Field and Laboratory Measurements Related to Occupational and Consumer Exposures - Safety of Nanomaterials along Their Lifecycle - page 279

by VTT Technical Research Centre of Finland (from where it is commercially avail-
able) (Lyyränen et al. 2009) and the Mini Particle Sampler developed by INERIS and
distributed by EcoMesure (R'mili et al. 2013). An electrostatic precipitator (EP) col-
lects the charged particles on a sample carrier, for example, TEM grid, by employ-
ing a strong electric field (5-10 kV) between two parallel plates (electrodes). Either
the natural particle charge distribution or a corona discharger, to enhance the charge
level, is used in these devices. Within the NANODEVICE project, a “plug and play”
EP has been developed for relatively short sampling periods in the range of 20-400 nm
(www.nano-device.eu). In the thermophoretic sampler (TP), a strong temperature gra-
dient exists between a heated plate and a temperature sink on which the TEM grid is
mounted. Azong-Wara et al. (2013) describe the development and testing of a personal
TP, which shows very good results for homogeneous loading of a substrate in the range
of a few nanometers to approximately 300 nm. This type of TP has been applied for the
development of a so called cyto-TP where the substrate is a well with a cell culture for
in vitro testing of real workplace nano aerosols (Broßell et al. 2013). A wider review on
aerosol characterization methods is given by Asbach in Chapter 2 of this topic.
Even though workplace exposure measurements are focused on personal expo-
sure, it becomes evident that this is not fully possible yet for nanoparticle exposure
measurements. Very few online and only a limited set of off-line sampling devices
for personal exposure measurements exist. All of them have only been developed
within the recent years so that only a very limited data set on exposure (related)
measurements exists.
13.3 REAL AND SIMULATED WORKPLACE OR RELEASE STUDIES
As mentioned earlier, a comprehensive review of nano exposure relevant publica-
tions was published by Kuhlbusch et al. (2011). Since then a number of new studies
have been published and this chapter will give an update of the review; however,
we have restructured the presentation of the summary of studies. The conceptual
model of inhalation exposure to nanoparticles (Schneider et al. 2011) has formed the
backbone of recent exposure modeling. Therefore the papers have been categorized
according to the so called source domains that include the vast majority of current
and near-future exposure situations for manufactured nano-objects. The rationale for
this categorization is that the source domains reflect different mechanisms of release
and consequently possible different forms of released aerosols. Moreover, they are
associated with the lifecycle stages of the nanomaterials, that is, production of the
nanomaterial, downstream use/incorporation in a matrix/a nano-enabled product, the
application of the product, the use phase, and activities related to the end-of-use.
1. Point source or fugitive emission during the production phase (synthesis)
prior to harvesting the bulk material; for example, emissions from the reac-
tor, leaks through seals and connections, and incidental releases (Figure 13.1).
2. Handling and transfer of bulk manufactured nanomaterial powders with
relatively low energy ; for example, collection, harvesting, bagging/bag
dumping, bag emptying, scooping, weighing, and dispersion/compounding
in composites (Figure 13.2).