Environmental Engineering Reference
In-Depth Information
PM
2.5
, and their components and associated gaseous criteria pollutants (Harvard 6-Cities, American
Cancer Society, U.S. Military Veterans, NHANES III, MESA, Women's Health Initiative [WHI],
and the Southern California Children's Health Study). They also include studies of the effects of
air quality interventions and their health consequences (i.e., Hong Kong S-in-fuel intervention), and
examination of newly available speciation data in relation to available daily mortality data from the
NMMAPS study. The results of these various studies continue to implicate PM
2.5
as a useful index
of excess mortality risk, and many of them, having access to speciation data, implicate transition
metals within the PM
2.5
as being especially likely to be causal factors for the associations.
14.2.5 e
xPosures
oF
H
uMan
v
olunteers
via
i
ntratracHeal
i
nstillation
The only other studies in human volunteers for which component analyses were available involved
administration of PM by IT instillation of particle suspensions.
On the basis that Fe is the most abundant of the transition metals in ambient air, Lay et al. (1998)
and Ghio et al. (1998) instilled ∼5 mg doses containing both soluble and insoluble 2.6 μm Fe particle
agglomerates suspended in saline into the lungs of volunteer subjects to investigate oxidative stress.
BALF samples were collected from 1 to 91 days later. At 1 day, Lay et al. (1998) and Ghio et al. (1998)
reported inlammatory responses. Recent research has suggested that trafic-generated PM can account
for pulmonary effects, with Gent et al. (2009) showing that the motor vehicle source was associated
with a 10%/5 μg
3
increase in wheeze in asthmatic children, while the road dust source was associated
with a 28% increase in shortness of breath. This response is consistent with the indings reported by
Gottipulo et al. (2008) based on the instillation of two kinds of tire dust into the lungs of male WKY
rats in relation to the elemental composition. There were increases in BALF markers of inlammation
and injury, and similar effects were seen for instilled Zn and Cu. Thus, the acute pulmonary effects of
tire dust could be due to the metals (Ghio et al. 1988). reported decreased transferrin concentrations
and increased concentrations of ferritin and lactoferrin. By 4 days, iron homeostasis was normal.
These kinds of tests have proved to be more informative when they were applied to real-world
PM samples that were associated with adverse effects in human populations, such as those from the
Utah Valley, where there was a 14 month-long strike at a steel mill complex. There were signii-
cantly lower rates of mortality and hospital admissions during the strike than in the preceding and
following years (Pope, 1989, 1991; Pope et al., 1992). Analyses of the PM collected on air sampling
ilters during those 3 years indicated that the concentrations of many airborne metal PM compo-
nents were also signiicantly lower during the strike interval than in the preceding and following
years (Frampton et al., 1999; Dye et al., 2001; Ghio and Devlin, 2001). Extracts of metals from
sampling ilters were used to test whether soluble components or ionizable metals, which accounted
for 20% of the PM mass, could be responsible for the adverse health effects.
14.3
REVIEW OF AMBIENT PARTICULATE MATTER STUDIES
IN LABORATORY ANIMALS AND
IN VITRO
14.3.1 i
ntroduction
This review of laboratory animal responses is focused on CAPs inhalation studies and their health
effects, with an emphasis on studies that identify the particle size ranges and components most
closely associated with the observed effects. Lung instillation studies involving PM suspensions
of materials found in ambient air have been covered. Associations between ambient air PM size
fractions and components and human health-related responses in panel and larger-population
studies were presented in Section 14.2, including those indicating responses to chronic exposures.
Studies in animals have not been limited to short-term exposures and acute responses. Section 14.5
compares the effects of chronic exposure in the animal models to those associated with chronic
exposure in the epidemiological studies summarized in Section 14.2.
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