Bithional is generally added to the soaps as an additive to function as a/an:

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Bithionol is generally added to the soaps as an additive to function as an antiseptic. It reduces the odour produced by bacterial decomposition of organic matter on the skin. Bithional is an aromatic compound which contains sulphur and is used in soaps. Its IUPAC name is 2 , 4 -dichloro- 6 -( 3 , 5 -dichloro- 2 -hydroxyphenyl)sulfanylphenol.