A global study says children living in river basins whose watersheds have greater tree cover are less likely to experience diarrhoeal disease, the second leading cause of death for children under the age of five.
Published in Nature Communications today, the University of Vermont-led study, supported by the Luc Hoffmann Institute, is the first to quantify the connection between watershed quality and individual health outcomes of children at the global scale. It looked at 300,000 children in 35 countries.
“Looking at all of these diverse households in all these different countries, we find the healthier your watershed upstream, the less likely your kids are to get this potentially fatal disease,” says Taylor Ricketts of UVM’s Gund Institute for Environment.
The team predicts that a 30% increase in upstream tree cover in rural watersheds would have a comparable effect to improved water sanitation such as the addition of indoor plumbing or toilets.
“This suggests that protecting watersheds, in the right circumstances, can double as a public health investment,” says Brendan Fisher of UVM’s Gund Institute and Rubenstein School of Environment and Natural Resources. “This shows, very clearly, how healthy ecosystems can directly support human health and welfare.”
The research is the first to use a massive new database that will enable ‘big data’ approaches to study links between human health and the environment, globally. The database features 30 years of USAID demographic and health surveys, with 150 variables for 500,000 households, including spatial data on the environment.
“We are not saying trees are more important than toilets and indoor plumbing,” says Diego Herrera, who led the paper as a UVM postdoctoral researcher, and is now at Environmental Defense Fund. “But these findings clearly show that forests and other natural systems can complement traditional water sanitation systems, and help compensate for a lack of infrastructure.”
The researchers hope the findings will help governments and development agencies to improve the health and environment of children around the world. They add that more research is needed to more fully understand exactly how watershed forests impact the risk of diseases like diarrhoea, which has many causes, including waterborne pathogens.
“For more than 40 years case studies around the world have suggested that ecosystem degradation has a disproportionate impact on the world’s poorest people,” says Jonathan Hutton, Director of the Luc Hoffmann Institute. “This study uses big data to demonstrate the strongest possible link between forest quality, water quality and human health. It is a significant piece of evidence in the case for better management of our river basins and other natural systems.”
The research covers 35 nations across Africa, Southeast Asia, South America and the Caribbean, including Bangladesh, Philippines, Nigeria, Colombia, and the Democratic Republic of the Congo.
The study was supported by the National Socio-Environmental Synthesis Center (SESYNC), the Luc Hoffmann Institute and WWF, along with The Gordon and Betty Moore Foundation and The Rockefeller Foundation as part of the Health & Ecosystems: Analysis of Linkages (HEAL) programme.
The interdisciplinary research team was led by Brendan Fisher and Taylor Ricketts of the University of Vermont (who also led the database’s creation) and includes lead author Diego Herrera (Environmental Defense Fund/UVM), Alicia Ellis (UVM), Christopher Golden (Harvard University), Timothy Treuer (Princeton University), Alexander Pfaff (Duke University), Kiersten Johnson (USAID), and Mark Mulligan (King’s College London).
According to the World Health Organization (WHO):
Read more about the Watersheds and human health project.
