Environmental Engineering Reference
In-Depth Information
emphasis has (rightly) been placed on exposure by inhalation. More recently,
however, emphasis has been put on dermal exposure and exposure by ingestion.
For nanomaterials, given their mobility and potential for translocation, it is highly
appropriate to consider these other routes. The various exposure scenarios are
discussed in detail in Chapter 8 .
1.15
Detection and Characterization of Nanomaterials
To assess the risk posed by nanomaterials, it is essential to be able to detect,
measure and characterize them in different media (air, soil and water and toxicity
test media). Properties that are important for the characterization of nanomaterials
include, but are not limited to, concentration, size and size distribution, molar mass,
surface area, state of dispersion/agglomeration, composition, structure, surface
charge, oxidation state, solubility, reactivity and stability (Powers et al. , 2006, 2007 ).
Figure 1.5 shows an example of such a characterization of iron oxide nanoparticles
(Baalousha et al. , 2008b), which shows that the characterization of nanoparticles is
an extensive laborious process, demanding the use of several techniques in parallel
in order to achieve a high degree of accuracy and reliability. To date few quantita-
tive analytical tools for measuring nanomaterials in natural systems are available,
which results in a serious lack of information about their occurrence in the environ-
ment (Nowack and Bucheli, 2007).
There are many challenges for the detection and characterization of nanomateri-
als, including their small size and the need to differentiate the material of interest
from those similarly sized natural materials, the need for sensitive and specifi c
techniques to measure the required metrics (size, number and surface area), the
need to measure nanomaterials properties in several media and the need to measure
several properties in parallel. All current measuring methods and techniques fall
some way short of addressing these requirements.
In addition, the diversity of nanomaterials and their properties make their iden-
tifi cation and characterization a diffi cult task. Furthermore, the interaction of nano-
materials with the natural environmental or biological components provides an
additional complexity to the system and so a signifi cant analytical challenge. The
challenges, methods and tools to characterize nanomaterials is discussed in detail
in Chapter 6 .
1.16
Issues to be Addressed
The risks and impacts of nanomaterials in the environment and for human and
ecological health are still poorly understood and extensive further work is required.
Some priorities to be addressed are given below.
1.16.1
Nomenclature
Formalized, standard terminology for nanotechnology is only starting to become
available but is necessary to make progress. Nanotechnology has been defi ned in
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