By Dr. Alan Dangour
Globally, about 165 million children under 5 years of age have stunted growth – that means that they are much shorter than they should be and compared to children with normal height, stunted children are at increased risk of becoming shorter adults, they perform less well at school and have lower social and economic potential.
Why do children become stunted? Well, physical growth of children is directly affected by two critical factors: consumption of sufficient food of adequate nutritional content, and disease. And children who consume poor diets especially in the first two years of life, and live in dirty environments causing them to have repeated bouts of diarrhoea are much more likely to grow badly and end up short. And this is largely irreversible!
We know that access to good quality water, improved sanitation and enhanced hygiene (WASH) practices lead to decreased levels of diarrhoea in children – this is really important information that has driven many international funding and advocacy initiatives. What we didn’t know was whether this reduction in diarrhoea in children who had access to clean water, and improved sanitation and hygiene practices would also improve the growth of children. It makes sense that it would, but no one had ever asked the question before!
So, we conducted a systematic review of studies that evaluated the effect of WASH interventions on the growth of children. It’s possible to think of both direct and indirect pathways linking WASH and child growth: direct pathways (diarrhoea, environmental enteropathy and worm infections) relate to the body’s ability to respond to infection or parasitic infection and the impact of these on growth, while indirect pathways, such as time taken to collect water at long distances from the home (taking time away from childcare) relate more to the ability of families to provide safe and clean living environments for their children.
The indirect pathways are really important, but in our review we focussed on the direct pathways and identified 14 studies conducted in 10 low- and middle- income countries (Bangladesh, Ethiopia, Nigeria, Chile, Guatemala, Pakistan, Nepal, South Africa, Kenya and Cambodia) that provided data on the effect of WASH interventions on 9,469 children under 5 years of age. Five of the studies were cluster-randomised controlled trials, whilst the remaining 9 were non-randomised studies.
We combined the data from the five cluster-randomised controlled trials in a meta-analysis to estimate the overall effect of WASH interventions on growth in children. Our analysis suggested that WASH interventions (specifically solar disinfection of water, provision of soap and improvement of water quality with an intervention time of 9 – 12 months) slightly but significantly increased the height of children under 5 years of age.
This is a really exciting result that suggests that WASH interventions can have an important impact on the growth (and therefore the life-chances) of children living in low- and middle-income countries. But of course, as with all academic studies, there are some caveats – the studies were all quite short in duration and we really need to know the longer-term effects; there were no studies that looked at the effect of sanitation interventions, and finally all of the studies included in the review had some methodological shortcomings.
So, it’s exciting and has helped focus international attention on the potential role of WASH interventions in improving not only the health but also the physical growth of children, but there’s still work to do to confirm the findings. Luckily there’s lots of research underway and we should be in a better position to answer the question more fully in the near future!
Alan Dangour is a public health nutritionist at the London School of Hygiene & Tropical Medicine, a world-leading research institute with a mission to improve health and health equity in the UK and worldwide