title: Correlation of spectrophotometric data with sunscreen protection factors.
abstract: Synopsis Sunscreen protection factors, obtained for dilute solutions contained in 2 cm quartz cells placed between a human subject and the Xenon Are sun simulator lamp, are able to be correlated with spectrophotometric data. The correlation, interpreted in terms of the mechanism of sunscreen protection, successfully predicts that an opacifier which is active only in the UV-A spectral region, though ineffective as a sunscreen by itself, would significantly enhance the protective ability of an opacifier which is active mainly in the UV-B spectral region, and that complete erythemal prevention requires opacification to both the UV-B and UV-A regions. This correlation is reached by measuring the total area under the spectral curve in the UV-A and UV-B regions as predicted by a new form of Beer's law, for polychromatic radiation, which is derived. The procedure is shown to be a simple approach to predicting the efficacy of various sunscreen agents which do not exhibit fluorescence.
authors.affiliation: Avon Products, Inc., Suffern, NY 10901, U.S.A.
authors.forename: A J
authors.initials: AJ
authors.lastname: Petro