Categorization was required by the Canadian Environmental Protection Act, 1999 (CEPA 1999) and is a first step to finding out which of these chemical substances require further attention in the form of assessment, research and/or measures to control their use or release. This task was completed by September 2006, as required by the act.
Using information from Canadian industry, academic research and other countries, Government of Canada scientists worked with partners in applying a set of rigorous tools to the 23,000 chemical substances on the Domestic Substances List (DSL). They were categorized to identify those that were:
Inherently toxic to humans or to the environment and that might be:
- Persistent (take a very long time to break down), and/or
- Bioaccumulative (collect in living organisms and end up in the food chain)
Substances to which people might have greatest potential for exposure.
Through categorization, the Government of Canada identified approximately 4,000 of the 23,000 chemical substances on the DSL as meeting the criteria for further attention.