Poor sanitation is a better predictor of child stunting than calorie consumption, new data shows. The authors of the >study say, however, that both sanitation and calorie consumption contribute in different ways to health and well-being.

Any new work on malnutrition has been severely hamstrung for the past few years by the absence of new data; the fourth round of the National Family Health Survey, which collects data on underweight and stunted children and adults, is expected to come out with its numbers only in 2014, nearly ten years after the last round. To move beyond this limitation and use new data, the researchers — Dean Spears of the Delhi School of Economics’ Centre for Development Economics, Arabinda Ghosh of the IAS, and Oliver Cumming of the London School of Hygiene and Tropical Medicine — used data on stunting from the HUNGaMA survey of 73,000 households in 112 districts conducted by the Naandi Foundation in 2011. To measure sanitation, they looked at levels of open defecation from the 2011 census.

They found that open defecation was a strong predictor of child stunting; districts with higher levels of open defecation had higher levels of child stunting, even after controlling for other factors like household expenditure, household size and calorie consumption. A 10 per cent increase in open defecation was associated with a 0.7 percentage point increase in both stunting and severe stunting, they said in an article that was published in the peer-reviewed, open-access scientific journal PLOS ONE on Monday night.

The new findings feed into both the more recent interest in heights as an indicator of nutrition, and the previously ignored role of sanitation. Indian children are shorter than those in sub-Saharan Africa despite being richer, and genetic differences have not been able to explain this difference that has for nearly twenty years been referred to as the “Asian enigma.” Moreover, child height can be an important yardstick of health and development; height reflects health and nutrition in the first few years of life, and the same nutritional processes that determine height in the first 24 months also determine cognitive potential, Mr. Spears explained.

While much of the early focus on malnutrition has been related to food consumption, Mr. Spears showed in an earlier paper that open defecation could explain 54 per cent of the variation in average child height between countries, and 65 per cent when population density was considered. Union Rural Development Minister Jairam Ramesh has acknowledged that the role of sanitation has not in the past been given enough importance.

Data from Census 2011 show that close to half of households are forced to defecate in the open. Over three-quarters of the households in Jharkhand, Orissa and Chhattisgarh defecate in the open, while even developed States like Tamil Nadu, Andhra Pradesh, Gujarat and Karnataka have 40-50 per cent open defecation. Just over 10 per cent of India has a toilet with a flush connected to a piped water system. On the other hand, less than 10 per cent of Bangladesh has to defecate in the open.

But the authors caution that they are not pitting sanitation against food consumption as an explanation or solution. “Economists have long recognized that well-being has multiple dimensions: health, wealth, happiness, and food security are only some of the most obvious. The flipside is that poverty can involve multiple deprivations,” Mr. Spears said. “One reason to think about many causes of malnutrition — food, disease, care practices — is that different factors will be more important in different places, and policy should respond to that. Here in India, sanitation is a more important predictor of child height than it is in Africa, in large part because there is greater population density here: if people are living closer together, they are more likely to encounter one another’s germs,” he said. Similarly, while thinking of interventions, a one-size-fits-all policy will get programmes wrong, Mr. Spears said.