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When radiation deposits enough energy in organic tissue to cause ionization, this tends to break molecular bonds, and thus alter the molecular structure of the irradiated molecules. Less energetic radiation, such as visible light, only causes excitation, not ionization, which is usually dissipated as heat with relatively little chemical damage ...
Studies have been performed on the use of shortwave radiation for cancer therapy and promoting wound healing, with some success. However, at a sufficiently high energy level, shortwave energy can be harmful to human health, potentially causing damage to biological tissues, for example by overheating or inducing electrical currents. [28]
Ionizing radiation is known to cause cancer in humans. [4] We know this from the Life Span Study, which followed survivors of the atomic bombing in Japan during World War 2. [5] [4] Over 100,000 individuals were followed for 50 years. [5] 1 in 10 of the cancers that formed during this time was due to radiation. [6]
There is also evidence of a declining risk of cancer caused by radiation with increasing age, but the magnitude of this reduction above the age of 30 is uncertain. [6] It is unknown whether high-LET radiation could cause the same types of tumors as low-LET radiation, but differences should be expected. [9]
Radiolysis of intracellular water by ionizing radiation creates peroxides, which are relatively stable precursors to hydroxyl radicals. 60%–70% of cellular DNA damage is caused by hydroxyl radicals, [3] yet hydroxyl radicals are so reactive that they can only diffuse one or two molecular diameters before reacting with cellular components.
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 ...
Radiation embrittlement results in a reduction of the energy to fracture, due to a reduction in strain hardening (as hardening is already occurring during irradiation). This is motivated for very similar reasons to those that cause radiation hardening; development of defect clusters, dislocations, voids, and precipitates.
Evidence for carcinogenic effects of non-ionizing radiation is generally inconclusive, though there are some documented cases of radar technicians with prolonged high exposure experiencing significantly higher cancer incidence. [14] Higher-energy radiation, including ultraviolet radiation (present in sunlight) generally is carcinogenic, if ...