title: Sunscreen application by photosensitive patients is inadequate for protection.
abstract: Photosensitive patients often comment that sunscreen products seem of little benefit. We used fluorescence spectroscopy to assess quantitatively their sunscreen application technique. A dose-response relationship for sunscreen skin surface thickness and fluorescence intensity was determined for an intrinsically fluorescent sunscreen, Neutrogena sun protection factor (SPF) 15. Ten women with long-standing photosensitivity conditions were asked to apply this sunscreen in the manner they would normally on a bright sunny day. Fluorescence measurements were taken from all unclothed body areas, comprising 17 sites of the head, neck, upper and lower limbs. Geometric regression analysis of the dose-response data showed a high level of correlation (r = 0.99) between sunscreen thickness and fluorescence intensity, allowing fluorescence measurements to be converted to an equivalent sunscreen thickness. The overall median sunscreen thickness was 0.5 mg/cm2, with median thicknesses of individual sites ranging from 0 to 1.2 mg/cm2. The most frequently missed sites were the posterior neck, lateral neck, temples and ears, all of which had median thicknesses of 0 mg/cm2. Hence, photosensitive patients fail to apply sunscreen in some prominently exposed sites, and use average thicknesses far less than the manufacturers' recommendation (2 mg/cm2). The level of protection is much lower than anticipated from the stated SPF of the product.
authors.affiliation: Photobiology Unit, Department of Dermatology, Royal Liverpool University Hospital, Liverpool L7 8XP, U.K.
authors.forename: R M
authors.initials: RM
authors.lastname: Azurdia
authors.forename: J A
authors.initials: JA
authors.lastname: Pagliaro
authors.forename: B L
authors.initials: BL
authors.lastname: Diffey
authors.forename: L E
authors.initials: LE
authors.lastname: Rhodes
mesh_terms: D000328:Adult; D000368:Aged; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008875:Middle Aged; D010349:Patient Compliance; D010787:Photosensitivity Disorders / Q000517:prevention & control*; D012646:Self Administration; D013050:Spectrometry, Fluorescence; D013473:Sunscreening Agents / Q000008:administration & dosage* / Q000627:therapeutic use
chemical_list: D013473:Sunscreening Agents