Creosote is the name used for a variety of products including
wood creosote and
coal tar creosote. Wood creosote is created by high temperature treatment of
beechBeech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.The leaves of beech trees are entire or sparsely toothed, from 5–15 cm long and 4–10 cm broad...
and other woods, or from the
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
of the
Creosote bushLarrea tridentata, known as creosote bush , is a flowering plant in the family Zygophyllaceae...
.
The term creosote, however, is most commonly used to refer to coal tar creosote. Coal tar creosote is an EPA-registered wood preservative. It is distilled from crude coke oven tar, and is mainly composed of polycyclic aromatic hydrocarbons (PAHs), but also contains
phenolPhenol, also known as carbolic acid, is a toxic, white crystalline solid. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group bonded to a phenyl ring, making it an aromatic compound.-Phenols:...
s and cresols.
The term is also used to refer to the buildup of carbon materials in chimneys from wood-burning fires
Wood creosote is a colourless to yellowish greasy liquid with a smoky odor and burned taste.
Creosote is the name used for a variety of products including
wood creosote and
coal tar creosote. Wood creosote is created by high temperature treatment of
beechBeech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.The leaves of beech trees are entire or sparsely toothed, from 5–15 cm long and 4–10 cm broad...
and other woods, or from the
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
of the
Creosote bushLarrea tridentata, known as creosote bush , is a flowering plant in the family Zygophyllaceae...
.
The term creosote, however, is most commonly used to refer to coal tar creosote. Coal tar creosote is an EPA-registered wood preservative. It is distilled from crude coke oven tar, and is mainly composed of polycyclic aromatic hydrocarbons (PAHs), but also contains
phenolPhenol, also known as carbolic acid, is a toxic, white crystalline solid. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group bonded to a phenyl ring, making it an aromatic compound.-Phenols:...
s and cresols.
The term is also used to refer to the buildup of carbon materials in chimneys from wood-burning fires
Wood creosote
Wood creosote is a colourless to yellowish greasy liquid with a smoky odor and burned taste. Other than looks and taste, the chemical makeup is totally different than coal tar creosote. It is made of
guaiacolGuaiacol is a naturally occurring organic compound with the formula C
6H
4. This colourless aromatic oil is derived from guaiacum or wood creosote. Samples darken upon exposure to air and light. Guaiacol is present in wood smoke, resulting from the pyrolysis of lignin...
,
creosolCreosol is an ingredient of creosote. Compared with phenol, creosol is a less toxic disinfectant.-Sources :* Coal tar creosote* Wood creosote* Reduction product of vanillin using zinc powder in strong hydrochoric acid...
,
o-cresolortho-Cresol, also 2-methylphenol, is a phenol, with formula C6H4.It is an isomer of p-cresol, m-cresol and anisole-Chemistry:Cresols are organic compounds which are methylphenols...
, and
4-ethylguaiacol4-Ethylguaiacol, often abbreviated to 4-EG, is a phenolic compound with the molecular formula C9H12O2. It is produced along with 4-ethylphenol in wine and beer by the spoilage yeast Brettanomyces...
, plant phenolics, rather than petrochemicals.
Wood creosote has been used as a disinfectant, a
laxativeLaxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and bowel examinations, and may be supplemented by enemas in that...
, and a cough treatment, but these have mostly been replaced by newer medicines.
The popular Japanese
KampoKampÅ medicine is the Japanese study and adaptation of Traditional Chinese medicine. The basic works of Chinese medicine came to Japan between the 7th and 9th centuries. Since then, the Japanese have created their own unique herbal medical system and diagnosis...
anti-diarrheic Seirogan has 133 mg wood creosote (from beech, maple or oak wood) per adult dose as its primary ingredient.
http://www.seirogan.co.jp/english/seihin/seirogan/index.html
Wood creosote also protects wood from shrinking from the sun, losing its colour and moulding from the rain. Many companies use creosote to protect wood.
Coal tar creosote
Another form of creosote is coal tar creosote. Coal tar creosote is the most widely used wood
preservativeA preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes.-Preservatives in wood:...
in the world. It is a thick, oily liquid typically amber to black in colour. The American Wood Preservers' Association states that creosote "shall be a distillate derived entirely from tars produced from the carbonization of bituminous coal." Coal tar used for certain applications may be a mixture of coal tar distillate and coal tar.
See, AWPA Standards
The prevailing use of creosote in the United States is to preserve wooden utilities/telephone poles, railroad cross ties, switch ties and bridge timbers from decay. It is registered with USEPA for this purpose.
Coal tarCoal tar is a brown or black liquid of high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal is...
products are also used in medicines to treat diseases such as
psoriasisPsoriasis is a chronic, non-contagious autoimmune disease that affects the skin and joints. It commonly causes red, scaly patches to appear on the skin. The scaly patches caused by psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly...
, and as animal and bird repellents, insecticides, animal dips, and fungicides. Some over the counter anti-dandruff shampoos contain coal tar solutions. Due to its carcinogenic character, the European Union has banned the sale of creosote treated wood and requires that the sale of creosote be limited to professional users.
Health effects of coal tar creosote
According to the Agency for Toxic Substances and Disease Registry (ATSDR), eating food or drinking water contaminated with high levels of coal tar creosote may cause a burning in the mouth and throat, and stomach pains.
ATDSR also states that brief direct contact with large amounts of coal tar creosote may result in a rash or severe irritation of the skin, chemical burns of the surfaces of the eyes, convulsions and mental confusion, kidney or liver problems,
unconsciousnessUnconsciousness, more appropriately referred to as loss of consciousness or lack of consciousness, is a dramatic alteration of mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is an illustration...
, and even
deathDeath is the termination of the biological functions that define a living organism. It refers to both a particular event and to the condition that results thereby. The true nature of the latter has for millennia been a central concern of the world's religious traditions and of philosophical...
. Longer direct skin contact with low levels of creosote mixtures or their vapors can result in increased light sensitivity, damage to the
corneaThe cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43...
, and skin damage. Longer exposure to creosote vapors can cause
irritationIrritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...
of the
respiratory tractIn humans the respiratory tract is the part of the anatomy that has to do with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...
.
The
International Agency for Research on CancerThe International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....
(IARC) has determined that coal tar creosote is probably carcinogenic to humans, based on adequate animal evidence and limited human evidence. It is instructive to note that the animal testing relied upon by IARC involved the continuous application of creosote to the shaved skin of rodents. After weeks of creosote application, the animals developed cancerous skin lesions and in one test, lesions of the lung. The
United States Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged to regulate chemicals and protect human health by safeguarding the natural environment: air, water, and land...
has stated that coal tar creosote is a probable human
carcinogenA carcinogen is any substance, radionuclide or radiation that is an agent directly involved in the promotion of cancer or in the increase of its propagation. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
based on both human and animal studies. As such, the Federal
Occupational Safety and Health AdministrationThe United States Occupational Safety and Health Administration is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970...
(OSHA) has set a permissible exposure limit of 0.2 milligrams of coal tar creosote per cubic meter of air (0.2 mg/m3) in the workplace during an 8-hour day, and the Environmental Protection Agency (EPA) requires that spills or accidental releases into the environment of one pound (0.454 kg) or more of creosote be reported to them.
There is no unique exposure pathway of children to creosote. Children exposed to creosote will probably experience the same health effects seen in adults exposed to creosote. It is unknown whether children differ from adults in their susceptibility to health effects from creosote.
A 2005 mortality study of creosote workers found no evidence supporting an increased risk of cancer death, as a result of exposure to creosote. Based on the findings of the largest mortality study to date of workers employed in creosote wood treating plants, there is no evidence that employment at creosote wood-treating plants or exposure to creosote-based preservatives was associated with any significant mortality increase from either site-specific cancers or non-malignant diseases. The study consisted of 2,179 employees at eleven plants in the United States where wood was treated with creosote preservatives. Some workers began work in the 1940s to 1950s. The observation period of the study covered 1979- 2001. The average length of employment was 12.5 years. One third of the study subjects were employed for over 15 years.
External links
- National Pesticide Information Center - Non-CCA Wood Preservatives
- Creosote fact sheet from the UK
The United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
Department for Business, Enterprise and Regulatory ReformThe Department for Business, Enterprise and Regulatory Reform was a United Kingdom government department. The department was created on 28 June 2007 on the disbanding of the Department of Trade and Industry , and was itself disbanded on 6 June 2009 on the creation of the Department for Business,...
- ATSDR creosote FAQ
- Tests of Creosoted Timber, Transactions of the American Society of Civil Engineers
The American Society of Civil Engineers is a professional body founded in 1852 to represent members of the civil engineering profession worldwide. It is the oldest national engineering society in the United States. ASCE's vision is to have engineers positioned as global leaders who strive toward...
, vol. LXX, Dec. 1910, by W. B. Gregory, from Project GutenbergProject Gutenberg, abbreviated as PG, is a volunteer effort to digitize and archive cultural works, to "encourage the creation and distribution of eBooks." Founded in 1971 by Michael S. Hart, it is the oldest digital library. Most of the items in its collection are the full texts of public domain...
- American Wood-Preservers' Association
- Creosote Council
- Status of creosote under European Union Directive 98/8/EC