Radon Exposure: A Comprehensive Review of the Health Risks and Therapeutic Potentials.

Radon, a naturally occurring radioactive gas, is classified as a Group 1 carcinogen by the World Health Organization (WHO) and remains a significant environmental health hazard. Radon exposure is the second leading cause of lung cancer worldwide, and lung cancer remains the only health outcome firmly established to be caused by radon exposure. Possible associations with chronic obstructive pulmonary disease, hematological disorders, skin diseases, and other conditions remain under investigation. This review explores the broad spectrum of health risks associated with radon exposure, including its biological effects at histopathological, cellular, and molecular levels, with a focus on unique radiation effects such as the bystander effect and inverse dose-rate effect. Despite its harmful effects, radon has also been investigated for potential therapeutic effects under controlled exposure conditions, although the strength of clinical evidence varies across indications. Known as radon therapy, it has been investigated primarily for rheumatic and musculoskeletal disorders, while evidence for neurological disorders and cancer-related applications remains largely experimental or limited. The biological mechanisms of radon therapy, including its regulation of oxidative stress, immune modulation, and redox balance, are discussed. The effects of radon on human health, whether harmful or therapeutic, are highly dependent on factors such as dose, exposure duration, and individual susceptibility. This review concludes by highlighting key areas for future research to refine our understanding of both the risks and therapeutic applications of radon.