Radiation burn

Damage to skin or biological tissue from radiation exposure

A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation. The most common type of radiation burn is a sunburn caused by UV radiation. High exposure to X rays during diagnostic medical imaging or radiotherapy can also result in radiation burns. As the ionizing radiation interacts with cells within the body—damaging them—the body responds to this damage, typically resulting in erythema—that is, redness around the damaged area. Radiation burns are often discussed in the same context as radiation induced cancer due to the ability of ionizing radiation to interact with and damage DNA, occasionally inducing a cell to become cancerous. Cavity magnetrons can be improperly used to create surface and internal burning. Depending on the photon energy, gamma radiation can cause deep gamma burns, with 60Co internal burns common. Beta burns tend to be shallow as beta particles are not able to penetrate deeply into a body; these burns can be similar to sunburn. Alpha particles can cause internal alpha burns if inhaled, with external damage (if any) being limited to minor erythema. Radiation burns can also occur with high power radio transmitters at any frequency where the body absorbs radio frequency energy and converts it to heat. The U. S. Federal Communications Commission (FCC) considers 50 watts to be the lowest power above which radio stations must evaluate emission safety. Frequencies considered especially dangerous occur where the human body can become resonant, at 35 MHz, 70 MHz, 80 100 MHz, 400 MHz, and 1 GHz. Exposure to microwaves of too high intensity can cause microwave burns.

Radiation dermatitis (also known as radiodermatitis) is a skin disease associated with prolonged exposure to ionizing radiation. There are three specific types of radiodermatitis: acute radiodermatitis, chronic radiodermatitis, and eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy. Radiation dermatitis, in the form of intense erythema and vesiculation of the skin, may be observed in radiation ports.

Acute radiodermatitis occurs when an "erythema dose" of ionizing radiation is given to the skin, after which visible erythema appears up to 24 hours after. Radiation dermatitis generally manifests within a few weeks after the start of radiotherapy. Erythema may occur at a dose of 2 Gy radiation or greater.

Chronic radiodermatitis occurs with chronic exposure to "sub erythema" doses of ionizing radiation over a prolonged period, producing varying degrees of damage to the skin and its underlying parts after a variable latent period of several months to several decades. Chronic radiodermatitis presents as atrophic indurated plaques, often whitish or yellowish, with telangiectasia, sometimes with hyperkeratosis. Radiation recall reactions occur months to years after radiation treatment, a reaction that follows recent administration of a chemotherapeutic agent and occurs with the prior radiation port, characterized by features of radiation dermatitis. Restated, radiation recall dermatitis is an inflammatory skin reaction that occurs in a previously irradiated body part following drug administration. There does not appear to be a minimum dose, nor an established radiotherapy dose relationship. Due to the keratin in the epidermal layer of the skin, external alpha burns are limited to only mild reddening of the outermost layer of skin.

Beta burns are frequently the result of exposure to radioactive fallout after nuclear explosions or nuclear accidents. Shortly after the explosion, the fission products have very high beta activity, with about two beta emissions per each gamma photon. After the Trinity test, the fallout caused localized burns on the backs of cattle in the area downwind. The fallout had the appearance of small flaky dust particles. The cattle showed temporary burns, bleeding, and loss of hair. Dogs were also affected; in addition to localized burns on their backs, they also had burned paws, likely from the particles lodged between their toes as hoofed animals did not show problems with feet. About 350–600 cattle were affected by superficial burns and localized temporary loss of dorsal hair; the army later bought 75 most affected cows as the discolored regrown hair lowered their market value. The cows were shipped to Los Alamos and Oak Ridge, where they were observed. They healed, now sporting large patches of white fur; some looked as if they had been scalded. The fallout produced by the Castle Bravo test was unexpectedly strong. A white snow like dust, nicknamed by the scientists "Bikini snow" and consisting of contaminated crushed calcined coral, fell for about 12 hours upon the Rongelap Atoll, depositing a layer of up to 2 cm. Residents developed beta burns, mostly on the backs of their necks and on their feet, The fishing ship Daigo Fukuryu Maru was affected by the fallout as well; the crew suffered skin doses between 1.7 and 6.0 Gy, with beta burns manifesting as severe skin lesions, erythema, erosions, sometimes necrosis, and skin atrophy. Twenty three U. S. radar servicemen of the 28 member weather station on Rongerik were affected, experiencing discrete 1–4 mm skin lesions which healed quickly, and ridging of fingernails several months later. Sixteen crew members of the aircraft carrier Bairoko received beta burns, and there was an increased cancer rate. The Upshot–Knothole Harry test at the Frenchman Flat site released a large amount of fallout. A significant number of sheep died after grazing on contaminated areas. The AEC however had a policy to compensate farmers only for animals showing external beta burns, so many claims were denied. Other tests on the Nevada Test Site also caused fallout and corresponding beta burns to sheep, horses and cattle. During the Operation Upshot–Knothole, sheep as far as 50 mile (80 km) from the test site developed beta burns to their backs and nostrils.

Beta burns were a serious medical issue for some victims of the Chernobyl disaster; from 115 patients treated in Moscow, 30% had burns covering 10–50% of body surface, 11% were affected on 50–100% of skin; the massive exposure was often caused by clothes drenched with radioactive water. Some firefighters developed beta burns of lungs and nasopharyngeal region after inhalation of massive amounts of radioactive smoke. Out of 28 deaths, 16 had skin injuries listed among the causes. The beta activity was extremely high, with beta/gamma ratio reaching 10–30 and beta energy high enough to damage basal layer of the skin, resulting in large area portals for infections, exacerbated by damage to bone marrow and weakened immune system. Some patients received skin dose of 400–500 Gy. The infections caused more than half of the acute deaths. Several died of fourth degree beta burns between 9–28 days after dose of 6–16 Gy. Seven died after dose of 4–6 Gy and third degree beta burns in 4–6 weeks. One died later from second degree beta burns and dose 1 4 Gy. Industrial radiography sources are a common source of beta burns in workers. Radiation therapy sources can cause beta burns during exposure of the patients. The sources can be also lost and mishandled, as in the Goiânia accident, during which several people had external beta burns and more serious gamma burns, and several died. Numerous accidents also occur during radiotherapy due to equipment failures, operator errors, or wrong dosage. Electron beam sources and particle accelerators can be also sources of beta burns. The burns may be fairly deep and require skin grafts, tissue resection or even amputation of fingers or limbs.

Radiation burns should be covered by a clean, dry dressing as soon as possible to prevent infection. Wet dressings are not recommended. The presence of combined injury (exposure to radiation plus trauma or radiation burn) increases the likelihood of generalized sepsis. This requires administration of systemic antimicrobial therapy.