4
Addressing Risk for Waterborne Disease

OVERVIEW

Contributors to this chapter discuss a broad range of responses to the threat of waterborne disease, including drinking water disinfection, increasing access to water, improving sanitation, and investment in and implementation of public health interventions. Among these, the most seemingly straightforward approach—water treatment—is actually far from simple, as Philip Singer, of the University of North Carolina at Chapel Hill, demonstrates in the chapter’s first paper. Singer provides a quantitative overview of water quality and disinfection, emphasizing the use of chlorine as a disinfectant. He describes water quality factors (e.g., reduced inorganic material, dissolved organic carbon, and microbial contents) that influence chlorine’s effectiveness, and explains how sanitary engineers use the concept of “chlorine demand” to assess and address these factors in order to achieve water disinfection with chlorine. He also discusses parameters and limitations of various approaches to water treatment, including solar radiation, giving special attention to the significant barrier to disinfection posed by particulate matter and its removal by various filtration and flocculation methods.

In the developing world, the profound disease burden attributed to diarrhea makes it the most important target for waterborne disease prevention, according to workshop speaker Thomas Clasen of the London School of Hygiene and Tropical Medicine. Following a systematic review of interventions to improve water quality for preventing diarrheal disease (Clasen et al., 2007a), which compared interventions at the both the source (protected wells, bore holes, and distribution to public standpipes) and in the household (improved water storage, solar disinfection, filtration, and combined flocculation-disinfection), he and



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4 Addressing Risk for Waterborne Disease OVERVIEW Contributors to this chapter discuss a broad range of responses to the threat of waterborne disease, including drinking water disinfection, increasing access to water, improving sanitation, and investment in and implementation of public health interventions. Among these, the most seemingly straightforward approach—water treatment—is actually far from simple, as Philip Singer, of the University of North Carolina at Chapel Hill, demonstrates in the chapter’s first paper. Singer provides a quantitative overview of water quality and disinfection, emphasizing the use of chlorine as a disinfectant. He describes water quality factors (e.g., reduced inorganic material, dissolved organic carbon, and microbial contents) that influence chlorine’s effectiveness, and explains how sanitary engineers use the concept of “chlorine demand” to assess and address these factors in order to achieve water disinfection with chlorine. He also discusses parameters and limita- tions of various approaches to water treatment, including solar radiation, giving special attention to the significant barrier to disinfection posed by particulate matter and its removal by various filtration and flocculation methods. In the developing world, the profound disease burden attributed to diarrhea makes it the most important target for waterborne disease prevention, accord- ing to workshop speaker Thomas Clasen of the London School of Hygiene and Tropical Medicine. Following a systematic review of interventions to improve water quality for preventing diarrheal disease (Clasen et al., 2007a), which com- pared interventions at the both the source (protected wells, bore holes, and distribution to public standpipes) and in the household (improved water storage, solar disinfection, filtration, and combined flocculation-disinfection), he and 200

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20 ADDRESSING RISK FOR WATERBORNE DISEASE coauthors concluded that household-based interventions were nearly twice as effective as source-based measures. Clasen and coworkers subsequently con- ducted a cost-effectiveness analysis to determine the cost per disability-adjusted life year (DALY, a measure of disease burden) averted for a similar range of source and household interventions (Clasen et al., 2007b). The researchers found that upon reaching 50 percent of a country’s population, interventions involving household chlorination and solar disinfection paid for themselves and that all inter- ventions were cost-effective. The most prevalent method of home water treatment worldwide, boiling, was not included in these analyses. Although highly effective in reducing microbiological contamination, boiled water can be readily recontaminated; moreover, Clasen noted, boiling is relatively costly, is associated with risk for burn accidents, and results in indoor air pollution as well as carbon emissions (Clasen, 2008). Because of boiling’s prominence, Clasen’s group has conducted assessments of its microbiological effectiveness and cost in several developing country settings in order to establish a benchmark against which other safe drinking water interventions can be compared. For example, in a recent study in semirural India, where more than 10 percent of households disinfect their drinking water by boiling, the researchers found that boiling, as practiced in these communities, significantly improves the microbiological quality of water (on a par with water filters), but does not fully remove the potential risk of waterborne pathogens (Clasen et al., 2008). They also calculated that while the entry costs of boiling are the least of any water treatment option in this setting, the cost of continuing the practice annually is greater than the ongoing out-of- pocket cost of treating the same volume of water with sodium hypochlorite, or solar disinfection, and the five-year cost of boiling would also exceed most filtration options. Efforts to increase the availability, uptake, and correct, consistent use of household water treatment and safe storage systems are spearheaded by the Inter- national Network to Promote Household Water and Safe Storage, a consortium of interested UN agencies, bilateral development agencies, international non- governmental organizations (NGOs), research institutions, international profes- sional associations, and private sector and industry associations (Clasen, 2008; WHO, 2008). The Network now claims more than 100 members from govern- ment, UN agencies, international organizations, research institutions, NGOs, and the private sector and has accomplished much in terms of advocacy, communi- cation, research, and implementation. However, despite these achievements, the mission of the Network to “achieve a significant reduction of waterborne disease, especially among children and the poor” is far from realization. Presently, only a tiny fraction of the millions of people who could benefit from household water treatment and safe storage (HWTS) interventions—far more than the one billion who use “unimproved” water sources, as previously noted—are being served, and those who need them most are the most difficult to reach.

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202 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH In a recent report authored for the World Health Organization (WHO), Clasen (2008) examined efforts to scale up other important household-based interventions (e.g., oral rehydration salts, treated mosquito nets) for lessons of potential value to scaling up HWTS. He found several important recurring themes applicable to scaling up HWTS. These include the need to • focus on the user’s attitudes and aspirations; • take advantage of simple technologies (minimize behavior change); • promote nonhealth benefits, such as cost savings, convenience, and aesthetic appeal; • use schools, clinics, and women’s groups to gain access to more vulner- able population segments; • take advantage of existing manufacturers and supply channels to extend coverage; • provide performance-based financial incentives to drive distribution; • align international support and cooperation to encourage large-scale donor funding; • use free distribution to achieve rapid scale-up and improve equity; • use targeted subsidies, where possible, to leverage donor funding; and • encourage internationally-accepted standards to ensure product quality. In his workshop presentation, Clasen noted that all introductions of novel health interventions to low-income populations face similar challenges—creating awareness, securing acceptance, ensuring access and affordability, establishing political commitment, addressing sustainability—but several additional barriers exist that must be overcome to scale up HWTS. These include • the widely held belief that diarrhea is not a disease; is • skepticism about the effectiveness of water quality interventions; • technology shortcomings with the available interventions; • need for correct, consistent, sustained use (as compared with one-time interventions, such as vaccines); • the existence of several transmission pathways for waterborne disease; • suspicion on the part of the public health sector regarding the commercial agenda and lack of standards governing HWTS products; • the orphan status of HWTS within governmental ministries; and • the lack of focused international commitment and funding for diarrheal diseases. “The goal of scaling up HWTS will not be achieved simply by putting more resources into existing programmes or transitioning current pilot projects to scale,” Clasen (2008) concludes.

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203 ADDRESSING RISK FOR WATERBORNE DISEASE The gap between where we are and where we need to be is to great given the urgency of the need. What is needed is a breakthrough. The largely pub- lic health orientation that has brought HWTS to its present point now need to enlist the help of another group of experts: consumer researchers, product designers, educators, social entrepreneurs, micro-financiers, business strategists and policy advocates. The private sector is an obvious partner; they not only possess much of this expertise but also the incentive and resources to develop the products, campaigns and delivery models for creating and meeting demand on a large scale. At the same time, market-driven, cost-recovery models are not likely to reach vast populations at the bottom of the economic pyramid where the disease burden associated with unsafe drinking water is heaviest . . . mass coverage among the most vulnerable populations may be impossible without free or heavily subsidized distribution. For this population segment, the public sector, UN organizations and NGOs who have special access to these popula- tion segments must engage donors to provide the necessary funding and then demonstrate their capacity to achieve both scale and uptake. Governments and international organizations can also help encourage responsible action by the private sector by implementing performance and safety standards and certifica- tion for HWTS products; reducing barriers to importation, production and dis- tribution of proven products; and providing incentives for reaching marginalized populations. (Clasen, 2008) Many of the ideas raised by Clasen regarding appropriately scaled water and sanitation infrastructure for developing countries are expanded upon by work- shop speaker Joseph Hughes and coauthors, who offer an engineer’s perspective on water infrastructure in the developing world in the chapter’s second paper. Caravati et al. envision a new model for water and sanitation infrastructure that addresses global complexities, rather than a “one size fits all” approach based on developed-world systems. The authors describe several promising technologies that may help to address water and sanitation challenges in developing coun- tries. First, however, they provide comprehensive background information on the dynamics of natural water movement, as well as the passage of water through the “engineered hydrologic cycle” of water and wastewater collection, treatment, and distribution. Conventional, developed-world water and sanitation technologies “are often chemical-, energy- and operational-intensive, are based on heavy infrastructure systems (i.e., dams, pumps, distribution grids, etc.), and require considerable capital and maintenance, all of which hinder their use in much of the world,” the authors note. “If safe water and appropriate sanitation are to become accessible to those who are not currently served, new approaches and modern technologies must be employed. This will require a significant change in the way water and wastewater treatment systems are conceived and how they interact with other infrastructures systems (i.e., energy).” They outline a “new paradigm” for water and sanitation infrastructure and describe how progress under way in three vital

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20 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH areas—increased energy efficiency, availability of capital for business creation, and technology development—can advance this paradigm. Their contribution concludes with a review of research needed to fully develop a new, globally- appropriate model for water and sanitation infrastructure. Given the global trend toward urbanization, particular attention must be paid to water and sanitation challenges for humans—tens of millions of them in megacities—living in close proximity to each other. The chapter’s third contribu- tion, by workshop speaker Pete Kolsky of the World Bank and coauthors Kristof Bostoen and Caroline Hunt, focuses on the complex relationships that must be understood in order to recognize and address the threat of waterborne disease in urban settings, particularly in low-income communities. This essay originally appeared as a chapter in the book Scaling Urban Environmental Challenges: From Local to Global and Back (Marcotullio and McGranahan, 2007). Bostoen et al. begin by reviewing the effects of water supply, sanitation, and hygiene on health as viewed through two common models that clarify the complex interrelationships among these elements: classifications of water- related infections (see also Bradley in Chapter 1) and the F-diagram (depicted in Figure WO-13), a model of fecal-oral disease transmission. They then examine goals set by the international community for water and sanitation, along with obstacles that must be overcome in order to meet these goals, including the need to develop reliable measures of progress toward these goals. Following an examination of the significance of boundaries—“limits beyond which and indi- vidual or group feels no responsibility”—to urban water and sanitation issues, the authors conclude that institutional boundaries (which are central to many enviromental problems) must be identified and acknowledged. Improvements in water and sanitation services are significant only if they lead to change at the household level, they contend; therefore, household access to these services must be monitored and evaluated. Ultimately, the threat of waterborne disease must be addressed through investment in safe water and sanitation interventions. Such investments are dras- tically underfunded, according to workshop speaker Vahid Alavian of the World Bank, who noted that the annual investment in water and sanitation needed to meet the MDGs exceeds $25 billion; only about half that sum is currently being spent. The World Bank is the largest global investor in water/sanitation investment, he added, but its portfolio of about $11 billion cannot begin to meet demand. His colleague Kolsky pointed out that the World Bank’s water and sanitation program at the Bank has received a grant of $20 million from the Bill and Melinda Gates Foundation to support sanitation scale-up and hygiene promotion projects, of which a significant fraction (15 to 20 percent) will be spent to evaluate the effectiveness of scaled-up interventions. The chapter’s final essay, by speaker Sharon Hrynkow of the National Insti- tute of Environmental Health Sciences (NIEHS) introduces a potential engine to drive the improvement of water quality and access in low-income settings: the

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20 ADDRESSING RISK FOR WATERBORNE DISEASE phenomenon of social entrepreneurship. Using illustrative examples, she con - trasts the social entrepreneur’s approach to solving these problems by focusing on delivering interventions or gathering information for policy purposes with that of medical researchers, who attempt to identify connections between toxins or microbes and illness, and then to reduce human exposure to disease agents. “Increasing the dialogue between the medical research community and the social entrepreneur community would likely enhance operations on both sides,” Hrynkow concludes. In particular, she envisions an alternative to traditional medical grants, which rarely support policy development, that could support both medical research and social entrepreneurship and thereby encourage the transition of solutions for safe water and sanitation from basic science into practice. MEASURES OF WATER QUALITY IMPACTING DISINFECTION Philip C. Singer, Ph.D.1 University of North Carolina at Chapel Hill This paper provides a discussion of important water quality factors impacting disinfection, with an emphasis on the use of chlorine as a disinfectant. It has been prepared to be somewhat tutorial in nature in an attempt to educate those unfamiliar with the complexities of water disinfection by chlorine. There are numerous text- books with chapters on this subject (Letterman, 1999; MWH, 2005). Drinking Water Disinfectants Several different types of disinfectants are used to treat drinking water: free chlorine (HOCl/OCl–) • • combined chlorine (i.e., monochloramine [NH2Cl]) • ozone (O3) • chlorine dioxide (ClO2) • ultraviolet (UV) irradiation When chlorine is added to water, it hydrolyzes to form hypochlorous acid (HOCl) and the hypochlorite ion (OCl–). Hence, free chlorine in water is a com- bination of HOCl and OCl–. Chlorine is the most widely used disinfectant for the purification of drinking water in the world. Ozone and chlorine dioxide are also used to disinfect drinking water in the United States, western Europe, and in some of the advanced Pacific Rim nations, but not in the developing world. UV 1 DanOkun Distinguished Professor of Environmental Engineering, Department of Environmental Sciences and Engineering, Gillings School of Global Public Health.

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20 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH irradiation—including simple solar irradiation methods employed in the develop- ing world—is a growing technology to disinfect drinking water. Disinfection Kinetics Free chlorine is an effective disinfectant for inactivating waterborne bacteria, viruses, and a variety of protozoan cysts (e.g., Giardia), but it is not effective against Cryptosporidium. Its effectiveness for inactivating microorganisms can be quantified under various conditions by a measure known as CT.2 CT values are derived from the CT term in the Chick-Watson expression dN/dT = –kCN (1) in which N is the number concentration of microorganisms, k is a rate constant, C is the concentration of the disinfectant, and T is time. Integration of Equa- tion (1) yields the log of inactivation as a function of the concentration of dis- infectant multiplied by the contact time, expressed in units of milligram-minutes per liter. Log10 No/N = kCT/2.3 (2) The rate constant, k, depends on the specific disinfectant, the type of organism, and temperature. No is the initial concentration of organisms. Requisite CT values to achieve various degrees of inactivation are temperature-dependent. Table 4-1 shows CT values for the inactivation of Giardia and viruses by chlorine over a range of temperatures. In water at 5°C, at a concentration of 1 milligram per liter (mg/L) of chlorine, it will take 149 minutes to achieve 3-log inactivation of Giardia. For colder waters, more chlorine and/or longer contact times are needed to achieve the same degree of inactivation. Table 4-1 also shows that the CT values for virus inactivation are smaller than those for Giardia, reflecting the fact that viruses are easier to inactivate with chlorine than Giardia. At residual chlorine levels of 0.2 to 0.3 mg/L under the same conditions, 3-log inactivation of Giardia will require on the order of 12.5 hours (not shown). Factors Affecting Disinfection with Chlorine pH Several factors, in addition to temperature, influence the disinfectant potency of chlorine. The pH is an important consideration because it determines the form of chlorine present (HOCl or OCl–). Hypochlorous acid is a more potent disinfec- 2 CT = product of free chlorine residual (C) and contact time (T) required for disinfection.

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20 ADDRESSING RISK FOR WATERBORNE DISEASE TABLE 4-1 CT Values (mg-min/L) for Microbial Inactivation by Free Chlorine (pH 7.0, 1.0 mg/L Cl2 residual) Temperature (oC) < = 0.5 5 10 15 20 25 4-log virus inactivation 12 8.0 6.0 4.0 3.0 2.0 3-log Giardia inactivation 210 149 112 75 56 37 SOURCE: Based on data in AWWA (2006). tant than the hypochlorite ion; therefore, disinfection tends to be more effective with decreasing pH. Chlorine Demand/Reducing Agents Because chlorine is also a good oxidant, its stability in water is influenced by the presence of reduced inorganic and organic materials in the water, which exert a chlorine demand and chemically reduce the chlorine concentration. Addition- ally, the type and state of the microbial agents (i.e., whether the organisms occur as single cells or are associated with particles suspended in the water) affect the ability of chlorine to disinfect the water. All of these factors determine the dose of chlorine that must be applied to a given water so that the target residual chlorine concentration (C) remaining at the end of a given contact time (T) can be achieved in order to meet the requisite CT value to ensure the desired degree of inactivation. The dose of chlorine applied, minus the chlorine residual, is known as the “chlorine demand” associated with a particular water supply. In a municipal water treatment facility, chlorine is usually applied to the raw water at the head of the treatment plant or after sedimentation or filtration, and the residual is measured at the point of entry to the distribution system. The difference between the dose and the residual is the chlorine demand and is due to consumption of chlorine by reduced organic and inorganic sub- stances in the water. The higher the concentration of reduced organic or inorganic material, the greater the requisite chlorine dose needed to achieve a target residual and, hence, the greater the chlorine demand. In a village in which a woman col- lects water and carries it to her home where she adds chlorine to it, the chlorine demand reflects the amount of chlorine that must be added to the water in the container in order achieve the desired degree of inactivation in a specified time period, after which the water is presumed to be safe to drink. To achieve the desired residual chlorine concentration to meet a target degree of inactivation as characterized by CT, one needs to calculate the dose of chlo- rine that must be added to any given water. To do this properly, one needs to know the degree to which reduced substances present in the water can lower the concentration of chlorine. This relationship is depicted in Figure 4-1, which compares chlorine dose and residual free chlorine concentrations for several raw

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20 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH 4 1%, 15mL/L 2%, 10mL/L 2%, 15mL/L 3 Free chlorine residual (mg/L) 2%, 20mL/L 5%, 15mL/L 2 MIEX effluents 1 Raw waters 0 0 1 2 3 4 5 6 7 8 Chlorine dose (mg/L) FIGURE 4-1 Chlorine demand of several raw waters and partially treated waters (MIEX® effluents). SOURCE: Reprinted from Boyer and Singer (2006) with permission from Elsevier. and partially treated waters (labeled here as MIEX® effluents). The figure shows that, for the raw waters, 5-6 mg/L of chlorine must be applied in order to achieve a free chlorine residual of 1.0 mg/L. In this figure, the contact time is 24 hours. Figure 4-1 Hence, the chlorine demand of the raw water is 4-5 mg/L. For the treated waters, R01515 because a significant amount of dissolved organic material has been removed by treatment, the chlorine doses needed to achieve the same 1.0 mg/L free chlorine vector, editable residual is 2-3 mg/L, reflecting a chlorine demand of 1-2 mg/L over 24 hours. Hence, in this case, treatment removed approximately 50 percent of the chlorine- demand associated with the dissolved organic material in the raw water. Table 4-2 presents some examples of chlorine-demanding reactions with four inorganic reducing agents commonly found in raw water supplies: reduced (ferrous) iron (Fe(II)), (manganous) manganese (Mn(II)), sulfide (S(–II)), and ammonia (N(–III)). These balanced stoichiometric reactions illustrate the amount of chlorine that must be added to water to overcome the chlorine demand of these reducing agents. Iron, manganese, and sulfide typically derive from natural sources, whereas ammonia is often associated with municipal and agricultural discharges. Drinking water sources contaminated by sewage contain not only fecal bacteria and potentially pathogenic microorganisms but also organic material and ammonia, both of which exert substantial chlorine demands. As shown in

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20 ADDRESSING RISK FOR WATERBORNE DISEASE TABLE 4-2 Chlorine Demand of Various Inorganic Reducing Agents Reaction Chlorine Demand 2Fe2+ + HOCl + 5H2O → 2Fe(OH)3(s) + Cl– + 5H+ 0.64 mg/L of chlorine per mg/L Fe(II) Mn2+ + HOCl + H2O → MnO2(s) + Cl– + 3H+ 0.93 mg/L of chlorine per mg/L Mn(II) H2S + 4HOCl → SO42– + 4Cl– + 6H+ 8.86 mg/L of chlorine per mg/L S(–II) 2NH3 + 3HOCl → N2(g) + 3H+ + 3Cl– + H2O 7.61 mg/L of chlorine per mg/L NH3–N Table 4-2, the chlorine demand associated with ammonia is significant. Figure 4-2 depicts the progression of reactions that occur when increasing amounts of chlo- rine are added to water containing ammonia at a concentration of 0.5 mg/L as N. The first 2.5 mg/L of chlorine is converted to monochloramine; the next 2.5 mg/L of chlorine destroys the monochloramine. After this breakpoint is reached, free chlorine concentrations increase at essentially a 1:1 ratio as more chlorine is added. Thus, in order to get a free chlorine residual (the concentration of free chlorine beyond the breakpoint) necessary to meet the CT requirements for dis- infection in water containing 0.5 mg/L of ammonia, at least 5 mg/L of chlorine must be added. Natural organic material contains aromatic structures, unsaturated double bonds, and organic nitrogen, all of which react with chlorine. In addition to these oxidation reactions, chlorine participates in substitution and addition reac- tions to produce potentially carcinogenic halogenated byproducts. These include trihalomethanes, which are regulated in the United States by the Environmental Protection Agency and elsewhere in accordance with World Health Organization guidelines. On average, 1 to 1.5 mg/L of chlorine is consumed per mg/L of dis- solved organic carbon (DOC) over the course of 24 hours, at pH 8 and 25°C. Raw drinking waters generally contain a combination of chlorine-demanding impurities. A poor-quality surface water, for example, might contain 0.5 mg/L of ammonia and 6 mg/L of dissolved organic carbon, giving a total chlorine demand of 11-14 mg/L (5 mg/L to oxidize the ammonia in accordance with the breakpoint curve in Figure 4-2 and 6 to 9 mg/L for the 6 mg/L of dissolved organic carbon). For a better-quality surface water with 0.2 mg/L ammonia and 2 mg/L DOC, the chlorine demand would be 4-5 mg/L. For groundwater contain- ing 1 mg/L iron, 0.5mg/L manganese, and 1 mg/L DOC, the chlorine demand would be on the order of 2.4 mg/L. Thus, different amounts of chlorine must be added in each case to achieve the same residual free chlorine levels needed for effective disinfection. Measurement of Chlorine Residual The most common method for measuring chlorine residual in treated water, the N,N-diethyl-p-phenylenediamine (DPD) colorimetric/spectrophotometric method,

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20 FIGURE 4-2 Breakpoint chlorination curve when chlorine is added to an ammonia-containing water. SOURCE: Reprinted from Water Chlorination/Chloramination Practices and Principles (M20), with permission. Copyright © 2006 American Water Works Association. Figure 4-2

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2 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH BOX 4-5 Basic and Behavioral Science to Reduce Arsenic Exposures Dr. Joseph Graziano and his colleagues have worked over many years to understand the dose­response relationships between exposure to arsenic and human disease. It is estimated that between 35 and 77 million people are at risk of drinking arsenic­contaminated water in Bangladesh alone (Khan et al., 1997). Over long periods of time, such consumption leads to skin lesions, cancer, and in some cases death. Working in a 25 km2 region in Bangladesh, the Graziano team blends a spec­ trum of disciplines, including environmental health, geochemistry, hydrology, and social science. This interdisciplinary approach grew naturally due to a number of factors, one of which was the startling discovery that tube wells put in place in the 1970s led to unhealthy levels of arsenic in drinking water over much of Bangladesh and South Asia. With accomplishments in lead toxicology already, Dr. Graziano turned attention to the issue of arsenic and manganese in drinking water. Basic research led to discoveries about the cellular mechanisms of toxicity and interventions aimed at reducing impact of arsenic on specific subsets of individuals. In 2000, Graziano and colleagues van Geen and Ahsan expanded their studies to try to understand more fully water usage patterns and preferences for mitigation should local wells be found to exceed accepted limits of arsenic (see Mead, 2005, for overview). With help from local villagers, handheld Global Positioning System devices were used to map the location of each well in an individual village. Later, 12,000 village residents were recruited for a study to determine arsenic levels in urine compared to that found in wells. The team determined that high­arsenic wells and low­arsenic wells could be found in the same village, and the distribution of arsenic in one village did not necessarily correlate with that in the next. This finding suggests that mitigation strategies should be tailored at the subvillage level. More recent work has shown that, even when presented with information on the health impacts of arsenic, other factors come into play in decisions about whether to use water from high­ or low­arsenic wells. Distance to the low­arsenic well appears to be one of the factors involved: if the distance is too far, some will choose to use water from the high­arsenic well over the low­arsenic well. In terms of scale-up and long-term adoption of the interventions, both exam- ples illustrate the challenges in moving from a basic research understanding of a problem to a populations-based intervention strategy. In the case of the folded sari intervention, despite its clear effectiveness in filtering out the cholera vector, and demonstrated reduction in illness after filtering, uptake of the intervention was sustainable in that filtration continued after the project was completed, but the details, namely, the number of folds effective for filtering out the plankton were not adhered to in every case. Similarly, there was a lack of permanent switching to the use of low-arsenic wells. Two challenges present themselves. First, the

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2 ADDRESSING RISK FOR WATERBORNE DISEASE incomplete uptake of the intervention may be due to a lack of local reinforce - ment of the links between clean water and better health within the community. Continued efforts to raise awareness are needed. Second, given the number of donors working in the region, questions may also be raised as to why the simple sari intervention or well-switching interventions were not incorporated into larger development programs. Placing these simple interventions into broader develop- ment perspective bears examination. Discussion The global burden of illness and death directly related to lack of clean water and sanitation demands that we consider all possible strategies. As various groups take on this challenge, new ideas and programs will be put in place. By merging the best features of different approaches, even better strategies may surface. This paper juxtaposes two approaches to improving clean water and sani- tation in resource-poor settings. The social entrepreneur approach focuses on delivery of interventions or gathering of information for policy purposes. The medical research approach focuses on understanding the links between toxins or microbes and attendant ill health, then working to mitigate exposures. Both approaches have yielded immense data sets and new knowledge that has led to improved health. There are similarities and differences between the approaches. Some of the key features of the two approaches are outlined in Table 4-9. Closer examination of two features in particular provide insights into potential future actions. First, how community members were included in the work had an impact on the overall outcomes. The social entrepreneurship model embraces community perspectives as true experts, thereby ensuring that voices heard from the earliest of stages are those from ultimate beneficiaries, and that the work witnesses and subsequently accounts for the incentives faced by those whose social behavior it seeks to change. Interventions based on community involvement had a high degree of uptake. This particular approach leads to feelings of “ownership” of the work, driven by educational or economic incentives, and efforts to ensure its sustain- ability. The medical research model includes important elements of community engagement, particularly during data gathering for pilot efforts and as part of educational efforts related to scale-up of interventions. Long-term sustainability of effective interventions might improve if community engagement were viewed through another lens. Increased community involvement, including consults with local social entrepreneurs, may lead to more effective and long-lasting uptake of interventions, both geographically and on a long-term timescale. One can easily imagine the impact that the folded sari intervention might have in the hands of a social entrepreneur. By the same token, linking information about low- and high- arsenic wells in particular villages to motivated community members or social entrepreneurs might yield new insights on critical operational aspects.

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2 GLOBAL ISSUES IN WATER, SANITATION, AND HEALTH TABLE 4-9 Key Features of the Two Approaches on Clean Water and Sanitation Social Entrepreneurship Medical Research Vision of public health goal from the outset Community viewed as experts and as Community plays a critical role in informing responsible for solving the problem. approaches to scientific project development, in gathering of data, and in education and training related to scale-up. Funding from wherever it can be found, often Funding via government grants, multiple sources single nongovernmental sources, multiple over span of years. sources, or parallel small private enterprises. Science is one of several, equal facets needed Scientific and public health dimensions are to get the job done. Other facets include primary considerations. business, education, social, technology. Each is relevant insofar as it provides incentives for changes in social behavior. Public policy goals may be front and center in Public policy goals to be informed by the guiding the work. outcomes of the scientific efforts. Evaluations important but take place more on Rigorous and regular evaluations required to an ad hoc basis. sustain long-term research support. Second, the type of funding for the two approaches dictates in many ways the range of activities that may be supported. Medical research grants supported by governments tend to limit activities to those that lead to new knowledge about population-based health risks, outcomes due to exposures, including cellular and subcellular responses, and effectiveness of clinical interventions, for example. The development of policy-relevant data has not been a traditional focus of medi- cal research grants. Given the priorities, funding cycles tend to be on the four- to five-year range. The researchers described in the present text pieced together long-term funding strategies over time using multiple sources. This is in contrast to the Ashoka model, which provides support with relatively few conditions for a critical phase of start-up activity intended to lead to population-based policy or intervention results and intended to get the entrepreneurial work to a solid enough footing that more traditional organizations will step in to support and/or replicate. Looking at the two models, it could be speculated that some medical researchers would benefit from a granting system that provided longer term support, perhaps on a 10-year cycle, which included a mid-term review timed to moving basic sci- ence knowledge into practice. Such an approach could capture the best elements of both systems.

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2 ADDRESSING RISK FOR WATERBORNE DISEASE Increasing the dialogue between the medical research community and the social entrepreneur community would likely enhance operations on both sides. Formal and informal means could be identified for exchange of views and exper- tise. Such exchanges might lead to exciting new actions and programs. Possible mechanisms to bolster communication are many and include, first, nominations of social entrepreneurs to public slots on governmental research agency advisory boards and, second, linking social entrepreneurs on the ground with researchers funded through medical research councils or other national or international grant- making bodies. In the latter case, ambassadors, aid mission directors, and other senior government officials, including military, agricultural, and health attachés, could play a role in brokering and facilitating the exchange of ideas between the two communities on the ground. Third, efforts to raise awareness within the medi- cal research community about the social entrepreneurship movement through conferences and lectures would spark ideas for action, particularly from those already attuned to this wave—the next generation. Finally, medical researchers, public health professionals, students, and others should be made aware of new tools such as Changemakers.com, a partnership supported by Ashoka, the Robert Wood Johnson Foundation, and the Global Water Challenge. Through that tool, ideas and entrepreneurial approaches to providing clean water and other seem- ingly intractable problems, including strengthening of health-care systems, have been identified. Encouraging deposits of good ideas and mining the site for good ideas would be useful undertakings. This would in fact be in line with the next- generation vision of Ashoka, “Everyone is a Changemaker.” Acknowledgments I am very grateful to Rita Colwell and Joseph Graziano for allowing me to tell their stories in this context, and also for their generosity in reviewing and editing the draft paper. David Strelneck of Ashoka provided invaluable insights at every step of the way. He and former Ashoka colleague Carol Grodzins reviewed the draft and made extremely helpful suggestions. Appreciation also goes to NIH colleagues Patricia Mabry (OBSSR) and Claudia Thompson (NIEHS) for their guidance and perspectives early on in the framing of this effort. OVERVIEW REFERENCES Clasen, T. F. 2008. Scaling up household water treatment: looking back, seeing forward. Geneva: WHO. Clasen, T. F., W. P. Schmidt, T. Rabie, I. Roberts, and S. Cairncross. 2007a. Interventions to improve water quality for preventing diarrhoea: systematic review and meta-analysis. British Medical Journal 334(7597):782. Clasen, T. F., L. Haller, D. Walker, J. Bartram, and S. Cairncross. 2007b. Cost-effectiveness of water quality interventions for preventing diarrhoeal disease in developing countries. Journal of Water and Health 5(4):599-608.

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