Bitumens

Full Profile

General Information

Bitumen refers to the tar-like petroleum deposits found in oil sands. Generally, this thick, black, viscous crude oil must be heated or diluted with hydrocarbons before it will flow.^[10]

The terms bitumen and bitumens, oxidized may be used interchangeably with asphalt and asphalt, oxidized, respectively.^[2] Other synonyms for bitumen are "asphaltic bitumen," "asphaltum," and "petroleum asphalt".^[2] When sold in its natural state, bitumen is used only for road paving;^[18] it must be processed rigorously for use in gasoline and diesel fuel production.^[10]

Bitumens are classified as follows^[4]:

1. Bitumen (CAS # 8052-42-4) has undergone a non-destructive distillation process during petroleum refining.
2. Extracts of steam-refined and air-refined bitumens (CAS # 64742-93-4) have been oxidized by blowing air through at elevated temperatures, to produce desirable properties for industrial use in paving and roofing.

Bitumen is generally composed of aliphatic compounds, cyclic alkanes, aromatic hydrocarbons, and heterocyclic compounds.^[16] It is thought that fumes produced by heating asphalt at high temperatures are more likely to generate carcinogenic polycyclic aromatic compounds, such as benzo(a)pyrene, than fumes produced at lower temperatures.^[16] The chemical composition of asphalt depends on both the petroleum source and the manufacturing process,^[4] making it difficult to identify the specific component(s) responsible for adverse health effects in exposed workers.^[16]

Extracts of steam-refined and air-refined bitumens (Bitumens, oxidized) have been classified by IARC as Group 2B, possibly carcinogenic to humans, with evidence from animal studies showing an increase in tumours at the site of injection in rats and mice, and tumours following skin application in mice.^[2] IARC has classified Bitumens as Group 3, not classifiable as to their carcinogenicity to humans. Although there is some indication of increased cancer rates in humans, including lung, oral & skin, epidemiological studies have been inconclusive due to concomitant exposure to coal tar pitches and other materials in roofing and paving asphalts.^[2,4]

Other adverse health effects following exposure to asphalt may include eye, respiratory system and skin irritation.^[4,16] Dermal burns can occur when handling hot asphalt.^[4]

Bitumens and extracts of steam-refined and air-refined bitumens have been ranked by CAREX Canada as Group A (immediate high priority) for occupational settings and as Group B (possible high priority) for environmental settings. 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 [i]
Canada Labour Code	0.5 [i]
BC, AB, QC	5 [asphalt fume]
SK	0.5 [i] 1.5 [stel]
MB, NL, NB, NS, PE, ON	0.5 [i]
YT, NT, NU	5 [asphalt fume] 10 [stel]
Other Jurisdiction	OEL (mg/m3)
ACGIH 2011 TLV	0.5 [i]

Canadian Environmental Guidelines

Bitumen was not included in the Canadian government environmental guidelines reviewed.^[11-14]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL – high priority substance with the greatest potential for exposure	2006[7]

Bitumen was not included in other Canadian government chemical listings reviewed.^[8-9]

Main Uses

The majority of asphalt produced in the US is used in paving and roofing operations; only about 1% is used for waterproofing, damp-proofing, insulation, and paints.^[16]

Other uses for bitumen are in hydraulics, to protect metals against corrosion,^[1] and in electrical laminate adhesives, synthetic turf bases and sound insulation materials.^[1,4]

More than 80% of bitumen is used in various forms of road construction and maintenance.^[1]

Canadian Production and Trade

Alberta's oil sands are one of the world's two largest sources of bitumen,^[10] amounting to an estimated 269 billion cubic metres.^[18] The oil sands underlie 140,000 square kilometres^[18] and occur mainly in three regions: Athabasca (Fort McMurray), Peace River, and Cold Lake (North of Lloydminster).^[18]

Bitumen is produced through open-pit mining and in-situ (welling) methods.^[18] Commercially mined oil sands consist of approximately 10-12% bitumen, 83-85% mineral matter and 4-6% water.^[18]

Production and Trade

Activity	Quantity	Year
Alberta Production*	94,000,000 t of "crude bitumen"	2010[20]
	206,000,000 t of "crude bitumen"	2020 (forecasted)[20]
Export: Mainly to US	1,500,000 t of 'petroleum bitumen'	2010[3]
Export: Mainly to US, UK	174,000 t of 'bitumen & asphalt, natural; shale & tar sands; asphaltites & asphaltic rocks'
Import: Mainly from US	536,000 t of 'petroleum bitumen'
Import: Mainly from US	196,000 t of 'bitumen & asphalt, natural; shale & tar sands; asphaltites & asphaltic rocks'

Occupational Exposures

Occupational exposure is most significant through the inhalation of bitumen fumes or dusts; skin exposure may also occur.^[1]

Occupations primarily exposed to bitumen include those in hot-mix plants, roofing applications, paving, and roofing manufacturing.^[4] Workers involved in transport, storage, production, handling, or other use of bitumen may also be exposed.^[1]

Adding small amounts of polymer to asphalt has been found in initial field studies to dramatically reduce fume emissions from heated asphalt.^[13]

Environmental Exposures

There is limited data available on environmental asphalt concentrations in drinking water, foodstuffs and soil.^[4] Sources of environmental exposure include inhalation of roofing and paving fumes and runoff from paved roads.^[4]

Bitumen is not reportable to the National Pollutant Release Inventory (NPRI) in Canada.^[5]

A search of the US Household Products Database (search term 'bitumen') yielded over 60 products containing bitumens as an ingredient – all were asphalt products.^[6]

Sources

1. Hazardous Substances Database entry for Bitumens (Search term: 'asphalt')
2. IARC monograph summary, Volume 35, Suppl. 7, 1987 (PDF)
3. TradeMap (Free subscription required)
4. International Program on Chemical Safety (IPCS) Concise International Chemical Assessment Document: Asphalt (Bitumen)
5. The National Pollutant Release Inventory
6. Household Products Database (US)
7. Health Canada's Prioritization of the DSL (2006)
8. CEPA List of Toxic Substances (1999)
9. List of All Challenge Substances, Government of Canada Chemicals Management Plan (2009)
10. Government of Alberta: What is Oil Sands (2008)
11. Guidelines for Canadian Drinking Water (2010)
12. Health Canada Exposure Guidelines for Residential Indoor Air Quality (1987) (PDF)
13. Health Canada (2010) Cosmetic Ingredient Hotlist
14. Health Canada (2006) Food Additives Permitted for Use in Canada
15. CDC: Asphalt Fume Exposures During the Application of Hot Asphalt to Roofs, Current Practices for Reducing Exposures (2003) (PDF)
16. CDC: Health Effects of Occupational Exposure to Asphalt (2000) (PDF)
17. IARC: Complete List of Agents evaluated and their classification (2011) (PDF)
18. Marsh JH (Ed). Canadian Encyclopedia: Bitumen
19. Wikimedia Commons photo: Refined Bitumen
20. Government of Alberta News Release: June 6, 2011

Other Resources

1. Health Canada, Canadian Handbook on Health Impact Assessment, Volume 4: By Industry Sector (2004)
2. The Shell Bitumen Handbook