Toxic substances list: pentachlorobenzene (QCB)

Pentachlorobenzene (QCB) is not currently produced or used in its pure form in Canada, and currently there is no domestic commercial demand for this substance. QCB is present as an impurity in several pesticides (herbicides and fungicides) currently in use in Canada. QCB is also contained as an impurity in pentachlorophenol, one of the main wood treatment pesticides that are used in Canada, also regulated under the Pest Control Products Act. In North America, the main use  for pentachlorophenol is for pressure or thermal treatment of utility poles,

QCBs may also be generated when organic compounds are burned or exposed to a large source of energy in the presence of a chlorine source. Through this mechanism, they may be formed and released to the environment as a result of waste incineration and barrel burning of household waste. Formerly, they could be found in dielectric fluids used to top up polychlorinated biphenyl (PCB) transformers and in dyestuff carriers. These applications have either been discontinued (dye carriers) or are being phased out (dielectric fluids). A possible source of release may include dielectric PCB material still in use.

CAS (Chemical Abstracts Service) registry number: 608-93-5

For more information on this substance, please visit the Chemical Substances website.

Risk assessment

• CEPA Schedule 1 - List of Toxic Substances - This substance has been added to the List of Toxic Substances. It is entering or may enter the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity.
• Virtual elimination of the substance (Track 1) under the Toxic Substances Management Policy
• Order Adding Toxic Substances to Schedule 1 to the Canadian Environmental Protection Act, 1999 (page 162)(September 2005)
• Priority Substance List Assessment Report

Sources

This substance is entering the environment from the following sources:

• Incineration
• Wood Preservation Sector

Risk management strategy

Click on the following link to view strategies and actions recommended to manage risks associated with the substance:

• Risk Management Strategy for Pentachlorobenzene (QCB) and Tetrachlorobenzenes (TeCBs)

Risk management tools

Tools developed to manage risks associated with the substance:

• Prohibition of Certain Toxic Substances Regulations, 2012

Consultation

Consultation (past and present) on the substance:

• Draft of the Update to the National Implementation Plan under the Stockholm Convention on Persistent Organic Pollutants (POPs) for public comment
• Response to Comments Resulting from the Public Consultation on the Proposed Regulations Amending the Prohibition of Certain Toxic Substances Regulations, 2005 (2-Methoxyethanol, Pentachlorobenzene and Tetrachlorobenzenes)
• Proposed Risk Management Strategy for Pentachlorobezene and Tetrachlorobenzenes (archived consultation document)
• Proposed Regulations Amending the Prohibition of Certain Toxic Substances Regulations, 2005 (2-Methoxyethanol, Pentachlorobenzene and Tetrachlorobenzenes)
• Publication of results of investigations and recommendations for the substances 1,2 Dichlorobenzene, 1,4 Dichlorobenzene, Trichlorobenzenes, Tetrachlorobenzenes and Pentachlorobenzene (Comment period: 2002-09-28 - 2002-11-27)
• Proposed notice requiring the preparation and implementation of pollution prevention plans in respect of inorganic arsenic compounds, hexavalent chromium compounds, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and/or hexachlorobenzene used by wood preservation facilities (Active Consultation Document until 2005-07-14)
• Notice (DRAFT) requiring the preparation and implementation of pollution prevention plans in respect of inorganic arsenic compounds, hexavalent chromium compounds, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and/or hexachlorobenzene used by wood preservation facilities
• Response to Comments on the Proposed Notice Requiring the Preparation and Implementation of Pollution Prevention Plans in Respect of Inorganic Arsenic Compounds, Hexavalent Chromium Compounds, Polychlorinated Dibenzodioxins, Polychlorinated Dibenzofurans and/or Hexachlorobenzene used by Wood Preservation Facilities

Other information

• Determination of Level of Quantification (LoQ) for Measuring Chlorobenzenes in Chlorinated Solvents
• Determination of Level of Quantification (LoQ) for Measuring Chlorobenzenes in Stack Emissions
• Canada-wide Standards for Dioxins and Furans (PDF; 69.4 KB)
• Great Lakes Binational Toxics Strategy