Emissions from Consumer Products Containing Engineered Nanomaterials over Their Lifecycle - Safety of Nanomaterials along Their Lifecycle - page 344

released Ag was present as dissolved Ag + . It is known that the dissolution of Ag is
enhanced at low pH (Elzey and Grassian 2010; Liu and Hurt 2010).
15.3.5 s Prays
Sprays containing ENM, mainly nano-Ag, are on the market and are thus used by
many people (Quadros and Marr 2010). Sprays result in the direct aerosolization of
particles, and therefore complete release from the bottle to the environment occurs.
However, even sprays not containing any ENM form nanosized aerosols (Norgaard
et al. 2009), but the chemical identity of the nano-sized fraction was not studied by
these authors. However, for understanding the further fate and the effects of the aero-
solized particles their detailed characterization after release is necessary. Hagendorfer
et al. (2010) developed a method for quantification of the size and the composition of
ENM released from sprays. Controlled spray experiments were performed in a glove
box, and the time-dependent particle size distribution was studied using a scanning
mobility particle sizer (SMPS). The aerosol was also transferred to an electrostatic
TEM sampler. The particles deposited on the TEM grid were investigated using elec-
tron microscopy. The solid ENM were differentiated from the solvent droplets by
applying a thermo-desorbing unit. This setup was used to study various sprays. Pump
sprays resulted in no significant release of nanosized materials whereas gas-pressur-
ized cans resulted in significant release of nanosized materials. Figure 15.8 shows an
agglomerate of nano-NP from a propellant gas spray dispenser. The particles in the
original dispersions seem to be smaller in diameter than the released particles after
spraying, especially after a certain aging period of the aerosol.
Lorenz et al. (2011) investigated four commercially available nano-sprays and
identified ENM in two of them and nanosized aerosols in the three products that
used propellant gas. These nanosized aerosols consisted of a mixture of the spray
ingredients. Depending on the products and the mixture of the ingredients, different
400 nm
FIGURE 15.8 SEM image of an agglomerated Ag particle released from a spray. (With
kind permission from Springer+Business Media: J. Nanopart. Res . 12, Size-fractionated
characterization and quantification of nanoparticle release rates from a consumer spray prod-
uct containing engineered nanoparticles, 2010, 2481-2494, Hagendorfer, H. et al.)