The Evidence Base for Cognitive, Nutrition, and Other Benefits From Water, Sanitation, and Hygiene Interventions

Cost-benefit analysis of WASH (water, sanitation, and hygiene) interventions have traditionally focused on two primary benefits: improved health outcomes, usually measured as reduced diarrheal disease incidence, and reduced time burdens from collecting water, treating water, or traveling to open defecation or shared sanitation sites. However, there are also many other important benefits of water, sanitation, and hygiene interventions for policymakers and researchers to consider, such as improved nutrition and decreased stunting, improved cognitive development and educational attainment, and quality-of-life improvements for women. Reduced fecal exposure from improved WASH may decrease not only diarrheal disease incidence but also the risk of environmental enteropathy, a condition that reduces the nutritional absorptive capacity of the gut. Environmental enteropathy results in a range of outcomes associated with malnutrition, such as wasting, stunting, and anemia. A growing body of literature has explored the direct relationship between improved sanitation environments and stunting. There are mixed findings from these research studies, suggesting that intervention adherence and baseline sanitation conditions may be important to realizing any potential stunting benefits. The economics literature has documented a strong inverse relationship between childhood stunting and lifetime earnings. Reduced absorptive capacity from environmental enteropathy may also hinder cognitive development in children. Recent research documents a strong relationship between improved sanitation environments and cognitive development in children, though some studies find no relationship. Beyond cognition, improved health from reduced fecal exposure may also affect a child’s ability to attend school, and research shows a relationship between WASH environments and school attendance and enrollment. Monetizing the benefits of improved schooling in a low-income country context is challenging due to high variation in school quality as well as high rates of self-employment. Quality-of-life benefits for women are a third category of benefits that are often omitted from WASH cost–benefit analyses. Mostly qualitative research highlights that poor sanitation and water insecurity is associated with safety, security, privacy, and dignity concerns for women. While these concerns and experiences are difficult to quantify in many cases, they should not be ignored when considering WASH benefits.