The Impact of Water, Sanitation and Hygiene on Key Health and Social Outcomes: Review of Evidence, June 2016

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Executive summary

This evidence paper looks at 10 areas identified collaboratively with the United Nations Children’s Fund (UNICEF) on which WASH can plausibly have a strong impact: diarrhoea, nutrition, complementary food hygiene, female psychosocial stress, violence, maternal and newborn health, menstrual hygiene management, school attendance, oral vaccine performance, and neglected tropical diseases. Together, these areas cover the most significant sector outcomes associated with the distinct life course phases1 that UNICEF seeks to help to address through its WASH activities.
UNICEF’s strategic vision on WASH is to achieve universal and sustainable water and sanitation services and the promotion of hygiene, with a focus on reducing inequalities especially for the most vulnerable children, wherever they are; both in times of stability and crisis.

The paper highlights a number of points where evidence-based consensus has been established, or is emerging in these areas, and these are summarized here:

  1. Despite discussion in recent years around the best approach for estimating the proportion of the diarrhoeal disease burden attributable to poor WASH, there is strong consensus that that the majority of this disease burden is due to poor WASH;

  2. WASH plausibly influences child growth in multiple ways.
    While the magnitude of effect for WASH interventions on undernutrition is less clear, there is a strong and growing consensus, in both the WASH and nutrition sectors, that WASH is an essential component of strategies to reduce undernutrition, and that efforts should be concentrated on the first 1000 days— from conception to a child’s second birthday;

  3. Inadequate food hygiene practices can lead to high levels of microbial contamination of food, and interventions focusing on critical control points may reduce this contamination. While we need to better understand how to change behaviour sustainably through such interventions, and to assess their impacts on child health, there is growing consensus on the importance of integrating food hygiene components into both WASH and nutrition programmes;

  4. Although the evidence base remains largely qualitative in nature, it is increasingly accepted that inadequate access to WASH can expose vulnerable groups—particularly women and girls—directly to violence. This may cause psychosocial stress due to the perceived threat of such violence, adding to other causes of psychosocial stress such as the perceived threat of harassment, or the threat of being unable to meet basic needs;

  5. WASH plausibly affects maternal and newborn health through multiple direct and indirect mechanisms, and WASH coverage in delivery settings in low and middle-income countries is extremely low. There is a consensus that safe WASH in health facilities—and in other delivery settings—is critical for accelerated progress on maternal and newborn health;

  6. Further rigorous research is needed on the impact of poor MHM on social and health outcomes, but the challenges and barriers associated with MHM among schoolgirls and women are well documented through qualitative studies. Few would contest that a girl or woman without access to water, soap, and a toilet, whether at home, school, or work, will face great difficulties in managing her menstrual hygiene effectively and with dignity. Furthermore, there is consensus on what is required to enable safe, dignified management of menstrual hygiene: knowledge, materials and facilities;

  7. In many countries, it has been reported that poor WASH facilities act as a barrier to student attendance and enrolment. This affects girls in particular, but especially girls postmenarche, when their MHM needs may not be addressed. Until recently, there was little robust evidence to support this but there has now been a least one rigorous intervention study supporting the positive effect of improved WASH on school attendance—for both boys and girls—when services are well designed and managed. In addition, there is a growing body of evidence around successful approaches to increasing access to WASH in schools;

  8. While the evidence for the impact of WASH on oral vaccine performance is only suggestive and further research is needed to demonstrate its effect, there is a recognition that routine immunization campaigns may be a useful entry point for promoting safe hygiene among caregivers;

  9. While investments to address NTDs remain largely focused on treatment measures such as mass drug administration (MDA) campaigns, there is strong consensus, supported by good evidence, that WASH plays an important role in preventing the transmission of these diseases;

  10. The distribution of WASH-related mortality and morbidity is inequitable, and falls disproportionately on the poor, on women and on children. There is a clear consensus that for WASH policy and programmes to be effective, they must address this inequality