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Sunburn protection as a function of sunscreen application thickness differs between high and low SPFs
Author(s) -
Liu Wei,
Wang Xuemin,
Lai Wei,
Yan Tian,
Wu Yanyu,
Wan Miaojian,
Yi Jinling,
Matsui Mary S.
Publication year - 2012
Publication title -
photodermatology, photoimmunology and photomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.736
H-Index - 60
eISSN - 1600-0781
pISSN - 0905-4383
DOI - 10.1111/j.1600-0781.2012.00650.x
Subject(s) - sunburn , sun protection factor , sun protection , sunscreening agents , toxicology , medicine , dermatology , biology , cancer , skin cancer
Summary Background Sunscreens are an important component of healthy sun‐protection behavior. To achieve satisfactory protection, sunscreens must be applied consistently, evenly and correctly. Consumers do not apply sunscreen properly and, therefore, do not achieve the protection indicated by the label ‘sun protection factor’ ( SPF ). The objective of the present study was to determine the actual sun(burn) protection given by a range of sunscreen application thickness levels for both low and high SPF formulas. Subjects and Methods Forty study subjects were recruited from each of three geographical regions in C hina. Sunscreens with label SPFs of 4, 15, 30, and 55 were tested at application levels of 0.5, 1.0, 1.5, and 2.0 mg/cm 2 in three laboratories using a standard SPF protocol. Results Sunscreens with lower SPFs (4 and 15) showed a linear dose–response relationship with application level, but higher SPF (30 and 55) product protection was exponentially related to application thickness. Conclusion Sunscreen protection is not related in one uniform way to the amount of product applied to human skin. Consumers may achieve an even lower than expected sunburn protection from high SPF products than from low SPF sunscreens.