DescriptionCertain kinds of nanomaterials have been shown to cause serious health effects. When various nanomaterials are introduced into consumer products, their use could lead to nanomaterial inhalation exposure with possible health effects. We explored the potential of this exposure for several consumer sprays and cosmetic powders including products marketed as nanotechnology-based and alternative non-nanotechnology-based products. Actual application of real world products was realistically simulated and the inhaled aerosol was measured directly. We described: 1) the nanoparticles and nano-agglomerates in products, to which exposure could occur during application by consumers; 2) the potential for inhalation exposure to nanomaterial-containing particulate matter, generated during product application; and 3) the quantitative nanomaterial inhalation exposure as both inhaled dose and dose deposited in different regions of the human respiratory tract (for the cosmetic powders only). Particles in the products were investigated using transmission electron microscopy (TEM), photon correlation spectroscopy (PCS) and laser diffraction spectroscopy (LDS). We then realistically simulated the use of the products by spraying them in the vicinity of a female mannequin head or applying directly onto its face in the case of cosmetic powders. A Scanning Mobility Particle Sizer (SMPS) and an Aerosol Particle Sizer (APS) were used to measure the “inhaled” aerosol particle size distributions by drawing aerosol through the mannequin’s nostrils. The measurement data for powders were also used in an inhalation exposure model. Nanoparticles were found in both the nanotechnology-based and regular products. We could not, however, determine their engineered status. It was concluded that the highest inhalation exposure to nanomaterials in the investigated consumer products would occur due to inhalation and deposition of nanoparticle agglomerates larger than 100 nm – not individual nanoparticles or nanosized agglomerates. For the cosmetic powders, inhaled particle deposition in the head airways constituted the dominant portion (85-93%) of the total deposited dose overwhelming the deposition in the tracheobronchial and the alveolar regions. Hence, the future toxicology studies of nanotechnology-based consumer products should take into account exposures not only to single nanoparticles, but also to much larger nanoparticle agglomerates and investigate the potential biological effects in all regions of the respiratory tract.