International Journal of Hygiene and Environmental Health
ReviewEffects of sanitation on cognitive development and school absence: A systematic review
Introduction
Almost one billion people currently lack access to sanitation (UNICEF, 2015). Most live in rural settings in developing countries and practice open defecation. Systematic reviews on the health impacts of sanitation have focused on anthropometric outcomes (Dangour et al., 2013; Freeman et al., submitted) or on infectious disease outcomes, such as diarrhoea, trachoma, soil transmitted helminth infection and schistosomiasis (Clasen et al., 2010; Freeman et al., submitted; Grimes et al., 2014, Stocks et al., 2014, Strunz et al., 2014, Wolf et al., 2014). The World Health Organization (WHO), however, defines health not only as the absence of disease but as a “state of complete physical, mental and social well-being.” Sanitation has the potential to address not only infectious disease but various aspects of well-being, such as reaching one’s full potential through proper cognitive development and the ability to attend school and work.
Researchers have begun to explore the different causal pathways for these learning outcomes. In one pathway, researchers theorize and initial studies show that access to sanitation lowers rates of sanitation-related illnesses and as a result, may lead to better cognitive ability and a healthier state to attend school or work (Khalil et al., 2016, Pinkerton et al., 2016, Watanabe and Petri, 2016) (Fig. 1–A). Even reductions in asymptomatic but repeated enteric infections, known as environmental enteropathy, has been linked to improvements in early childhood development (Kosek, 2017). In another pathway specific to the school setting, access to adequate school sanitation creates a comfortable learning environment which may lower rates of student absence and ultimately lead to better school performance (Pearson and McPhedran, 2008) (Fig. 1–B). Several studies in low and middle-income countries have also explored the connection between adequate school sanitation and attendance rates of postmenarcheal girls who require sanitation facilities to hygienically and comfortably manage their menstruation (Boosey et al., 2014, Haver et al., 2013, Long et al., 2013, Pearson and McPhedran, 2008, Phillips-Howard et al., 2016, Sommer, 2010). The purpose of this review is to assess the impact of sanitation, be it access, quality or a specific sanitation intervention at the household, school or community level, on cognitive development and absence from school or work.
The WHO commissioned this systematic review as part of its effort to develop the evidence base for a set of guidelines on sanitation and health. This review is one of three reviews on the impact of sanitation on different health outcomes: sanitation-related infectious diseases and nutritional status (Freeman et al., submitted), wellbeing (Sclar et al., unpublished results), and the current two outcomes of interest − cognitive development and absence from school or work. Since only two eligible studies examined both school and work absence, we describe cognitive development and absence as ‘learning outcomes’ throughout this review. In addition, although the literature to date often uses the term “absenteeism” to describe this learning outcome, “absenteeism” specifically refers to missing school or work on a regular basis and often without a suitable reason like illness. As such, we use the term “absence” which more generally refers to the act of missing school or work. These reviews on sanitation and aspects of health are part of a series of systematic reviews that also examine the impact of different sanitation interventions on latrine coverage and use (Garn et al., 2016) and the impact of sanitation on transmission pathways (Sclar et al., 2016a).
Section snippets
Search strategy
We searched the literature to identify relevant studies that address the impact of sanitation on measures of cognitive development and absence (see Supplemental Text S1 for protocol and Supplemental Text S2 for PRISMA Checklist). Our search included studies published in English, Spanish, Portuguese, French, German or Italian with any publication status (published, unpublished, in press, grey literature, etc.) written between 1950 and December 2015. We conducted our search in English and used
Search results
Execution of the search strategy yielded 10,013 titles and abstracts. After screening, two reviewers examined the full text of 528 studies for further assessment. Of these, 17 studies met the review’s eligibility criteria (Fig. 2). Four of these studies reported only on measures of children’s cognitive development (Table 2), 12 reported on children’s school absence (Table 3), and one study reported on both. The majority of eligible studies (N = 11) were published in the last five years,
Discussion
Sanitation has the potential to impact many aspects of health. Among the possible effects of improved sanitation at home or in the school setting, are improvements in cognitive development and school attendance. The former is hypothesized as an indirect effect of reduced insults from pathogenic agents, especially in regards to environmental enteropathy (Khalil et al., 2016, Kosek, 2017, Pinkerton et al., 2016, Watanabe and Petri, 2016), while the latter are believed to be drawn both from
Acknowledgements
We are grateful to Darcy Anderson, Henrietta Lewis, Amrita Mahtani, Divya Narayanan, and Rachel Stelmach for their work on the title, abstract, and full text review. We are also grateful to Darcy Anderson and Amrita Mahtani for their assistance on data extraction and the risk of bias assessments. Finally, we would like to acknowledge funding support for this review from the World Health Organization.
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