Toxicological assessment of nano and micron-sized tungsten oxide after 28Â days repeated oral administration to Wistar rats

- Toxicological evaluation of WO3 NPs and MPs was performed after repeated oral exposure to rats.
- There was a clear size and dose-dependent genotoxicity as well as biodistribution.
- Majority of W from NP and MP-treated rats was excreted via urine and feces respectively.
- The effects of WO3 Particles were probably induced by W ions.
- The genotoxic effects of WO3 NPs could be mediated by oxidative stress and inflammation.

Tungsten oxide (WO3) nanoparticles (NPs) are being used in various applications. However, the health consequences of WO3 NPs exposure have not been explored extensively. Hence, the goal of this study was to evaluate the toxicity of WO3 NPs and their microparticles (MPs) after 28 days repeated oral administration in Wistar rats. The particles were characterised by transmission electron microscopy (TEM), dynamic light scattering (DLS), laser Doppler velocimetry (LDV), Brunner-Emmett-Teller (BET), X- ray diffraction (XRD), and inductively coupled plasma optical emission spectrometer (ICP-OES). Genotoxicity was determined using comet assay in blood and liver and micronucleus test in bone marrow. Biochemical parameters such as aspartate aminotransferase and alanine aminotransferase in serum and reduced glutathione content, catalase and lipid peroxidation in liver tissue were determined. Histopathological changes in tissues were documented. Biodistribution of tungsten (W) in rat's blood, urine, feces and tissues were analysed. The mean size of WO3 NPs and MPs by TEM was 52 ± 2.97 nm, and 5.73 ± 7.58 μm and morphology were spherical in both the particles. DLS of NPs was 195.6 nm. XRD and BET data of WO3 NPs and MPs showed a hexagonal and tetragonal crystal structure and surface area of 19.33 and 15.15 (m2/g), respectively. The results revealed a significant increase in DNA damage and micronuclei, a difference in biochemical levels and histopathological alterations after exposure to 1000 mg/kg dose of WO3 NPs. W biodistribution was detected in all the tissues in a dose and organ-dependent manner in both the particles. The highest amount of W was found in the liver and lowest in the brain of the treated rats. The tested NPs were found to have little toxicity hazard.