We determined the skin permeation of rhododendrol (RD) after finite doses of layered application of RD-containing cosmeceutical products. It was believed that the layered application increased the skin permeation of RD, causing the development of white blotches and depigmentation in various parts of the face and the body. The present results, however, clearly indicated that the layered application of products decreased the skin permeation of RD, although the increase in application volume may be a reason for the high skin permeation of RD.

This study aims to establish spectral characteristics in order to develop Light Emitting Diode (LED) light sources which improve the appearance of facial skin color, the important visual target for us. We conducted a subjective experiment with a novel index of the preference of facial skin color “PS” under various Correlated Color Temperature (CCT) and Duv (the distance from the blackbody curve for the color temperature) conditions. The results show the best ranges of PS and Duv differ depending on CCT. It is also found that the key spectral component for preferred appearance of facial skin color is in the range between 570 and 580 nm.