Narrow Results

The World Health Organization has labeled the problem of arsenic contamination of groundwater in South Asia as “the largest mass poisoning in human history.” Various technical solutions to the problem fall into one of two broad categories: (i) cleaning contaminated water before human consumption and (ii) encouraging people to switch to less contaminated water sources. In this paper, we review research on the behavioral, social, political, and economic factors that determine the field-level effectiveness of the suite of technical solutions and the complexities that arise when scaling such solutions to reach large numbers of people. We highlight the conceptual links between arsenic-mitigation policy interventions and other development projects in Bangladesh and elsewhere, as analyzed by development economists, that can shed light on the key social and behavioral mechanisms at play. We conclude by identifying the most promising policy interventions to counter the arsenic crisis in Bangladesh. We support a national well-testing program combined with interventions that address the key market failures (affordability, coordination failures, and elite and political capture of public funds) that currently prevent more deep-well construction in Bangladesh.

Traditional Chinese Medicine (TCM) is a practical medicine based on thousands of years of medical practice in China. Arsenic dispensing powder (ADP) has been used as a treatment for MDS patients with a superior efficacy on anemia at Xiyuan Hospital of China Academy of Chinese Medical Sciences. In this study, we retrospectively analyzed MDS patients that received ADP treatment in the past 9 years and confirmed that ADP improves patients’ anemia and prolongs overall survival in intermediate-risk MDS patients. Then, we used the MDS transgenic mice model and cell line to explore the drug mechanism. In normal and MDS cells, ADP does not show cellular toxicity but promotes differentiation. In mouse MDS models, we observed that ADP showed significant efficacy on promoting erythropoiesis. In the BFU-E and CFU-E assays, ADP could promote erythropoiesis not only in normal clones but also in MDS clones. Mechanistically, we found that ADP could downregulate HIF1A in MDS clones through upregulation of VHL, P53 and MDM2, which is involved in two parallel pathways to downregulate HIF1A. We also confirmed that ADP upregulates GATA factors in normal clones. Thus, our clinical and experimental studies indicate that ADP is a promising drug to promote erythropoiesis in both MDS and normal clones with a superior outcome than current regular therapies. ADP promotes erythropoiesis in myelodysplastic syndromes via downregulation of HIF1A and upregulation of GATA factors.

Recent advances in the chemistry of main group porphyrin complexes are surveyed. New, unprecedented structural types for porphyrin complexes which have been revealed from the recent reports of boron and tellurium porphyrins are described. Advances in the preparation and reactivity of Group 14 (silicon and tin) and Group 15 porphyrin complexes are discussed. A systematic variation in the out-of-plane distortion (ruffling) of light element Group 14 and 15 porphyrin complexes has become apparent now that a significant number of structurally characterized examples are at hand.

Adsorption is widely applied to remove arsenic from water. This paper reviewed and compared the recent progresses on the arsenic removal by adsorption using two-dimensional and three-dimensional graphene-based materials as adsorbents. Functional graphene sheet achieved the largest As(III) adsorption capacity of 138.79mg/g, while Mg-Al LDH/GO2 showed the largest As(V) adsorption capacity of 183.11mg/g. Parameters including pH, temperature, co-existing ions and loaded metal or metal oxide affected the adsorption process. The adsorption mechanisms of graphene-based materials for As(III) and As(V) could be explained by surface complexation and the electrostatic attraction, respectively. Future works are suggested to focus on regenerating of two-dimensional graphene-based adsorbents and developing the three-dimensional with large specific surface area and better adsorption performance.

Pytoremediation using an arsenic hyperaccumulator, Petris vittata L., has generated an increasing interest worldwide due to both environmentally sound and cost effectiveness. However the mechanism of arsenic accumulation by this fern is not clear at this time. This study examined the uptake of arsenate (As(V)) and arsenite (As(III)) by a hydroponic culture of Pteris vittata using both in-air submilli-PIXE for different parts of the fern and in-air micro-PIXE for the tissue cells. These PIXE analysis systems used 3 MeV proton beams from a 4.5-MV single-ended Dynamitron accelerator at Tohoku University, Japan. The fern took up both arsenate and arsenite from hydroponic solutions which were spiked with 50 mg of arsenic per litter. Final amount of arsenic accumulation in the fern is 1,500 mg per kg (wet weight) of the plant biomass in arsenite treatment and 1,100 mg per kg in arsenate treatment. Arsenic accumulation was not observed at the root parts of the ferns. The in-vivo mapping of elements by submilli-PIXE analyses on the fern laminas showed the arsenic accumulation in the edges of a pinna. The micro-PIXE analyses revealed arsenic maps homogeneously distributed in cells of the lamina, stem and rhizome of the fern. These results indicate that arsenic, both arsenate and arsenite in a contaminated medium are translocated quickly from roots to fronds of Pteris vittata, and distributes homogeneously into tissue cells of the fern laminas.

Pteris vittata is a fern reported to be an arsenic hyper-accumulator. To develop the practical application of the fern to a phytoremediation technique, it is necessary to explicate the effective accumulation mechanism. In this study, the arsenic distribution and the elemental correlation in the cellular level were examined in the fronds supplied with arsenate and arsenite separately via xylem vessel using an in-air micro-PIXE system at Tohoku University. The difference in transportation rate between arsenate and arsenite as well as the translocation of elements necessary for plant metabolism was revealed in different tissues of the fronds accumulating arsenic in high concentration. Hence, the in-air micro-PIXE analysis is an effective measure for undertaking phytoremediation research of hyper-accumulator plants.

The samples of common salts available in Japan and Mongolia were analyzed for the presence of heavy elements by PIXE spectrometry using 2.5 MeV proton beam at the Tokyo Institute of Technology Van de Graaff Laboratory. The samples were dissolved in water and insoluble and soluble fractions were determined separately. The soluble constituents were treated with pre-concentration method by using DBDTC to form the complexes appropriate to percolation through a Nuclepore Track - etch Membrane. Insoluble particles were precipitated on the filter surface for subsequent direct irradiation. Combined As and Pb concentrations in insoluble portion of salts were found in the range of 7.2 – 102 ppm based on mass analysis of insoluble materials collected on Nuclepore Track - etch Membrane of the pore diameter 0.4μm. This level of toxic heavy metals makes a caution from the view-point of their safe intake.

Arsenic concentration in 13 well waters, 9 pond waters, 10 agricultural waters and a coconut juice taken in Comilla district, Bangladesh, where the problem of arsenic pollution is the most severe, was investigated. High-level arsenic is detected even in the well water which has been kept drinking by the people. Relatively high arsenic concentration was detected for some pond and farm waters even though the sampling was performed just after the rainy season and the waters were expected to be highly diluted. Clear relationship was observed in elemental compositions between the pond water and the coconut juice collected at the edge of the water. These results are expected to become the basic information for evaluating the risk of individual food such as cultured fishes, shrimps and farm products, and for controlling total intakes of arsenic. In order to solve the problem of transportation of water samples internationally, a simple method of target preparation performed at the sampling cite was established and its validity was confirmed. All targets were prepared at the sampling cites in this study on the basis of this method.

We have analyzed the hair of inhabitant of a district in Mongolia where the arsenic contamination is doubted. The study area includes a village where the authors noticed possible arsenic contamination in 2004 (S. Murao, B. Tumenbayar, K. Sera, S. Futatsugawa and T. Waza, Finding of high level arsenic for Mongolian villagers' hair, Int. J. PIXE 14 (2004) 125–131). The investigation team visited each family, explained the purpose of visit, obtained their consent, and cut the untreated virgin hairs. The result reaffirmed high arsenic concentration, up to 11ppm, for most of the subjects. Since the arsenic anomaly in the study area is observed regardless the occupation, it is highly probable that the area is contaminated on a regional scale.

Ultrafine nanoparticles owing to their increased surface to volume ratio, coupled with the ability to tune their surface properties through molecular modification have made them ideal for their detection and remediation of broad range of environmental contaminants. Arsenic contamination has become a worldwide epidemic and remediation of this problem needs the development of technology with improved materials and systems with high efficiency. In the present study, we have demonstrated a simple and efficient method using surface functionalized ultrafine iron oxide nanoparticles for absolute removal of arsenic from arsenic treated water with low contact time period and low adsorbent dose. The efficiency of arsenic removal has been drastically improved by considering nanoparticles of size 10 nm and subsequent surface engineering of the nanoparticles resulting more adsorption sites being exposed to arsenic. The mechanism for adsorption was identified through electron microscopic and spectroscopic studies. The adsorption equilibrium data were well fitted to Freundlich isotherm.

An analysis of the equations used for modeling thermal arsenic diffusion in silicon has been carried out. It was shown that for arsenic diffusion governed by the vacancy-impurity pairs and the pairs formed due to interaction of impurity atoms with silicon self-interstitials in a neutral charge state, the doping process can be described by the Fick’s second law equation with a single effective diffusion coefficient which takes into account two impurity flows arising due to interaction of arsenic atoms with vacancies and silicon self-interstitials, respectively. Arsenic concentration profiles calculated with the use of the effective diffusivity agree well with experimental data if the maximal impurity concentration is near the intrinsic carrier concentration. On the other hand, for higher impurity concentrations a certain deviation in the local regions of arsenic distribution is observed. The difference from the experiment can occur due to the incorrect use of effective diffusivity for the description of two different impurity flows or due to the formation of nonuniform distributions of neutral vacancies and neutral self-interstitials in heavily doped silicon layers. We also suppose that the migration of nonequilibrium arsenic interstitial atoms makes a significant contribution to the formation of a low concentration region on thermal arsenic diffusion.

Man has always used his environment to heal himself. Until 1869 all medicines came mainly from plants (e.g. opium for pain relief, Figure 8.46, Section 8.8.1) or animals (e.g. badger skin and meat to relieve snake or scorpion bites). In 2010, there were 1000 active ingredients in drugs sold in pharmacies, of which 10% were unmodified natural products, 29% were derivatives of natural products (hemisynthesis) and 61% were synthetic products. Using bio-informatics and artificial intelligence methods, an estimated 166 billion different molecules can be prepared by combining 17 atoms comprising C, N, O, S, F, Cl, Br and I, and by applying known synthesis methods and standard stability criteria. By applying medicinal chemistry criteria (structure/biological activity relationships) to this molecular space called GBD17, it is estimated that 10 million of these molecules could become drugs…

The groundwater pollution by arsenic in Bangladesh causes a serious problem for millions of people who are exposed to poisoning by this toxic element. In an attempt to evaluate the extent of arsenic poisoning, hair samples of people living in Pabna district were collected. The hair samples were analyzed using Proton Induced X-ray Emission (PIXE) through exciting the atoms of a specimen so that their intensities can be converted into elemental concentrations in the specimen. The elements present in the specimen are identified by the corresponding X-ray energies and their concentrations are deduced from the X-ray intensities. The results from hair samples indicate substantially higher level of arsenic than those demarcated as toxic levels, in people from member families both affected and non-affected by poisoning. We correlate it with exceedingly high arsenic concentration in drinking water far above the permissible limit. The analytical results are compared with the results of arsenic and other elemental analysis of 160 Bangladeshi hair samples with that of 250 Japanese samples. The results show markedly higher levels of arsenic, manganese, iron and lead where the latter three elements show a positive relation with arsenic in the case of Bangladeshi as compared to the samples from Japan. On the other hand, selenium concentrations show very low level in the Bangladeshi samples compared to Japanese, displaying an inverse relationship with arsenic. The mechanism of arsenic in relation to other elements in the human body needs further investigation. The preliminary results call for detailed experimental and epidemiological studies to further characterize these aspects.

Intake of heavy metals from contaminated agricultural products represents a significant pathway for human exposure. Banglish village in the Comilla district is one of the most devastated arsenic (As) contaminated areas in Bangladesh. This study focus whether As is solely responsible for causing arsenicosis or whether some other heavy metals have a synergistic effect on the toxicity of As. The study sampled various leafy and non-leafy vegetables and groundwaters were analyzed by using the Proton Induced X-ray Emission (PIXE) method. The results revealed that both the vegetables and the groundwater were highly contaminated with As and lead (Pb), although the contents in the vegetables and the groundwater varied depending on species and tube wells. As and Pb concentrations in the edible part of all tested vegetables and in groundwater exceeded the permissible intake levels of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). The findings inferred that the inhabitants of the study area are experiencing health risks resulting from the intake of As and Pb, and that Pb might have a synergistic role with As by aggravating the arsenicosis. The potential health risks due to Pb is being reported for the first time in Bangladesh.

In recent years, the number of artisanal gold miners in Mongolia is drastically increasing. They use mercury to extract gold from ore and release it to the environment and this fact has been an issue of concern in the nation. In order to monitor the degree of exposure to mercury, artisanal miners' hairs from a typical mining site, Boroo, were analyzed by PIXE at Nishina Memorial Cyclotron Center, Japan. The result indicated that mercury content in the hairs is very low in spite of the miners' practice to work in mercury fume for smelting. However the result showed high level of arsenic, up to 3.2 ppm, although miners' do not use arsenic in the smelting process.

This investigation focuses on the arsenic contamination problems in tube well groundwater systems and the different forms of arsenic and other toxic elements accumulated in human hair samples taken in a rural area of Allahabad, Uttar Pradesh, India. The local residents at the study site depend on groundwater as their major source of household water. The oxidation reduction potential (ORP) and pH of groundwater samples were measured directly after the sampling of groundwater. Arsenic concentrations were measured directly in water samples by a colorimetric arsenic analysis kit after the water was pumped from a tube well and/or at a nearby laboratory. Human hair samples from the residents of the villages in the study site were analyzed by PIXE to measure a wide range of elements. An atomic absorption spectrometer was also used to measure arsenic concentrations. The results indicated that the concentrations of arsenic in groundwater and human hair were significantly higher in the village of Bada Kanjasa than in the villages of Kanua and Chota Kanjasa (P< 0.05), clearly indicating that the higher arsenic concentration in groundwater reflected the accumulation of arsenic in human hair in the residents of Bada Kanjasa. The PIXE analysis also revealed an unusually high concentration of lead in human hair samples from Chota Kanjasa. Although the actual health effects and the detailed exposure mechanisms remain to be investigated, lead pollution is suspected to be the source of the exposure.

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The Arsenic in steel commonly comes from a certain amount of iron ore but it is difficult to remove them in the iron and steelmaking process because its oxidation potential is lower than that of Iron. In this study, a certain amount of rare earth metal, Cerium and a metal with low melting point, Arsenic were closed in the barrel-shaped cylinder machine by H08 steel, heated to 1323K for 50 hours. Interaction among the cerium, arsenic and iron in the barrel-shaped cylinder were studied by X-ray diffraction, optical microscopy, and electronic probe microscopy analysis. The result shows that the ternary compound Ce12Fe57.5As41 can be developed at 1323K when the atomic ratio of Cerium to Arsenic is 1:3. The binary compound CeAs is the main product at 1323K in the Fe-As-Ce system. The eutectic compound Fe2As can be precipitated from ferrite with the temperature decreasing.