Association of long-term exposure to ambient PM_2.5 with renal function

Objective To evaluate the long-term effects of exposure to atmospheric fine particulate matter (PM_2.5) components (black carbon, ammonium salts, nitrates, organic matter, and sulfates) on renal function.

Methods Based on the data of the China Health and Retirement Longitudinal Study(CHARLS) from 2011 to 2015, a total of 5 696 middle-aged and elderly people were included to explore the individual, interactive, and combined effects of the five PM_2.5 components above on renal function by the Bayesian kernel machine regression(BKMR) method.

Results The incidence of chronic kidney disease during 2011 to 2015 was 5.53%. The posterior inclusion probability(PIP) values of organic matter, black carbon, nitrates, and sulfates were all 1.000, indicating great impact on the estimated glomerular filtration rate (eGFR). When the other four variables were fixed at the 25th, 50th, and 75th percentile, for each increase in organic matter by a quartile, eGFR changed by -9.18 (95% confidence interval CI: -40.16, 21.80), -61.57 (95%CI: -87.50, -35.64), and 10.24 (95%CI: -16.53, 37.01), respectively; for each increase in black carbon by a quartile, the eGFR level increased by 16.67 (95%CI: -12.50, 45.84), 33.30 (95%CI: 10.30, 56.30), and 53.40 (95%CI: 25.00, 81.80), respectively; eGFR was negatively correlated with sulfates, and for each increase in sulfates by a quartile, the changes were -89.83 (95%CI: -161.17, -18.47), -73.28 (95%CI: -102.49, -44.47), and -22.76 (95%CI: -91.42, 45.9), respectively. The combined effect of the PM_2.5 components was generally negatively correlated with eGFR.

Conclusion Organic matter exposure alone is associated with decreased eGFR levels in middle-aged and elderly people. PM_2.5 mixture has a negative correlation with eGFR, with a positive combined effect on the risk of chronic kidney disease.