Emissions from Consumer Products Containing Engineered Nanomaterials over Their Lifecycle - Safety of Nanomaterials along Their Lifecycle - page 340

smaller and larger than 0.45 μm. Electron microscopy revealed that the TiO 2 particles
released into the washing solution had primary particle sizes between 60 and 350 nm
and formed small aggregates with up to 20 particles. These results indicate that func-
tional textiles release only small amounts of TiO 2 particles and that the released par-
ticles are mostly not in the nanoparticulate range.
If we summarize all data obtained so far with textiles we can state that clearly
from many textiles significant release is observed but that the majority of the released
materials is not present as single nanoparticles but that a large variety of agglomer-
ates, transformation products, or precipitates are present in the washing solution.
Depending on the conditions also high concentrations of dissolved Ag can be found.
These results show that in most cases the nano-properties of the original material in
the textiles are lost and that the materials released are similar for nano-textiles and
conventional textiles containing the same material in non-nano form.
15.3.2 P aints
Paints containing nanoparticles represent an important use of ENM in the construc-
tion industry (Broekhuizen et al. 2011). Many paints for indoor and outdoor appli-
cations contain biocides and additives for protection against microbial, physical,
and chemical deterioration (Kaiser et al. 2013). Several studies have already inves-
tigated the release of materials from paints containing ENM. The first study—and
in fact the first report of an ENM in the environment—was performed by Kaegi
et al. (2008), who investigated the release of TiO 2 from outdoor paints. The authors
presented direct evidence of the release of nanomaterials from buildings into the
aquatic environment. TiO 2 particles were traced from painted facades through run-
off to surface waters. The concentration of Ti in runoffs from new facades was as
high as 600 µg/L. A centrifugation based sample preparation technique was used
which extracted TiO 2 particles between 20 and 300 nm and it was found that 85%-
90% of the total Ti in the samples occurred in this size range. Electron microscopy
revealed that the released Ti was present as TiO 2 particles. Figure 15.5 shows exam-
ples of particles observed in the runoff. Some of the particles are still embedded in
the organic binder (light gray zone around the particles). The same type of particles
were also found in a small stream into which the runoff was discharged. This find-
ing marks the first analytical verification of the presence of an ENM in the envi-
ronment. However, these nano-TiO 2 particles were released from a facade that did
NOT contain any nano-TiO 2 but only pigment TiO 2 . It has been shown that pigment
TiO 2 has a size distribution that extends into the nanoparticulate range (Weir et al.
2012). It is therefore not completely correct to call the observation of nano-TiO 2 in
the environment in the study of Kaegi et al. (2008) a verification of the presence of
ENM in the environment. It is rather a report about the presence of an incidental
nanoparticle, which is of course of utmost relevance when evaluating the potential
presence of real ENM. Further studies need to investigate how such engineered
nano-TiO 2 particles behave in paints and how their behavior is different from that
of the pigment TiO 2 .
The same authors also studied the behavior of a nano-Ag containing paint
(Kaegi et al. 2010). A painted panel was exposed to natural weather conditions