[First results of an EC/COLIPA validation project of in vitro phototoxicity testing methods]

In a joint project six laboratories from the European cosmetics industry (COLIPA) as well as from FRAME (England) and ZEBET (Germany) are validating in vitro methods to be incorporated into new international guidelines for photoirritancy testing. During the first stage of the study it was attempted to select the most promising in vitro photoirritancy tests for further validation. Twenty chemicals with known photoirritation properties (12 phototoxins (PT), 4 non-PTs and 4 UV absorbing non-PTs) were tested under identical UV exposure conditions (5 J/cm2, UV-A sun simulator) in a standardized cytotoxicty assay using 3T3 fibroblasts (endpoint): Neutral red uptake, NRU). The chemicals were also tested with in vitro phototoxicity assays established in industrial laboratories, e.g. the photohaemolyses (Pape et al, 1993), histine oxidation, candida albicans (Johnson et al, 1986), and, furthermore two commercial tests (SOLATEX PItrade mark and Skin2trade mark). Data from the 3T3 NRU photoirritancy test, the red blood cell photohaemolysis test and the Skin2trade mark assay showed a better overall correlation to human in vivo data than results from the other tests. These simple assays therefore, seem very promising for further validation under blind conditions. The protocols of the other tests have to be improved and standardized to permit better interlaboratory comparison.