Many scholars from various disciplines presented converging evidence of the key role of open defecation in explaining child stunting in India at a conference at DSE on August 2nd and 3rd.
See slides from conference presentations and more pictures of the conference here.
For two days, leading scholars of child height – economists, epidemiologists, nutritionists, and pediatricians – and government officials including the Honorable Minister of Rural Development Jairam Ramesh met at the Delhi School of Economics to share research on an urgent question: why are children in India so short? Height is an important indicator of overall health and human development because the same things that make a child grow tall are what make a child grow smart. In presentation after presentation of the conference, sanitation stood out as an important part of this puzzle. Unfortunately, India has exceptionally poor sanitation: 60 percent of the open defecation that happens in the world happens in India alone, and almost 50 percent of the Indian population report usually not using a latrine. Not only is open defecation an immense hardship for those who have no other practical option and an important issue of human dignity, the Conference on Sanitation and Stunting also presented an overwhelming convergence in the evidence showing open defecation as a key factor explaining widespread stunting in India.
As Nisha Malhotra, an economist at the University of British Columbia, summarized, “open defecation doesn’t go away” – meaning that there is essentially no way of analyzing data on Indian children’s height where open defecation does not emerge as a key factor explaining shortfalls in child growth. Different research methodologies produced similar conclusions.
Two completed RCTs show a causal effect of sanitation on stunting, others are underway
Two randomized-controlled trials (RCTs) of sanitation interventions, in Maharashtra and Indonesia, show causal evidence of the effect of sanitation and sanitation motivation on increasing child height. Three other RCTs are underway in Orissa, Bangladesh, and Zimbabwe, two of which innovatively examine the effect of sanitation on environmental enteropathy (a disease of the small intestine that prevents nutrients from being absorbed by the body) using biomarkers.
Epidemiological studies show that diseases associated with fecal pathogens increase the odds of stunting
The epidemiological literature also contributes compelling evidence. A Cochrane review of WASH interventions provides suggestive evidence that water quality interventions are effective in reducing stunting. None of the studies exploring sanitation interventions made it through the rigorous protocol for the review, but there are very plausible biological links between sanitation and diarrheal disease, nematode infection, and environmental enteropathy, and other studies by Chekley et al and Humphrey have shown that the odds of stunting increases with these diseases.
Nutritional studies show that open defecation is as important as nutritional intake for child height
Nutritionists at the conference also explored the role of nutrition in child stunting, and their studies showed that nutrition alone cannot explain stunting. A recent Lancet series on nutrition included an analysis showing that if the ten most effective nutrition interventions were scaled up to ninety percent, we would see only a twenty percent reduction in stunting. Maternal and child nutrition are certainly very important for child health, but the research has shown that the combined impact of nutritional interventions and proper sanitation is more effective than either one individually.
International comparisons and within country comparisons over time can explain lots of variation in child height and hemoglobin levels using open defecation alone
Attendees of the conference also heard about studies looking at the link between sanitation and child health outcomes across countries at the population level. An international comparison shows that countries where many people defecate openly are the same countries where the most children are stunted and the average child is shortest. In fact, cross-country differences in sanitation linearly explain 54 percent of the international variation in average child height. Another international comparison shows that countries where many people defecate openly are the same countries where children have the lowest hemoglobin levels, on average. Hemoglobin is an important measure of health because it is a marker of anemia. Biologically, many factors may affect hemoglobin levels, and diarrhea, nematode infections, and environmental enteropathy are some of them. The effects of open defecation in both of these studies do not go away when other variables that may plausibly mediate the relationship are included. Two other studies look at Bangladesh and Cambodia in particular and find that the regions where sanitation improved the most over time were the same regions where child height improved the most over time. As a neighboring South Asian state, Bangladesh’s progress is particularly compelling.
The size of the effect of sanitation on stunting is similar across several independent studies
The diverse array of research that was presented over the two days of the conference was very consistent both qualitatively and quantitatively. The sum total of the evidence discussed suggest that sanitation is very important for child height, and therefore for future achievement. Moreover, several different independent studies show remarkably similar estimates of effect sizes. The evidence from Cambodia and Bangladesh report effect sizes for sanitation that are just about what would be required for sanitation to explain the entire India-Africa height gap, and the evidence from Maharashtra reports one that is larger – not that there still wouldn’t be much more improvement left after getting Indian children to the height of African children.
Research should now explore how to get people to use latrines, and how to design incentives so government officials prioritize sanitation
Since it is now clear from all the research presented in the conference that sanitation is so important for child height, research should now move on to looking into how to do something about it. Why have Cambodia and Bangladesh been able to achieve such huge reductions in open defecation in recent years, and can the same things be done in India? What are the cultural norms surrounding sanitation practices in India? Why do many of the latrines built by the Total Sanitation Campaign remain unused? What kinds of policies would stimulate behavioral change and bring about a reduction in open defecation? What are the supply-side problems in implementing sanitation programs, and how can we minimize leakage so that the number of latrines reported built equal the number of latrines actually built? These are the kinds of questions that the research community should now be focusing on.