Coal tar can be injurious to health. Coal tar is also used to manufacture paints, synthetic dyes (notably tartrazine/Yellow #5), and photographic materials. In the coal gas era, there were many companies in Britain whose business was to distill coal tar to separate the higher-value fractions, such as naphtha, creosote and pitch. A great many industrial chemicals were first isolated from coal tar during this time. These companies included: Side effects of coal tar products include skin irritation, sun sensitivity, allergic reactions, and skin discoloration. It is unclear if use during pregnancy is safe for the baby and use during breastfeeding is
Coal tar skin can repair itself after short-term exposure to PAHs, but not after long-term exposure. Coal tar was one of the first chemical substances proven to cause cancer from occupational exposure, during research in 1775 on the cause of chimney sweeps' carcinoma. Modern studies have shown that working with coal tar pitch, such as during the paving of roads or when working on roofs, increases the risk of cancer. Coal tar contains many polycyclic aromatic hydrocarbons, and it is believed that their metabolites bind to DNA, damaging it. Long-term skin exposure to these compounds can produce "tar warts", which can progress