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Radiation hormesis is the conjecture that a low level of ionizing radiation (i.e., near the level of Earth's natural background radiation) helps "immunize" cells against DNA damage from other causes (such as free radicals or larger doses of ionizing radiation), and decreases the risk of cancer. The theory proposes that such low levels activate ...
Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic , and epigenetic levels and abnormal cell division .
A carcinogen (/ k ɑːr ˈ s ɪ n ə dʒ ən /) is any agent that promotes the development of cancer. [1] Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. [2]
Residential exposure to radon gas, for example, has similar cancer risks as passive smoking. Radiation is a more potent source of cancer when combined with other cancer-causing agents, such as radon plus tobacco smoke. Radiation can cause cancer in most parts of the body, in all animals and at any age.
Increased Risk of Solid Cancer with Dose for A-bomb survivors, from BEIR report.Notably, this exposure pathway occurred from essentially a massive spike or pulse of radiation, a result of the brief instant that the bomb exploded, which while somewhat similar to the environment of a CT scan, is wholly unlike the low dose rate of living in a contaminated area such as Chernobyl, where the dose ...
Ionizing radiation may be used to treat other cancers, but this may, in some cases, induce a second form of cancer. [74] Radiation can cause cancer in most parts of the body, in all animals, and at any age, although radiation-induced solid tumors usually take 10–15 years, and can take up to 40 years, to become clinically manifest, and ...
Kerala's monazite sand (containing a third of the world's economically recoverable reserves of radioactive thorium) emits about 8 microsieverts per hour of gamma radiation, 80 times the dose rate equivalent in London, but a decade-long study of 69,985 residents published in Health Physics in 2009 "showed no excess cancer risk from exposure to ...
However as microgravity has been shown to modulate cancer progression, more research is needed into the combined effects of microgravity and radiation on carcinogenesis. [8] The effects of changes in oxygen levels or in immune dysfunction on cancer risks are largely unknown and are of great concern during space flight.