CAREX Canada

Full Profile

CAS No. 71-43-2

Photo: Benzene^[1]

IARC Monograph Vol. 29, Suppl. 7, 1987 (Group 1)

IARC Monograph Vol. 100F, 2012 (Group 1)

General Information

Benzene, an aromatic hydrocarbon, is a clear, usually colourless liquid with a gasoline-like odour.^[2] Benzene occurs naturally as a constituent of crude oil and has been synthesized from coal since 1849 and from petroleum sources since 1941.^[2] Trace amounts of benzene are produced from the incomplete combustion of organic materials.^[3] Benzene may also be referred to as, benzol or coal naphtha.^[4] There are numerous other synonyms and product names; see HSDB for more information.^[4]

Benzene has been classified by IARC as Group 1, carcinogenic to humans.^[2,6] A recent 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 in acute lymphocytic leukaemia, chronic lymphocytic leukaemia, multiple myeloma and non-Hodgkin lymphoma.^[6] Benzene is considered a 'non-threshold toxicant,' where adverse effects may occur at any level of exposure.^[3]

Although the hematopoietic system is the main target for benzene toxicity, the immune, lymph and nervous systems are also adversely affected.^[7] Short-term exposure can cause drowsiness, headaches, and unconsciousness. The effects of long-term exposure include anaemia, neuropathies, and memory loss.^[7] Benzene is also a skin irritant.^[7]

Benzene has been ranked by CAREX Canada for both the occupational and environmental settings as Group A (immediate high priority). 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 (ppm)
Canada Labour Code	0.5 [sk] 2.5 [stel]
BC, AB, MB, NL, PE, NB, NS	0.5 [sk] 2.5 [stel]
ON	0.5 2.5 [stel]
QC	1 [em] 5 [stel]
YT	10 [c]
NT, NU	10 [sk] 25 [stel]
SK	ALARA (no limit listed)
Other Jurisdiction	OEL (ppm)
ACGIH 2011 TLV	0.5 [stel] 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

ALARA = as low as reasonably achievable

c = ceiling (not to be exceeded at any time)

Canadian Environmental Guidelines

Jurisdiction	Limit	Year
Canadian Drinking Water Guidelines	0.005 mg/L	2010^[8]
Cosmetic Hotlist	Not Permitted	2011^[9]

Benzene was not included in other Canadian government environmental guidelines reviewed.^[10,11]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL – low priority substance (already risk managed)	2006^[12]
CEPA	Schedule 1, paragraph 'c'	2011^[14]
CEPA	Benzene in Gasoline Regulations: 1.0% max. benzene (by volume) in supplied gasoline (Exceptions: aircraft use, vehicle competitions, scientific research)	2011^[15]

Benzene was not included in other Canadian government chemical listings reviewed.^[13]

Main Uses

Benzene is used primarily as a raw material in the production of chemicals including ethylbenzene, for styrene; cumene, for phenol and acetone; and cyclohexane, for nylon and synthetic fibres.^[2,7]

Benzene was formerly added to gasoline as an octane enhancer and anti-knock agent (along with toluene and xylene).^[3] Benzene is not generally not used as a gasoline additive any more in Canada, but it does occur naturally in crude oil and gasoline.^[16] Benzene has also been used in manufacturing of rubbers, lubricants, dyes, detergents, drugs and pesticides.^[7]

Canadian Production and Trade

In 2002 there were 7 facilities producing benzene – 4 in Ontario, 2 in Alberta and 1 in Quebec – with a production capacity of 1,142 kilotonnes.^[17]

Production and Trade

Activity	Quantity	Year
Canadian Production	976 kt	2005 (forecasted)^[17]
Domestic Consumption	776 kt	2005 (forecasted)^[17]
Export: Mainly to US	175,747 t of 'benzene'	2010^[19]
Import: Mainly from US	40,189 t of 'benzene'	2010^[19]

kt = kilotonne

t = tonne

Occupational Exposures

The major route of occupational exposure to benzene is inhalation, but dermal exposure can also occur.^[5,7]

Industries where exposure to benzene is likely to occur include benzene production in petrochemical plants, petroleum refining, and coke and coal chemical manufacturing; rubber tire manufacturing; and storage or transport of benzene and petroleum products containing benzene.^[20]

Occupations at risk of benzene exposure include steel workers, printers, rubber workers, shoe makers, laboratory technicians, firefighters, and gas station employees.^[20] Workers who spend significant time in motor vehicles in areas of congested traffic may also be exposed to benzene.^[5,7]

Environmental Exposures

The primary source of benzene exposure for the non-smoking population is from ambient air, due to both natural and anthropogenic sources.^[2] Anthropogenic releases, which make up the vast majority of exposure, are from combustion of gasoline and diesel fuels, natural gas dehydrators, residential wood combustion, steel production, petroleum distribution and refining, chemical manufacture, prescribed burning and cigarette smoke.^[3,18] Natural sources of benzene released into the environment include petroleum seeps, forest fires, volcanic eruptions, and emissions from vegetation.^[21]

Ambient air levels in Canada have been monitored since 1989 by the National Air Pollution Surveillance (NAPS) network. A 2003 update indicates that the concentration of benzene at eighteen urban sites (12 cities) has decreased 65% between 1990 and 2002.^[22] Annual mean levels have been below 2 µg/m³ since 1999.^[22] Rural concentrations changed very little over the measurement period, with annual means of approximately 0.5 µg/m³.^[22]

In the general population of smokers, as well as those exposed to Environmental Tobacco Smoke, cigarettes are the greatest source of direct exposure to benzene.^[7] Under certain conditions, there is potential for the formation of benzene in beverages and other foods containing benzoate salts and ascorbic acid (vitamin C).^[23]

Benzene contamination in soils and groundwater can arise from oil and gas spills, underground storage tanks, and seepage from waste disposal sites.^[4]

Searches of environmental and consumer product databases yielded the following results on current potential for exposure to benzene in Canada:

NPRI and US Household Products Database

NPRI 2009^[24]
Search term: 'benzene'
Category	Quantity	Industry
Released into Environment	645 t	Steelworks, petroleum refineries, mines, power plants (204 companies)
Disposed of	1,553 t
Sent to off-site recycling	1,862 t

US Household Products 2010^[25]
Search Term	# Products	Product Type
'benzene'	5	Interior paints (2), wood finish (1), adhesive remover (1), auto part cleaner/degreaser (1)