Assessment of Occupational Exposure to Indium Dust for Indium-Tin-Oxide Manufacturing Workers

Release of indium from In2O3 nanoparticles in model solutions and synthetic seawater

Indium oxide (In2O3) nanoparticles (NPs) are used in electronic devices, from which indium (as its nanoparticulate form or as other generated chemical species) can be released to natural waters. To assess for the impacts of such releases (e.g. toxic effects), information on the kinetics and thermodynamics of the In2O3 dissolution processes is key. In this work, the evolution with time of the dissolution process was followed with the technique AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) by measuring the free indium concentration ([In3+]). AGNES can determine the free ion concentration in the presence of nanoparticles without a prior separation step, as shown in the case of ZnO nanoparticles, a procedure that is more accurate than the typical sequence of centrifugation+filtration+elemental analysis. Excess of indium oxide NPs were dispersed in 0.1 mol L-1 KNO3 at various pH values ranging from 2 to 8. Additional dispersions with bulk In2O3 at pH 3 or NPs in synthetic seawater at pH 8 were also prepared. The temperature was carefully fixed at 25 °C. The dispersions were continuously stirred and samples were taken from time to time to measure free indium concentration with AGNES. 180-day contact of In2O3 to solutions at pH 2 and 3 was not enough to reach equilibrium. The dissolution of the NPs at pH 3 was faster than that of the bulk (i.e. non nanoparticulate) material. Equilibrium of the NPs with the solution was reached at pH 4 and 5 in KNO3 and at pH 8 in seawater, in shorter times for higher pH values, with free indium concentrations decreasing by a factor of 1000 for each increase in one pH unit. The solubility products of In(OH)3 and In2O3 were compared. Equilibration of NPs with synthetic seawater took <18 days, with an average free [In3+] (up to 196 days) of 1.03 amol L-1.

Nose-to-brain translocation and nervous system injury in response to indium tin oxide nanoparticles of long-term low-dose exposures

Indium tin oxide (ITO) is a semiconductor nanomaterial with broad application in liquid crystal displays, solar cells, and electrochemical immune sensors. It is worth noting that, with the gradual increase in worker exposure opportunities, the exposure risk in occupational production cannot be ignored. At present, the toxicity of ITO mainly focuses on respiratory toxicity. ITO inhaled through the upper respiratory tract can cause pathological changes such as interstitial pneumonia and pulmonary fibrosis. Still, extrapulmonary toxicity after nanoscale ITO nanoparticle (ITO NPs) exposure, such as long-term effects on the central nervous system, should also be of concern. Therefore, we set up exposure dose experiments (0 mg·kg-1, 3.6 mg·kg-1, and 36 mg·kg-1) based on occupational exposure limits to treat C57BL/6 mice via nasal drops for 15 weeks. Moreover, we conducted a preliminary assessment of the neurotoxicity of ITO NPs (20-30 nm) in vivo. The results indicated that ITO NPs can cause diffuse inflammatory infiltrates in brain tissue, increased glial cell responsiveness, abnormal neuronal cell lineage transition, neuronal migration disorders, and neuronal apoptosis related to the oxidative stress induced by ITO NPs exposure. Hence, our findings provide useful information for the fuller risk assessment of ITO NPs after occupational exposure.

Health and Environmental Effect of Advanced Materials and Fine Particles

With the recent development in material sciences, advanced materials have become terms widely used for new materials [...]