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The objective of this study was to design and evaluate a household-level arsenic education and well water arsenic testing intervention to increase arsenic awareness in Bangladesh. The authors randomly selected 1,000 study respondents located in 20 villages in Singair, Bangladesh. The main outcome was the change in knowledge of arsenic from baseline to follow-up 4 to 6 months after the household received the intervention. This was assessed through a pre- and post-intervention quiz concerning knowledge of arsenic. Respondents were between 18 and 102 years of age, with an average age of 37 years; 99.9% were female. The knowledge of arsenic quiz scores for study participants were significantly higher at follow-up compared with baseline. The intervention was effective in increasing awareness of the safe uses of arsenic-contaminated water and dispelling the misconception that boiling water removes arsenic. At follow-up, nearly all respondents were able to correctly identify the meaning of a red (contaminated) and green (arsenic safe) well relative to arsenic (99%). The educational program also significantly increased the proportion of respondents who were able to correctly identify the health implications of arsenic exposure. However, the intervention was not effective in dispelling the misconceptions in the population that arsenicosis is contagious and that illnesses such as cholera, diarrhea, and vomiting could be caused by arsenic. Further research is needed to develop effective communication strategies to dispel these misconceptions. This study demonstrates that a household-level arsenic educational program can be used to significantly increase arsenic awareness in Bangladesh. (Contains 4 tables.)

OBJECTIVE: To monitor the effectiveness of deep community wells in reducing exposure to elevated levels of arsenic in ground-water pumped from shallower aquifers. METHODS: 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. FINDINGS: The mean arsenic concentration in water pumped from wells already in use in the villages where the community wells, were installed was 180 ± 140 µg/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 µg/l for drinking-water. One of these wells met the Bangladesh standard of 50 µg/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. CONCLUSION: 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.

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. Plain Language Summary: Arsenic contaminates groundwater across much of Bangladesh, poisoning millions of people who rely on well water for drinking. Well‐switching programs have proved useful for lowering arsenic exposures. In well‐switching programs, households with high‐arsenic wells switch to nearby wells with low arsenic for drinking. However, several important questions remain for designing future well‐switching programs: Do inexpensive field kits provide sufficiently accurate arsenic concentration measurements for determining which wells are safe and which are unsafe? What arsenic concentration is the best threshold for designating wells as safe? In this analysis, we use two large datasets from Ariahazar Bangladesh, a district where the arsenic problem has been extensively studied. Our results indicate that the average decline in arsenic exposure for a switching program that is based on cheap kit measurements is comparable to that of a program that uses more accurate, but expensive and logistically challenging, laboratory measurements. We also show that the 50 μg/L threshold used in Bangladesh to distinguish safe and unsafe wells is close to the optimal value for reducing arsenic exposure. These findings will be useful to the government of Bangladesh that is about to launch a new blanket testing campaign of millions of wells using field kits. Key Points: Well‐switching based on kit or laboratory measurements produces similar reductions in arsenic exposureThe optimal well switching threshold for reducing arsenic exposure is near 50 μg/L, higher than the WHO guideline of 10 μg/LProviding actual kit readings instead of classifying wells as just "unsafe" or "safe" could lead to a higher reduction in arsenic exposure [ABSTRACT FROM AUTHOR]

Abstract Objective To reduce arsenic (As) exposure, we evaluated the effectiveness of training community members to perform water arsenic (WAs) testing and provide As education compared to sending representatives from outside communities to conduct these tasks. Methods We conducted a cluster based randomized controlled trial of 20 villages in Singair, Bangladesh. Fifty eligible respondents were randomly selected in each village. In 10 villages, a community member provided As education and WAs testing. In a second set of 10 villages an outside representative performed these tasks. Results Overall, 53% of respondents using As contaminated wells, relative to the Bangladesh As standard of 50 μg/L, at baseline switched after receiving the intervention. Further, when there was less than 60% arsenic contaminated wells in a village, the classification used by the Bangladeshi and UNICEF, 74% of study households in the community tester villages, and 72% of households in the outside tester villages reported switching to an As safe drinking water source . Switching was more common in the outside-tester (63%) versus community-tester villages (44%). However, after adjusting for the availability of arsenic safe drinking water sources, well switching did not differ significantly by type of As tester (Odds ratio =0.86[95% confidence interval 0.42-1.77). At follow-up, among those using As contaminated wells who switched to safe wells, average urinary As concentrations significantly decreased. Conclusion The overall intervention was effective in reducing As exposure provided there were As-safe drinking water sources available. However, there was not a significant difference observed in the ability of the community and outside testers to encourage study households to use As-safe water sources. The findings of this study suggest that As education and WAs testing programs provided by As testers, irrespective of their residence, could be used as an effective, low cost approach to reduce As exposure in many As-affected areas of Bangladesh.

Abstract Background In many areas of Bangladesh, it has been more than six years since a national campaign to test tubewells for arsenic (As) was conducted. Many households therefore draw their water for drinking and cooking from untested wells. Methods A household drinking water survey of 6646 households was conducted in Singair upazilla of Bangladesh. A subset of 795 untested wells used by 1000 randomly selected households was tested in the field by trained village workers with the Hach EZ kit, using an extended reaction time of 40 min, and in the laboratory by high-resolution inductively-coupled plasma-mass spectrometry (HR ICP-MS). Results The household survey shows that more than 80% of the wells installed since the national testing campaign in this area were untested. Less than 13% of the households with untested wells knew where a low-As well was located near their home. Village workers using the Hach EZ kit underestimated the As content of only 4 out of 795 wells relative to the Bangladesh standard. However, the As content of 168 wells was overestimated relative to the same threshold. Conclusion There is a growing need for testing tubewells in areas of Bangladesh where As concentrations in groundwater are elevated. This could be achieved by village workers trained to use a reliable field kit. Such an effort would result in a considerable drop in As exposure as it increases the opportunities for well switching by households.

Abstract: The arsenic (As) content of groundwater pumped from all tubewells within 61 contiguous villages of Araihazar, Bangladesh, was determined a first time in 2000–01 with laboratory measurements and a second time in 2012–13 using the ITS Arsenic Econo-Quick kit. The two surveys indicate that the total number of tubewells within the area almost doubled from 5560 to 10,879 over 12years. The evolution of the distribution of well ages between the two surveys is consistent with a simple model that combines an annual increase of 42wells/year in the rate of installations within the 61 villages starting in 1980 and a 7%/year rate of abandonment of wells as a function of well age. Colored placards were posted on each pumphead in 2012–13 on the basis of the kit results relative to the WHO guideline for As and the Bangladesh standard for As in drinking water: blue for As≤10μg/L, green>10–50μg/L, and red: >50μg/L. According to quality-control samples collected from 502 tubewells for comparing the kit results with laboratory measurements, not a single well labeled blue in 2012–13 should have been labeled red and vice-versa. Field-kit testing in 2012–13 did not change the status of wells relative to the Bangladesh standard of 876 (87%) out of 1007 wells with a placard based on laboratory measurements in 2000–01 still attached to the pumphead. The high proportion of tubewells believed by households to be unsafe (66% out of 2041) that were still used for drinking and cooking in 2012–13 underlines the need for more widespread testing to identify low-As wells as an alternative source of drinking water. [Copyright &y& Elsevier]

The authors conducted a cross-sectional study to assess the relation between arsenic exposure from drinking water and plasma levels of markers of systemic inflammation and endothelial dysfunction (matrix metalloproteinase-9, myeloperoxidase, plasminogen activator inhibitor-1, soluble E-selectin, soluble intercellular adhesion molecule-1 (ICAM-1), and soluble vascular adhesion molecule-1 (VCAM-1)) using baseline data from 668 participants (age, >30 years) in the Health Effects of Arsenic Longitudinal Study in Bangladesh (2007–2008). Both well water arsenic and urinary arsenic were positively associated with plasma levels of soluble VCAM-1. For every 1-unit increase in log-transformed well water arsenic (ln μg/L) and urinary arsenic (ln μg/g creatinine), plasma soluble VCAM-1 was 1.02 (95% confidence interval: 1.01, 1.03) and 1.04 (95% confidence interval: 1.01, 1.07) times greater, respectively. There was a significant interaction between arsenic exposure and higher body mass index, such that the increased levels of plasminogen activator inhibitor-1 and soluble VCAM-1 associated with arsenic exposure were stronger among people with higher body mass index. The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation and endothelial dysfunction that could be modified by body mass index and also suggest a potential mechanism underlying the association between arsenic exposure and cardiovascular disease. [ABSTRACT FROM PUBLISHER]

The retention and release of total coliforms and Escherichia coil was investigated in hand-pumps removed from tubewells tapping a faecally contaminated aquifer in Matlab, Bangladesh, and from a new hand-pump deliberately spiked with E. coil. All hand-pumps were connected to reservoirs of sterile water and flushed. Faecal coliforms were observed in the discharge from all three of the previously used hand-pumps, at concentrations comparable to levels measured in discharge when they were attached to the tubewells. During daily flushing of one of the previously used hand-pumps, the concentration of total coliforms in the discharge remained relatively constant (≈103 MPN/100 mL). Concentrations of E. coil in the pump discharge declined over time, but E. coil was still detectable up to 29 days after the start of flushing. In the deliberately spiked hand-pump, E. coil was observed in the discharge over 125 days (t50 = 8 days) and found to attach preferentially to elastomeric materials within the hand-pump. Attempts to disinfect both the village and new hand-pumps using shock chlorination were shown to be unsuccessful. These results demonstrate that hand-pumps can act as persistent reservoirs for microbial indicator bacteria. This could potentially influence drinking water quality and bias testing of water quality. [ABSTRACT FROM AUTHOR]

Background: Several reports indicate that drinking water arsenic (WAs) and manganese (WMn) are associated with children's intellectual function. Very little is known, however, about possible associations with other neurologic outcomes such as motor function. Methods: We investigated the associations of WAs and WMn with motor function in 304 children in Bangladesh, 8-11 years of age. We measured As and Mn concentrations in drinking water, blood,urine, and toenails. We assessed motor function with the Bruininks-Oseretsky test, version 2, in four subscales-fine manual control (FMC), manual coordination (MC), body coordination (BC), and strength and agility-which can be summarized with a total motor composite score (TMC). Results: Log-transformed blood As was associated with decreases in TMC [β = -3.63; 95% confidence interval (CI): -6.72, -0.54; p < 0.01], FMC (β = -1.68; 95% CI: -3.19, -0.18; p < 0.05), and BC (β = -1.61; 95% CI: -2.72, -0.51; p < 0.01), with adjustment for sex, school attendance, head circumference, mother's intelligence, plasma ferritin, and blood Mn, lead, and selenium. Other measures of As exposure (WAs, urinary As, and toenail As) also were inversely associated with motor function scores, particularly TMC and BC. Square-transformed blood selenium was positively associated with TMC (β = 3.54; 95% CI: 1.10, 6.0; p < 0.01), FMC (β = 1.55; 95% CI: 0.40, 2.70; p < 0.005), and MC (β= 1.57; 95% CI: 0.60, 2.75; p < 0.005) in the unadjusted models. Mn exposure was not significantly associated with motor function. Conclusion: Our research demonstrates an adverse association of As exposure and a protective association of Se on motor function in children. [ABSTRACT FROM AUTHOR]

In order to reduce the exposure to As naturally occurring in shallow groundwater of the Bengal Basin, tens of thousands of tubewells tapping deeper aquifers of the Bengal Basin have been installed. We address here lingering concerns that As concentrations in deep tubewells might increase over time with monitoring data spanning a period of up to 5 years for 51 community wells, 115-545 ft (34-164 m) deep, installed in Araihazar upazila, Bangladesh. This exceptionally detailed data set shows that all but 4 of these community wells have consistently provided drinking water that meets the Bangladesh standard for As in drinking water of 50 μg L- 1; all but 10 community wells have also consistently met the World Health Organization (WHO) guideline for As of 10 μ g L- 1. Groundwater pumped from one third of the community wells does not meet the current WHO guideline for Mn in drinking water of 0.4 mg L- 1, although Mn concentrations are lower than in most surrounding shallow wells. In addition to As and Mn, concentrations of 10 elements (Cr, Ni, Cu, Cd, Ba, Hg, Mo, Sb, Pb, and U) out of a total 19 inorganic constituents of potential health concern were monitored and found to be below their respective guideline values established by WHO. Further study is required to evaluate the health consequences of Mn exposure, but the increase in As concentrations in 4 community wells indicates that all deeper tubewells should be periodically re-tested. [ABSTRACT FROM AUTHOR]

BACKGROUND: Manganese is a common natural contaminant of groundwater in Bangladesh. In this cross-sectional study we assessed the association between water manganese and all-cause infant mortality in the offspring of female participants in the Health Effects of Arsenic Longitudinal Study Cohort. METHODS: In 2001, drinking water samples were collected, a history of well use was obtained, and a history of birth outcomes was ascertained. To avoid misclassification of exposure, women were included only if they had been drinking from the same well for most of their childbearing years (marriage years--well years ≤ 2). Of a total of 26,002 births (among 6,537 mothers), 3,837 children were born to women with this profile. The current analysis was based on the portion of these infants (n = 3,824) with recorded exposure and outcome status, 335 of whom died before reaching 1 year of age. RESULTS: Infants exposed to water manganese greater than or equal to the 2003 World Health Organization standard of 0.4 mg/L had an elevated mortality risk during the first year of life compared with unexposed infants [odds ratio (OR) = 1.8; 95% confidence interval (CI), 1.2-2.6]. Adjustment for water arsenic, indicators of social class, and other variables did not appreciably alter these results. When the population was restricted to infants born to recently married parents (marriage year 1991 or after), this elevation was more pronounced (OR = 3.4; 95% CI, 1.5-7.9). CONCLUSIONS: These preliminary findings indicate a possible association between manganese exposure and infant mortality. However, given the methodologic limitations of this study, the association needs to be confirmed through future work. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a need to identify and evaluate an effective mitigation program for arsenic exposure from drinking water in Bangladesh. OBJECTIVE: We evaluated the effectiveness of a multifaceted mitigation program to reduce As exposure among 11,746 individuals in a prospective cohort study initiated in 2000 in Araihazar, Bangladesh, by interviewing participants and measuring changes in urinary As levels. METHODS: The interventions included a) person-to-person reporting of well test results and health education; b) well labeling and village-level health education; and c) installations of 50 deep, low-As community wells in villages with the highest As exposure. RESULTS: Two years after these interventions, 58% of the 6,512 participants with unsafe wells (As = 50 µg) at baseline had responded by switching to other wells. Well labeling and village-level health education was positively related to switching to safe wells (As < 50 µg/L) among participants with unsafe wells [rate ratio (RR) = 1.84; 95% confidence interval (CI), 1.60-2.11] and inversely related to any well switching among those with safe wells (RR = 0.80; 95% CI, 0.66-0.98). The urinary As level in participants who switched to a well identified as safe (< 50 µg As/L) dropped from an average of 375 µg As/g creatinine to 200 µg As/g creatinine, a 46% reduction toward the average urinary As content of 136 µg As/g creatinine for participants that used safe wells throughout. Urinary As reduction was positively related to educational attainment, body mass index, never-smoking, absence of skin lesions, and time since switching (p for trend < 0.05). CONCLUSIONS: Our study shows that testing of wells and informing households of the consequences of As exposure, combined with installation of deep community wells where most needed, can effectively address the continuing public health emergency from arsenic in drinking water in Bangladesh. [ABSTRACT FROM AUTHOR]

Millions of persons around the world are exposed to low doses of arsenic through drinking water. However, estimates of health effects associated with low-dose arsenic exposure have been extrapolated from high-dose studies. In Bangladesh, many persons have been exposed to a wide range of doses of arsenic from drinking water over a significant period of time. The authors evaluated dose-response relations between arsenic exposure from drinking water and premalignant skin lesions by using baseline data on 11,746 participants recruited in 2000–2002 for the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh. Several measures of arsenic exposure were estimated for each participant based on well-water arsenic concentration and usage pattern of the wells and on urinary arsenic concentration. In different regression models, consistent dose-response effects were observed for all arsenic exposure measures. Compared with drinking water containing <8.1 μg/liter of arsenic, drinking water containing 8.1–40.0, 40.1–91.0, 91.1–175.0, and 175.1–864.0 μg/liter of arsenic was associated with adjusted prevalence odds ratios of skin lesions of 1.91 (95% confidence interval (CI): 1.26, 2.89), 3.03 (95% CI: 2.05, 4.50), 3.71 (95% CI: 2.53, 5.44), and 5.39 (95% CI: 3.69, 7.86), respectively. The effect seemed to be influenced by gender, age, and body mass index. These findings provide information that should be considered in future research and policy decisions. [ABSTRACT FROM AUTHOR]

The spatial heterogeneity of dissolved arsenic (As) concentrations in shallow groundwater of the Bengal Basin has been attributed to transport of As (and reactive carbon) from external sources or to the release of As from within grey sand formations. We explore the latter scenario in this detailed hydrological and geochemical study along a 300 m transect of a shallow aquifer extending from a groundwater recharge area within a sandy channel bar to its discharge into a nearby stream. Within the 10–20 m depth range, groundwater ages along the transect determined by the 3 H– 3 He method increase from <10 yr in the recharge area to a maximum of 40 yr towards the stream. Concentrations of groundwater As within the same grey sands increase from 10 to 100 to ∼500 μg/L along this transect. Evidence of reversible adsorption of As between the groundwater and sediment was obtained from a series of push–pull experiments, traditional batch adsorption experiments, and the accidental flooding of a shallow monitoring well. Assuming reversible adsorption and a distribution coefficient, K d , of 0.15–1.5 L/kg inferred from these observations, a simple flushing model shows that the increase in As concentrations with depth and groundwater age at this site, and at other sites in the Bengal and Red River Basins, can be attributed to the evolution of the aquifer over 100–1000 years as aquifer sands are gradually flushed of their initial As content. A wide range of As concentrations can thus be maintained in groundwater with increases with depth governed by the history of flushing and local recharge rates, without external inputs of reactive carbon or As from other sources. [ABSTRACT FROM AUTHOR]

Abstract: We conducted a randomized controlled trial in rural Bangladesh to examine how household drinking-water choices were affected by two different messages about risk from naturally occurring groundwater arsenic. Households in both randomized treatment arms were informed about the arsenic level in their well and whether that level was above or below the Bangladesh standard for arsenic. Households in one group of villages were encouraged to seek water from wells below the national standard. Households in the second group of villages received additional information explaining that lower-arsenic well water is always safer and these households were encouraged to seek water from wells with lower levels of arsenic, irrespective of the national standard. A simple model of household drinking-water choice indicates that the effect of the emphasis message is theoretically ambiguous. Empirically, we find that the richer message had a negative, but insignificant, effect on well-switching rates, but the estimates are sufficiently precise that we can rule out large positive effects. The main policy implication of this finding is that a one-time oral message conveying richer information on arsenic risks, while inexpensive and easily scalable, is unlikely to be successful in reducing exposure relative to the status-quo policy. [Copyright &y& Elsevier]

Abstract: Groundwater is routinely analyzed for fecal indicators but direct comparisons of fecal indicators to the presence of bacterial and viral pathogens are rare. This study was conducted in rural Bangladesh where the human population density is high, sanitation is poor, and groundwater pumped from shallow tubewells is often contaminated with fecal bacteria. Five indicator microorganisms (E. coli, total coliform, F+RNA coliphage, Bacteroides and human-associated Bacteroides) and various environmental parameters were compared to the direct detection of waterborne pathogens by quantitative PCR in groundwater pumped from 50 tubewells. Rotavirus was detected in groundwater filtrate from the largest proportion of tubewells (40%), followed by Shigella (10%), Vibrio (10%), and pathogenic E. coli (8%). Spearman rank correlations and sensitivity–specificity calculations indicate that some, but not all, combinations of indicators and environmental parameters can predict the presence of pathogens. Culture-dependent fecal indicator bacteria measured on a single date did not predict total bacterial pathogens, but annually averaged monthly measurements of culturable E. coli did improve prediction for total bacterial pathogens. A qPCR-based E. coli assay was the best indicator for the bacterial pathogens. F+RNA coliphage were neither correlated nor sufficiently sensitive towards rotavirus, but were predictive of bacterial pathogens. Since groundwater cannot be excluded as a significant source of diarrheal disease in Bangladesh and neighboring countries with similar characteristics, the need to develop more effective methods for screening tubewells with respect to microbial contamination is necessary. [Copyright &y& Elsevier]

Abstract: Drinking water manganese (WMn) is a potential threat to children''s health due to its associations with a wide range of outcomes including cognitive, behavioral and neuropsychological effects. Although adverse effects of Mn on cognitive function of the children indicate possible impact on their academic achievement little evidence on this issue is available. Moreover, little is known regarding potential interactions between exposure to Mn and other metals, especially water arsenic (WAs). In Araihazar, a rural area of Bangladesh, we conducted a cross-sectional study of 840 children to investigate associations between WMn and WAs and academic achievement in mathematics and languages among elementary school-children, aged 8–11 years. Data on As and Mn exposure were collected from the participants at the baseline of an ongoing longitudinal study of school-based educational intervention. Annual scores of the study children in languages (Bangla and English) and mathematics were obtained from the academic achievement records of the elementary schools. WMn above the WHO standard of 400μg/L was associated with 6.4% score loss (95% CI=−12.3 to −0.5) in mathematics achievement test scores, adjusted for WAs and other sociodemographic variables. We did not find any statistically significant associations between WMn and academic achievement in either language. Neither WAs nor urinary As was significantly related to any of the three academic achievement scores. Our finding suggests that a large number of children in rural Bangladesh may experience deficits in mathematics due to high concentrations of Mn exposure in drinking water. [Copyright &y& Elsevier]

Abstract: Recently, epidemiologic studies of developmental neurotoxicology have been challenged to increase focus on co-exposure to multiple toxicants. Earlier reports, including our own work in Bangladesh, have demonstrated independent associations between neurobehavioral function and exposure to both arsenic (As) and manganese (Mn) in school-aged children. Our earlier studies, however, were not designed to examine possible interactive effects of exposure to both As and Mn. To allow investigation of possible synergistic impact of simultaneous exposures, we recruited a new sample of 299 8–11 year old children, stratified by design on As (above and below 10μg/L) and Mn (above and below 500μg/L) concentrations of household wells. When adjusted only for each other, both As and Mn in whole blood (BAs; BMn) were significantly negatively related to most WISC-IV subscale scores. With further adjustment for socio-demographic features and ferritin, BMn remained significantly associated with reduced Perceptual Reasoning and Working Memory scores; associations for BAs, and for other subscales, were expectably negative, significantly for Verbal Comprehension. Urinary As (per gram creatinine) was significantly negatively associated with Verbal Comprehension scores, even with adjustment for BMn and other contributors. Mn by As interactions were not significant in adjusted or unadjusted models (all p''s>0.25). Findings are consistent with other reports documenting adverse impact of both As and Mn exposure on child developmental outcomes, although associations appear muted at these relatively low exposure levels. [Copyright &y& Elsevier]

Abstract: Exposure to arsenic (As)-contaminated drinking water affects millions of people worldwide. Arsenic exposure is associated with skin lesions, skin, lung, kidney and liver cancers, neurologic and cardiovascular effects. Past studies involving biomarkers of As exposure have typically examined urinary As (UAs) (adjusted for urinary creatinine), hair or toenail As, but not blood As (BAs) since blood concentrations are exceedingly low and are not detectable by conventional atomic absorption spectrophotometric techniques. In a case-cohort analysis of 303 newly diagnosed cases of skin lesions, and 849 subcohort members randomly selected from 8092 participants in the health effects of as longitudinal study (HEALS) in Araihazar, Bangladesh, we measured blood, urine and water As concentrations, and examined their associations with each other, and with the risk for skin lesions. BAs concentrations were highly correlated with creatinine-adjusted UAs concentrations (r =0.85) and with water As (WAs) (r =0.75). We observed consistent dose–response relationships between the risk of skin lesions and all the measures of As exposure. Rate ratios (RRs) for skin lesions by quintile of As exposure, adjusted for age and gender, revealed that the two highest quintiles were significantly related to an increased risk of skin lesions for each measure of exposure: BAs, UAs, WAs and a time-weighted water As variable. This prospective study confirms the increased risk of skin lesions in relation to As concentrations in blood, urine and water and also establishes that BAs is a useful biomarker of As exposure in this study population. [Copyright &y& Elsevier]

Groundwater flow has the potential to introduce arsenic (As) in previously uncontaminated aquifers. The extent to which As transport is retarded by adsorption is particularly relevant in Bangladesh where low-As wells offer the best chance of reducing chronic exposure to As of a large rural population dependent on groundwater. In this study, column experiments were conducted with intact cores in the field to measure As retardation. Freshly collected cores of reduced iron (Fe-II) dominated gray sediment of Holocene age as well as oxidized Fe (III)-coated orange sediment of Pleistocene age were eluted at pore-water velocities of 40–230 cm/day with anoxic groundwater pumped directly from a well and containing 320 μg/L As. Up to 100 μg/L As was immediately released from gray sand but the main As breakthrough for both gray and orange sand occurred between 30 and 70 pore volumes, depending on flow rate. The early release of As from gray sand is attributed to the presence of a weakly bound pool of As. The sorption of As was kinetically limited in both gray and orange sand columns. We used a reversible multi-reaction transport model to simulate As breakthrough curves while keeping the model parameters as constant as possible. Contrary to the notion that dissolved As is sorbed more strongly to orange sands, we show that As was similarly retarded in both gray and orange sands in the field. Image 1 • Freshly collected sediment cores were eluted in the field with pristine groundwater. • Transport of As is retarded by a factor of 30–35 relative to groundwater flow. • Adsorption of As is kinetically limited in both reduced and oxidized sediments. • A pool of weakly sorbed As is immediately eluted from the reduced gray sands. [ABSTRACT FROM AUTHOR]