Abstract
For assessing the inhalation toxicity of nanoparticles, we performed an inhalation study and an intratracheal instillation study of the same material, nickel oxide nanoparticle, at almost the same dose to rat lung and compared the results of the two methods.
In inhalation study, male Fisher 344 rats were exposed to NiO nanoparticles at 0, 1.65±0.20 and 0.32±0.07 mg/m3 for 4 weeks. In instillation study, 0, 0.2, 1 mg of NiO nanoparticle suspended in 0.4 ml distilled water were intratracheally instilled into male Fisher 344 rat's lung. In the recovery period after the inhalation and the instillation, each 10 rats of each group were dissected at from 3 days to 12 months and NiO amounts in 5 lungs each were determined by ICP-AES after acid digestion.
The NiO amounts at 3 days after the inhalation were 40±2.4 μg in low concentration exposure and 132±9.9 μg in high concentration exposure, respectively. And those at 3 days after the instillation were 136±6.5 μg in 0.2 mg and 738±50 μg in 1.0 mg, respectively. The amounts of NiO in lung at 3 days after the high inhalation exposure and those after 0.2 mg instillation were almost the same.
Biological half times of NiO until 6 months were 3.7 months in low and 4.5 months in high inhalation exposure and 4.9 months in 0.2 mg and 9.5 months in 1.0 mg, respectively.
Our results suggested that both inhalation study and instillation study show the similar biopersistence at almost the same lung dose. Further researches are continued.
This work is on the research program of “Development of innovative methodology for safety assessment of industrial nanomaterials" supported by Ministry of Economy, Trade and Industry (METI) of Japan.
- © 2014 ERS
