Kidney Risks of Climate Change: A Growing Concern

/kidneynews/11_9/1/graphic/1f1.jpg

An epidemic of CKD among agricultural workers in different parts of the world has scientists searching for the potential cause. Among the chief suspects—although not the only one—is climate change–related heat stress.

As scientists work to verify whether climate change is contributing to the epidemic, concern about the potential health impacts of climate change around the world is growing. A 2017 report from the United Nations outlined the health risks associated with climate change, including increases in vector-borne diseases and extreme weather events, both of which can contribute to new kidney disease and put patients with existing kidney disease at risk (1). There is also growing evidence that rising temperatures increase the risk of kidney stones and AKI.

“Temperatures are increasing throughout the world, and whether or not we think it’s manmade, everyone acknowledges that temperatures have been increasing,” said Richard Johnson, MD, Tomas Berl Professor in the Division of Renal Diseases and Hypertension at the University of Colorado in Aurora. He noted that temperatures have increased about 1 degree Centigrade over the past 50 to 100 years, and although that may not sound like much, it’s contributing to heat waves and other extreme weather events.

Canary in a coal mine?

When alarming numbers of young agricultural workers without traditional risk factors like diabetes, hypertension, or glomerular disease started showing up in Central American hospitals in the 1990s with ESKD, clinicians were concerned, noted Johnson and colleagues in a recent review in the New England Journal of Medicine (2). Johnson explained that the cases were clustered among laborers likely exposed to heat stress, which is a known risk factor for AKI. The initial reports led to the identification of clusters of CKD in Honduras, Nicaragua, El Salvador, and Guatemala, he said.

“The thing that was striking was that there are so many people developing this condition, and it looks like it’s been increasing,” Johnson said. “These countries now have some of the highest rates of kidney failure in the world. It’s partly because of this.”

Similar clusters of CKD have since been identified in agricultural workers in Sri Lanka and India. But not all areas where agricultural workers log long hours in hot conditions have seen an uptick in CKD, Johnson noted. Scientists are exploring several potential culprits that might contribute to kidney damage, including toxic agricultural chemicals, heavy metal exposure, silica inhalation, infectious diseases that may cause kidney injury, genetic vulnerabilities, repeated heat stress, or some combination of these risk factors.

“The jury is still very much out on whether heat is the primary driver,” said Katherine Barraclough, MD, a consultant nephrologist at the Royal Melbourne Hospital and associate professor at the University of Melbourne in Australia. “It is reasonable to assume, though, that even if heat turns out to not be the primary driver, it has the potential to contribute to or exacerbate kidney dysfunction from any cause, and therefore needs to be treated as a risk factor and managed.”

Johnson and his colleagues are testing their hypothesis that repeated heat stress and dehydration in the workers are contributing to low-grade kidney injury by comparing the weather and climate maps with the clinical data they are collecting in workers in Central America. Johnson doesn’t rule out other potential contributing factors, but he believes that heat is playing a substantial role.

“If I’m right, we’re going to continue to see these outbreaks occurring in more and more places as climate change occurs,” Johnson said.

Already, scientists in the United States have identified high rates of AKI among agricultural workers in California (3) and Florida (4), who may also be exposed to extreme heat and poor hydration. Poor working conditions likely are contributing to the kidney harms documented among agricultural workers and have led to some prevention efforts such as promoting better hydration, Johnson noted.

Roberto Lucchini, MD, a professor at the Icahn School of Medicine at Mount Sinai in New York, who studies the health effects of occupational exposures, spoke recently at an event held by the El Programa Salud, Trabajo y Ambiente (SALTRA) in Panama about climate-related health concerns. He said both companies and ministries of health throughout Central America are concerned and are looking for ways to prevent this unexplained form of CKD. He noted that the associated costs for dialysis and other end stage renal care for the countries are substantial.

“They want to put some resources into understanding the ways to target the disease, to prevent the disease,” Luchini said. For now, he said there is a need to get a better handle on the epidemiology of the disease. Additionally, he noted, nephrologists in the region are working to develop uniform diagnostic criteria that may help improve the ability to pool their data.

Prevention emphasized

Whereas climate-related CKD risks continue to be investigated, the growing risk of kidney stones and AKI linked to rising temperatures and extreme weather events has been well established, noted Barraclough in a recent review in Kidney International (5). For example, in the United States, scientists have linked rising temperatures to an increased risk of kidney stones (6), and scientists in Australia have linked heat waves to increased emergency department admissions for AKI and kidney stones (7).

“There is an increased risk of both AKI and [kidney stones] with rising temperatures—this is clear and well documented,” she emphasized. She noted that the elderly, patients with CKD or existing kidney stones, and those taking certain medications like diuretics, β-blockers, and angiotensin-converting enzyme inhibitors are at increased risk for those heat-related harms. Barraclough emphasized the importance of nephrologists advising their patients to stay well hydrated and cool, to avoid strenuous activity, and to follow their physician’s recommendations about medication adjustments during extreme heat events.

In addition to rising temperatures, climate change is contributing to extreme weather events like hurricanes, which pose considerable risks to patients with ESKD who rely on dialysis. When Hurricanes Irma and Maria clobbered the Caribbean in 2017, emergency personnel and clinicians scrambled to evacuate dialysis patients or to piece together care for them in the absence of electricity and with medications hard to access (8). In the aftermath of Hurricane Katrina in 2005, the Kidney Community Emergency Response Coalition developed recommendations for dialysis centers and their patients (9). Barraclough highlighted the report’s recommendations that both facilities and patients have emergency plans in advance.

“Nephrologists need to be involved at all stages, either doing the work [by] educating patients about what they are able to eat and drink when in the midst of a disaster and unable to access dialysis or providing input into higher-level preparedness planning,” she said.

There have been growing efforts among physicians and medical institutions to draw attention to the need to address climate change. For example, the Lancet Countdown was established to monitor the health effects and response to climate change (10). Peter Blankestijn, MD, a nephrologist at the University Medical Center in Utrecht, The Netherlands, argued in a recent commentary that the countdown should be a call to action for nephrologists (11). He explained in an interview that not only does climate change impact health, but also healthcare contributes to climate change—for example, through the production of waste, carbon emissions, and energy use.

“[This] is very much in conflict with the basic principle in medicine of ‘first do no harm,’” he said. The first step to reducing that harm, he said, is becoming aware of it and helping to alert others. He noted that the European Renal Association—European Dialysis and Transplant Association will be featuring sessions on climate change at its next meeting in Milan, Italy.

Barraclough also recommended that kidney patients and nephrologists get involved in efforts to help curb climate change. She noted in her review that it may not be possible to stop climate change in the near term, but a concerted global effort may be able to limit warming to 2 degrees Centigrade. Additionally, many interventions to combat climate change may have other health benefits as well, she noted. For example, adopting a plant-based diet or walking or bicycling instead of driving may contribute to improved overall health and well-being in addition to reducing emissions that contribute to climate change. Barraclough noted that clinicians in particular can be powerful advocates.

“I personally think speaking out is our responsibility—it is our job to protect health, and we must speak on behalf of those with less of a voice—this includes those vulnerable populations who will be most impacted by the health effects of climate change and future generations,” she said.

September 2019 (Vol. 11, Number 9)

References

1. United Nations Climate Change. Climate change impacts human health. April 12, 2017. https://unfccc.int/news/climate-change-impacts-human-health.

2. Johnson RJ, et al Chronic kidney disease of unknown cause in agricultural communities. N Engl J Med 2019; 380:1843–1852.

3. Moyce S, et al Heat strain, volume depletion and kidney function in California agricultural workers. Occup Environ Med 2017; 74:402–409.

4. Mix J, et al Hydration status, kidney function, and kidney injury in Florida agricultural workers. J Occup Environ Med 2018; 60:e253–e260.

5. Barraclough KA, et al Climate change and kidney disease—threats and opportunities. Kidney Int 2017; 92:526–530.

6. Brikowski TH, et al Climate-related increase in the prevalence of urolithiasis in the United States. Proc Natl Acad Sci USA 2008; 105:9841–9846.

7. Borg M, et al Using the excess heat factor to indicate heatwave-related urinary disease: A case study in Adelaide, South Australia. Int J Biometeorol 2019; 63:435–447.

8. Kuehn BM. Dialysis in disaster zones: Back-to-back disasters put response systems to the test. Kidney News December 2017 (Vol. 9, No. 12). https://www.kidneynews.org/kidney-news/current-issue/dialysis-in-disaster-zones-back-to-back-disasters-put-response-systems-to-the-test.

9. Kopp JB, et al Kidney patient care in disasters: Emergency planning for patients and dialysis facilities. Clin J Am Soc Nephrol 2007; 2:825–838.

10. Watts N, et al The 2018 report of the Lancet countdown on health and climate change: Shaping the health of nations for centuries to come. Lancet 2018; 392:2479–2514.

11. Blankestijn PJ, et al Lancet countdown paper: What does it mean for nephrology? Nephrol Dial Transplant 2019; 34:4–6.