Nine steps to risk-informed wellhead protection and management: a case study.

Wellhead-protection zones are commonly delineated on the basis of advective travel-time analysis without considering any aspects of model uncertainty. In the past decade, research efforts have produced quantifiable risk-based safety margins for protection zones. These margins are based on well-vulnerability criteria (e.g., travel times, exposure times, peak concentrations) and take model and parameter uncertainty into account. There are three main reasons why practitioners still refrain from applying these new techniques. (1) They fear the additional areal demand of probabilistic safety margins; (2) probabilistic approaches are allegedly complex, not readily available and require huge computing resources, and (3) uncertainty bounds are fuzzy, whereas final decisions are binary. The primary goal of this paper is to show that these reservations are unjustified. We present a straightforward, computationally affordable framework that offers risk-informed decision support for robust and transparent wellhead delineation under uncertainty. We show that reliability levels can be increased by exchanging delineated low-risk areas for previously nondelineated high-risk areas. We also show that further improvements may often be available with only little additional delineated area. As proof of our concept, we illustrate our key points with the example of a pumped karstic well catchment, located in Germany.

Assessment of the relationship between bacteriological quality of dug-wells, hygiene behaviour and well characteristics in two cholera endemic localities in Douala, Cameroon.

BACKGROUND: Access to potable water is grossly inadequate in Douala-Cameroon. The situation is worse in slum areas, compelling inhabitants to obtain water from sources of doubtful quality. This has contributed to frequent outbreaks of water-borne diseases particularly cholera, which results in severe morbidity and mortality. Shallow wells are a major source of water in these areas. We analyzed the influence of some factors on the bacteriological quality of well water in Bepanda and New Bell, cholera endemic localities in Douala to generate data that would serve as basis for strengthening of water and health policies. METHODS: Questionnaires were administered to inhabitants of study sites to appraise their hygiene and sanitation practices, and level of awareness of waterborne diseases. The bacteriological quality of water was determined by investigating bacterial indicators of water quality. Relationship between well characteristics and bacteriological quality of water was determined using χ² test. The Kendall tau_b nonparametric correlation was used to measure the strength of association between well characteristics and bacteriological parameters. Statistics were discussed at 95% confidence level. Antibiotic susceptibility of isolates was investigated by the Kirby-Bauer and broth dilution techniques. Multidrug resistant species were tested for extended ß-lactamase production potential. RESULTS: Inhabitants demonstrated adequate knowledge of waterborne diseases but employed inappropriate method (table salt) for well disinfection. Well construction and location violated guidelines. Indicator bacterial counts greatly exceeded the WHO guidelines. Variation in bacteriologic parameters between sites was not significant (P > 0.05) since well characteristics and hygiene and sanitary practices were similar. Differences in bacteriologic quality with respect to state of well, and presence of molded casing and lid, and height of casing were not significant (P > 0.05). Well distance from sanitary structure negatively correlated with bacteriological characteristics indicating it could be a major contributory factor to poor water quality. Bacteria isolated were predominantly enteric organisms. Ciprofloxacin was the most active agent. Extended ß-lactamase producers were detected among Salmonella species, Citrobacter fruendii and E. coli. CONCLUSION: Poor well location, construction, and hygiene and sanitary practices were among the factors affecting water quality. There is an urgent need for education of inhabitants on effective water disinfection strategies and for regular monitoring of wells.

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.

Arsenic in tube well water in Bangladesh: health and economic impacts and implications for arsenic mitigation.

A national drinking water quality survey conducted in 2009 furnished data that were used to make an updated estimate of chronic arsenic exposure in Bangladesh. About 20 million and 45 million people were found to be exposed to concentrations above the national standard of 50 µg/L and the World Health Organization's guideline value of 10 µg/L, respectively. From the updated exposure data and all-cause mortality hazard ratios based on local epidemiological studies, it was estimated that arsenic exposures to concentrations > 50 µg/L and 10-50 µg/L account for an annual 24,000 and perhaps as many as 19,000 adult deaths in the country, respectively. Exposure varies widely in the 64 districts; among adults, arsenic-related deaths account for 0-15% of all deaths. An arsenic-related mortality rate of 1 in every 16 adult deaths could represent an economic burden of 13 billion United States dollars (US$) in lost productivity alone over the next 20 years. Arsenic mitigation should follow a two-tiered approach: (i) prioritizing provision of safe water to an estimated 5 million people exposed to > 200 µg/L arsenic, and (ii) building local arsenic testing capacity. The effectiveness of such an approach was demonstrated during the United Nations Children's Fund 2006-2011 country programme, which provided safe water to arsenic-contaminated areas at a cost of US$ 11 per capita. National scale-up of such an approach would cost a few hundred million US dollars but would improve the health and productivity of the population, especially in future generations.

Sanitary inspection of wells using risk-of-contamination scoring indicates a high predictive ability for bacterial faecal pollution in the peri-urban tropical lowlands of Dar es Salaam, Tanzania.

Sanitary inspection of wells was performed according to World Health Organization (WHO) procedures using risk-of-contamination (ROC) scoring in the peri-urban tropical lowlands of Dar es Salaam, Tanzania. The ROC was assessed for its capacity to predict bacterial faecal pollution in the investigated well water. The analysis was based on a selection of wells representing environments with low to high presumptive faecal pollution risk and a multi-parametric data set of bacterial indicators, generating a comprehensive picture of the level and characteristics of faecal pollution (such as vegetative Escherichia coli cells, Clostridium perfringens spores and human-associated sorbitol fermenting Bifidobacteria). ROC scoring demonstrated a remarkable ability to predict bacterial faecal pollution levels in the investigated well water (e.g. 87% of E. coli concentration variations were predicted by ROC scoring). Physicochemical characteristics of the wells were not reflected by the ROC scores. Our results indicate that ROC scoring is a useful tool for supporting health-related well water management in urban and suburban areas of tropical, developing countries. The outcome of this study is discussed in the context of previously published results, and future directions are suggested.

Cancer incidence and pattern of arsenic concentration in drinking water wells in Córdoba, Argentina.

Cancer occurrence is associated with Arsenic (As) in drinking water. In Argentina, there are high As concentrations in groundwater but there is no published evidence yet of an association between geographic patterns of cancer incidence and the distribution of As in groundwater supplies. The purpose of this study is to assess the association between cancer incidence patterns and As in Córdoba province's aquifers. Age standardized incidence rates (ASIRs) were obtained from Córdoba Cancer Registry (CCR), and As data from official reports of monitoring wells. A multilevel model was applied. Total ASIRs by aquifers for males/females were 191.01/249.22 (Rioja plain); 215.03/225.37 (Pampa hills); and 239.42/188.93 (Chaco-Pampa plain). As was associated with increased risk of colon cancer in women, and lung and bladder cancers in both sexes. It had no association with breast cancer. ASIRs were related to As, controlling for unobserved heterogeneity. An overlapping pattern of higher As and higher risks was evident for lung, bladder and female colon cancers.

A large-scale study of bacterial contamination of drinking water and its public health impact in Nepal.

Bacterial contamination of drinking water is a major public health in Nepal. A large scale study on contamination of drinking water was done covering all three ecological belts (mountain, hill and Terai) in all five (eastern, central, western, mid-western and far-western) development regions of Nepal during 2009-2011. Of the total 506 water samples studied, one-forth (25.1%; 127/506) were visually turbid. Bacteriologically, 88.5% (448/506) samples were positive for total coliform (TC) whereas 56.5% (286/506) were positive for fecal coliform (FC) (Esch. coli). The TC positive rate ranged from 53.8% in Damak (Jhapa) to 100.0% in different districts. The FC positive rate varied more widely ranging from 10.0% in Bharatpur City (Chitawan) to 100.0% in Baglung Township (Baglung) with over 50.0% in most of the districts (over 75.0% in eight districts). Both TC and FC positive rate were highest in Far-western Development Region (DR). High TC positive rate (96.7%) in Far-western DR was followed by Western DR (93.9%), Eastern DR (89.2%), Central DR (87.0%) and Mid-western DR (74.6%). Highest FC positive rate (65.5%) in Far-western DR was followed by Med-western DR (63.5%), Western DR (55.9%), Central DR (53.2%) and Eastern DR (52.0%). TC positive was highest (90.7%) in hills followed by mountain (89.7%) and Terai (plain) (84.1%) belt. In contrast, FC positive rate was highest (66.2%) in mountain, followed by hills (58.0%) and Terai (49.7%). Of the total 506, 335 were piped tap water, 129 were boring water, 16 natural tap (spout), 16 were well (sallow/deep well) and 10 were mineral/uroguard treated water. TC positive rate was very high (81.2% to 100.0%) in different type water samples (piped tap: 90.1%; boring water: 85.2%; natural spout/tap: 81.2%; well water 100.0% and mineral water/uroguard treated water: 80.0%). FC positive rate ranged from 0.0% in mineral water/uroguard treated water to 93.7% in well water samples. These findings are of serious public health concern with regard to both endemicity and outbreak of waterborne diseases in the country.

Impact of tubewell access and tubewell depth on childhood diarrhea in Matlab, Bangladesh.

BACKGROUND: During the past three decades in Bangladesh, millions of tubewells have been installed to reduce the prevalence of diarrheal disease. This study evaluates the impacts of tubewell access and tubewell depth on childhood diarrhea in rural Bangladesh. METHODS: A total of 59,796 cases of diarrhea in children under 5 were recorded in 142 villages of Matlab, Bangladesh during monthly community health surveys between 2000 and 2006. The location and depth of 12,018 tubewells were surveyed in 2002-04 and integrated with diarrhea and other data in a geographic information system. A proxy for tubewell access was developed by calculating the local density of tubewells around households. Logistic regression models were built to examine the relationship between childhood diarrhea, tubewell density and tubewell depth. Wealth, adult female education, flood control, population density and the child's age were considered as potential confounders. RESULTS: Baris (patrilineally-related clusters of households) with greater tubewell density were associated with significantly less diarrhea (OR (odds ratio) = 0.87, 95% confidence interval (CI): 0.85-0.89). Tubewell density had a greater influence on childhood diarrhea in areas that were not protected from flooding. Baris using intermediate depth tubewells (140-300 feet) were associated with more childhood diarrhea (OR = 1.24, 95% CI: 1.19-1.29) than those using shallow wells (10-140 feet). Baris using deep wells (300-990 feet) had less diarrheal disease than those using shallow wells, however, the difference was significant only when population density was low (< 1000 person/km(2)) or children were at the age of 13-24 months. CONCLUSIONS: Increased access to tubewells is associated with a lower risk of childhood diarrhea. Intermediate- depth wells are associated with more childhood diarrhea compared to shallower or deeper wells. These findings may have implications for on-going efforts to reduce exposure to elevated levels of arsenic contained in groundwater that is pumped in this study area primarily from shallow tubewells.

[Comparative study of some clinical and laboratory indicators in a group of patients using wells as source of drinking water and a control group using safe water]. / Studiu comparativ al unor indicatori clinici si de laborator la un lot de subiecti care folosesc apa de fântâna ca sursa de apa potabila si un lot martor de subiecti care au sursa de apa potabila controlata sanitar.

UNLABELLED: In time, well water, as a source of drinking and coking water, with physical-chemical, bacteriological, and biological indicators suggestive of alteration in water potability, determines complex, sometimes irreversible, metabolic disorders. MATERIAL AND METHODS: Sixty individuals residing in a rural community were divided into 2 groups: study group -30 subjects using well water, and control group--30 subjects using safe water. For the study group the selection criteria were: age, sex, use of well water as drinking and cooking water, history suggestive of chronic poisoning (pregnancy course, birth weight, susceptibility to infectious agents, and current chronic diseases). RESULTS: In the study group, gestosis, prematurity, and altered body mass index are more frequent as compared to the subjects in the control group. The identified laboratory changes indicate moderate anemia, hepatic cytolysis, dyslipidemia, presence of nitrites in urine, and positive urine cultures. CONCLUSIONS: Long-term use of water with mineral constituents in excess, absent, or inadequate, the direct biological and chemical water pollution, or most frequently the indirect pollution through the soil determine, in time, complex, sometimes irreversible, metabolic disorders.