A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Michigan State University, Oregon State University, and University of California at Davis. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.
The results described in this profile are mostly from studies that were conducted using technical-grade PCP, because it is technical-grade PCP that people are exposed to when they use commercial PCP products.
Commercial (technical) grades of PCP commonly contain manufacturing by- products, such as dioxin (HxCDD), which can be more toxic than the PCP itself. Another contaminant in PCP is HCB (Hexachlorobenzene). The use of PCP is being phased out because of the discovery of these highly toxic contaminants (9). PCP is a Restricted Use Pesticide (RUP). Restricted Use Pesticides may be purchased and used only by certified applicators.
In 1988 the EPA announced further restrictions on the use of PCP as in the pulp and paper industry where it is used in paper coatings, sizing, adhesives and in inks. Registration for use in cooling towers and for certain oil well operations was also cancelled. The 1988 regulations also required compliance with dioxin (HxCDD) concentration limits in the final product.
Acute exposure to PCP can cause elevated temperature, profuse sweating, dehydration, loss of appetite, decreased body weight, nausea, uncoordinated movement and coma. Some of the symptoms may be due to the impurities in the formulation rather than the pentachlorophenol itself (9).
The oral LD50 of PCP for rats is 25-200 mg/kg, depending on the product quality. The oral LD50 for mice and rabbits is 130 mg/kg (6).
The dermal LD50 is 105 mg/kg for rabbits, 96-320 mg/kg for rats, and 261 mg/kg for mice (6). Acute dermal exposure of dogs, rabbits, rat, and guinea pigs to high doses of PCP causes dry wrinkled skin and loss of hair from topically treated areas, high blood pressure and fevor, motor weakness, rapid digestion, and extensive damage to the cardiovascular system.
The inhalation LD50 for rats is between about 10 and 225 mg/kg, and the mouse inhalation LD50 is 355 mg/kg (6).
In humans, the most common exposure to PCP is inhalation in the workplace. Abdominal pain, nausea, fever, and respiratory irritation result from PCP exposure (6). Inhalation of PCP at occupational levels causes eye, skin, and throat irritation, while high levels may affect the circulatory system and cause heart failure. Survivors of toxic exposures may suffer visual and central nervous system damage. Persons regularly exposed to PCP tend to tolerate higher levels of PCP vapors than persons having little contact with these vapors.
Prolonged exposure to PCP by humans may result in adverse reproductive effects that are associated with changes in the endocrine gland function and other changes in the body (immunological dysfunction). A number of women with histories of spontaneous abortion, unexplained infertility and menstrual disorders had elevated levels of pentachlorophenol and/or lindane in their blood (11). While this evidence suggests some relationship between reproductive problems and PCP and/or lindane, it does not prove that PCP or lindane were the direct cause of the problems (11).
In two-year studies of rats fed high doses of PCP, life spans were not changed, but liver and kidney changes were observed (6).
PCP causes lung, liver, kidney damage and contact dermatitis in humans. Extended periods of exposure to PCP results in persistent chloracne and damage to the nervous system. About two dozen fatalities due to accidental exposure to PCP in industry have been reported. Autopsies revealed changes in the brain, heart, kidneys, lungs, and liver.
Most wood treated with PCP solutions will "bleed." Bleeding refers to the movement of PCP solution from the interior to the surface of the wood. Whereas pure PCP can evaporate from the surface of the wood into the air, the impurities in the solutions may not. Because of its popular use as a wood preservative, the public could be exposed to low levels of PCP in outdoor wood structures of many kinds.
Cattle and other farm animals have ingested PCP by chewing and licking outdoor wood structures, or from being housed in wooden pens that were treated with PCP solutions. This has caused sickness and death in some of these animals. In late 1976, about 100 Michigan dairy farms had herd health problems due to contact with PCP-treated wood. However, pure PCP or contaminants were detected in the milk of only two herds.
Pure PCP is absorbed by aquatic organisms. Once absorbed by fish, pure PCP is rapidly excreted as is its metabolite, with a biological half-life of only 10 hours. Bioaccumulation may be significant. Several species of fish, invertebrates and algae have had levels of PCP that were significantly higher (up to 10,000 times) than the concentration in the surrounding waters (11). Biomagnification, that is the concentration of a compound as it passes up the food chain, has not been observed and is not expected to be an important source of exposure because PCP breaks down rapidly in living organisms (11).
After reaching soil, PCP is broken down by sunlight and bacteria (11), and can leave the upper soil layer by evaporation and leaching into groundwater. PCP degrades most rapidly in flooded or anaerobic (airless) soils. The degradation rate increases at higher temperatures and in the presence of organic matter in the soil. The half-life for bacterial degradation ranges from 15 to 48 days, in anaerobic and aerobic laboratory conditions respectively.
PCP is used in wood products that come in contact with water. PCP has been detected at very low levels in rivers and streams (0.01-16 ppb), surface water systems (1.3-12 ppb), and seawater (0.02-11 ppt) (3). The compound has also been found in ground water in California, Oregon and Minnesota at very low concentrations ranging from 0.06 ppt to 0.64 ppb (10). It has been detected in well water in Japan and in Canada also.
Once released into water, PCP may be degraded by sunlight or microorganisms or bind to sediments and suspended particles in water (3). It does not evaporate to a significant degree. In water, biodegradation occurs with a half-life ranging from hours to days. Most biodegradation occurs at the surface. PCP levels measured in the air of two towns were up to 0.93 and 7.8 ppt (7).
|NOEL:||1 mg/kg/day (rat)|
|TOL:||857 mg/l (30 degrees C)|
|TWA:||0.5 mg/m3 (skin)|
|STEL:||1.5 mg/m3 (skin)|
|Drinking water |
|Drinking Water Equivalent Level: 1/05 mg/L (8)|
|RfD:||0.003 mg/l (EPA)|
|Solubility in water:||0.0014 g/100g (20 degrees C) 0.0018g/100g (25 degrees C); 20 ppm (30 degrees C)|
|Solubility in solvents:||PCP is soluble in acetone, alcohols, ether, and hot benzene; it is slightly soluble in petroleum ether, carbon tetrachloride, and paraffins.|
|Melting point:||191 degrees C, anhydrous (2)|
|Boiling point:||309-310 degrees C|
|Vapor pressure:||1.7 x 10 to the minus 4 torr (20 degrees C)|
|Kow:||4900-141,300 (1, 3)|
|log Kow:||5.15 (4)|
|Kd:||1.82 x 10 to the minus 5|
|BCF:||273-4760 (calculated) (4)|