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Canada - Final Regulatory Action
Hexachlorobutadiene CAS number:
Date circular:

Chemical name: 1,3-Butadiene, 1,1,2,3,4,4-hexachloro-

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 HCBD, or a mixture or product containing HCBD, unless the substance is incidentally present.

Use or uses that remain allowed:

The Regulations do not apply to HCBD that is:
contained in a hazardous waste, hazardous recyclable material or non-hazardous waste;
contained in a control product (e.g., pesticide);
present as a contaminant in a chemical feedstock used in a process from which there are no releases of the substance and provided that the substance is destroyed or completely converted in that process to a substance that is not listed in Schedule 1 or 2 of the Regulations; or
used in a laboratory for analysis; in scientific research; or as a laboratory analytical standard.
The Regulations also establish a permit system that provides a mechanism for temporarily exempting certain applications of a substance listed in the Regulations. A permit may be granted only if the Minister of the Environment is satisfied that there is no technically or economically feasible alternative or substitute available for the substance. In addition, the Minister must be satisfied that measures have been taken to minimize or eliminate any harmful effects of the substance on the environment and human health. Finally, the applicant must provide an implementation plan that identifies specific timelines for eliminating the substance. Each permit lasts for 12 months, and can be renewed only twice.

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. HCBD is found on Schedule 1, which lists prohibited toxic substances subject to total prohibition, with the exception of incidental presence.

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

Summary of known hazards and risks to the environment:

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the Ministers of the Environment and of Health to prepare and publish a Priority Substances List that identifies substances, including chemicals, groups of chemicals, effluents and wastes that may be harmful to the environment or constitute a danger to human health.
The Act also requires both Ministers to assess these substances and determine whether they are "toxic" or capable of becoming "toxic" as defined in the Act, which states: "a substance is toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that
(a) have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
(b) constitute or may constitute a danger to the environment on which life depends; or
(c) constitute or may constitute a danger in Canada to human life or health."
A description of the approach to assessment of the environmental effects of Priority Substances is available in the document "Environmental Assessments of Priority Substances under the Canadian Environmental Protection Act, Guidance Manual Version 1.0 March 1997" ( It should be noted that the approach outlined in this document has evolved to incorporate recent developments in risk assessment methodology, which will be addressed in future releases.
Relevant data were identified from existing review documents, published reference texts and on-line searches conducted between January and April 1996. A list of the databases searched can be found in the Assessment Report.
A survey of Canadian industry was carried out under authority of Section 16 of the original CEPA (1988). Companies were required to provide information on uses, releases, environmental concentrations, effects or other data on HCBD that were available to them if they met the trigger quantity of 1 kg of HCBD per year. Data obtained after November 30, 1997 were not considered in the assessment unless they were critical data received during the 60-day public review of the report (July 1 to August 30, 2000).
Canadian sources of HCBD were minor at the time the Report was published, but potentially numerous and included possible releases in landfill leachates, releases during refuse combustion and releases as a by-product in the production of some chlorinated chemicals. Until shortly before the Report was published, the most significant point source of HCBD in Canada appeared to be the Cole Drain, which discharges into the St. Clair River at Sarnia, Ontario, and includes outfalls from an industrial landfill and a few industrial companies. Since 1998, the discharge from the Cole Drain has been practically eliminated. The inadvertent production and use of HCBD in the United States are other potential sources of HCBD to the Canadian environment via long-range transport through the atmosphere or transboundary movement in shared water systems.
When released into the environment, HCBD partitions somewhat to air, soil, water and sediments, but tends to remain mostly in the compartment to which it was released. HCBD is slowly removed from the atmosphere by photo-oxidation, with an estimated half-life of up to three years. Evidence for long-range transport of HCBD exists, as the substance has been detected in samples taken from various sediment depths in Great Slave Lake. HCBD biodegrades slowly in aerobic water, with an estimated half-life of up to a year, but it would persist considerably longer under anaerobic conditions. HCBD accumulates in the tissues of freshwater organisms, with a maximum reported bioconcentration factor of 19 000, but it is quite easily metabolized and there fore does not biomagnify through food chains. Available data indicate that HCBD meets the criteria for persistence and bioaccumulation according to the Persistence and Bioaccumulation Regulations of CEPA 1999.
HCBD was detected in Canadian surface waters, sediments, aquatic organisms and, occasionally, air. Concentrations of HCBD in Canadian surface water were lower than the adverse effects thresholds predicted for sensitive pelagic aquatic organisms. Concentrations of HCBD in the sediment of highly contaminated sections of the St. Clair River were high enough that sensitive benthic organisms could experience adverse effects because of their inability to move to less contaminated areas.
Based on available data, it has been concluded that HCBD is entering the environment in a quantity or concentration or under conditions that have an immediate or long-term harmful effect on the environment or its biodiversity. Therefore, HCBD is considered to be "toxic" as defined under Paragraph 64(a) of CEPA 1999.

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

HCBD is not currently used, sold, produced, imported or exported in Canada. The only way to ensure that it is not introduced into the Canadian market is through a ban. Furthermore, because HCBD meets the criteria for persistence and bioaccumulation, the Canadian federal government has proposed that HCBD be subject to virtual elimination provisions of CEPA 1999. The prohibition on manufacture, use, sale, offer for sale, or import of HCBD will work towards the objective of virtual elimination.

Date of entry into force of the final regulatory action: 15/05/2005