Science Selection September 2016 | Volume 124 | Issue 9
PM2.5 and Kidney Function: Long-Term Exposures May Lead to Modest Declines
Nate Seltenrich covers science and the environment from Petaluma, CA. His work has appeared in High Country News, Sierra, Yale Environment 360, Earth Island Journal, and other regional and national publications.
Citation: Seltenrich N. 2016. PM2.5 and kidney function: long-term exposures may lead to modest declines. Environ Health Perspect 124:A168; http://dx.doi.org/10.1289/ehp.124-A168
Published: 1 September 2016
PDF Version (433 KB)
Related EHP Article
Long-Term Exposure to Ambient Fine Particulate Matter and Renal Function in Older Men: The Veterans Administration Normative Aging Study
Exposure to fine particulate matter (PM2.5) is associated with cardiovascular health impacts including increased risk of irregular heartbeat and pulmonary embolism (arterial blockage).1 However, the relationship between PM2.5 and renal function, an independent cardiovascular risk factor2,3 and significant health metric in its own right,4,5,6,7 is poorly understood. A new longitudinal study offers early evidence that PM2.5 exposure is associated with lower kidney function and a higher rate of kidney function decline over time.8
“While there is evidence that the association between ambient particulate matter and cardiovascular disease may be explained by several pathways at the molecular or functional level, the underlying mechanisms that may explain the association remain to be fully elucidated,” says lead author Amar Mehta, a visiting scientist at the Harvard T.H. Chan School of Public Health.
Reductions in renal function like those seen in the older men in this study probably would not harm individuals with healthy kidneys. However, they could set the stage for cardiovascular impacts in the elderly.
© Albrecht Weißer/Getty Images
The research team compared PM2.5 exposure and renal function for 669 predominately white men with a mean age of 73.5 years enrolled in the Boston-based Department of Veterans Affairs Normative Aging Study.9 At up to 4 physical examinations between 2000 and 2011, each participant had his serum creatinine levels read and eGFR (estimated glomerular filtration rate) calculated as a measure of renal function. The researchers estimated participants’ exposure to PM2.5 over the year prior to each visit, based on the men’s home addresses and incorporating high-resolution satellite data.
Participants’ median 1-year PM2.5 exposure levels ranged from approximately 7.5 to 12.5 µg/m3. By comparison, the primary National Ambient Air Quality Standard for 1 year is 12 µg/m3 averaged over 3 years.10 This standard is designed to be protective of all groups of people, including the elderly. For this particular population, the authors estimated that a 2.1-µg/m3 increase in PM2.5 over a 1-year period was associated with a reduction in eGFR comparable to that seen with a 2-year increase in age in the same men.8
Joel Kaufman, a physician, epidemiologist, and professor at the University of Washington, questions the clinical significance of the change in eGFR as far as renal function goes. Based on the evidence so far, he says, “these air pollution levels are not going to cause someone with normal kidney function to need dialysis.” Kaufman was not involved in the study.
On the other hand, the implications for cardiovascular disease risk could potentially be significant. Brown University associate professor Gregory Wellenius, who coauthored a 2013 paper examining associations between air pollution and renal function,11 says, “The effect is small numerically, but when you compare it to a two-year aging of an individual, it isn’t trivial in this elderly and potentially vulnerable population. And when you apply that over an entire population, the effect can be substantial.”
These issues leave the door open for further research. Future work could seek to replicate the findings in other cohorts, or explore the same issue in a similar cohort experiencing higher exposures, with an eye toward identifying clinically relevant impacts on the kidney—plus connecting the dots between air pollution, renal function, and cardiovascular disease. “I think it’s interesting to look at kidney disease and environmental exposures in general,” Kaufman says, “because kidney disease is becoming an important source of morbidity and mortality as our population ages.”
1. Milojevic A, et al. Short-term effects of air pollution on a range of cardiovascular events in England and Wales: case-crossover analysis of the MINAP database, hospital admissions and mortality. Heart 100(14):1093–1098 (2014), doi: 10.1136/heartjnl-2013-304963.
2. Gansevoort RT, et al. Chronic kidney disease and cardiovascular risk: epidemiology, mechanisms, and prevention. Lancet 382(9889):339–352 (2013), doi: 10.1016/S0140-6736(13)60595-4.
3. Sarnak MJ, et al. Kidney disease as a risk factor for development of cardiovascular disease: a statement from the American Heart Association Councils on Kidney in Cardiovascular Disease, High Blood Pressure Research, Clinical Cardiology, and Epidemiology and Prevention. Hypertension 42(5):1050–1065 (2003), doi: 10.1161/01.HYP.0000102971.85504.7c.
4. NKF. Glomerular Filtration Rate [website]. New York, NY:National Kidney Foundation (2016). Available: https://www.kidney.org/atoz/content/gfr [accessed 24 May 2016].
5. Levey AS, et al. Glomerular filtration rate and albuminuria for detection and staging of acute and chronic kidney disease in adults: a systematic review. JAMA 313(8):837–846 (2015), doi: 10.1001/jama.2015.0602.
6. NKF. KDOQI Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification [website]. New York, NY:National Kidney Foundation (2002). Available: http://www2.kidney.org/professionals/KDOQI/guidelines_ckd/toc.htm [accessed 24 May 2016].
7. Levey AS, et al. Definition and classification of chronic kidney disease: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO). Kidney Int 67(6):2089–2100 (2005), doi: 10.1111/j.1523-1755.2005.00365.x.
8. Mehta AJ, et al. Long-term exposure to ambient fine particulate matter and renal function in older men: the VA Normative Aging Study. Environ Health Perspect 124(9):1353–1360 (2016), doi: 10.1289/ehp.1510269.
9. Bell B, et al. The Normative Aging Study: an interdisciplinary and longitudinal study of health and aging. Int J Aging Hum Dev 3(1):5–17 (1972), doi: 10.2190/GGVP-XLB5-PC3N-EF0G.
10. EPA. NAAQS Table [website]. Washington, DC:U.S. Environmental Protection Agency (updated 29 March 2016). Available: https://www.epa.gov/criteria-air-pollutants/naaqs-table [accessed 24 May 2016].
11. Lue SH, et al. Residential proximity to major roadways and renal function. J Epidemiol Community Health. 67(8):629–634 (2013), doi: 10.1136/jech-2012-202307.