Canadian Environmental Protection Act (CEPA) - Environmental Registry - Domestic Substances List (DSL)
The Domestic Substances List (DSL) is a list of substances that, between January 1, 1984 and...

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The Domestic Substances List (DSL) is a list of substances that, between January 1, 1984 and December 31, 1986 were in Canadian commerce; used for manufacturing purposes; or manufactured in or imported to Canada in a quantity of 100 kilograms or more in any calendar year. The DSL contains approximately 23,000 substances. It is amended regularly to include additional substances that have been deemed eligible following their assessment under the New Substances Notification Regulations.

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires that existing substances be sorted or "categorized" by the Government of Canada to determine which need further attention. Categorization is the first step in scientifically assessing all chemical substances on the DSL.

Using information from Canadian industry, academic research and other countries, Government of Canada scientists at Health Canada and Environment Canada worked with partners in applying a set of rigorous tools to each of the approximately 23 000 chemical substances on the DSL. In September 2006, Canada completed this scientific evaluation or "categorization" exercise. The information from categorization is now available and is being used to focus attention on those chemical substances of highest priority for assessment or further research, and those in need of controls to protect human health and the environment.

Under the Canadian Environmental Protection Act 1999 (CEPA 1999), Environment Canada's Existing Substances Program ( is responsible for categorizing DSL substances to identify those that are suspected to be either:

  • Persistent (P): chemical substances that take a very long time to break down in the environment - sometimes many years. These substances can affect the environment for a long period of time. Because they last for so long, they can travel long distances and pollute a much wider area than those that break down quickly. OR
  • Bioaccumulative (B): chemical substances that can be stored in the organs, fat cells or blood of living organisms and remain for a long time. Over time, concentrations can build up and reach very high levels, and can also be transferred up the food chain.
  • AND Inherently Toxic to the Environment (iTE): chemical substances that are known or suspected, through laboratory and other studies, to have a harmful effect on wildlife and the natural environment on which it depends. OR
  • Inherently Toxic to Humans (iTH): these are chemical substances that are known or suspected of having harmful effects on humans. Substances were examined for a number of human health effects, including cancer, birth defects and damage to genetic material.

Chemical substances that can potentially affect human health were also placed in a priority sequence so the Government of Canada can first deal with those suspected of presenting the highest hazard and greatest potential for exposure.

Pharos lists those substances identified as PB & aquatic (environment) toxicants, PB & human toxicants, Persistent only, Bioaccumulative only, and aquatic (environment) only toxicants.

Under CEPA 1999, the Existing Substances Program at Health Canada ( is also responsible for identifying substances that have the Greatest Potential for Exposure and are Inherently Toxic to Humans.

a. Greatest Potential for Exposure (GPE): when assessing human exposure to chemical substances, scientists look at more than persistence and bioaccumulation. Some shorter-lived substances might affect humans just as much as persistent ones. To get the complete picture, scientists look at how a substance is used. Health Canada identified those chemical substances on the DSL to which people are expected most likely to be exposed. This is not yet captured by Pharos.

Environment Canada & Health Canada (EC)