Benzene, an aromatic hydrocarbon, is a clear, usually colourless liquid with a gasoline-like odour. Benzene occurs naturally as a constituent of crude oil. It has been synthesized from coal since 1849 and from petroleum sources since 1941. Trace amounts of benzene are produced from the incomplete combustion of organic materials. Benzene may also be referred to as benzol or coal naphtha. There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.
Benzene has been classified by the International Agency for Research on Cancer (IARC) as Group 1, carcinogenic to humans.[2,5] The 2012 review of Group 1 agents by IARC reaffirmed this classification, citing sufficient evidence for human carcinogenicity for acute non-lymphocytic leukaemia, and limited evidence of carcinogenicity for acute lymphocytic leukaemia, chronic lymphocytic leukaemia, multiple myeloma, and non-Hodgkin lymphoma.
Although the hematopoietic system is the main target for benzene toxicity, the immune, lymph and nervous systems are also adversely affected by exposure. Short-term exposure can cause drowsiness, headaches, and unconsciousness. The effects of long-term exposure include anaemia, neuropathies, and memory loss. Benzene is also a skin irritant.
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
Canadian Drinking Water Guidelines
Quebec’s Drinking Water Standards
MAC: 0.5 µg/L
Alberta Ambient Air Quality Objectives
1 hour: 30 µ/m3
Annual: 3 µ/m3
Ontario Ambient Air Quality Criteria
24 hour: 2.3 µ/m3
BC’s Contaminated Sites Regulation, BC Reg 375/96
For the protection of human health, sets soil standards for:
Intake of contaminated soil: Agricultural, urban park, and residential soil: 1,000 µg/g Commercial soil: 4,000 µg/g Industrial soil: 6,500 µg/g
Groundwater used for drinking water: 0.04 µg/g
MAC = maximum allowable concentration
Benzene was not included in other Canadian government environmental guidelines reviewed.[13,14]
National Classification System for Contaminated Sites
Rank = “High hazard”, potential human carcinogen
Agreement Respecting the Great Lakes Basin Ecosystem
Listed as a “Hazardous Polluting Substance
Benzene in Gasoline Regulations: 1.0% max. benzene (by volume) in supplied gasoline (Exceptions: aircraft use, vehicle competitions, scientific research)
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act
Benzene was not included in other Canadian government chemical listings reviewed.
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.[2,6]
Benzene was formerly added to gasoline as an octane enhancer and anti-knock agent (along with toluene and xylene). Benzene is generally no longer used as a gasoline additive in Canada, but it does occur naturally in crude oil and gasoline. Benzene has also been used to manufacture rubbers, lubricants, dyes, detergents, drugs, and pesticides.
Canadian Production and Trade
Production and Trade
106,445 t of 'benzene'
80,883 t of 'benzene'
t = tonne
The most important route of occupational exposure to benzene is inhalation, but dermal exposure can also occur.[2,6]
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.
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.
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. Combustion sources such as fireplaces, gas furnaces, cigarette smoke, and vehicles in attached garages may also contribute to indoor concentrations of benzene. Having an attached garage can lead to increased exposure since benzene can more readily enter the house. 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. 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. 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. 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.[3,24] Natural sources of benzene in the environment include forest fires, volcanos, petroleum seepage, and emissions from vegetation.
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.
Low levels of benzene are found in some soft drinks and a number of other foods and beverages.[30,31] Benzene contamination in soils and groundwater may also arise from oil and gas spills, underground storage tank leaks, and seepage from waste disposal sites. 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
Substance name: 'Benzene'
Released into Environment
Oil and gas extraction, basic chemical manufacturing, iron and steel mills and ferro-alloy manufacturing, petroleum and coal product manufacturing (234 facilities)
Sent to off-site recycling
US Household Products 2010
adhesives (4), interior paints (2), wood finish (1), adhesive remover (1), pet care lotion (1), auto part cleaner/degreaser (5), motor oil (3),
t = tonne
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 here to learn more about policies specific to benzene inthe 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.