Tubewells and arsenic in Bangladesh: challenging a public health success story

Salinity and Water-Related Disease Risk in Coastal Bangladesh

An increase in surface and ground-water salinity due to climate change is reported to have become a great threat to the health of coastal inhabitants in Bangladesh. However, little is known about how much such salinity affects the risk of water-related diseases and how such risk can be mitigated in the field. This research examines the association between water-related diseases and coastal salinity along with sociodemographic and anthropometric factors. We conduct questionnaire surveys with 527 households: 273 subjects from the non-salinity and 254 subjects from the salinity rural coastal areas of Bangladesh. The logistic regression analysis demonstrates that the probability of suffering from water-borne, water-washed and water-related diseases are 8%, 14% and 11% higher in the salinity areas than in the non-salinity areas, respectively. However, it is also identified that people who consume rainwater as a drinking source even in the salinity areas have less chances and people who belong to "underweight body mass index" have more chances of being affected by water-related diseases. Overall, the results suggest that the long-term reservation of rainwater and addressing community-based food security & nutrition programs shall be effective countermeasures to reduce the risk of health problems in the coastal population and to sustain their lives even under the threat of land salinity.

Medical Hydrogeology of Asian Deltas: Status of Groundwater Toxicants and Nutrients, and Implications for Human Health

Drinking water, a fluid primarily for human hydration, is also a source of mineral nutrients. Groundwater, a drinking water source for more than 70% of inhabitants living in Asian deltas, has received much attention because of its naturally occurring arsenic, but the linkage of arsenic toxicity with other water constituents has not been studied. In addition, although nutrients are generally provided by food, in under developed rural settings, where people subsist on low nutrient diets, drinking-water-nutrients may supply quantities critical to human health thereby preventing diseases. Here, we show, using augmented datasets from three Asian deltas (Bengal, Mekong, and Red River), that the chemical content of groundwater is so substantial that in some areas individuals obtain up to 50% or more of the recommended daily intake (RDI) of some nutrients (e.g., calcium, magnesium, iron) from just two litres of drinking water. We also show some indications of a spatial association of groundwater nutrients and health outcome using demographic health data from Bangladesh. We therefore suggest that an understanding of the association of non-communicable disease and poor nutrition cannot be developed, particularly in areas with high levels of dissolved solids in water sources, without considering the contribution of drinking water to nutrient and mineral supply.

Effectiveness of solar disinfection (SODIS) in rural coastal Bangladesh

Scarcity of drinking water in the coastal area of Bangladesh compels the inhabitants to be highly dependent on alternative water supply options like rainwater harvesting system (RWHS), pond sand filter (PSF), and rain-feed ponds. Susceptibility of these alternative water supply options to microbial contamination demands a low-cost water treatment technology. This study evaluates the effectiveness of solar disinfection (SODIS) to treat drinking water from available sources in the southwest coastal area of Bangladesh. A total of 50 households from Dacope upazila in Khulna district were selected to investigate the performance of SODIS. Data were collected in two rounds to examine fecal coliform (FC) and Escherichia coli (E. coli) contamination of drinking water at the household water storage containers and SODIS bottles, and thereby determined the effectiveness of SODIS in reducing fecal contamination. All water samples were analyzed for pH, electrical conductivity, turbidity and salinity. SODIS significantly reduced FC and E. coli contamination under household conditions. The median health risk reduction by SODIS was more than 96 and 90% for pond and RWHS, respectively. Besides, turbidity of the treated water was found to be less than 5 NTU, except pond water. Only 34% of the participating households routinely adopted SODIS during the study.

Associations of total arsenic in drinking water, hair and nails with serum vascular endothelial growth factor in arsenic-endemic individuals in Bangladesh

Arsenic exposure is associated with cancer and vascular diseases. Angiogenesis is an important step for the pathological development of cancer and vascular diseases. Vascular endothelial growth factor (VEGF) is a specific marker for angiogenesis. However, human study showing the association between arsenic exposure and serum VEGF levels has not yet been documented. This study was aimed to investigate the association between arsenic exposure and serum VEGF levels in the arsenic-endemic individuals in Bangladesh. A total of 260 individuals were recruited for this study. Arsenic exposure levels were measured by ICP-MS and VEGF levels were quantified using VEGF immunoassay kit. The study subjects were stratified into tertile (low, medium and high) groups based on the arsenic in water, hair and nails. Serum VEGF levels were correlated with water (rs = 0.363, p < 0.001), hair (rs = 0.205, p < 0.01) and nail (rs = 0.190, p < 0.01) arsenic. Further, VEGF levels showed dose-response relationships with water, hair and nail arsenic. Mean VEGF levels in ⩽ 10 μg L(-1), 10.1-50 μg L(-1) and > 50 μg L(-1) groups were 91.84, 129.54, and 169.86 pg mL(-1), respectively, however, significant (p < 0.01) difference in VEGF levels was only found in > 50 μg L(-1) versus ⩽ 10 μg L(-1) groups. Significant associations of arsenic exposure with VEGF levels were found even after adjusting with relevant covariates. Therefore, these results provide evidence that arsenic exposure has a pro-angiogenic effect on humans, which may be implicated in arsenic-induced tumorigenesis and vascular diseases.

Elevated levels of plasma uric acid and its relation to hypertension in arsenic-endemic human individuals in Bangladesh

Blood uric acid has been recognized as a putative marker for cardiovascular diseases (CVDs). CVDs are the major causes of arsenic-related morbidity and mortality. However, the association of arsenic exposure with plasma uric acid (PUA) levels in relation to CVDs has not yet been explored. This study for the first time demonstrated the associations of arsenic exposure with PUA levels and its relationship with hypertension. A total of 483 subjects, 322 from arsenic-endemic and 161 from non-endemic areas in Bangladesh were recruited as study subjects. Arsenic concentrations in the drinking water, hair and nails of the study subjects were measured by inductively coupled plasma mass spectroscopy. PUA levels were measured using a colorimetric method. We found that PUA levels were significantly (p<0.001) higher in males and females living in arsenic-endemic areas than those in non-endemic area. Arsenic exposure (water, hair and nail arsenic) levels showed significant positive correlations with PUA levels. In multiple regression analyses, arsenic exposure levels were found to be the most significant contributors on PUA levels among the other variables that included age, body mass index, blood urea nitrogen, and smoking. There were dose-response relationships between arsenic exposure and PUA levels. Furthermore, diastolic and systolic blood pressure showed significant positive correlations with PUA levels. Finally, the average PUA levels were significantly higher in the hypertensive group than those in the normotensive group in both males and females living in arsenic-endemic areas. These results suggest that arsenic exposure-related elevation of PUA levels may be implicated in arsenic-induced CVDs.

Evolution of households' responses to the groundwater arsenic crisis in Bangladesh: information on environmental health risks can have increasing behavioral impact over time

A national campaign of well testing through 2003 enabled households in rural Bangladesh to switch, at least for drinking, from high-arsenic wells to neighboring lower-arsenic wells. We study the well-switching dynamics over time by re-interviewing, in 2008, a randomly selected subset of households in the Araihazar region who had been interviewed in 2005. Contrary to concerns that the impact of arsenic information on switching behavior would erode over time, we find that not only was 2003-2005 switching highly persistent but also new switching by 2008 doubled the share of households at unsafe wells who had switched. The passage of time also had a cost: 22% of households did not recall test results by 2008. The loss of arsenic knowledge led to staying at unsafe wells and switching from safe wells. Our results support ongoing well testing for arsenic to reinforce this beneficial information.

Protective benefits of deep tube wells against childhood diarrhea in Matlab, Bangladesh

OBJECTIVES

We investigated whether deep tube wells installed to provide arsenic-free groundwater in rural Bangladesh have the added benefit of reducing childhood diarrheal disease incidence.

METHODS

We recorded cases of diarrhea in children younger than 5 years in 142 villages of Matlab, Bangladesh, during monthly community health surveys in 2005 and 2006. We surveyed the location and depth of 12,018 tube wells and integrated these data with diarrhea data and other data in a geographic information system. We fit a longitudinal logistic regression model to measure the relationship between childhood diarrhea and deep tube well use. We controlled for maternal education, family wealth, year, and distance to a deep tube well.

RESULTS

Household clusters assumed to be using deep tube wells were 48.7% (95% confidence interval = 27.8%, 63.5%) less likely to have a case of childhood diarrhea than were other household clusters.

CONCLUSIONS

Increased access to deep tube wells may provide dual benefits to vulnerable populations in Matlab, Bangladesh, by reducing the risk of childhood diarrheal disease and decreasing exposure to naturally occurring arsenic in groundwater.

Approaches to increase arsenic awareness in Bangladesh: an evaluation of an arsenic education program

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 postintervention 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.

Arsenic and chromium in sea foods from Niger Delta of Nigeria: a case study of Warri, Delta State

This study determined the concentration of Arsenic and Chromium in sea foods samples from Ethiope River. The sea foods were bought from different locations along the bank of the river. Arsenic concentration ranged from 0.046 ± 0.01 to 0.083 ± 0.05 mg/kg, while the chromium concentration ranged from 0.079 ± 0.04 to 0.152 ± 0.14 mg/kg. Palaemon serratus has the highest concentration of arsenic and chromium, 152 ± 0.14 mg/kg and 0.081 ± 0.04 mg/kg respectively, while Harengula jaguana has the lowest concentration of arsenic and chromium, 0.079 ± 0.04 mg/kg and 0.046 ± 0.01 mg/kg respectively. There are various oil prospecting companies and oil and gas related industries in this area which discharge untreated waste products into Ethiope River. In view of this, there is need to determine the level of arsenic and chromium contamination of the river, since the inhabitants depend on the river for fishing and other domestic uses.

A cluster-based randomized controlled trial promoting community participation in arsenic mitigation efforts in Bangladesh

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.

A multi-criteria approach for assessing options to remediate arsenic in drinking water

The identification of best practice technologies to remediate arsenic-enriched drinking water involves the resolution of several technical, environmental, economic, and social factors. Multi-criteria analysis (MCA) provides a procedure to sort through diverse influencing factors as a means of facilitating the stakeholder decision-making process. The primary key MCA criteria used to define arsenic treatment options are expressed as source-exposure vector, health risk, cost, social acceptance, and technical competency. MCA not only can handle a complex mix of quantitative and qualitative information but also fosters means to resolve conflicting stakeholder opinion (or strategies). The MCA procedure involves construction of a performance matrix from utility scores for each key performance indicator (KPIs) that may influence outcomes. Data in the performance matrix are converted into numerical values through application of a specific utility scale scoring and weighting technique for each criterion. Inspection of the performance matrix scores facilitates decision making because they summarize arsenic treatment options numerically for all important criteria and KPIs. The weighting procedure enables stakeholder preferences (or strategies) to be incorporated into the selection process. Given the "fuzzy logic" nature of the KPI information, uncertainty may influence data outcome; this can be addressed by using an outranking procedure such as ELECTRE III or a simpler "swing" pairwise preference method. Sensitivity analysis can also be performed by reiterating the analysis using different utility scores and/or weights to assess influence on performance matrix outcomes. This approach enables the MCA methodology to be used as a negotiating tool in the decision-making process and allows areas of stakeholder agreement and disagreement to be highlighted.

Critical pathway analysis to determine key uncertainties in net impacts on disease burden in Bangladesh of arsenic mitigation involving the substitution of arsenic bearing for groundwater drinking water supplies

It has been increasingly recognised that calculation of the disease burden due to populations, such as in Bangladesh, extensively using hazardous arsenic bearing well waters, must explicitly account for the trade-off between diarrhoeal disease incidence and that of arsenic-related diseases. This is because it is likely that moves to alternative drinking water sources, be they surface waters or even more distant groundwaters, without further mitigation would result in a concurrent increase in diarrhoeal disease. In this paper, we update the model of Lokuge of the effects of such arsenic mitigation on disease burden in Bangladesh, using updated population data and background disease estimates. We run a critical pathway analysis on the model using Standardised Mortality Ratios (SMRs) for diabetes mellitus and ischemic heart disease from different epidemiological studies recently reviewed by Navas-Acien. Our analysis agrees with that of Lokuge that mitigation simply involving the substitution of a range of surface waters for well water sources with As > 50 microg/L would have a net positive impact on disease burden, as determined by deaths and Disability Life Adjusted Years (DALYs). In contrast, however, there is considerable ambiguity in the analogous results for mitigation for all the population exposed to well water with As > 10 microg/L. Depending upon the data source chosen for diabetes mellitus and ischaemic heart disease SMRs, such mitigation is modelled to have either a positive or a negative net impact on overall disease burden. The modelled negative impacts are entirely commensurate with the rationale for seeking groundwater as an alternative to surface waters as a drinking water supply, and highlight the practical requirement for multiple mitigation strategies, including those directed at ensuring the microbiological safety and continued protection of any alternative water supplies. Our study highlights the need for (i) adequate epidemiological studies involving multiple exposure categories, ideally resulting in an accurate dose-response relationship for arsenic uptake and the non-malignant high incidence conditions diabetes mellitus and ischemic heart disease for individuals with the socioeconomic and nutritional status of the Bangladeshi populations, and (ii) refined estimates of the diarrhoel disease burden arising from usage of surface waters.

Screening of arsenic in tubewell water with field test kits: evaluation of the method from public health perspective

There is an urgent need for Bangladesh to identify the arsenic (As) contaminated tubewells (TWs) in order to assess the health risks and initiate appropriate mitigation measures. This will involve testing water in millions of TWs and raising community awareness about the health problems related to chronic As exposure from drinking water. Field test kits offer the only practical tool within the time frame and financial resources available for screening and assessment of the As contaminated TWs as well as their monitoring than that of the laboratory measurement. A comparison of field test kit and laboratory measurements by AAS as "gold standard" for As in water of 12,532 TWs in Matlab Upazila in Bangladesh, indicates that the field kit correctly determined the status of 91% of the As levels compared to the Bangladesh Drinking Water Standard (BDWS) of 50 microg/L, and 87% of the WHO guideline value of 10 microg/L. Nevertheless, due to analytical and human errors during the determination of As by the field test kits, some misclassification of wells is inevitable. Cross-checking of the field test kit results, both by Field Supervisor and by the laboratory analyses reveal considerable discrepancies in the correct screening mainly at As concentration ranges of 10-24.9 microg/L and 50-99.9 microg/L, critical from a public health point of view. The uncertainties of misclassification of these two groups of TWs have severe public health implications due to As exposure from drinking water sources. This can be reduced through proper training of the field personnel, cross verification of the field test kit results with laboratory analyses and further development of the field test kits to determine As at low concentrations.

Treatment delay period: The case of arsenicosis in rural Bangladesh

Arsenic concentrations of tubewell water that exceed acceptable limits poses a serious health problem in Bangladesh. Many Bangladeshis are now suffering from arsenic-related diseases. The objectives of this paper are to examine the extent of delay in seeking medical treatment by victims of arsenic poisoning and to identify factors contributing to this delay. Questionnaire survey successfully administered to 663 victims living in two rural areas of Bangladesh provided the major data source for this study. Analysis of survey data reveal that median delay period was 12 months, but the delay period ranged from 1 month to 18 years. Because of this extremely large range, the mean delay period was about 22 months. The study identified time of identification of symptoms of arsenicosis as the most significant determinant of treatment delay followed by treatment sought from members of mobile medical teams, perceived threat, and level of education. Based on the study findings, it is recommended that the Bangladesh government and NGOs involved in arsenic mitigation and prevention efforts should educate individuals at risk for arsenic poisoning about the benefits of seeking early treatment. This study also recommends to continue to dispatch mobile medical teams to the arsenic-impacted areas.

Responses of 6500 households to arsenic mitigation in Araihazar, Bangladesh

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 contamination awareness among the rural residents in Bangladesh

Arsenic poisoning of tubewell water, which constitutes the primary source of drinking water, has become the greatest health threat to the people of rural Bangladesh. Somewhere between 35 to 57 million people in the country are now suspected of being affected by drinking water contaminated with arsenic. While the Bangladesh government, non-government organizations (NGOs), and bilateral and multilateral assistance agencies are involved in combating this dreadful problem, all of their efforts to date have proceeded without having grassroots information about arsenic poisoning. The objectives of this study are to investigate the level of knowledge rural residents have regarding arsenic poisoning and to identify the correlates of that knowledge. Questionnaire surveys administered among residents of four rural areas in Bangladesh provided the major data source for this study. Twenty villages were selected from moderate and low arsenic risk regions and a total of 356 respondents, 177 from medium risk regions and 179 from low risk regions, were interviewed. Analysis of the survey data reveals that arsenic awareness is currently not widespread in the study villages, particularly in the low arsenic risk region. There are also gaps in arsenic knowledge regarding the diseases caused by arsenic poisoning and mitigating measures available to prevent contamination. This study identified arsenic risk region, level of education, gender, and age as important determinants of arsenic knowledge. The findings of this study will aid in making existing health education programs more effective and in reducing the risk of developing arsenic-related illnesses.

The effect of arsenic mitigation interventions on disease burden in Bangladesh

Many interventions have been advocated to mitigate the impact of arsenic contamination of drinking water in Bangladesh. However, there are few data on the true magnitude of arsenic-related disease in Bangladesh nationally. There has also been little consideration given to possible adverse effects of such interventions, in particular, diarrheal disease. The purpose of this study was to estimate and compare the likely impacts of arsenic mitigation interventions on both arsenic-related disease and water-borne infectious disease. We found that arsenic-related disease currently results in 9,136 deaths per year and 174,174 disability-adjusted life years (DALYs; undiscounted) lost per year in those exposed to arsenic concentrations > 50 microg/L. This constitutes 0.3% of the total disease burden in Bangladesh in terms of undiscounted DALYs. We found intervention to be of overall benefit in reducing disease burden in most scenarios examined, but the concomitant increase in water-related infectious disease significantly reduced the potential benefits gained from intervention. A minimum reduction in arsenic-related DALYs of 77% was necessary before intervention achieved any reduction in net disease burden. This is assuming that interventions were provided to those exposed to > 50 microg/L and would concomitantly result in a 20% increase in water-related infectious disease in those without access to adequate sanitation. Intervention appears to be justified for those populations exposed to high levels of arsenic, but it must be based on exposure levels and on the effectiveness of interventions not only in reducing arsenic but in minimizing risk of water-related infections. Key words: arsenic/adverse effects, Bangladesh, burden of disease, diarrhea, risk assessment, water pollutants, water supply.