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Canada - Final Regulatory Action
1,2,3,5-Tetrachlorobenzene CAS number:
Date circular:

Chemical name: Benzene, 1,2,3,5-tetrachloro-

Final regulatory action has been taken for the category: Industrial

Final regulatory action: The chemical is Severely Restricted

Use or uses prohibited by the final regulatory action:

The Regulations prohibit the manufacture, use, sale, offer for sale or import of TeCBs, with the exception listed below.

Use or uses that remain allowed:

The Regulations do not apply to any use of TeCBs with any chlorobiphenyls that have the molecular formula C12H(10-n)Cln in which "n" is greater than 2.

The final regulatory action was based on a risk or hazard evaluation: Yes

Summary of the final regulatory action:

The Prohibition of Certain Toxic Substances Regulations, 2005 prohibit the manufacture, use, sale, offer for sale and import of toxic substances listed in Schedules 1 and 2 to the Regulations. TeCBs are found in Schedule 2, which lists substances that are subject to prohibitions related to concentration or use.

The reasons for the final regulatory action were relevant to: Environment

Summary of known hazards and risks to the environment:

TeCBs appeared on the first Priority Substances List (PSL1) of the original Canadian Environmental Protection Act (CEPA). PSL1 was published in the Canada Gazette, Part I, on February 11, 1989. Assessments were performed to determine whether these chlorobenzenes (CBzs) should be considered toxic as defined under CEPA and were completed in 1993. Section 11 of CEPA defined toxic as follows: For the purposes of this Part, a substance is toxic if it is entering or may enter the environment in a quantity, concentration or under conditions
a)having or that may have an immediate or long-term effect on the environment;
b)constituting or that may constitute a danger to the environment on which human life depends; or
c)constituting or that may constitute a danger in Canada to human life or health.
It was concluded at that time that these substances do not constitute a danger either to the environment on which human life depends or to human life or health, and, therefore, they were not found to be toxic under Paragraph 11(b) or 11(c) of CEPA.
Additionally, during the period over which the original assessments were conducted, it was determined that concentrations of TeCBs present in Canadian air and surface waters were not likely to cause adverse effects on aquatic biota or wildlife. There was, however, a lack of acceptable data on the effects of these CBzs on benthic and soil-dwelling organisms and on concentrations of CBzs in Canadian soils. Therefore, it was not possible to determine whether environmental harm was occurring due to accumulations of these substances in sediment and soil.
The lack of data led to the conclusion that there was insufficient information available on sediments and soils to determine whether these substances should be considered toxic under Paragraph 11(a) of CEPA. CEPA was subsequently revised in 1999. Paragraph 64(a) of CEPA 1999 expands the definition of toxic from the original Paragraph 11(a) to include effects on biodiversity. CEPA 1999 places more emphasis on pollution prevention, gives consideration to the precautionary principle and requires special treatment of persistent and bioaccumulative substances. Substances that are shown to be both persistent and bioaccumulative, therefore, will be assessed using a more conservative approach than is used for other substances.
As a result of the publication of the PSL Assessment Reports for the CBzs, additional studies were designed and funded. Data on the toxicity of TeCBs to freshwater and marine benthic organisms was reported. Additionally, concentrations of TeCBs were determined in sediments near point sources (i.e., outfalls from sewage treatment plants and textile manufacturing plants) in Atlantic Canada. Laboratory studies included toxicity testing to determine effects of exposure to sediments from point source locations.
A literature search for new data on the CBz substances of interest was performed in 1995 and repeated in 1999. The National Pollutant Release Inventory (NPRI) and Accelerated Reduction/Elimination of Toxics databases supported by Environment Canada were also reviewed for CBz data.
The focus of the follow up report was the determination of whether accumulations of specific CBzs in aquatic sediments or soils would harm exposed benthic or soil-dwelling organisms.
Estimated average half-life in surface sediment is approximately 2 years for TeCBs. Additionally, the tetrachlorinated congeners have been identified in sediments from lakes in both temperate regions and northern Canadian environments.
TeCBs have been reported in sediments dated to the early 1900s, although maximum concentrations were reported to occur between the 1970s and 1980s. These data are consistent with half-life estimates exceeding 1 year in a variety of sediments. Mean half-lives in soil have been estimated to be approximately 8 months for TeCBs, therefore, likely to persist in soils under aerobic conditions.
TeCBs have been identified in sediments from lakes in both temperate regions and northern Canadian environments. The detection of the TeCBs in northern lake sediments in the absence of nearby sources indicates that these residues are a result of long-range atmospheric transport, and these CBzs, therefore, meet the criteria for persistence in air.
On the basis of the available information, it was concluded that TeCBs are persistent in soil, sediment and in air, according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999.
Reported bioaccumulation factors (BAFs) for TeCBs ranged between 1180 and 135 000. The log Kow estimate for TeCBs was 4.5.
TeCBs are also bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999.
It was concluded that concentrations of TeCBs in Canadian soil are unlikely to be causing harm to populations of soil-dwelling organisms. However, it was possible that concentrations of TeCBs in sediment from the St. Clair River near Sarnia may have been harming benthic organisms.
Based on available data, TeCBs were entering the environment in a quantity or concentration or under conditions that had or may have had an immediate or long-term harmful effect on the environment or its biological diversity and that TeCBs are considered toxic, as defined under Paragraph 64(a) of CEPA 1999.

Expected effect of the final regulatory action in relation to the environment:

TeCBs are persistent, bioaccumulative, predominantly anthropogenic and are considered toxic under Paragraph 64(a) of CEPA 1999, and as such, meet the criteria for Track I substances under Canada's Toxic Substances Management Policy. Therefore the Canadian federal government proposed that TeCBs be subjected to virtual elimination provisions of CEPA 1999. The prohibition on manufacture, use sale, offer for sale, or import of TeCBs will work towards the objective of virtual elimination.

Date of entry into force of the final regulatory action: 09/02/2007