A by-product of the destructive distillation of coal used as a topical antieczematic. It is an antipruritic and keratoplastic agent used also in the treatment of psoriasis and other skin conditions. occupational exposure to soots, tars, and certain mineral oils is known to be carcinogenic according to the Fourth Annual Report on carcinogens (NTP 85-002, 1985) (Merck Index, 11th ed).