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88-481: Sunburn is a form of radiation burn that affects living tissue , such as skin , that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun . Common symptoms in humans and other animals include red or reddish skin that is hot to the touch or painful , general fatigue , and mild dizziness . Other symptoms include blistering , peeling skin , swelling, itching, and nausea. Excessive UV radiation

176-407: 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

264-405: 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. Melanocyte Melanocytes are melanin -producing neural crest -derived cells located in

352-449: A continuous spectrum with a cutoff at maximum energy. The rest of the energy of each decay is carried off by an antineutrino which does not significantly interact and therefore does not contribute to the dose. Most energies of beta emissions are at about a third of the maximum energy. Beta emissions have much lower energies than what is achievable from particle accelerators, no more than few megaelectronvolts. The energy-depth-dose profile

440-493: 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. In the past this type of radiation reaction occurred most frequently in radiologists and radiographers who were constantly exposed to ionizing radiation, especially before

528-415: A given pathogen. In addition, cytokine production by melanocytes can be triggered by cytokines secreted by other nearby immune cells. Melanocytes are ideally positioned in the epidermis to be sentinels against harmful pathogens. They reside in the stratum basale , the lowest layer of the epidermis , but they use their dendrites to interact with cells in other layers, and to capture pathogens that enter

616-426: A hair is lost and the hair follicle regenerates, the stem cells are activated. These stem cells develop into both keratinocyte precursors and melanoblasts - and these melanoblasts supply both hair and skin (moving into the basal layer of the epidermis ). There is additionally evidence that melanocyte stem cells are present in cutaneous nerves, with nerve signals causing these cells to differentiate into melanocytes for

704-426: A photoprotectant. By preventing UV photons from disrupting chemical bonds, melanin inhibits both the direct alteration of DNA, as well as the generation of free radicals , to prevent them from indirectly damaging DNA. However, human melanocytes contain over 2,000 genomic sites that are highly sensitive to UV , and such sites can be up to 170-fold more sensitive to UV induction of cyclobutane pyrimidine dimers than

792-529: 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. "Alpha burns" are caused by alpha particles , which can cause extensive tissue damage if inhaled. Due to

880-575: A role in the immune system . Through a process called melanogenesis, melanocytes produce melanin , which is a pigment found in the skin , eyes , hair , nasal cavity , and inner ear . This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from oxidation of already-existing melanin. There are both basal and activated levels of melanogenesis; in general, lighter-skinned people have low basal levels of melanogenesis. Exposure to UV-B radiation causes increased melanogenesis. The purpose of melanogenesis

968-506: A skin reaction. Some reactions are immediate, while others may be later (e.g., months after treatment). 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. Acute radiodermatitis, while presenting as red patches, may sometimes also present with desquamation or blistering. Erythema may occur at

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1056-414: Is spider veined and with underlying fibrosis . The burns may manifest at different times at different body areas. The Chernobyl liquidators ' burns first appeared on wrists, face, neck and feet, followed by chest and back, then by knees, hips and buttocks. Industrial radiography sources are a common source of beta burns in workers. Radiation therapy sources can cause beta burns during exposure of

1144-436: 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

1232-418: Is a curve starting with a surface dose, ascending to the maximum dose in a certain depth d m (usually normalized as 100% dose), then descends slowly through depths of 90% dose (d 90 ) and 80% dose (d 80 ), then falls off linearly and relatively sharply though depth of 50% dose (d 50 ). The extrapolation of this linear part of the curve to zero defines the maximum electron range, R p . In practice, there

1320-516: Is a long tail of weaker but deep dose, called "bremsstrahlung tail", attributable to bremsstrahlung . The penetration depth depends also on beam shape, narrower beam tend to have less penetration. In water, broad electron beams, as is the case in homogeneous surface contamination of skin, have d 80 about E/3 cm and R p about E/2 cm, where E is the beta particle energy in MeV. The penetration depth of lower-energy beta in water (and soft tissues)

1408-466: Is a sign of second-degree sunburn. Minor sunburns typically cause nothing more than slight redness and tenderness to the affected areas. In more serious cases, blistering can occur. Extreme sunburns can be painful to the point of debilitation and may require hospital care. Sunburn can occur in less than 15 minutes in response to sun exposure and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless,

1496-591: Is a type of radiation burn , it can initially hide a severe exposure to radioactivity . Excess radiation exposure may result in acute radiation syndrome or other radiation-induced illnesses, especially in sunny conditions. For instance, the difference between the erythema caused by sunburn and other radiation burns is not immediately obvious. Symptoms common to heat illness and the prodromic stage of acute radiation syndrome like nausea, vomiting, fever, weakness/fatigue, dizziness or seizure can add to further diagnostic confusion. The most effective way to prevent sunburn

1584-479: Is about 2 mm/MeV. For a 2.3 MeV beta the maximum depth in water is 11 mm, for 1.1 MeV it is 4.6 mm. The depth where maximum of the energy is deposited is significantly lower. The energy and penetration depth of several isotopes is as follows: For a wide beam, the depth-energy relation for dose ranges is as follows, for energies in megaelectronvolts and depths in millimeters. The dependence of surface dose and penetration depth on beam energy

1672-745: Is also evidence that common foods may have some protective ability against sunburn if taken for a period before exposure. Babies and children are particularly susceptible to UV damage which increases their risk of both melanoma and non-melanoma skin cancers later in life. Children should not sunburn at any age, and protective measures can reduce their future risk of skin cancer. The WHO recommends that artificial UV exposure, including tanning beds, should be avoided as no safe dose has been established. Special protective clothing (for example, welding helmets/shields) should be worn when exposed to any artificial source of occupational UV. Such sources can produce UVC, an extremely carcinogenic wavelength of UV, which ordinarily

1760-475: Is an indication of injury severe enough to cause chronic radiation dermatitis. Edema of dermal papillae , if present within 48 hours since the exposition, is followed by transepidermal necrosis . After higher doses, the malpighian layer cells die within 24 hours; lower doses may take 10–14 days to show dead cells. Inhalation of beta radioactive isotopes may cause beta burns of lungs and nasopharyngeal region, ingestion may lead to burns of gastrointestinal tract;

1848-438: Is clearly seen following the polymerization to melanin, the color of the pigment ranges from red to dark brown. Numerous stimuli are able to alter melanogenesis, or the production of melanin by cultured melanocytes, although the method by which it works is not fully understood. Increased melanin production is seen in conditions where adrenocorticotropic hormone (ACTH) is elevated, such as Addison's and Cushing's disease . This

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1936-411: Is clearly visible. Radiation burns are caused by exposure to high levels of radiation. Levels high enough to cause burn are generally lethal if received as a whole-body dose, whereas they may be treatable if received as a shallow or local dose. Fluoroscopy may cause burns if performed repeatedly or for too long. Similarly, X-ray computed tomography and traditional projectional radiography have

2024-880: Is found only on "professional" antigen presenting cells such as dendritic cells, macrophages , B cells , and melanocytes. Importantly, melanocytes stimulated by cytokines express surface proteins such as CD40 and ICAM1 in addition to MHC class II, allowing for co-stimulation of T cells. In addition to presenting antigen, one of the roles of melanocytes in the immune response is cytokine production. Melanocytes express many proinflammatory cytokines including IL-1 , IL-3 , IL-6 , IL-8 , TNF-α , and TGF-β . Like other immune cells, melanocytes secrete these cytokines in response to activation of Pattern Recognition Receptors (PRRs) such as Toll Like Receptor 4 (TLR4) which recognize MAMPs . MAMPs, also known as PAMPs, are microbial associated molecular patterns, small molecular elements such as proteins, carbohydrates, and lipids present on or in

2112-450: Is given prophylactically to neurosurgical patients who are receiving whole-brain therapy and systemic steroids. Radiation acne is a cutaneous condition characterized by comedo-like papules occurring at sites of previous exposure to therapeutic ionizing radiation, skin lesions that begin to appear as the acute phase of radiation dermatitis begins to resolve. Radiation recall reactions occur months to years after radiation treatment,

2200-400: Is in the lower UVC band that is rarely encountered except from artificial sources like welding arcs. Longer wavelengths of UV radiation cause most sunburn because those wavelengths are more prevalent in ground-level sunlight. In recent decades, the incidence and severity of sunburn have increased worldwide, partly because of chemical damage to the atmosphere's ozone layer. Between the 1970s and

2288-502: Is initial redness, followed by varying degrees of pain, the severity of which correlates with the duration and intensity of sun exposure. Other symptoms can include blistering , swelling ( edema ), itching ( pruritus ), peeling skin , rash , nausea , fever , chills , and fainting ( syncope ). Also, heat is produced from capillaries close to the skin surface, therefore the affected area feels warm to touch. Sunburns may be classified as superficial or partial-thickness burns . Blistering

2376-488: Is mainly a consequence of alpha-MSH being secreted along with the hormone associated with reproductive tendencies in primates. Alpha-MSH is a cleavage product of ACTH that has an equal affinity for the MC1 receptor on melanocytes as ACTH. Melanosomes are vesicles that package the chemical inside a plasma membrane . The melanosomes are organized as a cap protecting the nucleus of the keratinocyte . When ultraviolet rays penetrate

2464-399: Is not necessarily at 12 pm, but often one to two hours later. Seeking shade using umbrellas and canopies can reduce UV exposure, but does not block all UV rays. The WHO recommends following the shadow rule: "Watch your shadow – Short shadow, seek shade!" Commercial preparations that block UV light are known as sunscreens or sunblocks. They have a sun protection factor (SPF) rating based on

2552-668: Is not present in normal sunlight, having been filtered out by the atmosphere. The primary measure of treatment is avoiding further exposure to the sun . The best treatment for most sunburns is time; most sunburns heal completely within a few weeks. The American Academy of Dermatology recommends the following for the treatment of sunburn: Non-steroidal anti-inflammatory drugs (NSAIDs; such as ibuprofen or naproxen ), and aspirin may decrease redness and pain. Local anesthetics such as benzocaine , however, are contraindicated. Schwellnus et al. state that topical steroids (such as hydrocortisone cream ) do not help with sunburns, although

2640-449: Is provided by clothing, especially shoes. The dose is further reduced by limited retention of radioactive particles on skin; a 1 millimeter particle is typically released in 2 hours, while a 50 micrometer particle usually does not adhere for more than 7 hours. Beta emissions are also severely attenuated by air; their range generally does not exceed 6 feet (1.8 m) and intensity rapidly diminishes with distance. The eye lens seems to be

2728-638: Is the leading cause of (primarily) non-malignant skin tumors , which in extreme cases can be life-threatening. Sunburn is an inflammatory response in the tissue triggered by direct DNA damage by UV radiation. When the cells ' DNA is overly damaged by UV radiation, type I cell-death is triggered and the tissue is replaced. Sun protective measures like sunscreen and sun protective clothing are widely accepted to prevent sunburn and some types of skin cancer . Special populations, including children, are especially susceptible to sunburn and protective measures should be used to prevent damage. Typically, there

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2816-446: Is to protect the hypodermis , the layer under the skin, from damage by UV radiation. The color of the melanin is black, allowing it to absorb a majority of the UV light and block it from passing through the epidermis. Since the action spectrum of sunburn and melanogenesis are virtually identical, they are assumed to be induced by the same mechanism. The agreement of the action spectrum with

2904-549: Is to reduce the amount of UV radiation reaching the skin. The World Health Organization, American Academy of Dermatology, and Skin Cancer Foundation recommend the following measures to prevent excessive UV exposure and skin cancer: The strength of sunlight is published in many locations as a UV Index . Sunlight is generally strongest when the Sun is close to the highest point in the sky. Due to time zones and daylight saving time, this

2992-457: The American Academy of Dermatology says they can be used on especially sore areas. While lidocaine cream (a local anesthetic) is often used as a sunburn treatment, there is little evidence for the effectiveness of such use. A home treatment that may help the discomfort is using cool and wet cloths on the sunburned areas. Applying soothing lotions that contain aloe vera to sunburned areas

3080-526: 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, and were resettled after three days. After 24–48 hours their skin

3168-512: The MSH and ACTH peptides that are produced from the precursor proopiomelanocortin. Vitiligo is a skin disease where people lack melanin in certain areas in the skin. People with oculocutaneous albinism typically have a very low level of melanin production. Albinism is often but not always related to the TYR gene coding the tyrosinase enzyme. Tyrosinase is required for melanocytes to produce melanin from

3256-711: The Operation Upshot–Knothole , sheep as far as 50 miles (80 km) from the test site developed beta burns to their backs and nostrils. During underground nuclear testing in Nevada, several workers developed burns and skin ulcers, in part attributed to exposure to tritium . 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;

3344-683: The Skin Cancer Foundation have recommended avoiding artificial UV sources such as tanning beds. Suntans are not recommended as a form of sun protection. The differential diagnosis of sunburn includes other skin pathology induced by UV radiation, including photoallergic reactions, phototoxic reactions to topical or systemic medications, and other dermatologic disorders that are aggravated by exposure to sunlight. Considerations for diagnosis include duration and intensity of UV exposure, topical or systemic medication use, history of dermatologic disease, and nutritional status. Additionally, since sunburn

3432-507: The amino acid tyrosine . Albinism may be caused by a number of other genes as well, like OCA2 , SLC45A2 , TYRP1 , and HPS1 to name some. In all, already 17 types of oculocutaneous albinism have been recognized. Each gene is related to different protein having a role in pigment production. People with Chédiak–Higashi syndrome have a buildup of melanin granules due to abnormal function of microtubules . In addition to their role as UV radical scavengers, melanocytes are also part of

3520-524: The bone marrow . Melanocytes on the other hand originate from neural crest cells . As such, although morphologically and functionally similar, melanocytes and dendritic cells are not the same. Melanocytes are capable of expressing MHC Class II , a type of MHC expressed only by certain antigen presenting cells of the immune system, when stimulated by interactions with antigen or cytokines. All cells in any given vertebrate express MHC, but most cells only express MHC class I . The other class of MHC, Class II ,

3608-469: The 2000s, average stratospheric ozone decreased by approximately 4%, contributing an approximate 4% increase to the average UV intensity at the Earth's surface. Ozone depletion and the seasonal "ozone hole" have led to much larger changes in some locations, especially in the southern hemisphere. Suntans , which naturally develop in some individuals as a protective mechanism against the sun, are viewed by most in

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3696-569: The Earth's gravitational field and the projected shadow is measured on a flat, level surface. For objects wider than skulls or poles, the height and length are best measured relative to the same occluding edge. The most significant risk is at solar noon when shadows are at their minimum, and the Sun's radiation passes most directly through the atmosphere. Regardless of one's latitude (assuming no other variables), equal shadow lengths mean equal amounts of UV radiation. The skin and eyes are most sensitive to damage by UV at 265–275 nm wavelength, which

3784-568: The Sun but may also result from artificial sources, such as tanning lamps , welding arcs, or ultraviolet germicidal irradiation . It is the body's reaction to direct DNA damage from UVB light. This damage is mainly the formation of a thymine dimer . The damage is recognized by the body, which then triggers several defense mechanisms, including DNA repair to revert the damage, apoptosis and peeling to remove irreparably damaged skin cells, and increased melanin production to prevent future damage. Melanin readily absorbs UV wavelength light, acting as

3872-465: The Western world as desirable. Tanning has led to an increased exposure to UV radiation from both the natural sun and tanning lamps . Suntans can provide a modest sun protection factor (SPF) of 3, meaning that tanned skin would tolerate up to three times the UV exposure as pale skin. Sunburns associated with indoor tanning can be severe. The World Health Organization, American Academy of Dermatology, and

3960-409: 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 Co internal burns common. Beta burns tend to be shallow as beta particles are not able to penetrate deeply into

4048-414: The ability to repair DNA damaged by UV radiation. The risk of sunburn can be increased by pharmaceutical products that sensitize users to UV radiation. Certain antibiotics , oral contraceptives , antidepressants , acne medications , and tranquillizers have this effect. The UV Index indicates the risk of sunburn at a given time and location. Contributing factors include: Because of variations in

4136-490: The absorption spectrum of DNA points towards the formation of cyclobutane pyrimidine dimers (CPDs) - direct DNA damage . Typically, between 1000 and 2000 melanocytes are found per square millimeter of skin or approximately 5% to 10% of the cells in the basal layer of epidermis. Although their size can vary, melanocytes are typically 7 μm in length. Both lightly and darkly pigmented skin contain similar numbers of melanocytes, with difference in skin color due to differences

4224-552: The aircraft carrier USS  Bairoko received beta burns, and there was an increased cancer rate. During the Zebra test of the Operation Sandstone in 1948, three men had beta burns on their hands when removing sample collection filters from drones flying through the mushroom cloud ; their estimated skin surface dose was 28 to 149 Gy, and their disfigured hands required skin grafts . A fourth man showed weaker burns after

4312-412: The average site These sensitive sites often occur at biologically significant locations near genes . Sunburn causes an inflammation process that includes the production of prostanoids and bradykinin . These chemical compounds increase sensitivity to heat by reducing the threshold of heat receptor ( TRPV1 ) activation from 109 °F (43 °C) to 85 °F (29 °C). The pain may be caused by

4400-440: The best sunscreen protection is achieved by application 15 to 30 minutes before exposure, followed by one reapplication 15 to 30 minutes after exposure begins. Further reapplication is necessary after activities such as swimming, sweating, and rubbing. Recommendations are product dependent varying from 80 minutes in water to hours based on the indications and protection shown on the label. The American Academy of Dermatology recommends

4488-543: The beta burns may first manifest in 24–48 hours by itching and/or burning sensation that last for one or two days, sometimes accompanied by hyperaemia . After 1–3 weeks burn symptoms appear; erythema, increased skin pigmentation (dark colored patches and raised areas), followed by epilation and skin lesions . Erythema occurs after 5–15  Gy , dry desquamation after 17 Gy, and bullous epidermitis after 72 Gy. Chronic radiation keratosis may develop after higher doses. Primary erythema lasting more than 72 hours

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4576-567: The body. They can appear similar to sunburn. Unlike gamma rays, beta emissions are stopped much more effectively by materials and therefore deposit all their energy in only a shallow layer of tissue, causing more intense but more localized damage. On cellular level, the changes in skin are similar to radiodermatitis. The dose is influenced by relatively low penetration of beta emissions through materials. The cornified keratine layer of epidermis has enough stopping power to absorb beta radiation with energies lower than 70 keV. Further protection

4664-619: The bottom layer (the stratum basale ) of the skin's epidermis , the middle layer of the eye (the uvea ), the inner ear , vaginal epithelium , meninges , bones , and heart found in many mammals and birds . Melanin is a dark pigment primarily responsible for skin color . Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation . Melanocytes also have

4752-524: The dermis; modern radiotherapy electron beam accelerators take advantage of this. At yet higher energies, above 16 MeV, the effect does not show significantly anymore, limiting the usefulness of higher energies for radiotherapy. As a convention, surface is defined as the topmost 0.5 mm of skin. High-energy beta emissions should be shielded with plastic instead of lead, as high-Z elements generate deeply penetrating gamma bremsstrahlung . The electron energies from beta decay are not discrete but form

4840-559: The earlier Yoke test. 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

4928-513: The epidermis. They likely work in concert with both keratinocytes and Langerhans cells , both of which are also actively phagocytic , to contribute to the immune response. Tyrosine is the non-essential amino acid precursor of melanin. Tyrosine is converted to dihydroxyphenylalanine (DOPA) via the enzyme tyrosinase. Then DOPA is polymerized into melanin. The copper-ion based enzyme-catalyzed oxidative transformation of catechol derivative dopa to light absorbing dopaquinone to indole-5,6-quinone

5016-412: The epilation threshold for sheared sheep is between 23 and 47 Gy (2500–5000 rep ) and the threshold for normally wooled face is 47–93 Gy (5000–10000 rep), for thickly wooled (33 mm hair length) sheep it is 93–140 Gy (10000–15000 rep). To produce skin lesions comparable with contagious pustular dermatitis , the estimated dose is between 465 and 1395 Gy. The effects depend on both

5104-557: The fallout particles from their skin did not develop skin lesions. 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

5192-500: The following criteria in selecting a sunscreen: The eyes are also sensitive to sun exposure at about the same UV wavelengths as skin; snow blindness is sunburn of the cornea. Wrap-around sunglasses or the use by spectacle-wearers of glasses that block UV light reduce harmful radiation. UV light has been implicated in the development of age-related macular degeneration , pterygium and cataracts . Concentrated clusters of melanin, commonly known as freckles , are often found within

5280-468: The high skin doses that can be generated in the course of the intervention, some procedures have resulted in early (less than two months after exposure) and/or late (two months or more after exposure) skin reactions, including necrosis in some cases. Radiation dermatitis, in the form of intense erythema and vesiculation of the skin, may be observed in radiation ports. As many as 95% of patients treated with radiation therapy for cancer will experience

5368-539: The immune system, and are considered to be immune cells. Although the full role of melanocytes in immune response is not fully understood, melanocytes share many characteristics with dendritic cells : branched morphology; phagocytic capabilities; presentation of antigens to T-cells ; and production and release of cytokines . Although melanocytes are dendritic in form and share many characteristics with dendritic cells, they derive from different cell lineages. Dendritic cells are derived from hematopoietic stem cells in

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5456-435: The inflicted harm is often not immediately obvious. After sun exposure, the skin may turn red in as little as 30 minutes, but sunburn usually takes 2 to 6 hours. Pain is usually strongest 6 to 48 hours after exposure. The burn continues to develop for 1 to 3 days, occasionally followed by peeling skin after 3 to 8 days. Some peeling and itching may continue for several weeks. Ultraviolet radiation causes sunburns and increases

5544-628: The intensity and the energy of the radiation. Low-energy beta (sulfur-35, 170 keV) produces shallow ulcers with little damage to dermis, while cobalt-60 (310 keV), caesium-137 (550 keV), phosphorus-32 (1.71 MeV), strontium-90 (650 keV) and its daughter product yttrium-90 (2.3 MeV) damage deeper levels of the dermis and can result in chronic radiation dermatitis. Very high energies from electron beams from particle accelerators , reaching tens of megaelectronvolts, can be deeply penetrating. Conversely, megavolt-scale beams can deposit their energy deeper with less damage to

5632-493: The intensity of UV radiation passing through the atmosphere, the risk of sunburn increases with proximity to the tropic latitudes , located between 23.5° north and south latitude. All else being equal (e.g., cloud cover, ozone layer , terrain , etc.), each location within the tropic or polar regions receives approximately the same amount of UV radiation over a year. In the temperate zones between 23.5° and 66.5°, UV radiation varies substantially by latitude and season. The higher

5720-464: The iris. The tender skin of the eyelids can also become sunburned and can be especially irritating. The lips can become chapped (cheilitis) by sun exposure. Sunscreen on the lips does not have a pleasant taste and might be removed by saliva. Some lip balms (ChapSticks) have SPF ratings and contain sunscreens. The skin of the feet is often tender and protected, so sudden prolonged exposure to UV radiation can be particularly painful and damaging to

5808-421: 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" —caused by beta particles —are shallow surface burns, usually of skin and less often of lungs or gastrointestinal tract , caused by beta particles, typically from hot particles or dissolved radionuclides that came to direct contact with or close proximity to

5896-420: The latitude, the lower the intensity of the UV rays. Sun intensity in the northern hemisphere is greatest during May, June and July—and in the southern hemisphere, November, December and January. On a minute-by-minute basis, the amount of UV radiation depends on the Sun's angle. Ultraviolet radiation is easily determined by the height ratio of any object to the size of its shadow . Height is measured parallel to

5984-598: The latter being a risk especially for grazing animals. Lost hair begins regrowing in nine weeks and is completely restored in about half a year. The acute dose-dependent effects of beta radiation on skin are as follows: According to other source: As shown, the dose thresholds for symptoms vary by source and even individually. In practice, determining the exact dose tends to be difficult. Similar effects apply to animals, with fur acting as additional factor for both increased particle retention and partial skin shielding. Unshorn thickly wooled sheep are well protected; while

6072-502: The least capacity to burn. However, all skin types can develop sunburn. Fitzpatrick's skin phototypes: Age also affects how skin reacts to the sun. Children younger than six and adults older than sixty are more sensitive to sunlight. Certain genetic conditions, for example, xeroderma pigmentosum , increase a person's susceptibility to sunburn and subsequent skin cancers. These conditions involve defects in DNA repair mechanisms which decrease

6160-865: 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. Radiation dermatitis occurs to some degree in most patients receiving radiation therapy, with or without chemotherapy. There are three specific types of radiodermatitis: acute radiodermatitis, chronic radiodermatitis, and eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy. Radiation therapy can also cause radiation cancer. With interventional fluoroscopy, because of

6248-411: 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

6336-403: The most sensitive organ to beta radiation, even in doses far below maximum permissible dose. Safety goggles are recommended to attenuate strong beta. Careful washing of exposed body surface, removing the radioactive particles, may provide significant dose reduction. Exchanging or at least brushing off clothes also provides a degree of protection. If the exposure to beta radiation is intense,

6424-445: The overproduction of a protein called CXCL5 , which activates nerve fibers. Skin type determines the ease of sunburn. People with lighter skin tones and limited capacity to develop a tan after UV radiation exposure have a greater risk of sunburn. Fitzpatrick's Skin phototypes classification describes the normal variations of skin responses to UV radiation. Persons with type I skin have the greatest capacity to sunburn, and type VI have

6512-418: The packing of eumelanin into the melanosomes of keratinocytes : those in dark-toned skin are "packaged into peri-nuclear distributed, ellipsoid" melanosomes while those light-tone skin are "assembled into clustered small, circular melanosomes". There are also differences in the quantity and relative amounts of eumelanin and pheomelanin . Pigmentation including tanning is under hormonal control, including

6600-494: 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

6688-589: 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

6776-557: The potential to cause radiation burns if the exposure factors and exposure time are not appropriately controlled by the operator. A study of radiation-induced skin injuries has been performed by the Food and Drug Administration (FDA) based on results from 1994, followed by an advisory to minimize further fluoroscopy-induced injuries. The problem of radiation injuries due to fluoroscopy has been further investigated in review articles in 2000, 2001, 2009 and 2010. Beta burns are frequently

6864-629: 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

6952-471: The risk of three types of skin cancer: melanoma , basal-cell carcinoma and squamous-cell carcinoma . Of greatest concern is that the melanoma risk increases dose-dependently proportional to the number of a person's lifetime cumulative episodes of sunburn. An estimated 1/3 of melanomas in the United States and Australia could be prevented with regular sunscreen use. Sunburn is caused by UV radiation from

7040-403: The skin and damage DNA, thymidine dinucleotide (pTpT) fragments from damaged DNA will trigger melanogenesis and cause the melanocyte to produce melanosomes, which are then transferred by dendrites to the top layer of keratinocytes. The precursor of the melanocyte is the melanoblast . In adults, stem cells are contained in the bulge area of the outer root sheath of hair follicles . When

7128-513: 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. The survivors have atrophied skin which

7216-674: The sunblock's ability to suppress sunburn: The higher the SPF rating, the lower the amount of direct DNA damage. The stated protection factors are correct only if 2 mg of sunscreen is applied per square cm of exposed skin translates into about 28 mL (1 oz) to cover the whole body of an adult male. The recommended dose is much more than many people use in practice. Sunscreens function as chemicals such as oxybenzone and dioxybenzone (organic sunscreens) or opaque materials such as zinc oxide or titanium oxide (inorganic sunscreens) that mainly absorb UV radiation. Chemical and mineral sunscreens vary in

7304-460: The top of the foot. Protective measures include sunscreen, socks, or swimwear that covers the foot. Dietary factors influence susceptibility to sunburn, recovery from sunburn, and risk of secondary complications. Several dietary antioxidants , including essential vitamins, are effective in protecting against sunburn and skin damage associated with ultraviolet radiation, in both human and animal studies. Supplementation with Vitamin C and Vitamin E

7392-553: The use of X-ray filters . Chronic radiodermatitis, squamous and basal cell carcinomas may develop months to years after radiation exposure. Chronic radiodermatitis presents as atrophic indurated plaques, often whitish or yellowish, with telangiectasia, sometimes with hyperkeratosis . Eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy is a skin condition that occurs most often in women receiving cobalt radiotherapy for internal cancer. Radiation-induced erythema multiforme may occur when phenytoin

7480-567: The wavelengths of UV radiation blocked. Broad-spectrum sunscreens contain filters that protect against UVA radiation as well as UVB. Although UVA radiation does not primarily cause sunburn, it contributes to skin aging and increases skin cancer risk. Sunscreen is effective and thus recommended for preventing melanoma and squamous cell carcinoma . There is little evidence that it is effective in preventing basal cell carcinoma . Typical use of sunscreen does not usually result in vitamin D deficiency , but extensive usage may. Research has shown that

7568-495: Was itching and burning; in a day or two the sensations subsided, to be followed after 2–3 weeks by epilation and ulcers. Darker-colored patches and raised areas appeared on their skin, blistering was uncommon. Ulcers formed dry scabs and healed. Deeper lesions, painful, weeping and ulcerated, formed on more contaminated residents; the majority healed with simple treatment. In general, the beta burns healed with some cutaneous scarring and depigmentation. Individuals who bathed and washed

7656-459: Was shown in one study to reduce the amount of sunburn after a controlled amount of UV exposure. A review of scientific literature through 2007 found that beta carotene (Vitamin A) supplementation had a protective effect against sunburn. The effects of beta carotene were only evident in the long-term, with studies of supplementation for periods less than ten weeks in duration failing to show any effects. There

7744-456: Was supported by multiple studies. However, others have found aloe vera to have no effect. Note that aloe vera cannot protect people from new or further sunburn. Another home treatment is using a moisturizer that contains soy . Furthermore, sunburn draws fluid to the skin's surface and away from the rest of the body. Drinking extra water is recommended to help prevent dehydration . Radiation burn The most common type of radiation burn

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