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Sun Protection: What We and Our Patients Need to Know To preserve their health and the appearance of their skin, patients need straight- forward, practical advice on susncreen selection and protection strategies.

By Jonathan Wolfe, MD

rom preventing skin cancer to pre- measures protection against cutaneous burning. Even a FDA public education serving a youthful appearance, burning—the effects of UVB—and does piece states, “A higher number means it Fsunscreens play an important role not account for UVA radiation at all.5 As protects longer.”7 This is not a strictly in dermatologic care. However, some a result, a product with a high SPF could accurate interpretation of the SPF value confusion persists among patients and actually confer little or no protection and ignores the fact that unique proper- even some practitioners when it comes to against UVA. ties of the main ingredients SPF, available chemical and physical sun- The somewhat esoteric description of (chemical or physical) and the formula- screens, and the best advice for sun SPF calculation is available online at the tion (waterproof, water resistant) influ- avoidance. In recognition of the AAD’s FDA website.6 Ultimately, the SPF num- ence duration of protection. Skin Cancer Detection and Prevention ber represents the ratio of the MED for Patients also often falsely assume that Month, I’ll review important patient protected skin (MED(PS)) to the MED the increase in SPF value is proportion- education points. for unprotected skin (MED(US)). Tests ate to the increase in UVB protection. It are conducted only in patients with skin is not. A product with SPF 30 does not Understanding SPF types I-III, and the applied MED(PS) block twice the amount of UVB as a The non-scientific explanation of radia- ranges from 0.64 to 1.56 times the product with SPF 15. In actuality, an tion is that UVA contributes significantly MED(US) depending on skin type. SPF 30 product may filter out less than to aging while UVB is responsible for A common belief among patients is 97 percent of UVB, while SPF 15 may burns. Scientific evidence supports these that the SPF number reflects a time fac- filter out more than 93 percent. observations but shows the reality is far tor—the higher the number the more Because SPF value only addresses the more complex. UVB levels, which are time one can spend outdoors without UVB protection a product confers, der- relatively low compared to UVA, pene- trate the superficial epidermal layers, UV-C UV-B UV-A where the absorbed energy produces ery- thema and can induce cellular damage Aminobenzoic acid (PABA) that may lead to skin cancer formation.1,2 UVA radiation penetrates more deeply, through most and into the epi- dermis and dermis. UVA has long been MenthylAnthranilate 4 associated with risk (the (Parsol 1789) mechanism remains unclear), and recent research suggests that it also plays a role Octylmethoxycinnamate in the development of squamous cell and basal call carcinomas.3 In addition to causing direct damage to cells, UVA radi- ation is linked to free-radical generation.

While both UVA and UVB radiation Table 1. UV Absorption Spectrum Phenylbenzimidazole sulfonic acid are associated with skin cancer risk, the sun protection factor or SPF scale used to rate sunscreen formulations only Adapted from www.solumedia.com/sunscreen3.htm Wavelength in nm 200 220 240 260 280 300 320 340 360 380 400

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matologists now recommend that chemical for UVB protection. Table 1 over the Internet. An Australian study is patients look for and use only “broad- lists UV protective absorption spectrums underway to assess the benefit of such spectrum” sunscreen products. To help of most approved sunscreen ingredients. clothing. There is even a laundry additive patients make wise product choices, we Some confusion exists regarding water (Sun Guard) that increases the UV must explain SPF to them and offer resistance of sunscreen products. The blocking ability of clothes. Some beach some advice on identifying and choosing label SPF of a “water resistant” product is may permit a fair amount of the most effective ingredients. the SPF calculated after application and UVR to pass through. Patients can pur- subsequent exposure to water for 40 chase umbrellas and canopies made from Physical and Chemical Blocks minutes. The label SPF of a “very water UVR-reflecting materials. The ingredient with the widest protec- resistant” product is the SPF after 80 Finally, when asking patients to aban- tive absorption spectrum available in the minutes. Note that in both assays, sub- don a bad habit, such as tanning, it helps US is micronized zinc oxide (ZnO) or Z- jects air dry after emerging from the to offer alternatives. UV-free tanning Cote, which offers absorption from water but before enduring UV irradia- with DHA sprays and lotions is a safe about 250nm to 400nm. As a physical tion; they do not towel off. In reality, alternative that may be worth consider- sunscreen, ZnO sits on the skin to create patients who towel off theoretically ing.9 A recent study revealed that college a reflective barrier against UVR, whereas remove at least some sunscreen product. students who received education about chemical absorb into the skin. photoaging, UV photographs, and access At concentrations of 3.5% or more, Beyond Sunscreens to sunless tanning engaged in greater sun micronized ZnO confers good broad- Beyond helping patients decide which protection behaviors than controls or spectrum protection. Nonetheless, it is sunscreens to use, offer directions on those who received education and pho- often formulated with other physical and how to properly use it. Stress the need tography alone.10 chemical sunscreens to enhance protec- to apply sunscreen 15 minutes before tion. Zinc oxide is very water resistant. exposure to and the need to A Skin Wellness Program Like zinc oxide, titanium dioxide apply it to all sun exposed skin. Depending on your particular patient (TiO2) is also a broad-spectrum physical Patients easily forget the hands, ears, base or practice focus, you may sunscreen, but its absorption spectrum back of the neck, and the feet. Esti- encounter individuals who are as inter- (260-360nm) does not extend as far into mates suggest that patients generally ested in reversing already apparent the UVA range. Even as a microfine par- apply about one third the recommend- photo-damage as they are in preventing ticle, TiO2 may produce a whitish ed amount of sunscreen to their skin additional injury. Be receptive to residue when applied to the skin. (2mg/cm2 of skin surface area). patients’ skin care concerns when dis- Parsol 1789 or avobenzone is another As we continue to stress sunscreen cussing sunscreens. popular sunscreen ingredient. This use, we must also offer patients practical For patients with mild to moderate chemical sunscreen absorbs across the advice about sun avoidance and sun-pro- photodamage, topical retinoids are an full UVA spectrum but confers no UVB tection tactics. Patients should avoid obvious choice for inclusion in the regu- protection. It must be combined with direct sunlight as much as possible, espe- lar skincare regimen. Beyond their role in UVB blocking ingredients to confer full- cially during midday, and should not use diminishing fine lines and wrinkles and spectrum UVR protection. There’s con- UV tanning lamps and beds. There’s a evening skin tone, topical retinoids influ- troversy regarding the photostability of persistent myth, promulgated to some ence cell differentiation and can block avobenzone with some reports (but no extent by the tanning salon industry, that proliferation of malignant cells. accessible published studies) suggesting a “base tan” can be protective. Tell For patients with very mild signs of that the agent degrades upon exposure to patients this is false. photodamage, a cosmeceutical product UVR. A 1996 study in Journal of Apparel, including broad-brimmed may be appropriate based on your assess- Chromatography BioMedical Applications hats and scarves, can be protective, but ment of the product and its efficacy. reportedly showed that the concentration patients may not realize that UVR, par- Note that there’s continuing research of avobenzone in a sample decreased by ticularly UVA, can penetrate many fab- into the incorporation of topical antioxi- just 25 percent following 72 hours of rics, particularly cotton weaves and wet dants within sunscreens to offer protec- sun exposure. clothing. Specially-woven and treated tion and reversal of oxidative stress. Oxybenzone is another UVA screen, fabrics that reflect both UVA and UVB However, there’s no evidence that any though its absorption range is relatively radiation are used to make , available product formulated with narrow. is every-day clothing, and hats. Many antioxidants confers additional benefit probably the most commonly used brands and styles are available, many over standard sunscreens.

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Oct;15(5):316-20. 6. Code of Federal Regulations, Title 21, Volume 5, Assume Nothing 2. van Weelden H, van der Putte SC, Toonstra J, van der Revised as of April 1, 2004. To help patients protect themselves from Leun JC. B-induced tumors in pigmented hair- 7. http://www.fda.gov/opacom/lowlit/sunsafty.html less mice, with an unsuccessful attempt to induce cuta- 8. www.cosmeticscop.com skin cancer, we must offer clear advice neous melanoma. Photodermatol Photoimmunol Photomed. 1990 Apr;7(2):68-72. 9. Levy SB. Tanning preparations. Dermatol Clin. 2000 on sunscreen selection, stress the need for Oct; 18(4):591-6. 3. Agar NS, et al. The basal layer in human squamous sun avoidance and use of physical skin tumors harbors more UVA than UVB fingerprint muta- 10. Mahler HI, et al. Effects of UV photographs, pho- tions: a role for UVA in human skin carcinogenesis. Proc toaging information, and use of sunless tanning lotion protection, and be prepared to help them Natl Acad Sci U S A. 2004 Apr 6;101(14):4954-9. on sun protection behaviors. Arch Dermatol. 2005 reverse damage already done. The patient Epub 2004 Mar 23. Mar;141(3):373-80. hand-out below summarizes key patient 4. Wang SQ, et al. Ultraviolet A and melanoma: a 11. Levy SB. Sunscreens and . review. J Am Acad Dermatol. 2001 May;44(5):837- Emedicine.com, November 25, 2002. education tips. Make copies and share 46. Review. 12. Harrison SL, Buettner PG, Maclennan R. The North them with your patients. 5. Poon TS, Barnetson RS, Halliday GM. Prevention of Queensland "Sun-Safe Clothing" study: design and immunosuppression by sunscreens in humans is unrelated baseline results of a randomized trial to determine the to protection from erythema and dependent on protection effectiveness of sun-protective clothing in preventing 1. de Gruijl FR. Photocarcinogenesis: UVA vs. UVB radi- from ultraviolet A in the face of constant ultraviolet B pro- melanocytic nevi. Am J Epidemiol. 2005 Mar ation. Skin Pharmacol Appl Skin Physiol. 2002 Sep- tection. J Invest Dermatol. 2003 Jul;121(1):184-90. 15;161(6):536-45. Sun Safety Questions and Answers for Patients

What is Ultraviolet Radiation? What is SPF? Is Indoor Tanning Safe? Ultraviolet radiation (UVR) is light energy from SPF stands for sun protection factor, but it’s better What About a “Base Tan”? the sun that is invisible to the unaided human eye. to think of it as protection factor. It meas- Indoor tanning lamps and beds emit UVR identical It comes in three forms: UVA, UVB, and UVC. The ures protection against UVB but not UVA; a product to the energy from the sun, and it’s dangerous. ozone layer blocks most UVC and much of the UVB with a high SPF may not offer good protection Indoor tanning can cause skin aging and cancer energy from the sun. Of the three, UVA is most against UVA, which also damages the skin. over time. There is no evidence that a “base tan” abundant at ground level. The higher the SPF number, the greater the protec- offers any short- or long-term protection. tion against UVB. SPF values range from 2 (inade- “Sunless tanning” with either spray-on tanners or How Does UVR Affect Our Skin? quate protection) to 45. A product with SPF 30 at-home creams and lotions is safe and non-toxic. UVB energy affects the outermost layers of the offers more protection than SPF 15, but it does not Note that the main ingredient (DHA) colors the skin (epidermis) and can cause . It can offer double protection. The SPF system will soon skin but does not protect it from UVR. You still also cause cell damage that over time leads to for- change to a more useful system. need to use sunscreen. mation of certain types of skin cancer. UVA penetrates into deeper levels of skin (dermis). What SPF Should I Use? What Else Should I Do? Over time damage can produce signs of aging Always look for products with a SPF of at least 15 Avoid direct sunlight during midday (10 am to 4 (wrinkling and blotchy skin) as well as certain that offer “broad spectrum” protection. Broad spec- pm). If you are going to spend time in the sun, in types of skin cancer, such as melanoma. trum means the sunscreen blocks UVB (measured addition to sunscreen wear a broad-brimmed hat by SPF) and UVA. Any broad spectrum product will and cover as much of your skin as you can. If pos- Can We Avoid UVR? include either avobenzone (Parsol 1789), zinc sible, wear long sleeves and pants. Some clothes UVR is everywhere around us, and there are even oxide, or titanium dioxide. Ask your doctor which offer more protection than others. Certain compa- detectable levels at night. Physical objects (trees, ingredients he or she thinks you should look for. nies sell UV-blocking clothing. There are also laun- walls, some clothing, etc.) can block UV radiation. dry rinses that add protection to clothes. For infor- The best way to avoid dangerous levels of UVR is How Do I Use Sunscreens? mation about these, ask your doctor. At the beach to avoid direct sunlight. Apply your sunscreen at least 15 minutes before or when camping, use UV-proof beach umbrellas, heading outside. You should apply a broad spec- canopies, and tents for protection. What About Sunscreens? trum sunscreen to sun-exposed skin every day. Sunscreens help protect the skin from UVR. Some When you know you’ll be outdoors, be sure to re- Is it Too Late to Correct Old Damage? sunscreen ingredients are called “physical sun- apply sunscreen according to the product direc- Depending on the extent of the damage, there are screens.” These include zinc oxide and titanium tions. Even if a product is waterproof or sweat- medical and cosmetic treatments that can help dioxide. These molecules “sit” on the skin and proof, you should re-apply it regularly for maxi- restore the health and appearance of your skin. reflect UVR away. mum protection. You need about one ounce of There are effective treatments for skin cancer, but “Chemical sunscreen” ingredients, like avobenzone sunscreen to adequately cover your body, plus early detection is important. See your dermatolo- (Parsol 1789) and oxybenzone, absorb UVR some more for your face and head. Don’t forget gist for regular skin exams and always seek med- before it affects the skin. Some ingredients block to apply sunscreen to your hands, ears, back of ical attention for new or changing moles, freckles,

UVA and UVB. Some only block UVA or UVB. your neck, exposed scalp, and feet. and “spots” on your skin. Photocopy and distribute this patient education page or download copies at www.practicaldermatology.com in the May content.

58 Practical Dermatology May 2005