Respiratory and Cardiovascular Effects of Metals in Ambient Particulate Matter: A Critical Review - Reviews of Environmental Contamination and Toxicology - page 137

2.3 Toxicology

We searched the toxicology literature for in vivo and in vitro studies, including
human studies that were designed to elucidate the role of PM-associated metals in
the respiratory and cardiovascular health effects most frequently reported in epide-
miologic studies. We selected studies that provided data on metal exposures from a
source of ambient PM, such as archived particulates from regional air monitors,
concentrated ambient particles (CAPs), or residual oil fl y ash (ROFA). In several
studies, laboratory animals or cell cultures were treated with solutions of the major
metal constituents that had been identifi ed in ambient PM sources. The in vitro stud-
ies summarized in this review were often designed to reveal the mechanisms by
which PM-associated metals may contribute to adverse health effects.
The in vivo studies summarized herein utilized different dosing routes (e.g.,
inhalation, intratracheal instillation), animal models (e.g., mouse, rat, dog, human),
dosage levels, and often expressed doses in different units. To allow comparison
across studies, when suffi cient information was available, we recalculated all dos-
ages on a mass per body weight basis. For reference to typical human daily dosages,
we used the annual mean concentrations of our target metals in the STN 2008 data
(Table 1 ). We assumed a daily breathing rate of 10 m 3 and a human body weight of

Table 1 Mean annual concentrations of PM 2.5 and transition metals in ambient air in the U.S. as
reported by the Speciation Trends Network (STN 2008) and Interagency Monitoring of Protected
Visual Environments (IMPROVE 2006)

STN 2008 IMPROVE 2006

Ratio
means, STN/
IMPROVE

Standard
error

Fraction
of PM 2.5

Standard
error

Fraction
of PM 2.5 Analyte N Mean N Mean

Particulate Matter 2.5 — ʼ g/m 3
PM 2.5 13,990 12.5 0.67 - 19,272 5.4 0.037 - 2.3

Target Metals—ng /m 3
As 13,607 0.8 0.01 0.006% 19,002 0.2 0.003 0.004% 4.0
Cr 13,607 2.3 0.23 0.018% 18,861 0.1 0.003 0.002% 23
Cu 13,702 5.4 0.11 0.043% 19,019 0.8 0.014 0.015% 6.7
Fe 13,702 94 2.21 0.752% 19,094 46 0.547 0.852% 2.1
Mn 13,607 3.0 0.18 0.024% 19,088 1.3 0.018 0.024% 2.3
Ni 13,607 1.3 0.09 0.010% 18,956 0.3 0.008 0.006% 4.3
Se 13,607 0.5 0.01 0.004% 18,838 0.4 0.005 0.007% 1.3
Ti 13,702 2.5 0.05 0.020% 19,079 3.9 0.05 0.072% 0.6
V 13,702 1.1 0.02 0.009% 18,918 0.5 0.007 0.009% 2.3
Zn 13,702 14 0.28 0.112% 19,093 4.3 0.081 0.080% 3.2
a STN Detection Limits (US EPA 2010b): As (2.5), Cr (1.6), Cu (1.4), Fe (2.0), Mn (2.3), Ni (1.3),
Se (2.1), Ti (2.1), V (1.5), Zn (1.5)
b IMPROVE Detection Limits (US EPA 2010a): As (0.094), Cr (0.028), Cu (0.043), Fe (0.039), Mn
(0.026), Ni (0.059), Se (0.026), Ti (0.051), V (0.034), Zn (0.039)