月粉じんの有害性評価手法の開発

Abstract

In order to explore whether lunar regolith induce airway hyperreactivity or bronchial asthma or not, we examined cellular influences of lunar regolith simulant whose component are similar to that of the lunar regolith. Particularly, we focused chemical component and particle size because the difference in the gravity between earth and moon, affect the different in the particle size of respirable dusts. The regolith simulant was fractionated to <10 μm, <25 μm and 10–25 μm by gravitational sedimentation in suspensions. The particle size with less than 10 μm means the respirable dust in earth, and particle size with less than 25 μm means respirable dusts in moon by calculating the one sixth of gravity of earth. Additionally, we also examined cellular influences of fine regolith simulant. Human lung carcinoma A549 cells were incubated at concentration of 0.1 and 1.0 mg/ml of these regolith simulants. After 24 h exposure, cytotoxicity, oxidative stress and immune response were examined. When the concentration was 1.0 mg/ml, cell membrane damage, mitochondrial dysfunction and induction of IL-8 were observed. Compared with crystalline silica which is positive control, cellular influences of the regolith simulant at concentration of 0.1 mg/ml were little. Secretion of IL-1β and TNF-α was observed at concentration of 1.0 mg/ml, however, induction of their gene expression did not observed at 24 h after exposure. Induction of cellular oxidative stress was small. Although the cell influence tended to be strong in the <10 μm particles, there was no remarkable difference. These results suggest that influence of chemical components and particles size on the cellular influence of lunar regolith simulant is small.