Epidemiologic studies have demonstrated that sunscreens do not always prevent skin photo-damages since several factors may affect their efficacy, such as sweating, rubbing, water immersion
and photodegradation [1,2].Thereforeteststhatsimulatethereal conditionsofsunscreenusearemandatory,notablyphoto-stability and water resistance measurements. In Europe, the official and internationally accepted method for sunscreen tests is the in vivo SPF method which is based on the COLIPA guidelines [3].The in vivo method is expensive and time consuming; therefore it would not be suitable for routinely quality control in the event that such tests are compulsory. In the last years, two main aspects of sunscreen tests have been investigated: refining a method to assess SPF by in vitro tests and standardizing a test procedure for UVA protection labelling. Recently COLIPA has published the guidelines for in vitro UVA protection determination [4]. A sunscreen in vitro test is based on absorbance (calculated from transmittance) or reflectance measurements. It requires the definition of both the instrumentation to be used and the measurement procedure including substrate selection and relative application criteria of the sunscreens. With regard to the instrumentation, the absorption spectrum is the most relevant parameter for defining the protective performance of a sunscreen
Epidemiologic studies have demonstrated that sunscreens do not always prevent skin photo-damages since several factors may affect their efficacy, such as sweating, rubbing, water immersion
and photodegradation [1,2].Thereforeteststhatsimulatethereal conditionsofsunscreenusearemandatory,notablyphoto-stability and water resistance measurements. In Europe, the official and internationally accepted method for sunscreen tests is the in vivo SPF method which is based on the COLIPA guidelines [3].The in vivo method is expensive and time consuming; therefore it would not be suitable for routinely quality control in the event that such tests are compulsory. In the last years, two main aspects of sunscreen tests have been investigated: refining a method to assess SPF by in vitro tests and standardizing a test procedure for UVA protection labelling. Recently COLIPA has published the guidelines for in vitro UVA protection determination [4]. A sunscreen in vitro test is based on absorbance (calculated from transmittance) or reflectance measurements. It requires the definition of both the instrumentation to be used and the measurement procedure including substrate selection and relative application criteria of the sunscreens. With regard to the instrumentation, the absorption spectrum is the most relevant parameter for defining the protective performance of a sunscreen
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