Coal Tar and Coal-Tar Pitches Profile

INDUSTRIAL CHEMICALS  KNOWN CARCINOGEN (IARC 1)

CAS No. 8007-45-2 (Coal tar)
CAS No. 65996-93-2 (Coal-tar pitches)
IARC Monograph Vol. 35, Suppl. 7, 1987 (Group 1)
IARC Monograph Vol. 100F, 2012 (Group 1)

Coal Tar and Coal-Tar Pitches Profile

QUICK SUMMARY

  • A by-product of coke or gas production from carbonized coal
  • Associated cancers: Skin and lung cancers
  • Most important route of exposure: Inhalation, skin contact
  • Uses: Industrial and consumer products such as creosote and coal-tar pitch, furnace fuel in the steel industry, pharmaceuticals, roofing, surface coatings, and aluminum smelting electrodes
  • Occupational exposures: Approx. 7,600 Canadians are exposed at work, primarily those in aluminum production and processing, and foundation, structure, and building contractors
  • Environmental exposures: Via products used to treat skin disorders (ex. psoriasis, dandruff) and living near production sites
  • Fast fact: Coal tars and coal-tar pitches are complex mixtures containing over 400 identified compounds including hydrocarbons, phenols, and heterocyclic compounds.

General Information

Coal tar is produced as a byproduct when coal is carbonized to make coke or gas. When distilled, coal tar produces creosotes as a product and coal-tar pitch as a residue.[1] Coal tars are viscous and slightly soluble in water, while coal-tar pitches can be semi-solid to solid.[2] Coal tars and coal-tar pitches are complex mixtures containing over 400 identified substances including hydrocarbons, phenols, and heterocyclic compounds.[1] They have many uses industrially and in consumer products. Coal-tar pitch volatiles (CTPVs), which contain varying concentrations of polycyclic aromatic hydrocarbons (PAHs), are released when coal-tar pitch is heated.[3] Creosotes are oily liquids used extensively in wood preservation; please consult the separate Creosotes profile for more information on this substance. Other substances related to coal tar and coal-tar pitches that are also considered by CAREX Canada include BitumensBenzene, and Naphthalene.

Coal tar and coal-tar pitches have been classified by the International Agency for Research on Cancer (IARC) as Group 1, carcinogenic to humans, with an established link to skin cancer and scrotal cancer.[4] The 2012 IARC review of Group 1 substances reaffirmed this classification,[5] citing sufficient evidence in humans for a causal relationship between exposure to coal-tar pitch in paving and roofing and lung cancer. This review also cited limited evidence in humans for bladder cancer.[5] Coke production and coal gasification were also classified as Group 1, based on lung cancer outcomes.[5] There is additional evidence linking coal tar and coal-tar pitches to kidney, bladder, and digestive tract cancers, and leukemia.[1]

Additional adverse health outcomes of coal tar and coal-tar pitches include skin, eye, and respiratory tract irritation.[3]

Regulations and Guidelines

Occupational Exposure Limits (OEL) for coal-tar pitch volatiles (as benzene soluble aerosol) [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

Canadian Jurisdictions OEL (mg/m3)
Canada Labour Code 0.2
AB, BC, MB, NB, NL, NS, ON, PE 0.2
QC 0.2 [em]
SK, NT, NU 0.2
0.6 [stel]
YT none
Other Jurisdiction OEL (mg/m3)
ACGIH 2018 TLV 0.2
mg/m3 = milligrams per cubic meter
em = exposure must be reduced to the minimum
stel = short term exposure limit (15 min. maximum)
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

Canadian Environmental Guidelines

Jurisdiction Limit Year
Cosmetics Hotlist ‘Coal tar dye’ – Permitted, with conditions
‘Coal tars (crude and refined)’ – Not permitted
2014[21]
Ontario Ambient Air Quality Criteria Coal tar pitch volatiles – soluble fraction
24-hour: 1 µg/m3
Annual:0.2µg/m3
2016[22]
µg/m3 = micrograms per cubic meter

Coal tar and coal-tar pitches were not included in other Canadian government environmental guidelines reviewed.[23,24,25,26,27,28,29,30]

Canadian Agencies/Organizations

Agency Designation/Position Year
Health Canada DSL – high priority substance with greatest potential for exposure 2006[31]
CEPA Entry for ‘PAHs’ only 1999[32]
National Classification System for Contaminated Sites Rank = “High hazard”, confirmed human carcinogen 2008[33]
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act

Coal tar was not included in other Canadian government chemical listings reviewed.[34,35,36,37]

Main Uses

The majority of coal tar is distilled to produce refined products, including creosote, coal-tar pitch, crude naphthalene, and anthracene oils.[1] Because of its high availability and heating value, some crude coal tar is used as fuel for blast furnaces in the steel industry.[5] Coal tar also has a long history of use in pharmaceutical products to treat skin conditions, including eczema, psoriasis, and dandruff. It is also used in denatured alcohol.[5]

Coal-tar pitches have primarily been used as binders in aluminum smelting electrodes.[3] They are also used in roofing materials, surface coatings and pavement sealants, as well as for pitch coke production.[3,38]

Canadian Production and Trade

In 2015, Canadian mines produced 62 million tonnes of coal, a 10% decrease from 2014. Most of the decline is attributable to a weak global demand for metallurgical coal.[39]

The amount of coal tar and coal-tar pitch produced from coal was not identified. Because coal tar is a byproduct, metallurgical use – i.e. coking for the steel industry – was the second largest use.[40] Ontario is the main provincial consumer of coal for coke 
production.[40]

Production and Trade

Activity Quantity Year
Domestic coal consumption 38.8 Mt 2016[41]
Export: 137,678 t of ‘oils and other products of the distillation of high temperature coal’ 2015[42]
Export: 101,193 t of ‘pitch and pitch coke’ 2015[42]
Import: 105,997 t of ‘oils and other products of distillation of high temperature coal’ tar’ 2015[42]
Import: 34 t of ‘pitch and pitch coke’ 2015[42]
t = tonne
Mt = megatonne

Environmental Exposures Overview

Inhalation, dermal contact, and ingestion are all potential routes of exposure for the general public.[1]

Common exposure sources include pharmaceutical products (lotions and ointments) used to treat skin disorders such as psoriasis, and shampoos used for dandruff.[1] In Canada, anti-dandruff products are classified as drugs if they contain coal tar at concentrations of 0.5-10%.[43] Coal tar in these products are prepared by mixing coal tar with alcohol, polysorbate and washed sand, resulting in a filtered and diluted solution. Thus, the composition of coal tar in these products differs from industrial uses of coal tar.[38]

Coal tar-based pavement sealants, which are primarily used in residential driveways and small commercial or residential parking lots, are another potential source of exposure.[38] Levels of coal tar in soils and dusts adjacent to the sealed lots were higher compared to those adjacent to non-sealed lots.[38] Dermal exposure may occur when applying the sealant to the driveway.[38]

Living near factories or plants that use coal tar or coal-tar pitches is a potential source of exposure.[44] A total of 25 former coal tar/creosote production sites in Ontario were recently tested and had a persistent occurrence of subsurface coal tar.[2] Most of the sites had not been actively engaged in production for over 35 years.[2] In 1999, the city of Kingston, Ontario undertook a large clean up of its former coal gasification site which ran until the late 1950s. Large quantities of soil and groundwater contaminated with coal tar were removed to prevent further exposures to the public; not all of the contamination could be removed.[45]

Some components of coal tar and coal-tar pitch bioaccumulate in aquatic species.[3] In particular, polycyclic aromatic hydrocarbons (PAHs) accumulate to greater extents than the other components, with bioconcentration factors exceeding 5,000 for certain substances.[38]

Releases of coal tar and coal-tar pitches are not reportable to Environment Canada’s National Pollutant Release Inventory (NPRI).[46] Searches of a US consumer product database yielded the following results on current potential for exposure to coal tar and coal-tar pitches in Canada:

US Household Products Database

US Household Products 2015[47]
Search Term Quantity Product Type
‘Coal-tar pitch’ 5 Sealants (3), pet shampoo (2)
‘Refined coal-tar pitch’ 3 Driveway sealants (3)

Occupational Exposures Overview

Inhalation and dermal contact are the most important routes of occupational exposure.[2]

CAREX Canada estimates that approximately 7,600 Canadian workers are exposed to coal tar and coal-tar pitches in their workplace. Among Canadian industries, the largest exposed groups are aluminum production and processing; foundation, structure, and building contractors; and highway, street, and bridge construction. The largest exposed occupational groups are roofers and shinglers, followed by construction trades helpers and labourers, and machine operators in mineral and metal processing.

Other industries with potential for occupational exposure to coal tar and coal-tar pitch include those associated with coke production, coal gasification, steel foundries, and installation of electrical equipment.[1,2] Exposure may also occur when producing or using refractory bricks, paints, enamels, or coatings.[1]

For more information, see the occupational exposure estimate for coal tar and coal-tar pitches.

Sources

Photo: Flickr, MPCA Photos

1. National Toxicology Program (NTP). 14th Report on Carcinogens for Coal tar and Coal-tar Pitches (2016) (PDF)
2. US National Library of Medicine. Hazardous Substances Data Bank (Search term: ‘coal tar and coal-tar pitches’)
4. International Agency on Research for Cancer (IARC). Monograph summary, Volume 35, Supplement 7(1987) (PDF)
5. International Agency for Research on Cancer (IARC). Monograph summary, Volume 100, Part F (2011) (PDF)
11. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2012)
12. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2016) (PDF)
14. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
16. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1 (2013) (PDF)
18. Government of Saskatchewan. The Occupational Health and Safety Regulations, 1996 (2016) (PDF)
19. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2012) (PDF)
20. Occupational Safety and Health Administration (OSHA). Annotated PELs (2018)
21. Health Canada. Cosmetic Ingredient Hotlist (2014)
22. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2016)
26. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2017)
27. The Canadian Legal Information Institute (CanLII). Ontario Drinking Water Quality Standards, O Reg 169/03 (2017)
28. Canadian Legal Information Institute (CanLII). Regulation respecting the quality of drinking water, CQLR c Q-2, r 40 (2016)
30. Alberta Environment and Parks. Ambient Air Quality Objectives (2017)
31. Health Canada. Prioritization of the DSL (2006)
32. Environment and Climate Change Canada. CEPA List of Toxic Substances (1999)
33. Canadian Council of Ministers of the Environment (CCME). National Classification System for Contaminated Site (2008) (PDF)
39. Natural Resources Canada. Minerals and Metals Factbook (2016) (PDF)
40. Natural Resources Canada. Minerals and Metals Fact Book – 2015 (2016) (PDF)
42. International Trade Centre. TradeMap (Free subscription required)
44. National Institutes of Health (NIH). Coal Tar and Coal-Tar Pitch (2015)
45. City of Kingston. Residents: Coal Tar (2006)
46. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘coal tar’ and ‘coal-tar pitches’)
47. US Household Products Database (HPD). Household Products (Search term: ‘Coal tar’)

Other Resources

  1. Occupational Safety and Health Administration (OSHA). Safety and Health Topics: Asphalt Fumes
  2. International Agency for Research on Cancer (IARC). Monograph summary, Volume 35 (1985) (PDF)

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