Creosote

[2] Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties, see image).

Samples may be found commonly inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke.

Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived from Greek κρέας (kreas) 'meat' and σωτήρ (sōtēr) 'preserver'.

[4][5] The wood-tar variety has been used for meat preservation, ship treatment, and such medical purposes as an anaesthetic, antiseptic, astringent, expectorant, and laxative, though these have mostly been replaced by modern formulations.

[citation needed] The term creosote has a broad range of definitions depending on the origin of the coal tar oil and end-use of the material.

Creosote was first discovered in its wood-tar form in 1832, by Carl Reichenbach, when he found it both in the tar and in pyroligneous acids obtained by a dry distillation of beechwood.

[3] Soon afterward, in 1834, Friedrich Ferdinand Runge discovered carbolic acid (phenol) in coal-tar, and Auguste Laurent obtained it from "phenylhydrate", which was soon determined to be the same compound.

Despite evidence to the contrary, his view held sway with most chemists, and it became commonly accepted wisdom that creosote, carbolic acid, and phenylhydrate were identical substances, with different degrees of purity.

Because wood-tar creosote is used for its guaiacol and creosol content, it is generally derived from beechwood rather than other woods, since it distills with a higher proportion of those chemicals to other phenolics.

The alkaline solution is then separated from the insoluble oily layer, boiled in contact with air to reduce impurities, and decomposed by diluted sulfuric acid.

[27][28] He recommends cedria to ease the pain in a toothache, as an injection in the ear in case of hardness of hearing, to kill parasitic worms, as a preventive for infusion, as a treatment for phthiriasis and porrigo, as an antidote for the poison of the sea hare, as a liniment for elephantiasis, and as an ointment to treat ulcers both on the skin and in the lungs.

It was prescribed to quell the irritability of the stomach and bowels and detoxify, treat ulcers and abscesses, neutralize bad odors, and stimulate the mucous tissues of the mouth and throat.

Use for this purpose was dropped, until the idea was revived in 1876 by British doctor G. Anderson Imlay, who suggested it be applied locally by spray to the bronchial mucous membrane.

[42] Germ theory had been established by Pasteur in 1860, and Bouchard, arguing that a bacillus was responsible for the disease, sought to rehabilitate creosote for its use as an antiseptic to treat it.

[citation needed] The guaifenesin developed by Eldon Boyd is still commonly used today as an expectorant, sold over the counter, and usually taken by mouth to assist the bringing up of phlegm from the airways in acute respiratory tract infections.

Polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, benzenes, toluenes, ethylbenzenes, and xylenes (BTEX) Phenols, cresols, xylenols, and naphthols Pyridines, quinolines, benzoquinolines, acridines, indolines, and carbazoles Benzothiophenes Dibenzofurans Aniline, aminonaphthalenes, diphenylamines, aminofluorenes, and aminophenanthrenes, cyano-PAHs, benz acridines Coal-tar creosote is greenish-brown liquid, with different degrees of darkness, viscosity, and fluorescence depending on how it is made.

The tar acids are the strongest antiseptics but have the highest degree of solubility in water and are the most volatile; so, like with wood-tar creosote, phenols are not the most valued component, as by themselves they would lend to being poor preservatives.

[62] Lastly, creosote contains a small number of aromatic amines produced by the other substances during the distillation process and likely resulting from a combination of thermolysis and hydrogenation.

[65] In the early 20th century, American-produced creosote oils typically had low amounts of anthracene and high amounts of naphthalene, because when forcing the distillate at a temperature that produces anthracene the soft pitch will be ruined and only the hard pitch will remain; this ruined it for use in roofing purposes (which was common before widespread availability of cheap oil bitumen) and only left a product which wasn't commercially useful.

As a fuel, it was used to power ships at sea and blast furnaces for different industrial needs, once it was discovered to be more efficient than unrefined coal or wood.

[68] Creosoted wood blocks were a common road-paving material in the late 19th and early 20th centuries, but ultimately fell out of favor because they did not generally hold up well enough over time.

Coal-tar creosote, despite its toxicity, was used as a stimulant and escharotic, as a caustic agent used to treat ulcers and malignancies, cauterize wounds, and prevent infection and decay.

[77][78] The United States Environmental Protection Agency regulates the use of coal-tar creosote as a wood preservative under the provisions of the Federal Insecticide, Fungicide, and Rodenticide Act.

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.

ATSDR 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, unconsciousness, and even death.

This creates a compounding problem, because the creosote deposits reduce the draft (airflow through the chimney) which increases the probability that the wood fire is not getting enough air for complete combustion.

[89] Even though creosote is pressurized into the wood, the release of the chemical – and resulting marine pollution – occurs due to many different events: During the lifetime of the marine piling, weathering occurs from tides and water flow which slowly opens the oily outer coating and exposes the smaller internal pores to more water flow.

[7] This study showed that an exposure time of 24–96 hours on various shrimp and fish species affected the growth, reproduction, and survival functions of the organisms for most of the compounds tested.

[107] Even though many studies conduct testing under experimental or enriched conditions, oxidation-reduction reactions occur naturally and allow for chemicals to go through processes such as biodegradation, outlined above.

Cresol (m-, p-, and o-), phenol, guaiacol, and xylenol (1,3,4- and 1,3,5-) all are acute aquatic hazards[citation needed] prior to going through chemical reactions with the sediments.