Sunburn

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.

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 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 collapse).

Diagnosis

Visual inspection and a history of exposure to the sun.

Treatment

Aspirin can ease pain and inflammation. Tender skin should be protected against the sun until it has healed. In addition, apply:

• calamine lotion
• sunburn cream or spray
• cool tap water compress
• 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.

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, poltices, or compresses may also help relieve the effects of sunburn. Calendula (Calendula officinalis ) is one of the most frequently recommended to reduce inflammation.

Prognosis

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

Everyone from age six months on should use a water-resistant sunscreen with a sun protective factor (SPF) of at least 15. Apply at least an ounce 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 older children. Sunscreens have not been approved for infants.

KEY TERMS

Malignant melanoma— The most deadly of the three types of skin cancer.

Sunscreen— Products which block the damaging rays of the sun. Good sunscreens contain either para-aminobenzoic acid (PABA) or benzophenone, or both. Sunscreen protection factors range from 2-45.

In addition, people should:

• limit sun exposure to 15 minutes the first day, even if the weather is hazy, slowly increasing exposure daily
• reapply sunscreen every two hours (more often if sweating or swimming)
• reapply waterproof sunscreen after swimming more than 80 minutes, after toweling off, or after perspiring heavily
• avoid the sun between 10 A.M. and 3 P.M.

• use waterproof sunscreen on legs and feet, since the sun can burn even through water
• wear an opaque shirt in water, because reflected rays are intensified

If using a sunscreen under SPF 15, 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 lengthen exposure safely. 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.

Resources

PERIODICALS

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

sunburn inflammation of the skin caused by actinic rays from the sun or artificial sources. Moderate exposure to ultraviolet radiation is followed by a red blush, but severe exposure may result in blisters, pain, and constitutional symptoms. As ultraviolet rays penetrate the skin, they break down collagen and elastin, the two main structural components of the skin, a process that results in the wrinkled appearance of sun-damaged skin. In addition, the sun damages the DNA of the exposed skin cells. In response, the cells release enzymes that excise the damaged parts of the DNA and encourage the production of replacement DNA (a process that can go wrong and result in skin cancer ). At the same time, the production of melanin increases, darkening the skin. Melanin, the pigment that gives skin its color, acts as a barrier to further damage by absorbing ultraviolet light. A suntan results from this attempt by the skin to protect itself. Light-skinned persons and infants are especially susceptible to ultraviolet rays because they lack sufficient protective skin pigment. Certain diseases and drugs may also increase photosensitivity.

Due to the increase in the incidence of skin cancer and the effects of ozone layer depletion, more attention is being placed on protecting the skin from the sun's ultraviolet rays with broad spectrum sunscreens or clothing. Broad spectrum sunscreens block both UVA and UVB rays (two of the three bands of ultraviolet radiation). The relative UVB protection of a sunscreen is indicated by its SPF (sun protection factor) number. A higher number indicates a sunscreen that is more effective in preventing sunburn, but it is UVA radiation that is more likely to cause cancer and skin aging. A broad spectrum sunscreen with an SPF of 30 or higher is generally recommended by dermatologists. Some products may contain opaque formulations of zinc oxide or titanium dioxide that physically block all rays.

sun·burn / ˈsənˌbərn/ • n. reddening, inflammation, and, in severe cases, blistering and peeling of the skin caused by overexposure to the ultraviolet rays of the sun. • v. (past and past part. -burned or -burnt ) (be sunburned) (of a person or bodily part) suffer from sunburn: most of us managed to get sunburnt. ∎  [usu. as adj.] (sunburned or sunburnt) ruddy from exposure to the sun: a handsome sunburned face. ∎  [intr.] suffer from sunburn: a complexion that sunburned easily.

sunburn Damage to skin caused by prolonged or unaccustomed exposure to sunlight. It varies in severity from redness and soreness to the formation of large blisters. Excessive exposure to sunlight is associated with the skin cancer known as melanoma.

sunburn (sun-bern) n. damage to the skin by excessive exposure to the sun's rays, principally UVB (see ultraviolet radiation). Sunburn may vary from reddening of the skin to the development of large painful fluid-filled blisters (see burn).

sunburn •adjourn, astern, Berne, burn, churn, concern, discern, earn, fern, fohn, kern, learn, Lucerne, quern, Sauternes, spurn, stern, Sterne, tern, terne, Traherne, turn, urn, Verne, yearn •Bayern • Blackburn • heartburn •Hepburn • Raeburn • Swinburne •Gisborne, Lisburn •sideburn • sunburn • Bannockburn •lady-fern • Vättern • extern •cittern, gittern •Comintern • taciturn •nocturn, nocturne •U-turn • upturn