Pentachlorophenol, a wood preservative, (also known as PCP or penta) conclusively has been established as a carcinogen in laboratory studies.  It causes cancer, the severest of personal injuries, and progresses to wrongful death.
Because there is a latency period of many years between exposure and diagnosis, health care providers, union representatives, workers’ compensation attorneys and trial lawyer practitioners should inquire of anyone who is suffering from blood or lymph cancers who has worked in the forestry, lumber mill, window manufacturing, paint, and construction industries of possible occupational exposures to penta and, in addition, whether they have lived in direct contact with treated wood, such as found in log cabins.

We have represented employees of the Simpson Lumber Company who worked on the same planing unit at the Arcata remanufacturing, or finishing, mill during the 1970’s and who have subsequently suffered acute leukemias and non-Hodgkins lymphoma.

The success lawsuit was brought against U.S. Plywood, Champion Papers, Roberts Consolidated Industries, Beecham Home Improvement Products, and DAP, Inc.

Few personal injury lawyers and workers’ compensation lawyers have little understanding of the personal injuries and wrongful deaths caused by chemical exposures and California’s plaintiffs’ bar, in general, has failed to organize on these issues and to develope the technical expertise to assist individual practitioners in identifying potential third party actions, preserving evidence and gathering the proof needed to properly represent workers injured and killed by toxic chemicals.

This current situation with regard to PCP has developed despite a strong social commitment to a safe environment, an extensive logging industry and the fact that forestry workers specifically have been identified in the literature as primary victims of PCP induced carcinomas, among other occupationally exposed workers.

Our research also shows that the application of PCP in log cabin homes in the Midwest has been the primary legal battleground concerning this carcinogen and only by chance did we located Midwest counsel with expertise in this aspect of PCP litigation.

It is for these reasons we share our research on pentachlorophenol, and that of others, with the hope that we will generate a network of informed professionals for the benefit of our clients and the general public.


Pentachlorophenol has been used as an insecticide, fungicide, and herbicide, in industry, agriculture and domestic applications, but it is primarily a wood preservative. PCP is an extremely dangerous carcinogen when it is used to preserve wood for inside applications Environmental Health Criteria 71, Pentachlorophenol, World Health Organization, Geneva, 1987, pp. 11-12.

Pentachlorophenol has been used for years to preserve telephone poles, fence posts, and water exposed decking. In the 1970’s it was introduced to preserve finished mill work, casements, mullions, and to treat perimeter wall logs in log home kits marketed to the public.

Pentachlorophenol is a halogenated hydrocarbon, composed of a benzene ring to which is attached a hydroxide radical making a phenol which is then chlorinated. Byproduct contaminants of the process include tetrachlorophenol, hexachlorobenzene and various dioxins and furans. Hexachlorodibenzodioxin, an extremely toxic dioxin, has appeared in commercially produced pentachlorophenol in the United States during the 1970s in amounts ranging up to 100 parts per million. A purer grade of commercial pentachlorophenol was developed, manufactured and sold by the Dow Chemical Company in response to concerns raised by the Environmental Protection Agency about the high level of dioxins in PCP which was being marketed in the early 1970’s. The newly developed product, Dowicide E. C. – 7, contained approximately 1% of the dioxin contamination found in the technical grade of pentachlorophenol used in the manufacture of Woodlife, a mineral spirit solution used by Simpson as a fungicide and originally marketed by U.S. Plywood. It subsequently was manufactured and sold by the successors to U.S. Plywood: Champion Papers, Roberts Consolidated Industries, Beecham Home Improvement Products, and DAP, Inc.

Toxicity and Carcinogenicity

Pentachlorophenol is a known toxic chemical. It is readily absorbed by lung, skin and stomach. While there may be difference in the biological response of rabbits and humans to 10% solution of pentachlorophenol, the probable oral and dermal lethal doses for a 150 pound person, based on the animal toxicity literature, is 1.09 ounces orally and 4.4 ounces dermally.

The body absorbs PCP and discharges it in a number of ways. While much of it is excreted in urine, it accumulates in tissues, particularly muscle, bone marrow, and fat. Braun, et al., The Pharmokinetics and Metabolism of Pentachlorophenol in Rats [1977], Toxical. Appl. Pharmacol. 41:395-406.

Pentachlorophenol is eliminated mainly through urine and the half life of elimination by urine has been observed to be as long as 18 to 20 days. Uhl, et al., Pharmokinetics of Pentachlorophenol in Man [1986], Arch. Toxicol. 58:182-186.

The “no effect” and “lethal” dose limits of pentachlorophenol are not greatly different. For example, at a dose of 80 milligrams per kilogram, no experimental animals died. At a dose of 100 milligrams 83% died and at 110 milligrams 100% died. Kehoe, et al., Toxic Effects Upon Rabbits of Pentachlorophenol and Sodium Pentachlororphenate [1959], J. INd. Hyg. Tox. 21: 160.

Chronic toxicity associated with PCP first was reported in California Health in June, 1970 in the case of a woman who moved into a newly constructed home which had been treated with PCP. She experienced rapid weight loss, weakening and tightening in her chest, and symptoms which were suspected to be asthma and bronchitis. After leaving the structure her health improved.

German literature reports health problems due to residential exposure to PCP. Brandt and Schmidt, in an article entitled Chronische Lebererkrankung durch langjahrige Intoxikation im Haushalt mit Pentachlorophenol [1977], Deutschen Gesellschaft fur innere Medizin, pp. 1609-11, reported fluctuating abnormal liver enzymes directly associated with moving into and out of a dwelling which had its interior treated with PCP. Later, Gebefugi reported health problems associated with residential interior exposure to pentachlorophenol. Gebefugi, et al., Occurrence of Pentachlorophenol in Enclosed Environments [1979] Ecotoxicology and Environmental Safety 3:269- 300.

The health effects observed in both the occupational and residential exposures, especially those related to the skin and respiratory tract are best explained by laboratory findings involving immune system studies of laboratory animals. In a series of experiments reported in the early 1980’s, Nancy Kirkvliet, et al., found that technical grade pentachlorophenol causes immune suppression in animals which she has linked to dioxins contained in pentachlorophenol and found that hepta and hexa dioxin are implicated. Kerkvliet, et al., Humoral Immunotoxicity of Polychlorinated Diphenyl Ethers, Penoxypheols, Dioxins and Furans Present as Contaminants of Technical Grade Pentachlorophenol [1985], Toxicology, 36:307-24 (see extensive articles cited).

In addition to suppressing the immune system, laboratory and epidemiological studies have shown technical grade PCP to be a carcinogen. Pentachlorophenol was a suspected carcinogen in 1978. Greene, et al., Familial and Sporadic Hodgkin’s Disease Associated with Occupational Wood Exposure, The Lancet, September 16, 1978, pp. 626-27; Goldstein, et al., Effects of Pentachlorophenol on Hepatic Drug/Metabolizing Enzymes and Porphyria Related to Contamination with Chlorinated Dibenzo-p- Dioxins and Dibenzo-Furans [1977] Biochem. Pharmacol. 26:1549-57.

Technical grade pentachlorophenol contains dioxins. Dioxins have been considered carcinogens in humans since the early 1970s. Ton That Tung, Le Cancer Prmaire Due Foie Au Viet-nam [1973], 99:427-36; Hardell, Soft-Tissue Sarcomas and Exposure to Phenoxy Acids: A Clinical Observation [1977] Lakartidningen 74:2753-54.

Like technical grade PCP, phenoxy acids also contain dioxins as contaminants. Adverse health effects associated with exposure to dioxins and furans are well documented. Schwetz et al., The Effect of Purified and Commercial Grade Pentachlorophenol on Rat Embryonal and Fetal Development [1974], Toxicology and Applied Pharmacology 28:151-61. Dioxins were considered carcinogens in rodents since the late 1970’s Kociba, et al., Results of a Two Year Chronic Toxicity and Oncogenicity Study of 2,3,7,8- Tetrachlorodibenzo-p-Dioxin in Rats [1978], Toxicology and Applied Pharmacology 46:279-303; Van Miller et al., Increased Incidence of Neoplasms in Rats Exposed to Low Levels of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin [1977], Chemosphere 10:625; Muranyi-Kovacs, et al., Bioassay of 2,4,5- Trichlorophenoxyacetic Acid for Carcinogenicity in Mice [1976] British Journal of Cancer 33:626.

Government Response

The United States Department of Agriculture’s Forest Products Laboratory has vigorously opposed the use of both pentachlorophenol and creosote for residential use and warned these products “should never be used inside . . . for any reason.” U.S.D.A. Forest Service Forest Products Laboratory, General Technical Report FPL-11, Protecting Log Cabins from Decay [1977], p.2.

Unfortunately vaporization of PCP cannot be inhibited by paint, varnish, or shellac when treated wood is used for an interior application and in log homes sealants are ineffective according to the EPA. Hosenfeld, et al., Pentachlorophenol in Log Homes: A Study of Environmental and Clinical Aspects, Environmental Protection Agency Contract Nos. 68-02- 3938 and 68-02-4252 MRI Project Nos. 8201-A(11) and 8801 A(02) COEH Subcontract No. 117-7900-17 and 180-7900-9, pp. 1-195, December 11, 1986.

The Log Home Litigation Record

In Perkins v. Northeastern Log Homes, Inc. Roberts Consolidated Industries and DAP, Inc., U.S.D.C. Western District of Kentucky, Omaha attorneys Richard McMillin and Timothy Cuddigan, whose work significantly contributed to this article, are seeking recovery for PCP exposure occurring in 1978 when Mrs. Perkins used a solution of bleach to scrub PCP stains from the interior logs of her newly constructed log home. In 1986 Mrs. Perkins was diagnosed as suffering from non-Hodgkin’s lymphoma, but did not discover the connection to PCP until 1989. This is McMillin’s and Cuddigan’s second log home case against Northesatern Homes having previously represented plaintiffs in Johnson v. Northeastern Log Homes in U.S.D.C. in Omaha, Nebraska in 1985. They report that Roberts Consolidated Industries had special reason to be aware of the adverse health effects in humans caused by residential interior exposure to pentachlorophenol because its PCP-based product, Woodlife, was involved in several cases in the 1970s. In Fertig v. U.S. Plywood, Polk County District Court, Des Moines, Iowa, plaintiffs claimed adverse health effects and property damage caused by the interior use of Woodlife containing PCP. The makers of Woodlife also were sued by the Tran King family in Idaho Falls, Idaho in 1976 for toxic exposure causing personal injuries and property damage.

According to their research, Northeastern Log Homes of Omaha had direct knowledge of the adverse health effects of Woodlife containing PCP that caused it in late 1978 to cease the use of Woodlife for dip-treating perimeter logs. Despite knowledge of these concerns Northeastern took no steps to affirmatively warn its customers about the hazards created by its use of Woodlife, even though in 1981 Dr. Vernon N. Houk, Acting Director for the Center for Environmental Health of the Center for Disease Control, specifically recommended that Northeastern inform its customers of possible health risks from PCP exposure in its log homes.

Cancer in the Lumber Mill Industry

Numerous studies link occupations in the lumber and sawmill industry with acute leukemias, Hodgkin’s and non-Hodgkin’s lymphomas and multiple myelomas. Milham, Study of Mortality Experience of AFL-CIO United Brotherhood of Carpenters and Joiners of American, 1969-70 [1974], DHEW Pub. No. 74-129, Springfield, Virginia, National Technical Information Service; Jappinen, et al., Cancer Incidence of Workers in Finnish Sawmill [1989], Scand. J. Work Environ. Health 15:18-23; Morton and Marjanovic, Leukemia Incidences By Occupation in Portland-Vancouver Metropolitan Area [1984] Am. J. Ind. Med. 6:185-205; Burkart, Leukemia in Hospital Patients with Occupational Exposure to Sawmill Industry[1982], West. J. Med. 137:440-441; Erickson, et al., Study on Malignant Mesenchymal Tumors of Soft Tissues and Exposure to Chemical Substances [1979], Lahartidningen 76:3872-75; Hardell, Malignant Lymphoma of Histiocytic Type and Exposure to Phenoxyacetic Acids or Chlorophenols [1979], Lancet i:56; Milham and Hessler, Hodgkin’s Disease in Woodworkers [1967] Lancet ii: 136-37.

It is thought that exposures to chlorophenol herbicides in the lumber industry have been the principle cause for the increased risk of hematopoietic cancers. Erickson, ibid.; Hardell, ibid. These factors are strongly suspected as potentially causative in our Humboldt County action in which Simpson employees suffered a 16 fold increase in the number of blood cancers over statistically expected malignancies.

Hardell in a 1981 study of forestry workers exposed to chlorophenols found an eight-fold increase in soft tissue sarcomas and malignant lymphomas due to herbicides containing chlorophenols, primarily PCP. Hardell, et al., Malignant Lymphoma and Exposure to Chemicals, Especially Organic Solvents, Chlorophenols and Phenoxy Acids: A Case-Control Study [1981], British Journal of Cancer, 43:169-76.

Plan for Action

In Humboldt County a study by the State Department of Health of the reported cancers shows a latency period from exposure to a carcinogen, until the clinical detection of cancer, was fourteen to seventeen years.

The clear significance of this long latency period is that other cases can yet be expected and vigilant health care providers, union representatives, and lawyers must always suspect the potential for chemically induced leukemias and lymphomas in woodworking, lumber, and forestry workers.

With cancer taking a devastating social and economic toll, government funding for the placement of industrial hygienists in every significant cancer care center for the purpose of taking detailed histories of potential exposures should be a top health care priority in order to identify industrial practices and products for which further study and precautions are necessary.

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Richard Alexander