Pentachlorophenol: Toxicology and Environmental Fate by Brett Fisher However, Is Incomplete

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Pentachlorophenol: Toxicology and Environmental Fate By Brett Fisher however, is incomplete. Technical grade etrated the skin than had been estimated penta contains from 4 to 12 percent by EPA: 62 percent of the penta in oil Pentachlorophenol (penta or PCP) tetrachlorophenols, which are toxic in was absorbed and 16 percent of the was first introduced for use as a wood their own right. In addition, the high penta in water.13 Two recent studies of preservative in 1936 by Dow Chemical temperatures used in manufacturing sawmill workers exposed to water- Company and Monsanto Chemical Com- penta produce several contaminants in- based penta support these find- pany.1 Penta has since been used as an cluding hexachlorobenzene, dioxins, and ings.10,14 These findings suggest that herbicide on ornamental lawns, golf furans (see Figure 1).2 workers and others, such as those liv- courses, aquatic areas, and rights-of-way; There are two general methods for ing in treated homes or children who for control of subterranean termites; as preserving wood, the pressure process play on treated playground structures, an anti-microbial agent in cooling tow- and the non-pressure process. The pres- may be at greater risk from exposure ers, adhesives, latex paints, paper coat- sure-treating process involves placing through skin contact than estimated ings, cements used with food can ends the wood in a pressure-treating vessel by EPA. and seals, coatings in reusable bulk where it is immersed in the preserva- Although most people are not occu- food storage containers, photographic tive and then subjected to applied pres- pationally exposed to penta, research- solutions, leather tanneries, and pulp sure. The excess penta is vacuumed ers for the national Health and Nutri- and paper mills; and, as a disinfectant.2 from the vessel and the treated wood is tional Examination Survey II of the Na- It is marketed under the trade names removed, inspected, stored, and tional Center for Health Statistics found Santophen, Penchlorol, Chlorophen, shipped. In the non-pressure process, Pentacon, Penwar, Sinituho and Penta penta is applied to the surface of wood Figure 1 among others.3 by spraying, brushing, dipping, and soak- Pentachlorophenol and As of 1977, about 50 million pounds ing. This process is used for short-term Some of Its Contaminants of penta were produced annually in the wood protection in construction where Cl United States.2 In 1985, 35 million pounds the wood will be protected from expo- Cl Cl of penta were manufactured in the U.S.4 sure to soil or weather through brick or Vulcan Chemicals, located in Wichita, cement barriers. This process is also Cl Cl 5 Kansas, is penta’s sole U.S. producer. used to control sapstain fungi (fungi OH In 1988, the U.S. Environmental Protec- which leave a blue stain on wood) by Pentachlorophenol tion Agency (EPA) cancelled all uses of passing green lumber through a spray O penta except for its use as a wood pre- tunnel or by dipping the wood.7 Cl Cl servative.6 Cl Cl There are two manufacturing pro- Human Exposure cesses used to produce penta: (1) the People are exposed to penta in the Cl Cl direct chlorination of phenol, the workplace, in treated homes, indoor and O Boehringer process; and (2) the alkaline outdoor air, drinking water, and food. A hexachlorodibenzo-p-dioxin hydrolysis of hexachlorobenzene, the Penta can enter the body through inha- Dow process. In Europe, approximately lation, ingestion of contaminated food Cl Cl equal use is made of both methods. In or water, and skin contact with treated the US, penta is produced solely by the wood. Cl Cl 7 Boehringer process. Workers in wood preserving facilities, ClO Cl Chlorination of phenol in the sawmills and other workplaces who Boehringer process occurs in two stages. handle penta or treated wood receive A hexachlorodibenzofuran In stage one, chlorine is bubbled through the most significant exposures primarily Cl phenol at 105° F to yield tri- and through skin contact and secondarily Cl Cl tetrachlorophenols (phenols with three through air.6,7,8,9,10,11 Based on limited and four chlorine atoms respectively). data from animal studies, EPA has esti- Cl Cl In stage two, the temperature is gradu- mated that human skin absorbs 50 per- Cl ° ally increased to 130 F to keep the reac- cent of the amount of penta it is exposed Hexachlorobenzene tion mixture molten and to further chlo- to from oil-based formulations and 1 per- rinate the tri- and tetrachlorophenols to cent from water-based formulations.12 Cl form pentachlorophenol. The process, Researchers from the University of Cl Cl Washington, however, who applied amounts of penta to skin from human Cl Brett Fisher coordinates NCAP’s infor- cadavers to simulate levels at which OH mation services and groundwater cam- people are exposed found more pen- A tetrachlorophenol paign. 2 JOURNAL OF PESTICIDE REFORM / VOL. 11, NO. 1 penta in 79 percent of urine samples a higher metabolic rate and therefore treated containers.16 from the general population.15 In a breathe more often relative to body In addition, use of penta treated study of 179 Arkansas children, 100 weight and blood volume than adults. wood that comes in contact with live- percent of the urine samples tested They also suggested that skin contact stock can contaminate animal prod- positive for penta with an average level with treated walls could raise blood ucts with penta or its contaminants.26 of 14 parts per billion (ppb).16 Penta levels of penta in very young chil- In a study of pork and chicken in is also present in human fat tissues dren.21 Canada, 60 percent of 144 samples and human breast milk.17,18 In fact, sur- contained penta while half of 26 veys of the literature on human expo- chicken fat samples with high levels sure to penta indicate that people liv- of penta also contained hexa-, hepta-, ing in industrialized societies will gen- or octa- dioxins (those with six, seven, erally be contaminated with penta at “In a 1976 spot survey and eight chlorine atoms per dioxin concentrations of 1 to 100 ppb.19 of selected foods, penta molecule).27 In a survey of cow milk in One source of exposure to penta in Ontario, Canada, 57 percent of 359 the general population is from indoor residues ranging from 1 samples contained penta at an aver- air and dust. Residents of log homes to 100 ppb were found age of 29 ppb. The exposure of dairy treated with penta in Kentucky were in powdered dry milk, cattle to penta was attributed to penta found to have elevated levels of penta contaminated wood shavings or saw- in their blood (580 - 1,750 ppb) and soft drinks, bread, dust used as litter; direct contact be- urine (47 - 216 ppb). The source of candy bars, cereal, tween the cows and treated wood; and the exposure was continuous vapor- contact between feed and treated ization of penta from factory-treated noodles, rice, sugar, wood.28 logs. The youngest children had the and wheat.” highest blood levels of penta, even Human Toxicology though they spent as much time in Acute Toxicity: The acute toxicity the home as older children and of penta is believed to derive from its adults.20 ability to interfere with the produc- Researchers measuring levels of Penta, and other toxins, accumulate tion of energy at the cellular level. This penta in humans reported an average in household dust and can contribute interference (uncoupling of oxidative 40 ppb in the blood of the general to the total exposure of children and phosphorylation) causes increased population and an average of 420 ppb adults. Because of their lower body cell metabolism resulting in increased in 143 residents of log homes in nine weight, greater dermal contact with heat production.3,7,19 states. The children residing in penta dust, and frequent hand-to-mouth ac- A person may have up to about 100 treated log homes were found to have tivity, young children ingest at least ppb of penta in their blood and urine 1.8 times more penta in their blood 2.5 times more dust than adults.22 In a before they begin to experience ad- than adults. Because the primary route study of German homes, penta has verse effects.1 Levels of penta found of exposure to penta in homes is been found in house dust at levels that in various organs and fluids after fatal through the air, the researchers con- remained relatively high over time poisonings range from 20 to 145 ppm cluded that children could be ex- while levels in indoor air decreased.23 in adults. Levels of penta in children pected to have more penta in their In a study of Seattle homes, penta was and infants after fatal poisonings are blood than adults because they have found in house dust at an average level lower, indicating children are more of 3.4 parts per million (ppm). In two susceptible to penta than adults. Sur- of these homes, the penta may have veys of poisonings reported in the lit- Figure 2 Predicted Average Daily been tracked in from decks that had erature suggest that the largest single Intake of Pentachlorophenol 25 been treated with penta three and five dosage that produces no illness is little years before the samples were col- less than the fatal dosage.29 .9 5.1 .09 24 .5 lected. The most common symptoms of Because an estimated 96.5 percent those experiencing penta poisoning in- of the penta in the environment will clude stuffy nose, scratchy throat, and end up in soil, researchers looking at tears in the eyes. Skin contact can lead environmental sources of human ex- to contact dermatitis and, more rarely, posure to penta have calculated that chloracne. The chloracne is possibly the food chain, especially fruits, veg- a result of the contaminants in penta. etables, and grains, accounts for 99.9 A person experiencing systemic poi- air and water percent of human exposure to penta soning by penta would show symp- (Figure 2).25 In a 1976 spot survey of toms of profuse sweating and intense vegetables selected foods, penta residues rang- thirst, rapid breathing and heart rate, 93.4% ing from 1 to 100 ppb were found in fever, abdominal pain, nausea, weak- milk powdered dry milk, soft drinks, bread, ness, dizziness, anorexia, and nausea.3 beef candy bars, cereal, noodles, rice, Once in the body, penta is distrib- sugar, and wheat. The residues in the uted throughout and accumulates in fish Total average daily intake is 16.3 micrograms per day. grain and sugar items were attributed the liver, kidney, brain, spleen and fat. to the storage of these foods in penta- Although penta is not readily metabo-

JOURNAL OF PESTICIDE REFORM / SPRING 1991 3 lized in the body, it can attach (conju- concluded that penta does not cause penta’s contaminants since pure penta gate) to glucuronic acid and break down cancer.4 However, these studies are was not immunotoxic.38,39 to tetrachlorohydroquinone. Most penta, not considered adequate by present Health Standards: The American however, is eliminated from the body.4 standards that would make a negative Conference of Governmental Industrial In 1986, researchers at the Institute of response for carcinogenicity valid.7 Hygienists has established a thresh- Toxicology in Switzerland have found The International Agency for Research old limit value (TLV) of 0.5 milligrams that humans eliminate half of the penta on Cancer has classified penta as a per cubic meter for maximum daily they are exposed to in 17 days as penta Group 3 chemical for carcinogens (in- exposure to penta in the air in the or penta conjugated to glucuronic acid. adequate data in humans and ani- workplace. EPA has established a life- Their findings were supported by re- mals). EPA had originally classified time health advisory for exposure to ported cases of penta poisonings but penta as a Class D carcinogen (inad- penta in drinking water of 220 ppb. contrasted with previous findings of a equate animal evidence), but reclassi- The World Health Organization has 30 33 hour elimination half life in humans. fied it as a Class B2 carcinogen (prob- recommended a drinking water crite- Penta may therefore have a greater po- able human carcinogen) based on a rion of 10 ppb for penta.4 Development tential for accumulation and persistence 1988 National Toxicology Program of these standards did not take into in the human body than previously indi- study.35 The hexachlorobenzene and account the potential adverse health cated. hexachlorodibenzo-p-dioxin contami- effects of penta’s contaminants. Reproductive Effects: Penta has nants in penta are known carcino- been found in the semen of exposed gens.4 Agriculture Canada concludes Environmental Fate and Effects on workers and a significantly increased that the combined evidence from epi- Nontarget Organisms incidence of chromosomal aberrations demiological studies on human with Penta is a significant contaminant in exposed worker’s peripheral lym- mixed exposures to chlorophenols, di- of soil, surface water, and groundwa- phocytes (one of the cells found in oxins, or pesticides contaminated with ter especially around sawmills and blood) has been documented. Al- these chemicals suggest that occupa- wood preserving facilities.33,40 Re- though reproductive dysfunctions tional exposure to chlorophenols or searchers using a mathematical model have not been reported, these findings phenoxy herbicides increases the risk for partitioning of penta in the envi- suggest a high priority for future in- of three kinds of cancer: soft tissue ronment calculated that 96.5 percent vestigations of penta’s reproductive of penta is in soil, 2.5 percent in wa- effects.31 ter, 1 percent in air, and less than 1 Teratogenicity: EPA has concluded percent in suspended sediments and that penta and possibly its hexachloro- organisms in aquatic environments.25 dibenzo-p-dioxin (HxCDD) contami- In a study of movement of penta nants cause birth defects and fetotoxic from treated wood posts that were in effects in test animals.32 Reported ad- “EPA has concluded direct contact with soil, 95 percent of verse effects in fetuses from penta ex- that penta and possibly the penta remained in the wood posts posure include distorted sex ratios, its hexachlorodibenzo- after 2.5 months. Most of the penta increased incidences of resorbed em- that moved into the soil remained in bryos, skeletal anomalies, subcutane- p-dioxin (HxCDD) the upper layer immediately surround- ous edema ( excessive fluid), reduced contaminants cause ing the posts.41 Penta can persist in survival, and reduced growth.7,29 Re- the soil from 14 days to 5 years de- ported no observable effect levels birth defects and pending on the soil microbes (NOELs) for teratogenicity range from fetotoxic effects in test present.32 Researchers in Finland 3 to 5.8 milligrams per kilogram (mg/ animals.” found no clear decrease of soil levels kg) per day for penta and .001 mg/kg of penta one year after a sawmill with per day for HxCDD.4,29,33 a wood preserving facility on site Mutagenicity: The majority of tests stopped using penta.42 A study of the in yeast, bacteria, or mammalian cells effect of penta on the soil ecosystem have reported penta not to be geneti- reported that levels of 20 ppm inhib- cally active. Questions have been ited activity of the microbes in soil raised as to the validity of this re- sarcoma, Hodgkin’s lymphoma, and and continued to inhibit activity over search since controls, doses, and sta- non-Hodgkin’s lymphoma.33 the 48 day period of the study.43 tistical data were not reported in ev- Other Health Effects: Exposure to Because penta can move from soil ery study.7 Other tests have indicated penta has also been associated with to surface and ground water, effects that penta, and tetrachlorophenol, can aplastic anemia, leukemia, and other of penta on aquatic environments are damage genes.4,33 Penta’s metabolite, blood disorders.36 People exposed to also of concern. Researchers at St. Olaf tetrachlorohydroquinone, has also penta have reported peripheral neur- College in Minnesota applied penta to been shown to damage genes.34 Addi- opathy and other problems related to outdoor experimental water channels tional testing of penta in mammalian nerve damage (neurotoxicity) that stocked with fish and other aquatic systems is necessary to determine may also be due to exposure to penta’s organisms at the aquatic criterion level whether penta is mutagenic. contaminants.37 Commercial grade for penta (48 micrograms per liter), Carcinogenicity: Based on studies penta has also been demonstrated to three times this level, and nine times that report negative results for carci- suppress the immune system in mice, this level. Their study found adverse nogenicity, researchers prior to 1988 an effect that may also be due to ecosystem effects at all levels tested sug-

4 JOURNAL OF PESTICIDE REFORM / VOL. 11, NO. 1 gesting that criteria levels set to be pro- rophenol exposure in sawmills. Am. Ind. Hyg. ing litter and animal products for tective of the environment were failing Assn. J. 46(1):34-38. polychlorophenol residues, Ontario, Canada, 44 10. Kleinman, G. et al. 1986. Industrial hygiene, 1978-1986. Draft Report. Ontario, Canada: Min- to do so. Researchers in British Co- chemical and biological assessments of ex- istry of Agriculture and Food. lumbia have found penta in the posures to a chlorinated phenolic sapstain 27. Ryan, J.J. et al. 1985. Chlorinated dibenzo-p- nearshore waters of the lower Fraser control agent. Am. Ind. Hyg. Assn. J. 47(12):731- dioxins and chlorinated dibenzofurans and River at levels which would be toxic to 741. pentachlorophenol in Canadian chicken and salmon species after 24 and 48 hours. 11. Jones, R.D. 1986. Absorption study of pen- pork samples. J. Agric. Food Chem. 33:1025- tachlorophenol in persons working with 1026. Additional studies in the area have found wood preservatives. Human Toxicology 5:189- 28. Frank, R. et al. 1985. Organochlorine and or- substantial bioconcentration of penta in 194. ganophosphorus insecticides and industrial tissues of starry flounder and Dolly 12. U.S. Environmental Protection Agency. 1984. pollutants in the milk supplies of Ontario— Varden trout. Agriculture Canada has Special Review Position Document 4. Wash- 1983. J. Food Production 48(6):499-504. ington, DC: Office of Pesticides and Toxic Sub- 29. Hayes, W.J. 1982. Pesticides studied in man. concluded that use of penta and other stances. Baltimore: Williams & Wilkins. pp. 473-478. chlorophenols pose a significant hazard 13. Horstman, S.W. et al. 1989. Penetration of pen- 30. Uhl, S. et al. 1986. Pharmacokinetics of penta- to fish and fisheries in Canada, particu- tachlorophenol and tetrachlorophenol chlorophenol in man. Arch. Toxicol. 58:182- larly in British Columbia.33 through human skin. J. Env. Sci. Health A 186. 24(3):229-242. 31. Schrag, S.D. and R.L. Dixon. 1985. Occupa- Summary 14. Fenske, R.A. et al. 1987. Assessment of der- tional exposures associated with male repro- mal exposure to chlorophenols in timber ductive dysfunctions. Ann. Rev. Pharmacol. As a result of over 50 years of use as mills. Am. Ind. Hyg. Assn. J. 48(2):143-147. Toxicol. 25:567-592. a pesticide, pentachlorophenol residues 15. Murphy, R.S. et al. 1983. Selected pesticide 32. U.S. Environmental Protection Agency. 1978. are ubiquitous in the environment and residues or metabolites in blood and urine Pentachlorophenol position document 1. Wash- in humans. Humans who are occupation- specimens from a general population survey. ington, DC.: Office of Pesticides and Toxic Sub- Env. Health. Perspect. 48:81-86. stances. ally exposed to penta, or who live in 16. Hill, R.H. et al. 1989. Residues of chlorinated 33. Agriculture Canada. 1987. Pentachlorophenol homes constructed from treated wood, phenols and phenoxy acid herbicides in the discussion document. Ottawa, Ontario: Pesti- have the highest amounts of penta in urine of Arkansas children. Arch. Env. Contam. cides Directorate. their bodies, but a large majority of Toxicol. 18:469-474. 34. Witte, I. et al. 1985. DNA-damaging properties people with no obvious exposure also 17. Ryan, J.E. et al. 1985. Chlorinated dibenzo-p- and cytotoxicity in human fibroblasts of dioxins and chlorinated dibenzofurans in Ca- tetrachlorohydroquinone, a pentachlorophe- have measurable residues. In addition nadian human adipose tissue. Chemosphere nol metabolite. Mutation Research 145:71-75. to its acute effects, exposure to penta is 14:697-706. 35. U.S. Environmental Protection Agency. 1990. known to cause cancer and birth defects 18. Noren, K. 1988. Changes in levels of organo- Identification and listing of hazardous waste; in laboratory animals, as well as chro- chlorine pesticides, polychlorinated biphe- Wood preserving. Federal Register nyls, dibenzo-p-dioxins and dibenzo-furans in 55(235):50450-50490. mosome abnormalities, blood disorders, human milk from Stockholm, 1972-1985. 36. Roberts, H.J. 1990. Pentachlorophenol-asso- and nerve damage in humans. Penta has Chemosphere 17(1):39-49. ciated aplastic anemia, red cell aplasia, leuke- contaminated soil, surface water, and 19. Dougherty, R. 1978. Human exposure to pen- mia and other blood disorders. J. Florida Med. groundwater and affected fish popula- tachlorophenol. In Rao, K.R. (ed.) Pentachlo- Assn. 77(2):86-90. tions. As of 1989, penta was banned in rophenol: chemistry, pharmacology, and envi- 37. O’Donoghue, J.L. (Ed.). 1985. Neurotoxicity ronmental toxicology, pp. 351-361. New York: of industrial and commercial chemicals. Vol. ten countries and severely restricted in Plenum Press. II. Boca Raton, Florida: CRC Press. pp. 140- nine.45 ■ 20. Heath, Clark et al. 1981 (September 21). Pen- 142. tachlorophenol wood preservative exposure in 38. Kerkvliet, N.I. et al. 1982. Immunotoxicity References residents of log home. Louisville, Kentucky. of pentachlorophenol (PCP): increased sus- 1. Cedar, F. 1984. Historical and current devel- Atlanta: Public Health Service, Center for En- ceptibility to tumor growth in adult mice opments of antisapstain chemical use. In Sym- vironmental Health, Chronic Diseases Divi- fed technical PCP-contaminated diets. Toxi- posium on Preservatives in the Wood Indus- sion. EPI-80-60-2. cology and Applied Pharmacology 62:55-64. try. Vancouver, Canada: University of British 21. Cline, R.E. et al. 1989. Pentachlorophenol mea- 39. Kerkvliet, N.I. et.al. 1982. Immunotoxicity of Columbia. surements in body fluids of people in log technical pentachlorophenol (PCP-T): de- 2. U.S. Environmental Protection Agency. 1984 homes and workplaces. Arch. Environ. Contam. pressed humoral immune responses to T-de- (November). Pentachlorophenol (non-wood Toxicol. 18:475-481. pendent and T-independent antigen stimula- Uses) Special Review position document 2/3. 22. Roberts, J.W. et al. 1989. Development and tion in PCP-T exposed mice. Fundamental and Washington, DC: Office of Pesticides and Toxic field testing of a high volume sampler for pes- Applied Toxicology 2:90-99. Substances, p. I-5, I-6. ticides and toxics in dust. Presented at the 40. Valo, R. et al. 1985. Chlorinated phenols and 3. Morgan, D.P. 1989. Recognition and Manage- Symposium on Total Exposure Assessment their derivatives in soil and ground water ment of Pesticide Poisonings. Washington, DC: Methodology in Las Vegas. Sponsored by U.S. around wood-preserving facilities in Finland. U.S. Environmental Protection Agency. p. 73. Environmental Protection Agency, Air and Wat. Sci. Tech. 17:1381-1384. 4. U.S. Environmental Protection Agency. 1987 Waste Management Assn., World Health Or- 41. Gile, J.D. et al. 1982. Fate and impact of wood (March). Pentachlorophenol health advisory. ganization, and American Industrial Hygiene preservatives in a terrestrial microcosm. J. Washington, DC: Office of Drinking Water. Assn. Agric. Food Chem. 30:295-301. 5. Van Strum, Carol and Paul Merrell. 1989. The 23. Krause, C. et al. 1987. Pentachlorophenol con- 42. Kitunen, V.H. et al. 1987. Contamination of politics of penta. Seattle, WA: Greenpeace. taining wood preservatives: analysis and soil around wood-preserving facilities by poly- 6. U.S. Environmental Protection Agency. 1990. evaluation. In Seifert et al. (eds.) Indoor Air 87 chlorinated aromatic compounds. Environ. Sci. Suspended, Cancelled, and Restricted Pesticides. Proceedings. Vol. I. pp. 220-224. Technol. 21:96-101. Washington, D.C.: Office of Pesticides and 24. Roberts, J.W. and D.E. Camann. 1989. Pilot 43. Zelles, L. et al. 1985. Side effects of some pes- Toxic Substances. study of a cotton glove press test for as- ticides on non-target soil microorganisms. 7. Williams, P.L. 1982. Pentachlorophenol, an sessing exposure to pesticides in house Environ. Sci. Health B 20(5):457-488. assessment of the occupational hazard. Am. dust. Bull. Environ. Contam. Toxicol. 43:717- 44. Zischke, J.A. et al. 1985. Effects of pentachlo- Ind. Hyg. Assn. J. 43:799-810. 724. rophenol on invertebrates and fish in outdoor 8. Embree, V. et al. 1984. Occupational expo- 25. Hattemer-Frey, H.A. and C.C. Travis. 1989. Pen- experimental channels. Aquatic Toxicology sure to chlorophenates: toxicology and res- tachlorophenol: environmental partitioning 7:37-58. piratory effects. Clinical Toxicology 22(4):317- and human exposure. Arch. Environ. Contam. 45. Pesticide Action Network. 1990. Dirty dozen 329. Toxicol. 18:482-489. pesticides fact sheets. San Francisco, CA: PAN 9. Kauppinen, T. and L. Lindroos. 1985. Chlo- 26. Frank, R. et al. 1987. Monitoring wood shav- North American Regional Center.

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