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
Cedar oil was laid in natrum or natron—a fixed alkali—for the prescribed period, after which the cedarwood oil, which had dissolved the soft organs, was released; and the body, its flesh dissolved by the natron, was reduced to preserved skin and bones. Until the development of synthetic immersion oil in the 1940s, cedarwood oil was widely used for the oil immersion objective in light microscopy. It is still sometimes also used to clarify emeralds. Cedar leaf oil from "Cedrus atlantica" does not contain thujone. Cedarwood oil is a mixture of organic compounds considered generally safe by the FDA as a food additive