Assessment of in vitro Sun Protection Factor (SPF) and rheological profile of commercial infant sunscreens

Fernanda Daud Sarruf; Daniela D’Almeida Peres; Deborah Oliveira Nishikawa; Vladi Olga Consiglieri; Telma Mary  Kaneko; Maria Valéria Robles Velasco; André Rolim Baby

Fernanda Daud Sarruf
Daniela D’Almeida Peres
Deborah Oliveira Nishikawa
Vladi Olga Consiglieri
Telma Mary Kaneko
Maria Valéria Robles Velasco
André Rolim Baby

Keywords: Sunscreen. In vitro SPF. Rheology. Spectral transmittance. Spectroscopy. UV radiation

Abstract

This research focused on the measurement of spectral transmittance using an integrating sphere to estimate the Sun Protection Factor (SPF) of commercial sunscreens oriented for child use. Commercially available SPF 30 sunscreens (A, B and C) were selected and assessed by the following methodology: pH measurement; rheological profile analysis; and in vitro SPF estimation by spectroscopy. Samples A, B and C exhibited, respectively, pH values of 7.8, 7.4 and 7.0. The rheological profile identified the systems as pseudoplastic nonNewtonian semisolids with hysteresis loops. The t-test (p < 0.05) was used to confront the claimed SPF (SPF = 30) with that estimated by spectroscopy. In vitro tests are considered of utmost importance in the cosmetic field, since their results may be used to validate submission to subsequent in vivo efficacy experiments. According to our results, sunscreens A, B and C generated SPF values without any significant difference from those claimed on the commercial sunscreen labels. The measurement of spectral transmittance with an integrating sphere proved to be a convenient, fast and reproducible method for SPF estimation.