Cataractogenesis following high-LET radiation exposure

Publication date: Available online 20 August 2016 Source:Mutation Research/Reviews in Mutation Research Author(s): Nobuyuki Hamada, Tatsuhiko Sato Biological effectiveness of ionizing radiation differs with its linear energy transfer (LET) such that high-LET radiation is more effective for various biological endpoints than low-LET radiation. Human exposure to high-LET radiation occurs in cancer patients, nuclear workers, aviators, astronauts and other space travellers. From the radiation protection viewpoint, the ocular lens is among the most radiosensitive tissues in the body, and cataract (a clouding of the normally transparent lens) is classified as tissue reactions (formerly called nonstochastic or deterministic effects) with a threshold below which no effect would occur. To prevent radiation cataracts, the International Commission on Radiological Protection (ICRP) has recommended an equivalent dose limit for the lens according to the threshold for vision-impairing cataracts. ICRP recommended the threshold of >8Gy in 1984 and an occupational dose limit of 150 mSv/year in 1980. These remained unchanged until 2011, when ICRP recommended lowering the threshold to 0.5Gy and the dose limit to 20 mSv/year (averaged over 5 years with no single year exceeding 50 mSv). Although such reduction of the threshold was based on findings from low-LET radiation, the dose limit was recommended in Sv. Historically, the lens is the exceptional tissue for which ICRP had assigned a ...
Source: Mutation Research Reviews in Mutation Research - Category: Genetics & Stem Cells Source Type: research