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Zhang X, Staimer N, Gillen DL, Tjoa T, Schauer JJ, Shafer MM, Hasheminassab S, Pakbin P, Vaziri ND, Sioutas C, Delfino RJ. Associations of oxidative stress and inflammatory biomarkers with chemically-characterized air pollutant exposures in an elderly cohort. ENVIRONMENTAL RESEARCH 2016; 150:306-319. [PMID: 27336235 PMCID: PMC5003670 DOI: 10.1016/j.envres.2016.06.019] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/18/2016] [Accepted: 06/10/2016] [Indexed: 05/12/2023]
Abstract
BACKGROUND Exposure to air pollution has been associated with cardiorespiratory morbidity and mortality. However, the chemical constituents and pollution sources underlying these associations remain unclear. METHOD We conducted a cohort panel study involving 97 elderly subjects living in the Los Angeles metropolitan area. Airway and circulating biomarkers of oxidative stress and inflammation were measured weekly over 12 weeks and included, exhaled breath condensate malondialdehyde (EBC MDA), fractional exhaled nitric oxide (FeNO), plasma oxidized low-density lipoprotein (oxLDL), and plasma interleukin-6 (IL-6). Exposures included 7-day personal nitrogen oxides (NOx), daily criteria-pollutant data, five-day average particulate matter (PM) measured in three size-fractions and characterized by chemical components including transition metals, and in vitro PM oxidative potential (dithiothreitol and macrophage reactive oxygen species). Associations between biomarkers and pollutants were assessed using linear mixed effects regression models. RESULTS We found significant positive associations of airway oxidative stress and inflammation with traffic-related air pollutants, ultrafine particles and transition metals. Positive but nonsignificant associations were observed with PM oxidative potential. The strongest associations were observed among PM variables in the ultrafine range (PM <0.18µm). It was estimated that an interquartile increase in 5-day average ultrafine polycyclic aromatic hydrocarbons was associated with a 6.3% (95% CI: 1.1%, 11.6%) increase in EBC MDA and 6.7% (95% CI: 3.4%, 10.2%) increase in FeNO. In addition, positive but nonsignificant associations were observed between oxLDL and traffic-related pollutants, ultrafine particles and transition metals while plasma IL-6 was positively associated with 1-day average traffic-related pollutants. CONCLUSION Our results suggest that exposure to pollutants with high oxidative potential (traffic-related pollutants, ultrafine particles, and transition metals) may lead to increased airway oxidative stress and inflammation in elderly adults. This observation was less clear with circulating biomarkers.
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Affiliation(s)
- Xian Zhang
- Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA
| | - Norbert Staimer
- Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA
| | - Daniel L Gillen
- Department of Statistics, School of Information and Computer Sciences, University of California, Irvine, CA, USA
| | - Tomas Tjoa
- Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA
| | - James J Schauer
- University of Wisconsin-Madison, Environmental Chemistry and Technology Program, Madison, WI, USA
| | - Martin M Shafer
- University of Wisconsin-Madison, Environmental Chemistry and Technology Program, Madison, WI, USA
| | - Sina Hasheminassab
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Payam Pakbin
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Nosratola D Vaziri
- Division of Nephrology and Hypertension, Department of Medicine, School of Medicine, University of California, Irvine, CA, USA
| | - Constantinos Sioutas
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Ralph J Delfino
- Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA.
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