Molecular and clinical effects of radon exposure and risk assessment in blood, Review

Radon (²²²Rn) is a radioactive noble gas decay product of uranium found in soil and rock. It is considered a strong environmental carcinogen and has a significant role in the disease of lung cancer across the globe. Although its locoregional damage to respiratory epithelium is well-established, there is increasing evidence that the effects of radon exposure are systemic with molecular and cellular consequences that are able to be assayed in peripheral blood. Alpha particles, representing radon progeny, produce high-LET radiation that leads to complex DNA lesions including double strand breaks, chromosomal aberrations and genomic instability. Furthermore, radon exposure has been reported to be related to oxidative stress and inflammation, epigenetic changes, and immune disorders. Blood markers such as γ-H2AX foci, micronucleus frequency, indicators of DNA damage (comet) and translocations have shown promise in early biomonitoring. The present review has summarized data from relevant epidemiological, cytogenetic, molecular and clinical studies to establish the biological effects induced by radon-exposure in peripheral blood and considered implications for environmental health risk assessment.