Photo by Ed Kashi. Sugar cane workers cutting in burned fields, with dust monitors on their chests, as part of the Adelante Initiative at the Ingenio San Antonio, or San Antonio Sugar Mill, in Chichigalpa, Nicaragua, on February 24, 2020.
Citation: Kidney News 16, 4
Chronic kidney disease of unknown etiology (CKDu) has been called “the black lung of climate change” (1). CKDu was first reported in the early 2000s to describe localized regions of high prevalence of CKD among young people without diabetes or hypertension in Central America and Southeast Asia (2, 3). The cause of this chronic tubulointerstitial nephritis is likely multifactorial (Table 1). Lead suspects include heat stress and toxic environmental exposures such as agrichemicals or heavy metals. Although there is disagreement among researchers over the exact combination of factors leading to the disease, most agree that heat plays some role in its development. CKDu is endemic in regions with high ambient temperatures, and it is strongly associated with occupational heat exposure in agriculture and other sectors. CKD could develop secondary to daily subclinical acute kidney injury from heat exposure, volume depletion, and exercise-induced hyperuricemia (4, 5). Heat may also exacerbate kidney injury from environmental exposures (such as contaminated water) and/or alter the body's response to xenobiotic elements (3). CKDu is often diagnosed at advanced stages of disease, and patients commonly progress to kidney failure within several years (2).
Proposed CKDu contributing factors of a multifactorial disease
Since this disease has emerged relatively recently and people have been laboring in hot environments for millennia, one of the main scientific questions is “Why now?” A plausible answer is “climate change.” There has been an increase in average temperature of 0.18° C per decade globally and an increase in frequency and severity of heat waves over the past 50 years (4, 6). However, all parts of the globe are not affected uniformly, and certain CKDu localities, such as a CKDu endemic area of Nicaragua, had an increase in 0.7° C per decade between 1970 and 1990 (7). Workers in endemic areas with strenuous occupations, such as harvesting sugarcane, are frequently exposed to temperatures high enough that the Occupational Safety and Health Administration recommends extensive rest, shade, and rehydration interventions. Unfortunately, these interventions are inconsistently performed (4, 8).
Occupational health policies and interventions are extremely important to protect workers; however, these measures alone are insufficient in addressing a likely key driver of the disease—climate change. CKDu is a result of environmental injustice, in which low-income communities with limited political power and health care access are harmed by entities from which they do not benefit. Children and women, two especially vulnerable populations within communities, are severely impacted by the societal impacts of CKDu, and there is growing evidence that they too experience CKDu-related kidney injury (3, 9). Current CKDu-focused efforts include the CKDu in Agricultural Communities (CURE) Research Consortium, the International Society of Nephrology's (ISN's) CKDu Network (i3C), and the Consortium on the Epidemic of Nephropathy in Central America and Mexico (CENCAM). Through interdisciplinary, interinstitutional, and international collaboration, all CKDu underlying factors, including heat stress, can be identified and addressed.
The nephrology community must take environmentally protective actions, as described in the ASN's Statement on Climate Change (10), to curb the CKDu epidemic. We need more population-level research on climate change health effects, climate change-related disaster relief preparedness for patients with kidney diseases, and advocacy for public policies that protect the environment. The nephrology community should also promote environmentally sustainable kidney care, as outlined by the ISN's Global Environmental Evolution in Nephrology and Kidney Care (GREEN-K) initiative, with a focus on limiting the environmental impact of dialysis treatments (11). CKDu is a wake-up call to the immediate necessity of protecting the environment, our patients, and vulnerable populations around the globe.
Footnotes
References
- 1.↑
Baker A. Chronic kidney disease is poised to become the black lung of climate change. Time. August 9, 2023. Accessed January 18, 2024. https://time.com/6303020/chronic-kidney-disease-climate-change/
- 2.↑
Johnson RJ, et al. Chronic kidney disease of unknown cause in agricultural communities. N Engl J Med 2019; 380:1843–1852. doi: 10.1056/NEJMra1813869
- 3.↑
Jayasumana C, et al. Chronic interstitial nephritis in agricultural communities: A worldwide epidemic with social, occupational and environmental determinants. Nephrol Dial Transplant 2017; 32:234–241. doi: 10.1093/ndt/gfw346
- 4.↑
Glaser J, et al. Climate change and the emergent epidemic of CKD from heat stress in rural communities: The case for heat stress nephropathy. Clin J Am Soc Nephrol 2016; 11:1472–1483. doi: 10.2215/CJN.13841215
- 5.↑
Roncal-Jimenez C, et al. Heat stress nephropathy from exercise-induced uric acid crystalluria: A perspective on Mesoamerican nephropathy. Am J Kidney Dis 2016 67:20–30. doi: 10.1053/j.ajkd.2015.08.021
- 6.↑
Lindsey R, Dahlman L. Climate change: Global temperature. National Oceanic and Atmospheric Administration. Climate.gov. January 18, 2024. https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature
- 7.↑
Petropoulos ZE, et al. Climate trends at a hotspot of chronic kidney disease of unknown causes in Nicaragua, 1973–2014. Int J Environ Res Public Health 2021; 18:5418. doi: 10.3390/ijerph18105418
- 8.↑
García-Trabanino R, et al. Heat stress, dehydration, and kidney function in sugarcane cutters in El Salvador—a cross-shift study of workers at risk of Mesoamerican nephropathy. Environ Res 2015; 142:746–755. doi: 10.1016/j.envres.2015.07.007
- 9.↑
Gunasekara TDKSC, et al. Urinary biomarkers indicate pediatric renal injury among rural farming communities in Sri Lanka. Sci Rep 2022; 12:8040. doi: 10.1038/s41598-022-10874-w
- 10.↑
American Society of Nephrology. Statement on climate change. April 22, 2022. https://www.asn-online.org/policy/webdocs/22.4.22StatementOnClimateChange.pdf
- 11.↑
International Society of Nephrology. New global initiative on environmentally sustainable kidney care. Accessed January 18, 2024. https://www.theisn.org/blog/2023/07/03/new-global-initiative-on-environmentally-sustainable-kidney-care/
