Review Articles Low-dose Radiation Exposure and Carcinogenesis

Absorption of energy from ionizing radiation by the genetic material in the cell leads to damage to DNA, which in turn leads to cell death, chromosome aberrations and gene muta-tions. While early or deterministic effects result from organ and tissue damage caused by cell killing, latter two are considered to be involved in the initial events that lead to the develop-ment of cancer. Epidemiological studies have demonstrated the dose–response relationships for cancer induction and quantitative evaluations of cancer risk following exposure to moder-ate to high doses of low-linear energy transfer radiation. A linear, no-threshold model has been applied to assessment of the risks resulting from exposure to moderate and high doses of ionizing radiation; however, a statistically significant increase has hardly been described for radiation doses below 100 mSv. This review summarizes our current knowledge of the physical and biological features of low-dose radiation and discusses the possibilities of induction of cancer by low-dose radiation. Key words: ionizing radiation – low-dose – epidemiology – thyroid cancer – A-bomb survivors – Chernobyl acciden