4-((5-((2,4-Dimethylphenyl)diazenyl)-3-((E)-(2,4-dimethylphenyl)diazenyl)-2,4-dihydroxyphenyl)diazenyl)benzenesulfonic Acid is a byproduct 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.