PHOTOMUTAGENESIS TEST DEVELOPMENT .1. 8-METHOXYPSORALEN, CHLORPROMAZINE AND SUNSCREEN COMPOUNDS IN BACTERIAL AND YEAST ASSAYS

Two in vitro genotoxicity tests have been adapted to the evaluation of photomutagenic activity of test compounds. The study was initiated to obtain an experimental basis relating to newly proposed guidelines of the EC which request the screening of UV-absorbing compounds, for exa mple, those employed in sunscreen preparations, for their photomutagen ic potential. The well established photomutagens 8-methoxypsoralen and chlorpromazine were used to define relevant test protocols. The compo unds were evaluated with the Ames test and the Saccharomyces cerevisia e D7 test for gene conversion. The influence of various parameters suc h as UV light sources, spectral composition, UV sensitivity of the tes t systems, absorbance by test materials and different exposure conditi ons is indicated. Two exemplary screening experiments with cosmetic in gredients are presented. Both test systems can be employed for the eva luation of compounds for photomutagenic activity although the standard excision-deficient strains of S. typhimurium pose problems because of their high UV sensitivity. The present experience in this complex fie ld suggests that rigid test protocols and a restrictive test battery w ould be inadequate.