Artisanal Gem Mining in Brazil: Evaluation of Oxidative Stress and Genotoxicity Biomarkers.

This study was carried out in the district of Taquaral de Minas, in the municipality of Itinga, located in Jequitinhonha Valley, state of Minas Gerais, which is considered one of the largest yolk-producing regions in Brazil. Miners in gem extraction areas are prone to severe oxidative damage due to their increased exposure to toxic metals, as well as chemical, physical, and biological agents, resulting in diseases such as silicosis. Thus, this work aimed to evaluate occupational exposure in prospectors through biomonitoring techniques using a variety of biomarkers for oxidative stress, genotoxicity, and mutagenicity. Twenty-two miners and seventeen workers who were not occupationally exposed were recruited, totaling thirty-nine participants. The study was approved by the Research Ethics Committee of the Federal University of the Jequitinhonha and Mucuri Valleys. In this study, the levels of total peroxides, catalase activity, and microelements in plasma were evaluated. Additionally, environmental analysis was carried out through the Ames and Allium cepa tests. The results of the lipoperoxidation assessment were significant, with increased frequencies in exposed individuals compared to controls (p < 0.05), as determined by the Mann-Whitney test. Micronutrients in the blood showed lower concentrations in the group exposed to Fe and Se than in individuals not exposed to these elements. The results of the Ames test and Allium cepa test were statistically significant compared to the controls (p < 0.05), as determined by the Mann-Whitney test for genotoxicity and cytotoxicity. Thus, the results of the present study indicate possible environmental contamination and a potential risk to the health of miners, which suggests that further studies are important in the region.

Assessment of Health Risk and Presence of Metals in Water and Fish Samples from Doce River, Brazil, After Fundão Dam Collapse.

The rupture of the Fundão dam released about 50 million m3 of mining tailings in the Doce river basin. To assess the potential for environmental contamination and the risks of residual exposure of the human population generated by these tailings, water and fish samples from the Doce river were collected 25 days after the accident and analyzed the physicochemical parameters of the water and levels of metals by ICP-MS, in addition to the temporal variability of the concentration of these elements through other studies. This was the first study to carry out an assessment of the health risk associated with the consumption of fish contaminated by metals from the areas affected by the disaster. The values of turbidity (5460 NTU), electrical conductivity (74.8 µS cm-1), total dissolved solids (892 mg L-1) and total suspended solids (772 mg L-1) were above the maximum limit allowed by Brazilian legislation, due to the presence of large amounts of solid materials released after the dam rupture. The analysis of metals in water samples indicated high concentrations of Al (1,906.71 µg L-1), Mn (370.32 µg L-1), Fe (8,503.50 µg L-1) and Hg (34.25 µg L-1), while for the fish samples, only As (1,033.98 µg kg-1) and Hg (herbivorous: 505.32 µg kg-1; predatory: 1,184.09 µg kg-1) presented levels above those established by Brazilian legislation. The health risk assessment showed that the estimated daily intake for Hg was higher than the reference dose, reinforcing the need for monitoring the area affected by the disaster.

Arsenic in Mining Areas: Environmental Contamination Routes.

The emission and accumulation of toxic elements such as arsenic in various environmental compartments have become increasingly frequent primarily due to anthropogenic actions such as those observed in agricultural, industrial, and mining activities. An example of environmental arsenic contamination in Brazil exists in the city of Paracatu, MG, due to the operation of a gold mine. The aim of this work is to evaluate the routes and effects of arsenic contamination in environmental compartments (air, water, and soil) and environmental organisms (fish and vegetables) from mining regions as well as the trophic transfer of the element for a risk assessment of the population. In this study, high levels of arsenic were found in the waters of the Rico stream ranging from 4.05 µg/L during the summer season to 72.4 µg/L during the winter season. Moreover, the highest As concentration was 1.668 mg kg-1 in soil samples, which are influenced by seasonal variation and by proximity to the gold mine. Inorganic and organic arsenic species were found above the allowed limit in biological samples, indicating the transfer of arsenic found in the environment and demonstrating a great risk to the population exposed to this area. This study demonstrates the importance of environmental monitoring to diagnose contamination and encourage the search for new interventions and risk assessments for the population.

Iron Oxide Nanomaterials for the Removal of Cr(VI) and Pb(II) from Contaminated River After Mariana Mining Disaster.

If not properly treated, water contaminated with chromium (Cr(VI)) and lead (Pb(II)) can cause severe damage to health due to the accumulation of those toxic metals in the human body. Therefore, in this work, three iron oxides, i.e., δ-FeOOH, cystine-functionalized δ-FeOOH (Cys-δ-FeOOH), and Fe3O4, were synthesized and used as adsorbents for Cr(VI) and Pb(II) in water. The results indicated that the Cr(VI) is best adsorbed on cys-δ-FeOOH followed by δ-FeOOH and Fe3O4. It was because of the enhanced interaction between Cr(VI) and the cysteine functional groups on the δ-FeOOH surface. The Cr(VI) adsorption capacity of cys-δ-FeOOH, δ-FeOOH, and Fe3O4 was 217, 14, and 8 mg g-1, respectively. On the other hand, Pb(II) was preferentially adsorbed directly on δ-FeOOH achieving a maximum Pb(II) adsorption capacity of 174 mg g-1. The Pb(II) adsorption capacity of cys-δ-FeOOH and Fe3O4 was 97 and 74 mg g-1, respectively. The Cr(VI) adsorption on cys-δ-FeOOH was best described by the Langmuir-Freundlich model, whereas Pb(II) adsorption on δ-FeOOH followed the Langmuir model. Both Cr(VI) and Pb(II) adsorption on the adsorbents was well-fitted to pseudo-second-order kinetics. The Cr(VI) was more quickly adsorbed by cys-δ-FeOOH (h0 = 0.10 mg g-1 min-1) while the initial adsorption rate of Pb(II) onto δ-FeOOH was significantly faster (h0 = 16.34 mg g-1 min-1). Finally, the synthesized adsorbents were efficient to remove Cr(VI) and Pb(II) from water samples of the Doce river after the environmental disaster of Mariana city, Brazil, thus showing its applicability to remediate real water samples.

Removal of mercury(II) from contaminated water by gold-functionalised Fe3O4 magnetic nanoparticles.

Fe3O4 nanoparticles were prepared by co-precipitation of Fe2+ and Fe3+ and then modified with Au to produce an effective adsorbent (Fe3O4/Au) for aqueous Hg(II) in contaminated water. Rietveld refinement on the XRD pattern confirmed that the Fe3O4/Au was synthesised. Mössbauer spectra exhibited broad and asymmetric resonance lines with two sextets which can be assigned to tetrahedral Fe3+; and octahedral Fe3+/Fe2+. The quantitative analysis of magnetite confirms that the sample shows around 3 wt.% Au and 97 wt.% partially oxidised Fe3O4. High surface area: 121 m2 g-1, average pore sizes: 6.3 nm and pore volume: 1.64 cm3 g-1. The kinetics data were better fitted with a pseudo-second-order and Dubinin-Radushkevich isotherm suggests the Hg(II) adsorption onto Fe3O4/Au nanoparticles was mainly by chemical adsorption forming complex with the Au metal immobilised on Fe3O4 surfaces. Adsorption capacity of 79.59 mg g-1. Ionic strength and co-existing ions had a slight influence on the adsorption capacity.

Contamination in a brazilian river: a risk of exposure to untreated effluents.

Due to natural or anthropogenic activities, various chemical contaminants, such as toxic metals and organic compounds, enter water systems and can have multiple deleterious effects on many living organisms. The Todos os Santos River (TSR) in Brazil receives a high discharge of untreated effluents from various sources. The purpose of this study was to determine trace element concentrations in water samples from the TSR, evaluate the toxicological effects of these elements by using the (onion) test, and verify the physical-chemical parameters to establish the risk of exposure related to the contaminated river. The samples were taken in 2011 at six selected points (two upstream of an urban area, two in the urban area, and two downstream of the urban area) with physical-chemical parameters evaluated. The concentrations of Al (21.63-1688.84 µg L), P (38.59-1760.87 µg L), and Fe (478.9-8296.3 µg L) were above the maximum levels permitted under Brazilian law (and the World Health Organization); little dissolved O was observed. Based on the test, genotoxic and mutagenic effects may occur in the river and could be due to anthropogenic increases in metal content. These important results have serious implications for the ecosystem as well as the health of the people who use the water.