Exposure characteristics of ferric oxide nanoparticles released during activities for manufacturing ferric oxide nanomaterials

Abstract

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 (NC_{20–1000 nm}), mass concentration (MC_{100–1000 nm}), surface area concentration (SAC_{10–1000 nm})], 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 NC_{20–1000 nm} and SAC_{10–1000 nm}. The modal size of the Fe₂O₃ NPs remained relatively constant (ranging from 10 to 15 nm) during the working periods. The ER, CR values and the shapes of NC_{20–1000 nm} and SAC_{10–1000 nm} curves were similar; however, these were significantly different from those for MC_{100–1000 nm}. There was a high correlation between NC_{20–1000 nm} and SAC_{10–1000 nm}, and relatively lower correlations between the two and MC_{100–1000 nm}. 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.

• Exposure assessment
• ferric oxide
• nanoparticle
• occupational health

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

This work was supported by the Natural Science Foundation of China (81472961); the Co-constructed Projects by the National Health and Family Planning Commission of China and the Health Bureau of Zhejiang Province (WKJ2014-ZJ-0); the Science and Technology Fund of the Health Bureau of Zhejiang Province, China (2014KYB061); the Innovation Projects of the Beijing Academy of Science and Technology (PXM2014-178304-000001-00130138) and the Innovation Teamwork Projects of the Beijing Academy of Science and Technology (G201402N); the Health Standards Fund of the Ministry of Health, China (20130215); and the Science and Technology Fund of the Health Bureau of Zhejiang Province, China (2012KYB050).