The Tidewater Communities Project
Resource Page
COAL TAR*
Characteristics
Coal tars are by-products of the carbonization of coal to produce coke and/or natural gas. Usually, coal tars are viscous liquids or semisolids that are black or dark brown with a naphthalene-like odor. Coal tars are complex combinations of polycyclic aromatic hydrocarbons (PAHs), phenols, heterocyclic oxygen, sulfur, and nitrogen compounds. Coal tar creosote, coal tar, and coal tar pitch are mixtures of similar compounds, and are often referred to as creosotes. Creosote are created by high-temperature treatment of woods, coal, or resin from the creosote bush. Creosote prepared from coal tar is the most common form of creosote, and is the mostly widely used wood preservative in the United States.
Exposure to Coal Tar
Exposures to coal tar and coal tar products may take place in industrial and non-industrial settings and can occur through a number of different routes of exposure. Coal tar products are ingredients in medicines used to treat skin diseases (such as psoriasis). They are also used as animal and bird repellents, insecticides, animal dips, and fungicides. Coal tar, coal tar pitch
and coal tar pitch volatiles are used in road paving, roofing and industrial processes, so people working in these industries have the highest exposure. In addition, some herbal and dietary supplements contain coal tar (e.g. chaparral tea).
Environmental Protection Agency
Removal of coal tar wastes, Hoult Road Site, Fairmont, West Virginia
Effects on Health
If coal tar residues come in contact with skin, it can cause redness or a rash. In some people, the coal tar can cause a sunburn effect on skin. Eye irritation is another hazard if coal tar residues get in the eyes.
Ingesting herbal remedies containing creosote bush leaves may result in damage to the liver or kidneys. Large exposures (accidently or intentionally ingesting coal tar creosote) may result in a rash or sever irritation of the skin, chemical burns to the eye, mental confusion, kidney or liver problems, and even death. Longer exposure to lower levels of coal tar by direct skin contact or inhalation of vapors can result in increased sensitivity to sunlight, damage to the cornea, and skin problems (reddening, blistering, peeling). Longer exposure to vapors can also irate the respiratory tract. Skin cancer and cancer of the scrotum have also resulted from long exposure to low levels. These levels are much higher than the levels are likely to be exposed to in groundwater, air, or soil.
Studies of workers exposed to coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles in various industrial environments have found increased cancer risk involving a number of tissues including the respiratory tract, skin, lung, pancreas, kidney, scrotum, prostate, rectum, bladder, and central nervous system. Leukemia and lymphoma have also been diagnosed. These adverse effects are not apparent in patients undergoing coal tar therapy. Animal studies have demonstrated the carcinogenic potential of dermally-applied coal tar products. Workers using coal tar and coal tar creosote in wood preservative plants exhibited mild to moderate pulmonary restrictive and obstructive deficits. A residential survey conducted by the Texas Department of Health as part of a site surveillance program did not detect any adverse respiratory effects among residents of a housing development built on contaminated land formerly occupied by a coal tar creosote wood treatment plant.
Recommendations
Minimal Risk Levels (MRLs) for wood creosote, coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles cannot be determined because available data are insufficient for acute, intermediate, and chronic exposures via the oral and inhalation routes. In addition, coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles are extremely complex in their chemical compositions, thereby further complicating the MRL derivation process. The MRL is an estimate of the daily human exposure to a substance (noncarcinogenic) that is likely to be without an appreciable adverse risk over a specified duration of exposure. The primary limitation to deriving the MRL for these agents is that the MRL is, generally, based on measured biological effects of a single substance and not on the effects produced by mixtures of chemicals, which is the chemical nature of the wood creosotes, coal tar creosote, coal tar, and coal tar pitch.
* Compiled by Elizabeth Limbrick, New Jersey Institute of Technology Technical Assistance to Brownfield Communities (TAB) Program. Source: http://www.atsdr.cdc.gov/toxprofiles/tp85-c2.pdf