Pentachlorophenol Profile

PESTICIDES  KNOWN CARCINOGEN (IARC 1)

CAS No. 87-86-5
IARC Monograph Vol. 71, 1999 (Group 2B)
IARC Monograph Vol. 117, 2016 (Group 1)

Pentachlorophenol Profile

QUICK SUMMARY

  • A pesticide used in industrial wood preservation
  • Associated cancer: Non-Hodgkin lymphoma
  • Most important route of exposure: Skin contact
  • Uses: Primarily used as a fungicide on utility poles; also registered for use railroad ties, sawn products, plywood, and pilings
  • Occupational exposures: Approx. 4,300 workers are exposed at work, primarily in the farming sector where pentachlorophenol is used on fence posts to prevent rot
  • Environmental exposures: Via living near hazardous waste sites and older homes that contain pentachlorophenol-treated wood
  • Fast fact: Pentachlorophenol is targeted by international environmental agreements (ex. Stockholm Convention) for elimination, except its use on utility poles and cross-arms.

General Information

Pure pentachlorophenol is a white crystalline, aromatic compound.[1] Impure pentachlorophenol is dark gray to brown in colour and exists as dust, beads, or flakes. It may also be referred to as PCP or penta.[1] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[2]

In 2016, the International Agency for Research on Cancer (IARC) classified pentachlorophenol as Group 1, carcinogenic to humans, based on sufficient evidence that it causes non-Hodgkin lymphoma (NHL) in humans.[3] Exposure to PCP was associated with an increased risk of NHL in all of the available epidemiological studies, including in Canadian sawmill workers[4] and US pesticide manufacturing workers.[3] Several studies also reported an increased risk of multiple myeloma, a subtype of NHL.[3]

Additionally, acute exposure to pentachlorophenol can cause fever and respiratory distress.[1] High levels of exposure to pentachlorophenol over long periods of time can damage the liver and immune system, and cause reproductive and developmental effects.[1] Impurities in the pentachlorophenol, such as dioxins and furans at parts per million levels, may contribute to these 
effects.[1]

Regulations and Guidelines

Occupational Exposure Limits (OEL)[5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]

Canadian Jurisdictions OEL (mg/m3)
Canada Labour Code 0.5 [sk, IFV]
1 [stel, sk, IFV]
MB, ON, NL, PE, NS 0.5 [sk, IFV]
1 [stel, sk, IFV]
BC, AB, NB 0.5 [sk]
QC 0.5 [sk; em]
SK, YT, NT, NU 0.5 [sk]
1.5 [sk, stel]
Other Jurisdiction OEL (mg/m3)
ACGIH 2018 TLV 0.5 [sk, IFV]
1 [stel, sk, IFV]
mg/m3 = milligrams per cubic meter
sk = easily absorbed through the skin
stel = short term exposure limit (15 min. maximum)
IFV = inhalable fraction and vapour
em = exposure must be reduced to the minimum
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

Canadian Environmental Guidelines

Jurisdiction Limit Year
Ontario Ambient Air Quality Criteria 24 hour: 20 µg/m3 2016[20]
Alberta Ambient Air Quality Objectives & Guidelines 1 hour: 5.0 µg/m3 2017[21]
Annual Average: 0.5 µg/m3 2013[21]
Canadian and Ontario Drinking Water Guidelines MAC: 0.06 mg/L [AO < 0.03] 2017[22,23]
Quebec’s Regulation respecting the quality of drinking water, CQLR c Q-2, r 40 MAC: 0.042 mg/L 2016[24]
BC’s Contaminated Sites Regulation, BC Reg 375/96 Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 90 μg/g
Urban park and high density residential sites: 200 μg/g
Commercial sites: 550 μg/g
Industrial sites: 900 μg/gDrinking water:60 µg/L
2017[25]
MAC = maximum acceptable concentration
AO = aesthetic objective
µg/m3 = micrograms per cubic meter
μg/g = micrograms per gram

Pentachlorophenol was not included in other Canadian environmental guidelines reviewed.[26,27,28,29]

Canadian Agencies/Organizations

Agency Designation/Position Year
Health Canada DSL – high priority substance with intermediate potential for exposure 2006[30]
Stockholm Convention on POPs Annex A: Elimination, with exemptions for use in utility poles and cross-arms 2014[31]
Agreement Respecting the Great Lakes Basin Ecosystem Tier II Substance 2002[32]
National Classification System for Contaminated Sites Rank: “High Hazard” 2008[33]
Although pentachlorophenol is persistent and inherently toxic to humans and other organisms, it is not included in the Canadian Environmental Protection Act because it falls under the Pest Control Products Act. Its management is the responsibility of the Pesticides Management Regulatory Agency.[34]
DSL = domestic substances list
POPs = persistent organic pollutants

Pentachlorophenol was not included in other Canadian government chemical listings reviewed.[35,36,37]

Main Uses

In 2011, the Pest Management Regulatory Agency (PMRA) re-evaluated pentachlorophenol and approved its registration as a fungicide for industrial wood preservation. Pentachlorophenol is registered for use on utility poles, railroad ties, sawn products, plywood, and pilings.[34] The primary use of PCP is on utility poles.[34] In 2014, PCP was added to the List of Persistent Organic Pollutants (POPs) under the Stockholm Convention, with an ultimate goal of elimination except for use on utility poles and crossarms.[38] The effects of this new designation on PCP use in Canada is not known, but is likely to be minimal since PCP is primarily used on utility poles. Pentachlorophenol is currently registered for use by the PMRA in three formulations.[39]

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.[40]

Pentachlorophenol was formerly used in agriculture as an herbicide, defoliant, bactericide, and molluscicide.[41]

Canadian Production and Trade

According to a 1995 report, pentachlorophenol has not been produced in Canada since the early 1980s.[42]

In 2000, between 100 and 1,000 tonnes of PCP (concentration >1%) were imported into Canada for use as a wood preservative.[43] TradeMap lists pentachlorophenol export and import data; however, reporting for pesticides is not standardized and the data is incomplete.[44]

Production and Trade

Activity Quantity Year
Canadian Production 2,200 t in 1981 (last year produced) 1997 (forecasted)[42]
Domestic Demand 1,100 t 1997 (forecasted)[42]
t = tonne

Environmental Exposures Overview

Pentachlorophenol can enter the environment (in air, water, and soil) via evaporation from treated woods, industrial spills, and disposal at hazardous waste sites. The general population is most likely exposed to PCP in the vicinity of hazardous waste sites, as well as in older homes that may contain PCP-treated wood.[1] Therefore, low level exposure to PCP may occur by ingesting contaminated indoor or outdoor air, ground water, and food, or via dermal contact with contaminated wood and soil.[1]

People who work or live near a wood treatment facility or where utility poles, railroad ties, or wharf pilings are produced may be exposed to PCP.[1]

Data on Canadian environmental PCP concentration and exposure are limited. Based on the very low data quality available, CAREX Canada developed environmental exposure estimates to pentachlorophenol through various exposure pathways. CAREX Canada’s environmental exposure estimates suggest that PCP concentrations in outdoor air, indoor air, indoor dust, drinking water, and food or beverages do not result in an increased risk of cancer in Canada (very low data quality).

Pentachlorophenol was one of the substances selected for Cycle 2 of the Canadian Health Measures Survey (CHMS), an ongoing joint project of Statistics Canada and Health Canada to establish the current level of exposure to environmental contaminants.[45] Biomonitoring data from the CHMS on Canadians was released in 2013 in the Second Report on Human Biomonitoring of Environmental Chemicals in Canada.[45]

Pentachlorophenol was not reportable to the National Pollutant Release Inventory,[46] nor was it noted in any products in the US Household Products Database.[47]

Occupational Exposures Overview

Occupational exposure to pentachlorophenol occurs via dermal contact with the compound while treating wood products, or by inhaling contaminated workplace air (i.e. during production or use of PCP).[1,3] One study found that dermal contact accounted for 95% of total worker exposure in sawmills.[48]

CAREX Canada estimates that approximately 4,300 Canadians are exposed to PCP in their workplaces. The largest industrial groups exposed are farming, electrical power generation and transmission, and wood preservation facilities, respectively. The largest occupational groups exposed to pentachlorophenol are farmers and farm workers, followed by electrical power line and cable workers.

For more information, see the occupational exposure estimate for PCP.

Sources

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Pentachlorophenol (2001)
2. US National Library of Medicine. Hazardous Substances Data Bank (Search term: ‘Pentachlorphenol’)
3. International Agency for Research on Cancer (IARC) Working Group. IARC Monographs, Volume 117: Pentachlorophenol and Some Related Compounds (2019)
4. Demers PA, Davies HW, Friesen MC, Hertzman C, Ostry A, Hershler R, Teschke K. “Cancer and occupational exposure to pentachlorophenol and tetrachlorophenol (Canada)” Cancer Causes Control 2006;17(7):749-758.
10. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2012)
11. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2016) (PDF)
13. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
15. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1 (2013) (PDF)
17. Government of Saskatchewan. The Occupational Health and Safety Regulations, 1996 (2016) (PDF)
18. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2012) (PDF)
19. Occupational Safety and Health Administration (OSHA). Annotated PELs (2018)
20. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2016)
21. Alberta Environment and Parks. Ambient Air Quality Objectives (2017)
23. The Canadian Legal Information Institute (CanLII). Ontario Drinking Water Quality Standards, O Reg 169/03 (2017)
24. The Canadian Legal Information Institute (CanLII). Regulation respecting the quality of drinking water, CQLR c Q-2, r 40 (2014)
25. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2017)
26. Health Canada. Cosmetic Ingredient Hotlist (2014)
30. Health Canada. Prioritization of the DSL (2006)
33. Canadian Council of Ministers of the Environment (CCME). National Classification System for Contaminated Sites (2008) (PDF)
35. Canadian Centre for Occupational Health and Safety (CCOHS). Occupational Groups Associated with Carcinogen Exposure(2008)
37. Health Canada. PMRA List of Formulants (2010) (PDF)
39. Health Canada. Search Product Label
40. Fischer B. “Pentachlorophenol: Toxicology and Environmental Fate” Journal of Pesticide Reform 1991;11(1):2-5.
41. International Agency for Research on Cancer (IARC). Monograph summary, Volume 53 (1991) (PDF)
42. Camford Information Services. CPI Product Profiles: Pentachlorophenol (PCP) (1995)
44. International Trade Centre. TradeMap (Free subscription required)
46. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘Pentachlorophenol’)
47. US Household Products Database. Household Products (Search term: ‘Pentachlorophenol’)
48. Fenske RA, Horstman SW, Bentley RK. “Assessment of dermal exposure to chlorophenols in timber mills.” Applied Industrial Hygiene 1987;2:143-147.

Other Resources

  1. Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQs Sheet for Pentachlorophenol (2001) (PDF)

Subscribe to our newsletters

The CAREX Canada team offers two regular newsletters: the biannual e-Bulletin summarizing information on upcoming webinars, new publications, and updates to estimates and tools; and the monthly Carcinogens in the News, a digest of media articles, government reports, and academic literature related to the carcinogens we’ve classified as important for surveillance in Canada. Sign up for one or both of these newsletters below.

CAREX Canada

Faculty of Health Sciences

Simon Fraser University
Harbour Centre Campus
2602 - 515 West Hastings St
Vancouver, BC  V6B 5K3
CANADA

© 2019 CAREX Canada