Exposure to Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 345

that the human factor element will be even more critical than for larger particles
(e.g. particles greater than 500 nm). In this case, it is quite likely that SPE will be
less effective against nanoparticles than against larger particles. It is also quite likely
that direct penetration of nanoparticles through the material from which the pro-
tective clothing is made will also be higher than for larger particles. Preliminary
work published by the NANOSAFE project indicates that this is indeed the case.
Few details of their experimental approach are available but their recommendation
is that penetration is higher and that two sets of gloves should be worn (NANOSAFE,
2008 ).
It has not been possible to identify any relevant research work which has looked
at the impact of nanoparticles on the probability of failure of SPE due to human
factors. No information on these issues was available from any of the manufac-
turer' s websites.

8.4.4 Ingestion Exposure

Exposure by ingestion in the workplace is currently not well understood. It is con-
sidered that ingestion exposure in the workplace results primarily from hand-to-
mouth contact. It follows that strategies that tend to reduce dermal exposure in the
workplace will also tend to reduce exposure by ingestion. The converse of this is
also true. At this point in time no relevant research has been identifi ed that has
successfully quantifi es exposure to nanoparticles by ingestion in the workplace or
the effectiveness of strategies to reduce this exposure.

8.5 Discussion

The development and application of nanoparticles represents a major portion of
nanotechnology activity and the number of nanoparticle products continues to
grow. The purpose of producing these new materials and products is that their
behaviour is expected (and has been demonstrated) to be different in the nanome-
tre scale than in the microscale. Nanoparticles are produced using a wide range of
synthesis methods by university and other research groups, small emerging compa-
nies and by established major international organisations.
The main processes by which nanoparticles are manufactured are gas phase
synthesis, vapour deposition, colloidal methods and attrition methods. Although
these processes are capable of producing materials with strikingly different proper-
ties from bulk forms of the same material, from an occupational hygiene perspec-
tive the processes themselves are not dissimilar to conventional well established
chemical and engineering processes. In principle, all of these production methods
may give rise to exposure by inhalation, through the skin and by ingestion.
Exposure by inhalation caused by direct leakage of nanoparticles into the work-
place air during synthesis only seems possible in gas phase processes. In vapour
deposition, particle growth is on a substrate and in the colloidal and attrition
methods particle formation is in the liquid phase, therefore aerosols will not be
formed during synthesis. However, for all production methods, product recovery