DOI: 10.1140/epjst/e2008-00490-8 THE EUROPEAN PHYSICAL JOURNAL SPECIAL TOPICS

Abstract. Although solar radiation is essential for maintenance of life in Earth, excessive exposition to the ultraviolet radiation emitted by the sun may cause sun-burns, early aging and even cancer lesions. Sunscreens act absorbing or reflecting ultraviolet radiation; in this way, they protect the skin against the damages caused by excessive absorption of ultraviolet radiation. Sunscreens must present photosta-bility, that is the capacity of a product to be retained in skin without degradation by light incidence. The present study aimed to evaluate, through photoacoustic spectroscopy (PAS) measurements, the photostability of a sunscreen commercially available in Brazil. PAS measurements were performed at 19Hz, for wavelengths between 270 nm and 400 nm, using a sunscreen with solar protection factor (SPF) 15 applied in skin samples. Photoacoustic spectra of the sunscreen applied to the skin were obtained and analyzed as a function of time after application. Photo-stability was then evaluated by the comparative study of the integrated areas of the absorption curves for the sunscreen applied to the skin. Results indicate that the sunscreen analyzed was photostable for a large period and was not completely removed by cleaning.