WASHINGTON, DC – Air pollution, water pollutants, and global warming are among the environmental factors contributing to the development of kidney disease, according to a presenter at Kidney Week 2019.

The evidence is strongest for air pollution, said Ziyad Al-Aly, MD, FASN, chief of research and education for the Department of Veterans Affairs Health Care System in St. Louis. Fine particles of air pollutants less than 2.5 micrometers in diameter—about 1/20^th the width of a human hair—can get into the capillaries when inhaled and exert effects on the body, he said. Common sources of such PM_2.5 air pollution include land traffic (cars and trucks), power generation, residential energy, and biomass burning, as well as natural sources, such as forest fires.

Air pollution contributes to an estimated 6.5 million deaths per year¹, according to a 2017 study, and ranks fourth in a list of risk factors for all-cause deaths². It falls after high systolic blood pressure, dietary risks, and tobacco use but above factors like high cholesterol and high body mass index. Experimental evidence in mice suggests that PM_2.5 may adversely affect kidney function, leading to tubular and glomerular injury and fibrosis. Studies in people have found higher kidney disease mortality in coal mining areas in Appalachia³ and lower estimated glomerular filtration rate (eGFR) in those who live near major roadways⁴. And, those who live in the midwestern and southern U.S. have a higher burden of chronic kidney disease (CKD) attributable to air pollution⁵. Globally, low- and middle-income countries are disproportionately affected by kidney disease attributable to air pollution⁶. An abstract presented at Kidney Week (#FR-OR051) found an association between exposure to increasing levels of PM_2.5 and risk of death due to CKD.

“We think air pollution is a significant driver of kidney disease and should be considered along with other risk factors as a major contributor to the burden of CKD,” Al-Aly said.

The data is less robust and more heterogeneous regarding water pollution’s impact on kidney disease, he said. Water pollution is estimated to contribute to 0.8-1.8 million deaths per year¹, and pollutants include pesticides and other agricultural products, hydrocarbons, heavy metals such as lead and mercury, and microplastics found in the ocean and fresh water. Studies have found heavy metal pollution leads to tubular injuries and reduced GFR.

There isn’t a lot of data yet on the impact of global warming, Al-Aly said, but it has repercussions on the kidney including acute kidney injury, especially with more frequent, more severe heat waves. Climate change also could lead to a rise in kidney stones, heat stress nephropathy, and infections.

One study⁷ predicts the stone risk “belt” will move north from the southeastern U.S., with the fraction of U.S. population living in high-risk zones for kidney stones growing to 70% by the year 2095. Another more re3cently published study⁸ demonstrated that extreme heat events in cities like Boston, New York, and Philadelphia were associated with an increased risk of hospital admission or mortality among patients with end-stage renal disease.

Human health and planetary health are intimately linked, Al-Aly said, with polluting energy systems being a common contributor to problems with both. “Those who are generally interested in the health of humans really ought to be interested in the health of the planet on which these humans depend on to live and thrive,” he said.

Resources

1. Landrigan PJ, Fuller R, Acosta NJR, et al. The Lancet Commission on pollution and health. Lancet. 2018 Feb 3;391(10119):462-512. doi: 10.1016/S0140-6736(17)32345-0. Epub 2017 Oct 19.
2. Global Burden of Disease, The Lancet, 2017.
3. Hendryx M. Mortality from heart, respiratory, and kidney disease in coal mining areas of Appalachia. Int Arch Occup Environ Health. 2009 Jan;82(2):243-9. doi: 10.1007/s00420-008-0328-y. Epub 2008 May 7.
4. Lue SH, Wellenius GA, Wilker EH, et al. Residential proximity to major roadways and renal function. J Epidemiol Community Health. 2013 Aug;67(8):629-34. doi: 10.1136/jech-2012-202307. Epub 2013 May 13.
5. Bowe B, Xie Y, Li T, et al. Particulate Matter Air Pollution and the Risk of Incident CKD and Progression to ESRD. J Am Soc Nephrol. 2018 Jan;29(1):218-230. doi: 10.1681/ASN.2017030253. Epub 2017 Sep 21.
6. Bowe B, Xie Y, Li T, et al. Estimates of the 2016 global burden of kidney disease attributable to ambient fine particulate matter air pollution. BMJ Open. 2019 May 9;9(5):e022450. doi: 10.1136/bmjopen-2018-022450.
7. Brikowski TH, Lotan Y, Pearle MS. Climate-related increase in the prevalence of urolithiasis in the United States. Proc Natl Acad Sci U S A. 2008 Jul 15;105(28):9841-6. doi: 10.1073/pnas.0709652105. Epub 2008 Jul 14.