Pentachlorophenol

Full Profile

General Information

Pure pentachlorophenol is a white, crystalline, aromatic compound.^[2] Impure pentachlorophenol is dark gray to brown and exists as dust, beads, or flakes. It may also be referred to as PCP or ‘penta’.^[3] There are numerous other synonyms and product names; see HSDB for more information.^[4]

Combined exposures to polychlorophenols or their sodium salts have been classified by IARC as Group 2B, possibly carcinogenic to humans.^[3] There is sufficient animal evidence for the carcinogenicity of pentachlorophenol in particular; it caused adrenal tumours in mice.^[5] In humans, there are suggested links to non-Hodgkin lymphoma (NHL) and soft tissue sarcomas in those occupationally exposed.^[3] In particular, a recent Canadian study found strong dose-response relationships between pentachlorophenol exposure and NHL, multiple myeloma, and kidney cancer.^[6]

Additionally, acute exposure to pentachlorophenol can cause fever and respiratory distress.^[2] Damage to the liver and immune system as well as reproductive and developmental effects have been observed in humans exposed to high levels of pentachlorophenol over long periods of time.^[2] Impurities in the PCP, however, such as dioxins and furans at parts per million levels, may also contribute to these effects.^[2]

Pentachlorophenol has been ranked by CAREX Canada for both the occupational and environmental settings as Group A (immediate high priority). Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.

Regulations and Guidelines

Occupational Exposure Limits (OEL)

Canadian Jurisdictions	OEL (mg/m3)
Canada Labour Code	0.5 [sk]
BC, AB, MB, ON, QC, NL, PE, NB, NS	0.5 [sk]
SK, YT, NT, NU	0.5 [sk] 1.5 [stel]
Other Jurisdiction	OEL (mg/m3)
ACGIH 2011 TLV	0.5 [sk]

Canadian Environmental Guidelines

Jurisdiction	Limit	Year
Canadian Drinking Water Guidelines	0.6 [AO < 0.03]	2005[7]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL – high priority substance with intermediate potential for exposure	2006[8]
Agreement Respecting the Great Lakes Basin Ecosystem	Tier II Substance	2002[10]

Main Uses

Pentachlorophenol and its sodium salt are primarily used as a fungicide for industrial wood preservation. It is used for utility poles, railroad ties, foundation pilings, timbers in highway construction, construction timbers and poles, bridge timbers & ties, and fence posts.^[2]

PCP can be applied to wood via pressure-treating or by thermal impregnation, where PCP is applied by spraying, dipping, brushing or soaking the wood.^[12]

Pentachlorophenol was registered for public use by the United States EPA until 1984. Since then it has been a restricted pesticide in the US, available only to certified applicators.^[2] Pentachlorophenol was formerly used in agriculture as an herbicide, defoliant, bactericide and molluscicide.^[5]

PCP may also have limited use in leather tanning, where it is used as a biocide. Current information on its use in this industry was not located.

Canadian Production and Trade

According to a 1995 report, pentachlorophenol has not been produced in Canada since the early 1980s.^[25]

In 2000, between 100 and 1,000 tonnes of pentachlorophenol (concentration >1%) were imported into Canada for use as a wood preservative.^[26]

Production and Trade

Activity	Quantity	Year
Canadian Production	2,200 t in 1981 (last year produced)	1997 (forecasted)[25]
Domestic Demand	1,100 t	1997 (forecasted)[25]
Export: N/A	None	2010[21]
Import: Mainly from Mexico, US	1,997 t of ‘pentachlorophenol ISO’	2010[21]

Occupational Exposures

Occupational exposure occurs via dermal contact with the compound or with treated wood products, or via inhalation of contaminated workplace air (i.e. during production or use of pentachlorophenol).^[2,3] Dermal contact is the most important route of exposure; one study found that it accounted for 95% of total worker exposure in sawmills.^[27]

The highest potential for occupational exposure in Canada is currently in the wood manufacture and preservation industry. Exposure can occur during application and handling of treated products.^[2,28]

Environmental Exposures

The general population is most likely to be exposed to pentachlorophenol in the vicinity of hazardous waste sites. This can occur via inhalation, ingestion of contaminated groundwater or food, or dermal contact with soils.^[2] In older homes that contain pentachlorophenol-treated wood, occupants can be exposed to low levels of pentachlorophenol in indoor air, or via dermal exposure from touching treated wood.^[2]

People who work or live near a wood treatment facility or where production of utility poles, railroad ties, or wharf pilings occurs may be exposed to pentachlorophenol.^[2]

Pentachlorphenol was not reportable to the National Pollutant Release Inventory^[31] or the US Household Products Database.^[32]

Sources

1. Wikimedia Commons, Photo: Pentachlorophenol
2. ATSDR Toxicological Profile for Pentachlorophenol (2001)
3. IARC monograph, Volume 71, 1999 (section on polychlorophenols) (PDF)
4. Hazardous Substances Data Bank (Search term: ‘pentachlorphenol’)
5. IARC Monograph Summary, Vol. 53, 1991 (PDF)
6. Demers, P., Davies, HW., et al (2006) ‘Cancer and occupational exposure to pentachlorophenol and tetrachlorophenol (Canada)’ Cancer Causes and Control Vol. 17, No. 7, pp. 749-758
7. Canadian Drinking Water Guidelines (2010)
8. Health Canada’s Prioritization of the DSL (2006)
9. CEPA List of Toxic Substances (1999)
10. Environment Canada (2002), Report: The Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem (PDF)
11. Environment Canada: Draft characterization (for 6 pesticides, including pentachlorophenol)
12. Fisher, B., (1991), ‘Pentachlorophenol: Toxicology and Environmental Fate,’ Journal of Pesticide Reform, Vol. 11, No. 1, pp. 2-5 (PDF)
13. EPA Fact Sheet for the Pentachlorophenol risk assessment (2004)
14. Stephens RW, Brudermann GE, Konasweich DE. Summary of the Results of Environment Canada’s Assessment 2000 Program for the Canadian Wood Preservation Industry (2001) (PDF)
15. Environment Canada, NPRI Toolbox: Pentachlorophenol Wood Preservation Facilities, Process Description (2009)
16. Pest Management Regulatory Agency, Re-Evaluation Note Re-evaluation Note: Update on the Re-evaluation of the Heavy Duty Wood Preservatives Creosote, Pentachlorophenol and CCA (2008)
17. Pesticides Management Regulatory Agency (PMRA) List of Registered Pesticides (Canada)
18. Survey of Pesticide Use in British Columbia: 1999 (April 2001). Prepared by EKON Environment Limited, Surrey, BC, CANADA. [EC/GB-01-032], for Environment Canada and Ministry of Environment, Lands, and Parks (PDF)
19. BC Ministry of the Environment, Survey of Pesticide Use in BC (2003) (PDF)
20. Industry Canada (2006), Special Report; Lumber and Value-Added Wood Products (PDF)
21. TradeMap (Free subscription required)
22. Health Canada (2011) Cosmetic Ingredient Hotlist
23. Health Canada (2006) Food Additives Permitted for Use in Canada
24. Exposure Guidelines for Residential Indoor Air Quality (1987) (PDF)
25. CPI Product Profiles, Camford Information Services: Pentachlorophenol (PCP) (1995)
26. Draft Entry Characterization for Public Comment, Canadian Environmental Protection Act, 1999 (2006) (PDF)
27. Fenske RA, Horstman SW, Bentley RK (1987) Assessment of dermal exposure to chlorophenols in timber mills. Appl Ind Hyg. 2:143–147
28. CCOHS, Occupational Groups Associated with Carcinogen Exposure (2008)
29. CEPA List of Toxic Substances (1999)
30. Government of Canada (2010) Chemicals Management Plan – List of all Challenge Substances
31. The National Pollutant Release Inventory
32. Household Products Database (US)

Other Resources

1. ATSDR ToxFAQs Sheet for Pentachlorophenol