Environmental Engineering Reference
In-Depth Information
taBlE 30.1
(
Continued
)
Applications in
nanotoxicology
Assay
Purposes
Cell line
References
glutathione reduced assay
Cell signaling
activity
CdO
Rat liver cells BRL 3A
[46]
TiO
2
Human epidermal cells
[47]
MoO
3
A431
[54]
Metallic Al
Colloidal Ag
Caspase activation kits
Cell apoptosis
Fe
3
O
4
Human fibroblasts hTERT-BJ1
[55]
TiO
2
Kidney cells LLC-PK1
[56]
Hepatocarcinoma cells
Hep-g2
[57]
[58]
Real-time cell electronic
sensing system
Cytotoxicity
TiO
2
NK 92 Cells
[59]
gold nanoparticles
Breast cancer cells MdA-231-B
and MCF-7
[60]
Human alveolar epithelial cells
L-132
Human glioblastoma cells T98g
Human primary fibroblast cells
AgO-1522B
Electron microscopy
Nanoparticle shape
and intracellular
localization
CNT
Human epidermal keratinocytes
(HEK)
[26]
TiO
2
Neural stem cells
[61]
CeO
Bronchial epithelial cells
[62]
Fe
3
O
4
[55]
[63]
a
OECd and EvCAM guidelines are summarized in Ref. [43].
In this way, cytotoxicity tests can be used to predict the acute toxicity of NMs, and 2d and 3d assays are used to address their
specific localization. It is important to mention that in all colorimetric assays—in addition to counting the cell number—it is
very important to measure any specific damage, and not necessarily only total death, because if there is any inhibition of growth
during the experiment that is not caused directly by the application of nanoparticles, this decrease in cell growth could be esti-
mated as a false positive. Besides, all colorimetric assays have demonstrated that they are liable to the interaction between dye
agents and NMs, and it is very difficult to wash out the remaining dye [28, 43]. At this moment, 2d and 3d systems such as light
and electron microscopy, and real-time analyses by impedance or platting efficiency assays appear to be the most reliable sys-
tems because of the elimination of additional chemical treatments and the constant monitoring of the culture [43, 50, 64, 60, 65].
30.2.4
In Vivo
assays
Living systems are potentially exposed to NMs through ingestion, ocular, dermal, or inhalation pathways. This exposure can occur
when environmental pollutans are present in air, water, or soil. We do not know the effects of many of these materials on our health,
and if the
in vitro
assays do not satisfactorily demonstrate the potential effects, then testing in an
in vivo
model is needed. In order
to select an appropriate and representative
in vivo
model it is important to consider the NMs' route of exposure. For example, for
the oral route, although several mammalian test species may be used, the rat is the preferred species. In the case of dermal
exposure, the most common animal models are the rat, the rabbit, and the guinea pig, but the albino rabbit is preferred because of
its size, ease of handling, skin permeability, and extensive database. Commonly used laboratory strains must be employed. If a
species other than rats, rabbits, or guinea pigs is used, the tester must provide justification and reasoning for its selection [66].
Using a variety of techniques, typical
in vivo
assessments include the determination of physiological localization and the
concentration of material in specific tissues, rate of excretion, macroscopic tissue analysis, and organism toxicity [67].
Short-term (“acute”) tests are generally used first, with observations of organism survival being the most common
measurement of effect. Longer-term (“chronic”) tests (with observation of sublethal effects on organism growth or reproduction
being the most common measurement of effect) are then used when results from short-term tests combined with large safety
factors suggest that there may be risks to the environment [29].
