2,4-Dihydroxy-5-((4-sulfophenyl)diazenyl)benzoic Acid is an intermediate in the synthesis of Acid Orange 24 (A189835), which is used in trickling biofilters for wastewater treatment. Acid Orange 24 is used in suncare compositions. It also serves as a raw material for cosmetics. Mutagenicity test for dye compositions in cosmetics.