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Reliability of a Commercial Kit To Test Groundwater for Arsenic in Bangladesh
Abstract
A comparison of field and laboratory measurements of arsenic in groundwater of Araihazar, Bangladesh, indicates that the most widely used field kit correctly determined the status of 88% of 799 wells relative to the local standard of 50 microg/L As. Additional tests showthatthe inconsistencies, mainly underestimates in the 50-100 microg/L As range, can be avoided by increasing the reaction time from 20 to 40 min. Despite this limitation, the field data already compiled for millions of wells by the Bangladesh Arsenic Mitigation and Water Supply Project, in combination with information on well location and depth, should prove to be extremely useful to prioritize interventions in thousands of affected villages.
... Although laboratory systems are highly sensitive, they are unsuitable for field measurements. A field test kit based on the color reaction of arsine with mercuric bromide had been used for blanket groundwater testing in Bangladesh, and the detection limit was 50-100 μg/L under field conditions (Rahman et al., 2002;van Geen et al., 2005). Arsenic is naturally present in rocks and sediments that form aquifers tapped for drinking water (see Fig. 5). ...
... Although most wells remained safe over the 3 years, the incidents of large fluctuation were hard to predict. A period analysis is still necessary for all wells for risk management (Ravenscroft et al., 2006;Sengupta et al., 2006;van Geen et al., 2005). Meanwhile, additional evaluation was carried out to study temporal variability of water chemistry in deep and shallow aquifers in the same area (Dhar et al., 2008). ...
... For quantitative analysis, the color of the test strips is compared with a color chart to estimate inorganic arsenic to the concentration near the MCL level (Spear et al., 2006). Most tests require incubation from 15 to 30 min according to manufacturer's recommendations (Spear et al., 2006), although there have been reports of improved results at lower concentrations when test times are increased (van Geen et al., 2005). These colorimetric test kits have found application in large field testing with mixed results (Rahman et al., 2002;van Geen et al., 2005). ...
Biosensors for monitoring water pollutants: a case study with arsenic in groundwater
1 Introduction
1.1 The changing profile of water pollution
1.2 Sources of water pollution
1.2.1 Nutrient pollution
1.2.2 Accidental spills
1.2.3 Natural pollution sources: the case of arsenic pollution
2. Monitoring of arsenic in groundwater
2.1 Managing groundwater contamination by arsenic is limited by analysis
2.1.1 Ground water as the most important resource
2.2 Factors that may influence the concentration in water
2.21 Arsenic concentration is dependent on the dynamics of mobilization and sequestration
2.2.2 Analysis of arsenic for nonpoint source pollution in groundwater
2.2.3 Analysis of arsenic for point source pollution in groundwater
2.2.4 Current field test tools and applications
3. Biosensors for monitoring arsenic in water
3.1 Biosensor technology
3.1.1 Common biorecognition elements
3.1.1.1 Affinity-binding elements
3.1.1.2 Enzymes
3.1.1.3 Whole cells
3.1.2 Transduction methods
3.1.2.1 Change in temperature
3.1.2.2 Change in mass
3.1.2.3 Change in electrical properties
3.1.2.4 Electrochemical methods
3.1.2.5 Optical methods
3.2 Biosensors for arsenic detection
3.2.1 Bioaffinity biosensors
3.2.2 Enzymatic biosensors
3.2.3 Whole cell biosensors
3.3 Biosensors for field monitoring
4. Contaminants of emerging concern and future priorities
4.1 Source, fact and transport of CECs
4.2 Detecting CEC in the environment
5. Conclusions.
... Well water samples were collected in 20-mL polyethylene scintillation vials and then acidified with high-purity Optima HCl for at least 48 hours before analysis to ensure re-dissolution of any iron oxides ). Samples were diluted 1:10 in a solution spiked with 73Ge and 74Ge for internal drift correction and analyzed for As by high-resolution inductively-coupled plasma mass spectrometry (HR ICP-MS) (Cheng et al. 2004;van Geen et al. 2005a). The detection limit of the method was typically 0.2 µg/L. ...
... The test involved mixing of prepackaged sulfamic acid and zinc powder with 50 mL of well water sample. The mixture eventually generated arsine gas (AsH 3 ), which is entrained with H 2 bubbles emanating from the acidified sample and trapped by a strip of paper impregnated with mercuric bromide (van Geen et al. 2005a). A previous study showed that this specific procedure could underestimate 50-100 µg/L As range and recommended a modification of the procedure by changing the reaction time from 20 minutes to 40 minutes (van Geen et al. 2005a). ...
... The mixture eventually generated arsine gas (AsH 3 ), which is entrained with H 2 bubbles emanating from the acidified sample and trapped by a strip of paper impregnated with mercuric bromide (van Geen et al. 2005a). A previous study showed that this specific procedure could underestimate 50-100 µg/L As range and recommended a modification of the procedure by changing the reaction time from 20 minutes to 40 minutes (van Geen et al. 2005a). At the end of the 40 minutes reaction time, we observed the intensity of the color of the orange-brown circle on the strip and compared it visually with a reference scale of several colored readings corresponding to As concentrations of 0, 10, 25, 50, 100, 250, and 500 µg/L. ...
Chronic exposure to well water arsenic (As) remains a major rural health challenge in Bangladesh and some other developing countries. Many mitigation programs have been implemented to reduce As exposure although evaluation studies for these efforts are rare in the literature.
This study estimates associations between a school-based intervention and various outcome measures of As mitigation.
We recruited 840 children from 14 elementary schools in Araihazar, Bangladesh. Teachers from 7 schools were trained on an As education curriculum, whereas the remaining seven schools without any training formed the control group. Surveys, knowledge tests and well-water testing were conducted on 773 children both at baseline and post-intervention follow-up. Urine samples were collected from 210 children from four intervention schools and the same number of children from four control schools. One low As (<10 μg/L) community well in each study village was ensured during an 18-month intervention period.
After adjustment for the availability of low As wells and other socio-demographic confounders, children receiving the intervention were five times more likely to switch from high to low As wells (p<0.001). We also observed a significant decline of urinary arsenic (UAs) (p=<0.001) (estimated b = -214.9; 95% CI: -301.1, -128.7 µg/g Cr) among the children who were initially drinking from high As wells (>Bangladesh standard of 50 μg/L) and significantly improved As knowledge attributable to the intervention after controlling for potential confounders.
These findings offer strong evidence that school-based intervention can effectively reduce As exposure in Bangladesh by motivating teachers, children and parents.
... 21 Hach reports that the EZ test detects 90 percent of arsenic present as arsenate (As(V)) and 100 percent of arsenic present as arsenite (As(III)) (HACH n.d.). Field performance may be somewhat lower(Steinmaus et al. 2006;van Geen et al. 2005). Before collecting samples to test for arsenic from wells, enumerators pumped the well the same number of times as the depth of the tubewell. ...
... Before collecting samples to test for arsenic from wells, enumerators pumped the well the same number of times as the depth of the tubewell. 22van Geen et al. (2005) recommend leaving the test for 40 minutes, instead of the manufacturer-recommended 20 minutes.Using only the manufacturer-recommended 20 minutes may have led us to underestimate arsenic concentrations. 23 Arsenite (As(III)) oxidizes rapidly to arsenate (As(V)) in stored water. ...
... A recent comparative analysis between several types of kits concluded that improved precision and accuracy are necessary to employ kits for health-related decision making (Reddy et al., 2020). In contrast, it has been argued that existing kits have been effective in identifying arsenic contaminated wells van Geen et al., 2002van Geen et al., , 2005. Testing all wells in Bangladesh, including new wells that continue to be installed, in the laboratory is unrealistic. ...
... Additionally, the spatial heterogeneity-which is critical for effective well switching-across the upazilas (sub-districts) in Bangladesh is also comparable to Araihazar (Jamil et al., 2019). Although the testing under BAMWSP underestimated the number of high As wells (van Geen et al., 2005), the similarity in the number of well with As > 50 μg/L and in the spatial heterogeneity of groundwater arsenic concentration suggest that the findings presented here are relevant across the country. The number of wells has increased rapidly in Bangladesh in the last 10 years (Jamil et al., 2019), and most of these wells are untested for As. ...
Well‐switching programs in Bangladesh have successfully lowered arsenic exposure. In these programs, households switch from wells that are labeled “unsafe” to nearby wells labeled “safe,” but these designations are usually based on inherently inaccurate field kit measurements. Here, we (a) compare the efficacy of field‐kit measurements to accurate laboratory measurements for well switching, (b) investigate the potential impact on well switching of the chosen “safe” threshold, and (c) consider the possible benefits of providing more detailed concentration information than just “safe” and “unsafe.” We explore different hypothetical mitigation scenarios by combining two extensive data sets from Araihazar Bangladesh: a blanket survey of 6595 wells over 25 km² based on laboratory measurements and 943 paired kit and laboratory measurements from the same area. The results indicate that the decline in average arsenic exposure from relying on kit rather than laboratory data is modest in relation to the logistical and financial challenge of delivering exclusively laboratory data. The analysis further indicates that the 50 μg/L threshold used in Bangladesh to distinguish safe and unsafe wells, rather than the WHO guideline of 10 μg/L, is close to optimal in terms of average exposure reduction. We also show that providing kit data at the maximum possible resolution rather than merely classifying wells as unsafe or safe would be even better. These findings are relevant as the government of Bangladesh is about to launch a new blanket testing campaign of millions of wells using field kits.
... 21 Hach reports that the EZ test detects 90 percent of arsenic present as arsenate (As(V)) and 100 percent of arsenic present as arsenite (As(III)) (HACH n.d.). Field performance may be somewhat lower(Steinmaus et al. 2006;van Geen et al. 2005). Before collecting samples to test for arsenic from wells, enumerators pumped the well the same number of times as the depth of the tubewell. ...
... Before collecting samples to test for arsenic from wells, enumerators pumped the well the same number of times as the depth of the tubewell. 22van Geen et al. (2005) recommend leaving the test for 40 minutes, instead of the manufacturer-recommended 20 minutes.Using only the manufacturer-recommended 20 minutes may have led us to underestimate arsenic concentrations. 23 Arsenite (As(III)) oxidizes rapidly to arsenate (As(V)) in stored water. ...
Health, and in turn income and welfare, depend on access to safe drinking water. Although the majority of rural households worldwide obtain drinking water from community water sources, there is limited evidence about how effectively these sources provide safe drinking water. This study combines a randomized experiment with water quality testing to evaluate the impact of a program that provides community deep tubewells in rural Bangladesh. The program reduces exposure to arsenic, a major natural pollutant, but not fecal contamination. Households may use fewer sources with fecal contamination, but any such effects are offset by recontamination through transport and possibly storage. The results suggest that while community deep-tubewell construction programs may reduce exposure to arsenic in Bangladesh, reducing exposure to fecal contamination may require interventions that go beyond community sources.
... The 20 min reaction time recommended by the kit instructions was subsequently shown to underestimate As concentrations in the well water relative to the local standard of 50 μg/L. 17 The fourth and main survey that this analysis relies on to document the effectiveness of different forms of As mitigation is a blanket survey of Araihazar upazila conducted in 2012− 2013 by a team of 10 local women coordinated by Columbia University and the University of Dhaka (Figure 3). Almost 49,000 wells serving a population of about 380,000 (2011 census) were tested with a different field kit. ...
... This proportion cannot be related to the 29% of high As wells reported by the BAMWSP survey in 2003 because of under-reporting of As concentrations by the field kit that was used. 17 The smaller HEALS subarea within Araihazar provides a better basis for comparing the proportion of wells with >50 μg/L As: 53% in 2000−2002 with 47% in 2012−2013. This modest decline is disappointing, although it should be pointed out that, whereas in 2000−2002 households were drinking from all wells because they could not have known their status with respect to As, only two-thirds of wells in the HEALS area perceived as unsafe were actually used for drinking or cooking in 2012−2013. ...
About 20 million rural Bangladeshis continue to drink well-water containing >50 ug/L arsenic (As). This analysis argues for re-prioritizing interventions on the basis of a survey of wells serving a population of 380,000 conducted one decade after a previous round of testing overseen by the government. The available data indicate that testing alone reduced the exposed population in the area in the short term by about 130,000 by identifying the subset of low As wells that could be shared at a total cost of <US$1 per person whose exposure was reduced. Testing also had a longer term impact as 60,000 exposed inhabitants lowered their exposure by installing new wells to tap intermediate (45-90 m) aquifers that are low in As at their own expense of US$30 per person whose exposure was reduced. In contrast, the installation of over 900 deep (>150 m) wells and a single piped-water supply system by the government reduced exposure of little more than 7,000 inhabitants at a cost of US$150 per person whose exposure was reduced. The findings make a strong case for long-term funding of free well testing on a massive scale with piped water or groundwater treatment only as a last resort.
... These field methods are less expensive and allow for rapid, on-site sample analysis and immediate feedback to the households. Field kits can be effective at discriminating As above and below the Bangladesh drinking water standard of 50 μg/L when performed by trained technicians, but do not provide continuous or discrete As concentrations, and often are subject to bias (George et al., 2012;Steinmaus et al., 2006;Van Geen et al., 2005). Improved analysis of test kit color changes could enable improved utilization of test results. ...
... A separate sample of 50 mL was also collected for field analysis done on site using the EconoQuick test kit (Industrial Test Systems Inc. http://www.sensafe.com/) according to the manufactures protocol and previous studies (George et al., 2012;Rahman et al., 2002;Steinmaus et al., 2006;Van Geen et al., 2005) with the addition of a photograph taken of the strip at the end of the test. ...
Arsenic (As) groundwater contamination is common yet spatially heterogeneous within most environments. It is therefore necessary to measure As concentrations to determine whether a water source is safe to drink. Measurement of As in the field involves using a test strip that changes color in the presence of As. These tests are relatively inexpensive, but results are subjective and provide binned categorical data rather than exact determinations of As concentration. The goal of this work was to determine if photos of field kit test strips taken on mobile phone cameras could be used to extract more precise, continuous As concentrations. As concentrations for 376 wells sampled from Araihazar, Bangladesh were analyzed using ICP-MS, field kit and the new mobile phone photo method. Results from the field and lab indicate that normalized RGB color data extracted from images were able to accurately predict As concentrations as measured by ICP-MS, achieving detection limits of 9.2μg/L, and 21.9μg/L for the lab and field respectively. Data analysis is most consistent in the laboratory, but can successfully be carried out offline following image analysis, or on the mobile phone using basic image analysis software. The accuracy of the field method was limited by variability in image saturation, and variation in the illumination spectrum (lighting) and camera response. This work indicates that mobile phone cameras can be used as an analytical tool for quantitative measures of As and could change how water samples are analyzed in the field more widely, and that modest improvements in the consistency of photographic image collection and processing could yield measurements that are both accurate and precise.
... The use of such field kits is particularly indicated where rapid on-site measurements are required and where the precision requirements are not tight and where there are logistical difficulties, including ensuring appropriate preservation, in transporting samples to fixed laboratories and returning data to the field. The reliability of such kits has been evaluated by van Geen et al. (2005) amongst others whilst Mukherjee et al. (2005) comments on human factors that may impact this. ...
... The detection of arsenic in the environment is important for maintaining public health. Arsenic analysis is performed using a combination of high-precision pretreatments, such as high-pressure liquid chromatography and highly sensitive analyzers [7,8]. While highprecision analytical techniques enable highly quantitative and qualitative analyses, they involve multiple steps in sample preparation and handling [9,10]. ...
Owing to its simplicity and sensitivity, electrochemical analysis is of high significance in the detection of pollutants and highly toxic substances in the environment. In electrochemical analysis, the sensitivity of the sensor and reliability of the obtained signal are especially dependent on the electrode characteristics. Electrodes with a high density of nanomaterials, which exhibit excellent activity, are useful as sensor substrates for pollutant detection. However, the effective placement of high-density nanomaterials requires a high degree of control over the particle size, particle shape, and distance between the particles on the substrate. In this study, we exploited the properties of boron-doped diamond (BDD) electrodes, which have a wide potential window, and succeeded in coating a highly dense layer of gold nanoparticles (AuNPs) at high potential. The AuNP-modified BDD (AuNP-BDD) electrodes comprising less than 100 nm AuNPs at a density of 125 particles/µm were electrochemically synthesized over a short period of 30–60 s. The AuNP-BDD electrodes were applied for detecting arsenic, which is one of the most abundant elements, and exhibited a limit of detection of 0.473 ppb in solution.
... There were accuracy and reliability problems in the results of testing samples by field kit was found and after many debates and experiments by researchers the use of these types of kits was stopped in West Bengal [14,17,18]. In the WHO report in 2003, it was also been said that they are in a position to support standard laboratory for arsenic testing but the debate on the field kit use continues [19]. ...
India and Bangladesh are the major countries affected by arsenic contamination in groundwater. These countries in collaboration with the various national and international organizations have installed Arsenic and Iron Removal Plants (AIRPs)Arsenic and Iron Removal Plants with different technologies to mitigate this problem. This study was conducted on four numbers of distinguished technologies installed in the North 24 Parganas district of West Bengal, India. This paper studied the performances of these AIRPs and statistical analysis is performed to compare among them. The Raw water arsenic concentration among the four AIRPs ranges between 22 and 400 µg/l and the Iron concentration lies between 510 and 4230 µg/l. Among the technologies, T1 seems to be the most efficient technology in removing arsenic with a mean of 98.25% overall arsenic removal efficiency with a standard deviationStandard deviation of 1.04%. The T3 technology seems another efficient technology with a mean overall removal efficiency of 91.46% but in the last few months a problem of backwashing affects the treated water quality and arsenic concentration found more than the acceptable limit as per WHO and BIS guideline. The other T2 and T4 technology were not so efficient in maintaining the arsenic and Iron level below the permissible limit constantly. There are plenty of operation and maintenance-related issue was found during the field visit and a critical review and percussion measurement also been made to improve the performance of the AIRPs.
... Takings the face value of field kit measurements increases the chance of incorrect and inconsistent labeling. That said, laboratory precision is not necessary when concentrations range across several orders of magnitude (van Geen et al., 2005). Health-based thresholds are often somewhat arbitrary. ...
Millions of people in Bangladesh drink well water contaminated with arsenic. Despite the severity of this heath crisis, little is known about the extent to which groundwater arsenic concentrations change over time: Are concentrations generally rising, or is arsenic being flushed out of aquifers? Are spatially patterns of high and low concentrations across wells homogenizing over time, or are these spatial gradients becoming more pronounced? To address these questions, we analyze a large set of arsenic concentrations that were sampled within a 25 km$^2$ area of Bangladesh over time. We compare two blanket survey collected in 2000/2001 and 2012/2013 from the same villages but relying on a largely different set of wells. The early set consists of 4574 accurate laboratory measurements, but the later set poses a challenge for analysis because it is composed of 8229 less accurate categorical measurements conducted in the field with a kit. We construct a Bayesian model that jointly calibrates the measurement errors, applies spatial smoothing, and describes the spatiotemporal dynamic with a diffusion-like process model. Our statistical analysis reveals that arsenic concentrations change over time and that their mean dropped from 110 to 96 $\mu$g/L over 12 years, although one quarter of individual wells are inferred to see an increase. The largest decreases occurred at the wells with locally high concentrations where the estimated Laplacian indicated that the arsenic surface was strongly concave. However, well with initially low concentrations were unlikely to be contaminated by nearby high concentration wells over a decade. We validate the model using a posterior predictive check on an external subset of laboratory measurements from the same 271 wells in the same study area available for 2000, 2014, and 2015.
... The Bangladesh Arsenic Mitigation and Water Supply Project has used the Hach EZ kit to test millions of wells. Prior studies evaluating the accuracy of this kit found it to be fairly accurate, correctly identifying the status of tested wells 88% of the time, provided the reaction time is increased from 20 to 40 min (van Geen, Cheng et al. 2005). ...
... The significant correlation between As and bicarbonate (Fig. 8a) may be due to the role of bicarbonate in As mobilization, since this anion can form mobile arseno-carbonate complexes (Kim et al., 2000(Kim et al., , 2003Bhattacharya et al., 2006). On the other hand, As and Fe are poorly correlated (Fig. 8b), suggesting (i) adsorption of As on Fe oxy-hydroxides (whether suspended or present as part of aquifer materials) (Voutsa et al., 1994;Pal et al., 2002;Peters et al., 2006) and/or (ii) formation of secondary solid phases not incorporating As from solution, such as siderite (FeCO 3 ) (Van Geen et al., 2005;Sracek et al., 2004., Biswas et al., 2012. ...
The geochemical composition of waters from wells fed by Taftan aquifer located east of Taftan volcano, mainly focusing on the distribution of arsenic, was investigated in order to provide insights into the geochemical processes controlling the chemistry of the shallow aquifer and the possible influence of hydrothermal fluids from the volcano on groundwater quality. For this purpose, 16 water samples were collected and analyzed for the determination of selected trace elements, major ions and stable isotopes (¹⁸O and ²H). The chemical and isotopic features of the investigated groundwater samples suggest that they are significantly affected by fluids originated from Taftan volcano driven toward the surface by local and regional fault systems. The volcanic source is also responsible for the relatively high concentrations of As, U and V, which pose severe concerns for the quality of the water resource in the area. Distribution of As seems to be independent of pH values and the concentrations of Fe, the latter commonly forming As-adsorbing minerals, likely due to the precipitation of siderite and the occurrence of As colloids. Lack of correlation between As and SO4 seems to exclude a significant As contribution from sulfide minerals.
... The collection containers were washed thrice with tube well water and then the sample was collected with five replications and stored. Same procedure of collection was followed by (Van Geen et al., 2005). Characterization of Groundwater Sample was carried out by performing the arsenic test, pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS) and turbidity. ...
Pakistan has limited freshwater resources which are depleting and deteriorating as well. Quality
of drinking water is also getting poorer day by day specially due to contamination of toxic heavy metals
and metalloid such as arsenic. Prolong and continuous consumption of arsenic even in minute quantity
can chain up with serious diseases. Safe limit of arsenic recommended by the World Health
Organization (WHO) is 0.01mg/L whereas arsenic contamination in study area ranges between 0.05 to
0.1 mg/L. Elimination of heavy metals like arsenic is very complicated to achieve. Adsorption is the
method which is not only efficient in removing heavy metals from water but economical also. Adsorbent
production from natural material or any trash material is attracting scientific community attention
because it is cost effective than the commercially available adsorbents. Cotton gin trash is a trash
material, which is produced while processing cotton. There is a crucial need to develop a method by
which this trash can be disposed-off systematically. This study has dealt with the disposal issue of cotton
gin trash and arsenic elimination by producing cotton gin trash activated carbon (AC-CGT). Through
this research, it was concluded that activated carbon can be produced from cotton gin trash by pyrolysis
process and it has a significant removable capacity of arsenic from groundwater. After adsorption
arsenic contamination became 0 mg/L. In this research, it was also observed that adsorption by ACCGT
has little impact on other parameters such as Turbidity, TDS, EC and pH.
... The method can falsely report H2S as As. Where H2S is uncommon, precautions against H2S may be dispensed with because avoidance itself can cause false positives from acetate contamination (van Geen et al. 2005a: these authors found 21 % of wells > 50 µg/L were misclassifiedsee van Geen et al. 2005b). ...
Arsenic pollution of groundwater, Pakistan
... Additionally, concurrent well WAs concentration for each mother and child was also obtained from this database. Laboratory analysis procedure for arsenic in drinking water has been described elsewhere (Cheng et al., 2004;Van Geen et al., 2005). Concurrent UAs concentration was measured by graphite furnace atomic absorption spectrophotometry (GFAA), using a Perkin-Elmer Analyst 800 system as described (Nixon et al., 1991). ...
Groundwater, the major source of drinking water in Bengal Delta Plain, is contaminated with geogenic arsenic (As)enrichment affecting millions of people. Children exposed to tubewell water containing As may be associated with thyroid dysfunction, which in turn may impact neurodevelopmental outcomes. However, data to support such relationship is sparse. The purpose of this study was to examine if chronic water As (WAs)from Holocene alluvial aquifers in this region was associated with serum thyroid hormone (TH)and if TH biomarkers were related to neurobehavioral (NB)performance in a group of adolescents. A sample of 32 healthy adolescents were randomly drawn from a child cohort in the Health Effects of Arsenic Longitudinal Study (HEALS)in Araihazar, Bangladesh. Half of these participants were consistently exposed to low WAs (<10 μg/L)and the remaining half had high WAs exposure (≥10 μg/L)since birth. Measurements included serum total triiodothyronine (tT 3 ), free thyroxine (fT 4 ), thyrotropin (TSH)and thyroperoxidase antibodies (TPOAb); concurrent WAs and urinary arsenic (UAs); and adolescents' NB performance. WAs and UAs were positively and significantly correlated with TPOAb but were not correlated with TSH, tT 3 and fT 4 . After accounting for covariates, both WAs and UAs demonstrated positive but non-significant relationships with TSH and TPOAb and negative but non-significant relationships with tT 3 and fT 4 . TPOAb was significantly associated with reduced NB performance indicated by positive associations with latencies in simple reaction time (b = 82.58; p < 0.001)and symbol digit (b = 276.85; p = 0.005)tests. TSH was significantly and negatively associated with match-to-sample correct count (b = −0.95; p = 0.05). Overall, we did not observe significant associations between arsenic exposure and TH biomarkers although the relationships were in the expected directions. We observed TH biomarkers to be related to reduced NB performance as hypothesized. Our study indicated a possible mechanism of As-induced neurotoxicity, which requires further investigations for confirmatory findings.
... Few samples were analysed in duplicates to ensure consistent results. Similar field tests have been adopted for the identification of tube wells contaminated with arsenic in order to avoid the water for domestic use (Van Geen et al., 2005;Jakariya et al., 2007). Such kits have also been suggested by health organisations for determining the water suitability to avoid water-borne diseases (WHO, 2006). ...
A water and soil quality baseline study was carried out across the ~ 4500 km² Vientiane Plain in Lao PDR. Eight water quality and nine soil parameters were analysed using field kits at 95 sites in March 2015. Elevated electrical conductivity and chloride were apparent at two sites due to geogenic leaching from the marine rock-salt present in some areas. Groundwater was acidic in most locations. Nitrate and faecal contamination were also observed from nitrogenous fertilizers (diffuse) and from leaky sewage pits (localised) respectively. Soil quality is neither nutrient deficient nor does it pose a threat to plant growth. Where groundwater is used for drinking, removal of bacterial contamination by simple filtration or boiling is sufficient. In the absence of a functional monitoring network in the Vientiane Plain, periodic surveys of this kind should be performed. The results should be made widely available to the relevant government departments and other stakeholders for better management of the land and water resources.
... Procedures for field sample collection and laboratory analyses are described elsewhere in detail (Cheng et al., 2004;Van Geen et al., 2005, 2007. Water samples were analyzed by high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) as previously described (Van Geen et al., 2007). ...
Drinking water arsenic (WAs) exposure has been linked toa number of detrimental health outcomes including anemia, primarily among pregnant women. Little is known about the effects of arsenic (As) on hematological disorders among men. We have examined the role of As exposure on hematological indicators of anemia in a group of men exposed to a wide range of As in their drinking water. We conducted a cross-sectional investigation among 119 healthy men in the Health Effects of As Longitudinal Study (HEALS) cohort, in rural Bangladesh. The participants are part of an ongoing study focused on evaluating the influence of As and smoking on immune function. Samples were collected at recruitment and analyzed for water As,urinary As (UAs) and UAs metabolites to assess As exposure. Blood samples were also collected at recruitment and assayed immediately for hematological parameters. We found that increased WAs levels were associated with decreased red blood cell counts [β=−0.13,pb0.0001] as well as hematocrit packed cell volumes [β=−0.68,p= 0.008] following adjustmentforage,smoking,bodymass index and polycyclic aromatic hydrocarbon-DNA adducts. Other measures of As exposure (UAs and its metabolites) demonstrated similar associations. Slightly stronger effects were observed among smokers. We also observed an effect of As on hemoglobin among smokers in relation to UAs [β=−0.54,pb0.05]. Our analysis revealed effects of As exposure on hematological indicators of anemia in a group of healthy male smokers and non-smokers
... The method can falsely report H2S as As. Where H2S is uncommon, precautions against H2S may be dispensed with because avoidance itself can cause false positives from acetate contamination (van Geen et al. 2005a: these authors found 21 % of wells > 50 µg/L were misclassifiedsee van Geen et al. 2005b). ...
Groundwater beneath the alluvial plain of the Indus River, Pakistan, is reported to be widely polluted by arsenic (As) and to adversely affect human health. In 79 groundwaters reported here from the lower Indus River plain, in southern Sindh Province, concentrations of As exceeded the WHO guideline value of 10 μg/L in 38%, with 22% exceeding 50 μg/L, Pakistan's guideline value. The As pollution is caused by microbially‐mediated reductive dissolution of sedimentary iron‐oxyhydroxides in anoxic groundwaters; oxic groundwaters contain < 10 μg/L of As. In the upper Indus River plain, in Punjab Province, localised As pollution of groundwater occurs by alkali desorption as a consequence of ion‐exchange in groundwater, possibly supplemented by the use for irrigation of groundwater that has suffered ion‐exchange in the aquifer and so has values > 0 for residual sodium carbonate.
In the field area in southern Sindh, concentrations of Mn in groundwater exceed 0.4 mg/L in 11% of groundwaters, with a maximum of 0.7 mg/L, as a result of reduction of sedimentary manganese oxides. Other trace elements pose little or no threat to human health. Salinities in groundwaters range from fresh to saline (EC up to 6 mS/cm). High salinities result from local inputs of waste‐water from unsewered sanitation, but mainly from evaporation/evapotranspiration of canal water and groundwater used for irrigation. The process does not concentrate As in the groundwater owing to sorption of As to soils. Ion‐exchange exerts a control on concentrations of Na, Ca, and B, but not on As. High values of Cl/Br mass ratios (most » 288, the marine value) reflect the pervasive influence on groundwater of sewage‐contaminated water from irrigation canals through seepage loss and deep percolation of irrigation water, with additional, well‐specific, contributions from unsewered sanitation.
... As a part of sustainable drinking water management, regular monitoring of As and Mn in all the handpumped tubewells in a region is necessary. For fast and low-cost determination and monitoring of As levels in tubewells, several field test kits have proven worthy for As screening by researchers such as van Geen et al. (2005) and Jakariya et al., (2007). Other applied test kits include Merck, Hach EZ, Quick arsenic, Wagtech Digital Arsenator (WFTK), and Chem-In Corp field test kit (CFTK) (Steinmaus et al., 2006;Sankararamakrishnan et al., 2008;Biswas et al., 2012a). ...
This study aimed to evaluate the potential of handpump tubewell platform color as a low-cost, quick and convenient screening tool for As and Mn in drinking water tubewells. For this study, groundwater samples and corresponding tubewell platform pictures were collected from 272 shallow tubewells in Matlab Upazila of South-Eastern Bangladesh. The result shows that arsenic concentration within the surveyed (n = 272) tubewells, 99% (n = 269) exceeded the World Health Organization (WHO) guideline value of 10 µg/L, and 98% (n = 267) exceeded the Bangladesh drinking water standards (BDWS) of 50 µg/L. In relation to the platform color concept, within 233 (total 272) red colored platform tubewells, 230 (99%) exceeded the WHO guideline value of 10 µg/L, and 229 (98%) tubewells exceeded BDWS of 50 µg/L. This result shows a strong correlation between the development of red color stain on tubewell platform and As concentrations in the corresponding tubewell water. This study suggests that red-colored platform can be used for primary identification of tubewells with an elevated level of As and thus could prioritize sustainable As mitigation management in developing countries where water comes from reductive shallow aquifers. This study did not confirm the potential for Mn screening, as red discoloration by Fe oxides was found to mask the black discoloration of Mn oxides. It is recommended to further investigate this screening tool in regions with a higher well-to-well variability of As contaminations, as in the presented study As was found >10ug/L in 99% of the tubewells.
... The potential benefits of laboratory-based analytical methods have been recognized for a long time, but studies have shown that they are not very efficient for on-site monitoring applications. With the technological advancement in the analytical chemistry, new techniques are developed through the introduction of advanced spectroscopy [30], model-based event detection [31], water quality sensors [32,33], microfluidics [34][35][36] and biosensors [37][38][39]. Recently, wireless sensor network has been adapted in various detection techniques for portability. ...
Water monitoring technologies are widely used for contaminants detection in wide variety of water ecology applications such as water treatment plant and water distribution system. A tremendous amount of research has been conducted over the past decades to develop robust and efficient techniques of contaminants detection with minimum operating cost and energy. Recent developments in spectroscopic techniques and biosensor approach have improved the detection sensitivities, quantitatively and qualitatively. The availability of in-situ measurements and multiple detection analyses has expanded the water monitoring applications in various advanced techniques including successful establishment in hand-held sensing devices which improves portability in real-time basis for the detection of contaminant, such as microorganisms, pesticides, heavy metal ions, inorganic and organic components. This paper intends to review the developments in water quality monitoring technologies for the detection of biological and chemical contaminants in accordance with instrumental limitations. Particularly, this review focuses on the most recently developed techniques for water contaminant detection applications. Several recommendations and prospective views on the developments in water quality assessments will also be included.
... These field test kits, like the Hach EZ or the ITS Econo-Quick performed rather well and reliably in the past to distinguish drinkable water based on both the 10 μg/l and the 50 μg/l threshold (George et. al, 2012, Geen et. al, 2005, Geen et. al, 2014. However, there are still several disadvantages of such field test kits. They are often unreliable around or below the WHO limit of 10 μg/l concentration, besides the human eye is not very sensitive to changes in the yellow color, not to mention that on the field reproducible lighting conditions, the first step of any ...
A portable colorimetric device is presented for arsenic ion detection in drinking water. The main purpose of this device – which was developed to complement a commercial water dearsenating station demanding regular (weekly to monthly) regeneration runs depending on its saturation – is to provide regular field measurements and easy, semi-automatic operation designed specifically for untrained, typically illiterate users e.g. the population of developing countries. The device exploits a commercially available, well established reagent kit, which is widely used in arsenic field-testing in many developing countries. The hereby presented custom-designed microfluidic system enhances the user-friendliness, the functionality and reliability of the test-strip based kit. The response for total inorganic arsenic ion concentrations (As(III) and As(V)) is linear in the 5–20 μg/l (ppb) range with a sensitivity of 1 μg/l, thus the device is capable to distinguish drinkable water based on the World Health Organization (WHO) guidelines of 10 μg/l. The average relative standard deviation of the measurements is 8% in the linear range and it is below 2% for higher arsenic concentrations (above 20 μg/l). The hardware construction of the device and the custom microfluidic system is presented in detail. The effect of elevated water sample temperature on the kinetics and performance of the device was also investigated in order to reduce the required time for the measurements. Stable and reliable arsenic concentration values were obtained after 60 min at 22 °C (ambient temperature) and after only 25 min at 50 °C water sample temperature, but at a cost of an increased relative standard deviation to 16%, in the linear range.
... At present only in India 62 million people are suffering from fluorosis, a crippling disease. The presence of uranium, boron, and manganese in groundwater of Bangladesh above WHO prescribed limiting values has already been reported (123,124). Unless immediate measures for detailed water analysis are undertaken and awareness among all the sections of society (with especially involving women) about contaminants in drinking water is generated, toxins of higher toxicity may affect in course of time. ...
Arsenic contamination in Groundwater beyond the regulatory limit of 0.05 mg/L is posing a
challenge to the water supply in the state of Bihar. The contamination is affecting the
shallow aquifer, within ~50 m bgl, which are the life line of hand pump based rural
drinking supply.
Elevated arsenic load, are confined in the flood plain, both in the active (flood prone) and
the older flood plain of the Ganga River. The Older Alluvium forming the Marginal Plain
Upland Surface (Singh 2004) in South Ganga Plain and Dissected Upland Interfulve
Surface in the North Ganga Plain have low arsenic load. In Bhojpur district maximum
arsenic concentration in Older Alluvium has been detected as 0.007mg/L. However,
localized high arsenic has also been detected in Darbhanga, Kishenganj far away from the
present course of the Ganga.
Arsenic distribution is marked with wide spatial variability resulting in patchyness in
distribution. No relation has been established between the concentration level of arsenic
and groundwater flow direction. Depth wise there is a significant reduction in concentration
beyond 40 m bgl. The aquifers at depth (> 80 m bgl), which appears to be of Pleistocene
age are contamination free even considering the WHO (1993) guidelines.
The drill-cut samples from the arsenic contaminated Holocene deposits are gray coloured
and rich in organic matter, indicating reducing environment. Deposition of organic matter
is facilitated by numerous cut-offs, abandoned channels and back-swamps which hold
water for a significant part of the post-monsoon period. Grain size distribution of sands
reveals a fluvio-lacustrine depositional environment during the Holocene period.
Chemically the groundwater is mildly acidic and fresh with TDS generally remaining within
800 mg/L. The anionic chemistry is dominated by HCO3- while the cationic chemistry is
marked by dominance of Ca2+ and Mg2+. Groundwater with high arsenic load is marked
with Ca-HCO3, Mg-HCO3 and Ca-Mg-HCO3 facies. PCA of the major chemical constituents
in Bhojpur district reveals high loadings of As (total), Ca2+ and Fe (total), and significant
HCO3- loadings in PC2. Release of As and Fe in aqueous phase is related to same
mobilization path, which is supported by positive correlation between them.
The arsenic contaminated Newer Alluvium belt exhibits flat topography with shallow water
levels (<10 m bgl) and sluggish groundwater movement. Long-term water level analyses of
Hydrograph Network Stations do not indicate any significant lowering of water level.
The main source of recharge of shallow aquifer is rainfall infiltration besides percolation
from surface water bodies. Tritium concentration also reveals young age of shallow
groundwater (<40 years). The abundance of organic carbon in the shallow alluvial
stratigraphy allows a part of it to be carried downward with the percolating groundwater.
The organic carbon stimulates microbial respiration and triggers reductive dissolution of As
and Fe in solid phase. This process also generates HCO3- and so produce the relationship
between AS and HCO3- in shallow groundwater
The deeper aquifers hold old water (> 3000 years) as indicated by 14C activity and appear to
have its recharge from far off places. Presence of sub-regional scale clay bed in Sone-Ganga
interfluve region in Bhojpur and Buxar districts inhibits direct vertical percolation of
arsenic contaminated water from shallow level to the deeper aquifer system beyond 120 m
bgl. In other affected areas of Middle Ganga Plain, the arsenic free deeper aquifers are of
good potential, where T remains > 5000 m2/day. Groundwater in these aquifers remains
under semi-confined to confined condition and can be developed for community scale water
supply through deep tube wells.
... As a part of sustainable drinking water management, regular monitoring of As and Mn in all the handpumped tubewells in a region is necessary. For fast and low-cost determination and monitoring of As levels in tubewells, several field test kits have proven worthy for As screening by researchers such as van Geen et al. (2005) and Jakariya et al., (2007). Other applied test kits include Merck, Hach EZ, Quick arsenic, Wagtech Digital Arsenator (WFTK), and Chem-In Corp field test kit (CFTK) (Steinmaus et al., 2006;Sankararamakrishnan et al., 2008;Biswas et al., 2012a). ...
... The Bangladesh Arsenic Mitigation and Water Supply Project has used the Hach EZ kit to test millions of wells. Prior studies evaluating the accuracy of this kit found it to be fairly accurate, correctly identifying the status of tested wells 88% of the time, provided the reaction time is increased from 20 to 40 min (van Geen, Cheng et al. 2005). ...
Background:
Millions of villagers in Bangladesh remain exposed to high levels of arsenic (As) from drinking untreated well-water even though the scale of the problem was recognized 15years ago. Water treatment at the household-level has been promoted as a viable complement but few longitudinal studies of their efficacy using an objective measure of exposure have been conducted. Participants (N=622) of a nutrition trial in Araihazar, Bangladesh were each provided with READ-F filters at the beginning of the study and encouraged to use them over the 6month duration of the intervention. Well-water As, treated water As, and urinary As were monitored periodically during the trial and measured again one year after the trial ended.
Results:
The READ-F filters were initially well received and median urinary As levels for participants declined from 117μg/L to 51μg/L within a single week. However, median urinary As levels gradually rose back to 126μg/L by the end of the trial. Fifty filters were replaced over the course of the trial because of insufficient As removal or reduced flow. With these exceptions, most of the treated water met the WHO guideline for As in drinking water of 10μg/L. One year after the nutritional trial ended, 95% of participants had abandoned their filter citing inconvenience as the primary reason. At that time, median urinary As levels for 10 participants who had switched to a nearby low-As well had declined to 63μg/L.
Conclusions:
Participants were probably no longer using the READ-F filter long before the 6month nutritional intervention ended despite claiming that they were using them. Household-level treatment is likely to continue to play a minor role in the effort to reduce As exposure in Bangladesh. Understanding the limitations of such expensive interventions is important for future policy regarding As mitigation.
... We were unable to systematically obtain information about well use at follow-up and therefore relied on biomarkers of exposure. Field sample collection and laboratory analysis procedures are described elsewhere in detail (Cheng et al. 2004;van Geen et al. 2003van Geen et al. , 2005. ...
Background:
Arsenic (As) exposure from drinking water is associated with modest intellectual deficits in childhood. It is not known whether reducing exposure is associated with improved intelligence.
Objective:
To determine whether reducing As exposure is associated with improved child intellectual outcomes.
Methods:
Three hundred and three 10-year-old children drinking from household wells with a wide range of As concentrations were enrolled at baseline. In the subsequent year, deep community wells, low in As, were installed in villages of children whose original wells had high water As (WAs ≥50 µg/L). For 296 children, WISC-IV intelligence, using a version modified for the study population, was assessed at baseline and approximately two years later; analyses considered standardized scores for both Full Scale IQ and Verbal Comprehension, Perceptual Reasoning, Working Memory, Processing Speed Indices. Creatinine-adjusted urinary arsenic (UAs/Cr), blood As (BAs) and blood manganese (BMn) were assessed at both times.
Results:
UAs/Cr concentrations declined significantly by follow-up for both the High and Low (< 50 µg/L) WAs subgroups. At baseline, adjusting for maternal age and intelligence, plasma ferritin, head circumference, home environment quality, school grade and BMn, UAs/Cr was significantly negatively associated with Full Scale IQ, and with all Index scores (except Processing Speed). After adjusting for baseline Working Memory scores and school grade, each 100-µg/g reduction in UAs/Cr from baseline to follow-up was associated with a 0.91 point increase in Working Memory (95% CI: 0.14, 1.67). The change in UAs/Cr across follow-up was not significantly associated with changes in Full Scale IQ or Index scores.
Conclusions:
Installation of deep, low As, community wells lowered UAs, BAs and BMn. A greater decrease in UAs/Cr was associated with greater improvements in Working Memory scores, but not with a greater improvement in Full Scale IQ.
... However, as observed in several studies (e.g. van Geen et al., 2005;Nath et al., 2009), the lack of correlation may be limited by the occurrence of multiple geochemical processes occurring simultaneously in the aquifer. The lack of correlation between As and Fe can further be explained if dissolved Fe does not remain in solution then there should be a formation of secondary solid phases such as siderite (FeCO 3 ) that do not incorporate As from solution . ...
... There is 90-100 % applicability of field test kit for the arsenic concentration below 0.05 ppm and 88 % for the range between 0.05 to 0.l0 ppm and 87 % in the range of 0.1-0.5 ppm. Van Geen et al. (2005) studied comparison of field and laboratory measurements of arsenic in groundwater of Araihazar, Bangladesh indicates that the most widely used field kit correctly determined the status of 88 % of 799 wells relative to the local standard of 50 μg/L As. Additional tests show that the inconsistencies, mainly underestimates in the 50-100 μg/L As range, can be avoided by increasing the reaction time from 20 to 40 min. ...
In southern Punjab, arsenic (As) contents in groundwater is one of the major problems. A preliminary study was conducted to evaluate the extent of As concentration along with pH, electrical conductivity (EC), total dissolved salts (TDS), and heavy metals Cu, Ni, Cd, Fe, and Mn in 121 groundwater samples of the study area. The range values of As were below detection limit (BDL) to 100 ppb, pH (6.4–7.9), EC (0.503–40.8 mS/cm), Cu (BDL—1142 μg/L), Ni (BDL—179.2 μg/L), Fe (1.1–995.4 μg/L), and Mn (0.2–499.2 μg/L) in groundwater. The As concentration in 33.9 % samples was higher than prescribed limit (10 ppb) of WHO for drinking water while TDS in 70.3 %, Cu in 14 %, Ni in 5.7 %, Fe of 15.7 %, and Mn in 28.92 % were observed higher than their respective permissible limits. The correlation coefficient (r) was carried out for seven parameters, indicating positive correlation of As with Fe (0.27). Contamination index (C
d) of 44.9 % ground water was observed >3 indicating the extent of contamination. The present study indicated the water samples collected from riverine area had higher concentration of As than the samples from canal irrigated or in vicinity of the desert area.
... Total As concentration was analyzed by high-resolution inductively-coupled plasma mass spectrometry (HR ICPMS), with a detection limit of <0.2 μg/L. The long-term reproducibility determined from consistency standards included with each run is relatively stable over time [20][21][22]. Baseline well water As data were available for 100% of participants. ...
... These analyses require expensive equipment at central laboratories. For example, arsenic in water systems is commonly detected by atomic absorption spectrophotometry [11], while fluoride is typically detected using a potentiometric ion-selective electrode method or ion chromatography [12]. These analyses are off-line and require sample collection which can be a problem in developing countries if the sampling location is in a remote area. ...
The provision of safe water and adequate sanitation in developing countries is a must. A range of chemical and biological methods are currently used to ensure the safety of water for consumption. These methods however suffer from high costs, complexity of use and inability to function onsite and in real time. The microbial fuel cell (MFC) technology has great potential for the rapid and simple testing of the quality of water sources. MFCs have the advantages of high simplicity and possibility for onsite and real time monitoring. Depending on the choice of manufacturing materials, this technology can also be highly cost effective. This review covers the state-of-the-art research on MFC sensors for water quality monitoring, and explores enabling factors for their use in developing countries.
... However, as observed in several studies (e.g. van Geen et al., 2005;Nath et al., 2009), the lack of correlation may be limited by the occurrence of multiple geochemical processes occurring simultaneously in the aquifer. The lack of correlation between As and Fe can further be explained if dissolved Fe does not remain in solution then there should be a formation of secondary solid phases such as siderite (FeCO 3 ) that do not incorporate As from solution . ...
Study region: Arsenic enriched groundwater regime within low-industrialized Brahmaputra floodplains in Assam, NE India.
Study focus: We examined the origin, distribution and processes of As release by investigating the salient groundwater chemistry and subsurface sedimentological characteristics. Besides collection of groundwater samples from domestic and public water supply wells, sediment samples from boreholes were investigated for textural and colour linkages.
New hydrological insights for the region: Arsenic concentrations above the WHO guideline value of 10 μg/L were present in 33 wells and above the previous Indian national drinking standard of 50 μg/L were present in 15 wells. The green-olive colour sediments were more likely to yield As-enriched groundwater. The supersaturation of groundwater with respect to Fe(II) minerals, such as siderite and vivianite, explained the poor correlation between dissolved As and Fe. The result reinforced the phenomenon of reductive dissolution of Fe(III) oxyhydroxides releasing As to groundwater. This study throws light on the processes and mechanisms involved with As release in groundwater. The homogenous floodplain terrain makes the hydrological As imprint unambiguous and the hydrogeological signatures untarnished. Considering the absence of anthropogenic sources in the study area, the conclusions on the nature and causes for As release to groundwater looked dependable although the final contamination at specific subsurface sites would be influenced by advection–dispersion of groundwater flow accompanied by retardation, ion exchange, surface complexation and possible biodegradation.
... If water samples were found to have arsenic concentrations at or below the detection limit of GFAA, they were then analyzed by high-resolution inductively-coupled plasma mass spectrometry (HR ICPMS), with a detection limit of < 0.1 µg/L (Chen et al. 2007b). The long-term reproducibility determined from consistency standards included with each run is relatively stable over time (Cheng et al. 2004;Cheng et al. 2005;Van Geen et al. 2005). ...
Background: Cross-sectional studies have shown associations between arsenic exposure and prevalence of high BP; however, studies examining the relationship of arsenic exposure with longitudinal changes in blood pressure are lacking.
Method: We evaluated associations of arsenic exposure in relation to longitudinal change in
blood pressure in 10,853 participants in the Health Effects of Arsenic Longitudinal Study
(HEALS). Arsenic was measured in well water and in urine samples at baseline and in urine samples every two years after baseline. Mixed effect models were used to estimate the association of baseline well and urinary creatinine-adjusted arsenic with blood pressure annual change during follow-up (median, 6.7 years).
Result: In the HEALS population, the median water arsenic concentration at baseline was 62 µg/L. Individuals in the highest quartile of baseline water arsenic or urinary creatinine-adjusted arsenic had a greater annual increase in SBP compared with those in the reference group (β=0.48 mmHg/year; 95% CI: 0.35-0.61, and β=0.43 mmHg/year; 95% CI: 0.29-0.56) for water arsenic and urinary creatinine-adjusted arsenic, respectively) in fully adjusted models. Likewise, individuals in the highest quartile of baseline arsenic exposure had a greater annual increase in DBP (β=0.39 mmHg/year; 95% CI: 0.30, 0.49, and β=0.45 mmHg/year; 95% CI: 0.36, 0.55) for water arsenic and urinary creatinine-adjusted arsenic, respectively) compared with those in the lowest quartile.
Conclusion: Our findings suggest that long-term arsenic exposure may accelerate age-related increases in blood pressure. These findings may help explain associations between arsenic exposure and cardiovascular disease.
... Field sample collection and laboratory analytical procedures are described elsewhere in detail [48,49]. Water samples were collected in 20-mL polyethylene scintillation vials. ...
Kidney disease is emerging as an arsenic (As)-linked disease outcome, however further evidence of this association is warranted. Our first objective for this paper was to examine the potential renal toxicity of As exposure in Bangladesh. Our second objective relates to examining whether the previously reported positive association between urinary creatinine (uCrn) and As methylation may be explained by renal function. We had hypothesized that these associations relate to supply and demand for s-adenosylmethionine, the methyl donor for both creatine synthesis and As methylation. Alternatively, renal function could influence both As and creatinine excretion, or the As metabolites may influence renal function, which in turn influences uCrn. We conducted a cross-sectional study (N = 478) of adults, composed of a sample recruited in 2001 and a sample recruited in 2003. We assessed renal function using plasma cystatin C, and calculated the estimated glomerular filtration rate (eGFR). Consistent with renal toxicity of As, log-uAs had a marginal inverse association with eGFR in the 2003 sample (b = -5.6, p = 0.07), however this association was not significant in the 2001 sample (b = -1.9, p = 0.24). Adjustment for eGFR did not alter the associations between uCrn and the %uAs metabolites, indicating that GFR does not explain these associations. Increased eGFR was associated with increased odds of having %uInAs >12.2% (2001: OR = 1.01, 95%CI (1.00,1.03); 2003: OR = 1.04, 95%CI (1.01,1.07)). In the 2003 sample only, there was a negative association between eGFR and %uDMA (b = -0.08, p = 0.02). These results may indicate differential effects of renal function on excretion of InAs and DMA. Alternatively, a certain methylation pattern, involving decreased %InAs and increased %DMA, may reduce renal function. Given that these studies were cross-sectional, we cannot distinguish between these two possibilities. Discrepancies between the samples may be due to the higher As exposure, poorer nutrition, and lower As methylation capacity in the 2003 sample.
In this report, we describe a practical method for the colorimetric determination of dissolved inorganic arsenic content in water samples, using a silver coordination polymer as the sensing material. We demonstrate that a crystalline polymer framework can be used to stabilize silver(I) ions, greatly reducing both photosensitivity and water solubility, while still affording sufficient reactivity to detect arsenic in water samples at low parts-per-billion (ppb) levels. Test strips fabricated with the silver-based polymer are shown to be effective for field tests of groundwater under real-world operating conditions and display performance that is competitive with commercially available mercury-based test strips. Spectroscopic methods are also used to probe the reaction products formed, in order to better understand the sensing mechanism. Thus, our work provides the foundation for an improved field test that could be deployed to help manage groundwater usage in regions where arsenic contamination is problematic but sophisticated lab testing is not readily available.
A complex of reduced graphene oxide (rGO) and fluorescein (FL) dye nanoparticles of size between 50 and 100 nm has been prepared and its sensing performance for detection of As(III) in drinking water has been reported. When As(III) binds to the rGO–FL nanoparticles the relative quenching of fluorescence was increased with increase in As(III) concentration thus provide two linear calibration ranges (0–4.0 mmol L⁻¹ and 4.0–10 mmol L⁻¹). The fluorescence quenching mechanism was investigated by using time-resolved fluorescence spectroscopy and molecular modeling. The detection limit of this sensor has been determined as equal to 0.96 µg L⁻¹ which is about 10 times lower than the WHO stipulated standard for As(III) in drinking water (10 µg L⁻¹). The analytical performance and potential application of the nanosensor was compared to commercial field kits used in arsenic monitoring. The sensor proposed in this study is fast, sensitive and accurate for detection of As(III) in drinking water and environmental samples.
Today, various methods such as bioleaching are increasingly used to remove toxic and reuse useful metals from low-grade ores and tailings. Bioleaching is an ecologically based technique carried by iron or sulfur-oxidizing bacteria, which convert insoluble metal sulfide to soluble metal sulfate. The purpose of this study was to test and compare two different methods, including Flask and Column experiments, to remove Zinc, Copper, Arsenic, and Iron. The materials were the same in both tests; inoculum came from the tailings of Neves-Corvo Mine, and the mineral sample was collected from Panasqueira Wolfram-Tin mine. Firstly, the cultures were tested for metal resistance and adapted by 3-day transference, adding sodium thiosulfate as an energy source supplement. Secondly, bioleaching tests were conducted in Flasks and Columns in 35 and 30 days, respectively. Finally, samples were taken to evaluate particle size, chemical compositions, bacterial growth, pH, oxidation–reduction potential (ORP), sulfate concentration, and metal content in the leachate. Besides, the Scanning Electron Microscope (SEM) pictures proved the existence of bacterial cells during the bioleaching tests. The results indicated that the Flask tests were superior to Column experiments in removing Zinc, Arsenic, and Copper from the mineral ore samples. However, Column experiments showed better results in the recovery of Iron in comparison with Flask tests.
Field kits for testing the level of a toxicant in the environment are inherently less accurate than a laboratory instrument. Using a specific example, we argue here that kit measurements still have a key role to play when the spatial distribution of a toxicant is very heterogeneous. The context is provided by the groundwater arsenic problem in Bangladesh. We combine here two data sets, a blanket survey of 6595 wells over a 25 km2 based on laboratory measurements and 900 paired kit and laboratory measurements from the same area. We explore different hypothetical mitigation scenarios based on actual data that rely on households with a high-arsenic well switching to a nearby low-arsenic well. We show that the decline in average exposure to arsenic from relying on kit rather than laboratory data is modest in relation to the logistical and financial challenge of delivering exclusively laboratory data. Our analysis indicates that the 50 g/L threshold used in Bangladesh to distinguish safe and unsafe wells, rather than the WHO guideline of 10 g/L, is close to optimal in terms of average exposure reduction. We also show, however, that providing kit data at the maximum possible resolution rather than merely classifying wells as unsafe or safe would be even better. These findings are relevant as the government of Bangladesh is about to launch a new blanket testing campaign of millions of wells using field kits.
Despite the increased interest and great progress obtained on arsenic test, it is still a challenge to accomplish the on-site determination of arsenic in rice due to the expensive instrumentation and harsh digestion process. In this work, MnFe2O4 micromotors were found to retain high catalytic activity to simultaneously produce large amounts of hydroxyl radicals and O2 bubbles in the presence of H2O2. Interestingly, the generated bubbles autonomously propel the micromotors and prevent them from depositing, thus keeping their high catalytic activity. As a result, an MnFe2O4 micromotors enhanced digestion method was developed for the field digestion of rice samples within 100 min only using H2O2, which was further utilized to realize the on-site detection of arsenic in rice by coupling with the Gutzeit method followed headspace solid phase extraction. A quantification limit of 40 μg kg⁻¹ was obtained for the determination of arsenic in rice. Owing to their capabilities of the efficient and rapid adsorption of arsenic and continuous movement, a MnFe2O4 micromotors enhanced solid phase extraction was also established for the sensitive determination of arsenic in water with a 1 μg L⁻¹ of quantification limit. The accuracy of the developed method was validated via analysis of a Certified Reference Material of rice (GBW10043) and a series of rice and water samples with satisfactory results, showing promising potential in the sensitive on-site detection of arsenic in rice and water samples.
Arsenic (As) contamination of groundwater is a serious threat to human health. Apart from anthropogenic sources, favorable geological conditions also result in elevation of the arsenic problem in Asia, especially in South East Asia. More than 100 million people in South East Asian countries especially Bangladesh, West Bengal (India), Vietnam, China, drink and cook with arsenic-contaminated water, which causes chronic health problems for a long time. A large number of mechanism for removing As from drinking water includes the use of filters, which differ in their efficiency and applicability. In the present study, we propose the use of biofilters prepared from lichen biowaste for removal of arsenic from contaminated water. Six lichen species were tested for the applicability as biofilters. The physicochemical analysis confirmed the presence of high elemental (C, N, H, O) content in the treated lichen species. It was observed that species having high elemental content were able to remove arsenic more effectively.
Background:
Exposure to inorganic arsenic (As) from drinking water is associated with modest deficits in intellectual function in young children; it is unclear whether deficits occur during adolescence, when key brain functions are more fully developed.
Objectives:
We sought to determine the degree to which As exposure is associated with adolescent intelligence, and the contributory roles of lead, cadmium, manganese and selenium.
Methods:
We recruited a cross-section of 726 14-16 year olds (mean age = 14.8 years) whose mothers are participants in the Bangladesh Health Effects of Arsenic Longitudinal Study (HEALS), and whose household well water As levels, which varied widely, were well characterized. Using a culturally modified version of the WISC-IV, we examined raw Full Scale scores, and Verbal Comprehension, Perceptual Reasoning, Working Memory and Processing Speed Indices. Blood levels of As (BAs), Mn, Pb, Cd and Se were assessed at the time of the visit, as was creatinine-adjusted urinary As (UAs/Cr).
Results:
Linear regression analyses revealed that BAs was significantly negatively associated with all WISC-IV scores except for Perceptual Reasoning. With UAs/Cr as the exposure variable, we observed significantly negative associations for all WISC-IV scores. Except for Se, blood levels of other metals, were also associated with lower WISC-IV scores. Controlling for covariates, doubling BAs, or UAs/Cr, was associated with a mean decrement (95% CI) of 3.3 (1.1, 5.5), or 3.0 (1.2, 4.5) points, respectively, in raw Full scale scores with a sample mean of 177.6 (SD = 36.8). Confirmatory analyses using Bayesian Kernel Machine Regression, which identifies important mixture members, supported these findings; the primary contributor of the mixture was BAs, followed by BCd.
Conclusions:
Our data indicate that the adverse consequences of As exposure on neurodevelopment observed in other cross-sectional studies of younger children are also apparent during adolescence. They also implicate Cd as a neurotoxic element that deserves more attention.
Background:
Inorganic arsenic (As) is methylated via one carbon metabolism (OCM) to mono- and dimethylated arsenicals (MMA and DMA), facilitating urinary excretion. Hyperhomocysteinemia (HHcys), a marker of impaired OCM, is a risk factor for As-induced skin lesions, but the influences of single nucleotide polymorphisms (SNPs) in OCM genes on Hcys, As metabolism and skin lesion risk is unclear.
Objectives:
To (i) explore genetic sources of Hcys and the causal role of HHcys in As-induced skin lesion development using OCM genetic proxies for HHcys and (ii) identify OCM SNPs associated with urinary As metabolite proportions and/or skin lesion incidence.
Methods:
We conducted a case-control study nested in the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh which 876 incident skin lesion cases were matched to controls on sex, age, and follow-up time. We measured serum Hcys, urinary As metabolites, and 26 SNPs in 13 OCM genes.
Results:
Serum Hcys and urinary %DMA were independently associated with increased and decreased odds of skin lesions, respectively. The T allele of MTHFR 677 C ➔ T (rs1801133) was associated with HHcys, higher %MMA, and lower %DMA, but not with skin lesions. Interactions between SNPs and water As on skin lesion risk were suggestive for three variants: the G allele of MTRR rs1801394 and T allele of FOLR1 rs1540087 were associated with lower odds of skin lesions with lower As (≤50 μg/L), and the T allele of TYMS rs1001761 was associated with higher odds of skin lesions with higher As.
Conclusions:
While HHcys and decreased %DMA were associated with increased risk for skin lesions, and MTHFR 677 C ➔ T was a strong predictor of HHcys, MTHFR 677 C ➔ T was not associated with skin lesion risk. Future studies should explore (i) non-OCM and non-genetic determinants of Hcys and (ii) if genetic findings are replicated in other As-exposed populations, mechanisms by which OCM SNPs may influence the dose-dependent effects of As on skin lesion risk.
Since 1980s, elevated concentrations of As in groundwater across southern Asia have been a serious problem for over 100 million villagers relying on inexpensive shallow tubewells. The level of exposure has caused widespread illness including various cancers. Despite the magnitude of the health threat and a decade of research by numerous teams, many of the most basic factors and processes controlling arsenic within deltaic and floodplain aquifer systems remain unresolved. Particular scientific issues are, (i) ultimate source of As, (ii) physico-chemical factors controlling spatial/temporal variations of As, (iii) impact of anthropogenic activities, and so on. The aim of this review is to make clear the controversial issues in this field, and to suggest what issues are needed to clarify in near future. This review is classified into 4 chapters. Geochemical characteristics of As contaminated groundwater in Bengal Basin are firstly overviewed. In the second chapter, experimental studies related to the low temperature geochemistry of As are summarized, e.g., molecular structure analysis, speciation, and water-rock interaction. In the third chapter, previously proposed hypotheses for mechanism of groundwater As contamination are outlined. Considering the background studies, current controversial issues and future prospect are proposed in the final chapter.
Drinking water arsenic (WAs) exposure has been linked to a number of detrimental health outcomes including anemia, primarily among pregnant women. Little is known about the effects of arsenic (As) on hematological disorders among men. We have examined the role of As exposure on hematological indicators of anemia in a group of men exposed to a wide range of As in their drinking water. We conducted a cross-sectional investigation among 119 healthy men in the Health Effects of As Longitudinal Study (HEALS) cohort, in rural Bangladesh. The participants are part of an ongoing study focused on evaluating the influence of As and smoking on immune function. Samples were collected at recruitment and analyzed for water As, urinary As (UAs) and UAs metabolites to assess As exposure. Blood samples were also collected at recruitment and assayed immediately for hematological parameters. We found that increased WAs were associated with decreased red blood cell counts [β=-0.13, p<0.0001] as well as hematocrit packed cell volume [β=-0.68, p=0.008] following adjustment for age, smoking, body mass index and polycyclic aromatic hydrocarbon-DNA adducts. Other measures of As exposure (UAs and its metabolites) demonstrated similar associations. Slightly stronger effects were observed among smokers. We also observed an effect of As on hemoglobin among smokers in relation to urinary As [β=-0.54, p<0.05]. Our analysis revealed effects of As exposure on hematological indicators of anemia in a group of healthy male smokers and non-smokers.
This study considers potential policy responses to the still very high levels of exposure to arsenic (As) caused by drinking water from shallow tubewells in rural Bangladesh. It examines a survey of 4,109 households in 76 villages of Araihazar upazila conducted two years after a national testing campaign swept through the area. The area is adjacent to the region where a long-term study was initiated in 2000 and where households are periodically reminded of health risks associated with well-water elevated in As. Results confirm that testing spurs switching away from unsafe wells, although the 27% fraction who switched was only about half of that in the long-term study area. By village, the fraction of households that switched varied with the availability of safe wells and the distance from the long-term study area. Lacking follow-up testing, two years only after the campaign 21% of households did not know the status of their well and 21% of households with an unsafe well that switched did so to an untested well. Well testing is again urgently needed in Bangladesh and should be paired with better ways to raise awareness and the installation of additional deep community wells.
A multidisciplinary approach to research affords the opportunity of objectivity, creation of new knowledge and potentially a more generally acceptable solution to problems that informed the research in the first place. It increasingly features in national programmes supporting basic and applied research, but for over 40 years, has been the arena for many research teams in environmental geochemistry and health. This study explores the nature of multidisciplinary research in the earth and health sciences using a sample selected from co-authored articles reporting research on arsenic (As) in drinking water from 1979 to 2013. A total of 889 relevant articles were sourced using the online version of the science citation index—expanded (SCI-expanded). The articles were classified according to author affiliation and later by author discipline/research interests using the Revised Field of Science and Technology Frascati manual DSTI/EAS/STP/NESTI (2006) 19/FINAL and a decision algorithm. Few articles were published on the topic until 2000. More articles were published across all affiliations in the last 10 years of the review period (2004–2013) than in the first 10 years (1979–1988). Only 84 (~9%) articles fell within the “earth and health” only and “earth, health and other” categories when classification was undertaken by author affiliation alone. This suggests that level of collaboration between earth and health scientists in arsenic in drinking water research may be very low. By refining the classification further using author discipline/research interests, only 28 of the 84 articles appear to be co-authored by earth and health scientists alongside professionals in other fields. More than half of these 28 articles involved descriptive non-experimental, observational study designs, limited in direct causal hypotheses and mechanistic investigation. If collaborative research is to lead to the increased multidisciplinary research, early interaction should be encouraged between students from different disciplines. In order to achieve multidisciplinarity in practise, it is imperative that scientific communities and research agencies do more to encourage interaction and integration between researchers from different disciplines. This must develop from educational institutions seeing opportunities to improve graduate skills in an increasingly diverse research landscape.
Arsenic exposure is a global health hazard, particularly in areas with industrial wastewater runoff and high levels of naturally occurring arsenic-bearing soil. Current water filtration devices lack portability, severely limiting their use for wide-scale public health. In the present study, bone char, hydroxyapatite, and goethite were incorporated into electrospun polystyrene scaffolds to evaluate their arsenic binding or adsorption properties in a cost-effective, stable device with the potential for portability. Feasibility of incorporation for all dopants in the study was demonstrated using electron microscopy. Arsenic testing on contaminated water with either dopant alone or dopant-incorporated electrospun scaffolds demonstrated that the dopant-incorporated electrospun scaffolds increased arsenic binding over control, with a trend of increased arsenic binding over the dopant only counterparts. The results indicate that the low-cost, easily fabricated electrospun polystyrene is a prime choice for creating filter materials impregnated with metal binding or adsorbing materials for use in water filtration devices.
The presence of toxic levels of inorganic arsenic in drinking water is a worldwide problem. Measurement of millions of samples in the field for arsenic is an analytical challenge and the first step to solve the problem. Here, we developed a novel electrochemical arsine sensor and system based on the cell: C(s)/I3-I2, AsH3(g/aq)//I3-, I2 AgI(s)/Ag(s), where I3-/I2 mediated AsH3(g/l) oxidation which occurred on the C(s) electrode. The sensor system requires 50 μL of 10 mM iodine solution and a small piece of filter paper placed inside a novel electrochemical cell. The cell exhibited highly efficient arsine mass transport with a limit of detection of 15 μg/L As(III) in water. A mathematical model of mass transfer of AsH3(g/aq) and following electrochemical reaction was developed and applied to explain the experimental data. Groundwater samples containing arsenic were measured to prove its utility in a field deployable instrument.
A quartz crystal microbalance sensor has been developed for the determination of inorganic arsenic species in water. The gold electrode surface was modified by a self-assembled layer of dithiothreitol, and the frequency change of the modified crystal was proportional to the arsenic concentration from 0 to around 50 μg L−1, a range which spans the current US EPA maximum contaminent level of 10 μg L−1 in drinking water. As dithiothreitol is capable of reducing arsenate to arsenite, the sensor detects both species. The method was applied to the determination of arsenic in spiked rain, tap, pond and bottled water; recoveries not significantly different from 100% were obtained for a number of spike additions of less than 10 μg L−1. Arsenic was only detected in the bottled water sample, at a concentration of 8 μg L−1. This method is simple, fast, and inexpensive compared with other conventional arsenic detection methods, and has the potential to be used in the field.
The arsenic-affected areas of West Bengal are lying on a sediment of Younger Deltaic Deposition (YDD). The same sediment extends eastwards towards Bangladesh, covering the approximate area of 34 districts out of a total of 64 districts in Bangladesh. We suspect that the groundwater of these 34 districts of Bangladesh may be arsenic-contaminated. So far, we have collected 3106 water samples for analysis from 28 out of these 34 districts and in 27 districts 38% of the water samples we had analysed contain arsenic above 0.05 mg/l. Area and population of these 27 districts are 51,000 km2 and 36 million respectively. Out of these 27 districts, so far, we have surveyed 20 districts for arsenic patients, and in 18 districts we have identified people having arsenical skin lesions such as melanosis, leucomelanosis, keratosis, hyperkeratosis, dorsum, non-petting oedema, gangrene and skin cancer. During our preliminary field survey in 45 arsenic-affected villages in 18 districts, from a random examination of 1630 people, including children, 57.5% have arsenical skin-lesions. While comparing the West Bengal arsenic scenario with the available data of Bangladesh, it appears that Bangladesh's arsenic calamity may be more severe. If our prediction that the groundwater of Bangladesh's 34 district is likely to be arsenic-contaminated comes true, then more than 50 million people would be at risk. To combat the situation, Bangladesh needs a proper utilization of its vast surface and rain water resources. Proper watershed management is required urgently.
Our present study with respect to arsenic in water from different environment of aquatic systems considering both surface and sub-surface geological condition with an emphasis to surface erosion and deposition of soil sediment in the Bangladesh Flood Plain and Deltaic Region reflects some clue for possibility of huge arsenic free reservoir water.
To monitor the effectiveness of deep community wells in reducing exposure to elevated levels of arsenic in groundwater pumped from shallower aquifers.
Six community wells ranging in depth from 60 m to 140 m were installed in villages where very few of the wells already present produced safe water. By means of flow meters and interviews with villagers carrying water from the community wells, a study was made of the extent to which these were used during one year. The results were compared with household and well data obtained during a previous survey in the same area.
The mean arsenic concentration in water pumped from wells already in use in the villages where the community wells, were installed was 180 +/- 140 micrograms/l (n = 956). Monthly sampling for 4-11 months showed that arsenic levels in groundwater from five of the six newly installed wells were consistently within the WHO guideline value of 10 micrograms/l for drinking-water. One of these wells met the Bangladesh standard of 50 micrograms/l arsenic but failed to meet the WHO guideline values for manganese and uranium in drinking-water. The community wells were very popular. Many women walked hundreds of metres each day to fetch water from them. On average, 2200 litres were hand-pumped daily from each community well, regardless of the season.
A single community well can meet the needs of some 500 people residing within a radius of 150 m of it in a densely populated village. Properly monitored community wells should become more prominent in campaigns to reduce arsenic exposure in Bangladesh. Between 8000 and 10,000 deep community wells are needed to provide safe water for the four to five million people living in the most severely affected parts of the country.
A rapid and sensitive method was developed to determine, with a single dilution, the concentration of 33 major and trace elements (Na, Mg, Si, K, Ca, Li, Al, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, In, Sn, Sb, Cs, Ba, Re, Hg, Pb, Bi, U) in groundwater. The method relies on high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) and works across nine orders of magnitude of concentrations. For most elements, detection limits for this method are considerably lower than methods based on quadrupole ICP-MS. Precision was within or close to +/-3% (1 sigma) for all elements analyzed, with the exception of Se (+/-10%) and Al (+/-6%). The usefulness of the method is demonstrated with a set of 629 groundwater samples collected from tube wells in Bangladesh (Northeast Araiharzar). The results show that a majority of tube well samples in this area exceed the WHO guideline for As of 10 microg L(-1), and that those As-safe wells frequently do not meet the guideline for Mn of 500 microg L(-1) and U of 2 microg L(-1).
Exposure to arsenic has long been known to have neurologic consequences in adults, but to date there are no well-controlled studies in children. We report results of a cross-sectional investigation of intellectual function in 201 children 10 years of age whose parents participate in our ongoing prospective cohort study examining health effects of As exposure in 12,000 residents of Araihazar, Bangladesh. Water As and manganese concentrations of tube wells at each child's home were obtained by surveying all wells in the study region. Children and mothers came to our field clinic, where children received a medical examination in which weight, height, and head circumference were measured. Children's intellectual function on tests drawn from the Wechsler Intelligence Scale for Children, version III, was assessed by summing weighted items across domains to create Verbal, Performance, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and creatinine and were asked to provide blood samples for measuring blood lead and hemoglobin concentrations. Exposure to As from drinking water was associated with reduced intellectual function after adjustment for sociodemographic covariates and water Mn. Water As was associated with reduced intellectual function, in a dose-response manner, such that children with water As levels > 50 microg/L achieved significantly lower Performance and Full-Scale scores than did children with water As levels < 5.5 microg/L. The association was generally stronger for well-water As than for urinary As.
The recent outbreak of arsenic in groundwater of Bangladesh has prompted the widespread use of arsenic field kits. The kit involves the generation of arsine (AsH3) from inorganic arsenic species by reduction with Zn and HCl. The arsine then reacts with a test strip containing HgBr2 to produce a color that is compared with a color scale for quantitation. It is known that arsine gas is one of the most toxic substances known to man. The objective of this work is to measure the concentration of ambient arsine produced during the test and suggest a safe handling procedure. The analytical method is based on integrated AsH3 measurement by a single-point arsine monitor. The method can be used to measure 4−50 ppb arsenic in water with 10% in precision and accuracy. Experiments show that a typical test kit produces arsine with a 90% efficiency. The concentration of arsine produced even at low level can be more than 9 times above the 50 ppbv threshold limiting value (TLV). Actual kit experiments show that 50% of the arsine escapes the reaction cell during the test. We estimate that the maximum arsine concentration in the immediate vicinity of the kit can be more than 35 times TLV of arsine from a single experiment with 100 ppb total arsenic in solution. Particularly, field workers performing a large number of tests in highly affected areas are exposed to a much higher level of arsine. We suggest that the tests should be performed in well-ventilated places and that the worker should be provided with a gas mask to minimize arsine inhalation.
For countries such as Bangladesh with a significant groundwater arsenic problem, there is an urgent need for the arsenic-contaminated wells to be identified as soon as possible and for appropriate action to be taken. This will involve the testing of a large number of wells, potentially up to 11 million in Bangladesh alone. Field-test kits offer the only practical way forward in the timescale required. The classic field method for detecting arsenic (the ‘Gutzeit’ method) is based on the reaction of arsine gas with mercuric bromide and remains the best practical approach. It can in principle achieve a detection limit of about 10 μg l−1 by visual comparison of the coloured stain against a colour calibration chart. A more objective result can be achieved when the colour is measured by an electronic instrument. Attention has to be paid to interferences mainly from hydrogen sulfide. Due to analytical errors, both from the field-test kits and from laboratory analysis, some misclassification of wells is inevitable, even under ideal conditions. The extent of misclassification depends on the magnitude of the errors of analysis and the frequency distribution of arsenic observed, but is in principle predictable before an extensive survey is undertaken. For a country with an arsenic distribution similar to that of Bangladesh, providing care is taken to avoid sources of bias during testing, modern field-test kits should be able to reduce this misclassification to under 5% overall.
The objective of this study is to elucidate the association between high-arsenic artesian well water and cancers in endemic area of blackfoot disease, a unique peripheral vascular disease related to continuous arsenic exposure. As compared with the general population in Taiwan, both the standardized mortality ratio (SMR) and cumulative mortality rate were significantly high in blackfoot disease-endemic areas for cancers of bladder, kidney, skin, lung, liver, and colon. The SMRs for cancers of bladder, kidney, skin, lung, liver, and colon were 1100, 772, 534, 320, 170, and 160, respectively, for males, and 2009, 1119, 652, 413, 229, and 168, respectively, for females. A dose-response relationship was observed between SMRs of the cancers and blackfoot disease prevalence rate of the villages and townships in the endemic areas. SMRs of cancers were greater in villages where only artesian wells were used as the drinking water source than in villages using both artesian and shallow wells, and even greater than in villages using shallow wells only.
Studies in Taiwan and Argentina suggest that ingestion of inorganic arsenic from drinking water results in increased risks of internal cancers, particularly bladder and lung cancer. The authors investigated cancer mortality in a population of around 400,000 people in a region of Northern Chile (Region II) exposed to high arsenic levels in drinking water in past years. Arsenic concentrations from 1950 to the present were obtained. Population-weighted average arsenic levels reached 570 microg/liter between 1955 to 1969, and decreased to less than 100 microg/liter by 1980. Standardized mortality ratios (SMRs) were calculated for the years 1989 to 1993. Increased mortality was found for bladder, lung, kidney, and skin cancer. Bladder cancer mortality was markedly elevated (men, SMR = 6.0 (95% confidence interval (CI) 4.8-7.4); women, SMR = 8.2 (95% CI 6.3-10.5)) as was lung cancer mortality (men, SMR = 3.8 (95% CI 3.5-4.1); women, SMR = 3.1 (95% CI 2.7-3.7)). Smoking survey data and mortality rates from chronic obstructive pulmonary disease provided evidence that smoking did not contribute to the increased mortality from these cancers. The findings provide additional evidence that ingestion of inorganic arsenic in drinking water is indeed a cause of bladder and lung cancer. It was estimated that arsenic might account for 7% of all deaths among those aged 30 years and over. If so, the impact of arsenic on the population mortality in Region II of Chile is greater than that reported anywhere to date from environmental exposure to a carcinogen in a major population.
The groundwater in seven districts of West Bengal, India, covering an area of 37,000 km2 with a population of 34 million, has been contaminated with arsenic. In 830 villages/wards more than 1.5 million people, out of the total population, drink the arsenic-contaminated water. Safe water from a source having < 0.002 mg 1(-1) arsenic has been supplied for 2 years to five affected families comprising 17 members (eight of them with arsenical skin-lesions) of different age groups for impact assessment study in terms of loss of arsenic through urine, hair and nail. The study indicates random observable fluctuations of arsenic concentration in urine among members on different scheduled sampling days with a declining trend, particularly during the first 6 months. Furthermore, the investigation showed that despite having safe water for drinking and cooking, the study group could not avoid an intake of arsenic, time and again, through edible herbs grown in contaminated water, food materials contaminated through washing, and the occasional drinking of contaminated water. After minimizing the level of contamination, a noteworthy declining trend after 8 months was observed in urine, hair and nails in all the cases, but not to that level observed in a normal population, due to prevailing elevated background level of arsenic in the area. The eight members, who had already developed skin lesions, are far from recovering completely, indicating a long-lasting damage. Statistical interpretation of the data are considered.
This is the first publication on arsenic contamination of the Red River alluvial tract in the city of Hanoi and in the surrounding rural districts. Due to naturally occurring organic matter in the sediments, the groundwaters are anoxic and rich in iron. With an average arsenic concentration of 159 micrograms/L, the contamination levels varied from 1 to 3050 micrograms/L in rural groundwater samples from private small-scale tubewells. In a highly affected rural area, the groundwater used directly as drinking water had an average concentration of 430 micrograms/L. Analysis of raw groundwater pumped from the lower aquifer for the Hanoi water supply yielded arsenic levels of 240-320 micrograms/L in three of eight treatment plants and 37-82 micrograms/L in another five plants. Aeration and sand filtration that are applied in the treatment plants for iron removal lowered the arsenic concentrations to levels of 25-91 micrograms/L, but 50% remained above the Vietnamese Standard of 50 micrograms/L. Extracts of sediment samples from five bore cores showed a correlation of arsenic and iron contents (r2 = 0.700, n = 64). The arsenic in the sediments may be associated with iron oxyhydroxides and released to the groundwater by reductive dissolution of iron. Oxidation of sulfide phases could also release arsenic to the groundwater, but sulfur concentrations in sediments were below 1 mg/g. The high arsenic concentrations found in the tubewells (48% above 50 micrograms/L and 20% above 150 micrograms/L) indicate that several million people consuming untreated groundwater might be at a considerable risk of chronic arsenic poisoning.
Recent research in ES&T found that a popular analytical kit for determining the safety of well water in Bangladesh and India may be unreliable. Britt Erickson looks at the ramifications of these results and what alternative tests are available.
To understand the magnitude of the arsenic calamity in West Bengal, a detailed study spanning 7 years was made in North 24-Parganas, one of the nine arsenic affected districts. Area and population of North 24-Parganas district are 4093.82 sq. km and 7.3 million, respectively. Fourty eight thousand and thirty water samples were analyzed from hand tubewells of North 24-Parganas in use for drinking, cooking and 29.2% of the tubewells were found to have arsenic above 50 microg/L, the maximum permissible limit of World Health Organization (WHO) and 52.8% have arsenic above 10 microg/L, WHO recommended value of arsenic in drinking water. Out of the 22 blocks of North 24-Parganas, in 20 blocks arsenic has been found above the maximum permissible limit and so far in 16 blocks people have been identified as suffering from arsenical skin lesions. From the generated data, it is estimated that about 2.0 million and 1.0 million people are drinking arsenic contaminated water above 10 microg/L and 50 microg/L level, respectively in North 24-Parganas alone. So far, in our preliminary study 33,000 people have been examined at random from arsenic affected villages in North 24-Parganas and 2274 people have been registered with arsenical skin lesions. Extrapolation of the available data indicates about 0.1 million people may be suffering from arsenical skin lesions from North 24-Parganas alone. A sum of 21,000 hair, nail, and urine samples analyses from arsenic affected villages show 56%, 80%, and 87% people have arsenic in biological specimen more than normal/toxic (hair) level, respectively. Thus, many may be subclinically affected. Due to use of arsenic contaminated groundwater for agricultural irrigation, rice and vegetable are getting arsenic contaminated. Hence there is an additional arsenic burden from food chain. People from arsenic affected villages are also suffering from arsenical neuropathy. A followup study indicates that many of the victims suffering from severe arsenical skin lesions for several years are now suffering from cancer or have already died of cancer.
Searching for an optimum solution to the Bangladesh arsenic crisis: Thirty years ago Bangladesh experienced very high levels of infant and child mortality, much of it due to water-borne disease in deltaic conditions where surface water was highly polluted. In what appeared to be one of the great public health achievements, 95% of the population were converted to drinking bacteria-free tubewell water from underground aquifers. Recently, it has been shown that perhaps 20% of this water is arsenic contaminated and alternatives to tubewell water have been sought. This paper reports on two national surveys collaboratively carried out in 2000 by the Health Transition Centre, Australian National University and Mitra and Associates, Dhaka: A census of tubewells and a household survey of tubewell use and arseniosis. The study found that the tubewell revolution has been promoted not only by health considerations but also by the demand for a household water facility and the desire by women to reduce workloads associated with using surface water. Because of this, and because the population had absorbed the message about safe tubewell water, it is argued that the movement away from the use of tubewell water should be as limited as possible, even if this means using safe tubewells which are often found in the neighbourhood. To enable such a move the most urgent need is not changing the source of water but comprehensive national water testing providing essential information to households about which wells are safe and which are not.
A wide variety of tools are available, both parametric and nonparametric, for analyzing spatial data. However, it is not always clear how to translate statistical inferences into decision recommendations. This article explores the possibilities of estimating the effects of decision options using very direct manipulation of data, bypassing formal statistical analysis. We illustrate with the application that motivated this research, a study of arsenic in drinking water in nearly 5,000 wells in a small area in rural Bangladesh. We estimate the potential benefits of two possible remedial actions: (1) recommendations that people switch to nearby wells with lower arsenic levels; and (2) drilling new community wells. We use simple nonparametric clustering methods and estimate uncertainties using cross-validation.
Millions of people in Bangladesh have probably switched their water consumption to wells that meet the local standard for As in drinking water of 50 microg/L as a result of blanket field testing throughout the country. It is therefore important to know if As concentrations in those wells could change over time. To address this issue, we report here precise groundwater As analyses for time-series samples collected from a suite of 20 tube wells containing < or =50 microg/L As and ranging from 8 to 142 m in depth. For 17 out of 20 wells, the standard deviation of groundwater As concentrations was <10 microg/L over the 3-year monitoring period (n = 24-44 per well). Six of the 17 wells are community wells, each of which serves the needs of several hundred people in particularly affected villages. Of the three wells showing larger fluctuations in chemical composition including As, two are very shallow (8 and 10 m). Variations in As concentrations for one of these wells (50 +/- 32 microg/L, n = 36), as well as another shallow well showing smaller variations (48 +/- 5 microg/L, n = 36), appear to be coupled to seasonal precipitation and recharge linked to the monsoon. The other shallow well showing larger variations in composition indicates a worrisome and steady increase in As concentrations from 50 to 70 microg/L (n = 36) over 3 years. The time series of As (30 +/- 11 microg/L, n = 24) and other constituents in one deep community well (59 m) show large fluctuations that suggest entrainment of shallow groundwater through a broken PVC pipe. Even though the majority of wells that were initially safe remained so for 3 years, our results indicate that tube wells should be tested periodically.
A comparison of field and laboratory measurements of arsenic in groundwater of Araihazar, Bangladesh, indicates that the most widely used field kit correctly determined the status of 88% of 799 wells relative to the local standard of 50 µg/L As. Additional tests show that the inconsistencies, mainly underestimates in the 50-100 µg/L As range, can be avoided by increasing the reaction time from 20 to 40 min. Despite this limitation, the field data already compiled for millions of wells by the Bangladesh Arsenic Mitigation and Water Supply Project, in combination with information on well location and depth, should prove to be extremely useful to prioritize interventions in thousands of affected villages.
This study documents the response of 6500 rural households in a 25 km(2) area of Bangladesh to interventions intended to reduce their exposure to arsenic contained in well water. The interventions included public education, posting test results for arsenic on the wells, and installing 50 community wells. Sixty-five percent of respondents from the subset of 3410 unsafe wells changed their source of drinking water, often to new and untested wells. Only 15% of respondents from the subset of safe wells changed their source, indicating that health concerns motivated the changes. The geo-referenced data indicate that distance to the nearest safe well also influenced household responses.
Arsenic concentrations measured by graphite-furnace atomic absorption range from <5 to 900 ug/L in groundwater pumped from 6000 wells within a 25 km area of Bangladesh. The proportion of wells that exceed the local standard for drinking water of 50 ug/L arsenic increases with depth from 25% between 8-10 m to 75% between 15-30 m, then declines gradually to less than 10% at 90 m. Some villages within the study area do not have a single well that meets the standard, while others have wells that are nearly all acceptable. In contrast to the distribution of arsenic in the 8-30 m depth range which does not follow any obvious geological feature, the arsenic content of groundwater associated with relatively oxic Pleistocene sand deposits appears to be consistently low. The depth of drilling necessary to reach these low-As aquifers ranges from 30 to 120 m depth within the study area.
Combating a Deadly Menace: Early Experiences with a Community-Based Arsenic Mitigation Project in Bangladesh
- Brac
BRAC. Combating a Deadly Menace: Early Experiences with a Community-Based Arsenic Mitigation Project in Bangladesh; Research Monograph Series No. 16; Dhaka, Bangladesh, 2000.
Final Report, 10.1021/es050939q CCC: $30.25 © xxxx American Chemical Society VOL. xx, NO. xx, xxxx / ENVIRON. SCI. & TECHNOL. 9 A PAGE EST: 1.2 Published on Web 00/00/0000
- Dphe Arsenic
- Contamination
- Groundwater
- Bangladesh
- D G Kinniburgh
- P L Smedley
- Eds
BGS; DPHE. Arsenic Contamination of Groundwater in Bangladesh ; Kinniburgh, D. G., Smedley, P. L., Eds.; Final Report, 10.1021/es050939q CCC: $30.25 © xxxx American Chemical Society VOL. xx, NO. xx, xxxx / ENVIRON. SCI. & TECHNOL. 9 A PAGE EST: 1.2 Published on Web 00/00/0000 BGS Technical Report WC/00/19,; British Geological Survey: Keyworth, UK, 2001.
Arsenic Contamination of Groundwater in Bang-ladesh Final Report, 10.1021/es050939q CCC: $30.25 Published on Web 00/00/0000 xxxx American Chemical SocietyVOL. xx, NO. xx, xxxx / ENVIRON
- Bgs Dphe Kinniburgh
- D G Smedley
- P L Eds
BGS; DPHE. Arsenic Contamination of Groundwater in Bang-ladesh; Kinniburgh, D. G., Smedley, P. L., Eds.; Final Report, 10.1021/es050939q CCC: $30.25 Published on Web 00/00/0000 xxxx American Chemical SocietyVOL. xx, NO. xx, xxxx / ENVIRON. SCI. & TECHNOL.9A PAGE EST: 1.2 rBGS Technical Report WC/00/19,; British Geological Survey: Keyworth, UK, 2001.
- M M Rahman
- D P Mukherjee
- M K Sengupta
- U K Chowdhury
- D Lodh
- C R Chanda
- S Roy
- M Selim
- Q Q Zaman
- A H Milton
- S M Sahidulla
- M T Rahman
Rahman, M. M.; Mukherjee, D. P.; Sengupta, M. K.; Chowdhury,
U. K.; Lodh, D.; Chanda, C. R.; Roy, S.; Selim, M.; Zaman, Q.
Q.; Milton, A. H.; Sahidulla, S. M.; Rahman, M. T.; Chakraborti,
D. Effectiveness and Reliability of Arsenic Field Testing Kits:
Are the Million Dollar Screening Projects Effective or Not?
Environ. Sci. Technol. 2002, 36 (24), 5385-5394.
- van Geen A.