sunburn

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Definition

Inflammation of the skin caused by overexposure to the sun.

Description

Sunburn is caused by exposure to the ultraviolet (UV) rays of the sun. There are two types of ultraviolet rays, UVA and UVB. UVA rays penetrate the skin more deeply and can cause melanoma in susceptible people. UVB rays, which don't penetrate as deeply, cause sunburn and wrinkling. Most UVB rays are absorbed by sunscreens, but only about half the UVA rays are absorbed.

Skin cancer from sun overexposure is a serious health problem in the United States, affecting almost a million Americans each year. One out of 87 will develop malignant melanoma, the most serious type of skin cancer, and 7, 300 of them will die each year.

Fair-skinned people are most susceptible to sunburn, because their skin produces only small amounts of the protective pigment called melanin. People trying to get a tan too quickly in strong sunlight are also more vulnerable to sunburn. While they have a lower risk, even the darkest-skinned people can get skin cancer.

Repeated sun overexposure and burning can prematurely age the skin, causing yellowish, wrinkled skin. Overexposure can increase the risk of skin cancer, especially a serious burn in childhood.

— Carol A. Turkington

Inflammation or blistering of the skin caused by overexposure to direct sunlight.

To affect or be affected with sunburn.

Skin damage caused by overexposure to the sun's rays, especially ultraviolet rays. There are two main types of ultraviolet light, UVA (wavelengths 320-400 nm) and UVB (wavelengths 290-320 nm). On a dose-to-dose basis, UVB is about 1000 times more harmful than UVA. Exposure to ultraviolet light increases with altitude (4 per cent per 100 metres), increasing the risk of sunburn. Chronic exposure of unprotected skin to sunlight induces premature skin ageing, abnormal pigmentation, and skin cancers. Anyone exercising regularly out of doors has a high risk of sunburn and should use a sunscreen with a high sun-protection factor, which absorbs both UVA and UVB. Acute sunburn is treated with cold compresses and painkillers.

Definition

A sunburn is an inflammation or blistering of the skin caused by overexposure to the sun.

Description

Sunburn is caused by excessive exposure to the ultraviolet (UV) rays of the sun. There are two types of ultraviolet rays, UVA and UVB. UVA rays penetrate the skin deeply and can cause melanoma in susceptible people. UVB rays, which don't penetrate as deeply, cause sunburn and wrinkling. Most UVB rays are absorbed by sunscreens, but only about half the UVA rays are absorbed.

Skin cancer from sun overexposure is a serious health problem in the United States, affecting almost one million Americans each year. One person out of 87 will develop malignant melanoma, the most serious type of skin cancer, and 7,300 of them will die each year. The Environmental Protection Agency (EPA) reported in 2000 that the rate of malignant melanoma is rising faster in the United States than the rates of all other preventable cancers except lung cancer. One reason for this high rate is the popular belief that suntanned skin is healthy and attractive. Many people spend more time in the sun than is good for their skin trying to achieve a fashionable tan.

People with fair skin are most susceptible to sunburn, because their skin produces only small amounts of the protective black or dark brown pigment called melanin. However, people of any race can get sunburned if they do not protect their skin against overexposure. People trying to get a tan too quickly in strong sunlight are also more vulnerable to sunburn.

Repeated sun overexposure and burning can prematurely age the skin, causing yellowish, wrinkled skin. Overexposure, especially a serious burn in childhood, can increase the risk of skin cancer.

Causes & Symptoms

The ultraviolet rays in sunlight destroy cells in the outer layer of the skin, damaging tiny blood vessels underneath. When the skin is burned, the blood vessels dilate and leak fluid. Cells stop making protein. Their DNA is damaged by the ultraviolet rays. Repeated DNA damage can lead to cancer.

When the sun burns the skin, it triggers immune defenses which identify the burned skin as foreign. At the same time, the sun transforms a substance on the skin which interferes with this immune response. While this substance keeps the immune system from attacking a person's own skin, it also means that any malignant cells in the skin will be able to grow freely.

Sunburn causes skin to turn red and blister. Several days later, the dead skin cells peel off. In severe cases, the burn may occur with sunstroke (vomiting, fever, and fainting).

While overexposure to the sun is harmful, even fatal, no exposure means the body can't manufacture vitamin D, which is the only vitamin whose biologically active form is a hormone. Vitamin D is produced in the skin from the energy of the sun's UV rays. People at risk for vitamin D deficiency include alcoholics, non-milk drinkers, and those who do not receive much sunlight—especially those who live in regions that get little natural light. Dr. Sheldon Saul Hendles says that as more people use sunscreens and decrease exposure to the sun, they should make sure to have adequate dietary and supplementary sources of vitamin D. Sunscreen prevents the synthesis of the vitamin.

Diagnosis

Symptoms of sunburn may not appear until several hours after exposure. A deep pink skin color accompanied by a sensation of heat and burning indicates a mild sunburn. A red color with visible clothing lines, burning, itching, and stinging indicates a moderate burn. Bright red skin with blisters, fever, chills, and nausea indicates severe burn and medical help should be sought quickly.

Treatment

Over-the-counter preparations containing aloe (Aloe barbadensis) are an effective treatment for sunburn, easingpain and inflammation while also relieving dryness of the skin. A variety of topical herbal remedies applied as lotions, poultices, or compresses may also help relieve the effects of sunburn. Calendula (Calendula officinalis) is one of the most frequently recommended to reduce inflammation.

Other natural remedies include:

• Applying compresses dipped in cold water, one part skim milk mixed with four parts cold water, aluminum acetate antiseptic powder mixed with water, witch hazel, white vinegar, or baking soda mixed with water.
• Making a paste out of cornstarch and water, and applying directed to affected areas.
• Placing thin, cold slices of raw cucumber, potato, or apple on the burned areas.
• Making a soothing solution by boiling lettuce in water, strain, cool the water for several hours in the refrigerator, then use cotton balls to pat the liquid onto the skin.
• Applying tea bags soaked in cold water to burned eyelids.
• Soothing the burn with cool yogurt, then rinsing with a cold shower.

Another natural remedy that has been proposed for treating sunburn is gingko biloba extract. A Turkish study published in 2002 reported that gingko biloba appears to heal sunburned skin after exposure as well as protect against ultraviolet radiation before exposure. These findings, however, await confirmation by other researchers.

Allopathic Treatment

Aspirin can ease pain and inflammation. Tender skin should be protected against the sun until it has healed.

In addition, people suffering from sunburn may apply:

• calamine lotion
• sunburn cream or spray
• cool tap-water compresses
• colloidal oatmeal (Aveeno) baths
• dusting powder to reduce chafing

People who are severely sunburned should see a doctor, who may prescribe corticosteroid cream to speed healing and prescription pain medication. Topical corticosteroids that have been shown to be safe as well as effective in treating sunburn include methylprednisolone aceponate and hydrocortisone 17-butyrate.

Expected Results

Moderately burned skin should heal within a week. While the skin will heal after a sunburn, the risk of skin cancer increases with exposure and subsequent burns. Even one bad burn in childhood carries an increased risk of skin cancer.

Prevention

Sun Protection Education

Concern about the rising rate of melanoma in Europe, Australia, and the United States has led public health experts to recommend adding instruction about the importance of sun protection to elementary and junior high school programs. A 1999 cross-sectional study of boys and girls in all 50 states found that 83% of the students had at least one sunburn during the previous summer, with 36% reporting three or more episodes of sunburn. Only 34% used sunscreen. As of 1998, only 3.4% of schools in the United States had sun protection policies to protect students from excessive sun exposure during recess or athletic practice. A standardized program of sun protection education developed by the EPA in 2000 has been reported to be effective in changing students' attitudes toward tanning and the importance of using sunscreen.

Specific Preventive Measures

To prevent sunburn, everyone over the age of six months should use a water-resistant sunscreen with a sun protective factor (SPF) of at least 15. Apply at least an ounce of sunscreen 15–30 minutes before going outside. It should be reapplied every two hours (more often after swimming). Babies should be kept completely out of the sun for the first six months of life, because their skin is thinner than the skin of older children. Sunscreens have not been approved for infants. Some people are allergic to para-aminobenzoic acid (PABA), a major ingredient in sunscreen products. They should check all labels or consult a doctor prior to application.

In addition, people should follow these guidelines:

• Limit sun exposure to 15 minutes the first day, even if the weather is hazy; then slowly increase exposure daily.
• Reapply sunscreen every two hours (more often if swimming or perspiring heavily).
• Reapply waterproof sunscreen after swimming more than 80 minutes, after toweling off, or after perspiring heavily.
• Avoid exposure to the sun between 10 A.M. and 3 P.M.
• Use waterproof sunscreen on legs and feet, since sun rays can burn even through water.
• Wear an opaque shirt in water, because reflected rays are intensified.

Patients using a sunscreen rated lower than SPF 15 should note that simply applying more of the same SPF won't prolong allowed time in the sun. Instead, patients should use a higher SPF in order to safely lengthen their exposure time. A billed cap protects 70% of the face; a wide-brimmed hat is better. People at very high risk for skin cancer can wear clothing that blocks almost all UV rays, but most people can simply wear white cotton summer-weight clothing with a tight weave. As of 2001, the U.S. Food and Drug Administration requires all sunscreen makers to label their products as providing minimum, moderate, or high levels of sun protection.

Resources

Books

Blumenthal, Mark. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicine. Boston: Integrative Medicine Communications, 1999.

Orkin, Milton, Howard Maibach, and Mark Dahl. Dermatology. Norwalk, CT: Appleton & Lange, 1992.

Periodicals

Buller, D. B., A. C. Geller, M. Cantor, et al. "Sun Protection Policies and Environmental Features in US Elementary Schools." Archives of Dermatology 138 (June 2002): 771-774.

Duteil, L., C. Queille-Roussel, B. Lorenz et al. "A Randomized, Controlled Study of the Safety and Efficacy of Topical Corticosteroid Treatments of Sunburn in Healthy Volunteers." Clinical and Experimental Dermatology 27 (June 2002): 314-318.

Geller, A. C., M. Cantor, D. R. Miller, et al. "The Environmental Protection Agency's National SunWise School Program: Sun Protection Education in US Schools (1999-2000)." Journal of the American Academy of Dermatology 46 (May 2002): 683-689.

Geller, A. C., G. Colditz, S. Oliveria, et al. "Use of Sunscreen, Sunburning Rates, and Tanning Bed Use Among More Than 10 000 US Children and Adolescents." Pediatrics 109 (June 2002): 1009-1014.

Ozkur, M. K., M. S. Bozkurt, B. Balabanli, et al. "The Effects of EGb 761 on Lipid Peroxide Levels and Superoxide Dismutase Activity in Sunburn." Photodermatology, Photoimmunology and Photomedicine 18 (June 2002): 117-120.

Tyler, Varro. "Aloe: Nature's Skin Soother." Prevention 50 (April 1, 1998): 94-96.

Organizations

American Academy of Dermatology. 930 East Woodfield Rd., PO Box 4014, Schaumburg, IL 60168. (847) 330-0230. .

Environmental Protection Agency. Ten regional offices with region-specific addresses and phone numbers. .

[Article by: Ken R. Wells; Rebecca J. Frey, PhD]

Definition

Sunburn is an inflammation of the skin caused by overexposure to ultraviolet radiation from the sun.

Description

Sunburn is caused by exposure to the ultraviolet (UV) rays of the sun. There are two types of ultraviolet rays, UVA and UVB. UVB radiation causes most sunburn (about 85%). However, most UVB rays are absorbed by sunscreens, but only about half the UVA rays are absorbed.

Although sunburn itself is not a serious health problem in the short term, skin cancer from sun overexposure is in the early 2000s a growing problem in the United States. Both UVA and UVB radiation play a role in the development of a form of skin cancer called malignant melanoma. According to the American Cancer Society, melanoma accounts for only 4 percent of all skin cancer, but 79 percent of skin cancer deaths, or about 7,900 deaths annually in the United States. In addition, more than 1 million Americans develop nonmelanoma skin cancer each year, although deaths from this form of cancer are much more rare (about 1,000 per year).

Skin contains a protective pigment called melanin. The darker the skin tone, the more melanin is present. Fair-skinned people are most susceptible to sunburn, because their skin produces only small amounts of the melanin. However, even the darkest-skinned people can get sunburn and skin cancer.

Infants are most susceptible to sunburn and should be kept out of the sun at all times. Children are more susceptible than adults, and because of their outdoor activities get three times more sun exposure on average than adults. It is estimated that one-half to three-quarters of an individual's total number of lifetime sunburns occur in childhood and adolescence.

Long-term effects of repeated sun overexposure and burning can cause premature aging and wrinkling of the skin. Overexposure can increase the risk of skin cancer, especially a serious burn in childhood. Individuals at highest risk for developing melanoma are those who have intermittent severe (blistering) sunburns in youth or adolescence.

Occasionally an allergic response to a drug will cause a skin reaction resembling sunburn in the absence of sun exposure.

Demographics

Infants and children are more likely to get sunburned than adults. Individuals who live in areas where the climate is mostly sunny year round (Arizona, southern California) are at higher risk both for sunburn and skin cancer. Those living at high altitudes are also at higher risk. The chance of being sunburned increases about 4 percent or every 1,000 feet (300 meters) rise in altitude. Fair-skinned, pale, freckled individuals are more likely to get sunburned than individuals with darker skin. Sunburn is extremely common. One poll found that in the summer of 1997, 13 percent of children had developed a sunburn in the preceding week.

Causes and Symptoms

The ultraviolet rays in sunlight destroy cells in the outer layer of the skin, damaging tiny blood vessels underneath. When the skin is burned, the blood vessels dilate and leak fluid. Cells stop making certain proteins because their DNA is damaged by the ultraviolet rays. Repeated DNA damage can lead to cancer.

When UV rays burn the skin, immune system defenses that identify the burned skin as foreign are triggered. At the same time, the UV rays transform a substance on the skin that interferes with this immune response. While this keeps the immune system from attacking a person's own skin, it also means that any malignant (cancerous) cells in the skin will be able to grow freely.

Sunburn causes skin to turn red and blister. Symptoms appear from one to 24 hours after sun exposure and peak several days later, after which dead skin cells peel off. In severe cases, the burn may occur with sunstroke (vomiting, fever, and collapse). Severe cases of sunburn may require hospitalization.

When to Call the Doctor

The doctor should be called any time there are symptoms of heatstroke, dehydration, blurred vision (possible sun damage to the eyes), chills, fever, vomiting, or blistering associated with sun exposure.

Diagnosis

Sunburn is easily diagnosed by visual inspection of the skin. No laboratory tests are needed.

Treatment

In most cases, treatment involves making the sunburned person more comfortable. The individual should get out of the sun and protect tender skin against more sun exposure for at least one week. Pain can be treated with acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. Individuals with moderate sunburn over a large area should drink extra water to avoid dehydration. In addition, discomfort may be reduced by using the following:

• calamine lotion
• sunburn cream or spray
• cool tap water compress
• colloidal oatmeal baths
• moisturizer creams to reduce skin peeling

People who are severely sunburned should see a doctor who may prescribe corticosteroid cream to speed healing. Extreme sunburns that blister may require treatment in a hospital burn unit and intravenous fluids to prevent dehydration. Individuals who develop sunburn as the result of a drug reaction should see a doctor promptly.

Alternative Treatment

Over-the-counter preparations containing aloe (Aloe barbadensis) are an effective treatment for sunburn, easing pain and inflammation while also relieving dryness of the skin. A variety of topical herbal remedies applied as lotions, poultices, or compresses may also help relieve the effects of sunburn. Calendula (Calendula officinalis) is one of the most frequently recommended to reduce inflammation.

Prognosis

Short-term prognosis is excellent. Moderately burned skin should heal within a week. While the skin will heal after sunburn, the risk of skin cancer increases with exposure and subsequent burns. Even one bad burn in childhood carries an increased risk of skin cancer.

Prevention

Infants under the age of six months should be kept strictly out of the sun. Sunscreens have not been approved for use by infants. Everyone age six months and older should use a water-resistant sunscreen having a sun protective factor (SPF) of at least 15, with an SPF of 30 or more strongly recommended for children. Sunscreen should be applied 15–30 minutes before going outside, as it takes that long to bond effectively with the skin and become effective. Sunscreen should be reapplied every two hours (more often after swimming).

In addition, people should take the following steps:

• Limit sun exposure to 15 minutes the first day, even if the weather is hazy, slowly increasing exposure daily.
• Reapply waterproof sunscreen after swimming for more than 80 minutes, after toweling off, or after perspiring heavily, or every two hours if not swimming.
• Avoid the sun between 10 A.M. and 3 P.M. when the sun is strongest and most direct.
• Wear a hat or cap to protect the face.
• Use sunscreen when participating in snow activities such as skiing where sunlight is reflected off the snow.
• Wear an opaque shirt on water, because reflected rays are intensified.

Parental Concerns

Parents, concern about their child's sun exposure is usually influenced by their own experience with tanning and sunburn. Until the early 2000s, a tan was considered healthy rather than an increased cancer risk. Many adolescents still desire a tanned look but should be discouraged from as much sun exposure as possible. Those who insist on tanning should be encouraged to tan gradually and avoid burns.

See also Heat disorders.

Resources

Books

Auerbach, Paul S. "Acute Effects of Ultraviolet Radiation on Skin: Sunburn and Tanning." Wilderness Medicine,4th ed. St Louis, MO: Mosby, 2001.

Hill, David, et al. Prevention of Skin Cancer. London: Kluwer Law International, 2003.

McNally, Robert Aquinas. Skin Health Information for Teens: Health Tips about Dermatological Concerns and Skin Cancer Risks. Detroit, MI: Omnigraphics, 2003.

Organizations

American Cancer Society. 1599 Clifton Road, Atlanta, GA 30329. Web site: www.cancer.org.

Web Sites

Guenther, Lyn, and Benjamin Barankin. "Sunburn." eMedicine Medical Library, October 27, 2004. Available online at www.emedicine.com/ped/topic2561.htm (accessed December 1, 2004).

Takayesu, James K., and Randy P. Prescilla. "Sunburn." eMedicine Medical Library, April 28, 2003. Available online at www.emedicine.com/wild/topic71.htm (accessed December 1, 2004).

[Article by: Tish Davidson, A.M. Carol A. Turkington]

For more information on sunburn, visit Britannica.com.

Damage to the skin due to overexposure to the sun's rays. Sunburn may vary from a mild redness to wide-spread blistering. See also skin cancer, SPF.

Inflammation—an actual burn—of the skin caused by exposure to ultraviolet rays of the sun as it occurs in humans does not occur in animals. White pigs suffer most and may develop a chronic dermatitis along the back, some may lose the tips of the ears by sloughing. Called also primary phototoxicity. Dogs and cats, particularly those with unpigmented skin on the dorsum of the nose, eyelids, ears or groin, may develop a chronic actinic dermatitis. Fish in cultivation ponds show white patches on the top of the head and corneal cataracts. See also solar dermatitis.

• s. cells — dyskeratotic keratinocytes, either scattered or in a continuous band in the outer stratum spinosum, are characteristic of a sunburn lesion.

For other uses, see Sunburn (disambiguation).

Sunburn
Classification and external resources
A young man displaying a moderate sunburn. Note that the intensity of redness does not necessarily correspond to the degree of skin damage.[citation needed]
ICD-10	L55.
ICD-9	692.71
MeSH	D013471

This article may require copy-editing for grammar, style, cohesion, tone or spelling. You can assist by editing it now.  (February 2008)

A sunburn is a burn to living tissue such as skin produced by overexposure to ultraviolet (UV) radiation, commonly from the sun's rays. Usual mild symptoms in humans and animals are 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, although a minority of scientists argue that it may not effectively protect against malignant melanoma, which is either caused by a different part of the ultraviolet spectrum or, according to others, not caused by sun exposure at all.^[3][4] 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 skin photoprotectant pigment that is the skin's natural defense against overexposure. Importantly, sunburn and the increase in melanin production are both 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.^[5] Malignant melanoma may occur as a result of indirect DNA damage if the damage is not properly repaired. Proper repair occurs in the majority of DNA damage, and as a result not every exposure to UV results in cancer. The only cure for sunburn is slow healing, although some skin creams can help with the symptoms.

Contents 1 Cause 2 Sunburn and skin cancer 2.1 Controversy over sunscreen 3 Other risk factors 3.1 Location 3.2 Pharmaceutical products 3.3 Ozone depletion 3.4 Popularity of tanning 4 Symptoms 4.1 Variations 4.2 Duration 5 Protection 5.1 Skin 5.2 Eyes 6 Treatment 6.1 Topical applications 6.2 Oral medication 7 See also 8 Notes 8.1 References 9 External links

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 the UV-radiation from the sun. UV-radiation from artificial sources, such as welding arcs and the lamps used in sunbeds and ultraviolet germicidal irradiation, can also cause sunburn. 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-thymine dimer. The damage is recognized by the body, and it triggers several defense mechanisms. These include DNA repair to revert the damage and increased melanin production to prevent future damage. Melanin transforms UV-photons quickly into harmless amounts of heat without generating free radicals and is therefore an excellent photoprotectant against direct and indirect DNA damage.

On an evolutionary level, the sunburn may have developed as a warning signal that deters humans from sun seeking behaviour which induces infertility.^[6] Importantly it has been shown that protecting against sunburn with chemical sunscreens does not imply protection against other damaging effects of UV-radiation.^[7]

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

Sunburn and skin cancer

Ultraviolet B (UVB) radiation causes dangerous sunburns and increases the risk of two types of skin cancer: basal-cell carcinoma and squamous cell carcinoma.^[8][9]

Controversy over sunscreen

The statement that "sunburn causes skin cancer" is adequate when it refers to basal-cell carcinoma and squamous cell carcinoma. But it is false when it comes to malignant melanoma (see picture: UVR sunburn melanoma).^[10] The statistical correlation between sunburn and melanoma is due to a common cause — the UV-radiation. However, they are generated via two different mechanisms: direct DNA damage is ascribed by many medical doctors to a change in behaviour of the sunscreen user due to a false sense of security afforded by the sunscreen. (Other researchers blame insufficient correction for confounding factors; light skinned individuals versus indirect DNA damage.)

Topically applied sunscreens block the UV rays as long as they do not penetrate into the skin. This prevents sunburn, suntanning, and skin cancer. If however the sunscreen filter is absorbed into the skin it only prevents the sunburn but it increases the amount of free radicals which in turn increases the risk for malignant melanoma. The harmful effect of photoexcited sunscreen filters on living tissue has been shown in many photobiological studies.^{[11][12][13][14]} Whether sunscreen prevents or promotes the development of melanoma depends on the relative importance of the protective effect from the topical sunscreen and the harmful effects of the absorbed sunscreen.

The use of sunscreen is known to prevent the direct DNA damage that causes sunburn and the two most common forms of skin cancer, basal-cell carcinoma and squamous cell carcinoma.^[15] However, if sunscreen penetrates into the skin, it promotes the indirect DNA damages, which cause the most lethal form of skin cancer, malignant melanoma.^[16] This form of skin cancer is rare, but it is responsible for 75% of all skin cancer-related deaths. Increased risk of malignant melanoma in sunscreen users has been the subject of many epidemiological studies.^{[3][4][17][18][19][20][21]}

Other risk factors

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. Everything 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. The higher the latitude, the lower the intensity of the UV rays. 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.

Pharmaceutical products

Sunburn can also be caused by pharmaceutical products that sensitise some users to UV radiation. Certain antibiotics, oral contraceptives, and tranquillizers have this effect.^[22] People with fair hair and/or freckles generally have a greater risk of sunburn than others because of their lighter skin tone.^[23]

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.^[24] Incidence of skin cancer in Queensland, Australia has risen to 75 percent among those over 64 years of age by about 1990, presumably due to thinning of the ozone layer.^[25] However it was pointed out by Garland et al. that the melanoma rate in Queensland had 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 cannot obey the borderline of different areas of Australia, but sunscreen endorsement programs can.^[3] Another study from Norway points out that there had been no change of 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".^[26]

Popularity of tanning

Suntans, which naturally develop in some individuals as a protective mechanism against the sun, are viewed by many in the Western world as desirable.^[27] This has led to an increased exposure to UV-radiation from the natural sun and from solaria.

Symptoms

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

Sunburn caused by extended exposure on a glacier.

Other symptoms are edema, itching, peeling skin, rash, nausea and fever. 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.

One should immediately speak to a dermatologist if a skin lesion appears suddenly, with asymmetrical appearance, darker edges than center, that changes color, or becomes larger than 1/4 inch (6 mm). (see Melanoma)

Variations

Blisters on a shoulder caused by 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.

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.

Protection

Skin

Sunburn peeling. The dehydration of the epidermis causes the top layer to flake off.

It is advisable to consult a UV index to determine what level of protection is necessary. Potential forms of protection include wearing long-sleeved garments and wide-brimmed hats, and using an umbrella when in the sun. Minimization of sun exposure between the hours of 10 a.m. to 4 p.m. is also recommended. It is important to keep in mind that locations that use daylight saving time can have the most intense rays significantly later than 12 pm. Usually it will be around 1 pm, but in places like western Europe (where standard/winter time is already about an hour ahead of the sun, excluding the UK) DST/Summer Time can make it be later than 2 pm.

Sunburn, photographed 2 days after a 5-hour sun exposure. The dark red area is sunburned. The lighter-colored skin was covered by the woman's suit during exposure.

Commercial preparations are available that block UV light, known as sunscreens or sunblocks. They have a Sunburn 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.

A sunscreen rated SPF10 blocks 90% UVB (but only as long as it did not penetrate into the skin); an SPF20 rated sunscreen blocks 95%. It is best to use a broad spectrum sunscreen to protect against both UVA and UVB radiation. It is prudent to use waterproof formulations if one plans to engage in water-based activities. Modern sunscreens contain filters for UVA radiation as well as UVB. Note that the stated protection factors are only correct 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.

Contrary to the common advice that sunscreen should be reapplied every 2–3 hours, 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 the sun exposure begins. Further reapplication is only necessary after activities such as swimming, sweating, and rubbing.^[28] This varies based on the indications and protection shown on the label — from as little as 80 minutes in water to a few hours,1 depending on the product selected.

When one is exposed to any artificial source of occupational UV, special protective clothing (for example, welding helmets/shields) should be worn.

There is also evidence that common foods may have some protective ability against sunburn if taken for a period before the exposure.^[29] Beta-carotene and lycopene, chemicals found in tomatoes and other fruit, have been found to increase the skin's ability to resist the effects of UV light. In a 2007 study, after about 10–12 weeks of eating tomato-derived products, a decrease in sensitivity toward UV was observed in volunteers. Ketchup and tomato puree are both high in lycopene.^[30] Dark chocolate rich in flavonoids has also been found to have a similar effect if eaten for long periods before exposure.

Eyes

The eyes are also sensitive to sun exposure, and wrap-around sunglasses which block UV light should also be worn. UV light has been implicated in pterygium and cataract development. For example concentrated clusters of melanin, commonly known as freckles, are commonly found within the iris.

It has been argued that the optic nerve stimulates the pituitary gland to produce a hormone that triggers the melanocytes in the skin to make more melanin. When wearing sunglasses, less sunlight reaches the optic nerve which in turn causes less warning to be sent to the pituitary gland and thus less melanin is made. Since melanin is required in greater quantity, one might be limiting cells from producing a necessary compound to prevent the damaging effects of ultraviolet radiation, and thus increasing the chance of sunburn. ^[31]

Treatment

The most important aspect of sunburn care is to avoid exposure to the sun while healing and to take precautions to prevent future burns. The best treatment for most sunburns is time. Given a few weeks, they will heal; however, there are a number of treatments that help manage the discomfort or facilitate the healing process. Blistered skin, with or without open sores, should heal on its own, but consult appropriate sources for suggestions about whether or not you may need medical attention.

Topical applications

• Lidocaine or Benzocaine can be administered to the spot of injury and will generally negate most of the pain. Lidocaine and benzocaine are a popular FDA approved local anesthetic pain reliever for sunburns and available at most drugstores in the United States in the form of ointment or spray.

The pain and burning associated with a sunburn can be relieved with a number of different remedies applied to the burn site. The skin can be hydrated by applying topical products containing Aloe vera and/or vitamin E, which reduce inflammation. Hydrocortisone cream may also help reduce inflammation and itching.

Avoid the use of butter; This is a false remedy which can prevent healing and damage skin.^[32] When treating open sores caused by a sunburn, like any other open skin wound, it is best to avoid lotions or other directly-applied ointments. However, antibacterial solutions and gauze can prevent skin infections.

There are two home remedies which have been known to help. One method involves applying a clean washcloth soaked with cool (not cold) milk, in the form of a cold compress. In addition to the cool temperature, a protein film will form to soothe the pain and the lactic acid will help reduce inflammation.^[33] A solution of diluted white cider vinegar (approx. 1 cup in a tub of water) applied in a similar fashion may also ease pain.^[34]

Oral medication

Sunburns can cause headaches or a mild fever in addition to the pain, so an analgesic may be indicated.^[35] Acetaminophen can help to relieve the pain. Taking NSAIDs such as ibuprofen or naproxen may help to reduce pain and inflammation. Aspirin may also be used, but DO NOT give aspirin to children as can cause Reye's syndrome^[32]

See also

• Sun unit
• Hyperthermia (heat stroke)
• Windburn

Notes

1. ^ World Health Organization, International Agency for Research on Cancer "Do sunscreens prevent skin cancer" Press release No. 132, June 5, 2000
2. ^ World Health Organization, International Agency for Research on Cancer "Solar and ultraviolet radiation" IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 55, November 1997
3. ^ ^{a b c} Garland C, Garland F, Gorham E (1992). "Could sunscreens increase melanoma risk?". Am J Public Health 82 (4): 614–5. doi:10.2105/AJPH.82.4.614. PMID 1546792. http://www.ajph.org/cgi/reprint/82/4/614. 
4. ^ ^{a b} Westerdahl J, Ingvar C, Mâsbäck A, Olsson H (2000). "Sunscreen use and malignant melanoma". Int. J. Cancer 87 (1): 145–50. doi:10.1002/1097-0215(20000701)87:1<145::AID-IJC22>3.0.CO;2-3. PMID 10861466. 
5. ^ Sunburn at eMedicine
6. ^ "The evolution of human skin coloration". http://www.bgsu.edu/departments/chem/faculty/leontis/chem447/PDF_files/Jablonski_skin_color_2000.pdf. 
7. ^ 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: 99–105. doi:10.1093/jnci/86.2.99. PMID 8271307. 
8. ^ World Health Organization, International Agency for Research on Cancer "Do sunscreens prevent skin cancer" Press release No. 132, June 5, 2000
9. ^ World Health Organization, International Agency for Research on Cancer "Solar and ultraviolet radiation" IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 55, November 1997
10. ^ Davies H, Bignell GR, Cox C, et al. (2002). "Mutations of the BRAF gene in human cancer". Nature 417 (6892): 949–54. doi:10.1038/nature00766. PMID 12068308. http://www.nature.com/nature/journal/v417/n6892/full/nature00766.html. 
11. ^ Armeni T, Damiani E, Battino M, Greci L, Principato G (2004). "Lack of in vitro protection by a common sunscreen ingredient on UVA-induced cytotoxicity in keratinocytes". Toxicology 203 (1-3): 165–78. doi:10.1016/j.tox.2004.06.008. PMID 15363592. 
12. ^ Knowland J, McKenzie EA, McHugh PJ, Cridland NA (1993). "Sunlight-induced mutagenicity of a common sunscreen ingredient". FEBS Lett. 324 (3): 309–13. doi:10.1016/0014-5793(93)80141-G. PMID 8405372. http://linkinghub.elsevier.com/retrieve/pii/0014-5793(93)80141-G. 
13. ^ Mosley, C N; Wang, L; Gilley, S; Wang, S; Yu, H (2007). "Light-Induced Cytotoxicity and Genotoxicity of a Sunscreen Agent, 2-Phenylbenzimidazol in Salmonella typhimurium TA 102 and HaCaT Keratinocytes". Internaltional Journal of Environmental Research and Public Health 4 (2): 126–31. 
14. ^ Xu C, Green A, Parisi A, Parsons PG (2001). "Photosensitization of the sunscreen octyl p-dimethylaminobenzoate by UVA in human melanocytes but not in keratinocytes". Photochem. Photobiol. 73 (6): 600–4. doi:10.1562/0031-8655(2001)073<0600:POTSOP>2.0.CO;2. PMID 11421064. http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0031-8655&date=2001&volume=73&issue=6&spage=600. 
15. ^ Health Report - 13/09/99: Skin Cancer and Sunscreen
16. ^ Hanson KM, Gratton E, Bardeen CJ (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radic. Biol. Med. 41 (8): 1205–12. doi:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167. 
17. ^ Autier P, Doré JF, Schifflers E, et al. (1995). "Melanoma and use of sunscreens: an EORTC case-control study in Germany, Belgium and France. The EORTC Melanoma Cooperative Group". Int. J. Cancer 61 (6): 749–55. doi:10.1002/ijc.2910610602. PMID 7790106. 
18. ^ Weinstock MA (1999). "Do sunscreens increase or decrease melanoma risk: an epidemiologic evaluation". J. Investig. Dermatol. Symp. Proc. 4 (1): 97–100. doi:10.1038/sj.jidsp. PMID 10537017. 
19. ^ Vainio H, Bianchini F (2000). "Cancer-preventive effects of sunscreens are uncertain". Scand J Work Environ Health 26 (6): 529–31. PMID 11201401. http://www.sjweh.fi/show_abstract.php?abstract_id=578. 
20. ^ Wolf P, Quehenberger F, Müllegger R, Stranz B, Kerl H. (1998). "Phenotypic markers, sunlight-related factors and sunscreen use in patients with cutaneous melanoma: an Austrian case-control study.". Melanoma Res. 8 (4): 370–378. doi:10.1097/00008390-199808000-00012. PMID 9764814. 
21. ^ Graham S, Marshall J, Haughey B, et al. (1985). "An inquiry into the epidemiology of melanoma". Am. J. Epidemiol. 122 (4): 606–19. PMID 4025303. http://aje.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=4025303. 
22. ^ "Avoiding Sun-Related Skin Damage" - No longer available
23. ^ Sunburn-Topic Overview
24. ^ 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. p. 95-123. 
25. ^ Al Gore, "Earth in the Balance, Ecology and the Human Spirit"', 1992
26. ^ Moan J, Dahlback A (1992). "The relationship between skin cancers, solar radiation and ozone depletion". Br. J. Cancer 65 (6): 916–21. PMID 1616864. 
27. ^ Healthwise Incorporated (March 27). "Suntan". http://www.webmd.com/hw/health_guide_atoz/sts15336.asp?navbar=hw82391. Retrieved on 2006. 
28. ^ Diffey BL (2001). "When should sunscreen be reapplied?". J. Am. Acad. Dermatol. 45 (6): 882–5. doi:10.1067/mjd.2001.117385. PMID 11712033. 
29. ^ Stahl W, Sies H (2007). "Carotenoids and flavonoids contribute to nutritional protection against skin damage from sunlight". Mol. Biotechnol. 37 (1): 26–30. PMID 17914160. 
30. ^ Neukam K, Stahl W, Tronnier H, Sies H, Heinrich U (2007). "Consumption of flavanol-rich cocoa acutely increases microcirculation in human skin". Eur J Nutr 46 (1): 53–6. doi:10.1007/s00394-006-0627-6. PMID 17164979. 
31. ^ Sharon Moalem, Jonathan Prince. Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease. February 2007.
32. ^ ^{a b} MedlinePlus Encyclopedia Sunburn first aid
33. ^ "Sunburn Remedies". http://www.health911.com/remedies/rem_sunb.htm. 
34. ^ "Got Sunburn? Get Milk.". http://www.umdnj.edu/about/news_events/releases/07/r080907_GotSunburn_Get_Milk.htm. 
35. ^ Heathwise Incorporated (January 9, 2006). "Sunburn – Home Treatment". http://www.webmd.com/hw/skin_and_beauty/hw82649.asp?pagenumber=1. Retrieved on 2006-08-26. 

References

• Agar NS, Halliday GM, Barnetson RS, Ananthaswamy HN, Wheeler M, Jones AM (2004). "The basal layer in human squamous tumors harbors more UVA than UVB fingerprint mutations: a role for UVA in human skin carcinogenesis". Proc. Natl. Acad. Sci. U.S.A. 101 (14): 4954–9. doi:10.1073/pnas.0401141101. PMID 15041750. 

• Baron ED, Fourtanier A, Compan D, Medaisko C, Cooper KD, Stevens SR (2003). "High ultraviolet A protection affords greater immune protection confirming that ultraviolet A contributes to photoimmunosuppression in humans". J. Invest. Dermatol. 121 (4): 869–75. doi:10.1046/j.1523-1747.2003.12485.x. PMID 14632207. 

• Hall HI, Saraiya M, Thompson T, Hartman A, Glanz K, Rimer B (2003). "Correlates of sunburn experiences among U.S. adults: results of the 2000 National Health Interview Survey". Public Health Rep 118 (6): 540–9. PMID 14563911. 

• Haywood R, Wardman P, Sanders R, Linge C (2003). "Sunscreens inadequately protect against ultraviolet-A-induced free radicals in skin: implications for skin aging and melanoma?". J. Invest. Dermatol. 121 (4): 862–8. doi:10.1046/j.1523-1747.2003.12498.x. PMID 14632206. 
• NOAA UV-Index Summary with Data Graphs

External links

Find more about Sunburn on Wikipedia's sister projects: Definitions from Wiktionary

Textbooks from Wikibooks
Quotations from Wikiquote
Source texts from Wikisource
Images and media from Commons
News stories from Wikinews

Learning resources from Wikiversity

• WebMD: When to see a doctor
• Tips and facts to know before playing in the sun
• Information on Treating and Preventing Sunburn from The Skin Cancer Foundation
• Sunburn Damage to Trees and Plants: and Prevention
• Sun Protection Tips
• Protecting Kids from the Sun
• MedlinePlus Encyclopedia Sunburn
• MedlinePlus Encyclopedia Sunburn First Aid
• Avoid sunburn - calculate your personal safe sunbathing time online, based on skin type and UV-index
• UV Information
• Check UV Index In Your City
• Shade structures allow outdoor fun while mitigating burn risk
• Sunblock Iphone program Iphone program that uses gps to get positional UV index and suggest SPF

v • d • e Diseases of the skin and subcutaneous tissue (integumentary system) (L, 680-709) Infections Bacterial skin disease Staphylococcus (Staphylococcal scalded skin syndrome, Impetigo, Boil, Carbuncle) · Strep (Impetigo) · Corynebacterium (Erythrasma) Viral skin disease Wart · Molluscum contagiosum · Erythema infectiosum · Exanthema subitum · Herpes simplex (Herpetic whitlow) General Cellulitis (Paronychia) · Acute lymphadenitis · Pilonidal cyst · Pimple (Pustule) Bullous disorders acantholysis (Pemphigus, Transient acantholytic dermatosis) · Pemphigoid (Bullous, Cicatricial, Gestational) · Dermatitis herpetiformis Inflammatory Dermatitis and eczema Atopic dermatitis · Seborrhoeic dermatitis (Dandruff, Cradle cap) · Contact dermatitis (Diaper rash, Urushiol-induced contact dermatitis) · Erythroderma · Lichen simplex chronicus/Prurigo nodularis · Itch (Pruritus ani, Pruritus scroti, Pruritus vulvae) · Nummular dermatitis · Dyshidrosis · Pityriasis alba Papulosquamous disorders Psoriasis (Psoriatic arthritis) · Parapsoriasis (Pityriasis lichenoides et varioliformis acuta, Pityriasis lichenoides chronica, Lymphomatoid papulosis) · other pityriasis (Pityriasis rosea, Pityriasis rubra pilaris) · other lichenoid (Lichen planus, Lichen nitidus) Urticaria Dermatographic urticaria · Cold urticaria · Cholinergic urticaria · Solar urticaria Erythema Erythema multiforme/drug eruptions: Stevens-Johnson syndrome · Toxic epidermal necrolysis · Erythema nodosum Other erythema: Erythema annulare centrifugum · Erythema marginatum · Keratolytic winter erythema · Necrolytic migratory erythema · Erythema toxicum Radiation-related disorders Sunburn · actinic rays (Actinic keratosis, Actinic cheilitis) · Polymorphous light eruption (Acne aestivalis) · Radiodermatitis · Erythema ab igne Pigmentation/ Dyschromia hypopigmentation (Albinism, Vitiligo) · hyperpigmentation (Melasma, Freckle, Café au lait spot, Lentigo/Liver spot, Acanthosis nigricans, Acral acanthotic anomaly) Other skin keratosis/hyperkeratosis (Seborrheic keratosis, Callus) · other epidermal thickening (Ichthyosis acquisita, Palmoplantar keratoderma) skin ulcer (Pyoderma gangrenosum, Bedsore) Cutaneous Markers of Internal Malignancy (Florid cutaneous papillomatosis, acanthosis nigricans, sign of Leser-Trelat) atrophic (Lichen sclerosus, Acrodermatitis chronica atrophicans) necrobiosis (Granuloma annulare, Necrobiosis lipoidica) · other granuloma (Granuloma faciale, Pyogenic granuloma) cutaneous vasculitis (Livedoid vasculitis, Erythema elevatum diutinum) Connective tissues collagen disease: Keloid localized connective tissue disorders: Lupus erythematosus (Discoid lupus erythematosus, Subacute cutaneous lupus erythematosus) · Scleroderma/Morphea · Linear scleroderma · Calcinosis cutis · Sclerodactyly · Ainhum see also congenital, neoplasia

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - solforbrænding, solskoldethed
v. tr. - solbrænde
v. intr. - blive forbrændt i solen

Nederlands (Dutch)
zonnebrand

Français (French)
n. - coup de soleil
v. tr. - souffrir d'un coup de soleil
v. intr. - souffrir d'un coup de soleil

Deutsch (German)
n. - Sonnenbrand
v. - sich einen Sonnenbrand zuziehen

Ελληνική (Greek)
n. - ηλιόκαμα, έγκαυμα από έκθεση σε ηλιακή ακτινοβολία
v. - καίγομαι από τον ήλιο

Italiano (Italian)
scottatura

Português (Portuguese)
n. - queimadura do sol (f)
v. - queimar ao sol

Русский (Russian)
загар, солнечный ожог, загорать, обжигаться на солнце

Español (Spanish)
n. - quemadura de sol, bronceado, atezado
v. tr. - quemar o quemarse con el sol, tostar o tostarse con el sol
v. intr. - quemar o quemarse con el sol, tostar o tostarse con el sol

Svenska (Swedish)
n. - solbränna, svidande solbränna, solsveda
v. - bränna sig i solen

中文（简体）(Chinese (Simplified))
晒斑, 晒伤, 晒红, 晒黑, 晒伤皮肤, 晒红皮肤, 晒黑皮肤

中文（繁體）(Chinese (Traditional))
n. - 曬斑, 曬傷, 曬紅, 曬黑
v. tr. - 曬傷, 曬紅, 曬黑
v. intr. - 曬傷皮膚, 曬紅皮膚, 曬黑皮膚

한국어 (Korean)
n. - 햇볕에 탐, 햇볕에 탄 부분
v. tr. - 햇볕에 타다
v. intr. - 햇볕에 타게 하다

日本語 (Japanese)
n. - 日焼け, 日焼け色
v. - 日に焼く, 日に焼ける, 日焼けする

العربيه (Arabic)
‏(الاسم) حرق الشمس على الجلد (فعل) تحرقه الشمس‏

עברית (Hebrew)
n. - ‮השתזפות, כוויית-שמש‬
v. tr. - ‮צרבה, שזפה (שמש)‬
v. intr. - ‮השתזף, נכווה משיזוף‬

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