Carbon Tetrachloride Profile
INDUSTRIAL CHEMICALS – POSSIBLE CARCINOGEN (IARC 2B)
Contents
Carbon Tetrachloride Profile
General Information
Carbon tetrachloride (CCl4) is a volatile, colourless liquid with a mild, sweet odour.[1] It may also be referred to as tetrachloromethane or carbon tet.[2] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[2]
Carbon tetrachloride has been classified by the International Agency for Research on Cancer (IARC) as Group 2B, possibly carcinogenic to humans.[3] Workplace studies suggest an association between exposure to CCl4 and an increased incidence of non-Hodgkin lymphoma. The strength of the association, however, was statistically weak and inconclusive.[3] In animal studies, carbon tetrachloride caused liver, mammary gland, and adrenal gland cancers in rats and mice.[3]
Additionally, acute CCl4 exposure can cause gastrointestinal and neurological symptoms such as nausea, dizziness, dyspnea, vomiting, as well as liver damage and death in severe cases.[2]
Regulations and Guidelines
Occupational exposure limits (OEL) [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]
| Canadian Jurisdictions | OEL (ppm) |
|---|---|
| Canada Labour Code | 5 [sk] 10 [stel] |
| BC | 2 [sk] |
| AB, MB, NL, NB, NS, PE, QC | 5 [sk] 10 [stel] |
| SK, NT NU | ALARA |
| ON | 2 [sk] 3 [stel] |
| YT | 10 [sk] 20 [stel] |
| Other Jurisdictions | OEL (ppm) |
| ACGIH 2020 TLV | 5 [sk] 10 [stel] |
ppm = parts per million
sk = easily absorbed through the skin
stel = short term exposure limit (15 min. maximum)
ALARA = as low as reasonably achievable
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value (8 hour maximum)
Canadian environmental guidelines and standards*
| Jurisdiction | Limit | Year |
|---|---|---|
| Canadian Drinking Water Guidelines | MAC: 0.002 mg/L | 2017[19] |
| Ontario Drinking Water Standards | MAC: 0.002 mg/L | 2016[20] |
| Quebec and Saskatchewan Drinking Water Standards | MAC: 0.005 mg/L | 2014[21] 2020[22] |
| Ontario Ambient Air Quality Criteria | 24 hour: 2.4 µg/m3 | 2016[23] |
| Ontario’s Air Pollution – Local Air Quality Regulation | 24 hour standard: 2.4 µg/m3; Prohibited discharge into the air if the concentration of carbon tetrachloride exceeds the standard | 2020[24] |
| Health Canada Cosmetics Hotlist | Not Permitted | 2010[25] |
| BC’s Contaminated Sites Regulation, BC Reg 375/96 |
Sets 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: 5,000 μg/g
Drinking water: 2 μg/L Sets vapour standards for the protection of human health: |
2017[26] |
*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 acceptable concentration
mg/L = milligrams per litre
µg/m3 = micrograms per cubic metre
Canadian agencies/organizations
| Agency | Designation/Position | Year |
|---|---|---|
| Health Canada | DSL – low priority substance; already risk managed | 2006[27] |
| CEPA | Schedule 1 | 2010[28] |
| Environment Canada’s National Pollutant Release Inventory | Reportable to NPRI if manufactured, processed, or otherwise used at quantities greater than 10 tonnes | 2016[29] |
| National Classification System for Contaminated Sites | Rank: “High hazard”, potential human carcinogen | 2008[30] |
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act
Carbon tetrachloride was not included in other Canadian government guidelines, standards, or chemical listings reviewed.
Main Uses
Before chlorofluorocarbons (CFCs) were phased out due to their ozone depleting properties, the major use of carbon tetrachloride was to produce them, including trichlorofluoromethane (Freon 11) and dichlorodifluoromethane (Freon 12).[3,31] CFCs were widely used as refrigerants, aerosol propellants, and solvents.[3]
Carbon tetrachloride was formerly used as a fumigant pesticide for grains.[3] This use ceased in Canada in 1984.[32] It was also used as a solvent, in fire extinguishers, as a dry cleaning agent, and as a degreaser in both industrial and household settings.[31]
In Canada, carbon tetrachloride is no longer produced or used to make any substance that causes ozone depletion. However, use is still permitted for manufacturing other substances.[33]
Canadian Production and Trade
Canada ceased the production of carbon tetrachloride in 1995 Following the Montreal Protocol agreement, which was put in place to decrease the production and consumption of ozone depleting substances.[34,35]
Zero tonnes were exported in 2021, but 3 tonnes and 4 tonnes were exported in 2018 and 2019, respectively.[36]
Production and trade
| Activity | Quantity | Year |
|---|---|---|
| Export | 0 t (of ‘carbon tetrachloride’) | 2021[36] |
| Import | 90 t (of ‘carbon tetrachloride’) | 2021[36] |
t = tonne
Environmental Exposures Overview
Carbon tetrachloride does not occur naturally in the environment; therefore, CCl4 present in the environment originates from anthropogenic releases.[2,31] Releases mostly occur directly into the atmosphere (73%).[31] Due to its high volatility, nearly all environmental releases into other media, such as soil and water, end up in the air.[31,37]
Carbon tetrachloride is a persistent chemical in air, with an average half-life of 30 to 100 years.[36] Therefore, it has gradually accumulated in the environment over time[38] and is now ubiquitous in outdoor and indoor air.[37] A Canada-wide survey reported concentrations of CCl4 ranging from 0.34-1.02 µg/m3 (0.60 µg/m3 average) in nearly 7,000 ambient air samples collected across 17 rural and 40 urban sites.[37] Reported indoor air concentrations were similar.
Public exposures are most likely to occur by inhaling contaminated air and consuming contaminated water.[38,37] One survey of 48 homes in Windsor, Ontario found that the levels of CCl4 in indoor air were higher in the summer (mean 0.72 µg/m3) compared to the winter (mean 0.60 µg/m3).[37]
Carbon tetrachloride is also commonly detected in surface water, groundwater and drinking-water.[3,31,37] Concentrations of CCl4 in surface water in Canada are typically below 1 µg/L.[37] Concentrations may be higher in groundwater systems where volatilization and degradation are limited, or if there are effluents from nearby waste or industrial sites.[3,31,37]
Carbon tetrachloride has been found in effluents from a variety of industries, including metal manufacturing and finishing, foundries, paint and ink manufacturing, and petroleum refining.[3] In addition to ingestion, inhalation and dermal exposures are also possible when using contaminated water for bathing and other purposes.[31] Exposure may have occurred in the past through using CCl4-containing consumer products and consuming food fumigated with CCl4.[1] Because CCl4 is no longer used in these applications in Canada, exposures via food and consumer products are considered unlikely.[1,37]
There were no reportable releases of carbon tetrachloride to the National Pollutant Release Inventory (NPRI) in Canada in 2014.[39]
Occupational Exposures Overview
Inhalation is the most important route of exposure to carbon tetrachloride in occupational settings.[31]
In the past, high levels of occupational exposure occurred while using CCl4 as a dry-cleaning agent and grain fumigant.[31,38] Average and peak exposures during dry cleaning operations were measured as high as 338 ppm and 7,100 ppm, respectively.[38] Average CCl4concentrations reported in storage spaces with fumigated grain were mostly well below 5 ppm, but could reach as high as 60 ppm.[31]
Current occupational exposures may occur while using CCl4 in chemical manufacturing processes and in research laboratories.[3]
CAREX Canada has not prioritized carbon tetrachloride for exposure estimate development. This is because the likelihood of exposure in Canadian workers is very low.
Sources
Photo: Wikimedia Commons, Achim Hering
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