Environmental Engineering Reference
In-Depth Information
In the companion study by Saldiva (
2002
), inhalation exposure to CAPs for both
the normal and bronchitic rats caused variable increases in pulmonary neutrophils
and total BALF cell counts as compared to controls. Many of the rats exposed to
CAPs developed acute pulmonary infl ammation. Signifi cant overall associations
were found for CAPs, V, and bromine due to changes in normal rats; the changes in
bronchitic rats were not signifi cantly associated with V. The authors suggested that
because the bronchitic rats had more infl ammatory changes than the normal animals
as a result of their disease status, further change was diffi cult to detect, and therefore
was likely underestimated.
Kodavanti et al. (
2005
) described multiple exposure studies, in which the
responses of spontaneously hypertensive (SH) and normo-tensive Wistar Kyoto
(WKY) exposed to CAPs (concentration factor from 40 to 60 times ambient) were
compared. Concentrations of CAPs and individual water-soluble metals were highly
variable. Ventilatory parameters were measured during six repeat studies of 4 h/day
for 1-day exposures in late autumn 2000, and seven repeat studies of 4 h/day for
2-day exposures in late summer/early autumn 2001. At necropsy, all hematologic
parameters evaluated were higher in SH than WKY rats, although none of the bio-
chemical and infl ammatory parameters showed a consistent change. There were no
consistent relationships between metals in CAPs and strain-specifi c changes in the
responses being measured.
Lippmann et al. (
2006
) investigated the effects of metals in New York City CAPs
(concentration factor 10 times ambient levels) on cardiovascular responses in ath-
erosclerotic ApoE−/− mice fed a high fat diet and exposed for 6 h/day, 5 days/week,
for 6 months (summer through fall). In this study, Ni, but not V was signifi cantly
associated with changes in cardiac function. The peak Ni concentration in CAPs
was 175 ng/m
3
, with the average concentration being 26 ng/m
3
. To put this in per-
spective, the long-term average concentration of Ni across the U.S. is 1.9 ng/m
3
and
in New York City it is 19 ng/m
3
.
Critical Comments on In Vivo Studies with CAPs
In summary, the studies we reviewed, in which animals were exposed to CAPs by
inhalation were reasonably analogous to the human condition, only at somewhat
exaggerated concentrations of constituents. It should be considered that the transi-
tion metals of interest comprise a relatively minor fraction of ambient PM, and
would be expected to comprise a similarly minor fraction of CAPs. The contribu-
tions of the other constituents (e.g., endotoxin) in ambient PM and subsequently
CAPs are not well accounted for in these studies.
In Vivo Exposures to Metals in Residual Oil Fly Ash (ROFA)
The burning of heavy oils in boilers and electrical power generating plants produces
particulates that are enriched with metals. The resulting ash particulates contribute to
ambient PM in some regions of the U.S. and internationally. Relative to other emission
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