Environmental Engineering Reference
In-Depth Information
It is understandable that in such studies we try to simplify measurements and averaging data.
But if we cannot assess the dose directly, measuring the surrogate physical value instead and using
averaging data, we have to pay the price for this, that is, try to assess the loss in the reliability in the
risk assessment.
As it is clear from the dosimetric road map for nanoaerosols, presented in the following, the
problem of the dose and risk assessment for nanoaerosols is even more complicated than for
radiation, including radon and its progeny. So, we should avoid the errors that were made in the
case of radon.
16.1
NANOAEROSOLS: DOSIMETRIC ROAD MAP
16.1.1 i
ntroduction
The nanotechnology industry is rapidly growing with promises of substantial beneits that will have
signiicant global, economic, and scientiic impacts, applicable to a whole host of areas from engi-
neering and electronics to environmental remediation and medical healthcare. However, at present
there is a growing concern over the safety of nanomaterials with respect to occupational, consumer,
and environmental exposures.
Particularly, information on nanomaterial exposure, dosimetry, risk assessment, and health
effect is negligible. Furthermore, the gap between these two tendencies widens at an alarming rate.
According to Kulinowski (2009), “there's a lot more data now than there was back in the early
days. Between 2001 and 2008 (the last year for which complete data are available), the annual
NanoEHS publication rate grew between 20%-120% per year with over 3600 individual papers.”
Unfortunately, however, “it becomes equally dificult to say that all these data are conclusive.
A recent analysis found that much of the “nanotoxicology” research is done
in vitro
, focusing on
acute toxicity and mortality induced by native nanoparticles, with limited relevance to human health
or environmental impacts and little attention to consumer products.”
Up to the present time, publicly available quantitative data related to dosimetry of nanomaterials,
and particularly aerosolized nanoparticles, are very dificult to ind.
And what is even more important is that there is a lack of information in scientiic literature on the
development of strategy in the study of sequence of physical parameters, each of which is extremely
important for the assessment of the main cause of the effect in the case of nanoparticles—dose.
In this chapter we present and discuss the dosimetric road map, that is, the consequence of par-
ticular steps, which we need to take in order to assess the dose—main cause of biological effect
from nanoaerosols.
16.1.2 n
anoParticle
In general, a particle is deined as a small object that behaves as a whole unit in terms of its transport
and properties. It is further classiied according to size: In terms of diameter, ine particles cover
a range between 100 and 2500 nm, while ultraine particles, on the other hand, are sized between
1 and 100 nm. Similar to ultraine particles, nanoparticles are sized between 1 and 100 nm, though
the size limitation can be restricted to two dimensions.
Nanoparticles may or may not exhibit size-related properties that differ signiicantly from those
observed in ine particles or bulk materials.
There is no accepted international deinition of a nanoparticle, but one given in the new PAS71
(the British Standards Institution, BSI) document developed in the United Kingdom is “particle with
one or more dimensions at the nanoscale.”
Correspondingly, the nanoscale is deined as “having one or more dimensions of order of 100 nm
or less.” There is a note associated with this deinition: “Novel properties that differentiate nanopar-
ticles from the bulk material typically develop at a critical length scale of under 100 nm.”
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