Susceptible
Population: Clues to Potential Causal Component Mixtures and Mechanisms
http://www.ehponline.org/docs/2009/0800194/abstract.pdf
Ralph J. Delfino,1 Norbert Staimer,1 Thomas Tjoa,1 Daniel L. Gillen,2 Andrea
Polidori,3
Mohammad Arhami,3 Micheal T. Kleinman,4 Nosratola D. Vaziri,5 John
Longhurst,5
Constantinos Sioutas.3
ABSTRACT
Background: Mechanisms involving oxidative stress and inflammation have been
proposed
to explain associations of ambient air pollution with cardiovascular
morbidity and mortality.
Experimental evidence suggests organic components and ultrafine particles
are important.
Methods: We conducted a panel study of 60 elderly subjects with coronary
artery disease
living in retirement communities within the Los Angeles air basin. Weekly
biomarkers of
inflammation included plasma interleukin-6 (IL-6), tumor necrosis factor-?
and receptor
(sTNF-RII), soluble platelet selectin (sP-selectin), and C-reactive protein
(CRP).
Biomarkers of erythrocyte antioxidant activity included glutathione
peroxidase-1 and
superoxide dismutase. Exposures included outdoor home daily particle mass
(PM0.25,
PM0.25-2.5, PM2.5-10), and hourly elemental and black carbon (EC-BC),
estimated primary and
secondary organic carbon (OCpri, SOC), particle number (PN), CO, and
NOx-NO2. We
analyzed the relation of biomarkers to exposures with mixed effects models
adjusted for
potential confounders.
Results: Primary combustion markers (EC-BC, OCpri, CO, NOx-NO2), but not
SOC, were
positively associated with inflammatory biomarkers and inversely associated
with
erythrocyte antioxidant enzymes (N=578). PN and PM0.25 were more strongly
associated
with biomarkers than PM0.25-2.5. Associations for all exposures were
stronger during cooler
periods when only OCpri, PN, and NOx were higher. We found weaker
associations with
statin (sTNF-RII, CRP) and clopidogrel use (sP-selectin).
Conclusions: Traffic-related air pollutants are associated with increased
systemic
inflammation, increased platelet activation, and decreased erythrocyte
antioxidant enzyme
activity, which may be partly behind air pollutant-related increases in
systemic inflammation.
Differences in association by particle size, OC fraction, and seasonal
period suggest
components carried by ultrafine particles are important.
