Changing Concept of Arsenic Toxicity with Development of Speciation Techniques
01 Jan 2015-pp 179-201
TL;DR: In this paper, the toxicity of arsenite (AsO 3 3 − ) was found to be more toxic than arsenate (O 4 5 − ) and trivalent dimethylated arsenicals (AsH 3 ).
Abstract: Arsenic (As), being a metalloid, is well known for its versatile applications to mankind. Arsenic is coined by USEPA as the number one carcinogen. The human body can metabolize arsenic into different forms after intake via water, soils, and food as well as by inhalation. Due to lack of instrumental techniques the total concentration of As was initially considered as the indicator of toxicity. Subsequently, arsenite ( AsO 3 3 − ) was found to be more toxic than arsenate ( AsO 4 5 − ). After the development of hyphenated techniques, the existence of methylated As compounds were reported and methylation was considered the detoxification process in humans. Toxicological studies reported that mono- and dimethylated pentavalent As compounds were less toxic than arsenite (As III ). During the last decade significant developments in speciation techniques have taken place, which has altered the traditional concept of the toxicity of methylated As compounds. After the identification of trimethylated arsenicals, the methylation of As compounds was considered to be the toxication step in humans. Trivalent dimethylated arsenicals were found to be more toxic than arsine (AsH 3 ). Additional research is on going to elucidate the fate of thioarsenicals regarding toxicity in humans.
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TL;DR: In this article, the fate of Sb and As downstream of the abandoned Su Suergiu mine (Sardinia, Italy) and surrounding areas was investigated, and water samples were neutral to slightly alkaline.
Abstract: We investigated the fate of Sb and As downstream of the abandoned Su Suergiu mine (Sardinia, Italy) and surrounding areas. The mined area is a priority in the Sardinian remediation plan for contaminated sites due to the high concentrations of Sb and As in the mining-related wastes, which may impact the Flumendosa River that supplies water for agriculture and domestic uses. Hydrogeochemical surveys conducted from 2005 to 2015 produced time-series data and downstream profiles of water chemistry at 46 sites. Water was sampled at: springs and streams unaffected by mining; adits and streams in the mine area; drainage from the slag heaps; stream water downstream of the slag drainages; and the Flumendosa River downstream from the confluence of the contaminated waters. At specific sites, water sampling was repeated under different flow conditions, resulting in a total of 99 samples. The water samples were neutral to slightly alkaline. Elevated Sb (up to 30 mg L−1) and As (up to 16 mg L−1) concentrations were observed in water flowing from the slag materials from where the Sb ore was processed. These slag materials were the main Sb and As source at Su Suergiu. A strong base, Na-carbonate, from the foundry wastes, had a major influence on mobilizing Sb and As. Downstream contamination can be explained by considering that: (1) the predominant aqueous species, Sb(OH)6
− and HAsO4
−2, are not favored in sorption processes at the observed pH conditions; (2) precipitation of Sb- and As-bearing solid phases was not observed, which is consistent with modeling results indicating undersaturation; and (3) the main decrease in dissolved Sb and As concentrations was by dilution. Dissolved As concentrations in the Flumendosa River did not generally exceed the EU limit of 10 µg L−1, whereas dissolved Sb in the river downstream of the contamination source always exceeded the EU limit of 5 µg L−1. Recent actions aimed at retaining runoff from the slag heaps are apparently not sufficiently mitigating contamination in the Flumendosa River.
25 citations
Cites background from "Changing Concept of Arsenic Toxicit..."
...…Cagliari University, via Trentino 51, 09127 Cagliari, Italy 2 US Geological Survey, 3215 Marine St., Boulder, CO 80303, USA 1 3 As(III)-bearing species [As(OH)0 3 ] or dissolved As(V)bearing species [AsO(OH)0 3 ] and dissociated species], with As(V) being considered less toxic (Mandal 2015)....
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TL;DR: In this paper, a co-precipitation method of Fe(III) and Fe(II) in alkaline media was applied to obtain Fe3O4 NPs.
Abstract: The contamination of drinking water with arsenic has been a problem in a lot of countries around the world because of its toxicological and carcinogenic effects on human health. Porous materials modified with Fe3O4 nanoparticles (Fe3O4 NPs) represent convenient removers for that contaminant. A co-precipitation method of Fe(III) and Fe(II) in alkaline media was applied to obtain Fe3O4 NPs. In a first stage, single nanoparticles were synthesized and stabilized with carboxylic acids. A characterization with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and X-ray diffraction (XRD) confirms a magnetite-type structure. Moreover, transmission electron microscopy (TEM) and calculations from XRD data using Scherrer’s equation indicate an average particle size of 13 nm and an average crystallite size of 10 nm, both independent of the stabilizer used. Then, the co-precipitation method studied was applied to modify kaolin, bentonite, diatomite, and silica and thus prepare magnetic composites having support-magnetite weight ratios of 2:1. Among them, silica-modified material presented the best hydraulic characteristics, an important aspect for large-scale applications such as removal under gravity. This composite has the capacity to remove up to 80 and 70% for initial concentrations of 25 and 50 μg/L, respectively, representing a convenient remover for processes developed in subsequent stages or in continuous flow.
19 citations
Cites background from "Changing Concept of Arsenic Toxicit..."
...Moreover, toxicological studies reported that mono- and dimethylated pentavalent As compounds were less toxic than arsenite [As(III)] (Mandal 2014)....
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TL;DR: In this paper, an integrated green process for the continuous oxidation and biomineralization of the most toxic As(III) from acidic streams using a laboratory-scale air-lift bioreactor operated at thermoacidophilic conditions and fed with Fe(II) as electron donor was reported.
12 citations
TL;DR: In this paper , a facile hydrothermal strategy was used to prepare praseodymium vanadate nanoparticles for real-time detection of arsenic drug roxarsone (RXS).
Abstract: Nanomaterials have versatile properties owing to their high surface-to-volume ratio and can thus be used in a variety of applications. This work focused on applying a facile hydrothermal strategy to prepare praseodymium vanadate nanoparticles due to the importance of nanoparticles in today's society and the fact that their synthesis might be a challenging endeavor. The structural and morphological characterizations were carried out to confirm the influence of the optimizations on the reaction's outcomes, which revealed praseodymium vanadate (PrVO4) with a tetragonal crystal system. In this regard, the proposed development of electrochemical sensors based on the PrVO4 nanocatalyst for the real-time detection of arsenic drug roxarsone (RXS) is a primary concern. The detection was measured by amperometric (i-t) signals where PrVO4/SPCE, as a new electrochemical sensing medium for RXS detection, increased the sensitivity of the sensor to about ∼2.5 folds compared to the previously reported ones. In the concentration range of 0.001-551.78 μM, the suggested PrVO4/SPCE sensor has a high sensitivity for RXS, with a detection limit of 0.4 nM. Furthermore, the impact of several selected potential interferences, operational stability (2000 s), and reproducibility measurements have no discernible effect on RXS sensing, making it the ideal sensing device feasible for technical analysis. The real-time analysis reveals the excellent efficiency and reliability of the prosed sensor toward RXS detection with favorable recovery ranges between ±97.00-99.66% for chicken, egg, water, and urine samples.
9 citations
TL;DR: In this paper , a facile hydrothermal synthesis route of rare earth vanadates TVO4 (T = Ho, Y, Dy) was presented as an efficient electrocatalyst for the simultaneous detection of nitrofurazone (NF) and roxarsone (RX).
9 citations
References
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Book•
01 Jan 1992
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!
78,324 citations
TL;DR: This review deals with environmental origin, occurrence, episodes, and impact on human health of arsenic, a metalloid occurs naturally, being the 20th most abundant element in the earth's crust.
3,166 citations
2,475 citations
TL;DR: It is suggested that trivalent methylated arsenicals, intermediary products of arsenic methylation, may significantly contribute to the adverse effects associated with exposure to iAs, and high methylation capacity does not protect cells from the acute toxicity of triavalent arsenicals.
Abstract: Biomethylation is considered a major detoxification pathway for inorganic arsenicals (iAs). According to the postulated metabolic scheme, the methylation of iAs yields methylated metabolites in which arsenic is present in both pentavalent and trivalent forms. Pentavalent mono- and dimethylated arsenicals are less acutely toxic than iAs. However, little is known about the toxicity of trivalent methylated species. In the work reported here the toxicities of iAs and trivalent and pentavalent methylated arsenicals were examined in cultured human cells derived from tissues that are considered a major site for iAs methylation (liver) or targets for carcinogenic effects associated with exposure to iAs (skin, urinary bladder, and lung). To characterize the role of methylation in the protection against toxicity of arsenicals, the capacities of cells to produce methylated metabolites were also examined. In addition to human cells, primary rat hepatocytes were used as methylating controls. Among the arsenicals examined, trivalent monomethylated species were the most cytotoxic in all cell types. Trivalent dimethylated arsenicals were at least as cytotoxic as trivalent iAs (arsenite) for most cell types. Pentavalent arsenicals were significantly less cytotoxic than their trivalent analogs. Among the cell types examined, primary rat hepatocytes exhibited the greatest methylation capacity for iAs followed by primary human hepatocytes, epidermal keratinocytes, and bronchial epithelial cells. Cells derived from human bladder did not methylate iAs. There was no apparent correlation between susceptibility of cells to arsenic toxicity and their capacity to methylate iAs. These results suggest that (1) trivalent methylated arsenicals, intermediary products of arsenic methylation, may significantly contribute to the adverse effects associated with exposure to iAs, and (2) high methylation capacity does not protect cells from the acute toxicity of trivalent arsenicals.
934 citations
TL;DR: Data demonstrate that MMA(III), an intermediate in in organic arsenic methylation, is highly toxic and again raises the question as to whether methylation of inorganic arsenic is a detoxication process.
674 citations