Pure pentachlorophenol is a white, crystalline, aromatic compound. Impure pentachlorophenol is dark gray to brown and exists as dust, beads, or flakes. It may also be referred to as PCP or ‘penta’. There are numerous other synonyms and product names; see HSDB for more information.
In 2016, IARC classified PCP as Group 1, carcinogenic to humans, based on sufficient evidence that it causes non-Hodgkin lymphoma (NHL) in humans. Exposure to PCP was associated with an increased risk of NHL in all of the available epidemiological studies. For instance, an increased incidence of NHL was observed in Canadian sawmill workers and US pesticide manufacturing workers exposed to PCP. Several studies also reported an increased risk of multiple myeloma, a subtype of NHL.
Additionally, acute exposure to pentachlorophenol can cause fever and respiratory distress. 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. Impurities in the PCP, however, such as dioxins and furans at parts per million levels, may also contribute to these effects.
stel = short term exposure limit (15 min. maximum)
Canadian Environmental Guidelines
Ontario Ambient Air Quality Criteria
24 hour 20 µg/m3
Alberta Ambient Air Quality Objectives & Guidelines
1 hour 5.0 µg/m3
Annual Average 0.5 µg/m3
Canadian Drinking Water Guidelines
0.6 MAC [AO < 0.03]
MAC = maximum acceptable concentration
AO = aesthetic objective
µg/m3 = micrograms per cubic meter
Pentachlorophenol was not included in other Canadian government environmental guidelines reviewed.[18-20]
DSL – high priority substance with intermediate potential for exposure
Stockholm Convention on POPs
Annex A: Elimination, with exemptions for use in utility poles and cross-arms
Agreement Respecting the Great Lakes Basin Ecosystem
Tier II Substance
Pentachlorophenol was not included in other Canadian government chemical listings reviewed.[24,25] Although pentachlorophenol is persistent and inherently toxic to humans and other organisms, it is not included in CEPA because it falls under the Pest Control Products Act. Its management is the responsibility of the Pesticides Management Regulatory Agency.
In 2011, the Pest Management Regulatory Agency (PMRA) re-evaluated PCP and approved its registration as a fungicide for industrial wood preservation. PCP is registered for use on poles, railroad ties, sawn products, plywood, and pilings, but is primarily used on utility poles. In 2014, PCP was added to the List of POPs under the Stockholm Convention, with an ultimate goal of elimination except for PCP’s use on utility poles and cross-arms. The effect of this new designation on PCP’s use in Canada is not known, but is likely to be minimal since PCP is primarily used on utility poles.
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.
Formerly, pentachlorophenol was used in agriculture as an herbicide, defoliant, bactericide and molluscicide.
Canadian Production and Trade
According to a 1995 report, pentachlorophenol has not been produced in Canada since the early 1980s.
In 2000, between 100 and 1,000 tonnes of pentachlorophenol (concentration >1%) were imported into Canada for use as a wood preservative.
Production and Trade
2,200 t in 1981 (last year produced)
Import: Mainly from Mexico, US
1,997 t of ‘pentachlorophenol ISO’
t = tonne
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.
CAREX Canada estimates that approximately 4,300 Canadians are exposed to pentachlorophenol 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.
PCP 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 to be exposed to pentachlorophenol in the vicinity of hazardous waste sites, as well as in older homes that may contain pentachlorophenol-treated wood. Therefore, low level exposure to PCP may occur through ingestion of contaminated indoor or outdoor air, ground water, food, or via dermal contact with contaminated wood and soil.
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.
CAREX Canada’s environmental exposure estimates suggest that pentachlorophenol concentrations in outdoor air, indoor air, indoor dust*, drinking water, and food or beverages may not be a significant source of excess cancer risk in Canada (very low data quality).
Pentachlorophenol is 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. Biomonitoring data from the CHMS on Canadians was released in 2013 in the Second Report on Human Biomonitoring of Environmental Chemicals in Canada.
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 PCP through various exposure pathways.
Pentachlorphenol was not reportable to the National Pollutant Release Inventory or the US Household Products Database.
Our team has performed a detailed scan of exposure control resources and assembled a compilation of key publications and resources. These are organized by type of exposure (environmental or occupational) and by specificity (general or carcinogen-specific). Please visit our Exposures Reduction Resources page to view.
We also recommend exploring the Prevention Policies Directory, a freely-accessible online tool offering information on policies related to cancer and chronic disease prevention. Providing summaries of the policies and direct access to the policy documents, the Directory allows users to search by carcinogen, risk factor, jurisdiction, geographical location, and document type. Click hereTo learn more about policies specific to PCP in the Directory. For questions about this resource, please contact a member of the Prevention Team at the Canadian Partnership Against Cancer at firstname.lastname@example.org.