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Xing M.,Centers for Disease Control and Prevention | Zhang Y.,Beijing Municipal Institute of Labour Protection | Zou H.,Centers for Disease Control and Prevention | Quan C.,Centers for Disease Control and Prevention | And 3 more authors.
Inhalation Toxicology | Year: 2015

The exposure characteristics of Fe2O3 nanoparticles (NPs) released in a factory were investigated, as exposure data on this type of NP is absent. The nature of the particles was identified in terms of their concentrations [i.e. number concentration (NC20-1000nm), mass concentration (MC100-1000nm), surface area concentration (SAC10-1000nm)], size distribution, morphology and elemental composition. The relationships between different exposure metrics were determined through analyses of exposure ranking (ER), concentration ratios (CR), correlation coefficients and shapes of the particle concentration curves. Work activities such as powder screening, material feeding and packaging generated higher levels of NPs as compared to those of background particles (p<0.01). The airborne Fe2O3 NPs exhibited a unimodal size distribution and a spindle-like morphology and consisted predominantly of the elements O and Fe. Periodic and activity-related characteristics were noticed in the temporal variations in NC20-1000nm and SAC10-1000nm. The modal size of the Fe2O3 NPs remained relatively constant (ranging from 10 to 15nm) during the working periods. The ER, CR values and the shapes of NC20-1000nm and SAC10-1000nm curves were similar; however, these were significantly different from those for MC100-1000nm. There was a high correlation between NC20-1000nm and SAC10-1000nm, and relatively lower correlations between the two and MC100-1000nm. These findings suggest that the work activities during the manufacturing processes generated high levels of primary Fe2O3 NPs. The particle concentrations exhibited periodicity and were activity dependent. The number and SACs were found to be much more relevant metrics for characterizing NPs than was the mass concentration. © 2015 Informa Healthcare USA, Inc.


Xing M.,Centers for Disease Control and Prevention | Zou H.,Centers for Disease Control and Prevention | Gao X.,Centers for Disease Control and Prevention | Chang B.,China National Institute of Occupational Health and Poison Control | And 2 more authors.
Environmental Sciences: Processes and Impacts | Year: 2015

Workplace exposure to airborne Al2O3 nanoparticles in a pilot factory was characterised by particle concentrations, size distribution, morphology and chemical composition, compared with background particles. Real-time variations in number concentration (NC20-1000 nm), respirable mass concentration (MC100-1000 nm), active surface area concentration (SAC10-1000 nm) and particle size were measured at production locations involved in separation and packaging activities. Measurements during stable production periods showed significant increases in the various concentrations of agglomerated Al2O3 nanoparticles (about 305 nm) at separation locations, compared to those of background particles (p < 0.01). The size distribution model for separation processes might switch to primary nanoparticles (21-26 nm) during periods of unstable production. Packaging activities also caused significant increases in different concentrations of Al2O3 nanoparticles (about 90 nm) compared to background particles (p < 0.01). These particles exhibited a bimodal size distribution and floccus or cloudy-like agglomerates of primary nanoparticles. NC20-1000 nm and active SAC10-1000 nm variations showed the same trend, and were temporally consistent with particle emission scenarios or worker activities, but differed from that for respirable MC100-1000 nm. There was strong correlation between active SAC10-1000 nm and NC20-1000 nm (r = 0.823), moderate correlation between active SAC10-1000 nm and respirable MC100-1000 nm (r = 0.666) and relatively weak correlation between NC20-1000 nm and respirable MC100-1000 nm (r = 0.361). These findings from the pilot factory suggest significant exposure to Al2O3 nanoparticles or their agglomerates, associated with separation and packaging processes. The number and active surface area concentrations may be distinct from mass concentration and might be more appropriate for characterizing exposure to airborne nanoparticles. This journal is © The Royal Society of Chemistry.

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