It means that compounds derived from coal tar are used in the production process. Coal tar is produced by the destructive distillation of coal under very high temperatures. It may then be refined to produce Liquor Carbonis Detergens (LCD). Coal tar is also processed into many other products, such as lamp-black, for example, which is used to produce black dyes and inks. Coal tar is a complex hydrocarbon with numerous chemical constituents, such as benzene, toluene, zylene, phenol, cresol, napthaline, anthracine, and pitch. The composition depends on the source of the coal supply and variables in the distillation process. The health and safety issues related to these compounds have the highest impact on the industrial workers who are involved in manufacturing and handling coal tar. Coal tar ointments are used to treat psoriasis, eczema, seborrhea, and other skin conditions. Coal tar and LCD are used in many gels, creams, lotions, and shampoos, including antisepctic ointments. Coal tar and its derivatives can be painted on surfaces to protect them from corrosion. In spite of its grim name and although it is a dark-coloured industrial gunk, coal tar can be broken down and compounded to form many useful chemical products. Labelling something as containing "coal tar derivatives" does not mean it contains coal tar itself, only that compounds derived from it were used in the manufacturing process or are incorporated into the final product. Coal tar is just one more hydrocarbon that thousands of products are derived from.