During the growing season, sugarcane workers in Guatemala cut on average six tons of sugarcane per day, six days a week. This population, like many agricultural workers in hot climates, is at increased risk of chronic kidney disease of unknown cause.

In the United States, mortality from chronic kidney disease has declined, but worldwide it is increasing. Unlike chronic kidney disease with known causes such as diabetes, which increases in prevalence with age, this type of kidney disease is seen in younger and middle-aged adults and sometimes even children.

The prevalence of chronic kidney disease has increased dramatically, affecting more than 800 million people worldwide. Mortality has doubled over the past 20 years, sparking a public health exploration into the epidemic.

The causes of what’s been called “chronic kidney disease of unknown cause” in the public health literature are beginning to be identified: heat stress, dehydration, water quality, and pollution. This type of chronic kidney disease is a multifactorial problem that is expected to worsen.

“You’re going to hear more about it,” public health researcher Lee Newman, M.D., of the University of Colorado, Anschutz, told an audience at the National Association of Science Writers meeting in November. Journalists need to raise awareness about this condition’s rising prevalence and the emerging research about its prevention.

Heat stress and food insecurity

Research has implicated increasing heat and sometimes water quality or pollution in the epidemic. A 2020 analysis estimated that 26.2 million cases of chronic kidney disease worldwide were attributable to heat stress. The people most affected do hard manual labor outdoors in places with warm climates, especially countries in Africa, Asia, and Latin America. In Sri Lanka, multiple nephrotoxins in the water and increasing temperatures have been implicated in the high rates of chronic kidney disease there.

The increasing prevalence of chronic kidney disease not only affects worker safety but also intersects with food insecurity. When agricultural workers can’t do their jobs, food prices and supply networks are disrupted.

For the sugarcane workers in Guatemala, their employer, Pantaleon, the largest sugar producer in the world, approached Newman to address this worker safety issue. Newman’s team revealed that sugarcane workers experienced kidney stress through the growing season, but sufficient rest and hydration allowed them to recover. By adding rest breaks to cool down and offering clean water with electrolytes, the workers’ kidney stress could be mitigated.

Agricultural workers are often discouraged from taking breaks because they’re paid according to their productivity. Not only did Newman’s team recommend alternative pay structures for workers, they also explored methods to incentivize workers to remain hydrated. For example, they offered a raffle based on urine color.

Workers who showed up to work hydrated or improved their hydration over a shift were offered tokens to enter a raffle for a prize. They also talked to workers who showed signs of kidney injury, educating them about prevention and offering them medical referral or lighter work options. Most of these workers stabilized or even improved.

Newman’s research in Guatemala addresses the specific factors that led to chronic kidney disease there. But each population is different, as the research in Sri Lanka shows. The causes leading to increased kidney disease can be complex and may require multiple interventions. Newman recommends that as journalists cover labor issues like heat stress and kidney injury, they ask questions about implementation, a term for research that assesses the feasibility of worker safety measures.

Additional resources

• Heat at Work: Implications for Safety and Health, International Labor Organization.
• Sugarcane workweek study: Risk factors for daily increase in creatinine, Kidney International Reports.
• Workplace screening identifies clinically significant and potentially reversible kidney injury in heat-exposed sugarcane workers, International Journal of Environmental Research and Public Health.
• Enfermedad renal crónica de causa desconocida: investigaciones en Guatemala y oportunidades para su prevención, Ciencia, Tecnología y Salud.
• Occupational heat exposure alone does not explain chronic kidney disease of uncertain aetiology (CKDu) in Sri Lanka, Journal of Climate Change and Health.
• Occupational paraquat and glyphosate exposure may decline renal functions among rural farming communities in Sri Lanka, International Journal of Environmental Research and Public Health.
• Epidemiology of chronic kidney disease: an update 2022, Kidney International Supplements.
• A warming climate heightens focus on kidney disease, University of Colorado, Anschutz, press release.
• Electrolyte beverage intake to promote hydration and maintain kidney function in Guatemalan sugarcane workers laboring in hot conditions, Journal of Occupational and Environmental Medicine.
• Workers’ health and productivity under occupational heat strain: a systematic review and meta-analysis, The Lancet Planetary Health.
• What’s Driving the Spike in Kidney Disease in the Tropics?, Duke Global Health Research Institute Research News.

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