Environmental Engineering Reference
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airsheds in Europe were evaluated, using in vivo rodent models. In the studies
conducted by Gerlofs-Nijland et al. ( 2009 ) and Happo et al. ( 2008 ), the actual metal
concentrations were not given for the various locations, but rather were inferred
from previous studies or were based on the presence of industrial sources.
Gavett et al. ( 2003 ) conducted experiments by using an allergic mouse model to
determine if the metals composition of ambient PM 2.5 could help to explain reports
that children in the industrialized Hettstedt area of eastern Germany have a higher
prevalence of sensitization to common allergens than children in the less industrial-
ized City of Zerbst (Table 7 ). Normal non-allergic Balb/c mice instilled with saline,
or 100
g of either Hettstedt or Zerbst PM. Hettstedt PM 2.5 had signifi cantly
increased BALF protein levels and indicators of epithelial cell injury as compared
to mice instilled with saline). In allergic mice (sensitized with ovalbumin), exposure
to both the Hettstedt and Zerbst PM extracts increased airway response to metha-
choline, with only the Hettstedt PM response being signifi cantly greater than con-
trols. From the transition metal composition of the two PM samples, it is apparent
that the concentrations of As and Mn were similar, the sample from Zerbst had
somewhat higher levels of Fe, Ni and V, and the sample from Hettstedt had much
higher concentrations of Cu and Zn, suggesting that the effects on infl ammatory
markers and allergic airway response may have been related to these two metals.
However, this was not confi rmed by exposing the animals to concentrations of these
metals equivalent to those in the PM samples.
Schins et al. ( 2004b ) evaluated the infl ammatory response to coarse (PM 2.5-10 )
and fi ne (PM 1.0-2.5 ) particulates from a rural area (Borken) and an industrialized area
(Duisburg) in Germany (total of four PM samples, concentrations in Table 6 ). The
hydroxyl-radical generating capability of the PM fractions was determined and
infl ammatory potential evaluated in Wistar rats. Both Duisburg fi ne and Duisburg
coarse PM generated signifi cantly more hydroxyl-radicals than either fraction from
Borken, with the Duisburg coarse PM fraction producing signifi cantly more radicals
than the Duisburg fi ne fraction. This fi nding seems counter-intuitive because the
concentrations of soluble metals in the fi ne PM samples from both locations were
greater than in the coarse fractions. Furthermore, the concentrations of Fe and Ni in
the coarse fraction from the rural area of Borken were more than three times higher
than the concentrations of these metals in the coarse fraction from the industrialized
area of Duisburg. Wistar rats were then instilled with 0.32 mg of aqueous extract
from each of the four PM samples, or saline control, and indicators of infl ammatory
response were evaluated in BALF 18 h after exposure. Coarse PM from both air-
sheds produced changes in some, but not all, infl ammatory markers in BALF that
were signifi cantly different from controls. It should also be noted that the coarse PM
from both locations contained higher levels of endotoxin than did the fi ne fraction.
In the majority of the studies that we reviewed, in which the size fractions were
examined, the fi ne PM fraction typically produced a greater infl ammatory response
than the coarse fraction.
As the authors (Schins et al. 2004b ) acknowledged, the fact that the metal doses
applied to the experimental animals were at least 15-1,100 times higher than a
human would receive from ambient exposure (Table 6 ), and the heterogeneity of the
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