Inter‐laboratory comparison of pulmonary lesions induced by intratracheal instillation of NiO nanoparticle in rats: Histopathological examination results

Objective In this study, in order to investigate the usefulness of intratracheal instillation in assessing the pulmonary toxicity of nanomaterials, intratracheal instillation of nickel oxide‐nanoparticles (NiO‐NP) was performed. Methods In this study, rats were administered test materials by intratracheal instillation at five different research institutions in order to assess the validity of using intratracheal instillation for hazard identification of nanomaterials. Eight‐week‐old male SD rats were administered NiO‐NP dispersed in deionized water by a single intratracheal instillation at doses of 0 (vehicle control), 0.2, 0.67, and 2 mg/kg BW. Three days after instillation, histopathological examination of the lungs was performed. Results NiO‐NP was distributed in the vicinity of hilus of the lung and in the alveoli around the bronchioles. Histopathological changes such as degeneration/necrosis of macrophages, inflammation, and proliferation of type II pneumocyte in the lung were observed, and their severity corresponded with increasing dose. The histopathological observations of pulmonary toxicity were almost similar at each institution. Conclusion The similarity of the histopathological changes observed by five independent groups indicates that intratracheal instillation can be a useful screening method to detect the pulmonary toxicity of nanomaterials.