Adverse Effects of fine particulate matter on human kidney functioning: a systematic review

Abstract

Background: Ambient fine particulate matter (PM < 2.5 μm, PM_2.5) is gaining increasing attention as an environmental risk factor for health. The kidneys are considered a particularly vulnerable target to the toxic effects that PM_2.5 exerts. Alteration of kidney function may lead to a disrupted homeostasis, affecting disparate tissues in the body. This review intends to summarize all relevant knowledge published between January 2000 and December 2021 on the effects of ambient PM_2.5 and the adverse effects on kidney function in adults (≥ 18 years).

Results and discussion: Studies published in peer-reviewed journals, written in English, regarding the effects of PM_2.5 on kidney function and the development and/or exacerbation of kidney disease(s) were included. Of the 587 nonduplicate studies evaluated, 40 were included, comprising of studies on healthy or diagnosed with pre-existing disease (sub)populations. Most of the studies were cohort studies (n = 27), followed by 10 cross-sectional, 1 ecological and 2 time-series studies. One longitudinal study was considered intermediate risk of bias, the other included studies were considered low risk of bias. A large portion of the studies (n = 36) showed that PM_2.5 exposure worsened kidney outcome(s) investigated; however, some studies show contradictory results. Measurement of the estimated glomerular filtration rate, for instance, was found to be positively associated (n = 8) as well as negatively associated (n = 4) with PM_2.5.

Limitations and conclusion: The main limitations of the included studies include residual confounding (e.g., smoking) and lack of individual exposure levels. The majority of included studies focused on specific subpopulations, which may limit generalizability. Evidence of the detrimental effects that ambient PM_2.5 may exert on kidney function is emerging. However, further investigations are required to determine how and to what extent air pollution, specifically PM_2.5, exerts adverse effects on the kidney and alters its function.

Registration: The systematic review protocol was submitted and published by the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020175615 ).

Keywords: Air pollution; Fine particulate matter; Kidney; Kidney disease; PM2.5.

Fig. 1

Overview of the data selection process. Records either identified through database searches of PubMed and Scopus (n = 737) from January 1st, 2000 until December 20th, 2021, and records identified through bibliographies of reviews (n = 2). After checking for and removal of duplicates, records were screened for eligibility according to the a priori defined criteria, that resulted in n = 70 eligible records. Next, full-text articles were screened for a second time against the eligibility criteria. The final selection (n = 40) consisted of human studies focusing on ambient PM exposure and addressing: (i) clinical measurements of eGFR (n = 8), (ii) general kidney function through changes in biomarkers (n = 2), and (iii) glomerular diseases (n = 4). The remaining articles focused on persons with a diagnosis of diabetes mellitus where kidney function declined (n = 2), CKD (n = 14), ESRD (n = 2), renal failure (n = 4), and kidney transplant outcome (n = 4). Abbreviations: CKD, chronic kidney disease; ESRD, end-stage renal disease; eGFR, estimated glomerular filtration rate; PM_2.5, fine particulate matter (< 2.5 microns)

Fig. 2

Schematic overview of the distribution of articles on kidney disease (outcomes) in the systematic review. Eligible articles (n = 40) were divided into the corresponding disease outcomes. Included studies focused on (i) clinical measurements of eGFR (n = 8), (ii) biomarkers to evaluate kidney function following PM exposure (n = 2), (iii) glomerular diseases (n = 4), (iv) diabetes mellitus as a driver to kidney function decline (n = 2), (v) CKD (n = 14), (vi) ESRD (n = 2), (vii) kidney failure (n = 4), and (viii) kidney transplantation (n = 4). These numbers of articles for the listed classes of kidney disease (outcomes) do not necessarily correspond with the main text, as for each class, the most representative articles were considered. Abbreviations: CKD, chronic kidney disease; ESRD, end-stage renal disease; eGFR, estimated glomerular filtration rate; PM_2.5, fine particulate matter (< 2.5 microns)