2. Relevance to Public Health 2.1 Background and Environmental Exposures to Creosote in the United States

Wood creosotes are derived from the resin from leaves of the creosote bush (Larrea, referred to herein as creosote bush resin) and beechwood (Fagus, referred to herein as beechwood creosote). Creosote bush resin consists of phenolic (e.g., flavonoids and nordihydroguaiaretic acid), neutral (e.g., waxes), basic (e.g., alkaloids), and acidic (e.g., phenolic acids) compounds. The phenolic portion comprises 83–91% of the total resin, while nordihydroguaiaretic acid accounts for 5–10% of the dry weight of the leaves. Extracts of the creosote bush are used in homeopathic medicine, and the leaves are used to make an infusion called chaparral. Beechwood creosote consists mainly of phenol, cresols, guaiacol, xylenol, and cresol. It is a colorless or pale yellowish liquid, and has a characteristic smoky odor and burnt taste. It had therapeutic applications in the past as a disinfectant, laxative, and stimulating expectorant, but it is not a major pharmaceutical ingredient today in the United States. Exposure to wood creosotes appears to be confined to dermal contact with the plants and ingestion of plant extracts such as chaparral.