• The photo-cytotoxic, -mutagenic, and -clastogenic properties in V79 cells of thirteen furocoumarins (FCs), were analyzed. • Nine FC mixtures including one mixture ‘representing’ FCs in Angelica archangelica extract were tested. • The concept of relative potency factors for photo-cytotoxicity, -mutagenicity, and -clastogenicity was applicable to all congeners. • The concept was applied successfully to binary mixtures of 5- and 8-methoxypsoralen and to complex FC mixtures.
