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A methodological approach is used to characterize arsenic pollution in three soils and to determine arsenic speciation and association with solid phases in three polluted soils. HPLC-ICP-MS was used for arsenic speciation analysis, SEM-EDS and XRD for physical characterization of arsenic pollution, and sequential chemical extractions to identify arsenic distribution. Arsenic was concentrated in the finest size fractions also enriched in iron and aluminium. Total arsenic concentrations in soils are close to 1%. Arsenic was mainly present as arsenate, representing more than 90% of total arsenic. No crystallised arsenic minerals were detected by XRD analysis. SEM-EDS observations indicated arsenic/iron associations. Modified Tessier's procedure showed that arsenic was mainly extracted from amorphous iron oxide phase. The results of this methodological approach lead to predict the formation of iron arsenates in the case of one of the studied soils while arsenic sorption on iron amorphous (hydr)oxides seemed to be the determinant in the two other soils.
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PMID:A methodological approach for the identification of arsenic bearing phases in polluted soils. 1286 Jan 2

ICP-MS analysis recorded historical change (c. 1846 to 2002) in the arsenic concentration of bark included within the trunks (tree bark pockets) of two Japanese oak trees (Quercus crispula), collected at an elevated location approximately 10 km from the Ashio copper mine and smelter, Japan. The arsenic concentration of the bark pockets was 0.016 +/- 0.003 microg cm(-2) c. 1846 (n = 5) and rose 50-fold from c. 1875 to c. 1925, from approximately 0.01 to 0.5 microg cm(-2). The rise coincided with increased copper production in Ashio from local sulfide ores, from 46 tons per year in 1877 to 16,500 tons per year in 1929. Following a decline in arsenic concentration and copper production, in particular during the Second World War, a second peak was observed c. 1970, corresponding to high levels of production from both local (6,000 tons per year) and imported (30,000 tons per year) ores, smelted from 1954. Compared to the local ores, the contribution of arsenic from imported ores appeared relatively low. Arsenic concentrations declined from c. 1970 to the present following the closure of the mine in 1974 and smelter in 1989, recording 0.058 +/- 0.040 microg cm(-2) arsenic (n = 5) in surface bark collected in 2002. The coincident trends in arsenic concentration and copper production indicated that the bark pockets provided an effective record of historical change in atmospheric arsenic deposition.
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PMID:Environmental monitoring of historical change in arsenic deposition with tree bark pockets. 1294 47

Arsenic is an environmental toxicant and a human carcinogen. The kidney, a known target organ of arsenic toxicity, is critical for both in vivo arsenic biotransformation and elimination. This study investigates the potential of an immortalized human proximal tubular epithelial cell line, HK-2, to serve as a representative model for low level exposures of the human kidney to arsenic. Subcytotoxic concentrations of arsenite (< or = 10 micromol/L) and arsenate (< 100 micromol/L) were determined by leakage of LDH from cells exposed for 24 h. Threshold concentrations of arsenite (between 1 and 10 micromol/L) and arsenate (between 10 and 25 micromol/L) were found to affect MTT processing by mitochondria. Biotransformation of subcytotoxic arsenite or arsenate was determined using HPLC-ICP-MS to detect metabolites in cell culture media and cell lysates. Following 24 h, analysis of media revealed that arsenite was minimally oxidized to arsenate and arsenate was reduced to arsenite. Only arsenite was detected in cell lysates. Pentavalent methylated arsenicals were not detected in media or lysates following exposure to either inorganic arsenical. The activities of key arsenic biotransformation enzymes--MMAV reductase and AsIII methyltransferase--were evaluated to determine whether HK-2 cells could reduce and methylate arsenicals. When compared to the activities of these enzymes in other animal tissues, the specific activities of HK-2 cells were indicative of a robust capacity to metabolize arsenic. It appears this human renal cell line is capable of biotransforming inorganic arsenic compounds, primarily reducing arsenate to arsenite. In addition, even at low concentrations, the mitochondria are a primary target for toxicity.
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PMID:Toxicity and metabolism of subcytotoxic inorganic arsenic in human renal proximal tubule epithelial cells (HK-2). 1468 17

An analytical procedure for total arsenic and arsenic species quantification in marine organisms has been developed. Fresh materials are freeze-dried and reduced to powders before analysis. Arsenic is determined either by energy dispersive X-ray fluorescence (EDXRF) directly or by inductively coupled plasma optical emission spectrometry (ICP/OES) after microwave digestion. Arsenic speciation is performed on the extracted sample using liquid chromatography coupled to ICP/OES for arsenobetaine and arsenocholine determination and to the hydride generation-quartz furnace atomic absorption spectrometric technique for arsenite, arsenate, monomethylarsonic and dimethylarsinic acids quantification. Special precautions are taken to avoid losses or contaminations as well as to prevent analytical errors during the quantification stage. Other methods are applied and the corresponding results compared for each step of the procedure. The method is finally validated by means of intercomparison studies within the Measurements and Testing Programme of the European Community (formely BCR).
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PMID:Arsenic speciation in marine organisms: from the analytical methodology to the constitution of reference materials. 1506 44

Health risk associated with dietary arsenic intake may be different for infants and adults. Seafood is the main contributor to arsenic intake for adults while terrestrial-based food is the primary source for infants. Processed infant food products such as rice-based cereals, mixed rice/formula cereals, milk-based infant formula, applesauce and puree of peaches, pears, carrots, sweet potatoes, green beans, and squash were evaluated for total and speciated arsenic content. Arsenic concentrations found in rice-based cereals (63-320 ng/g dry weight) were similar to those reported for raw rice. Results for the analysis of powdered infant formula by inductively coupled plasma-mass spectrometry (ICP-MS) indicated a narrow and low arsenic concentration range (12 to 17 ng/g). Arsenic content in puree infant food products, including rice cereals, fruits, and vegetables, varies from <1 to 24 ng/g wet weight. Sample treatment with trifluoroacetic acid at 100 degrees C were an efficient and mild method for extraction of arsenic species present in different food matrixes as compared to alternative methods that included sonication and accelerated solvent extraction. Extraction recoveries from 94 to 128% were obtained when the summation of species was compared to total arsenic. The ion chromatography (IC)-ICP-MS method selected for arsenic speciation allowed for the quantitative determination of inorganic arsenic [As(III) + As(V)], dimethylarsinic acid (DMA), and methylarsonic acid (MMA). Inorganic arsenic and DMA are the main species found in rice-based and mixed rice/formula cereals, although traces of MMA were also detected. Inorganic arsenic was present in freeze-dried sweet potatoes, carrots, green beans, and peaches. MMA and DMA were not detected in these samples. Arsenic species in squash, pears, and applesauce were not detected above the method detection limit [5 ng/g dry weight for As(III), MMA, and DMA and 10 ng/g dry weight for As(V)].
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PMID:Total arsenic determination and speciation in infant food products by ion chromatography-inductively coupled plasma-mass spectrometry. 1508 7

Speciation of arsenicals in biological samples is an essential tool to gain insight into its distribution in tissues and its species-specific toxicity to target organs. Biological samples (urine, hair, fingernail) examined in the present study were collected from 41 people of West Bengal, India, who were drinking arsenic (As)-contaminated water, whereas 25 blood and urine samples were collected from a population who stopped drinking As contaminated water 2 years before the blood collection. Speciation of arsenicals in urine, water-methanol extract of freeze-dried red blood cells (RBCs), trichloroacetic acid treated plasma, and water extract of hair and fingernail was carried out by high-performance liquid chromatography (HPLC)-inductively coupled argon plasma mass spectrometry (ICP MS). Urine contained arsenobetaine (AsB, 1.0%), arsenite (iAs(III), 11.3), arsenate (iAs(V), 10.1), monomethylarsonous acid (MMA(III), 6.6), monomethylarsonic acid (MMA(V), 10.5), dimethylarsinous acid (DMA(III), 13.0), and dimethylarsinic acid (DMA(V), 47.5); fingernail contained iAs(III) (62.4%), iAs(V) (20.2), MMA(V) (5.7), DMA(III) (8.9), and DMA(V) (2.8); hair contained iAs(III) (58.9%), iAs(V) (34.8), MMA(V) (2.9), and DMA(V) (3.4); RBCs contained AsB (22.5%) and DMA(V) (77.5); and blood plasma contained AsB (16.7%), iAs(III) (21.1), MMA(V) (27.1), and DMA(V) (35.1). MMA(III), DMA(III), and iAs(V) were not found in any plasma and RBCs samples, but urine contained all of them. Arsenic in urine, fingernails, and hair are positively correlated with water As, suggesting that any of these measurements could be considered as a biomarker to As exposure. Status of urine and exogenous contamination of hair urgently need speciation of As in these samples, but speciation of As in nail is related to its total As (tAs) concentration. Therefore, total As concentrations of nails could be considered as biomarker to As exposure in the endemic areas.
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PMID:Speciation of arsenic in biological samples. 1527 10

The objective of this study was to determine arsenic exposure via drinking water and to characterize urinary arsenic excretion among adults in the Yaqui Valley, Sonora, Mexico. A cross-sectional study was conducted from July 2001 to May 2002. Study subjects were from the Yaqui Valley, Sonora, Mexico, residents of four towns with different arsenic concentrations in their drinking water. Arsenic exposure was estimated through water intake over 24 h. Arsenic excretion was assessed in the first morning void urine. Total arsenic concentrations and their species arsenate (As V), arsenite (As III), monomethyl arsenic (MMA), and dimethyl arsenic (DMA) were determined by HPLC/ICP-MS. The town of Esperanza with the highest arsenic concentration in water had the highest daily mean intake of arsenic through drinking water, the mean value was 65.5 microg/day. Positive correlation between total arsenic intake by drinking water/day and the total arsenic concentration in urine (r = 0.50, P < 0.001) was found. Arsenic excreted in urine ranged from 18.9 to 93.8 microg/L. The people from Esperanza had the highest geometric mean value of arsenic in urine, 65.1 microg/L, and it was statistically significantly different from those of the other towns (P < 0.005). DMA was the major arsenic species in urine (47.7-67.1%), followed by inorganic arsenic (16.4-25.4%), and MMA (7.5-15%). In comparison with other reports the DMA and MMA distribution was low, 47.7-55.6% and 7.5-9.7%, respectively, in the urine from the Yaqui Valley population (except the town of Cocorit). The difference in the proportion of urinary arsenic metabolites in those towns may be due to genetic polymorphisms in the As methylating enzymes of these populations.
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PMID:Arsenic drinking water exposure and urinary excretion among adults in the Yaqui Valley, Sonora, Mexico. 1532 72

Concentrations of Ti, Ga, As, Sc, Zr, Sn, Hf, Th, U and Y have been determined for 70 paddy soils from 14 villages, selected throughout Sri Lanka by means of ICP-MS. The mean elemental contents of all paddy soil samples were 6120 Ti, 14.1 Ga, 0.84 As, 7.26 Sc, 129 Zr, 2.27 Sn, 3.64 Hf, 12.71 Th, 1.53 U, and 13.35 Y (all data in microg/g). Paddy soils were classified into groups based on morphology and climate. Higher contents of Th and U were found in the wet zone lowland soils whereas the higher Ti contents were observed in dry zone soils. Arsenic, Zr and Hf contents were comparatively similar in all regions. Factor analysis was used to identify the relationships between the contents of elements.
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PMID:The abundances of rarer trace elements in paddy (rice) soils of Sri Lanka. 1568 60

Asian clam Corbicula fluminea, the amphipod Dikerogammarus villosus and the macrophyte Nuphar lutea were tested for investigating spatial and temporal variability in the bioavailability of tin and arsenic in the River Lippe, Germany. Samples were collected from September 2002 to May 2003 at a tin polluted site (source pollution) and a reference site. Additional screening sampling was carried out twice in April 2003 to test the extent of As and Sn concentration in periphyton (aufwuchs) samples. Accumulated Sn and As concentrations were measured with ICP-MS after sample processing (dissection, cryo-milling) and digestion. Quality control was performed by parallel analysis of three certified reference materials. Measurable As and Sn contents in plant tissues were only detectable in roots (below 30 microg kg(-1) and 20 microg kg(-1) for As and Sn, respectively). Homogenates from C. fluminea and D. villosus tissues showed site-dependent trace metal contents. Elevated bioavailability of Sn is present downstream of the sewage discharge of the world's biggest producer of tributyltin (TBT) at Luenen (northern Ruhr region). In comparison to C. fluminea, D. villosus shows higher concentrations of tin in samples from both sites. Arsenic concentrations in C. fluminea remain constant with increasing shell size, whereas tin shows a size-dependent accumulation. The results indicate that Corbicula fluminea and Dikerogammarus villosus are suitable passive biomonitoring organisms for Sn, but As levels might be actively regulated. The concentration of tin in the periphyton (aufwuchs) samples was found to be much higher in samples from a contaminated site (428 +/- 63 vs. 1949 +/- 226 microg kg(-1)).
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PMID:Biomonitoring of tin and arsenic in different compartments of a limnic ecosystem with emphasis on Corbicula fluminea and Dikerogammarus villosus. 1573 79

Inorganic arsenicals such as arsenite (iAs(III)) and arsenate (iAs(V)) are well-known human carcinogens. Arsenic is metabolized by repetitive reduction and oxidative methylation, and is excreted mainly in urine as monomethylated arsenicals (MMAs) and dimethylated arsenicals (DMAs). Recently, it has been shown that iAs(III) administered intravenously or orally is excreted into bile as arsenic-glutathione (As-GSH) complexes such as arsenic triglutathione [As(GS)(3)] and methylarsenic diglutathione [CH(3)As(GS)(2)]. In order to carry out the speciation of As-GSH complexes, it is important to understand their stability. The present study was designed to clarify the stability of As-GSH complexes in rat bile, and the role of GSH in stabilizing these complexes. Arsenic species were separated on an anion-exchange column and were analyzed by high-performance liquid chromatography-inductively coupled argon plasma mass spectrometry (HPLC-ICP MS). As(GS)(3) and CH(3)As(GS)(2) were unstable in bile and were hydrolyzed to iAs(III) and monomethylarsonous acid (MMA(III)) in the absence of GSH. As(GS)(3) appeared to be stable in the presence of 10mM GSH. Exogenously added GSH also stabilized CH(3)As(GS)(2) in bile at the concentrations of 5mM or higher. It has been suggested that trivalent arsenicals, especially MMA(III), are more toxic than corresponding pentavalent ones. These results suggest that GSH plays an important role in preventing hydrolysis of As-GSH complexes and the generation of well-known toxic trivalent arsenicals.
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PMID:Stability of arsenic metabolites, arsenic triglutathione [As(GS)3] and methylarsenic diglutathione [CH3As(GS)2], in rat bile. 1586 54


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