Patch testing with serial dilutions and thin-layer chromatograms of oak moss absolutes containing high and low levels of atranol and chloroatranol.
Oak moss absolute (Evernia prunastri extract) contains a large number of substances, among them the potent allergens atranol and chloroatranol. Since 2008, their content in oak moss absolute has been restricted by the International Fragrance Association to a maximum level of 100 ppm each.