Geochemical Hazard Assessment of Martian Regolith for Future Human Exploration

Abstract

As human missions to Mars move from concept to planning to reality, a systematic quantitative health risk assessment of martian regolith exposure has become critically important. This study presents a comprehensive multi-element, multi-pathway health hazard analysis of martian regolith for a 70 kg adult astronaut on an 18-month surface mission, using bulk silicate Mars geochemical data and Earth Upper Continental Crust reference values as baseline comparators. We computed Average Daily Dose, Hazard Quotient, Hazard Index, Enrichment Factor, Ecological Risk Factor, and Incremental Lifetime Cancer Risk across all three exposure pathways (oral ingestion, inhalation, and dermal contact) for toxic and heavy metals, under four filtration scenarios (0%, 25%, 50%, 95%). Results demonstrate that Cr and Co represent the most critical non-carcinogenic hazards, exceeding the regulatory threshold (HI > 1) even at 50% filtration, while Cr also poses the most significant carcinogenic risk, near the $10^{-4}$ regulatory threshold level. At least 92% regolith filtration efficiency is required to reduce Cr to acceptable non-cancer hazard levels. Nickel exceeds the acceptable cancer risk threshold of $10^{-6}$ at all filtration levels below 95%. No element other than Cr and Co exceeds HI = 1 in the unfiltered scenario, although Fe, Ni and Mn approach concerning levels. These results establish that a minimum 95% High-Efficiency Particulate Air (HEPA)-grade filtration efficiency combined with active chemical sorption is required for acceptable Cr and Co short term exposure and Cr, Ni long term exposure management. This study provides a pathway-specific quantitative risk framework applicable to habitat air quality standards and EVA suit specifications for Mars surface operations