Toxic substances list: Mirex

Dodecachloropentacyclo [,6.03,9.04,8] decane, also known as Mirex, is not known to occur in the environment as a natural product. Although the generation of Mirex by natural processes cannot be excluded, such a contribution to the levels existing in the environment is considered negligible.

Although Mirex was never registered for use as a pesticide in Canada, it has been used worldwide against fire ants, termites and other insect pests. Mirex has also been used as a fire retardant agent in plastics, rubber, paint, paper and electrical goods. The main sources of Mirex in Canada are located in New York State in the Niagara River and the Oswego River where chemical manufacturing and fire retardant production plants were located. It has entered Canada through long-range atmospheric transport and via water and sediments in the Niagara River where it was manufactured until 1976, and via loadings from the Oswego River where it was used as a flame retardant.

Mirex appears on the List of Toxic Substances (Schedule 1) of the Canadian Environmental Protection Act, 1999 (CEPA 1999), and regulated under the Mirex Regulations, 1989.

The Prohibition of Certain Toxic Substances Regulations put into one set of regulations all of the toxic substances for which it was determined that their use in Canada should be banned for reasons of environmental or health protection.

During the Regulatory Review process of the Department of the Environment, it was suggested that it would be simpler and more effective administratively to develop a generic banned-substances regulation to which substances would be scheduled rather than having separate regulations, as was the case for Mirex.

CAS (Chemical Abstracts Service) registry number: 2385-85-5

Risk assessment


This substance is entering the environment from the following sources:

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Other information


Chemicals Management Division
Environment and Climate Change Canada
Gatineau, QC K1A 0H3


Substances Management Information Line:
Telephone: 1-800-567-1999 (in Canada) or 819-938-3232
Fax: 819-938-3231


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