Arsenic occurrence in Brazil and human exposure

Effects of biochar on soil contaminated by metals and metalloids from slag disposal of an old environmental liability in Ribeira Valley, Brazil

Contamination with potentially toxic metals and metalloids (PTMs) in mining areas poses significant environment and human health risks. Using biochar as an amendment can be a cost-effective and eco-friendly method to reduce PTM bioavailability in contaminated soils, thus lowering plant uptake. This study investigated biochar derived from the organic fraction of municipal solid waste (OFMSW) at three pyrolysis temperatures (300, 500, and 700 °C) and two application rates (1% and 5%, w/w) for the remediation of slag-contaminated soils from an old environmental liability in the Ribeira Valley (Brazil). The results showed Zn > Pb > Cu > As > Co > Cr > Cd > Ni pseudo-total concentrations in slag with concentrations of As, Cu, Pb, and Cd posing greater environmental risks due to their toxicity. The biochar addition exerted limited effects on chemical fractionation, likely due to soil alkalinity, and BC300 5% increased As availability. A 1% biochar addition improved maize (Zea mays) growth, whereas 5% BC500 and BC700 were phytotoxic. The highest bioconcentration factor (BCF) values were observed for Cr, Cu, Ni, and Zn, which are all essential nutrients for plants; however, translocation factor (TF) from roots to shoots was generally low. A combination of BCF and TF < 1 suggested mechanisms limiting PTM uptake and translocation in plants. Pb showed a high ecological risk potential (Eri), with hazard quotients (HQ) exceeding 1 for the slag. BC700 5% provided the most promising Eri for As, Pb, and Zn; however, it proved toxic to maize, highlighting the need for multidisciplinary research and biochar's potential in site remediation. Further treatments are necessary for enhancing the retention efficiency or exploring combinations with other organic or inorganic amendments.

Subchronic intake of arsenic at environmentally relevant concentrations causes histological lesions and oxidative stress in the prostate of adult Wistar rats

The prostate gland is one of the main sites of hyperplasia and cancer in elderly men. Numerous factors have been demonstrated to disrupt prostate homeostasis, including exposure to environmental pollutants. Arsenic is a metalloid found ubiquitously in soil, air, and water, which favors human poisoning through the involuntary intake of contaminated drinking water and food and has harmful effects by increasing the oxidative stress response. This study aimed to investigate the effects of prolonged exposure to arsenic at environmentally relevant concentrations on the prostate biology of adult Wistar rats. Thirty 80-day-old male rats were divided into three experimental groups. Rats from the control group received filtered water, whereas animals from the arsenic groups ingested 1 mg L-1 and 10 mg L-1 of arsenic, in the form of sodium arsenite, daily. The arsenic solutions were provided ad libitum in the drinking water for eight weeks. Our results showed that 1 mg L-1 and 10 mg L-1 of arsenic made the prostate susceptible to evolving benign and premalignant histopathological changes. While the ingestion of 1 mg L-1 of arsenic reduced SOD activity only, 10 mg L-1 diminished SOD and CAT activity in the prostate tissue, culminating in high MDA production. These doses, however, did not affect the intraprostatic levels of DHT and estradiol. In conclusion, exposure to arsenic at environmentally relevant concentrations through drinking water induces histological and oxidative stress-related changes in the prostate of adult rats, strengthening the between arsenic exposure and prostate disorders.

Seasonal arsenic in catfish (Siluriformes, Ariidae) and the hydrochemical conditions of two areas in a Ramsar site on the Brazilian coast

The construction of a data bank concerning metal and metalloid content of bioindicator fish from coastal areas is very important as it can help environmental managers in decision making. In natural conditions, the concentration of elements can be influenced by abiotic parameters such as water salinity. In this study, catfish Cathorops spixii were evaluated concerning the total arsenic (As) concentration in the muscle tissues of individuals subjected to different abiotic conditions in the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC), which was recently included on the Ramsar list of wetlands of international importance. Seventy-four catfish were seasonally caught in the northern and southern regions of the CIELC and their hydrochemical parameters were obtained. C. spixii from the southern, best preserved, area showed arsenic concentrations around ten times higher than the maximum limit established for fish intended for human consumption. However, these high concentrations of arsenic could be associated with the abiotic parameters of the water, such as salinity variations, in this area.

Structural, Optical, and Arsenic Removal Properties of Sol-Gel Synthesized Fe-Doped TiO2 Nanoparticles

Pure and Fe-doped TiO₂ nanoparticles were synthesized by the sol-gel method. The samples were characterized by X-ray diffraction, Raman spectroscopy, BET, UV-vis diffuse reflectance spectroscopy, and scanning electron microscopy. The results show a dependence between the crystallite size and the amount of dopant, which decreases from 13.02 to 12.81 nm. The same behavior was observed in the optical properties, where the band gap decreased from 3.2 to 2.86 eV. The arsenic (V) adsorption was tested in aqueous solution containing 5 mg/L of arsenic and 0.5 g/L of adsorbent at pH 7 and in dark conditions. The results indicate that the TiO₂-B sample shows a higher arsenic removal, reaching 88% arsenic removal from the water at pH 7. Thus, it is also shown that the best performance occurs at pH 5, where it reaches an arsenic removal of 94%. Ion competition studies show that arsenic removal capacity is slightly affected by chloride, carbonate, nitrate, and sulfate ions. According to the results, the synthesized samples are a promising material for treating arsenic-contaminated water.

Soil-sediment linkage and trace element contamination in forested/deforested areas of the Itacaiúnas River Watershed, Brazil: To what extent land-use change plays a role?

Trace elements (TE) contamination in forested areas of the Itacaiúnas River Watershed (IRW), Brazilian Amazon, arouses growing interest owing to the rapid deforestation and mining activities. In this study, soils (surface, SS; bottom, BS) and stream sediments (SD) from forested/deforested areas of IRW were analyzed with the aim of (1) evaluating the major sources of TE (mainly As, Ba, Cd, Cu, Co, Cr, Hg, Mo, Mn, Ni, Pb, V, and Zn), and (2) examining the soil-sediment TE link related to land-use change and/or geologic factors. Compositional data analysis (CoDA) was used to eliminate data closure issues and the centred log-ratio (clr) transformation yielded better results in Principal Component Analysis (PCA). The TE distribution pattern was significantly different (p < 0.05) between forested and deforested areas, but in both areas the TE distribution pattern is significantly correlated between SS, BS, and SD, indicating a strong lithogenic control. PCA (clr-transformed) identified the major geochemical bedrock signature as Fe-Ti-V-Cu-Cr-Ni, which is nearly similar in soil and sediments. The more accentuated enrichment and the maximum number of anomalies of these elements were found in the Carajás Basin and are highly coincident with mineral deposits/local lithologies without clear indication of anthropogenic contamination from point sources. Besides geogenic factors, deforestation is also affecting TE distribution in the basin. In deforested areas, Mn was significantly enriched in the surface horizon. Furthermore, linear regression analysis shows stronger TE relationships between soils and sediments in deforested areas than in forested ones, reflecting higher erosion in the former. This could be the reason for the relatively higher enrichment of TE (e.g., Fe, Mn, Cu, Cr, Ni) in deforested sediments. The TE contamination using regional background values provides more accurate results than worldwide reference values. Thus, the former should be considered for a more realistic environmental risk assessment in IRW and other forest ecosystems in the Brazilian Amazon.

Advances in As contamination and adsorption in soil for effective management

Arsenic (As) is a heavy metal that causes widespread contamination and toxicity in the soil environment. This article reviewed the levels of As contamination in soils worldwide, and evaluated how soil properties (pH, clay mineral, organic matter, texture) and environmental conditions (ionic strength, anions, bacteria) affected the adsorption of As species on soils. The application of the adsorption isotherm models for estimating the adsorption capacities of As(III) and As(V) on soils was assessed. The results indicated that As concentrations in contaminated soil varying significantly from 1 mg/kg to 116,000 mg/kg, with the highest concentrations being reported in Mexico with mining being the dominating source. Regarding the controlling factors of As adsorption, soil pH, clay mineral and texture had demonstrated the most significant impacts. Both Langmuir and Freundlich isotherm models can be well fitted with As(III) and As(V) adsorption on soils. The Langmuir adsorption capacity varied in the range of 22-42400 mg/kg for As(V), which is greater than 45-8901 mg/kg for As(III). The research findings have enhanced our knowledge of As contamination in soil and its underlying controls, which are critical for the effective management and remediation of As-contaminated soil.

Seven potential sources of arsenic pollution in Latin America and their environmental and health impacts

This review presents a holistic overview of the occurrence, mobilization, and pathways of arsenic (As) from predominantly geogenic sources into different near-surface environmental compartments, together with the respective reported or potential impacts on human health in Latin America. The main sources and pathways of As pollution in this region include: (i) volcanism and geothermalism: (a) volcanic rocks, fluids (e.g., gases) and ash, including large-scale transport of the latter through different mechanisms, (b) geothermal fluids and their exploitation; (ii) natural lixiviation and accelerated mobilization from (mostly sulfidic) metal ore deposits by mining and related activities; (iii) coal deposits and their exploitation; (iv) hydrocarbon reservoirs and co-produced water during exploitation; (v) solute and sediment transport through rivers to the sea; (vi) atmospheric As (dust and aerosol); and (vii) As exposure through geophagy and involuntary ingestion. The two most important and well-recognized sources and mechanisms for As release into the Latin American population's environments are: (i) volcanism and geothermalism, and (ii) strongly accelerated As release from geogenic sources by mining and related activities. Several new analyses from As-endemic areas of Latin America emphasize that As-related mortality and morbidity continue to rise even after decadal efforts towards lowering As exposure. Several public health regulatory institutions have classified As and its compounds as carcinogenic chemicals, as As uptake can affect several organ systems, viz. dermal, gastrointestinal, peptic, neurological, respiratory, reproductive, following exposure. Accordingly, ingesting large amounts of As can damage the stomach, kidneys, liver, heart, and nervous system; and, in severe cases, may cause death. Moreover, breathing air with high As levels can cause lung damage, shortness of breath, chest pain, and cough. Further, As compounds, being corrosive, can also cause skin lesions or damage eyes, and long-term exposure to As can lead to cancer development in several organs.

Developing a biosurfactant to attenuate arsenic contamination in mining tailings

The present study aimed to investigate the ability of a microbial consortium to produce biosurfactant in the presence of two carbon sources and also to evaluate the efficiency of the cell-free supernatant cultures to mobilize As from naturally contaminated soil. Pseudomonas and Stenotrophomonas were the main microorganisms in the microbial consortium. The pH, the incubation time, the temperature, and the glucose and glycerol ratios in the culture medium are the main factors influencing biosurfactant production. The lowest surface tension, 30 mN.m-1, and the higher emulsification index, 58%, were achieved at the optimum production conditions (OPC), i.e., pH 9.5, a 2.5 glucose/glycerol ratio, after three days of incubation at 25 °C. The cell-free extracts containing biosurfactants were more efficient in mobilizing As than distilled water, CaCl2 0.1 mol.L-1; saponin, 0.1%; or sodium dodecyl sulfate, 1% during a sequential soil-flushing procedure. The As mobilization using the supernatants containing biosurfactant was sensitive to pH. The use of OPC cell-free supernatant under alkaline conditions leads to the best-obtained results: 24.6% of As removal (678 mg.kg-1) during sequential extractions. The toxicity reduction of the column eluted solution from the first to the seventh cycle evaluated by the germination index (GI) and morphological structures of Allium cepa in the ecotoxicological assessment confirmed the efficiency of the proposed treatment. Allium cepa seeds and seedlings were sensitive in detecting As in soil and eluted solutions with short time responses to the contaminant. Seeds development increased gradually with arsenic removal. The germination index rose from 0 to 55% after soil decontamination through the proposed soil-flushing procedure.

Arsenic contamination assessment in Brazil - Past, present and future concerns: A historical and critical review

This paper presents a summary of some relevant documents published during the last decades regarding arsenic contamination in Brazil until December 2018, including scientific papers, reports and regulatory documents. Natural and anthropogenic arsenic sources were covered, excluding those related to agriculture. International "key" documents related to arsenic contamination were used to support the discussion and comparative analysis. This paper aims: (a) to summarize and discuss some available data (including Portuguese written documents) concerning arsenic contamination in Brazil, mainly geographical, geological, geochemical, environmental and health studies; (b) to critically review the published studies comparing their main findings; (c) to describe and compare ancient and recent contamination events; and (d) to highlight key knowledge gaps, and identify promising areas for future researches. The arsenic contamination scenario in Brazil results not only from mining. Natural or anthropogenic emissions caused by great magnitude phenomena as flooding, erosion, landslide and, water scarcity equally impact arsenic mobilization/immobilization equilibria. Our literature review demonstrates that arsenic contamination of soils, sediments and water sources is observed at least at three of the five geographically defined Brazilian regions (Northern, Southern and, Southeastern regions). Arsenic enriched soils, and waters naturally occur all around the country and anthropogenic activities have been the main contributory factor to the environmental contamination since the 18th Century. Geogenic materials (topsoil and mining tailings), and water samples could contain extremely high arsenic concentrations, i.e. 21,000 mg kg^-1 or 1,700,000 μg L^-1, respectively, have been found mainly at the "Iron Quadrangle". Moreover, if we consider both the Brazilian and international parameters, the health risks associated with the human exposition to arsenic are of significant concern. For those reasons, constant monitoring of As contaminated areas in Brazil is mandatory. Furthermore, it is necessary to learn from the mistakes made in the past in order to prevent or minimize future problems.

Arsenic induces dose-dependent structural and ultrastructural pathological remodeling in the heart of Wistar rats

AIM

Arsenic, an environmental contaminant, represents a public health problem worldwide. Studies have shown its association with molecular mechanisms related to cardiomyocytes redox balance. However, the microstructure and ultrastructure of cardiac tissue, as well as the activity of its antioxidant defenses front of disturbances in the mineral bioavailability induced by arsenic are still scarce. Thus, the aim of this study was to evaluate if arsenic exposure might induce structural and ultrastructural damages in cardiac tissue, including pathological remodeling of the parenchyma and stroma. Moreover, its impact on micromineral distribution and antioxidant enzymes activity in heart tissue was also evaluated.

MAIN METHODS

Adult male Wistar rats were divided into three groups that received 0, 1 and 10 mg/L sodium arsenite in drinking water for eight weeks. The hearts were collected and subjected to structural and ultrastructural analysis, mineral microanalysis and antioxidant enzymes quantification. Functional markers of cardiac damages were evaluated using serum samples.

KEY FINDINGS

Arsenic exposure induced dose-dependent structural and ultrastructural remodeling of cardiac tissue, with parenchyma loss, increase of stroma components, collagen deposition, and pathological damages such as inflammation, sarcomere disorganization, mitochondria degeneration and myofilament dissociation. Moreover, this metalloid was bioaccumulated in the tissue affecting its micromineral content, which resulted in antioxidant imbalance and increased levels of oxidative stress and cardiac markers.

SIGNIFICANCE

Taken together, our findings indicate that the heart is a potential target to arsenic toxicity, and long-term exposure to this metalloid must be avoided, once it might induce several cardiac tissue pathologies.

Modeling arsenic content in Brazilian soils: What is relevant?

Arsenic accumulation in the environment poses ecological and human health risks. A greater knowledge about soil total As content variability and its main drivers is strategic for maintaining soil security, helping public policies and environmental surveys. Considering the poor history of As studies in Brazil at the country's geographical scale, this work aimed to generate predictive models of topsoil As content using machine learning (ML) algorithms based on several environmental covariables representing soil forming factors, ranking their importance as explanatory covariables and for feeding group analysis. An unprecedented databank based on laboratory analyses (including rare earth elements), proximal and remote sensing, geographical information system operations, and pedological information were surveyed. The median soil As content ranged from 0.14 to 41.1 mg kg^-1 in reference soils, and 0.28 to 58.3 mg kg^-1 in agricultural soils. Recursive Feature Elimination Random Forest outperformed other ML algorithms, ranking as most important environmental covariables: temperature, soil organic carbon (SOC), clay, sand, and TiO₂. Four natural groups were statistically suggested (As content ± standard error in mg kg^-1): G1) with coarser texture, lower SOC, higher temperatures, and the lowest TiO₂ contents, has the lowest As content (2.24 ± 0.50), accomplishing different environmental conditions; G2) organic soils located in floodplains, medium TiO₂ and temperature, whose As content (3.78 ± 2.05) is slightly higher than G1, but lower than G3 and G4; G3) medium contents of As (7.14 ± 1.30), texture, SOC, TiO₂, and temperature, representing the largest number of points widespread throughout Brazil; G4) the largest contents of As (11.97 ± 1.62), SOC, and TiO₂, and the lowest sand content, with points located mainly across Southeastern Brazil with milder temperature. In the absence of soil As content, a common scenario in Brazil and in many Latin American countries, such natural groups could work as environmental indicators.

Assessing the most sensitive and reliable endpoints in plant growth tests to improve arsenic risk assessment

Arsenic (As) is toxic to humans and the environment. Its toxicity has been assessed in many ways, including plant growth tests integrated in As risk assessments (RA). The tiered approach used in RA schemes assumes that lower tiers are more conservative than higher tiers. Plant growth tests may comprise lower tier of a RA and include the measurement of several endpoints. However, only few of these endpoints are highly sensitive and reliable, which makes them more appropriate to comprise lower tiers. Therefore, the selection of those endpoints is needed. The present study aimed to evaluate the most appropriate endpoints of plant growth tests to use in lower tier As RA schemes. This selection of endpoints was based on their sensitivity and reliability, using different tropical soils and plant species. In order to achieve this objective, six plant species were exposed to eight levels of As contamination (0; 8; 14.5; 26; 46.5; 84; 150; 270 mg kg^-1), in three different tropical soils (Oxisol, Inceptisol, and tropical artificial soil). The endpoints measured were: first germination count (FrC), plant height (PH), relative leaf area (RLA), stem diameter (SD), total germination (TG), germination speed index (GSI), dry mass (DM), number of completely expanded leaves (CEL), plant survival (PS), soil plant analysis development chlorophyll level (SPAD), and the final germination count (FnC). Toxic values for 50% of effect were estimated for each endpoint within each species and test soil, to rank them according to their sensitivity and reliability. The most sensitive endpoints were: FrC, RLA, DM, GSI, PH, and FnC, while the most reliable endpoints were: FrC, DM, GSI, DM, PH, FnC, and TG. Our findings suggest that FrC, DM, GSI, PH, and FnC are the most adequate endpoints to be used in plant growth tests as lower tiers of As RA in tropical regions.

Emerging technologies for arsenic removal from drinking water in rural and peri-urban areas: Methods, experience from, and options for Latin America

Providing drinking water with safe arsenic levels in Latin American (LA) countries (a total of 22 countries) is a major current challenge. Arsenic's presence in water has been neglected for many decades since it was first reported ~100 years ago in Argentina. The major arsenic source in this region is geogenic. So far, arsenic has been reported in 15 LA countries. Arsenic concentrations in drinking water have been reported up to >200 fold (2000 μg/L) the WHO limit of 10 μg/L. About 14 million people in the arsenic affected LA countries depend on contaminated water characterized by >10 μg/L of arsenic. Low-cost, easy to use, efficient, and sustainable solutions are needed to supply arsenic safe water to the rural and peri-urban population in the affected areas. In the present study, >250 research articles published on various emerging technologies used for arsenic remediation in rural and peri-urban areas of LA countries are critically reviewed. Special attention has been given to arsenic adsorption methods. The manuscript focuses on providing insights into low cost emergent adsorbents with an implementation potential in Latin America. Natural, modified and synthetic adsorbents used for arsenic decontamination were reviewed and compared. Advantages and disadvantages of treatment methods are summarized. Adsorbent selection criteria are developed. Recommendations concerning emerging adsorbents for aqueous arsenic removal in LA countries have also been made.

Arsenic Exposure and Effects in Humans: A Mini-Review in Brazil

Arsenic (As) is widely studied in several countries due to its toxicity to biota in the environment. Arsenic sources may be natural or anthropogenic, and the mobility of the element is ruled by physicochemical conditions that also define the dominant As species in the environment. Arsenic levels are evaluated in various abiotic and biotic environmental samples. The highest As levels are observed in sediment, from where it may be mobilized into the aquifers. This article reviews studies about As in the world but with emphasis on studies performed in Brazil, a country where continental water bodies are a common geographic feature. We reviewed 64 studies published between 1985 and 2016. The results indicate that in recent years more studies have been conducted to determine As levels in foods and human samples as a tool to evaluate the exposure of populations and identify potential sources. In Brazil, the main problems associated with contamination with As are the use of wood preservatives and herbicides as well as the impact caused by mining. Also, the precarious character of sewage treatment systems contributes to the contamination of water bodies.

Analysis of the association between bladder carcinoma and arsenic concentration in soil and water in southeast Brazil

In approximately 50% of cases of bladder carcinoma, an associated predisposing factor can be established. The main factors are exposure to tobacco, arsenic (As) ore and aromatic compounds. Arsenic is a metalloid with a low average concentration in the earth's crust, and one of the most dangerous substances for human health. The present study aims to evaluate the incidence of hospitalization and mortality from bladder neoplasia and its possible association with As concentration in water and soil in two of the most critical regions of Brazil: the states of São Paulo and Minas Gerais. We have investigated bladder cancer hospitalization and mortality in the states of São Paulo and Minas Gerais during 2010-2014. Water and soil samples were analyzed and As concentrations were established. Data were obtained through the Department of Informatics of the Brazilian Unified Health System. Correlation was made with water samples from São Paulo and with data on soil analysis from Minas Gerais. The results revealed no direct association in the distinctive municipalities. Areas with high environmental As concentration had a low bladder cancer rate, while areas with normal as levels had similar cancer rates. The quantitative variables did not present a normal distribution (p < 0.05). In conclusion, we did not observe a correlation between as concentration in water or soil and bladder cancer's hospitalization and mortality rates in the states of São Paulo and Minas Gerais.

A meta-analysis of the distribution, sources and health risks of arsenic-contaminated groundwater in Pakistan

Globally, millions of people who rely on groundwater for potable purposes and agriculture have been inadvertently exposed to toxic arsenic (As) because of its natural occurrence in groundwater in several countries of Asia, Europe and America. While the presence of As in groundwater and its impacts on human health have been documented in many countries, there is little information on As contamination in Pakistan. This review highlights, for the first time, the extent and severity of As-induced problems in Pakistan based on relevant published papers; discusses possible sources of As contamination of aquifers; and estimates As-induced potential health hazards in the country in relation to global data. Data from 43 studies (>9882 groundwater samples) were used to describe As variability in groundwater of Pakistan and for comparison with global data. The mean groundwater As content reported in these studies was 120 μg/L (range: 0.1-2090 μg/L; SD: ±307). About 73% of the values for mean As contents in the 43 studies were higher than the World Health Organization (WHO) permissible limit (10 μg/L) for drinking water, while 41% were higher than the permissible limit of As in Pakistan (50 μg/L). It was observed that groundwater samples in some areas of Punjab and Sindh provinces contained high As concentrations which were almost equal to concentrations reported in the most contaminated areas of the world. We predicted that the mean values of ADD, HQ and CR were 4.4 μg kg^-1day^-1 (range: 0-77 μg kg^-1day^-1), 14.7 (range: 0-256) and 0.0029 (range: 0-0.0512), respectively, based on mean As concentrations reported in Pakistan. In addition, this article proposes some integrated sustainable solutions and future perspectives keeping in view the regional and global context, as well as the on-ground reality of the population drinking As-contaminated water, planning issues, awareness among civil society and role of the government bodies. Based on available data, it is predicted that almost 47 million people in Pakistan are residing in areas where more than 50% of groundwater wells contain As concentrations above the WHO recommended limit of As in drinking water.

Arsenic aggravates oxidative stress causing hepatic alterations and inflammation in diabetic rats

AIMS

Studies have shown that exposure to either environmental toxicants or hyperglycemia causes hepatic injuries. However, it is unclear the extent to which their combined exposure may influence liver functions. Therefore, we aimed to evaluate morphological and functional hepatic parameters in diabetic rats exposed to arsenic.

METHODS

Diabetes was induced in male rats by intraperitoneal streptozotocin injection. While healthy and diabetic animals received saline solution (negative control and diabetes control, respectively), other animals received 10 mg/L sodium arsenate (arsenic control and diabetes + arsenic groups, respectively) for 40 days in drinking water. Liver tissue was subjected to antioxidant enzymes analysis, cytokine assay, arsenic determination, and histopathological evaluation. Functional markers of hepatic damage were analyzed using serum samples.

KEY FINDINGS

Arsenate exposure reduced the antioxidant enzymes activity in healthy rats, and it worsened the reduction of GST in diabetic animals. Consequently, arsenate-exposed animals showed increased malondialdehyde and carbonyl protein levels, being this increase worsened in diabetes + arsenic animals. Arsenate-exposed groups also showed hepatic inflammatory process with high number of mast cells and TNF-α production mainly in diabetes + arsenic animals. Vascular alterations, such as congestion, bleeding, and hemosiderin deposition were intensified in diabetes + arsenic animals, whereas glycogen storage reduced in these animals.

SIGNIFICANCE

We concluded that arsenate exposure was able to intensify morphological and functional damages in liver tissue of diabetic animals.

Metals and arsenic in fish from a Ramsar site under past and present human pressures: Consumption risk factors to the local population

The risk of metals and As in seafood for traditional populations living in a Marine Protected Areas (MPA) is seldom assessed, although the risk of human exposure to contaminants is one of the indicators associated with the socioeconomic goals of MPAs. The current study aimed to estimate the potential risk of some metals (Cd, Pb, and Zn) and arsenic (As) for human health through the ingestion of fish locally harvested in a Ramsar site, the Cananéia-Iguape-Peruíbe Environmental Protected Area (APA-CIP). Previous studies showed environmental impacts in this area due to former mining activities and urbanization. Cathorops spixii, a catfish largely consumed by the local population, was collected along the estuary in three seasons with different rain regimes. Metals and As loads in muscle tissue were quantified and it was estimated (i) the target hazard quotient (THQ) and (ii) the daily intake (EDI) for metals and As, (iii) the cancer risk (CRisk) only for As, and (iv) the number of eligible meals per month. Cd, Pb, and As were found at concentrations above action levels for human consumption. Depending on the level of exposure of the local population, the consumption of C. spixii may pose risk to human health. Highest THQs were estimated for fish collected in sites closer to the main contamination sources in the APA-CIP, i.e. the mouth of Ribeira de Iguape River (P1) and the city of Cananéia (P4, P5, and P6). Arsenic showed high levels of cancer risk, although restricted to the area close to the city. The exposure of the local population to metal and As contaminated seafood cannot be disregarded in environmental studies and management of the APA-CIP.

Effects of Arsenic Compounds on Microminerals Content and Antioxidant Enzyme Activities in Rat Liver

Interactions of arsenic with essential trace elements may result in disturbances on body homeostasis. In the present study, we aimed to investigate the effects of different arsenic compounds on micromineral content and antioxidant enzyme activities in rat liver. Male Wistar rats were randomly divided into five groups and exposed to sodium arsenite and sodium arsenate at 0.01 and 10 mg/L for 8 weeks in drinking water. The concentration of arsenic increased in the liver of all arsenic-exposed animals. The proportion of zinc and copper increased in animals exposed to 0.01 mg/L sodium arsenite. In addition, these animals presented a reduction in magnesium and sodium content. Superoxide dismutase activity decreased mainly in arsenite-exposed animals, whereas catalase activity decreased in animals exposed to 10 mg/L sodium arsenate. Further, exposure to sodium arsenate at 10 mg/L altered copper and magnesium content in the liver, and reduced total protein levels. Overall, both arsenic compounds altered the liver histology, with reduction in the proportion of cytoplasm and hepatocyte, and increased the percentage of sinusoidal capillaries and macrophages. In conclusion, our findings showed that oral exposure to arsenic compounds disturbs the trace elements balance in the liver, especially at low concentration, altering enzymatic and stereological parameters. We concluded that despite the increase in trace elements content, the antioxidant enzyme activities were downregulated and did not prevent morphological alterations in the liver of animals exposed to both arsenic compounds.

The environmental impacts of one of the largest tailing dam failures worldwide

The impacts of the SAMARCO iron tailing spill along more than 650 km, between the dam and the plume of the Doce River in the Atlantic, were assessed by the determination of toxic metals. The tailing spill caused a substantial increase in suspended sediment loads (up to 33,000 mg L⁻¹), in addition to large depositions of waste along the Doce basin. The highest estimated transport of dissolved metals was observed for Fe (58.8 μg s⁻¹), Ba (37.9 μg s⁻¹) and Al (25.0 μg s⁻¹). Sediments reached the highest enrichment factors (EFs) for Hg (4,234), Co (133), Fe (43), and Ni (16), whereas As (55), Ba (64), Cr (16), Cu (17), Mn (41), Pb (38) and Zn (82) highest EFs were observed for suspended particulate matter (SPM). Iron, As, Hg, Mn exceeded sediment quality guidelines. Therefore, the risk of occurrence of adverse effects is highly possible, not only due to the dam failure, but also due to the Fe mining and the artisan Au mining. Heavy rain episodes will likely cause enhanced erosion, remobilization, and transport of contaminated particles, sustaining high inputs of SPM and metals for the years to come and threatening the ecosystem services.

Effects of Sodium Arsenite and Arsenate in Testicular Histomorphometry and Antioxidants Enzymes Activities in Rats

The main source of environmental arsenic exposure in most countries of the world is drinking water in which inorganic forms of arsenic predominate. The present study was aimed to test the impact of two different compounds of inorganic arsenic in histomorphometric and enzymatic parameters in the testes by oral exposition. Adult Wistar male rats were exposed to sodium arsenite and arsenate in drinking water, testing for each chemical form the concentrations of 0.01 and 10 mg/L per 56 days. The animals intoxicated with arsenic, mainly sodium arsenite, showed reduction in the percentage of seminiferous epithelium and in proportion and volume of Leydig cells. Moreover, there was an increase in the percentage of tunica propria, lumen, lymphatic space, blood vessels, and macrophages. The activity of superoxide dismutase (SOD) did not change among the groups. However, the activity of catalase (CAT) decreased in animals exposed to both arsenic compounds. In addition, the higher concentration of arsenic, mainly as sodium arsenite, caused vacuolization in the seminiferous epithelium. The body and testes weight as well as testosterone concentration remained unchanged among the groups. In conclusion, exposition to arsenic, mainly as sodium arsenite, caused alteration in histomorphometric parameters and antioxidant defense system in the testes.

Hydrogeochemistry of arsenic pollution in watersheds influenced by gold mining activities in Paracatu (Minas Gerais State, Brazil)

The aim of this study is to evaluate total arsenic (As) concentrations in drinking water (main pathway of human exposure) and its hydrogeochemical controls in the "Morro do Ouro" gold mine region, which is the largest gold mine in Brazil, characterized by gold-arsenopyrite association. Arsenic concentration was generally below the detection limit (LOD < 0.5 μg L(-1)). Thus, water ingestion may not be a significant exposure pathway to local population. Low groundwater As concentrations (<1 μg L(-1)) are likely due to ore body structural setting, which plunges from 10° to >20°, being readily covered by thick phyllites that are poor in As some hundreds of meters away from the mine. Thirty-five percent of As levels in superficial waters (<0.5 to 40 μg L(-1)) were >10 μg L(-1), which is the maximum permissible value for human ingestion. The highest concentrations were found nearby mine facilities and old artisanal mining areas surrounding the mine, decreasing downstream. Undisturbed watersheds showed As concentrations close to LOD. Hydrogeochemical data stress the sorption (adsorption and co-precipitation) of As role, mainly by Fe oxyhydroxides, as a geochemical filter that retains As, attenuating its concentration in both superficial and groundwater. Such minerals are abundant in the region oxisols, sediments, and phyllites and may form stable mineral complexes with As under the pH (mostly neutral) and Eh (reduced environment) conditions found in the field. It has been demonstrated that As(III) (more toxic) and As(V) co-exist in the analyzed waters and that As(V) predominates in superficial water.

Interaction of arsenic species with tropical river aquatic humic substances enriched with aluminum and iron

The mobility and bioavailability of arsenic (As) are strongly controlled by adsorption/precipitation processes involving metal oxides. However, the organic matter present in the environment, in combination with these oxides, can also play an important role in the cycle of arsenic. This work concerns the interaction between As and two samples of aquatic humic substances (AHS) from tropical rivers. The AHS were extracted as proposed by IHSS, and were characterized by (13)C NMR. The experiments were conducted with the AHS in natura and enriched with metal cations, with different concentrations of As, and complexation capacity was evaluated at three different pH levels (5.0, 7.0, and 9.0). The AHS samples showed similar chemical compositions. The results suggested that there was no interaction between As(III) and AHS in natura or enriched with Al. Low concentrations of As(V) were bound to AHS in natura. For As(III), the complexation capacity of the AHS enriched with Fe was approximately 48 μmol per g of C, while the values for As(V) were in the range 69-80 μmol per grams of C. Fluorescence spectra showed that changes in Eh affected the complexation reactions of As(V) species with AHS.

Simultaneous photooxidation and sorptive removal of As(III) by TiO2 supported layered double hydroxide

The present study focused on the enhanced removal of As(III) by the simultaneous photooxidation and removal process using TiO2 nanoparticles supported layered double hydroxide (TiO2/LDH). The TiO2/LDH nanocomposites were synthesized using a flocculation method, and nanosized (30-50 nm) TiO2 particles were well-distributed on the LDH surface. The XPS and DLS data revealed that the TiO2/LDH nanocomposites were both chemically and physically stable in the aquatic system. The optimum ratio of TiO2 was 20 wt.% and the calcination process of LDH enhanced the removal capacity of As(III) by the reconstruction process. In the kinetic removal experiment, UV irradiation improved the removal rate of As(III), based on the continuous conversion of As(III) to As(V), and that the removal rate was faster under alkaline conditions than acidic and neutral conditions due to the abundance of oxidants and negative charged As(III) species (pKa: 9.2). The main mechanism of As(III) photooxidation is the direct oxidation by [Formula: see text] , which is generated by supported TiO2 nanoparticles. X-ray near edge structure results also confirmed that the As(III) was completely oxidized to As(V). Consequently, the simultaneous photooxidation and removal process of As(III) by TiO2/LDH nanocomposites may be the effective removal option in As(III) contaminated water.

Chronic arsenic toxicity in sheep of Kurdistan province, western Iran

After the detection of arsenic (As) toxicity in sheep from Ebrahim-abad and Babanazar villages in Kurdistan province, the concentration of this element in drinking water, cultivated soil, alfalfa hay, wool, and blood samples was evaluated. Total As concentrations ranged from 119 to 310 μg/L in drinking water, 46.70-819.20 mg/kg in soil 1.90-6.90 mg/kg in vegetation 1.56-10.79 mg/kg in sheep's wool, and 86.30-656 μg/L in blood samples. These very high As contents, in all parts of the biogeochemical cycle, exceed the recommended normal range for this element compared with a control area. Results indicate that As has moved through all compartments of the biogeochemical cycle by way of direct or indirect pathways. The present investigation illustrated decreased packed cell volume and hemoglobin in sheep from the As-contaminated zone. It was concluded that sheep from the contaminated areas suffer from anemia. Chronic As exposure of the liver was determined by liver function tests. For this purpose, blood aspartate transaminase (AST) and alanine transaminase (ALT) were measured. The results show that serum ALT and AST activities are increased significantly (p < 0.01) in the sheep population exposed to As in the contaminated zone. Moreover, chronic As exposure causes injury to hepatocytes and damages the liver.

Arsenic mobility in sediments from Paracatu River Basin, MG, Brazil

Paracatu River Basin, Minas Gerais, Brazil, houses long areas of irrigated agriculture and gold-, lead-, and zinc-mining activities. This region has a prevalence of sulfide minerals and a natural occurrence of high levels of arsenopyrite. In this work, surface water, groundwater, sediments and local vegetable samples were collected in October 2010 and November 2011 and were analyzed to evaluate arsenic (As) distribution, mobility, and transport in these environmental compartments. All sediment samples (738-2,750 mg kg(-1)) and 37 % of the water samples [less than the limit of detection (LOD) to 110 µg L(-1)] from the rivers and streams of Paracatu had As concentrations greater than the quality standards established by national and international environmental organizations (5.9 mg kg(-1) for sediments and 10 µg L(-1) for water). Most vegetable samples had As concentrations within the normal range for plants (lower than the LOD to 120 mg kg(-1)). A correlation among As concentrations in water, sediment, and vegetable samples was verified.

Groundwater hydrogeochemistry of Trikala municipality, central Greece

Sixty-four samples from the groundwater resources of Trikala municipality, central Greece, were collected during two periods (2006 and 2007) and analyzed for physico-chemical parameters (temperature, pH, specific electrical conductivity, and total dissolved solids), major ions (Ca(2+), Cl(-), HCO(3)(-), K(+), Mg(2+), Na(+), NO(3)(-), SO(4)(2-)), and several potentially toxic elements (Al, B, Ba, Br, Ca, Ce, Cl, Cr, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Nd, Ni, P, Pb, Rb, S, Sc, Si, Sn, Sr, U, V, Y, Zn). European Council directives and USEPA guidelines were used to assess the water quality. The results indicate that all samples are fresh water, suitable for human consumption. All basic ions and physico-chemical parameters have average concentrations below their recommended optimum limits with the exception of electrical conductivity, for January 2007, and nitrate for October 2006 and January 2007 sampling periods. This exceedance is the result of dissolution of minerals such as calcite and dolomite that are present in the surrounding rocks and the application of fertilizers, respectively. Lead is the only element with an average value that exceeds the recommended EC guideline, while special attention should be paid to one borehole (T9) which has elevated NO(3)(-) values which may pose a risk to human health.

One-step synthesis of mesoporous two-line ferrihydrite for effective elimination of arsenic contaminants from natural water

Mesoporous two-line (2-lines) ferrihydrite is successfully synthesized by a facile one-step method. The ferrihydrite is characterized by X-ray diffraction (XRD), Raman spectrum, N(2) adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The 2-lines ferrihydrite with mesoporous structure possesses excellent adsorption performance for arsenic (As(III)) contamination. Experimental results show that As(III) contamination can be effectively removed within 2 h by this 2-lines ferrihydrite, which is attributed to the special mesoporous structure and large surface area (133 m(2) g(-1)). The As(III) loading capacity of our obtained mesoporous 2-lines ferrihydrite is up to 128 mg(As) g(-1)(Fe). In addition, As(III) can be easily desorbed from 2-lines ferrihydrite by simple heat treatment in alkali solution. After reusage for 10 times, it still presents good adsorption performance, indicating the excellent stability of the 2-lines ferrihydrite. Furthermore, the mesoporous 2-lines ferrihydrite is also effective for As(III) removal when some natural water constituents are present. Therefore, the high adsorption capability of the mesoporous 2-lines ferrihydrite makes it a potentially attractive adsorbent for the removal of As(III) contamination from natural water.

Arsenic in the hair of the individuals in Santana-AP-Brazil: significance of residence location

The concentration of arsenic in the hair of the individuals living in Santana city was measured. 121 donors in urban and the periphery area were studied. The periphery of the city shows the highest levels of arsenic (5.94 +/- 6.54 mg kg(-1) - mean; 0.27-23.85 mg kg(-1)). 47.83% in the urban area showed arsenic concentrations of less than 1.00 mg kg(-1), while in the periphery only 11.22% had results below this value. The results showing the influence of residence location. The Principal Component Analysis showed that the variable residence location were responsible for the correct formation of the periphery group.

Changes in hair arsenic concentration in a population exposed to heavy pollution: follow-up investigation in Chenzhou City, Hunan Province, southern China

Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern China in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decreased from 2.95 mg/kg in 2002 to 1.78 mg/kg in 2006, when the percentage of the population with levels over 1 mg/kg only decreased from 93.4% in 2002 to 80.5% in 2006. Over this four-year period, the population with high arsenic concentrations decreased significantly while there was no obvious change in hair arsenic concentration for people who had relatively low concentrations. In terms of age distribution, young and old people had higher hair arsenic concentrations than the middle-aged. All of these results showed that it is difficult to reverse the negative impact of arsenic pollution on human health. Arsenic pollution has a long-term continuous influence on the health of local residents.

Spectrophotometric determination of arsenic in soil samples using 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol (Br-PADAP)

In this paper, a new, simple and sensitive method for arsenic determination in soil is proposed. This is based on the reduction of silver (I) and iron (III) ions by arsine followed by a complexation reaction of iron (II) with the spectrophotometric reagent Br-PADAP 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol. Arsenic determination with a Sandell's sensitivity of 3.1 10-4 cm-2, linear range from 0.1 µg ml-1 to 2.0 µg ml-1 (r560 = 0.9995), molar absorptivity of 2.45 10(5) l mol-1 cm-1 and a concentration detection limit of 1.4 ng ml-1 (3s) were obtained using a 10 ml sample volume. Selectivity was increased with the use of EDTA as a masking agent. The proposed method was applied for arsenic determination in the presence of several ions amounts in digested soil samples. The results revealed that antimony (III), mercury (II), germanium (IV), platinum (IV) interferes at all analyzed proportions. The interferences can be easily removed by the use of EDTA. Precision and accuracy obtained were satisfactory with a R.S.D. < 5 %. Recovery of arsenic in soil samples varied from 95.55 to 102.70 % with a mean of 99.63 %. These results demonstrated that the proposed method is applicable for arsenic analysis in different soil samples.