Existing Substances

Health Canada is responsible for the assessment of potential risks to human health posed by existing substances in Canada under the Canadian Environmental Protection Act, 1999 (CEPA 1999). The Existing Substances Division (ExSD) conducts this work within Health Canada. ExSD works jointly with Environment Canada, the department responsible for assessing the risks of existing substances to the environment. Existing substances include those on the Domestic Substances List (DSL). The DSL is a compilation of about 23 000 substances used, imported or manufactured in Canada for commercial purposes between January 1, 1984, and December 31, 1986, at a quantity of greater than 100 kg per year; substances that are not listed on the DSL are considered to be new to Canada.

The Chemical Substances Portal - chemicalsubstances.gc.ca

CEPA 1999 provides the framework for the identification, prioritization and assessment of existing substances and for the control or management of those considered to pose a risk. This framework is broad, open, transparent and evidence-based, taking into account aspects (i.e., exposure and effects) of a substance related to the potential risk it may pose, and it builds upon work done in other jurisdictions.

The three principal phases of identification and assessment of priorities for risk management of existing substances specified under CEPA 1999 are categorization, screening assessment and in-depth Priority Substances List (PSL) assessment. One objective of the latter two phases, namely screening and full assessment, is to determine whether a substance is CEPA-toxic as defined in Section 64 of the Act, which may then set the stage for addition of the substance to Schedule 1 (the List of Toxic Substances) of the Act and for reviewing options for controlling risks to human health and/or the environment.

Information available

In this section, you will find information regarding:

  • Categorization of the Domestic Substances List;
  • Screening Health Assessment of Existing Substances;
  • Health risk assessment of Priority Substances;
  • Information on how to join our mailing list to keep you updated on any new activities and publications


To view all of the Existing Substances Division documents, please see our Reports and Publications page.

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