Skin Cancer xxix, 2011 : Page 58

HEALTH is FDA-approved for human use based on exhaustive review. The Skin Cancer Foundation’s Photobiology Committee reviewed the studies as well, finding no basis for concern about the use of sunscreens containing oxybenzone. RETINYL PALMITATE skin cancer risk. 19 Oral retinoids are often prescribed to help prevent skin cancers in people at high risk of the disease! 25,26 NANOPARTICLES UV Action Spectrum Maximum Concentration ACTIVE INGREDIENTS Chemical Filters UVA Filters Oxybenzone Sulisobenzone Dioxybenzone Avobenzone (Parsol 1789) Meradimate Ecamsule a (Mexoryl SX) 6% 10% 3% 3% 5% 10% 15% 8% 3% 7.5% 5% 15% 12% 10% 4% 25% 25% UVB, UVA II UVB, UVA II UVB, UVA II UVA I UVA II UVB, UVA UVB UVB UVB UVB UVB UVB UVB UVB, UVA II UVB UVB, UVA b UVB, UVA b Retinyl palmitate, a common sun-screen ingredient in trace amounts, is the form of vitamin A stored by the skin. Vitamin A is an essential nutrient, and the National Institutes of Health’s Office of Dietary Supple-ments recommends that adults obtain 3,000 to 4,300 International Units (IU) a day. 20 The safety of sunscreens has now been studied in labs and on live subjects by research scientists for years, and the evidence that sunscreens are safe and effective is overwhelming. Several studies suggest that when exposed to UV radiation, retinyl palmitate generates free radicals, 21,22 chemically reactive substances whose interactions with DNA may cause mutations leading to cancer. However, these studies have ex-amined retinyl palmitate only as it reacts to UV radiation in isolation. In practice, when a sunscreen with retinyl palmitate is applied to the skin, antioxidants like vitamins C and E present in the body can neutralize free radicals. 23 Bottom line: There is no scientific evidence that retinyl palmitate causes cancer in humans. The research that generated the controversy is an un-published 10-year-old study in mice, 24 far from proof of anything in humans. In fact, retinoids (topical vitamin A products similar to retinyl palmitate) are commonly prescribed by der-matologists, and no published data suggests that topical retinoids increase 58 Titanium dioxide and zinc oxide are physical sunscreens with a long history of use, and considered two of the most protective broad-spectrum ingredients. They are comprised of large particles which, in traditional sunscreen formulations, showed up on the skin as a thick, white paste. By minimizing, or “micronizing,” the size of sunscreen particles, the ingredients’ characteristic opacity is reduced, giving the skin a much more natural appearance. As nanoparticles (a nanometer is one billionth of a me-ter; nanoparticles are from 1 to 100 nanometers), zinc oxide and titanium dioxide offer the ingredients’ sun pro-tection abilities with a more appealing cosmetic appearance. The concern is that nanoparticles can be absorbed by the skin and harm living skin tissue. However, current research indicates that fears about ab-sorption are unwarranted: Sunscreen is applied to the stratum corneum, the outermost layer of skin, which is made up of dead cells, and multiple studies have shown that nanoparticles do not penetrate living skin. 27,28,29,30,31,32 Additionally, in sunscreen formulas, it appears that nanoparticles tend to clump together to form larger-than-nano-sized particles. The safety of sunscreens has now been studied in labs and on live sub-jects by research scientists for years, and the evidence that sunscreens are safe and effective is overwhelming. We urge you to protect yourself from the sun using all the basic sun protection strategies — including shade, long clothing, UV-blocking sunglasses, wide-brimmed hats, and sunscreen. References available on p.97. DR. MORISON is Professor of Dermatology, Johns Hopkins University at Green Spring Station, Lutherville, MD, and chairman of The Skin Cancer Foundation’s Photobiology Committee. Dr. Morison has published more than 130 original papers in journals and is an author of two textbooks and over 30 chapters. UVB Filters PABA Padimate-O Cinoxate Octinoxate Octisalate Homosalate Trolamine salicylate Octocrylene Ensulizole Physical Filters Titanium dioxide Zinc oxide a b Only as a component of certain approved sunscreen formulations approved under the new drug application. Absorption varies depending on the particle size. As over-the-counter (OTC) drugs, sunscreen ingredients must be approved by the US Food and Drug Administration (FDA) prior to release for sale in the US. Currently 17 sunscreen ingredients are approved, including oxybenzone, titanium dioxide, and zinc oxide. In addition, several ingredients are under FDA consideration: Tinosorb ® M (bisoctrizole); Tinosorb ® S (bemotriz-inol); octyl triazome; amiloxate; enzacamene, and isotrizinal. He directs training courses in photomedicine and has been an invited speaker at many national and international meetings in his specialty. DR. WANG is Director of Dermatologic Surgery and Dermatology, Memorial Sloan-Kettering Cancer Center at Basking Ridge, NJ. A member of The Skin Cancer Foundation’s Photobiol-ogy Committee and the International Affairs Committee of the American Academy of Dermatology, he specializes in the diagnosis, treatment, and prevention of skin cancers, especially melanoma. Dr. Wang is actively involved in clinical research, with a focus on photoprotection and the development of non-invasive imaging technologies to diagnose skin cancer. He has authored more than 50 publi-cations in peer-reviewed scientific journals and academic textbooks. He is also the author of the book Beating Melanoma—A Five-Step Survival Guide , published by Johns Hopkins University Press. S K I N CA N C E R F O UND A T I O N J O URN A L

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