{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T20:30:25Z","timestamp":1791232225432,"version":"4.1.0"},"reference-count":27,"publisher":"Wiley","issue":"S1","license":[{"start":{"date-parts":[[2025,7,10]],"date-time":"2025-07-10T00:00:00Z","timestamp":1752105600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Intern J of Cosmetic Sci"],"published-print":{"date-parts":[[2025,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>Determination of the sunburn protection provided by a sunscreen product is required globally for sales of these products. Over the past 80\u2009years, many aspects of determining the protection \u2018factor\u2019 have evolved and been modified, with varying levels of impact on the sunburn protection factor (SPF) value. In order to compare new non\u2010invasive and in\u00a0vitro methods against traditional SPF test protocols, a large, multi\u2010center clinical trial was conducted to establish the level of equivalence of these new methods with the current codified testing standard ISO24444 ([1]: Cosmetics \u2013 sun protection methods \u2013 in\u00a0vivo determination of the sun protection factor (SPF), 2019). This report reports the variability found in the in\u00a0vivo determination of SPF values.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Thirty\u2010two products of varying levels of sunburn and UVA protection, in a variety of formulation vehicles and ultraviolet (UV) filter combinations and concentrations, were coded and sent to pre\u2010qualified in\u00a0vivo SPF testing laboratories. The products were divided into eight product groups (four products per product group). For each product group, samples were sent to four laboratories (across product groups, a total of 12 laboratories participated). Precision and trueness estimates were calculated separately for each product group. \u2018Expected\u2019 SPF values were not provided to the test laboratories. However, laboratories were informed as to whether the \u2018true\u2019 SPF was less than or greater than 25.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Interlaboratory variability for samples was proportional to the SPF of the products, with high SPF products having higher variability. Intra\u2010laboratory variability (repeatability) was much lower than the interlaboratory variability.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>This study highlights the fact that the interlaboratory variability of SPF results is considerable and is likely greater than expected by the public and regulatory bodies.<\/jats:p><\/jats:sec>","DOI":"10.1111\/ics.70000","type":"journal-article","created":{"date-parts":[[2025,7,10]],"date-time":"2025-07-10T10:13:31Z","timestamp":1752142411000},"page":"25-36","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["The variability of in\u00a0vivo sunscreen sun protection factor values"],"prefix":"10.1111","volume":"47","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2519-3198","authenticated-orcid":false,"given":"Curtis","family":"Cole","sequence":"first","affiliation":[{"name":"Sun &amp; Skin Consulting LLC, New Holland  New Holland Pennsylvania USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4743-1150","authenticated-orcid":false,"given":"Bertrand","family":"Colson","sequence":"additional","affiliation":[{"name":"QuoData GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steffen","family":"Uhlig","sequence":"additional","affiliation":[{"name":"QuoData GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,7,10]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2133.2001.04016.x"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2133.1999.02658.x"},{"key":"e_1_2_8_4_1","first-page":"242","article-title":"Sunbathers\u2019 application of sunscreen is probably inadequate to obtain the sun protection factor assigned to the preparation","volume":"9","author":"Bech\u2010Thomsen N","year":"1992","journal-title":"Photodermatol Photoimmunol Photomed"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1473-2130.2004.00107.x"},{"key":"e_1_2_8_6_1","first-page":"118","article-title":"Evaluation of protection against sunburn","volume":"146","author":"Blum H","year":"1945","journal-title":"Phys Rep"},{"key":"e_1_2_8_7_1","first-page":"166","article-title":"Sunscreen drug products for over\u2010the\u2010counter human use","volume":"43","author":"US\u2010FDA Sunscreen Monograph","year":"1978","journal-title":"Fed Regist"},{"issue":"98","key":"e_1_2_8_8_1","first-page":"1978","article-title":"Sunscreen drug products for over\u2010the\u2010counter human use","volume":"64","author":"FDA\u2010 Sunscreen Monograph","year":"1993","journal-title":"Fed Regist"},{"key":"e_1_2_8_9_1","unstructured":"Deutches Institut f\u00fcr Normung.Experimentelle dermatologische Bewertung des Erythemschutzes von externen Sonnenschutzmitteln f\u00fcr die menschliche Haut. 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