title: Association of biomarkers of systemic inflammation with organic components and source tracers in quasi-ultrafine particles.
abstract: BACKGROUND
  Evidence is needed regarding the air pollutant components and their sources responsible for associations between particle mass concentrations and human cardiovascular outcomes. We previously found associations between circulating biomarkers of inflammation and mass concentrations of quasi-ultrafine particles <or= 0.25 microm in aerodynamic diameter (PM0.25) in a panel cohort study of 60 elderly subjects with coronary artery disease living in the Los Angeles Basin.
  
  
  OBJECTIVE
  We reassessed biomarker associations with PM0.25 using new particle composition data.
  
  
  METHODS
  Weekly biomarkers of inflammation were plasma interleukin-6 (IL-6) and soluble tumor necrosis factor-alpha receptor II (sTNF-RII) (n = 578). Exposures included indoor and outdoor community organic PM0.25 constituents [polycyclic aromatic hydrocarbons (PAHs), hopanes, n-alkanes, organic acids, water-soluble organic carbon, and transition metals]. We analyzed the relation between biomarkers and exposures with mixed-effects models adjusted for potential confounders.
  
  
  RESULTS
  Indoor and outdoor PAHs (low-, medium-, and high-molecular-weight PAHs), followed by hopanes (vehicle emissions tracer), were positively associated with biomarkers, but other organic components and transition metals were not. sTNF-RII increased by 135 pg/mL [95% confidence interval (CI), 45-225 pg/mL], and IL-6 increased by 0.27 pg/mL (95% CI, 0.10-0.44 pg/mL) per interquartile range increase of 0.56 ng/m3 outdoor total PAHs. Two-pollutant models of PM0.25 with PAHs showed that nominal associations of IL-6 and sTNF-RII with PM0.25 mass were completely confounded by PAHs. Vehicular emission sources estimated from chemical mass balance models were strongly correlated with PAHs (R = 0.71).
  
  
  CONCLUSIONS
  Traffic emission sources of organic chemicals represented by PAHs are associated with increased systemic inflammation and explain associations with quasi-ultrafine particle mass.
authors.affiliation: Department of Epidemiology, School of Medicine, University of California-Irvine, Irvine, California 92617-7555, USA. rdelfino@uci.edu
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Delfino
authors.forename: Norbert
authors.initials: N
authors.lastname: Staimer
authors.forename: Thomas
authors.initials: T
authors.lastname: Tjoa
authors.forename: Mohammad
authors.initials: M
authors.lastname: Arhami
authors.forename: Andrea
authors.initials: A
authors.lastname: Polidori
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gillen
authors.forename: Michael T
authors.initials: MT
authors.lastname: Kleinman
authors.forename: James J
authors.initials: JJ
authors.lastname: Schauer
authors.forename: Constantinos
authors.initials: C
authors.lastname: Sioutas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood*; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000175:diagnosis*; D015850:Interleukin-6 / Q000097:blood; D008137:Longitudinal Studies; D015141:Los Angeles; D008297:Male; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000097:blood; D014315:Triterpenes / Q000032:analysis; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D047889:Receptors, Tumor Necrosis Factor, Type II; D014315:Triterpenes; D001335:Vehicle Emissions; C025206:hopane