Toxicity Provoked by Exposure of Human Lung Cells to Lunar Regolith Simulants

Abstract:

It became clear during the Apollo missions that lunar dust is a potential hazard to astronauts when brought back into living spaces after adhering strongly to their space suits. The term “lunar hay fever” was coined by geologist-astronaut Harrison Schmidt to describe the respiratory and eye irritations caused by the dust. With the planned human return to Moon in 2024, this problem merits further attention. We showed previously that pulverizing lunar regolith simulant materials (to mimic the effects of micrometeorites) strongly enhanced their toxicity to cells. Another form of “space-weathering” is solar wind, which in current studies we mimic by treating the freshly-pulverized materials with H₂ gas at high temperature. Use of H₂-roasted Lunar Mare Simulant-1 and Lunar Highlands Simulant-1 enhanced their ability to damage DNA in human alveolar lung cells and produced dysfunction of the cellular “powerhouse” organelles, mitochondria. Based on this and a previous study, it appears that these effects arise both from chemical aspects of the simulants (e.g., free radical formation) and from microscopic interaction with the cells that may promote inflammation. We are currently examining the effect of the iron:magnesium ratio of solid solutions in causing cellular damage. Gene-silencing techniques will help verify the specific cellular targets of simulant exposure.

Our work provides key information on the effects of lunar regolith constituents at the cellular level. This, in turn, informs the understanding of tissue-level toxicity and health risks to astronauts and may provide biomarkers to assess exposure level. Such understanding could support the development of physiological preventive measures applicable to respiratory diseases.

Supported by NASA grant NNA114AB04A (P.I.: T. Glotch).