Chronic kidney disease affects one in 10 adults worldwide, and in more prosperous countries, it’s often associated with diseases such as diabetes or hypertension. But in the past few decades, young people—primarily agricultural workers from very hot, rural, poor parts of the world—have been showing up at clinics with advanced stages of kidney failure that could not be tied to other conditions.

Photographer and filmmaker Ed Kashi has spent the last five years documenting the effects of CKDu around the world. In a new short film supported by a storytelling grant from the National Geographic Society, Kashi and his colleague Tom Laffay highlight the experience of Mary Pacherres, a young woman living with the disease in Peru who faces pain, fear, and the grim reality of being dependent on dialysis for the rest of her life.

“In Nicaragua, 20,000 people have died from this disease since turn of century,” says Kashi. “In Peru, it hasn't yet reached those epidemic proportions—but it’s the canary in the coal mine.”

Doctors and scientists suspect that dehydration and heat stress—probably in combination with a bevy of other factors, such as heavy metal pollution and pesticide exposure—could be behind the rise in kidney damage cases.

Kidneys act as the clean-up crew for our blood. They filter out toxins and waste, like heavy metals or the indigestible parts of food we eat. But they struggle when they're overloaded or if we don't drink enough water to keep our blood loose and fluid. Once they’re damaged, there’s often no recovery: People have to rely on external dialysis machines to strip waste from their blood.

In places where CKDu is on the rise, it’s possible that people are working too long outside in the baking sun low on water, accumulating damage until they hit a point of no return. That may explain why so many cases appear in regions where it’s hot and the pressure to work in unsafe conditions is strong.

“I see it as a human rights issue,” Kashi says. For him, the disease is an example of how people can ignore a public health crisis in favor of affordable tomatoes or cheap strawberries. “But personally,” he says, “I’m not cool with that.”