New research suggests that a combination of high heat, toxins, and infections may be responsible for the increasing prevalence of chronic kidney disease among agricultural workers.
Chronic kidney disease (CKD) involves the slow loss of kidney function. Kidneys keep the body healthy by filtering dangerous fluids and waste products from the blood. When kidney function is impaired, these products build up in the body and cause disease.
People with CKD may develop high blood pressure, anemia, weak bones, and nerve damage. Also, kidney failure increases the risk of cardiovascular disease. These complications may happen slowly over a long period.
Causes of CKD include diabetes and high blood pressure, which are responsible for up to two-thirds of the cases. Early diagnosis and treatment can prevent many complications. High blood pressure may cause CKD, which, in turn, may lead to high blood pressure.
According to the National Kidney Foundation, 30 million adults in the United States live with CKD, and millions of others are at risk. Heart disease is the leading cause of death for all people with this disease.
Finding potential causes of CKD epidemic
Recently, CKD has been prevalent among workers in hot climates. In the 1990s, the disease affected sugarcane workers in Central America. In 2012, 20,000 people in California, Florida, and Colorado died from the disease, but the cause remained unknown.
Researchers from the University of Colorado Anschutz (CU Anschutz) Medical Campus looked at all the available studies to consolidate the information and find potential gaps in research. The results of the study appear in the New England Journal of Medicine.
The research team found that agricultural workers, such as those who worked with sugarcane, cotton, and corn, as well as shrimp farmers and miners, are more likely to develop the disease compared with those who work at higher altitudes.
The researchers believe that high temperatures, caused by climate change, and pesticides, such as glyphosate, could play a role in this chronic disease "epidemic."
Sri Lankan farmers exposed to glyphosate showed a high risk for CKD. The researchers also investigated heavy metals, such as lead and cadmium, which are common culprits of kidney injury in Sri Lanka and Central America.
Dr. Lee Newman, MA, who is also the director of the Center for Health, Work & Environment and a professor in the Department of Environmental & Occupational Health at the Colorado School of Public Health, led the team.
"Some pesticides are nephrotoxic, and these could possibly contaminate the water supply. [...] Indeed, there are studies showing the epidemic in Sri Lanka is greatest in areas where there are shallow wells in which toxins might become concentrated," adds Dr. Richard Johnson, from the University of Colorado School of Medicine and co-author of the study.
Other possible causes, which are common among sugarcane workers, include infectious diseases that can affect the kidneys, such as the hantavirus and leptospirosis, and genetic factors. Dr. Newman added that heat exposure, heavy labor, and persistent dehydration are also culprits.
CKD 'epidemic' is spreading fast
The disease is appearing in the U.S. and affecting rural workers in Florida, California, and Colorado. Dr. Newman notes that "this is not the usual kidney disease [because] it is not caused by high blood pressure or diabetes."
"It is my opinion that climate change plays a role in this epidemic," Dr. Johnson says. He points out that CU Anschutz is currently looking at the health of workers and how climate change is impacting the disease.
Talking about the prevalence of the disease among rural workers, Dr. Johnson adds: "They are the people who feed the planet. [...] If climate change continues like this who is going to feed us?"
The results of the new study suggest that the cause of this CKD epidemic may be a combination of climate change, toxins, and infections.
Drs. Newman and Johnson believe that institutions need to take action to prevent the epidemic by ensuring that workers take proper breaks, stay hydrated, and spend time out of the sun. Dr. Johnson and colleagues conclude:
"When clinicians detect clusters of patients with [CKD] who work for the same employer or in similar jobs, they should contact occupational health and safety and public health professionals to promote investigations of workplace conditions."