Biomedical Engineering Reference
In-Depth Information
Section 11.3.3.2. Mueller and Nowack
84
provide an interesting model of multi-
media transfer between environmental compartments for nanosilver.
Human intake fractions:
Specifically, we aim to model the fate and expo-
sure from the emission source to the intake dose nanoparticulate intake frac-
tion, as defined by Bennett et al.,
124
characterizing the fate and exposure of
both organics and inorganics, as well as fine particles.
125,126
Taking fullerene
as an example, we have built on the work of Maddalena et al.
109
and adapted
the IMPACT 2002 multimedia model
127
to the nanoparticle properties pro-
posed by Abraham et al.
108
Figure 11.10 compares the intake fraction of fullerenes to that of various per-
sistent organic chemicals (POPs). It is interesting to note the predicted reduction
in absorption for POPs at high
K
ow
, linked to low bioaccumulation in animals
128
and possibly reflected in the low absorption rate for nanomaterials such fuller-
enes (2% according to Obersdörster et al.
129
). Such multimedia models can also
provide the transfer factors to, and fate factor or residence time in water and soil,
as defined in Equation 11.3. For intake fraction emitted indoors, the approach
proposed by Wenger et al.
130
enables us to account for adsorption on the indoor
surfaces, provided that the substance vapor pressure is given. It should, how-
ever, be verified whether the extrapolation between vapor pressure and parti-
tion coefficient between air and wall at the wall surface holds for nanoparticles.
From intake to uptake fraction:
For ultrafine and eventually nanoparticles,
Humbert
131
has proposed to determine the uptake fraction, which expresses
the ratio of uptake in the respiratory tract (i.e., the deposition in the respiratory
tract) to emission rate (in terms of mass, surface area, or number of particles)
Intake fraction for emissions to freshwater—
% per route of exposure (left) and total iF (right scale)
100%
1.E-01
6.8
90%
7.1
6.8
6.8
7.4
7.5
7.6
80%
1.E-02
6.4
7.5
70%
6.0
7.9
60%
50%
1.E-03
8.3
12.6
40%
8.7
3.1
\
30%
1.E-04
1.4
20%
10%
0%
1.E-05
Watering
Vegetationing
Fish indirecting
Meat indirecting
Milk indirecting
TOTAL
FIGURE 11.10
Intake fractions for Buckminster fullerenes compared with organic pollutants. (Adapted from
Maddalena, R.L. et al., Hazard assessment and sensitivity analysis for Buckminster fullerene in
the environment.
Platform Presentation 681, Proceedings of the SETAC NA 2005 Symposium,
20 05.)
