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Sunburn

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Sunburn

Sunburn
Classification and external resources
A sunburnt back that was partially protected by a bathing suit top.
ICD-10 L55
ICD-9 692.71
MedlinePlus 003227
MeSH D013471

A sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, commonly from the sun. Normal symptoms in humans and other animals include red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV radiation can be life-threatening in extreme cases. Exposure of the skin to lesser amounts of UV radiation will often produce a suntan.

Excessive UV radiation is the leading cause of primarily non-malignant skin tumors.[1][2] Sunscreen is widely agreed to prevent sunburn and some types of skin cancer. Clothing, including hats, is considered the preferred skin protection method. Moderate sun tanning without burning can also prevent subsequent sunburn, as it increases the amount of melanin, a photoprotectant pigment that is the skin's natural defense against overexposure. Importantly, both sunburn and the increase in melanin production are triggered by direct DNA damage. When the skin cells' DNA is damaged by UV radiation, type I cell-death is triggered and the skin is replaced.[3]

Contents

  • Signs and symptoms 1
    • Variations 1.1
    • Duration 1.2
    • Skin cancer 1.3
  • Cause 2
    • Location 2.1
    • Medications 2.2
    • Ozone depletion 2.3
    • Popularity of tanning 2.4
  • Prevention 3
    • Skin 3.1
    • Eyes 3.2
    • Diet 3.3
  • Treatment 4
  • Notes 5
  • External links 6

Signs and symptoms

Sunburn caused by extended exposure on a glacier.
Blisters on a shoulder caused by sunburn.

Typically there is initial redness (erythema), followed by varying degrees of pain, proportional in severity to both the duration and intensity of exposure.

Other symptoms are edema, itching, peeling skin, rash, nausea, fever, chills, and syncope. Also, a small amount of heat is given off from the burn, caused by the concentration of blood in the healing process, giving a warm feeling to the affected area. Sunburns may be first- or second-degree burns.

Variations

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.

Duration

Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious.

After the exposure, skin may turn red in as little as 30 minutes but most often takes 2 to 6 hours. Pain is usually most extreme 6 to 48 hours after exposure. The burn continues to develop for 24 to 72 hours, occasionally followed by peeling skin in 3 to 8 days. Some peeling and itching may continue for several weeks.

Long-term low-intensity exposure to sunlight is known to cause significant aging of the skin; other health effects are not accurately known. A particular example with very noticeable ageing is that of a 69-year-old truck driver of Chicago, IL in the United States, who drove in the city for 28 years. A photograph of his face[4][5] shows a great deal of ageing on the left side, where he was exposed to sunlight all day, while the right side has the "taut, unblemished face of an apparently much younger man".[4][5] Window glass does not absorb UVA, which can penetrate the epidermis and upper layers of dermis. Chronic UVA exposure can cause photoageing: thickening of the epidermis and stratum corneum and destruction of elastic fibers; it can cause DNA mutations and toxicity which can lead to cancer, although less carcinogenic than UVB.

Skin cancer

Ultraviolet radiation causes sunburns and increases the risk of three types of skin cancer, melanoma, basal-cell carcinoma and squamous cell carcinoma.[1][2][6] Of greatest concern, is that the melanoma risk increases in a dose-dependent manner with the number of a person's lifetime cumulative episodes of sunburn.[7]

Cause

The cause of sunburn is the direct damage that a UV-B photon can induce in DNA (left). One of the possible reactions from the excited state is the formation of a thymine-thymine cyclobutane dimer (right). This kind of damage is responsible for only 8% of all melanoma.

Sunburn is caused by UV radiation, either from the sun or from artificial sources, such as welding arcs, the lamps used in sunbeds, and ultraviolet germicidal irradiation. It is a reaction of the body to the direct DNA damage, which can result from the excitation of DNA by UV-B 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 and increased melanin production to prevent future damage. Melanin readily absorbs UV wavelength light, acting as a photoprotectant. By preventing the disruption of bonds that higher energy photons can produce, it inhibits both direct alteration of DNA and generation of free radicals, thus indirect DNA damage.

The pain may be caused by overproduction of a protein called CXCL5, which activates nerve fibres.[8]

Experiments with mice found that protection against sunburn by chemical sunscreens does not necessarily provide protection against other damaging effects of UV radiation such as enhanced melanoma growth.[9]

UV radiation sunburn and melanoma. Statistical correlation vs causal connection.

Skin type determines the ease of sunburn. In general, people with fair hair and/or freckles have a greater risk of sunburn than others because of their lighter skin tone. Age also affects how skin reacts to sun: the skin of children younger than 6 and adults older than 60 is more sensitive to sunlight. Factors of sunburn include:[10]

  1. The time of day. Between 10am and 4pm daylight saving time, the sun's rays are the strongest. Even on a cloudy day, the sun's damaging UV light can pass through clouds.
  2. Proximity to reflective surfaces, such as water, white sand, concrete, snow, and ice. All of these reflect the sun's rays and can cause sunburns.
  3. The season of the year. The position of the sun on late spring and summer days can cause a more severe sunburn.
  4. Altitude. At a higher altitude it is easier to become burnt because there is less of the earth's atmosphere to block the sunlight. UV exposure increases about 4% for every 1000 ft (305 m) gain in elevation.
  5. Proximity to the equator (latitude). The closer to the equator, the more direct sunlight passes through the atmosphere. For example, the southern United States gets fifty percent more sunlight than the northern United States.
  6. The UV Index of the day, which shows the risk of getting a sunburn that day.

Location

Erythemal dose at three Northern latitudes
source: NOAA.

Because of variations in 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.), over the course of a full year, each location within the tropic or polar regions receives approximately the same amount of UV radiation. In the temperate zones between 23.5° and 66.5°, UV radiation varies by latitude and season. The higher the latitude, the lower the intensity of the UV rays. Intensity in the northern hemisphere is greatest during the months of May, June and July - and in the southern hemisphere, November, December and January. On a minute-by-minute basis, the amount of UV radiation is dependent on the angle of the sun. This is easily determined by the height ratio of any object to the size of its shadow. The greatest risk is at solar noon, when shadows are at their minimum and the sun's radiation passes more directly through the atmosphere. Regardless of one's latitude (assuming no other variables), equal shadow lengths mean equal amounts of UV radiation.

Medications

The risk of a sunburn can be increased by pharmaceutical products that sensitize users to UV radiation. Certain antibiotics, oral contraceptives, and tranquillizers have this effect.[11]

Ozone depletion

In recent years, the incidence and severity of sunburn has increased worldwide, especially in the southern hemisphere, because of damage to the ozone layer. Ozone depletion and the seasonal ozone hole have led to dangerously high levels of UV radiation in some locations.[12] Incidence of skin cancer in Queensland, Australia had risen to 75 percent among those over 64 years of age by about 1990, due, it is presumed, to thinning of the ozone layer.[13] It was pointed out by Garland et al. that the melanoma rate in Queensland had taken a steep rise before the rest of Australia experienced the same increase of melanoma numbers. They blamed the vigorous promotion of sunscreen, which was first done in Queensland, while sunscreen use was encouraged in the rest of Australia some time later. An effect that would stem from the ozone depletion could not differ from territory to territory within Australia, but sunscreen endorsement programs could.[14] Another study from Norway points out that there had been no change in the ozone layer during the period 1957 to 1984, yet the yearly incidence of melanoma in Norway had increased by 350% for men and by 440% for women. They concluded that in Norway "ozone depletion is not the cause of the increase in skin cancers".[15]

Popularity of tanning

Suntans, which naturally develop in some individuals as a protective mechanism against the sun, are viewed by most in the Western world as desirable.[16] This has led to increased exposure to UV radiation from both the natural sun and solaria.

Prevention

Skin

Sunburn effect (as measured by the UV Index) is the product of the sunlight spectrum (radiation intensity) and the erythemal action spectrum (skin sensitivity) across the range of UV wavelengths. Sunburn production per milliwatt is increased by almost a factor of 100 between the near UVB wavelengths of 315-295 nm
Sunburn peeling. The destruction of lower layers of the epidermis causes rapid loss of the top layers.
Another sunburn peeling.

One of the most effective ways to prevent sunburn is to reduce the amount of UV radiation reaching the skin. The strength of sunlight is published in many locations as a

External links

  1. ^ a b
  2. ^ a b
  3. ^ Sunburn at eMedicine
  4. ^ a b Unilateral Dermatoheliosis, Jennifer R.S. Gordon, M.D., and Joaquin C. Brieva, M.D., N Engl J Med 2012; 366:e25, 19 April 2012
  5. ^ a b Guardian newspaper: One face, but two sides of a story, 6 June 2012
  6. ^ "Facts About Sunburn and Skin Cancer", Skin Cancer Foundation
  7. ^ Sunburns and risk of cutaneous melanoma, does age matter: a comprehensive meta-analysis
  8. ^ J. M. Dawes, M. Calvo, J. R. Perkins, K. J. Paterson, H. Kiesewetter, C. Hobbs, T. K. Y. Kaan, C.Orengo, D. L.H. Bennett, S. B.McMahon, CXCL5 Mediates UVB Irradiation–Induced Pain. Sci. Transl. Med. 3, 90ra60 (2011). http://dx.doi.org/10.1126/scitranslmed.3002193
  9. ^ Wolf P; Donawho C K; Kripke M L (1994). "Effect of Sunscreens on UV radiation-induced enhancements of melanoma in mice.". J. Nat. Cancer. Inst. 86 (2): 99–105.  
  10. ^ "Sunburn – Topic Overview". Healthwise. November 15, 2013. Retrieved November 29, 2014. 
  11. ^ "Avoiding Sun-Related Skin Damage" - No longer available
  12. ^ van der Leun, J.C., and F.R. de Gruijl (1993). Influences of ozone depletion on human and animal health. Chapter 4 in UV-B radiation and ozone depletion: Effects on humans, animals, plants, microorganisms, and materials. pp. 95–123. 
  13. ^ Al Gore, "Earth in the Balance, Ecology and the Human Spirit"', 1992
  14. ^ Garland C, Garland F, Gorham E (1992). "Could sunscreens increase melanoma risk?". Am J Public Health 82 (4): 614–5.  
  15. ^ Moan J, Dahlback A (1992). "The relationship between skin cancers, solar radiation and ozone depletion". Br. J. Cancer 65 (6): 916–21.  
  16. ^ "Suntan". Healthwise. March 27, 2005. Retrieved August 26, 2006. 
  17. ^ Sun protection. World Health Organization.
  18. ^ Diffey BL (2001). "When should sunscreen be reapplied?". J. Am. Acad. Dermatol. 45 (6): 882–5.  
  19. ^ Kanavy HE, Gerstenblith MR (December 2011). "Ultraviolet radiation and melanoma". Semin Cutan Med Surg 30 (4): 222–8.  
  20. ^ Burnett ME, Wang SQ (April 2011). "Current sunscreen controversies: a critical review". Photodermatol Photoimmunol Photomed 27 (2): 58–67.  
  21. ^ Kütting B, Drexler H (December 2010). "UV-induced skin cancer at workplace and evidence-based prevention". Int Arch Occup Environ Health 83 (8): 843–54.  
  22. ^ Council on Environmental H, Section on, Dermatology, Balk, SJ (Mar 2011). "Ultraviolet radiation: a hazard to children and adolescents.". Pediatrics 127 (3): 588–97.  
  23. ^ Lin JS, Eder, M, Weinmann, S (Feb 2011). "Behavioral counseling to prevent skin cancer: a systematic review for the U.S. Preventive Services Task Force.". Annals of Internal Medicine 154 (3): 190–201.  
  24. ^ Norval, M; Wulf, HC (October 2009). "Does chronic sunscreen use reduce vitamin D production to insufficient levels?". The British journal of dermatology 161 (4): 732–6.  
  25. ^ Glazer-Hockstein, C; Dunaief JL (January 2006). "Could blue light-blocking lenses decrease the risk of age-related macular degeneration?". Retina 26 (1): 1–4.  
  26. ^ Solomon, AS (June 2006). "Pterygium". British Journal of Ophthalmology 90 (6): 665–666.  
  27. ^ Neale, RE; JL Purdie; LW Hirst; AC Green (November 2003). "Sun exposure as a risk factor for nuclear cataract".  
  28. ^ Eberlein-König, Bernadette; Placzek, Marianne; Przybilla, Bernhard (1998). "Protective effect against sunburn of combined systemic ascorbic acid (vitamin C) and d-α-tocopherol (vitamin E)". Journal of the American Academy of Dermatology 38 (1): 45–48.  
  29. ^ Köpcke, Wolfgang; Krutmann, Jean (2008). "Protection from Sunburn with β-Carotene—A Meta-analysis". Photochemistry and Photobiology 84 (2): 284–288.  
  30. ^ Stahl W, Sies H (2007). "Carotenoids and flavonoids contribute to nutritional protection against skin damage from sunlight". Mol. Biotechnol. 37 (1): 26–30.  
  31. ^ Maenthaisong R, Chaiyakunapruk N, Niruntraporn S, Kongkaew C (2007). "The efficacy of aloe vera used for burn wound healing: a systematic review". Burns 33 (6): 713–718.  
  32. ^ "Sunburn – Home Treatment". Healthwise. November 15, 2013. Retrieved November 29, 2014. 

Notes

The most important aspects of sunburn care are to avoid exposure to the sun while healing and to take precautions to prevent future burns. The best treatment for most sunburns is time. Most sunburns heal completely within a few weeks. Home treatments that help manage the discomfort or facilitate the healing process include using cool and wet cloths on the sunburned areas, taking frequent cold showers or baths, and applying soothing lotions that contain aloe vera[31] to the sunburn areas. Topical steroids (such as 1% hydrocortisone cream) may also help with sunburn pain and swelling. The peeling that comes after some sunburn is inevitable. However, there are lotions such as calamine that may relieve the itching. Paracetamol (acetaminophen in the US), non-steroidal anti-inflammatory drugs (such as ibuprofen or naproxen), and aspirin have all been shown to reduce the pain of sunburns.[32]

Treatment

Dietary factors influence susceptibility to sunburn, recovery from sunburn, and risk of secondary complications from sunburn. Several dietary antioxidants, including essential vitamins, have been shown to have some effectiveness for protecting against sunburn and skin damage associated with ultraviolet radiation, both in human and animal studies. Supplementation with Vitamin C and Vitamin E was shown in one study to reduce the amount of sunburn after a controlled amount of UV exposure.[28] A review of scientific literature through 2007 found that beta carotene (Vitamin A) supplementation had a protective effect against sunburn, but that the effects were only evident in the long-term, with studies of supplementation for periods less than 10 weeks in duration failing to show any effects.[29] There is also evidence that common foods may have some protective ability against sunburn if taken for a period before the exposure.[30]

Diet

The eyes are also sensitive to sun exposure at about the same wavelengths in the UV as skin. Wrap-around sunglasses or the use by spectacle-wearers of glasses that block UV light reduce harmful UV radiation. UV light has been implicated in the development of age-related macular degeneration,[25] pterygium[26] and cataract.[27] Concentrated clusters of melanin, commonly known as freckles, are often found within the iris.

Eyes

When one is exposed to any artificial source of occupational UV, special protective clothing (for example, welding helmets/shields) should be worn. Such sources can produce UVC, an extremely carcinogenic wavelength of UV which ordinarily is not present in normal sunlight, having been filtered out by the atmosphere.

Sunscreen is effective and thus recommended to prevent melanoma[19] and squamous cell carcinoma.[20] There is little evidence that it is effective in preventing basal cell carcinoma.[21] Other advice to reduce rates of skin cancer includes: avoiding sunburning, wearing protective clothing, sunglasses and hats, and attempting to avoid sun exposure or periods of peak exposure.[22] The U.S. Preventive Services Task Force recommends that people aged between 9 and 25 years of age be advised to avoid ultraviolet light.[23] Typical use of sunscreen does not usually result in vitamin D deficiency, but extensive usage may.[24]

Research has shown that the best 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 only after activities such as swimming, sweating, and rubbing.[18] This varies based on the indications and protection shown on the label — from as little as 80 minutes in water to a few hours, depending on the product selected.

Modern sunscreens contain filters for UVA radiation as well as UVB. The stated protection factors are correct only if 2 μL of sunscreen is applied per square cm of exposed skin. This translates into about 28 mL (1 oz) to cover the whole body of an adult male, which is much more than many people use in practice. Although UVA radiation does not cause sunburn, it does contribute to skin aging and an increased risk of skin cancer. Many sunscreens provide broad-spectrum protection, meaning that they protect against both UVA and UVB radiation.

Commercial preparations are available that block UV light, known as sunscreens or sunblocks. They have a Sun Protection Factor (SPF) rating, based on the sunblock's ability to suppress sunburn: The higher the SPF rating, the lower the amount of direct DNA damage.

The skin and eyes are most sensitive to damage by UV at 265-275 nm, which is in the lower UVC band where it is almost never encountered except from artificial sources like welding arcs. Most sunburn is caused by longer wavelengths simply because UV power is much greater there. For example, UV causes almost no sunburn at 315 nm at the extreme end of UVA, but causes 100 times more skin redness per unit of light, at 295 nm in the UVB band.

, this is not necessarily at 12 p.m., but often one to two hours later. daylight saving time Sunlight is generally strongest when the sun is close to the highest point in the sky. Due to time zones and [17]

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