Fighting the climate disease of our time

As a Duke doctor studying the rise of kidney disease in Costa Rica, Anna Strasma has seen first-hand the toll of climate change on the human body. 

Recent research from Strasma and other researchers across the university is uncovering a link between the effects of extreme heat and the disease. In a warming climate, people working in heat-stressed environment may be at greater risk of kidney disease. 

In Costa Rica, a country known for its sugarcane farming, thousands of farmers and agricultural workers endure long hours under scorching sun, working in fields that are regularly more than 100 degrees. Over time, a multitude of related factors are leading to death.  

“Christmases are really sad here because there are no dads around anymore,” Strasma recalled a community member telling her. 

While heat exposure is a clear risk factor, Strasma, a nephrologist, says researchers at Duke are uncovering what could be a multitude of contributing factors to the rise in kidney disease—not only in Costa Rica but in other farming communities across the world in Sri Lanka, India, and throughout Central America. They are studying exposure to pesticides, heavy metals in drinking water, and genetics, along with extreme heat, as contributing factors.  

Heat stress can harm the kidneys by reducing their oxygen supply as the body tries to cool down, triggering inflammation. It also can lead to heavy sweating, causing dehydration that can make it harder for the kidneys to do their job. 

One of the biggest challenges is diagnosing the disease early. Symptoms don’t typically appear until the kidneys are already severely damaged. And, unlike kidney disease caused by diabetes or hypertension, there are no proven treatments to slow the progression of chronic kidney disease. 

Since the 1990s, the epidemic of chronic kidney disease has been unfolding in farming and agricultural communities across the world, often without warning or explanation, says Nishad Jayasundara, the Juli Plant Grainger Assistant Professor of Global Environmental Health at the Nicholas School of the Environment, who studies chronic kidney disease in Sri Lanka, Kenya and other countries. Agricultural workers, particularly men in their 30s and 40s, are succumbing to the disease. 

“What we’re seeing is a rise in communities with no other major risk factors typically known to affect kidney health,” Jayasundara says. “Perfectly healthy, able-bodied men in farming communities who’ve worked in hot, dry conditions for years are suddenly showing up at the hospital with stage-four kidney failure.” 

Jayasundara studies a community in his native country of Sri Lanka where 60 percent of people have kidney failure. He gathers data on heat from both satellites and monitors worn by agricultural workers to better understand the connection between climate change and chronic kidney disease. 

“If I were to predict who has kidney failure in these communities, I can best predict it based on how well-built their house is,” he says. “Poverty is the common denominator.” The poorest laborers, lacking air conditioning and proper shelter from the heat, are the most exposed to intense heat stress as well as a high burden of chemical contaminants—both in their homes and at work, he says.  

Research is also underway to look at whether agricultural workers in North Carolina, who harvest crops such as tobacco, Christmas trees and sweet potatoes, might be at risk too. 

While education and self-care measures—such as staying hydrated and resting in the shade—can help, Strasma stresses the need for systemic changes. For example, there is no federal standard protecting workers from heat, and while some states are taking steps, North Carolina remains without such measures. 

Duke’s academic research is leading the way in meeting the challenges.  

Jayasundara is part of a broad initiative of experts from Duke University, Duke University School of Medicine, the National Institute of Environmental Health Sciences and the University of North Carolina at Chapel Hill—called the Environmental Exposures and Kidney Health group—who have been working to understand how climate change plays a role in kidney disease.  

In addition, Duke’s Heat Policy Innovation Hub, the first program in the U.S. dedicated to cross-disciplinary innovation in extreme heat policy and practice, is bringing together scientists and communities to develop and deploy innovative ways to reduce the impact of extreme heat on human health. Through a recent award from the U.S. Department of Commerce and National Oceanic and Atmospheric Administration, hub researchers will spend the next two years building an interactive web tool to help policymakers understand heat stress in rural and coastal communities and plan for it.  

As heat exposure continues to claim lives as the leading cause of climate-related death, Duke researchers have hope they can begin to change outcomes across the world and in North Carolina.  

“We have to think globally to protect these communities,” Jayasundara says, “And ultimately, [that will] help all of us.”