Carbon tetrachloride (CCl4) is a volatile, colourless liquid with a mild, sweet odour. It may also be referred to as tetrachloromethane or carbon tet. There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.
Carbon tetrachloride has been classified by the International Agency for Research on Cancer (IARC) as Group 2B, possibly carcinogenic to humans. 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. In animal studies, carbon tetrachloride caused liver, mammary gland, and adrenal gland cancers in rats and mice.
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.
National Classification System for Contaminated Sites
Rank: "High hazard", potential human carcinogen
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act
Carbon tetrachloride was not included in other Canadian government listings reviewed.[16,17]
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).[4,18] CFCs were widely used as refrigerants, aerosol propellants, and solvents.
Carbon tetrachloride was formerly used as a fumigant pesticide for grains. This use ceased in Canada in 1984. 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.
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.
Canadian Production and Trade
Production and Trade
57 t of 'carbon tetrachloride'
t = tonne
Inhalation is the most important route of exposure to carbon tetrachloride in occupational settings.
In the past, high levels of occupational exposure occurred while using CCl4 as a dry-cleaning agent and grain fumigant.[18,22] Average and peak exposures during dry cleaning operations were measured as high as 338 ppm and 7,100 ppm, respectively. Average CCl4 concentrations reported in storage spaces with fumigated grain were mostly well below 5 ppm, but could reach as high as 60 ppm.
Current occupational exposures may occur while using CCl4 in chemical manufacturing processes and in research laboratories.
CAREX Canada has not prioritized carbon tetrachloride for exposure estimate development. This is because the likelihood of exposure in Canadian workers is very low.
Carbon tetrachloride does not occur naturally in the environment; therefore, CCl4 present in the environment originates from anthropogenic releases.[3,18] Releases mostly occur directly into the atmosphere (73%). Due to its high volatility, nearly all environmental releases into other media, such as soil and water, end up in the air.[18,23]
Carbon tetrachloride is a persistent chemical in air, with an average half-life of 30 to 100 years. Therefore, it has gradually accumulated in the environment over time and is now ubiquitous in outdoor and indoor air. 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. Reported indoor air concentrations were similar.
Public exposures are most likely to occur by inhaling contaminated air and consuming contaminated water.[22,23] 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).
Carbon tetrachloride is also commonly detected in surface water, groundwater and drinking-water.[4,18,23] Concentrations of CCl4 in surface water in Canada are typically below 1 µg/L. Concentrations may be higher in groundwater systems where volatilization and degradation are limited, or if there are effluents from nearby waste or industrial sites.[4,18,23]
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. In addition to ingestion, inhalation and dermal exposures are also possible when using contaminated water for bathing and other purposes. Exposure may have occurred in the past through using CCl4-containing consumer products and consuming food fumigated with CCl4. Because CCl4 is no longer used in these applications in Canada, exposures via food and consumer products are considered unlikely.[2,23]
There were no reportable releases of carbon tetrachloride to the National Pollutant Release Inventory (NPRI) in Canada in 2014.
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 carbon tetrachloride on the 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.