Environmental Engineering Reference
In-Depth Information
were analyzed by ANOVA with Sheffe's post-test correction or t-test for single
comparisons at a signifi cance level of p < 0.05. Rats treated with 2.5 mg extract
(8.33 mg extract/ml saline) of TSP from 1986 and 1988 (steel mill operating) devel-
oped acute lung injury characterized by increases in BALF indicators of response.
Response to treatment with the same dose of the 1987 extract was not different from
controls. Instillation of 0.25 or 1.0 mg extract from the 1986 PM extract produced
increases in some BALF parameters (LDH, total cells and neutrophils) that were
signifi cantly greater than controls. Instillation with 5.0 mg/rat of the 1987 (steel mill
closed) extract produced a signifi cant increase in LDH, total protein, total BAL cells
and neutrophils compared to saline controls.
In a related study, Molinelli et al. (
2002
) used a chelating agent to further exam-
ine the role of acid-extractable metals (Table
7
) in the toxicity of PM collected from
the Utah Valley in the winter of 1982 on Sprague Dawley rats exposed
in vivo
, and
on human airway epithelial cell (BEAS-2B) cultures. Rats instilled with 1,000
g of
extract, Chelex-treated extract, and Chelex-treated extract with metals added back
all showed signifi cant increases in BALF proteins and LDH. BEAS-2B cells were
incubated with 100
ʼ
ʼ
L of PM extract at concentrations of 0, 62.5, 125, 250, 500 or
1,000
g/mL, Chelex-treated PM extract, or Chelex-treated PM extract with metals
added back to concentrations in untreated extract, or solutions of metals. Chelex
decreased the mass of, but did not entirely remove Fe, Ni, V, Cu, Zn, Mn, and Pb.
Extract concentrations greater than 125
ʼ
g/mL increased IL-8 levels in the cell cul-
tures. IL-8 production was not signifi cantly increased in cultures incubated with
Chelex-treated, Chelex-treated-with-metals, and metals-only groups compared to
the controls.
ʼ
Ambient PM from Regional Airsheds
In one earlier animal study, Costa and Dreher (
1997
) used PM samples from three
emission sources, including Domestic Oil Fly Ash (DOFA); ROFA; and Coal Fly
Ash (CFA); and four ambient airsheds: St. Louis, MO; Washington, DC; Dusseldorf,
Germany; and Ottawa, Canada, to investigate the role of bioavailable (extractable in
1 M HCl) transition metals (Cu, Fe, Ni, V, and Zn) in a rat model of adverse cardio-
pulmonary outcomes. Healthy Sprague Dawley rats were instilled with 2.5 mg
(equal dose by mass to yield a total metal content of 46
g/dose) of the PM extracts
and sacrifi ced 24 or 96 h later. When the mass from each of the seven PM sources
was normalized to a dose of 46
ʼ
g total metals/rat, the BALF cellular responses
were similar for all PM samples, suggesting that toxicity was related to the bioavail-
ability of the constituent transition metals. Rats with monocrotaline-induced pulmo-
nary hypertension instilled with the metal-rich ROFA had signifi cant higher
mortality than healthy rats instilled with ROFA. It should be noted that the PM
samples used in these experiments had been in storage from 3 to 15 years, and there
was considerable variability in the acid-extractable concentrations of metals
(Table
6
) in the seven different sources.
In four studies (Gavett et al. (
2003
), Gerlofs-Nijland et al. (
2009
), Happo et al.
(
2008
), and Schins et al. (
2004b
)), the toxicity of metals in ambient PM from various
ʼ
Search WWH ::
Custom Search