title: Associations of oxidative stress and inflammatory biomarkers with chemically-characterized air pollutant exposures in an elderly cohort.
abstract: Exposure to air pollution has been associated with cardiorespiratory morbidity and mortality. However, the chemical constituents and pollution sources underlying these associations remain unclear.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA.
authors.forename: Norbert
authors.initials: N
authors.lastname: Staimer
authors.affiliation: Department of Statistics, School of Information and Computer Sciences, University of California, Irvine, CA, USA.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gillen
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA.
authors.forename: Tomas
authors.initials: T
authors.lastname: Tjoa
authors.affiliation: University of Wisconsin-Madison, Environmental Chemistry and Technology Program, Madison, WI, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Schauer
authors.affiliation: University of Wisconsin-Madison, Environmental Chemistry and Technology Program, Madison, WI, USA.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Shafer
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Sina
authors.initials: S
authors.lastname: Hasheminassab
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Payam
authors.initials: P
authors.lastname: Pakbin
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, School of Medicine, University of California, Irvine, CA, USA.
authors.forename: Nosratola D
authors.initials: ND
authors.lastname: Vaziri
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Sioutas
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, CA, USA. Electronic address: rdelfino@uci.edu.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Delfino
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000097:blood / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D015331:Cohort Studies; D004781:Environmental Exposure; D005260:Female; D005579:Fossil Fuels / Q000633:toxicity*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000453:epidemiology*; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*
chemical_list: D000393:Air Pollutants; D015415:Biomarkers; D005579:Fossil Fuels; D052638:Particulate Matter
keywords: Air pollution; Biomarkers; Inflammation; Oxidative stress; Particulate matter components