Benzene Profile


CAS No. 71-43-2
IARC Monograph Vol. 29, Suppl. 7, 1987 (Group 1)
IARC Monograph Vol. 100F, 2012 (Group 1)
IARC Monograph Vol. 120, 2018 (Group 1)

Benzene Profile


  • A naturally occurring substance in crude oil; also produced from the incomplete combustion of organic materials
  • Associated cancer: Acute non-lymphocytic leukemia
  • Most important route of exposure: Inhalation; skin contact
  • Uses: As a raw material to produce other chemicals such as styrene and acetone, as well as synthetic fibres
  • Occupational exposures: Approx. 375,000 Canadians are exposed at work, often via motor vehicle exhaust
  • Environmental exposures: Primarily in indoor air via a number of sources including glues, paints, and combustion sources (ex. fireplaces)
  • Fast fact: Benzene is considered a ‘non-threshold toxicant’, where adverse health effects may occur at any exposure level.

General Information

Benzene, an aromatic hydrocarbon, is a clear, usually colourless liquid with a gasoline-like odour.[1] Benzene occurs naturally as a constituent of crude oil. It has been synthesized from coal since 1849 and from petroleum sources since 1941.[1] Trace amounts of benzene are produced from the incomplete combustion of organic materials.[2] Benzene may also be referred to as benzol or coal naphtha.[3] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[3]

Benzene has been classified by the International Agency for Research on Cancer (IARC) as Group 1, carcinogenic to humans.[1,4] The 2017 review by IARC reaffirmed this classification, citing sufficient evidence of human carcinogenicity for acute non-lymphocytic leukemia/acute myeloid leukemia and limited evidence of carcinogenicity for chronic lymphocytic leukemiamultiple myeloma, and non-Hodgkin lymphoma. Positive associations were also observed for chronic myeloid leukemia and lung cancer.[4]

Although the hematopoietic system is the main target for benzene toxicity, the immune, lymph and nervous systems are also adversely affected by exposure.[5] Short-term exposure can cause drowsiness, headaches, and unconsciousness. The effects of long-term exposure include anaemia, neuropathies, and memory loss.[5] Benzene is also a skin irritant.[5]

Regulations and Guidelines

Occupational exposure limits (OEL) [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

Canadian JurisdictionsOEL (ppm)
Canada Labour Code0.5 [sk]
2.5 [stel]
AB, BC, MB, NB, NS, NL, ON, PE0.5 [sk]
2.5 [stel]
QC1 [em]
5 [stel]
YT10 [c]
SK, NU, NTALARA (no limit listed)
Other JurisdictionOEL (ppm)
ACGIH 2020 TLV0.5 [sk]
2.5 [stel]
ppm = parts per million
sk = easily absorbed through the skin
stel = short term exposure limit (15 min. maximum)
em = exposure must be reduced to the minimum
c = ceiling (not to be exceeded at any time)
ALARA = as low as reasonably achievable
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

Canadian environmental guidelines and standards*

Drinking Water Guidelines (Canada, BC, MB) and Standards (SK)0.005 mg/L2009-2020
Ontario Drinking Water Quality Standards0.001 mg/L2016[25]
Quebec’s Drinking Water StandardsMAC: 0.5 µg/L2014[26]
Government of Canada’s residential indoor air quality guidelinesALARA2013[27]
Alberta Ambient Air Quality Objectives

1 hour: 30 µg/m3
Annual: 3 µg/m3

Ontario Ambient Air Quality Criteria24 hour: 2.3 µg/m3
Annual: 0.45 µg/m3
Ontario’s Air Pollution – Local Air Quality regulation standardsAnnual: 45 µg/m3; Prohibited discharge into the air if the concentration of benzene exceeds the standard2020[30]
Quebec’s Clean Air Regulation24 hour limit: 10 µg/m3; Prohibited discharge into the air if the concentration of benzene exceeds the standard2011[31]
BC’s Contaminated Sites Regulation, BC Reg 375/96Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 150 μg/g
Urban park and high density residential sites: 350 μg/g
Commercial sites: 1,000 μg/g
Industrial sites: 6,500 μg/g


Drinking water: 5 μg/L

Sets vapour standards (for vapours derived from soil, sediment, or water) for the protection of human health:
Agricultural, urban park, residential use standard: 1.5 μg/m3
Commercial use standard: 4 μg/m3
Industrial use standard: 10 μg/m3
Parkade use standard: 10 μg/m3

Cosmetic HotlistNot Permitted2011[33]
*Standards are legislated and legally enforceable, while guidelines (including Ontario ambient air quality criteria) describe concentrations of contaminants in the environment (e.g. air, water) that are protective against adverse health, environmental, or aesthetic (e.g. odour) effects
MAC = maximum allowable concentration
ALARA = as low as reasonable achievable

Canadian agencies/organizations

Health CanadaDSL – low priority substance (already risk managed)2006[34]
CEPASchedule 1, paragraph ‘c’2011[35]
National Classification System for Contaminated SitesRank = “High hazard”, potential human carcinogen2008[36]
Benzene in Gasoline Regulations1.0% max. benzene (by volume) in supplied gasoline
(Exceptions: aircraft use, vehicle competitions, scientific research)
Environment Canada’s National Pollutant Release InventoryReportable to NPRI if released at quantities greater than 1 tonne of 10-tonne total VOC air release or if manufactured, processed, or otherwise used at quantities greater than 10 tonnes2016[38]
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act

Benzene was not included in other Canadian government guidelines, standards, or chemical listings reviewed.

Main Uses

Benzene is used primarily as a raw material to produce chemicals including: ethylbenzene, for styrene; cumene, for phenol and acetone; and cyclohexane, for nylon and synthetic fibres.[1,5]

Benzene was formerly added to gasoline as an octane enhancer and anti-knock agent (along with toluene and xylene).[2] Benzene is generally no longer used as a gasoline additive in Canada, but it does occur naturally in crude oil and gasoline.[39] Benzene has also been used to manufacture rubbers, lubricants, dyes, detergents, drugs, and pesticides.[5]

Canadian Production and Trade

Production and trade

Export106,445 t of ‘benzene’2015[40]
Import80,883 t of ‘benzene’2015[40]
t = tonne

Environmental Exposures Overview

CAREX Canada estimates that the primary source of environmental exposure to benzene is indoor air. Benzene is emitted by a number of indoor sources, including glues, paints, furniture wax, and some detergents.[41] Combustion sources such as fireplaces, gas furnaces, cigarette smoke, and vehicles in attached garages may also contribute to indoor concentrations of benzene.[42] Having an attached garage can lead to increased exposure since benzene can more readily enter the house.[43] For example, in Canada, benzene levels are three times higher in homes with attached garages compared to those with detached or no garages. The presence of benzene is attributable to engine exhaust, as well as to the evaporation of benzene from gasoline.[43] A recent survey of homes across Canada found indoor concentrations of benzene ranging from 0.10 to 15.19 µg/m3, with average concentrations of 1.93 µg/m3.[44] CAREX Canada’s environmental estimates indicate that benzene levels in indoor and outdoor air may be sources of elevated cancer risk (high data quality).

Outdoor concentrations of benzene are generally lower than indoor concentrations.[45] Major sources of benzene in outdoor air include vehicle combustion of gasoline and diesel fuels, residential fuel combustion, iron and steel production, chemical manufacturing, as well as petroleum and coal products manufacturing.[2,41] Natural sources of benzene in the environment include forest fires, volcanos, petroleum seepage, and emissions from vegetation.[41]

Ambient air benzene levels in different locations in Canada have been monitored since 1989 by the National Air Pollution Surveillance (NAPS) network. A 2012 NAPS update indicated that the concentrations of benzene at 18 urban sites decreased by 74% between 1994 and 2009.[46]

Low levels of benzene are found in some soft drinks and a number of other foods and beverages.[47,48] Benzene contamination in soils and groundwater may also arise from oil and gas spills, underground storage tank leaks, and seepage from waste disposal sites.[3] CAREX Canada’s environmental estimates indicate that benzene levels in food and beverages may be sources of elevated cancer risk (very low data quality), although not in drinking water (moderate data quality).

Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Household Products Database yielded the following results on current potential for exposure to benzene in Canada:

NPRI and US Household Products Database

NPRI 2015[49]
Substance name: ‘Benzene’
Released into Environment736 tOil and gas extraction,
basic chemical manufacturing,
iron and steel mills and ferro-alloy manufacturing,
petroleum and coal product manufacturing
(234 facilities)
Disposed of1,065 t
Sent to off-site recycling1,055 t
US Household Products 2016[50]
Search Term# ProductsProduct Type
‘Benzene’17adhesives (3), interior paints (2), wood finish (1),
adhesive remover (1), pet care lotion (1), sealant (1),
auto part cleaner/degreaser (5), motor oil (3)
t = tonne

For more information, see the environmental exposure estimate for benzene.

Occupational Exposures Overview

The most important route of occupational exposure to benzene is inhalation, but dermal exposure can also occur.[1,5]

CAREX Canada estimates that approximately 375,000 Canadian workers are exposed to benzene; most exposures occur in the low exposure category. Many workers are exposed to benzene via inhalation of motor vehicle exhaust.

Industries where the largest numbers of workers are exposed include automotive repair and maintenance, taxi and limo service, printing and related support services, public administration (where firefighters are included), and automobile dealers. According to the US Department of Labour, benzene exposure is also likely during petrochemical production, petroleum refining, coke and coal chemical manufacturing, tire manufacturing, and storage or transport of benzene and petroleum products containing benzene.[51]

Occupations at risk of benzene exposure include automotive service technicians and mechanics, delivery and courier drivers, taxi and limousine drivers, and firefighters. Other occupations such as steel workers, printers, rubber workers, shoemakers, laboratory technicians, and gas station employees were also identified as exposed.[51]

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


Photo: Wikimedia Commons, Ilya Plekhanov

1. National Toxicology Program (NTP). 14th report on carcinogens for Benzene (2016) (PDF)
3. US National Library of Medicine. Hazardous Substances Data Bank (Search term: ‘Benzene’)
4. International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of benzene (2018)
5. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Benzene (2007) (PDF)
11. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2018)
12. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2020) (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 (2020) (PDF)
20. Occupational Safety and Health Administration (OSHA). Annotated PELs (2020)
22. Government of British Columbia. Source Drinking Water Quality Guidelines (2020) (PDF)
24. Government of Manitoba, Manitoba Water Stewardship. Manitoba Water Quality Standards, Objectives, and Guidelines (2011) (PDF)
25. The Canadian Legal Information Institute (CanLII). Ontario Drinking Water Quality Standards, O Reg 169/03 (2020)
26. The Canadian Legal Information Institute (CanLII). Regulation respecting the quality of drinking water, CQLR c Q-2, r 40 (2020)
27. Government of Canada. Residential indoor air quality guidelines (2020)
28. Alberta Environment and Parks. Ambient Air Quality Objectives (2019)
29. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2019)
31. Government of Quebec. Clean Air Regulation, Q-2, r. 4.1 (2020)
32. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2019)
33. Health Canada. Cosmetic Ingredient Hotlist (2019)
34. Health Canada. Prioritization of the DSL (2006)
35. Environment and Climate Change Canada. CEPA List of Toxic Substances (2020)
36. Canadian Council of Ministers of the Environment. National Classification System for Contaminated Sites (PDF) (2008)
37. Environment Canada. Benzene in Gasoline Regulations (1997) (PDF)
40. International Trade Centre. TradeMap (Free subscription required)
42. Héroux ME, Clark N, Van Ryswyk K, Mallick R, Gilbert NL, Harrison I, Rispler K, Wang D, Anastassopoulos A, Guay M, MacNeill M, Wheeler AJ. “Predictors of Indoor Air Concentrations in Smoking and Non-Smoking Residences.” Intern Journ of Environ Res and Public Health 2010;7:3080-3099. (PDF)
45. Health Canada. Benzene in Indoor Air (2013) (PDF)
46. Canadian Council of Ministers of the Environment (CCME). Canada-wide standard for benzene: 2010 final report (2012) (PDF)
47. Nyman PJ, Diachenko GW, Perfetti GA, McNeal TP, Hiatt MH, Morehous KM. “Survey Results of Benzene in Soft Drinks and Other Beverages by Headspace Gas Chromatography/Mass Spectrometry.” J Agric Food Chem 2008;56(2):571-576.
48. Cao X-L, Sparling M, Dabeka R. “Occurrence of 13 volatile organic compounds in foods from the Canadian total diet study.”Food Addit Contam Part A 2016;33(2):373-382
49. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI) Facility Search (Substance name: ‘Benzene’)
50. US Household Products Database. Household Products (Search term: ‘Benzene’)
51. Occupational Safety and Health Administration (OSHA). Benzene: Exposure Evaluation


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