At a dialysis center in Atlanta, Lauren Kasper cared for patients who lay in hospital beds, some too sick to be transferred to a chair. Many arrived in wheelchairs or with canes, their bodies weakened by kidney disease.
While connecting patients to dialysis machines, Kasper, a nurse practitioner, was struck by how young many of her patients were.
“The majority of patients you see in a typical outpatient center are in their 60s,” she said. “Some of these patients were in their 20s, 30s and 40s. The fact that they were such a large portion of the population was really shocking.”
In 2022, Kasper co-authored a study about the work histories of these patients. Many had worked in landscaping, roofing or agriculture, where they were exposed to harsh chemicals and extreme heat. The study suggested that people who work in heat-stress environments in a warming climate may be at even greater risk for kidney disease.
“It’s not just the heat, it’s also the humidity. That combination is so taxing on the body and can be very dehydrating,” Kasper said.
This summer, much of the US was baked in deadly, record-breaking heat. While extreme heat Exposure is often linked to acute emergencies such as heat stroke, but researchers are finding it can also contribute to longer-term health problems such as heart disease, cognitive disorder and kidney failure.
When the body is exposed to extreme heat, the cardiovascular system goes into overdrive to keep the body at a safe temperature. Over time, experts say, these functions take a toll on organs like the heart and kidneys — especially for people who exercise outdoors.
“There are certainly risks for outdoor workers in terms of chronic diseases, the main one being chronic kidney disease of unknown origin,” said Kristie Ebi, a professor at the Center for Health and the Global Environment at the University of Washington. “With more research, it is likely that even more will emerge.”
In recent decades, more and more young people have ended up in dialysis centers. Sri Lanka, Central America, India, Saudi Arabia, Taiwan and the US with severe kidney damage and none of the typical risk factors, such as diabetes, autoimmune disease or severe high blood pressure.
Researchers say it is still unclear whether heat is the main cause of the disease in otherwise healthy young people, or whether other factors, such as pesticides, contaminated drinking water or the use of painkillers, also play a role.
“This is probably multifactorial, multiple things coming together, coalescing, and creating the perfect storm for farmworkers to have kidney dysfunction,” said Roxana Chicas, a registered nurse and professor at Emory University. “But I do think dehydration is one of the biggest players, along with heat exposure — the high, ambient heat that they’re exposed to and working very hard.”
Kidneys filter blood, removing waste and excess fluid from the body. But heat exposure and dehydration can reduce blood flow to the kidneys, starving them of oxygen; they can become inflamed and break down muscle tissue, releasing certain enzymes that can damage the kidneys.
“We think of heat as an accelerator” for kidney damage that builds up over time, said Shuchi Anand, a nephrologist at Stanford University.
While workers in different sectors are vulnerable to extreme heat, researchers said agricultural workers — many of whom are immigrants with few labor protections — face specific risk factors, such as pay systems that discourage water breaks.
In May Chicas published a study that found that workers who were paid piece rates for the amount of food they picked, rather than hours worked, had higher rates of acute kidney injury. She said workers who are drenched in sweat often push themselves to pick fruits and vegetables as quickly as possible. “It’s almost suffocating to breathe because it’s so hot and humid. They describe it as working in an oven,” Chicas said.
They know they need to drink water and take breaks to stay safe, she said. “But that’s really hard when there’s so much demand and wages are so low that they have to push themselves to meet their quota.”
She said some workers with kidney disease eventually return to their home countries because they don’t have access to health care in the U.S. and their families back home can care for them.
Heat protection for workers in the U.S. is currently a patchwork. Only a handful of states have heat exposure standards, while some states, notably Florida and Texas, prohibit local governments from implementing protections. In July, the Biden administration suggested a national heat standard that could go into effect next year, affecting some 36 million workers. Experts say such a standard could help prevent a wave of heat-related illnesses.
Researchers are still figuring out what prolonged exposure to higher temperatures means for the general population. Ebi, the University of Washington professor, noted that people have been living in different temperatures for a long time, and the body adapts over time.
But Chicas said what’s happening to farmworkers is a warning to people who may not feel at risk right now. “Farmworkers, who are on the front lines of climate change, are already giving us a glimpse of this kidney dysfunction that’s associated with rising temperatures,” Chicas said. “In a warming climate, we could all be at risk for this.”
