INDUSTRIAL CHEMICALS – PROBABLE CARCINOGEN (IARC 2A)
“Creosotes” are complex and variable mixtures made from distilled coal. They are composed of more than three hundred compounds, though only a limited number of those compounds are present in amounts greater than 1%. Creosotes derived from distilling coal are often referred to as coal-tar creosotes and are used to protect wood from fungi, insects, and marine organisms.
Wood creosotes are a separate group of chemicals derived from the resin of creosote bush leaves, or from beechwood leaves. Wood creosotes are not considered in this profile, as they are not chemically related to coal-based creosotes. CAREX Canada has evaluated several other substances related to creosotes, including Polycyclic Aromatic Hydrocarbons (PAHs) and Coal-tar & Coal-tar Pitches; please consult these profiles for further information.
Coal-tar creosote is primarily composed of PAHs (up to 90%), with small amounts of phenolics and nitrogen-, sulphur-, and oxygen-containing heterocyclic compounds.
Creosotes derived from coal-tars have been classified by the International Agency for Research on Cancer (IARC) as Group 2A, probably carcinogenic to humans, based on sufficient evidence in animals and limited evidence in humans.[4,5] Creosotes are skin and lung carcinogens in mice. Human evidence suggests a link between creosote exposure and skin cancer (especially scrotal), but this is based on only a few small studies.
Exposure to creosotes can irritate the skin and respiratory tract.
Regulations and Guidelines
No occupational exposure limits for creosotes were found in the American Conference of Governmental Industrial Hygienists (ACGIH) or Canadian Occupational Exposure Limit (OEL) guidelines.[6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] Nunavut and Saskatchewan list creosotes as designated substances.[6,7]
Canadian environmental guidelines
|Cosmetic Ingredients Hotlist||Not Permitted||2004|
|Health Canada||DSL – high priority substance
with lowest potential for exposure
|CEPA||Schedule 1, paragraph ‘a’||1999|
|National Classification System
for Contaminated Sites
|Rank = “Medium hazard”||2008|
|Environment Canada’s National
Pollutant Release Inventory
|Reportable to NPRI if released at quantities greater
than 1 tonne of 10-tonne total VOC air release.
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act
Creosote was not included in other Canadian government guidelines, standards, or chemical listings reviewed.
Coal-tar creosotes are primarily used as heavy-duty wood preservatives on railroad ties, fence posts, marine pilings, utility poles, and outdoor lumber. The service life of creosote-treated wood products is estimated at 40 to 50 years. There are 9 pesticide products registered for use in Canada as a wood preservative or in the manufacture of wood preservatives.
Canadian Production and Trade
Canada is the second-largest producer of treated wood (second to the USA and equal to the UK). In 1999, Canada produced nearly 3.5 million cubic meters of treated wood; about 6% of the wood was treated with creosotes. A 2006 analysis of the treated wood industry in Canada predicted that production will remain stable for the foreseeable future. Approximately 13% of domestically consumed wood products are treated, but only 4% of the production total is treated because most wood exports are untreated.
In 2003, creosote was the most commonly used pesticide in British Columbia. About 2,200 tonnes of creosotes were sold in BC that year, constituting 47% of all pesticides used. Creosote use was not reported in the 2010 or 2017 reports.[31,32]
From 2007 to 2008, Ontario used 3.6 million cubic metres of creosote-treated wood containing 179,891 tonnes of creosote. A total of 89% of the treated wood was used for railway ties, 8% for treated utility poles, and 3% for highway structures.
In 2020, there were three creosote treatment plants across Canada in Quebec and British Columbia. There have been no operating wood treatment plants in Ontario since the Thunder Bay Plant closure in 2002.[26,33]
Production and trade
|Export||34,315 t of “creosote oils”||2021|
|Import||454 t of “creosote oils”||2021|
t = tonne
Environmental Exposures Overview
Sources of environmental exposure include drinking contaminated water, contacting creosote-treated scrap lumber, using creosote treated materials, and living in houses built with creosote treated wood.
In Canada, waste materials containing creosotes arise from two sources: creosote waste products (i.e. railway ties), which accounts for 71% of waste materials by weight; and creosote-contaminated sites (i.e. where creosote is found in soils or groundwater), which accounts for 29% of waste material.
By volume, railway ties are the largest creosote waste product in Canada. Every year the major railways decommission 4.5 million ties which contain an estimated 20,000 tonnes of creosote. Approximately 90% of all railway ties are reused, leaving approximately 2,000 tonnes of waste creosote per year.
A report from 2008 breaks down Ontario’s pattern of creosote disposal methods as follows: 66% sent to the US for incineration (railway ties only), 26% sent to landfills, 8% sent to reuse/recycling. Open burning and sale to third parties is not practiced. Creosote waste products other than railway ties are generated from utility poles, highway timbers, agricultural fence posts, other minor agricultural structures, and possibly wood block floors.
Occupational Exposures Overview
The most important routes of occupational exposure to creosotes are inhalation and dermal.
CAREX Canada estimates that approximately 4,100 Canadians are exposed to creosotes in their workplace. The primary industrial groups exposed are within the sawmill and wood preservation industry and electric power generation (transmission and distribution). Other important exposed groups include utility system construction and rail transportation. The occupational groups with the largest numbers of workers exposed include: construction trades helpers and labourers, electrical power line and cable workers, labourers in wood, pulp and paper processing, and railway yard and track maintenance workers. Other occupations that may also be exposed include fence and bridge construction workers and site remediation workers.
According to the Burden of Occupational Cancer in Canada project, occupational exposure to creosotes leads to possibly 95 non-melanoma skin cancers each year in Canada, based on past exposures (1961-2001). [37,38] This amounts to 0.1% of all non-melanoma skin cancers diagnosed annually. Most cancers related to creosotes occur among workers in the manufacturing, transportation & warehousing, and construction sectors.
For more information, see the occupational exposure estimate for creosotes.
- Wood Preservation Canada (WPC). WPC (formerly the Canadian Institute of Treated Wood)
- Canadian Wood Preservation Association (CWPA). CWPA
- The Canadian Standards Association (CSA). CSA
- J.T. Fyles Natural Resources Library. Natural Resources Library (Search term: ‘Creosote’)
- International Programme on Chemical Safety (IPCS). Concise International Chemical Assessment Document (CICAD) 62: Coal Tar Creosote
- Government of Canada. Recommendations for the Design and Operations of Wood Preservation Facilities (2013) (PDF)
- US Environmental Protection Agency (EPA). Preliminary Risk Assessment for Creosote (2003)
- Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQs Sheet for Creosote (2002) (PDF)
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