Quantitative assessment of inhalation exposure and deposited dose of aerosol from nanotechnology-based consumer sprays

Abstract

This study provides a quantitative assessment of inhalation exposure and deposited aerosol dose in the 14 nm to 20 μm particle size range based on the aerosol measurements conducted during realistic usage simulation of five nanotechnology-based and five regular spray products matching the nano-products by purpose of application. The products were also examined using transmission electron microscopy. In seven out of ten sprays, the highest inhalation exposure was observed for the coarse (2.5–10 μm) particles while being minimal or below the detection limit for the remaining three sprays. Nanosized aerosol particles (14–100 nm) were released, which resulted in low but measurable inhalation exposures from all of the investigated consumer sprays. Eight out of ten products produced high total deposited aerosol doses on the order of 101–103 ng kg−1 bw per application, ~85–88% of which were in the head airways, only <10% in the alveolar region and <8% in the tracheobronchial region. One nano and one regular spray produced substantially lower total deposited doses (by 2–4 orders of magnitude less), only ~52–64% of which were in the head while ~29–40% in the alveolar region. The electron microscopy data showed nanosized objects in some products not labeled as nanotechnology-based and conversely did not find nano-objects in some nano-sprays. We found no correlation between nano-object presence and abundance as per the electron microscopy data and the determined inhalation exposures and deposited doses. The findings of this study and the reported quantitative exposure data will be valuable for the manufacturers of nanotechnology-based consumer sprays to minimize inhalation exposure from their products, as well as for the regulators focusing on protecting the public health.

Development of linear and threshold no significant risk levels for inhalation exposure to titanium dioxide using systematic review and mode of action considerations

“…Using the surface area lung burden dose metric, some regulators have derived toxicity criteria for ultrafine TiO 2 that are~10-fold lower than fine TiO 2 (Dankovic et al, 2007;NIOSH, 2011); however, it remains unclear whether surface area fully explains the potency differences between fine and ultrafine TiO 2 (Section 3.3). Moreover, environmental exposure to pure ultrafine particles has been questioned (Nazarenko et al, 2012a(Nazarenko et al, , 2014. Our proposed RfC for TiO 2 includes a 3-fold UF D to account for uncertainties with respect to exposure to potentially more potent forms of TiO 2 (e.g.…”

“…For example, one study with three different ultrafine TiO 2 samples reported that the median diameters were >100 nm in water and >2.5 mm in phosphate buffered saline (Warheit et al, 2007). Recent studies with marketed cosmetic and spray products containing nanomaterials (some including TiO 2 ), found that nanoparticles within the products tend to agglomerate, thereby lessening exposure to ultrafine material (Nazarenko et al, 2014(Nazarenko et al, , 2012a(Nazarenko et al, , 2012b. Moreover, these studies also predicted that the vast majority of product deposition occurred in the head airways as opposed to alveolar regions of the lung (Nazarenko et al, 2012a(Nazarenko et al, , 2014.…”

“…Moreover, many toxicity studies employ relatively pure nanoparticles, whereas consumers are typically exposed to products (i.e. mixtures) that may contain some fraction of nanomaterial along with many other ingredients (Nazarenko et al, 2014(Nazarenko et al, , 2012a(Nazarenko et al, , 2012b. It is known, however, that nanoparticles tend to agglomerate and aggregate to decrease the surface to volume ratio and decrease the free energy of the system (Simakov et al, 2007).…”

“…Recent studies with marketed cosmetic and spray products containing nanomaterials (some including TiO 2 ), found that nanoparticles within the products tend to agglomerate, thereby lessening exposure to ultrafine material (Nazarenko et al, 2014(Nazarenko et al, , 2012a(Nazarenko et al, , 2012b. Moreover, these studies also predicted that the vast majority of product deposition occurred in the head airways as opposed to alveolar regions of the lung (Nazarenko et al, 2012a(Nazarenko et al, , 2014. It is also notable that some products marketed as containing nanoparticles were not found to have any nanoscale particles, whereas some products not marketed as containing nanomaterials clearly contained nanoscale materials.…”

Physicochemical characteristics of colloidal nanomaterial suspensions and aerosolized particulates from nano‐enabled consumer spray products

“…Therefore, comparison of both suspension and aerosol analysis has been conducted in several studies 14,[16][17][18][19]32 to complement the limitations because it can suggest how the size and particle concentrations change during the spray process by the spray nozzle type. 15 There is no single analytical method or instrument able to evaluate the properties of nanoparticles in a variety of media in the F I G U R E 6 Temporal variation in count median diameter before and after spraying environment, so it could be obtained using a combination of some methods to complement the disadvantages of each method (physical properties: microscopic analysis, light scattering, field-flow fractionation, X-ray diffraction and etc; chemical composition: ICP-MS, EDX with EM, and others).…”