Biological radiation shielding in space: Safety of Cladosporium sphaerospermum

Vollständiger Abstract

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Space exploration exposes astronauts to chronic and acute cosmic radiation, representing one of the most significant health risks for long-duration missions, particularly beyond low Earth orbit. Current physical shielding technologies provide only partial protection and are limited by mass and engineering constraints. In this context, radiotrophic fungi capable of using ionizing radiation as an energy source through radiosynthesis have emerged as a novel approach to radiation attenuation. This narrative literature review critically evaluates the feasibility of employing Cladosporium sphaerospermum as a biological radiation shield in human spaceflight and examines the associated biosafety and health risks. Database searches were conducted in PubMed, Scientific Electronic Library Online, and Latin American and Caribbean Literature on Health Sciences between July 2025 and October 2025 using the terms “radiotrophic fungi,” “space medicine,” and “cosmic radiation,” focusing on publications from the past 15 years. Experimental studies, including those conducted aboard the International Space Station, indicate that C. sphaerospermum can reduce radiation exposure by approximately 2% and exhibit a relatively high linear attenuation coefficient when compared with lightweight materials such as water and carbon fiber. These findings highlight its theoretical potential as a self-replicating and adaptive radiation-attenuating system. However, species of the genus Cladosporium are recognized as opportunistic pathogens associated with phaeohyphomycosis, pulmonary infections, keratomycosis, and allergic diseases, posing substantial health risks in closed and microgravity environments where immune dysregulation may occur. Alternative non-biological shielding materials, including polyethylene, carbon fiber composites, and hydrogenated boron nitride nanotubes, offer more controllable and biosafe solutions and remain at more advanced stages of technological development. In conclusion, while C. sphaerospermum represents an innovative and conceptually compelling biotechnological strategy for radiation protection, its pathogenic potential currently limits its applicability in crewed space missions. Future research should prioritize bio-inspired or synthetic approaches that replicate the radioprotective properties of radiotrophic fungi while eliminating the risks associated with fungal colonization and infection.