Pentachlorobenzene

What is it?

Pentachlorobenzene is a manufactured chemical substance in the chlorine family that is found in the form of white or colourless crystals.

Where is it found and how is it used?

Pentachlorobenzene is not currently produced in Canada. At one time, it could be found in the fluids that were used to top up polychlorinated biphenyl (PCB) transformers and in dyestuff carriers. These applications have either been discontinued or are being phased out. Pentachlorobenzene is found in small amounts in the fungicide pentachloronitrobenzene (also known as quintozene), which is currently used, but not produced, in Canada. Pentachlorobenzene is present as an impurity in this fungicide and in several herbicides, pesticides and fungicides currently in use in Canada.

Pentachlorobenzene is also contained as an impurity in pentachlorophenol, a wood treatment chemical that is used in Canada. In North America, the only currently registered uses for pentachlorophenol are for pressure and thermal treatment of railway ties, utility poles, pilings and outdoor construction materials.

Pentachlorobenzene may 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 into the environment as a result of waste incineration and barrel burning of household waste.

What are its effects?

Assessments of pentachlorobenzene show that it is a persistent and bioaccumulative chemical substance that could have an immediate or long-term harmful effect on the environment and biological diversity. However, it does not appear to enter the environment in amounts large enough to affect human health.

What are we doing?

Pentachlorobenzene is considered as toxic under the Canadian Environmental Protection Act, 1999 and is on Schedule 1, List of Toxic Substances, of CEPA 1999. The Government of Canada has proposed the addition of pentachlorobenzene to the Prohibition of Certain Toxic Substances Regulations, 2005 to prohibit its manufacture, import, use, sale and offer for sale in Canada. The proposal will prevent re-introduction of the chemical substance into Canada. The regulations amending the Prohibition of Certain Toxic Substances Regulations, 2005 are expected to be issued by the end of 2006.

At the same time, users of products containing pentachlorobenzene have been taking steps to ensure that the lowest possible amounts of this chemical substance enter the environment.

Being informed is the best protection. Find out more about pentachlorobenzene and what the Government of Canada is doing by visiting Environment Canada's Management of Toxic Substances Website.

Health effects for any substance depend on the amount of exposure, and how that exposure occurs.