After about a century and half, the importance of safe water, sanitation and hygiene (WASH) was realized, acknowledged and supported by the availability of increasing body of evidence. WASH interventions proved beneficial in combating diarrhea, while having a considerable impact on nutrition, complementary food hygiene, school attendance, oral vaccine performance and elimination of neglected tropical diseases [4,5]. WASH interventions have had a reasonable and cumulative effect on child growth in multiple ways. Half of the under-nourishment in the world is a result of factors such as no access to clean water and sanitation, and poor hygiene practices. WASH interventions are cost-effective as well. For every US$ invested in sanitation, the return on investment is US$ 5.50 with lower health costs, more productivity and fewer preterm births [6]. In 1990s, unsafe water, unsafe sanitation and improper handwashing were the second, seventh and ninth major risk factors for diseases, respectively. Things have improved in last two and half decades with scale-up of WASH interventions. By the end of 2015, their ranking has fallen to fourteenth, nineteenth and eighteenth, respectively [7]. In India, the WASH risk factors were the second biggest (~13% of attributable burden) contributors to diseases in 1990, which were brought down to seventh (with 4.6% attributable burden) by 2015 [8].

Despite the progress, the WASH risk factors continue to be the leading causes of health inequities amongst the women and children while having a considerable effect on other vulnerable populations in low- and middle-income countries (LMICs) [6]. The United Nations General Assembly (UNGA) in 2010 had explicitly recognized the human right to water and sanitation [9]. In this background, it is no surprise that the need for safe water was given its due place, earlier in the Millennium Development Goals (MDGs) and now, in the Sustainable Development Goals (SDGs). While the SDG-6 focuses on water and sanitation, the target 6.1 mentions – "By 2030, achieve universal and equitable access to safe and affordable drinking water for all." The target 6.2 says that "By 2030, achieve access to adequate and equitable sanitation and hygiene for all, end open defecation and pay special attention to the needs of women and girls and those in vulnerable situations." The achievement of SDG-6 and related targets would contribute to achieve most of the other sixteen SDGs [10].

This issue of Indian Pediatrics carries a systematic review on the effects of WASH interventions on growth, non-diarrheal morbidity and mortality in children residing in LMICs [11]. The authors analyze evidence on the effect of WASH interventions on non-diarrheal morbidity and mortality, and report little or no effect on the anthropometric indices in LMICs. In the end, the authors support the ongoing provision of WASH interventions. As this review [11] has reported the quality of evidence to be from ‘low to very low’ for most of the studies, one might be tempted to suggest the need for methodological rigor for studies, including Randomized Controlled Trials (RCTs), specifically for WASH interventions. However, in the research studies and RCTs on WASH interventions, one may face logistical challenges of randomization, which precludes evidence generation and reduces the quality of evidence. There are logical and ethical arguments against the use of ‘death from diarrhea’ as the principle health outcome of interest. The alternative outcomes, particularly self-reported diarrhea morbidity, have proven validity. A lot of evidence in this field is based upon consensus and plausibility of WASH interventions contributing to a number of additional benefits. A parallel challenge in LMICs is failure to introduce and scale-up of public health interventions with sufficient evidence and proven cost effectiveness. The setting-specific evidence that can stand all scrutiny is not always available and feasible. Conducting such studies requires a large sample size, long follow-up, and a lot of financial resources, which is not always possible in LMICs. Research would prove an important tool in achieving universal health coverage and SDGs [12]. The untiring desire to generate additional scientific evidence contributes to the advancement of medical science and public health. However, scientific community is also mindful of the fact that no randomized control trials have been conducted to check the effectiveness of parachute in gravitational challenges and injury prevention [13]. In public health, there is ample evidence (on many aspects) concerning the scaling-up of interventions. The situation demands convergence between academicians and the policy makers/program managers to ensure that introduction and scaling-up of interventions is not unnecessarily delayed for want of additional and impeccable evidence [12,14]. The additional studies on benefits of WASH interventions would contribute to a pool of scientific evidence; however, the immediate programmatic relevance and utility of all new findings might remain arguable.

Disclaimer: Author is a staff member of the World Health Organization (WHO). The views expressed in this editorial are personal and do not necessarily represent the decisions, policy, or views of WHO.

Funding: None; Competing interests: None stated.

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