Issue link: https://www.ascpskindeepdigital.com/i/70637
How Stable Is It? One of the most important factors in the effectiveness of a sunscreen formula is also one of the least known to the general public, and even to estheticians. Photostability is an ingredient's ability to remain effective after exposure to sunlight. Most estheticians are aware that this is an issue for numerous skin care ingredients, but may be surprised to learn that some active ingredients in sunscreen—a product whose sole purpose involves being exposed to sunlight—are not photostable. In addition, the FDA's new rules do not require sunscreen ingredients to be tested for photostability. Yet, many consumers expect that their sunscreen will protect them for longer than one hour. Physical filters such as zinc oxide and titanium dioxide are photostable. Studies have shown that these ingredients suffer no degradation after more than two hours of sun exposure.1 However, the chemical filter avobenzone is not at all photostable, and degrades almost completely in less than one hour.2 Even worse, avobenzone also degrades on contact with other UV filters such as zinc oxide or titanium dioxide, and with metal ions such as iron oxide, which is commonly found in makeup.3 This goes a long way toward explaining why many consumers experience sunburn even after applying sunscreen as directed. Health Concerns Effectiveness is not the only thing to consider in any product being applied to the face or body. Significant health concerns have also been raised about many sunscreen ingredients. The new rules do not address these concerns, and sunscreen manufacturers are not currently required to prove that their ingredients are safe. The FDA has stated, "We intend to address carcinogenicity and other safety considerations related to sunscreen active ingredients in a future rulemaking."4 In the meantime, here are some issues to consider. Significant health concerns have also been raised about many sunscreen ingredients. The new rules do not address these concerns. Considering all these factors, physical UV blockers represent the best choice overall. The main challenge in getting consumers to use sunscreens based on physical filters is purely cosmetic: zinc oxide and titanium dioxide tend to feel thick and greasy, and are visible on the skin, leaving a white residue. However, new advances mean there are now an increasing number of sunscreens that use these ingredients in formulations that allow for clear application. When evaluating a sunscreen, the most important considerations should be safety and effectiveness. Carefully examine the ingredients and make use of all available information to make the best choices for yourself, your family, and your clients. Avobenzone has been found to generate free radicals beyond acceptable safety levels after sitting on the skin for just one hour,5 women have been advised not to use products containing it.6 Octocrylene, which is known to act as an endocrine disrupter, is used in many sunscreens as a stabilizer. It can also cause skin irritation. According to the Archives of Dermatology, "Octocrylene appears to be a strong allergen leading to contact dermatitis in children and mostly photoallergic contact dermatitis in adults."7 Chemical UV filters can also have harmful effects on the environment. Octocrylene does not seem to be effectively contained in wastewater treatment plants, and studies in Switzerland have indicated that it accumulates in fish. Oxybenzone, a chemical UV-B filter often used in combination with avobenzone, has been found to negatively impact reef ecosystems and biodiversity.8 Physical UV filters, in contrast, have an excellent safety profile. The FDA has long considered zinc oxide to be a safe ingredient for both external use and as a food additive, even in infant formula. and children and pregnant NOTES 1. Environmental Working Group, "EWG's Methodology for Assessing Sunscreens," accessed April 2012, http://breakingnews.ewg. org/2011sunscreen/ewg-s-methodology-for- assessing-sunscreens/. 2. US Food and Drug Administration, Labeling and Effectiveness Testing: Sunscreen Drug Products for Over-the-Counter Human Use (Silver Spring, MD: Center for Drug Evaluation and Research, 2011): 35,653. 3. Uyen Nguyen and David Schlossman, "Stability Study of Avobenzone with Inorganic Sunscreens," accessed April 2012, http://www. koboproductsinc.com/Downloads/NYSCC- Avobenzone.pdf. 4. Labeling and Effectiveness Testing: 35,622. 5. K.M. Hanson, E. Gratton, and C.J. Bardeen, "Sunscreen Enhancement of UV-Induced Reactive Oxygen Species in the Skin," Free Radical Biology and Medicine, 41 (2006): 11,205–11,212. 6. C.G. Hayden, M.S. Roberts, and M.A. Benson, "Systemic Absorption of Sunscreen after Topical Application," Lancet 350 (1997): 863–864. 7. Martine Avenel-Audran et al., "Octocrylene, An Emerging Photoallergen," Archives of Dermatology 146 (2010): 753–757. 8. H.R. Buser et al., "Occurrence of UV Filters 4-Methylbenzylidene Camphor and Octocrylene in Fish from Various Swiss Rivers with Inputs from Wastewater Treatment Plants," Environmental Science & Technology 40 (2006): 1427–1431. Jason Barbaria is director of marketing at Dermagenics, a skin care line that includes sunscreen, cleansers, and moisturizers. Contact him at jb@dermagenics.com. Get connected to your peers @ www.skincareprofessionals.com 33