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Arsenic (As) contamination in wells is common throughout the northeastern United States. It is well documented that lead-arsenate (PbHAsO4 ) pesticides were widely used on fruit tree orchards from the 1890s to 1950s. This study evaluates the potential for As contamination of groundwater from former orchards in Connecticut, where there were over 47,000 orchards in 1935. A proximity analysis involving 189 orchards and 114 domestic wells was conducted to assess the spatial relationship between historic orchards and As in wells. Field studies were then conducted to characterize As and lead (Pb) distributions in soils and wells near historic orchards. The proximity analysis found that the wells with no detected As were further away from historic orchards and had fewer historic orchards within their vicinity when compared with wells that contained As. The field investigations found that elevated levels of As and Pb were widespread in soils from orchards established by 1951, with some As concentrations exceeding 200 ppm. In some soils, As and Pb were leachable at concentrations exceeding USEPA drinking water standards in synthetic precipitation laboratory tests. It was also found that the wells nearest to the impacted soils tended to contain the highest As concentrations, while the wells located in areas that were forested prior to 1970 contained no As. Overall, this study found that As and Pb from legacy pesticide residues are still abundant in former orchard soils and that a strong spatial relationship exists between As-contaminated wells and historic orchards. Greater consideration should be given to historic orchard soils as a potential contributing nonpoint source of As to the groundwater in Connecticut, where domestic well contamination rates are high.

To evaluate the pollution level of toxic elements in edible mushrooms from Jilin Province, China, the lead, cadmium, mercury, and arsenic content present in them were monitored and evaluated. A total of 610 edible mushroom samples, including fresh and dried, were collected from nine cities in the Jilin Province. The concentrations of lead, cadmium, mercury, and arsenic ranged from 0.007 to 3.31, 0.006 to 48.52, 0.003 to 0.56, and 0.008 to 57.34 mg/kg, respectively, in dried samples, and 0.007 to 0.06, 0.006 to 0.17, 0.003 to 0.06, and 0.008 to 0.12 mg/kg, respectively, in fresh samples. The concentration of cadmium and arsenic exceeded the standard (Cd ≤ 0.2 mg/kg, Cd of Lentinus edodes ≤ 0.5 mg/kg, and As ≤ 0.5 mg/kg) in some mushroom samples. The bioconcentration levels of lead, cadmium, mercury, and arsenic depended on the edible mushroom species, environment, and the physicochemical properties of lead, cadmium, mercury, and arsenic. The results of the single factor pollution index, a method used to calculate the level of single elements in substances, showed that all edible mushrooms were at the level of unpolluted except Tricholoma matsutake and Pleurotus eryngii. The comprehensive factor (P) for T. matsutake was 1.093. The comprehensive factor pollution index, a method used to calculate the level of combined mixture in substances, was in the unpolluted level, except for T. matsutake. The pollution index results showed that cadmium and arsenic concentrations were lightly polluting in some mushroom samples. The health risk index for arsenic was the highest. Therefore, more attention should be paid to arsenic contamination in T. matsutake and P. eryngii in the Jilin Province, China. PRACTICAL APPLICATION: In this paper, we evaluated the contamination levels and associated safety issues of four toxic elements, lead, cadmium, mercury, and arsenic, in edible mushrooms. The results showed that cadmium and arsenic concentrations were lightly polluting in some mushroom samples.

Arsenic in private drinking water wells is a significant problem across much of eastern Wisconsin, USA. The release mechanism and stratigraphic distribution of sulfide and iron (hydr)oxide sources of arsenic in bedrock aquifers are well understood for northeastern Wisconsin. However, recent geologic mapping has identified numerous small bedrock folds to the south, and the impact of these geologic structures on local groundwater flow and well contamination has been little studied. This paper examines the hydrologic and structural effects of the Beaver Dam anticline, southeast Wisconsin, on arsenic in groundwater in the region. Multivariate logistic regression shows wells near the Beaver Dam anticline are statistically more likely to detect arsenic in groundwater compared to wells farther away. Structural and hydrologic changes related to folding are interpreted to be the cause. Core drilled near the fold axis is heavily fractured, and many fractures are filled with sulfides. Elevated hydraulic conductivity estimates are also recorded near the fold axis, which may reflect a higher concentration of vertical fractures. These structural and hydrologic changes may have led to systematic changes in the distribution and concentration of arsenic-bearing mineral hosts, resulting in the observed detection pattern. For areas with similar underlying geology, this approach may improve prediction of arsenic risk down to the local level.

Geogenic arsenic in drinking water is a worldwide problem. For private well owners, testing (e.g., private or government laboratory) is the main method to determine arsenic concentration. However, the temporal variability of arsenic concentrations is not well characterized and it is not clear how often private wells should be tested. To answer this question, three datasets, two new and one publicly available, with temporal arsenic data were utilized: 6370 private wells from New Jersey tested at least twice since 2002, 2174 wells from the USGS NAWQA database, and 391 private wells sampled 14 years apart from Bangladesh. Two arsenic drinking water standards are used for the analysis: 10 µg/L, the WHO guideline and EPA standard or maximum contaminant level (MCL) and 5 µg/L, the New Jersey MCL. A rate of change was determined for each well and these rates were used to predict the temporal change in arsenic for a range of initial arsenic concentrations below an MCL. For each MCL and initial concentration, the probability of exceeding an MCL over time was predicted. Results show that to limit a person to below a 5% chance of drinking water above an MCL, wells that are ½ an MCL and above should be tested every year and wells below ½ an MCL should be tested every 5 years. These results indicate that one test result below an MCL is inadequate to ensure long-term compliance. Future recommendations should account for temporal variability when creating drinking water standards and guidance for private well owners.

A study was conducted to evaluate monitored natural attenuation (MNA) as a remedy for arsenic in groundwater at a former phosphate mining and manufacturing facility. The mineralogy, speciation, and lability of arsenic in phosphatic wastes present in soils were characterized using sequential extraction procedures, leaching experiments, batch adsorption tests, and microchemical speciation analysis. A PHREEQC‐based reactive transport model was also parameterized using these laboratory results, and it was used to evaluate the importance of identified attenuation mechanisms on arsenic concentrations along a vertical flow path from a shallow, alluvial aquifer to the underlying Floridan aquifer. Arsenic was found to occur in several chemical forms in phosphatic wastes, including unstable sulfide minerals, adsorbed surface complexes, and relatively insoluble phosphate and oxide minerals. Most arsenic was associated with stable minerals. The reactive transport model predicted that historical leaching of solid‐phase waste materials in soils would not have generated enough arsenic to explain the concentrations observed in downgradient groundwater; instead, the source of arsenic to groundwater was likely acidic and saline process water that infiltrated though unlined ponds and ditches during historical manufacturing operations. A key factor affecting the long‐term effectiveness of natural attenuation of arsenic in groundwater is the occurrence and stability of iron oxyhydroxides in aquifer sediments. According to laboratory and reactive transport model results, sufficient levels were found to be present at the site to effectively limit arsenic migration at concentrations exceeding drinking water standards in the future in the Floridan aquifer. This study presents the geochemical evaluations that are needed to satisfy EPA guidelines on determining whether or not MNA is an acceptable remedy for a site. It specifically details the characterization and modeling that were used to demonstrate effectiveness at a site where MNA was ultimately selected as the remedy for arsenic in groundwater.

Groundwater arsenic (As) contamination is a global public health concern. The high level of As exposure (100-1000 μg/L or even higher) through groundwater has been frequently associated with serious public health hazards, e.g., skin disorders, cardiovascular diseases, respiratory problems, complications of gastrointestinal tract, liver and splenic ailments, kidney and bladder disorders, reproductive failure, neurotoxicity and cancer. However, reviews on low-level As exposure and the imperative health effects are far less documented. The World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA) has set the permissible standard of As in drinking water at 10 μg/L. Considering the WHO and USEPA guidelines, most of the developed countries have established standards at or below this guideline. Worldwide many countries including India have millions of aquifers with low-level As contamination (≤50 μg/L). The exposed population of these areas might not show any As-related skin lesions (hallmark of As toxicity particularly in a population consuming As contaminated groundwater >300 μg/L) but might be subclinically affected. This review has attempted to encompass the wide range of health effects associated with chronic low-level As exposure ≤50 μg/L and the probable mechanisms that might provide a better insight regarding the underlying cause of these clinical manifestations. Therefore, there is an urgent need to create mass awareness about the health effects of chronic low-level As exposure and planning of proper mitigation strategies.

Populations exposed to arsenic in drinking water have an increased bladder cancer risk and evidence suggests that several factors may modify arsenic metabolism, influencing disease risk. We evaluated whether the association between cumulative lifetime arsenic exposure from drinking water and bladder cancer risk was modified by factors that may impact arsenic metabolism in a population-based case-control study of 1,213 cases and 1,418 controls. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between cumulative arsenic intake and bladder cancer stratified by age, sex, smoking status, body mass index (BMI), alcohol consumption and folate intake. P-values for interaction were computed using a likelihood ratio test. We observed no statistically significant multiplicative interactions although some variations in associations were notable across risk factors, particularly for smoking and BMI. Among former smokers and current smokers, those with the highest cumulative arsenic intake had elevated risks of bladder cancer (OR = 1.4, 95% CI: 0.96-2.0 and OR = 1.6, 95% CI: 0.91-3.0, respectively; while the OR among never smokers was 1.1, 95% CI: 0.6-1.9, p-interaction = 0.49). Among those classified as normal or overweight based on usual adult BMI, the highest level of cumulative arsenic intake was associated with elevated risks of bladder cancer (OR = 1.3, 95% CI: 0.89-2.0 and OR = 1.6, 95% CI: 1.1-2.4, respectively), while risk was not elevated among those who were obese (OR = 0.9, 95% CI: 0.4-1.8) (p-interaction = 0.14). Our study provides some limited evidence of modifying roles of age, sex, smoking, BMI, folate and alcohol on arsenic-related bladder cancer risk that requires confirmation in other, larger studies.

Arsenic in groundwater is a serious problem in New England, particularly for domestic well owners drawing water from bedrock aquifers. The overlying glacial aquifer generally has waters with low arsenic concentrations but is less used because of frequent loss of well water during dry periods and the vulnerability to surface-sourced bacterial contamination. An alternative, novel design for shallow wells in glacial aquifers is intended to draw water primarily from unconsolidated glacial deposits, while being resistant to drought conditions and surface contamination. Its use could greatly reduce exposure to arsenic through drinking water for domestic use. Hypothetical numerical models were used to investigate the potential hydraulic performance of the new well design in reducing arsenic exposure. The aquifer system was divided into two parts, an upper section representing the glacial sediments and a lower section representing the bedrock. The location of the well, recharge conditions, and hydraulic properties were systematically varied in a series of simulations and the potential for arsenic contamination was quantified by analyzing groundwater flow paths to the well. The greatest risk of arsenic contamination occurred when the hydraulic conductivity of the bedrock aquifer was high, or where there was upward flow from the bedrock aquifer because of the position of the well in the flow system.

BACKGROUND Arsenic induces neural tube defects in many animal models. Additionally, studies have shown that mice with specific genetic defects in folate metabolism and transport are more susceptible to arsenic-induced neural tube defects. We sought to determine whether 14 single-nucleotide polymorphisms in genes involved in folate metabolism modified the effect of exposure to drinking water contaminated with inorganic arsenic and posterior neural tube defect (myelomeningocele) risk. METHODS Fifty-four mothers of children with myelomeningocele and 55 controls were enrolled through clinical sites in rural Bangladesh in a case–control study of the association between environmental arsenic exposure and risk of myelomeningocele. We assessed participants for level of myelomeningocele, administered questionnaires, conducted biological and environmental sample collection, and performed genotyping. Inductively coupled plasma mass spectrometry was used to measure inorganic arsenic concentration in drinking water. Candidate single-nucleotide polymorphisms were identified through review of the literature. RESULTS Drinking water inorganic arsenic concentration was associated with increased risk of myelomeningocele for participants with 4 of the 14 studied single-nucleotide polymorphisms in genes involved in folate metabolism: the AA/AG genotype of rs2236225 (MTHFD1), the GG genotype of rs1051266 (SLC19A1), the TT genotype of rs7560488 (DNMT3A), and the GG genotype of rs3740393 (AS3MT) with adjusted odds ratio of 1.13, 1.31, 1.20, and 1.25 for rs2236225, rs1051266, rs7560488, and rs3740393, respectively. CONCLUSION Our results support the hypothesis that environmental arsenic exposure increases the risk of myelomeningocele by means of interaction with folate metabolic pathways. Birth Defects Research (Part A) 103:754–762, 2015. © 2015 Wiley Periodicals, Inc.

I. INTRODUCTION Drinking bottled water has become both increasingly popular and increasingly controversial. Annual U.S. consumption of bottled water tripled from 12 billion bottles in 2000 to 36 billion bottles in 2006 (Container Recycling Institute 2008). Per capita consumption of bottled water in 2010 was 28.3 gallons annually, exceeding the per capita amounts for milk (20.4 gallons), coffee (18.4 gallons), and tea (10.3 gallons), but less than the comparable amount for all sodas (44.7 gallons). (1) Bottled water has come under particular attack because of the perceived irrationality of the consumer choice. Some critics view bottled water as an entirely frivolous consumer good without any desirable product attributes. (2) They claim that those who drink bottled water are victims of hype and that bottled water is not superior on any dimension to tap water and can be riskier than tap water. Moreover, to the extent that bottled water is purified tap water, they suggest that there is often no taste difference. This article examines these critiques and provides an exploration of the private rationality of bottled water drinking. Despite the widespread claims of consumer irrationality in the media and by environmental groups, there has been little empirical attention paid to the assessment of whether there is a potentially sound basis for bottled water consumption. In this instance, as with many other personal consumption decisions and expressions of paternalistic concerns, individual preferences vary and critiques may be a form of second guessing the choices of others based on one's own preferences. However, irrespective of the heterogeneity of individual preferences, such critiques may nevertheless be valid if the consumption choices are driven by misperception of the attributes of the product by consumers. It is the soundness of consumer perceptions and the coherence of individual choice that we examine in this article. Whether consumers properly assess risks and how information affects these risk beliefs is of continuing interest in a variety of consumer choice contexts. Much attention has been devoted to tests of the perception of the risks of smoking, which are analyzed in Viscusi (1990), among others. Information about other less prominent hazards has also been shown to be influential in altering consumer behavior as in the case of consumer responses to mercury advisories for fish (Shimshack, Ward, and Beatty 2007). Our analysis is unique both in its focus on linkages between water quality experiences, risk beliefs, and precautionary behaviors from a nationally representative sample. There are several important antecedents in the literature that address issues that are relevant to the topics addressed here. This research has largely focused on arsenic risks in water, likely stimulated in part by the controversial U.S. Environmental Protection Agency (EPA) regulation reducing allowable arsenic levels in drinking water. (3) For instance, in a mail survey in 30 Minnesota communities with high levels of arsenic contamination in water, residents express adverse individual experiences with taste, color, and odor in the water even though arsenic is tasteless, odorless, and colorless (Cho, Easter, and Konishi 2010). While this result suggests that consumers apparently lack understanding of the determinants of arsenic risks, it also may reflect consumers' belief that sensory water characteristics on these dimensions can provide information with respect to risk components that cannot be readily monitored. After the study provided respondents with information on current and historical information of arsenic levels, only the taste attribute continued to play a significant role as a predictor of assessed arsenic risks (color and odor were no longer influential). The dominant role of taste in governing arsenic risk beliefs is consistent with the leading role that taste considerations play in our respondents' risk beliefs of water quality risks generally as well as their water usage decisions. …

Microbially mediated arsenic release from Holocene and Pleistocene Cambodian aquifer sediments was investigated using microcosm experiments and substrate amendments. In the Holocene sediment, the metabolically active bacteria, including arsenate-respiring bacteria, were determined by DNA stable-isotope probing. After incubation with 13 C-acetate and 13 C-lactate, active bacterial community in the Holocene sediment was dominated by different Geobacter spp.-related 16S rRNA sequences. Substrate addition also resulted in the enrichment of sequences related to the arsenate-respiring Sulfurospirillum spp. 13 C-acetate selected for ArrA related to Geobacter spp. whereas 13 C-lactate selected for ArrA which were not closely related to any cultivated organism. Incubation of the Pleistocene sediment with lactate favoured a 16S rRNA-phylotype related to the sulphate-reducing Desulfovibrio oxamicus DSM1925, whereas the ArrA sequences clustered with environmental sequences distinct from those identified in the Holocene sediment. Whereas limited As(III) release was observed in Pleistocene sediment after lactate addition, no arsenic mobilization occurred from Holocene sediments, probably because of the initial reduced state of As, as determined by X-ray Absorption Near Edge Structure. Our findings demonstrate that in the presence of reactive organic carbon, As(III) mobilization can occur in Pleistocene sediments, having implications for future strategies that aim to reduce arsenic contamination in drinking waters by using aquifers containing Pleistocene sediments.

Nanoscale Fe-Mn binary oxides loaded on zeolite (NIMZ) is synthesized and characterized. The as-synthesized adsorbent is amorphous with 126 m 2 /g surface area; it is effective for the adsorption of both As(III) and As(V) in synthetic groundwater. It has high adsorption capacities of 296.23 and 201.10 mg/g for As(III) and As(V), respectively. For the adsorption of 2 mg/L arsenic, the aqueous concentration quickly decreases to less than 10 lg/L within 30 min. During the adsorption of As(III), the in-aqueous measurement of As(V) shows a low concentration in the initial stage and disappears afterward. The fraction of As(V) on NIMZ gradually increases with time, proving the oxidation of As(III). The adsorption of As(III) and As(V) decreases with increasing pH. The anions of SiO 2� 3 ,H 2PO � 4 , and HCO � 3 significantly compete with arsenic for the adsorption sites. The inner- sphere surface complexes are formed by As(III) or As(V) with the hydroxyl groups on the surface of NIMZ. Water Environ. Res., 86, 147 (2014).

The distributional pattern of dissolved arsenic concentrations from landfill plumes can provide clues to the source of arsenic contamination. Under simple idealized conditions, arsenic concentrations along flow paths in aquifers proximal to a landfill will decrease under anthropogenic sources but potentially increase under in situ sources. This paper presents several conceptual distributional patterns of arsenic in groundwater based on the arsenic source under idealized conditions. An example of advanced subsurface mapping of dissolved arsenic with geophysical surveys, chemical monitoring, and redox fingerprinting is presented for a landfill site in New Hampshire with a complex flow pattern. Tools to assist in the mapping of arsenic in groundwater ultimately provide information on the source of contamination. Once an understanding of the arsenic contamination is achieved, appropriate remedial strategies can then be formulated. © 2013 Wiley Periodicals, Inc.*

Arsenic contamination of global water supplies has come to the forefront in policy decisions in recent decades. However, the effects of arsenic on lower trophic levels of insects inhabiting contaminated ecosystems are not well understood. One approach to document both acute and sublethal effects of toxicants like arsenic is to assay them in combination with microbial pathogens to evaluate shifts in survival curves of the test organisms. Larvae of Culex quinquefasciatus and Culex tarsalis were reared in water containing 0 or 1 000 μg/L of arsenate or arsenite. Fourth instars were then exposed to a range of doses of Bacillus thuringiensis subsp. israelensis (Bti) or Lysinibacillus sphaericus (Ls), with shifts in lethal concentrations determined. Arsenic accumulation in 4th instars was also quantified, and a relative growth index (RGI) calculated for the treatments and compared to controls. Larvae of both species accumulated between 4 447 ± 169 ng As/g and 6 983 ± 367 ng As/g, though RGI values indicated accumulation did not affect growth and development. In all cases, the LC50 's and LC90 's of Cx. quinquefasciatus exposed jointly with arsenic and Bti/Ls were higher than Cx. tarsalis. Cx. tarsalis reared in arsenite showed a significant reduction in their Bti LC90 values compared to the control, indicating a sublethal effect of Bti. When exposed jointly with Ls, arsenite was more toxic than arsenate in Cx. tarsalis. Overall, these results indicate tolerance of these Culex species to arsenic exposures, and why this may occur is discussed.

The processes of adsorption and co-precipitation at mineral surfaces during reactions with aqueous fluids play a critical role in controlling the mass transfer and bioavailability of nutrients and contaminants. Significant advances have been made in our understanding of these two processes through the application of synchrotron-based analytical techniques including X-ray Absorption Spectroscopy (XAS), X-ray surface scattering methods, X-ray fluorescence, and glancing incidence diffraction. Along with these methodologies, a wide range of other techniques involving infra-red spectroscopy, atomic-force microscopy, electron and particle beams have also contributed to understanding atomic-scale processes at mineral surfaces. Here, the basics of each of these synchrotron methods are introduced along with an illustrative example from the literature. The allied techniques are also discussed. After this introduction, two case studies dealing with major contemporary environmental problems that involve adsorption and co-precipitation are presented. The first concerns the mobility of arsenic in groundwater. Currently, dissolved arsenic species pose an environmental threat to millions of people. The second case study considers the speciation and uptake of uranium within UK radioactive waste sludge. Clean-up of these sludges is expected to be a challenging technological problem, and the insights provided through understanding the attachment of the uranium to the sludge minerals may be critical to devising a successful remediation strategy.

Hair arsenic concentrations were measured in 50 dogs living at Barrio Los Alamos, Gran Buenos Aires, Argentina, to evaluate the contamination risk in humans living in an area with arsenic levels higher than maximum allowed limit of 10 µg l−1. This region belongs to the zone in Argentina with Chronic Endemic Hydroarsenicism. Quantification of the samples was carried out using total reflection X-ray fluorescence technique after a sample preparation procedure. Independent of genre, age and breed, hair dogs from Los Alamos had significantly higher arsenic concentrations than a set of ten dogs used as blank coming from a free arsenic area. These found levels in hair indicated a chronic contamination in dogs and suggest similar presumption in humans. Results of this study encourage the potential of using pets as biomarkers of environmental metal contamination. Copyright © 2013 John Wiley & Sons, Ltd.

Toxic and carcinogenic effects of arsenic in drinking water continue to impact people throughout the world and arsenic remains common in groundwater at cleanup sites and in areas with natural sources. Advances in groundwater remediation are needed to attain the low concentrations that are protective of human health and the environment. In this article, we present the successful use of a permeable reactive barrier (PRB) utilizing sulfate reduction coupled with zero-valent iron (ZVI) to remediate the leading edge of a dissolved arsenic plume in a wetland area near Tacoma, Washington. A commercially available product (EHC-M®, Adventus Americas Inc., Freeport, Illinois) that contains ZVI, organic carbon substrate, and sulfate was injected into a reducing, low-seepage-velocity aquifer elevated in dissolved arsenic and iron from a nearby, slag-containing landfill. Removal effectiveness was strongly correlated with sulfate concentration, and was coincident with temporary redox potential (Eh) reductions, consistent with arsenic removal by iron sulfide precipitation. The PRB demonstrates that induced sulfate reduction and ZVI are capable of attaining a regulatory limit of 5 µg/L total arsenic, capturing of 97% of the arsenic entering the PRB, and sustaining decreased arsenic concentrations for approximately 2 years, suggesting that the technology is appropriate for consideration at other sites with similar hydrogeochemical conditions. The results indicate the importance of delivery and longevity of minimum sulfate concentrations and of maintaining sufficient dissolved organic carbon and/or microscale ZVI to precipitate FeS, a precursor phase to arsenic-bearing pyrite that may provide a stable, long-term sink for arsenic.

XPS measurements of coarse-grained and nanostructured nitinol (Ni 50.2Ti49.8) before and after chemical treatment in hydrofluoric acid (40% HF, 1 min) are presented. The nanostructured state, providing the excellent mechanical properties of nitinol, is achieved by severe plastic deformation. The near-surface layers of nitinol were studied by XPS depth profiling. According to the obtained results, a chemical treatment in hydrofluoric acid reduces the thickness of the protective TiO2 oxide layer and induces a nickel release from the nitinol surface and an arsenic contamination, and can therefore not be recommended as conditioning to increase the roughness of NiTi-implants. A detailed evaluation of the resulting toxicological risks is given. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. Copyright © 2012 Wiley Periodicals, Inc.

This study indicated important health and cancer risks through exposure to arsenic (As) in water sources. For this reason, the paper suggests that the consumption of drinking water highly contaminated by As should be stopped. Conventional technologies such as iron containing coagulants must be used to treat As‐contaminated water for As removal.

The fate of arsenic introduced to the environment as a result of the natural and human activities is an important issue. Surveys of arsenic typically involve sampling from a large area. Measuring arsenic concentrations in samples is expensive, and any improvement in the survey design is welcome. One way to improve efficiency in sampling is to make use of auxiliary information. Surveys of environmental pollution can be classed as surveys of rare populations, where there is a large area with a small polluted subarea. The rare population has many zeroes, or low, values, and contaminated subareas have non-zero, or high, values. Regression estimators or ratio estimators are undefined for those samples containing only information from the non-rare (zero-value) subpopulation (i.e., the non-contaminated subpopulation) in simple random sampling. In this paper, we introduce the modified regression estimators and their associated variance estimators for sampling designs which are suitable for rare populations, such as general inverse sampling and inverse sampling with unequal selection probabilities. We conducted a simulation study on the real rare population arsenic contamination in Kurdistan. The simulation results showed that the modified regression estimators are more efficient than the previous estimators. Copyright © 2011 John Wiley & Sons, Ltd.

A total of 243 groundwater samples from five Asian metropolitan areas (Bangkok, Jakarta, Manila, Seoul, and Taipei) were analysed to determine the status and mechanism of groundwater nitrate (NO3) and arsenic (As) pollution. The samples were divided into three groups based on the [NO3] versus [As]: high [NO3] (10–150 mg/l as NO3) with low [As] (0–5 µg/l), low [NO3] (0–10 mg/l) with high [As] (5–120 µg/l), and low [NO3] (0–10 mg/l) and [As] (0–5 µg/l). Groundwater from the Seoul hard-rock and Jakarta unconfined aquifer belonged to the first group, while that of the confined aquifer of Jakarta, Manila, and Bangkok belonged to the second group and the Taipei groundwater belonged to the last group. Comparison of the hydrogeological parameters and groundwater geochemistry among cities demonstrated that the redox conditions defined the behaviour of contaminants. In groundwater from Manila and Bangkok, where impermeable marine clay deposits comprise a large proportion of the surface geology, NO3 was depleted due to denitrification, while the As levels were higher as a result of the reducing conditions of the aquifer. Conversely, the relatively oxic environments in the Jakarta unconfined aquifers and the Seoul crystalline rock aquifer resulted in less denitrification and As dissolution. The results of this study suggest that [NO3] versus [As] diagrams are a useful method of evaluating the pollution types and contamination processes among the different urban groundwater systems while considering the hydrogeological settings. Copyright © 2011 John Wiley & Sons, Ltd.

Arsenic in groundwater has been a concern in South and Southeast Asia for more than a decade. We explore here the possibility that hydrogeologic factors recently shown to influence the distribution of arsenic might also affect the level of contamination of shallow (

Arsenic, an element found in nature, causes hazardous effects on living organisms. Meanwhile, natural compounds exhibit protective effects against hazardous substances. This study evaluated the effects of boron against arsenic-induced genotoxicity and altered biochemical parameters in rats. Thirty-five male Wistar albino rats were equally divided into five groups, and the experimental period lasted 30 days. One group was used as the control, and another group was treated with 100 mg/L arsenic in drinking water. The other groups were orally treated with 5, 10, and 20 mg/kg boron plus arsenic (100 mg/L via drinking water). Arsenic caused changes in biochemical parameters, total oxidant/antioxidant status, and DNA damage in mononuclear leukocytes. Moreover, it increased IFN-gamma, IL-1 beta, TNF-alpha, and NF kappa B mRNA expression levels in rat tissue. However, boron treatment improved arsenic-induced alterations in biochemical parameters and increases in DNA damage and proinflammatory cytokine gene expressions.

Arsenic concentrations exceeding the U.S. EPA's 10 μg/L standard are common in glacial aquifers in the midwestern United States. Previous studies have indicated that arsenic occurs naturally in these aquifers in association with metal-(hydr)oxides and is released to groundwater under reducing conditions generated by microbial oxidation of organic matter. Despite this delineation of the arsenic source and mechanism of arsenic mobilization, identification of arsenic-impacted aquifers is hindered by the heterogeneous and discontinuous nature of glacial sediments. In much of the Midwest, the hydrostratigraphy of glacial deposits is not sufficiently characterized to predict where elevated arsenic concentrations are likely to occur. This case study from southeast Wisconsin presents a detailed characterization of local stratigraphy, hydrostratigraphy, and geochemistry of the Pleistocene glacial deposits and underlying Silurian dolomite. Analyses of a single core, water chemistry data, and well construction reports enabled identification of two aquifers separated by an organic-rich aquitard. The upper, unconfined aquifer provides potable water, whereas arsenic generally exceeds 10 μg/L in the deeper aquifer. Although coring and detailed hydrostratigraphic characterization are often considered impractical, our results demonstrate that a single core improved interpretation of the complex lithology and hydrostratigraphy. This detailed characterization of hydrostratigraphy facilitated development of well construction guidelines and lays the ground work for further studies of the complex interactions among aquifer sediments, hydrogeology, water chemistry, and microbiology that lead to elevated arsenic in groundwater.

Arbuscular mycorrhizae (AM) are the most widespread mutualistic symbioses between the roots of most land plants and a phylum of soil fungi. AM are known to influence plant performance by improving mineral nutrition, protecting against pathogens and enhancing resistance or tolerance to biotic and abiotic stresses. The aim of this study was to investigate the frond proteome of the arsenic hyperaccumulator fern Pteris vittata in plants that had been inoculated with one of the two AM fungi (Glomus mosseae or Gigaspora margarita) with and without arsenic treatment. A protective role for AM fungi colonisation in the absence of arsenic was indicated by the down-regulation of oxidative damage-related proteins. Arsenic treatment of mycorrhizal ferns induced the differential expression of 130 leaf proteins with specific responses in G. mosseae- and Gi. margarita-colonised plants. Up-regulation of multiple forms of glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and enolase, primarily in G. mosseae-inoculated plants, suggests a central role for glycolytic enzymes in arsenic metabolism. Moreover, a putative arsenic transporter, PgPOR29, has been identified as an up-regulated protein by arsenic treatment.

Within the deltas of South Asia, widespread consumption of groundwater containing dangerous levels of arsenic adversely impacts tens of millions of people in Bangladesh, West Bengal, India, Cambodia, Vietnam, and Myanmar. This massive health crisis is the product of a confluence of processes initiated by the erosion of arsenic-bearing minerals in the Himalaya, transport of sediments containing arsenic-bearing iron oxides down the Brahmaputra–Ganges, Mekong, Irrawaddy and Red river systems, and deposition as deltaic sediments. Upon burial, dissolution of these arsenic-bearing iron-oxide minerals is triggered by reaction with organic carbon, releasing arsenic to the aquifer and producing aqueous concentrations that can exceed 1000 μg/L, 100 times the World Health Organization drinking water standard. These waters are the primary drinking water source for the majority of the people living in these low-lying regions of Asia. Although groundwater contamination has likely persisted for millennia on the Asian deltas, consumption of these waters became widespread in the 1970s as groundwater was tapped to avoid water-borne diseases in surface water bodies. Groundwater pumping for irrigation and other land use changes, including widespread rice cultivation, are now impacting the distribution of arsenic in (presently) unpredictable ways. Further, irrigation with arsenic-rich waters is decreasing rice yields and providing an additional pathway of human exposure. In general, deeper groundwater contains low levels of arsenic. Efforts must continue to focus on protecting this resource for human consumption.

Arsenic (As) is a highly toxic element and its presence in food is a matter of concern for the well-being of both animals and humans. Arsenic-contaminated groundwater is used in agriculture to irrigate crops for food and animal consumption with a potential contamination of the food chain. The purpose of this study was the evaluation of arsenic effect on radish tuber (Raphanus sativus L.). Experimental plots with sandy and clay-loamy soil were cultivated with radish and treated with three different concentrations of As water solution: 19, 44 and 104 µg/L. Magnetic resonance imaging was used to visualize the tuber structural changes, and the content of elements and the As amount were evaluated by inductively coupled plasma atomic emission spectroscopy. The data obtained demonstrate that As contamination in radish tuber is underlined with the dual approach. PRACTICAL APPLICATIONS The scope of this research is the evaluation of the effects on the toxicology and the morphology because of the arsenic (As) uptake by edible plants. The focus is on the contamination of the plant, which has implications for food safety and human health. The results obtained by magnetic resonance imaging and inductively coupled plasma atomic emission spectroscopy show that several changes of the internal structure occurred and that some parameters can be used as indicators of the As contamination in food.

The maximum contaminant level for arsenic was reduced by the U.S. Environmental Protection Agency (U.S. E.P.A.) for Drinking Water Standards from 50 micrograms per liter (µg/L) to 10 µg/L, effective January 23, 2006. The subject site is a double-lined sanitary landfill facility located in the mid-Atlantic region of the United States. Arsenic was reported above the maximum contaminant level in a downgradient monitoring well (MW-18) in July 2005. Since July 2005, arsenic levels in MW-18 fluctuated above and below 10 µg/L. This research focuses on determining whether reducing conditions in groundwater, enhanced by subsurface landfill gas emissions, were causing naturally-occurring arsenic to mobilize from the native variably-saturated vadose zone soils into groundwater. The groundwater data collected from the impacted well (MW-18) were compared to an upgradient well (MW-8) to determine whether significant differences existed during the time period of April 2004 to April 2007. Linear regression analysis was also used to determine whether other parameters had a significant relationship with the arsenic concentrations detected in MW-18. The groundwater located in MW-18 was consistently more reduced than groundwater located in the upgradient/background well MW-8, and this was most likely attributed to the presence of subsurface landfill gas in the area. According to the U.S. E.P.A., oxidation-reduction potential (ORP) values in groundwater less than 50 millivolts (mv) suggest that a reducing environment may be present. The data presented in this study indicate that arsenic can mobilize into groundwater under moderately reducing conditions, with ORP measurements averaging 53 mv.

Private wells are the source of drinking water for approximately 15% of households in the United States, but these wells are not regulated or monitored by government agencies. The well waters can contain arsenic, a known carcinogen that occurs in groundwater throughout the nation at concentrations that can exceed the Maximum Contaminant Level defined by the U.S. Environmental Protection Agency (10 ppb). In order to reduce arsenic exposure, homeowners can either rely on bottled water for drinking or install in-house water treatment systems for arsenic removal. Here, we document the arsenic levels associated with these options. We examined 24 different major bottled water brands and found that all have arsenic levels

Drinking arsenic-contaminated water leads to a series of health problems that has limited development for the largely poor rural people of Pakistan who are unable to afford bottled water, centralized treatment plants, or expensive water filter systems. This paper reviews the available appropriate technologies for the removal of arsenic in drinking water to assist in just sustainable development in Pakistan. Several technologies were found to be both technically- and economicallyviable and support the large-scale deployment of these small-scale, appropriate technologies. The economic viability determined in this study was based on both first costs and operating costs. The cost of implementing such technologies for an individual Pakistani family is made acceptable with the use of local materials, which the family may already own. For example, systems using sand and iron nails in the filters, and which are placed in plastic buckets that are already in common use in the villages, drive down the overall costs of the technology and put it in the reach of even the most destitute. This study found that complications from the variability of local supplies result in the need to identify the locally most appropriate solution from both a technical and economic standpoint. This review article should be helpful for any practitioner in determining the locally optimal solution for the removal of arsenic from drinking water in Pakistan.

Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans. Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite, the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified.

The forthcoming introduction of lower standards for arsenic in drinking water requires new technologies for arsenic removal. We report the development of an electrochemical unit for remediating domestic water supplies for homes without municipally treated water. Electrolysis in a two-anode system provides oxidants to convert As(III) to As(V) in situ, and a sacrificial anode to deliver iron into solution. Conditioning tanks after each electrolysis step ensure completion of the chemical reactions. At the pH of domestic water, As(V) co-precipitates with Fe(OH)3; subsequent filtration leaves

Inorganic arsenic is a potent human carcinogen and general toxicant. More than one hundred million people are exposed to elevated concentrations, mainly via drinking water, but also via industrial emissions. Arsenic is metabolized via methylation and reduction reactions, methylarsonic acid and dimethylarsinic acid being the main metabolites excreted in urine. Both inorganic arsenic and its methylated metabolites easily pass the placenta and both experimental and human studies have shown increased risk of impaired foetal growth and increased foetal loss. Recent studies indicate that prenatal arsenic exposure also increases the risk of adverse effects during early childhood. There is a growing body of evidence that the intrauterine or early childhood exposure to arsenic also induces changes that will become apparent much later in life. One epidemiological study indicated that exposure to arsenic in drinking water during early childhood or in utero was associated with an increased mortality in young adults from both malignant and non-malignant lung disease. Furthermore, a series of experimental animal studies provide strong support for late effects of arsenic, including various forms of cancer, following intrauterine arsenic exposure. The involved modes of action include epigenetic effects, mainly via DNA hypomethylation, endocrine effects (most classes of steroid hormones), immune suppression, neurotoxicity, and interaction with enzymes critical for foetal development and programming.

The study area is located on the western part of the alluvium-filled gap between the Rajmahal hills on the west and the Garo hills on the east. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternary alluvial sediments. Three hydrochemical facies with distinct characteristics have been identified which are dominated in general by alkaline earths and weak acids. The major-ion chemistry of the area is controlled by weathering of silicate minerals, rainfall recharge, ion-exchange processes and anthropogenic activities such as irrigation return flow and the application of inorganic fertilizers and pesticides. A stoichiometric approach suggests that mineral dissolution and anthropogenic activities contribute 79% and 21% of the total cations dissolved in groundwater. Principal component analysis (PCA) of 42 groundwater samples using 13 chemical parameters indicates that the combined processes of recharge of groundwater from rainfall, sediment water interaction, groundwater flow, infiltration of irrigation return water (which is arsenic rich due to the use of arsenic-bearing pesticides, wood preservatives, etc. and the pumping of arsenic-rich groundwater for agriculture purpose), oxidation of natural or anthropogenic organic matter and the reductive dissolution of ferric iron and manganese oxides play a key role in the evolution of groundwater in the study area. Factor 2 scores, associated with the infiltration of irrigation return water and spatial distribution of arsenic concentration reveal that the groundwater of the municipal area will not be affected by arsenic in the future in spite of heavy groundwater abstraction. Another PCA with geologic, geomorphic, anthropogenic, geochemical and landuse factors indicates that arsenic concentration in groundwater increases with increasing area of mango orchards, sand lithofacies and nitrate and decreases with increasing distance of paleochannel from the monitored well and depth of bore wells. High loading on nitrate may be attributed to the use of fertilizer, pesticides, etc. in mango orchards and agricultural land. High loadings on log pCO2, mango orchards (with negative sign) and phosphate (with positive sign) indicate that mango orchards provide the organic waste material which is decomposed to form organic carbon. The organic carbon undergoes oxidative carbon degeneration by different oxidants and increases the concentration of CO2 in the aquifer. The reducing condition thus developed in the aquifer helps to dissolve the arsenic adsorbed on iron hydroxide or oxy-hydroxide coated margins of sand, iron rich heavy mineral grain margins, clay minerals and Fe–Mn concretions present in the aquifer matrix. Copyright © 2007 John Wiley & Sons, Ltd.

We investigated the influence of flooding and chronic arsenic contamination on ecosystem structure and function in a headwater stream adjacent to an abandoned arsenic (As) mine using an upstream (reference) and downstream (mine-influenced) comparative reach approach. In this study, floods were addressed as a pulse disturbance, and the abandoned As mine was characterized as a press disturbance. We further addressed chronically elevated As concentrations as a ramp disturbance, in which disturbance intensity was ramped by increasing proximity to the As source. Stream ecosystem structure and biogeochemical functioning were characterized monthly over a period ranging from July to December 2004. Influence of the press disturbance was evident in the mine-influenced reach, where As concentrations (254 6 39 m gL 21) were more than 30 times higher than in the reference reach (8 6 1 m gL 21). However, in almost all cases the presence of the abandoned As mine appeared to exert little influence on reach-scale measures of ecosystem structure and function (e.g., organic matter [OM] standing crops, phosphorus [P] uptake). Conversely, floods significantly influenced OM standing stock in both study reaches. Interactions between press and pulse disturbances influenced P uptake in the mine-influenced reach. Within the mine-influenced reach, P uptake across a gradient of As concentrations correlated with Michaelis–Menton models of enzyme kinetics in the presence of a competitive inhibitor. These results indicate that As competitively inhibits P uptake by microbial assemblages.

Churchill County, Nevada, has approximately 23,000 residents, among whom an estimated 13,500 relied on private wells for water supply in 2002. This study examined exposure to arsenic in water supplies among residents with private domestic wells and factors related to householder choice to consume tap water. It compared opinions and concerns about water quality with consumption habits and observed concentrations from tap water samples. The results from 351 households indicated that a majority (75 percent) of respondents consumed tap water and that a minority (38 percent) applied treatment. Approximately 66 percent of those who consumed tap water were exposed to concentrations of arsenic that exceeded 10 ppb. Water consumption was related to application of treatment. Among 98 respondents who were not at all concerned about the health effects of aqueous arsenic, 59 (60 percent) reported consuming tap water with concentrations of arsenic exceeding 10 ppb. Conversely, among 86 respondents who were highly concerned about arsenic, 33 (37 percent) consumed tap water with concentrations of arsenic exceeding 10 ppb. Results from a national sampling effort showed that 620 of 5,304 private wells sampled (11.7 percent) had arsenic concentrations above 10 ppb. The paradox of awareness of arsenic in water supplies coupled with consumption of aqueous arsenic in concentrations greater than 10 ppb may be common in other parts of the nation. Enhanced educational efforts, especially related to tap water sampling and explanations of efficacy of available treatment, may be useful means of reducing exposure through private water supplies.

Research interest in speciation of arsenic stems from its species dependent behavior in the environment and in living organisms. The complexity of the matrix to be analyzed and low concentrations of target arsenic species that may be labile or difficult to chromatogram, indicate that a suitable pre-treatment methodology is required. This study investigated the usefulness of chelation solvent extraction - high performance liquid chromatography (CSE-HPLC) for the speciation of arsenic in water. It involved reacting arsenic with the chelant known for its affinity towards arsenic, followed by extraction, separation, and identification of the arsenic-chelant-arsenic complex. Arsenic species having different physicochemical properties were investigated. Species, such as, AS 2 O 3 , AS 3 O 5 , KH 2 ASO 4 , Na 2 HASO 4 , and NaASO 2 were detected as a group of closely eluted peaks with different retention times and spectral properties, whereas, the organic arsenic species CH 3 Na 2 ASO 3 , o-arsanilic acid, roxarson and triphenyl arsine separated quite well on the EnviroseP-CM HPLC column. Key method parameters, such as, type of HPLC column, composition of mobile phase and organic solvents affecting peak resolution and sensitivity were optimized. Real environmental matrices contaminated with arsenic were analyzed under varying wavelengths (λ max = 190, 210, 220, 234, 244, and 282 nm), with good precision. Different arsenic species were detected in these samples with excellent background and signal-to-noise ratios demonstrating the robustness of the method. The detection limit, reproducibility, selectivity, accuracy, and dynamic range of the calibration curves were evaluated.

Arsenic in drinking water represents a major public health concern globally, with tens of millions of people thought to be consuming unsafe amounts of As daily. Groundwater is particularly vulnerable to As contamination, and one geochemical environment conducive to natural mobilization of As is found in shallow alluvial Holocene aquifers. Bacterial consumption of organic matter in these aquifers creates anoxic conditions, leading to dissimulatory reduction of Fe oxides. In these environments, dissolved As and Fe often co-occur. While As(III) is thermodynamically favored under these conditions, As(V) often is found as well. Concentrations of dissolved As(V) and Fe(II) can be constrained by the precipitation of ferrous arsenate solid phases such as symplesite [Fe(II) 3 (As(V)O 4 ) 2 ·8H 2 O]. We present a new solubility product for symplesite (pK so = 33.25) based on controlled laboratory precipitation experiments. Using this solubility product, we conducted equilibrium geochemical modeling using one of the most extensive groundwater data sets from Bangladesh to show that a number of water samples are oversaturated with a variety of solid phases, including siderite, calcite, rhodochrosite, vivianite, and symplesite. Symplesite or other ferrous arsenate solid phases could be a significant sink for As(V) and Fe(II) in Bangladesh and other countries with similar geochemical environments. Symplesite could also control As(V) solubility in extreme environments such as alkaline lakes or in brines used for regeneration of anion exchange resins.

Arsenic (As) is a highly toxic metalloid found in ground and surface water. Arsenic contamination in drinking water leads to harmful effects on human health. To eliminate arsenic from drinking water, several technologies such as coagulation, adsorption, ion exchange, filtration, membrane processes, etc., have been used. In this study, three technologies were evaluated for arsenic removal. Results from batch kinetic experiments showed that iron coated sand (IOCS-2) can remove more than 90% of As from synthetic water. Experiments were conducted with three different pH values (6, 7, and 8) and an initial As concentration of 260 μg/L. A new material, developed in this study, namely iron coated sponge (IOCSp), was found to have a high capacity in removing both As (V) and As (III). Each gram of IOCSp adsorbed about 160 μg of As within a 9-hour contact period of IOCSp with As solution. Low pressure nanofiltration removed more than 94% of As from an influent containing 440 μg/L As. The applied pressure was varied from 85 to 500 kPa. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A regional assessment of the arsenic (As) contamination scenario in shallow tube wells (depth < 150 m) of western Bangladesh is presented. Comparisons are made in light of bulk geological differences (Pleistocene versus Holocene deposits/northwest versus southwest) and As measurement protocols (field kit (FK) versus atomic absorption spectroscopy (AAS)). Our As database comprised the following: (1) the nationwide As survey completed in 1999 by the British Geological Survey in collaboration with the Department of Public Health Engineering (DPHE); and (2) a regional As survey conducted in southwest Bangladesh by the Japan International Cooperation Agency in collaboration with DPHE in 2002. First, we characterize the error structure of the semi-quantitative FK As measurements using collocated AAS As measurements as reference from a set of 307 wells located in southwest Bangladesh. The depth distribution of As is identified using a very dense cluster of 2963 wells over a 560 km2 domain. The probability of the FK method for successful detection of a well sample as unsafe (safe) was found to be 96·9% (34·1%) and 95·2% (80·3%) for the World Health Organization (WHO) and Bangladesh safe limits, respectively. Similarly, the probability of false alarms and false hopes for WHO (Bangladesh) safe limits were found to be 3·1% (4·8%) and 87·5% (19·7%), respectively. The depth at which the highest fraction of wells exceeding a given safe limit occurred could still be inferred correctly by FK measurements. A simple bias adjustment procedure on FK As data did not result in a more accurate characterization of depth distribution of As. This indicated that simple error statistics are inadequate for advancing the utility of FKs; rather, an understanding of the complex and multidimensional error structure is required. Regional anisotropy in the spatial dependence of As for the northwest was found to be stronger than the southwest. The correlation length for As concentration in the east–west direction of northwest Bangladesh (i.e. across major river floodplains) was found to be almost twice (158·80 km) that of the north–south direction (along the major axis of Pleistocene deposits) (78·21 km). For the southwest region, the ratio of east–west to north–south correlation lengths ranged from 1·40 to 1·51. For the northwest region, because it is well known to have the lowest concentrations of As countrywide, knowledge of this anisotropy appears to suggest the need for drilling twice as many remediation deep wells in the proximity of an unsafe shallow well in the north–south direction than in the east–west direction. Findings from this study are potentially useful in setting priority areas for emergency testing, distributing remediation resources equitably and formulating a regional water resources strategy for western Bangladesh. Copyright © 2005 John Wiley & Sons, Ltd.

The Safe Drinking Water Act of 1974 regulates water quality in public drinking water supply systems but does not pertain to private domestic wells, often found in rural areas throughout the country. The recent decision to tighten the drinking water standard for arsenic from 50 parts per billion (ppb) to 10 ppb may therefore affect some households in rural communities, but may not directly reduce health risks for those on private wells. The article reports results from a survey conducted in a U.S. arsenic hot spot, the rural area of Churchill County, Nevada. This area has elevated levels of arsenic in groundwater. We find that a significant proportion of households on private wells are consuming drinking water with arsenic levels that pose a health risk. The decision to treat tap water for those on private wells in this area is modeled, and the predicted probability of treatment is used to help explain drinking water consumption. This probability represents behaviors relating to the household's perception of risk.

Although the qualities of the river water and the sediments of the river Elbe have greatly improved over the past twenty years, both the suspended matter and the sediments are still contaminated with heavy metals and arsenic (HM). This contamination exceeds the action values specified in the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV). The status of floodplain soil contamination with HM along the entire German alluvial Elbe was investigated and evaluated, based on former research activities and recently performed analyses after the extreme flood event in August 2002 and the subsequent winter flooding. The section downstream of the river Mulde inflow was contaminated much higher than the upstream section. With the installation of permanently marked observation areas a tool for soil quality monitoring has been established for the future. Die hochwasserbedingte Belastung der Auen mit Schwermetallen und Arsen entlang der Elbe Obgleich sich die Flusswasser- und Sedimentqualitat der Elbe in den letzten 20 Jahren erheblich verbessert haben, sind die Schwebstoffe und schwebstoffburtigen Sedimente immer noch hoch mit Schwermetallen belastet. Dies fuhrt bei Bodenbildungen aus diesen Substraten haufig zur Uberschreitung der in der Bundesbodenschutz- und Altlastenverordnung (BBodSchV) festgelegten Masnahmewerte. Basierend auf fruheren Untersuchungen und aktuellen Erhebungen wahrend des extremen Hochwassers vom August 2002 und des folgenden Winterhochwassers wurde der gegenwartige Belastungsstatus der Boden in den Uberflutungsgebieten entlang der gesamten deutschen tidefreien Elbe ermittelt und bewertet. Dabei war der Flussabschnitt unterhalb der Muldemundung wesentlich hoher als der oberhalb gelegene belastet. Durch die Anlage dauerhaft markierter Beobachtungsflachen wird es ermoglicht, in Zukunft Veranderungen des Stoffbestandes exakt zu erfassen.

The Colline Metallifere in SW Tuscany are characterized by strong anomalies in arsenic concentrations and distribution. The area is sparsely populated and largely wild, though it has been subject to human impact due to mining and metal processing since Etruscan and Roman times. In the Middle Ages it was exploited intensively for silver and copper. Until 1995, pyrite (FeS2) was mined and roasted to produce sulphuric acid and iron. Hypotheses based on geological and mineralogical factors formulated in the last 20 years have failed to explain the peculiar distribution of arsenic in the Colline Metallifere. Here we report preliminary results of widespread sampling and analysis of the fluvial sediments of rivers originating in this mining area. The data was analysed in relation to the archaeological features of the area, since the presence of ancient mining and ore processing sites can shed light on the peculiar distribution of arsenic. Comparison of data from two rivers and their respective contaminated and uncontaminated coastal lagoons also clarified the general mechanisms of arsenic mobility, pinpointing the source of arsenic contamination. The study methods also promise to be useful for discovering unknown archaeological sites.

A potentiometric flow system has been developed for the direct determination of arsenic(V) in water samples after on-line preconcentration in a minicolumn packed with a new adsorbent material selective to As(V). Iron oxyhydroxide embedded in silica gel was synthesized and used simultaneously as adsorbent material in the minicolumn and as selective component in a tubular potentiometric electrode. In the first step, the sample solution is mixed on-line with phosphate buffer of pH 7 and pumped through the minicolumn to adsorb As(V). The insertion of the minicolumn in the mobile section of a homemade injector-commutator allows to relocate the minicolumn to desorb the retained As(V) in the second step. The desorption is maximum in the presence of 0.1 M phosphate of pH 12. Maximum response of the tubular selective membrane is achieved in phosphate buffer of pH 7. On-line oxidation of As(III) to As(V) by iodine (I3 � ) in the presence of phosphate buffer of pH 7 allows the determination of total As as As(V) and then the speciation of inorganic arsenic, since As(III) can be estimated as the difference between total As and As(V). In the optimized experimental conditions, a linear range of 40 – 500 m gL � 1 for As(V), and detection limits of 30.6 and 38.6 m gL � 1 for As(V) and total As, respectively, were obtained.The flow system has been successfully applied to the determination of inorganic arsenic species in groundwater samples collected in areas affected by arsenic contamination. Relative standard deviation of replicated determinations of As in groundwater samples was always below 5%.

The presence of arsenic in tubewell water has been identified as a major health problem in Bangladesh. The Bangladesh Government, with international assistance, is attempting to mitigate the effects of arsenic by a major programme of tubewell water testing and education about arsenic and how its ingestion can be avoided. In early 2000 the first nationally representative cluster sample survey of water use in Bangladesh found that knowledge of arsenicosis remained low, tubewell water remained the dominant source of rural water, and few people knew if their tubewell was safe from arsenic contamination or alternatively treated it for arsenic. This paper reports on a follow-up survey of the earlier study population to determine change over two years, and thus for the first time allows a measure of change at the national level. Awareness that there might be something wrong with tubewell water had risen markedly, especially among women respondents. However, there had been only a minor increase in the proportion reporting that they had changed water sources. This indicates a lack of a clear message about the risks involved, and about how to respond to the problem. The health authorities lack good information as to the real dangers involved, and the most appropriate interventions, both in technical terms and in terms of economic and social acceptability. In the absence of such information, the most effective strategy may be to promote more rapid testing of wells and to encourage people to switch wells. Copyright © 2005 John Wiley & Sons, Ltd.

Arsenic contamination of groundwater has long been reported in the Mushidabad district of West Bengal, India. We visited 13 arsenic-affected families in the Makrampur village of the Beldanga block in Mushidabad during 18-21 December 2001 and collected five shallow tubewell-water samples used general household purposes, four deep tubewell-water samples used for drinking and cooking purposes, and 44 urine samples from those families. The arsenic concentrations in the five shallow tubewell-water samples ranged from 18.0 to 408.4 ppb and those in the four deep tubewell-water samples were from 5.2 to 9.6 ppb. The average arsenite (arsenic(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate (arsenic(V)) in urine were 28.7 ng mg -1 , 168.6 ng mg -1 , 25.0 ng mg -1 and 4.6 ng mg -1 creatinine respectively. The average total arsenic was 227.0 ng mg -1 creatinine. On comparison of the ratio of (MMA + DMA) to total arsenic, the average proportion was 86.7 ± 9.2% (mean plus/minus to residual standard deviation, n = 43). The exception was data for one boy, whose proportion was 8.0%. One woman excreted the highest total arsenic, at 2890.0 ng mg -1 creatinine. When using 43 of the urine samples (the exception being the one sample obtained from the boy) there were significantly positive correlations (p < 0.01) between arsenic(III) and MMA, between arsenic(III) and DMA and between MMA and DMA.

Household water treatment is the decentralized treatment of drinking water in the home and safe storage is the protection of drinking water in specially designated household storage vessels. Even for the 50% of people worldwide with a tapped water supply, safety is not always assured. In such homes, household treatment units improve the aesthetics and/or remove harmful contaminants. Homes lacking a tapped drinking water supply are more likely to bear the burden of water-related illnesses: 3.4 million deaths are water related; 1.4 million children die annually of diarrhea—the third highest cause of illness and sixth highest cause of mortality globally; and 1.1 billion—or about one in six people globally—lack access to improved drinking water. For these people, household water treatment and safe storage may be their main barrier in the prevention of water-related illnesses, and evidence shows that household treatment and safe storage systems are capable of dramatically improving the microbial quality of drinking water and reducing diarrheal and other water-related diseases and death. In the decade to come, we will witness innovation and scale-up of these systems from hundreds to thousands to millions to meet the enormous global need for clean drinking water. Keywords: household water treatment; safe household water storage; point-of-use; point-of-entry; microbial contamination; arsenic contamination; fluoride contamination; household chlorination; household filters; water-related diseases; diarrheal diseases; global burden of disease; rural water supply; water treatment processes