Association of biomarkers of systemic inflammation with organic components and source tracers in quasi-ultrafine particles.
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.
Delfino
Ralph J
RJ
Department of Epidemiology, School of Medicine, University of California-Irvine, Irvine, California 92617-7555, USA. rdelfino@uci.edu
Staimer
Norbert
N
Tjoa
Thomas
T
Arhami
Mohammad
M
Polidori
Andrea
A
Gillen
Daniel L
DL
Kleinman
Michael T
MT
Schauer
James J
JJ
Sioutas
Constantinos
C
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*
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