Sunburn
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.
KEY TERMS
Antibiotics —Drugs that are designed to kill or inhibit the growth of the bacteria that cause infections.
Prophylaxis —Protection against or prevention of a disease. Antibiotic prophylaxis is the use of antibiotics to prevent a possible infection.
Stevens-Johnson syndrome —A severe inflammatory skin eruption that occurs as a result of an allergic reaction or respiratory infection.
Toxoplasmosis —A parasitic infection caused by the intracellular protozoan Toxoplasmosis gondii . Humans are most commonly infected by swallowing the oocyte form of the parasite in soil (or kitty litter) contaminated by feces from an infected cat; or by swallowing the cyst form of the parasite in raw or undercooked meat.
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 )
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.
KEY TERMS
Malignant melanoma —The most serious of the three types of skin cancer, malignant melanoma arises from the melanocytes, the skin cells that produce the pigment melanin.
Sunscreen —A product that blocks the damaging rays of the sun. Good sunscreens contain either para-aminobenzoic acid (PABA) or benzophenone, or both. Sunscreen protection factors range from two to 45.
Sunstroke —Heatstroke caused by direct exposure to the sun in which body temperature increases to dangerously high levels.
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: http://www.cancer.org.
WEB SITES
Guenther, Lyn, and Benjamin Barankin. "Sunburn." eMedicine Medical Library , October 27, 2004. Available online at http://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 http://www.emedicine.com/wild/topic71.htm (accessed December 1, 2004).
Tish Davidson, A.M. Carol A. Turkington