Coal tar

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Coal tar is the liquid by-product of the distillation of coal to make coke. The gaseous by-product produced by this process is commonly known as town gas. See also preservative and creosote.

Coal tar is a brown or black liquid of high viscosity, which smells of naphthalene and aromatic hydrocarbons. Being flammable, it is sometimes used for heating or to fire boilers. Like most oils, it must be heated before it will flow easily.

It can be made into coal tar soap, and is used in medicated shampoo to kill and repel head lice and as a treatment for dandruff and psoriasis. When used as a medication in the U.S., coal tar preparations are considered an OTC (over-the-counter drug) pharmaceutical and are subject to regulation by the United States Food and Drug Administration.

According to the International Agency for Research on Cancer, coal tar is a Group 1 carcinogen.

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