A further randomized evaluation studied WSP’s
Total Sanitation and Sanitation Marketing program in rural East Java, Indonesia.23 Like the findings in the other field experiments, the effect on open defecation was found to be small: the program was claimed to have caused an approximately 2 percent- age point decline in open defecation overall, and a 5.8 percentage point decline among participants without sanitation facilities before the experiment. With such a small effect on sanitation, the experi- menters could find improvements in child weight and height only among nonpoor households without sanitation at baseline, but not in the full sample.
The Difficulty of Estimating the Effect of
Sanitation on Child Height from an Experiment Researchers and policymakers oſten talk about “the” effect of an input or an intervention, such as the effect of open defecation on child height. Yet effects are, in fact, different in different contexts. Tis varia- tion across places, programs, and populations means that the set of effect sizes available from experimen- tal evidence will always be shaped by the contexts in which experiments can and do happen. One important recent review surveyed impact
evaluations of WASH interventions, focusing on the effects on child nutritional outcomes.24 By design, the review excluded both population-level obser- vational studies and indeed any research that did not study an intervention. Terefore, its view of the effects of WASH on child height was shaped by the interventions studied in the literature, and by the ability of those interventions to change WASH behaviors. Te review identified 14 eligible studies, including interventions targeting solar disinfection of drinking water and hand hygiene. Yet the only studies pooled in a meta-analysis were the five stud- ies that were randomized. Te reviewers concluded that the studies collectively are suggestive of a ben- efit of these WASH interventions for child height, although they also cautioned the reader regarding the methodological quality of the reviewed studies. Te ability of intervention studies to illuminate
the effect of sanitation on child height (stage 2 in Figure 1) will always depend upon the ability of available interventions to change sanitation behav- ior (stage 1 in Figure 1). For an extreme example, it
22 WHY SANITATION MATTERS FOR NUTRITION
would clearly not be possible to learn about the effect of open defecation on child height from an interven- tion that does not reduce open defecation at all. Tis is a mater of practical concern: we have seen several examples of large-scale intervention studies that achieved only very small improvements in sanita- tion behavior. Because 60 percent of the people worldwide who
defecate in the open live in India, it is perhaps the context where understanding the effect of sanitation on nutrition would be most relevant. A recent survey of rural households in five north Indian states high- lights a deep-seated, socially embedded aversion to latrine use.25 Many people in rural north India believe that open defecation is part of a wholesome rural way of life. Perhaps more important, latrine use is discouraged by social notions of purity and pollution. As a result, many people living in house- holds with working latrines do not use them, even in instances where another family member does. In a special challenge for sanitation policy, most people who live in a household with a government con- structed latrine still defecate in the open. Tere is every reason to expect that the effect of
sanitation improvements on nutritional outcomes is not the same worldwide. For example, studies suggest that the effect on neighbors’ health of moving from open defecation to latrine use might be greater than the effect of moving from simple latrines to beter toi- lets.26 We have seen evidence that population density interacts with sanitation to shape child health: open defecation seems to mater more where people live more closely together. All of these factors suggest that the effect of sanitation on child height may be espe- cially large in densely populated India, where resis- tance to sanitation behavior change is strong.
PRIORITIES FOR RESEARCH
Te initial priority is to address first-stage problems by improving the programmatic and policy tools available to change sanitation behavior. Indeed, even if we were not concerned with improving inter- vention studies of the nutritional consequences of WASH, learning how to be more effective at chang- ing open defecation behavior into latrine use, par- ticularly in India, would be a top priority for further
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