About the Authors Dominique Moyal, PhD. Dominique Moyal joined L’Oréal in 1984 after complet- ing a PhD in pharmaceutical sciences. She has spent most of her career within the research laboratories where she was responsible for the evaluation of effi cacy of sun care products. From 2007 to 2014, she was regulatory affairs manager in the photo- protection fi eld. From 2015 to 2018, she was deputy scientifi c director of La Roche- Posay Dermatological laboratories. Since 2019, she is scientifi c consultant for La Roche-Posay. Thierry Passeron, MD, PhD. Thierry Passeron is Professor and chair of Dermatology in the University hospital of Nice. He also heads the laboratory INSERM U1065 team 12, C3M, dedicated to the study of molecular mechanisms involved in pig- mentation and melanoma. He heads the University laser center in Nice. He is pres- ident of the Department of Clinical Research and Innovation of Nice University hospital. He has 9 international patents and more than 240 publications in scientifi c journals (h-index 44). He is co-founder of YUKIN therapeutics. His fi elds of re- search include pigmentary disorders (including vitiligo and melasma), melanoma, hidradenitis suppurativa, alopecia areata and lasers. Martin Josso, PhD. Martin Josso, after studying organic chemistry and obtaining a PhD from Wayne State University, joined L’Oréal in 1995. For the next 25 years, he has dedicated his career to the fi eld of photoprotection, formulating sunscreen products for the various L’Oréal brands worldwide. Since 2019, he is senior project leader in the Photoprotection Application domain, in charge of new UV fi ltration technologi- cal platforms. Stéphane Douezan, PhD. Stephane Douezan has studied soft matter sciences and formulation and joined L’Oréal in 2012 after completing a PhD in physical chemis- try. For 10 years, he has explored formulation and science of emulsions dedicated to skin application within the research laboratories. Since 2016, his activity is dedi- cated to the formulation of photoprotection products, and in 2019, he became head of the sun care development laboratory. Véronique Delvigne, holding a doctorate in pharmacy, specialized in skin biology, became scientifi c director of La Roche Posay in 2020. She joined the L’Oréal group in 1986 as a biophysics researcher, then moved to the laboratories business coordina- tion for 5 years, running development projects for the skin care, sun care, makeup, and fragrances metiers for the Active Cosmetics Division in Lancôme. In 1994, Véronique was appointed Head of Anti-Ageing and Whitening in Lancôme skin- care. In 2000, she created the Lancôme International Scientifi c Department, where she rolled out genomics, proteomics, stem cells, and microbiome studies. Véronique has been Lancôme’s scientifi c spokesperson for 20 years. Sophie Seité, PhD, studied biochemistry and molecular biology and obtained a PhD in 1989. For 20 years, she studied the clinical, biophysical, and histological effects of acute and repetitive exposure to UV radiation. In 2005, she joined La Roche- Posay Dermatological Laboratories, and for 6 years, she managed the clinical studies performed internationally with products dedicated to dermatologists. From 2011 to 2019, she was the international scientifi c director of this brand. She published more than 90 articles in international scientifi c journals and participated in global derma- tological, pharmaceutical, and biological congresses as speaker in numerous symposia.

J. Cosmet. Sci., 71, 199–206 (July/August 2020) 199 Formulation of Sunscreens for Optimal Effi cacy DOMINIQUE MOYAL, THIERRY PASSERON, MARTIN JOSSO, STÉPHANE DOUEZAN, VÉRONIQUE DELVIGNE, and SOPHIE SEITÉ, La Roche-Posay Dermatological Laboratories, 92300 Levallois-Perret, France (D .M., V.D., S.S.), Department of Dermatology, Université Côte d’Azur, CHU Nice, 06000 Nice, France and Université Côte d’Azur, INSERM, U1065, C3M, 06000 Nice, France (T.P.) , L’Oreal Research and Innovation, 94550 Chevil ly Larue, France (M.J., S.D.) Synops i s Skin ex posure to solar radiation can cause many adverse effects. In addition to the sun protection factor (SPF), a parameter associated with Ultraviolet B (UVB) protection, signifi cant evidence emphasized the crucial importance of a well-balanced protection against ultraviolet A (UVA) and for some indications, against high-energy visible light. Synergy between UV fi lters and fi lter photostability together with fi lm-forming ingredients such as polymers that ensure the homogeneous distribution of UV fi lters on the skin are key factors to avoid UVA– and UVB– provoked detrimental effects of solar radiation. Clinical studies mimicking real conditions of use have been performed. The results show that a well-balanced sunscreen with at least an SPF-to-UVA protection factor ratio 3 provides the most effective protection against DNA damage, skin photoimmunosuppression, photodermatoses, and pigmentation disorders. In addition, cosmetically pleasant sunscreens allow a suffi cient amount to be applied and re-applied by consumers, ensuring continuous and even coverage of the exposed skin. INTRODU CTION Ultravi olet B (UVB) (290–320 nm) radiation accounts for 5% of total solar Ultraviolet (UV) radiation. It causes adverse effects, such as sunburn and long-term damage includ- ing skin cancer, principally melanoma and squamous cell carcinoma (1,2), by directly impacting cellular DNA (3). Irrespe ctive of the meteorological conditions, ultraviolet A (UVA) (320–400 nm) irradi- ance is at least 17 times higher than UVB irradiance (4). UVA penetrates deeper into the skin than UVB. Via photosensitization processes, it produces reactive oxygen species that damage DNA, cells, vessels, and elastic fi bers in connective tissues, leading to photoag- ing (5–8). Within the UVA band, long UVA or UVA1 rays cause the most damage (9). UVA and B are implicated in immune system depression (10,11). Photosensitivity and pho- todermatoses are mainly UVA-induced (12), and UVA is a key factor in the aggravation of pigmentation through melanin oxidation and distribution (13,14). The sun protection Address all correspondence to Sophie Seité at sophie.seite@loreal.com.