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What Compounds Make Up Creosote?

Creosote, sometimes referred to as pitch oil, has been used as a wood preservative since its patent date in 1716. Black to amber in color, creosote is invaluable to the railroad and marine industry, and is used to protect railroad ties, telephone poles and other exposed wood materials from insects and general decay.

  1. Manufacture

    • Creosote is derived from coal tar distilled at a high temperature. The coal is carbonized initially, and separated into three factions labeled as light, middle and heavy oil, or anthracene. The middle product is distilled once more at a high temperature creating creosote. Organizations such as the American Wood Preservers Association establish standards for the industry limiting source materials used during this process, as well as identifying the chemical characteristics of the product.

    Polycyclic Aromatic Hydrocarbons

    • Polycyclic Aromatic Hydrocarbons, or PAHs, are a family of over 10,000 organic compounds. Numerous useful products contain low levels of this compound. Within creosote manufacturing, it is categorized by either low or high weight. High weight PAHs raise more concern with environmental scientists due to slower biodegradation, though are not generally thought to be toxic. Links have been reported in some studies between high concentrations of PAH and cancer, or embryo mutation in fish and reptiles.

    Phenols

    • Phenol refers to a class of chemicals bonded to an aromatic hydrocarbon. As with PAHs, phenols are found in many homes, with domestic uses ranging from eye drops to mouthwash, but more predominately used in the plywood, automotive and appliance industries. The Environmental Protection Agency has formally identified phenol as a Group D carcinogen, or a non-classifiable compound. Most server effects are limited to oral consumption, though long-term exposure carries considerable risk to the blood and liver.

    Other Compounds

    • Approximately 85 percent of creosote is comprised of PAHs. The remaining composition is comprised of other heteronuclear aromatic compounds such as phenols, as well as hetrocylic oxygen, sulfur and nitrogen. Exact breakdowns are impossible due to variances in the source materials used to make it. Exposure to aromatic compounds could cause harm to humans and the environment, and because of this, these compounds are closely monitored by the EPA, Agency for Toxic Substances, OSHA, and International Agency for Cancer Research.

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