2,3,4,5,6-Pentachlorophenol

IUPAC name Pentachlorophenol Molecular formula C6HCI5O Toxicity class USEPA II WHO lb 

Uses Pentachlorophenol is covered by the USEPA under RUP for preservation of wood material and as a GUP for other purposes.14,48 PCP was one of the most heavily used pesticides in the United States. Now, only certified applicators can purchase and use PCP. It is still used in industry as a wood preservative for 

Studies have shown that PCP causes adverse effects to the liver, kidneys, blood, lungs, CNS, immune system, and gastrointestinal tract both after a short-or long-term exposure.60,61 Direct contact with PCP causes irritation to the skin, eyes, and mouth, particularly when it is a hot vapor. In view of its importance during earlier years, extensive studies of Braun and associates61 63 demonstrated the metabolism and pharmacokinetic disposition of PCP in rats, nonhuman primates, and humans. All these studies indicated the adverse effects of PCP to animals and humans.59-67 

The pesticide pentachlorophenol (PCP) is a typical example of a toxic chlorinated compound that is harmful to the environment. Because large amounts of this substance were produced and used in the past and because of its relatively high volatility and poor biological degradability, it is one of the chemicals that is of ubiquitous occurrence. 

PCP enters the human organism via the skin, the lungs and the gastrointestinal tract, and, while the symptoms of acute intoxication with this substance are described in the literature, the long-term harmful effects of prolonged exposure in the home both to PCP and to impurity levels of dioxin, a possible by-product of PCP manufacture, are currently attracting increasing attention and discussion. 

Like PCP, the insecticide lindane found a broad spectrum of application in wood preservation and for the treatment of pests affecting soil and forests. Because of the relatively high volatility and slow rate of decomposition of lindane in the environment, this substance, like PCP, also occurs ubiquitously. Table 9-2 gives toxicity data and levels of occurrence of lindane in the environment. 

1 ECW Exposure equivalent for carcinogenic substances at the workplace relationship between concentration in air and concentration of the substance or its metabolites in the biological material 

Again like PCP, lindane enters the body via the lungs, skin and gastrointestinal tract, and special attention must be paid to illnesses that can be caused by exposure over many years to both the compound itself and to the toxic impurities produced during its manufacture. 

Eisler, R. 1989. Pentachlorophenol hazards to fish, wildlife, and invertebrates a synoptic review. U.S. Fish Wildl. Serv. Biol. Rep. 85(1.17), 72 pp. 

Eisler, R. 2000. Pentachlorophenol. Pages 1193-1235 in Handbook of Chemical Risk Assessment Health Hazards to Humans, Plants, and Animals. Volume 2, Organics. Lewis Publishers, Boca Raton, Florida. 

In the United States between 1976 and 1980, PCP was present in the urine of 71.6% of the general population, suggesting that almost 112 million individuals aged 12-74 years had been exposed to PCP. 

Data are scarce on PCP effects on wildlife, although it is speculated that no wildlife losses should occur under normal PCP application conditions and that chronic toxicity would not be serious because PCP is rapidly excreted. However, mortality was heavy in two species of bats that came into contact with PCP-treated timbers up to 14 months after treatment. Wood preservatives, including PCP, are implicated in decline of bat population in the United Kingdom. Furthermore, evidence accumulating on the harmful effects of PCP to domestic animals suggests that the chemical may have considerable adverse effects on other 

World Health Organization Concise International Chemical Assessment Document (CICAD) 34, Chlorinated Napthalenes. pp 1-40, Geneva, International Programme on Chemical Safety (IPCS), 2001 

Ward EM, Ruder AM, Suruda A, et al Acute and chronic liver toxicity resulting from exposure to chlorinated naphthalenes at a cable manufacturing plant during World War II. Am JlndMed 30(2) 225-233, 1996 

Synonyms Penta PCP, penchlorol pen-tachlorophenate Santophen 20 Dowicide 7 

Physical Form. White to tan needle-like crystals 

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Constituents. Complex halogenated organic compounds have been widely used in commerce in the last fifty years. A few representative examples are shown in Eigure 9 pentachlorophenol has been widely used as a wood preservative, and also for termite control. 

A major concern when remediating wood-treatment sites is that pentachlorophenol was often used in combination with metal salts, and these compounds, such as chromated copper—arsenate, are potent inhibitors of at least some pentachlorophenol degrading organisms (49). Sites with significant levels of such inorganics may not be suitable candidates for bioremediation. 

Pentachlorophenol is readily degraded in biofHm reactors (53), so bioremediation is a promising option for the treatment of contaminated groundwater brought to the surface as part of a pump-and-treat operation. 

The synthesis of chlorarul [118-75-2] (20) has been improved. The old processes starting from phenol or 2,4,6-trichlorophenol have been replaced by new ones involving hydroquinone chlorination. These processes allow the preparation of chlorarul of higher purity, avoiding traces of pentachlorophenol. Different types of chlorination conditions have been disclosed. The reaction can be performed according to the following stoichiometry, operating with chlorine in aqueous acetic acid (86,87), biphasic medium (88), or in the presence of surfactants (89). 

Phenolics. Phenol (qv) and the chlotinated phenoHcs formerly comprised the largest class of iadustrial antimicrobials (see Chlorophenols). Table 5 shows the remaining phenoHcs of importance. Use of pentachlorophenol has been severely restricted only one manufacturer suppHes product for the wood preservation market. 

Common examples of compounds that are amenable to carbon adsorption are aromatics (benzene, toluene) and chlorinated organics (trichloroethylene, trichloroethane [71-55-6, 75 -(9(9-j5y, tetrachloroethylene, polychlorinated biphenyls (PCBs), DDT /T(9-77-77, pentachlorophenol [87-86-5J. Compounds that are not adsorbed effectively by carbon include ethanol [64-17-5], diethylene glycol [111-46-6], and numerous amines (butylamine [109-73-9, 13952-84-6, 75-64-9], triethanolamine [102-71-6], cyclohexylamine [108-91-8], hexamethylenediamine [108-91-8] (1). Wastewater concentrations that are suitable for carbon adsorption are generally less than 5000 mg/L. 

Wood preservatives ate appHed either from an oil system, such as creosote, petroleum solutions of pentachlorophenol, or copper naphthanate, or a water system. Oil treatments ate relatively inert with wood material, and thus, have Htde effect on mechanical properties. However, most oil treatments require simultaneous thermal treatments, which ate specifically limited in treating standards to preclude strength losses (24). 

The best protection for wood against the attack of decay fungi, insects, or marine borers is obtained by applying preservatives under pressure before installation (61,62). Both oil-type preservatives, such as creosote or petroleum solutions of pentachlorophenol, and waterborne preservatives, such as copper-chrome arsenate and ammoniacal-copper arsenate, are used when wood is to be in direct contact with the ground or in the marine environments. 

Pentachlorophenol. Because of the high melting temperature of pentachlorophenol, C HCl O, its preparation makes it necessary to raise the temperature progressively throughout chlorination. The presence of Lewis acid catalysts is essential. The most commonly used of these are AlCl and FeCL. 

Polychlorophenoxyphenols are the principal impurity in mixtures of tetrachlorophenols and pentachlorophenols. Traces of polychlorodibenzoparadioxins and polychlorodibenzofurans can also be present if the chlorination is not conducted correctiy. 2,3,7,8-Tetrachlorodibenzoparadioxia [1746-01 -6] which is highly toxic, has never been detected in any products derived by chlorination. 

Rhc ne-Poulenc, with a capacity of around 20,000 t/yr, is the world s leading producer of light chlorophenols. Excluding the unknown factors for which no statistics are available (China, Russia), the market for pentachlorophenol can be estimated at - 25, 000 t/yr. The principal producers of pentachlorophenol are given ia Table 4. 

The main applications of mono-, di-, or ttichlorophenols are in agrochemicals and for pentachlorophenol in wood protection. 2-Chlorophenol is used chiefly in the manufacture of an insecticide [41198-08-7] (55,56)... 

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