BW dia-1). Correlação entre os teores de As extraído por Mehlich-1 e o bioacessível foi verificada para a fase gástrica, nas duas profundidades de coleta, e gastrintestinal para a profundidade de 2 a 10 cm.
Gold (Au) mining areas are important from the standpoint of economic development, nevertheless soils from these areas are drastically altered by anthropic activities. In addition, the Au-carrying rock material usually contains arsenic (As), a toxic and carcinogenic element. When exposed to the soil surface layer, arsenic undergoes alterations in its chemical form and, or, is transferred to other media (e.g., water, air), being able to enter into the food chain. Involuntary soil ingestion by children is a major route of exposure in As-contaminated soils. Considering the importance of this route of exposure, bioaccessibility tests with As are used with the intent of estimating the contribution of this route in a human health risk assessment. Such studies are useful for estimating risks for people living nearby gold-mining areas and might help decision makers and regulators seeking improvements in public health. The present study aimed at: (i) replicating and validating the In Vitro Gastrointestinal (IVG) bioaccessibility protocol to evaluate the bioaccessibility of As in stratified samples (0-2 and 2 10 cm) of a gold mining area in Paracatu (MG), Brazil; (ii) comparing the bioaccessible levels of As with those extracted by Mehlich-1; and, (iii) evaluating human exposure to As-contaminated materials, considering a hypothetical maximum risk scenario (soil ingestion by children). The selected areas in the gold mine were: reference area = Private Natural Reserve, B1 = mined oxidized soil layer, Exp. B1 = experiment over B1, B2 = mined reduced soil layer, sterile, and pond tailings. The concentrations of bioaccessible As (gastric and gastrointestinal) found in the reference material (NIST 2710) matched those reported in other studies, validating the reproduction and application of the IVG protocol. The lowest total-, Mehlich-1- and bioaccessible-extracted As levels were found for the reference area. All samples of the mining area presented a low percentage of bioaccessible As. The calculated dose of exposure for the hypothetical risk scenario indicated that, except for the pond tailings, in all other areas the exposure route considering soil ingestion contributed at most to 9.5% of the maximum allowed As ingestion per day (0.3 g kg-1 BW day-1). Correlation between As levels extracted by Mehlich-1 and bioaccessible As was verified for the gastric phase, at the two sampling depths, and for the gastrointestinal phase for samples collected at 2 to 10 cm.
Gold (Au) mining areas are important from the standpoint of economic development, nevertheless soils from these areas are drastically altered by anthropic activities. In addition, the Au-carrying rock material usually contains arsenic (As), a toxic and carcinogenic element. When exposed to the soil surface layer, arsenic undergoes alterations in its chemical form and, or, is transferred to other media (e.g., water, air), being able to enter into the food chain. Involuntary soil ingestion by children is a major route of exposure in As-contaminated soils. Considering the importance of this route of exposure, bioaccessibility tests with As are used with the intent of estimating the contribution of this route in a human health risk assessment. Such studies are useful for estimating risks for people living nearby gold-mining areas and might help decision makers and regulators seeking improvements in public health. The present study aimed at: (i) replicating and validating the In Vitro Gastrointestinal (IVG) bioaccessibility protocol to evaluate the bioaccessibility of As in stratified samples (0-2 and 2 10 cm) of a gold mining area in Paracatu (MG), Brazil; (ii) comparing the bioaccessible levels of As with those extracted by Mehlich-1; and, (iii) evaluating human exposure to As-contaminated materials, considering a hypothetical maximum risk scenario (soil ingestion by children). The selected areas in the gold mine were: reference area = Private Natural Reserve, B1 = mined oxidized soil layer, Exp. B1 = experiment over B1, B2 = mined reduced soil layer, sterile, and pond tailings. The concentrations of bioaccessible As (gastric and gastrointestinal) found in the reference material (NIST 2710) matched those reported in other studies, validating the reproduction and application of the IVG protocol. The lowest total-, Mehlich-1- and bioaccessible-extracted As levels were found for the reference area. All samples of the mining area presented a low percentage of bioaccessible As. The calculated dose of exposure for the hypothetical risk scenario indicated that, except for the pond tailings, in all other areas the exposure route considering soil ingestion contributed at most to 9.5% of the maximum allowed As ingestion per day (0.3 g kg-1 BW day-1). Correlation between As levels extracted by Mehlich-1 and bioaccessible As was verified for the gastric phase, at the two sampling depths, and for the gastrointestinal phase for samples collected at 2 to 10 cm.
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ONO, F. B. Bioacessibilidade de arsênio em área de mineração de ouro, Paracatu (MG). 2009. 70 p. Dissertação (Mestrado em Ciência do Solo)-Universidade Federal de Lavras, Lavras, 2009.