Lunar dust induces minimal pulmonary toxicity compared to Earth dust.

Humans are returning to the moon and understanding the toxicity of lunar dust is crucial for successful missions. Apollo mission reports suggest that lunar dust poses significant inhalation risks. Previous studies on lunar dust simulants have shown tissue and cellular damage in the lungs. This study focuses on two new simulants, LMS-1 and LHS-1, which closely replicate the lunar dust of the mare and highland regions of the moon. BEAS-2B and A549 cells were treated with unprocessed LMS-1 and LHS-1 (100µg/ml, 1000µg/ml and 5000µg/ml). The simulants were processed to isolate particles ≤2.5 µm, allowing a direct comparison to Earth dust (airborne particulate matter). BEAS-2B and A549 cells were treated with processed simulants and Earth dust (10µg/ml, 50µg/ml, and 100µg/ml) for 48 and 72 h. Inflammation was measured by measuring IL-6 and IL-8 using ELISA and cell viability was measured using a trypan blue exclusion test. A time- and dose-dependent increase in IL-8 and IL-6 production by LMS-1 and LHS-1 exposure was found only in BEAS-2B cells. A dose-dependent decrease in cell viability was found in both BEAS-2B and A549 cells with lunar dust simulant exposure. Particles ≤2.5 µms cause greater cell death than particles ≤1000µm. However, Earth dust induced greater cytokine release and was more toxic than lunar dust simulants. Lunar dust simulants did not increase SOD2 gene expression, indicating no increases in oxidative stress in either cell type. Therefore, our results suggest that lunar dust simulants are not highly toxic dusts, but rather a physical irritant. Future studies are needed to confirm the relative toxicity and irritant capacity of other lunar regions simulants.