Help Patients Get Serious About Sunscreens

Carol Potera

THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 5 - MAY 97

Sunscreens are vital for avoiding skin damage from the sun. Unfortunately, many people don't get the complete benefits of sunscreens because they misuse or misunderstand the products. Physicians who talk to patients about skin protection can dispel myths about sunscreens and advise patients about how to correctly select and use the products.

Do your patients know what "SPF" stands for? The term has been used for 20 years, but a recent survey (1) by the Washington, DC-based Cosmetic, Toiletry, and Fragrance Association suggests that many Americans are in the dark about sun protection.

The group's survey of 235 women showed that half were confused about the meaning of the terms listed on sunscreen labels: SPF (sun protection factor), UVA (ultraviolet A), and UVB (ultraviolet B). This doesn't surprise Daniel M. Siegel, MD, director of dermatologic surgery at the School of Medicine, State University of New York at Stony Brook. "The average person doesn't know what number sunscreen they use and why," he says.

The number following SPF is a multiplier of the time it ordinarily takes skin to burn, notes Siegel. If sunburn occurs after 10 minutes without sunscreen, an SPF 15 sunscreen delays burning to 150 minutes. The two skin-damaging wavelengths of ultraviolet radiation, UVB (290 to 320 nm) and UVA (320 to 400 nm), promote skin cancer by damaging DNA and suppressing the immune response. Sunscreens block ultraviolet radiation (2).

Risks of Underuse

Dermatologists say sunscreens are not foolproof. Most people don't slather on enough. For complete coverage, adult sunbathers need 1 oz, but typically apply a quarter as much (3). Key body areas, like the ears and back, often get missed. And sunscreens are sweated, rubbed, and washed off.

Psychology poses other problems. Tan-is-beautiful attitudes still prevail despite pale-is-beautiful campaigns. In one survey (4), 98% of respondents knew that ultraviolet radiation causes skin cancer, but 72% said a tan was more attractive than pale skin. Researchers who analyzed tanning trends in fashion magazines between 1983 and 1993 found only modest gains in sun safety awareness (5). Sunscreens lull some into a false sense of security so that they stay in the sun longer (6).

For such reasons, the incidence of melanoma has climbed 4% each year since 1973 (7), and the incidences of basal and squamous cell carcinoma increased 50% between 1980 and 1990 (2). The catchy Australian skin cancer awareness slogan, "slip, slop, slap," meaning slip on a shirt, slop on sunscreen, and slap on a hat, should be adopted everywhere (8), says dermatologist Leonard H. Goldberg, MD, chief of Mohs surgery at Baylor College of Medicine in Houston. Goldberg, in a recent report in The Lancet (8), attributes the rise in the incidence of basal cell carcinoma to the post-World War II increase in leisure time spent in the sun and near the water. "Basal cell carcinoma doesn't spread to the bloodstream and lymph nodes like melanoma, so it's not as deadly," says Goldberg. "However, it does grow in size and destroy normal tissue."

Advice for Active Patients

Sunscreens fall into two categories: chemical sunscreens that absorb ultraviolet radiation and physical sunscreens that scatter or reflect ultraviolet radiation. Some sunscreen products, such as DuraScreen 30 (Reed & Carnrick, Piscataway, New Jersey) and Hawaiian Tropic 45 Plus Sunblock (TRL, Inc, Ormond Beach, Florida), contain both types of protectants. Examples of chemical sunscreens include para-aminobenzoic acid esters, salicylates, and cinnamates.

Physical sunscreens containing zinc oxide or titanium dioxide are less allergenic (2,9). These substances, once familiar as the white gunk coating lifeguards' noses, have been pulverized and made relatively invisible in products such as Neutrogena Chemical-Free Sunblock and Sundown Sport Sunblock (Johnson & Johnson Consumer Pharmaceuticals Co, Fort Washington, Pennsylvania). Sweatproof ingredients in Neutrogena Sunblock (Johnson & Johnson) and Coppertone Sport (Schering-Plough Healthcare Products, Inc, Liberty Corner, New Jersey) stop them from running into the eyes and stinging (2). Sunscreens are available in creams, lotions, gels, wax sticks, and sprays.

To better advise his active patients, Siegel personally tests how well sunscreens stay on during his sweaty racquetball sessions. "I rub it on my forehead. If it runs in my eyes, it doesn't pass."

When patients ask which sunscreen to choose, Goldberg stays away from blanket recommendations and urges them to select a sunscreen with an SPF of at least 15. "They may try out different brand names from a bag containing 10 to 20 sunscreens, which we give to patients. They try them and find one that works for them," he says. For more sunscreen advice for patients, see table 1.

Table 1. Tips for Becoming a Savvy Sunscreen User

Use a sunscreen that has a sun protection factor (SPF) of 15 or higher; an SPF 15 sunscreen blocks 95% of the sun's most harmful wavelengths.
Select a sunscreen that blocks both harmful ultraviolet wavelengths: UVA and UVB.
Shake the sunscreen before you use it.
Wear sunscreen even on cloudy days and when in water.
Remember to wear sunscreen when near water or snow and at high altitudes.
Apply 1 ounce of sunscreen for whole-body coverage, and reapply often if you're sweaty or wet.
Remember to apply sunscreen to the areas many people forget: around the eyes, ears, mouth, and on the head if you are bald or have thin hair.
Reapply sunscreen hourly if you're swimming.
Take special care to protect babies and children with sunscreen, hats, shirts, or other barriers. Most people get 80% of their lifetime sun exposure before age 18.
Try several sunscreen brands to find the one that works best for your skin and your activities.

Sunscreen is only part of a complete sun protection program, says Siegel. Covering up is important, too. "The main thing for athletes is to wear shirts. Men don't wear shirts, and women wear halters," he says. "Melanoma is common on the back, and I see more melanoma on the back in younger people."

Clearing Up Myths

Dermatologists are finding that their advice to patients about sunscreen use is sometimes thwarted by the following patient misconceptions about the products.

Myth 1: Wearing sunscreen causes overheating during exercise. When 22 male students, thickly coated with a physical SPF 15 sunscreen, exercised vigorously for 45 minutes in 90°F temperatures, their skin temperatures were lower than when exercising without sunscreen (10). Core temperatures were lower but the change was not statistically significant.

Myth 2: Cloudy days and water submersion eliminate the need for sunscreen. Up to 80% of ultraviolet radiation penetrates cloud cover, and up to 50% reaches swimmers in water. Water-resistant and waterproof formulations resist water for 40 to 80 minutes (2).

Myth 3: SPF values greater than 15 are overkill. An SPF 30 sunscreen is significantly superior to an SPF 15 sunscreen at preventing early DNA damage to skin cells (11). High SPF values compensate for sweating, loss in the water, and thin application (12).

Myth 4: Sunscreens cause allergic reactions. The 1% to 2% of people allergic to sunscreens react mostly to fragrances, preservatives, and other substances, not the sun-blocking active ingredients (9).

Myth 5: Clothing or hats are as good as sunscreens. Loosely woven fabrics transmit up to 30% of ultraviolet radiation, and wet fabrics increase transmission. A white T-shirt has an SPF of 5 to 9 (2). Ultraviolet-protective fabrics raise the SPF to 30 (13). Forget baseball caps; hat brims need to be at least 3 in. wide all around to protect the entire head (14).

Myth 6: Sunscreens should be discarded each year because they deteriorate. Unless a sunscreen smells foul, "I keep it for several years," says Siegel. The active ingredients "last forever," says J. Michael Wentzell, MD, head of dermatologic surgery at the Billings Clinic in Montana. "Just remember to shake them up because they settle out."

New On the Horizon?

Products that combat sun damage account for much of the cosmetic industry's annual $14 billion business, and there are more than 150 brands on the market (2). Given consumer demand, it is no surprise that researchers and manufacturers are in hot pursuit of better sunscreens. One new product, called Ocean Secret (Applied Genetics, Inc, Freeport, New York), claims not only to block ultraviolet radiation, but also to repair sun damage to the DNA in skin cells, according to product literature. Enzymes extracted from marine plankton, which are continuously bombarded by ultraviolet radiation, are encapsulated into liposomes in Ocean Secret. In skin that was exposed to ultraviolet radiation and then treated with the enzymes contained in Ocean Secret, one marker of DNA damage was reduced by 50% (15). Ocean Secret is sold through dermatologists or can be ordered at (800) 590-4244.

Goldberg and Siegel say they're eager to see more scientific studies on Ocean Secret before recommending it. The product is currently classified by the US Food and Drug Administration as a cosmetic, unlike most sunscreens, which are classified as over-the-counter medications and therefore are tested more rigorously. "Ocean Secret is a different approach, and there is a need for better sunscreens," says Siegel. "But I'd like to see the patent and documentation behind it."

An old folk remedy may someday also have new life as a sunscreen. Aloe in a highly concentrated, pure form prevents immune suppression by ultraviolet radiation in mice (16). If it protects humans, too, aloe may end up in sunscreens, says researcher Faith Strickland, PhD, assistant professor of immunology at MD Anderson Cancer Center in Houston. Aloe is currently found in some sunscreens, but Strickland says it's too diluted to be protective, and the agents in aloe that prevent ultraviolet-induced immunosuppression are destroyed by most processing methods.

References

OTC Sunscreen Drug Products. Food and Drug Administration Docket No. 78N-0038
Wentzell JM: Sunscreens: an ounce of prevention. Am Fam Physician 1996;53(5):1713-1719
Bech-Thomsen N, Wulf HC: Sunbathers' application of sunscreen is probably inadequate to obtain the sun protection factor assigned to the preparation. Photodermatol Photoimmunol Photomed 1992-93;9(6):242-244
Berwick M, Fine JA, Bolognia JL: Sun exposure and sunscreen use following a community skin cancer screening. Prev Med 1992;21(3):302-310
George PM, Kuskowski M, Schmidt C: Trends in photoprotection in American fashion magazines, 1983-1993: will fashion make you look old and ugly? J Am Acad Dermatol 1996;34(3):424-428
Garland CF, Garland FC, Gorham ED: Could sunscreens increase melanoma risk? Am J Public Health 1992;82(4):614-615
Salopek TG, Marghoob AA, Slade JM, et al: An estimate of the incidence of malignant melanoma in the United States. Dermatol Surg 1995;21(4):301-305
Goldberg LH: Basal cell carcinoma. Lancet 1996;347(9002):663-667
Foley P, Nixon R, Marks R, et al: The frequency of reactions to sunscreens: results of a longitudinal population-based study on the regular use of sunscreens in Australia. Br J Dermatol 1993;128(5):512-518
Connolly DA, Wilcox A: The effects of an application of sunscreen on selected physiological variables during exercise in the heat. Med Sci Sports Exerc 1995;24(5):S107
Kaidbey KH: The photoprotective potential of the new superpotent sunscreens, abstracted. J Am Acad Dermatol 1990;22(3):449-452
Kaminester LH: Current concepts: photoprotection. Arch Fam Med 1996;5(5):289-295
Menter JM, Hollins TD, Sayre RM, et al: Protection against UV photocarcinogenesis by fabric materials. J Am Acad Dermatol 1994;31(5):711-716
Diffey BL, Cheeseman J: Sun protection with hats. Br J Dermatol 1992;127(1):10-12
Krutmann J, Ahrena C, Roza L, et al: The role of DNA damage and repair in ultraviolet B radiation-induced immunomodulation: relevance for human photocarcinogenesis. Photochem Photobiol 1996;63(4):394-396
Strickland FM, Pelley RP, Kripke ML: Prevention of ultraviolet radiation-induced suppression of contact and delayed hypersensitivity by Aloe barbadensis gel extract. J Invest Dermatol 1994;102(2):197-204

Carol Potera is a freelance medical writer in Great Falls, Montana.

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