The Sun and Skin

By Stephen M. Schleicher, MD, Director, DermDOX Center for Dermatology

We are a society that worships the sun. Bronzed skin has become a symbol of leisure and good health. Soaking up rays is one of our favorite pastimes. Very few experiences in life are more relaxing than lying on a glistening beach listening to the waves crash upon the shore as the bright sunlight beats down on us. And come nightfall, a glance in the mirror reveals the payoff of a day’s “work,” the suntan.

WARNING:   Dermatologists Have Determined that Excessive Sun Exposure Is Hazardous to Your Health!

Many of us express deep concern regarding the hazards of nuclear power, yet think nothing of basking all day in solar radiation. We have already learned that the sun’s ultraviolet rays damage the skin’s elastic tissues, leading to unsightly skin lines and wrinkles. The end result is premature aging and, for some, skin cancer. Each year, over one million cases of skin cancer are detected in the United States, where one person dies from skin cancer every hour. Ultraviolet light is responsible for the majority of skin cancers.

Besides the long-term effects attributed to chronic sun exposure, the damage wrought by sunlight may become apparent much sooner. Acute overexposure results in the painful, all-too-familiar sunburn.

SUNBURN

Virtually every light-skinned person has experienced sunburn at one time or another. Sunburn is a discomforting condition most frequently encountered at the beginning of summer before a protective tan has been acquired. Redheads and blonds burn readily; dark-skinned persons may sunburn, but only after prolonged exposure to strong sunlight. A recent study of fifteen thousand adults found that one-third had experienced a sunburn within the past year.

The extent of sunburn may range from a mild, painless redness to a fiery red, exquisitely tender, blistering eruption. A mild burn begins some six to twelve hours from the beginning of exposure, reaches a maximum redness within twenty-four hours, and gradually declines over the next few days, leaving in its wake tanned skin that may take some two weeks to reach its peak.

Severe sunburn also begins six to twelve hours following sun exposure, but within one to two days marked skin changes occur. The skin becomes extremely painful to even the slightest sensation. Chills, fever, and nausea are commonplace. Fluid-filled blisters appear, and layers of the skin begin to slough off. Uneven pigmentation and even scarring may result.

Mild sunburn reactions may be treated with cool water compresses. Emollient creams can soothe the skin and relieve dryness. Over-the-counter burn preparations contain local anesthetics that may help alleviate discomfort but will not enhance healing. Aspirin controls the pain and may even lessen the inflammation.

Severe sunburn should be treated by a physician. Cortisone pills and antibiotic creams are sometimes necessary to limit the inflammation and prevent infection.

SUN PROTECTION: How to Remain Safe in the Sun

Some dermatologists urge the avoidance of all nonessential sunlight whenever possible. Suntanning is frowned upon. Other dermatologists are a bit more lenient and recognize the psychosocial effects of the sun on certain individuals. The beneficial effects of sunlight on the body have recently received attention in the scientific and lay literature.

Six different skin types are defined. The lower your skin type number, the greater the risk of developing significant damage from exposure to sunlight or indoor tanning.

    Skin Type                  Sunburn & Tanning Traits                      

   I. Sensitive                    Always burns easily; never tans

   II. Sensitive                  Always burns easily; tans minimally

   III. Normal                    Burns moderately; tans gradually

   IV. Normal                    Burns minimally; always tans well

   V. Insensitive                Rarely burns; tans profusely

   VI. Insensitive               Never burns; deeply pigmented

The sunlight that reaches the earth consists of visible light and ultraviolet (UV) radiation; the invisible ultraviolet rays cause suntans and sun-induced skin injuries. The amount of ultraviolet light reaching the skin depends on a number of factors. For example, the lower the latitude, the greater the risk of sun damage to the skin at any given hour. A noontime sunbather in Miami will experience a heavier dose of burning rays than a noontime sunbather in Boston. The time of greatest risk anywhere in the world occurs in the middle of summer between the hours of 10 am and 2 pm.

Seasonal variations and altitude also play a role in the amount of ultraviolet light striking the skin. One will experience a more severe suntan in early May than at the end of August. The higher the altitude, the less atmosphere is present to filter out ultraviolet rays, a contributing factor to the marked sunburns often seen in winter skiers.

Environmental factors may also enhance one’s chances of sunburn. Beach sand, snow, and shiny metal (as in sun reflectors) markedly increase the dose of solar radiation. Other factors may fail to offer adequate protection. Water is not an efficient sun blocker; burning and tanning rays can penetrate beneath the surface of a pool. Many people sunburn on overcast days. Fooled by the lack of visible light, they do not take adequate protection, unaware that invisible ultraviolet radiation still reaches the skin. In fact, 70 percent of the sun’s rays penetrate clouds and fog.

Ultraviolet radiation is divided into UVA and UVB. UVA constitutes over 90 percent of the radiation penetrating to the earth’s surface. UVA can also penetrate the skin’s surface and has been implicated in suppression of the immune system. UVB causes damage to the epidermis, this resulting in the acute sunburn. Chronic ultraviolet light exposure induces wrinkles and other signs of cutaneous aging. UVB is filtered by window glass, but UVA is not.

A first line of defense against untoward ultraviolet light exposure is clothing, with some garments being much more effective than others. Indeed, certain clothes, especially when wet, fail to protect the skin from a significant portion of ultraviolet light. Color (darker shades being more efficient), fiber content, and fabric weave help determine clothing’s effectiveness as a barrier to ultraviolet light.

Individuals who are extremely sun sensitive or those who are at high risk for skin cancer would do best to wear specially formulated protective clothing when sun avoidance is not possible. Manufacturers include Coolibar and Solumbra. Another option is to wash clothes using the laundry additive Rit SunGuard which confers adequate UV light protection that lasts for about twenty washes.

And don’t forget a hat, especially if your hair is thinning. The hat protects not only the scalp, but depending on brim size, parts of the face as well.

Sun protective agents applied to the skin are known as sunscreens. These are widely available, formulated as creams, gels, lotions, sticks, pads, and sprays. Some ingredients work best to block UVA and have esoteric names such as avobenzone (Parsol 1789) and terephthalydene dicamphor sulfonic acid (Mexoryl SX). Others block UVB and have unpronounceable names such as octyl dimethyl para-aminobenzoic acid (PABA) and ethylhexyl p-methoxycinnamate. Agents that block both UVA and UVB are referred to as inorganic sunscreens and contain either titanium dioxide or zinc oxide.

Since both the ultraviolet A and ultraviolet B spectrums of light are dangerous to skin, one should always apply a sunscreen labeled “broad spectrum.”

Trendy additions to sunscreens include green tea and vitamins C and E. Antioxidants help block cell damage, but how effectively they work when applied to the skin has yet to be adequately determined.

For maximum effectiveness, sunscreens should be applied thirty minutes before sun exposure and reapplied after swimming or profuse sweating. A sunscreen labeled “water resistant” will adhere to the skin while the user is in water for forty minutes. One labeled “very water resistant” will adhere for eighty minutes. As a rule, most sunscreens lose their effectiveness after three or four hours.

The amount of sunscreen used is an important factor. One ounce (two tablespoons) is the minimal amount needed to cover the entire body. According to a 2007 study in the British Journal of Dermatology most people only apply one-quarter of the amount of sunscreen that they should.

Concerned about the growing incidence of sun-induced skin problems, as well as undocumented claims by certain manufacturers, the U.S. Food and Drug Administration advised in 1978 that sun protection factor (SPF) information be included on all sunscreen packages. Sunscreen products now carry numbers ranging from 15 to 50+ indicating their effectiveness in filtering out solar radiation capable of burning the skin. The higher the SPF number, the greater the degree of protection from UVB.

The SPF number provides a convenient way to calculate how long an individual can stay out in the sun without burning. Suppose that, with no tan at all, you can normally stay out in the sun ten minutes before getting burned. If you now use a product with an SPF of 15, you can stay out in the sun 150 minutes (10 ´ 15) without burning.

The higher the SPF number, the greater the shielding from burning radiation. This is not a linear relationship; an SPF of 30 does not give twice as much sun protection as an SPF of 15. SPF 15 blocks 93 percent of burning rays; SPF 30 blocks 97 percent; and SPF 50 blocks all but 1 percent.

Remember, SPF refers only to UVB radiation protection. Maximum sunscreen protection is afforded by a high-SPF, broad-spectrum formulation. This is important because UVA radiation has been linked to premature aging and skin cancer. And again, applying the correct amount of sunscreen is crucial. Using half of the correct amount of sunscreen rated at SPF 70 (that is, one tablespoon rather than two) will not give a SPF of 35, but one of 8.

 If used properly, sunscreens will prevent the immediate danger from solar radiation, the sunburn. Long-term use will help prevent wrinkles, dark spots, and cancer. Because the hazardous effects of sunlight are cumulative, sunscreens are best used at an early age—the earlier the better.

Indoor Tanning

Melanoma is the second most common cancer among American women in their twenties, and the rate of new melanoma cases in younger women has soared, increasing by 50 percent since 1980, although it has not increased for younger men. Younger women are much more likely to frequent tanning salons than younger men.

In 2009, Cancer Research United Kingdom, the UK’s leading cancer organization, reported that melanoma is now the most common cancer in young British women. Given the infamous dreary weather, this increased incidence is in large part attributed to tanning salons. Data indicates that women under thirty-five who use sunbeds increase their risk of developing melanoma by an astounding 75 percent. Note that high-pressure sunlamps can emit over ten times the UVA dose as the amount received from the sun.

The Indoor Tanning Association has taken an aggressive role to promote tanning using vitamin D as the cornerstone of an argument whose underlying basis is that a tan is healthy. Print ads have claimed that “scientists have proven that exposure to all forms of ultraviolet light—both indoors and out—stimulates the natural production of vitamin D. And research has proven that vitamin D protects against heart disease and many types of cancer.” Better to chew Viactivs. The Department of Health and Human Services has deemed ultraviolet light a known carcinogen (cancer-promoting agent).

Those in our society who need vitamin D the most—African Americans (because black skin has difficulty manufacturing this vitamin) and the elderly—are not very likely to visit tanning salons. And teenagers (and, for that matter, adults as well) do not frequent indoor tanning booths to obtain vitamin D, nor should they.

TANOREXIA

The concept that UV tanning is actually addictive has gained ground over the past several years, and the condition has been given the name tanorexia. A 2006 study demonstrated that frequent tanners experience withdrawal symptoms when UV tanning is abruptly discontinued. A 2007 study of college students noted that 12 percent of those interviewed (22 percent of the women and 8 percent of the men) showed evidence of a UV light-substance-related disorder. Despite awareness of the dangers of tanning, many still believe that tanner people are better-looking.

SELF-TANNERS

Scores of self-tanning formulations are available on the market for those seeking to look tan. The first self-tanning product was introduced way back in 1960, Coppertone QT (Quick Tanning) lotion. The problem? Rather than look golden brown, users tended to resemble aged pumpkins. Fortunately, shades are now quite realistic and pleasing. This fact, coupled with increased public awareness of the dangers of ultraviolet light, have contributed to the soaring popularity of these products.

The most effective sunless tanning gels, lotions, and sprays contain an ingredient called dihydroxyacetone (DHA), a colorless sugar that stains the cells in the top layer of the epidermis. DHA is the only agent currently approved by the FDA for this purpose. Stained cells are already dead and slough off in about five to seven days, hence the need for reapplication. Most commercial products contain a mixture of DHA, bronzers (water-soluble dyes that temporarily stain skin), and moisturizers. DHA does appear to be safe long-term when used on the skin surface, with low incidence of allergic reactions. Keep in mind that most products containing DHA offer no—or, at best, inadequate—sun protection, and that stained skin remains vulnerable to ultraviolet damage.

Tan accelerators are said to lessen the exposure time needed to bronze skin. Many contain the amino acid tyrosine, and all require ultraviolet light for activation. The FDA is “not aware of any data demonstrating that tyrosine or its derivatives are effective in stimulating the production of melanin.” (Stimulation of melanin is what produces a suntan.)

Oral “tanning pills” typically contain the substance canthaxanthin, which is FDA approved as a food-coloring agent. In high quantities the compound is deposited in the skin. But it is also deposited in the liver and eyes and can lead to hepatitis and cataracts. Canthaxanthin as a tanning agent is now banned in the United States but is available via the Internet.

SAD

 No doubt, when the sun doesn’t shine, many of us become depressed. This is termed SAD (seasonal affective disorder), and the features are depression, lack of energy, and an increased need for sleep. The mildest form is known by most as “winter blues.” About 75 percent of those affected are women, and the most common age of onset is in the mid-thirties. SAD is believed to affect fifteen million Americans, and perhaps another thirty million display some symptoms. The treatment of choice is bright light—the visible kind—not ultraviolet. And the light does no good striking the skin; it must be visualized by the eye.

True, SAD may be treated in the middle of winter in NYC with a bright white light source, but one can surmise that, if given as an option, Florida beach therapy would get the nod hands (if not buns) down. If you are lucky enough to fulfill this option, remember—especially if you are fair-skinned or have a personal or family history of skin cancer—to protect body parts from dangerous ultraviolet rays.

More on Vitamin D

Vitamin D helps the body absorb calcium and maintain adequate levels of calcium in the blood stream; both tasks are necessary for maintaining health bones. Vitamin D is the most commonly supplemented vitamin, added to milk, bread, and orange juice. Sun or exposure to ultraviolet light of the B range induces skin cells to manufacture vitamin D. The amount produced depends on a number of factors including exposure time, altitude, latitude, extent of skin surface exposed, time of year, and skin pigmentation (the darker or more tanned the skin, the less produced). Use of a high-SPF sunscreen limits or even prevents the skin from forming vitamin D.

Vitamin D deficiency can lead to bone diseases, including osteoporosis. Recent research suggests that higher levels of vitamin D may protect against prostate, colorectal, and breast cancers, and may help regulate blood pressure. Many persons do not obtain the minimal amounts of this vitamin. By advocating strict sun protection to avoid skin cancer, are doctors limiting an important source of a very important vitamin?

Vitamin D levels can be measured, and medically supervised oral supplementation will prevent deficiency. Studies suggest that relatively small amounts of sun exposure, ten to fifteen minutes on sunscreen-free hands, face, and arms two to three times a week are sufficient to maintain adequate levels. So, a little sun should go a long way.