Evaluation of skin cancer risk for lunar and Mars missions

Methods used to estimate the probability of excess incidence of skin cancer from space radiation exposure must take into consideration the variability of dose to different areas of the body and the individual factors that may contribute to increased risk, including skin pigment and synergistic effects from combined ionizing and UV exposure. We have estimated the skin cancer risk for future lunar and Mars missions using: (1) the multiplicative risk model for transferring the Japanese survivor data to the US population, (2) epidemiological data for the increased risk for skin locations exposed to combined UV and ionizing radiation, and (3) models of space radiation environments, transport, and anatomical shielding for 5260 skin loci. We have estimated that the probability for increased skin cancer risk from solar particle events varies more than 10-fold depending on the individual and area of skin exposed. We show that a skin cancer risk greater than 1% could occur for astronauts with light skin and hair color following exposure to medium or large class solar particle events during future lunar base operations, or from exposure to galactic cosmic rays during Mars missions.