Genome effects and mutational risk of radiation

Ionizing radiation is a part of the natural environment humans are exposed to on Earth. For cells, ionizing radiation is only one of many sources of stress that will be experienced during the course of a lifetime. The primary cellular target of ionizing radiation is DNA. Damage to DNA caused by ionizing radiation leads to mutations in somatic cells, often resulting in cancer; mutations of germ cells lead to hereditary mutations and, theoretically, genetic diseases. In addition, the presence of damaged nuclear DNA in cells can lead to genomic instability - a cellular state that can result in the accumulation of new mutations even several cell divisions after the DNA damage event. Types of mutations created in each case are slightly different and accumulate in nuclear, genomic DNA as well as mitochondrial genomes. The situation is further complicated by dissimilar effects of radiation of differing qualities, doses, and dose rates. Moreover, identical radiation treatments can have on different effects on specific cell types under specific environmental and physiological conditions, in organisms of different species, or different gender. Despite extensive efforts, there is much that is still not understood about radiation exposure, and the coming years will offer more opportunities to explore these areas.