Overview of the Existing Substances Program: chapter 3

3. Identifying and prioritizing substances for assessment

3.1 Identifying candidates for risk assessment

In Canada there are approximately 23 000 substances on Canada's Domestic Substances List (DSL); these are referred to as "existing substances", most of which have never been assessed by the federal government for their potential risks to human health or the environment. For the Existing Substances Program to be successful it is important that assessment priorities be correctly identified and key data gaps identified at an early stage so that information required to complete an assessment is available when needed. Candidates for risk assessment under the Existing Substances Program are identified through seven main mechanisms (or "feeders") of equal importance:

• Categorization of the DSL: Under section 73 of the Canadian Environmental Protection Act, 1999 (CEPA), the Ministers of Environment and Health had to identify by September 2006 which of the 23 000 substances on the DSL, on the basis of available information, (a) may present, to individuals in Canada, the greatest potential for exposure; or (b) are persistent [take a long time to break down] or bioaccumulative [collect in living organisms], and inherently toxic to human beings or to non-human organisms. For more information on the categorization process and preliminary results please visit Environment Canada's Existing Substances website, and Health Canada's Existing Substances website.
• Industry information: Sections 70 and 71 of CEPA 1999 are information gathering provisions. Section 70 puts the onus on industries to provide information they possess that reasonably supports the conclusion that a substance is "toxic" or capable of becoming "toxic" as defined under CEPA. Section 71 allows the Minister of the Environment to require all parties engaged in activity involving a substance to provide information for the purpose of assessing whether the substance is toxic or is capable of becoming toxic, or for the purpose of assessing whether to control, or the manner in which to control a substance. This includes the authority to request existing information or to require sampling, testing and the generation of new data.
• Information exchange and review of decisions of other jurisdictions: Section 75 of CEPA requires the Minister of the Environment, to the extent possible, to cooperate and develop procedures for exchanging information on substances with other governments in Canada and member states of the Organisation for Economic Co-operation and Development (OECD). Also, decisions made by these other jurisdictions to prohibit or substantially restrict substances for environmental or health reasons are to be reviewed to determine whether the substances are "toxic" or capable of becoming "toxic" according to CEPA. For more detailed information on the proposed process for reviewing provincial, territorial or international decisions please visit Environment Canada's Existing Substances Website.
• Nominations to the Priority Substances List (PSL): Section 76 of CEPA requires the Ministers of the Environment and of Health to establish and maintain the Priority Substances List (PSL), which specifies substances to which priority should be given in assessing whether they are toxic or capable of becoming toxic. Any person may request that a substance be added to the PSL. The Ministers of the Environment and of Health determine whether nominated substances should be prioritized for assessment and added to the PSL.
• New substances notifications: The CEPA approach to the control of new substances is both proactive and preventative, employing a pre-import or pre-manufacture notification and assessment process. When this process identifies a new substance that may pose a risk to health or the environment, the Act empowers Environment Canada to intervene prior to or during the earliest stages of its introduction into Canada. The New Substances Program provides advance warning as well as knowledge of commercial chemicals that may be of concern. It also allows the Existing Substances Program to identify substances or classes of chemicals on the DSL that may have chemical properties similar to those managed under the New Substances Program. For more information on the New Substances Program please visit Environment Canada's New Substances website.
• Emerging science and monitoring: The tracking of information from emerging science and monitoring studies allows the government to identify and respond to emerging concerns. Canada is working closely with government research institutes and Canadian universities, through informal working relationships, workshops and conferences, to keep abreast of new science and environmental monitoring information that give rise to concerns.
• International assessment or data collection: Many international programs deal with the risk assessment or risk management of industrial chemicals and identify substances for which some action should be considered. These programs also promote the mutual acceptance, and shared use of data, and the development of harmonized policies for managing risks to human health and the environment. Canada actively participates in the Organisation for Economic Cooperation and Development (OECD) Chemicals Programme and has established a strong relationship with the U.S. Environmental Protection Agency's Existing Chemicals Program to exchange information on substances of concern.

3.2 Setting priorities for assessments

The number of substances identified by the categorization exercise alone renders it impossible for Canada to assess all substances simultaneously. Therefore, the program is focusing resources on those in most urgent need of assessment. The objective of setting priorities is two-fold:

• to set priorities for risk assessments and ensure that substances of greatest potential concern are addressed first; and
• to provide the risk management program with the means to effectively manage priorities, particularly in light of demanding and fluctuating departmental priorities.

The consistency with which all substances on the DSL were categorized provides the Government of Canada with a commensurate way to identify assessment and risk management priorities based on a set of established criteria. This prioritization framework is applicable to substances identified for assessment via the categorization exercise or via other mechanisms. Groups of substances that correspond to the different parameters used for categorization will be identified, and the relative hazard of individual substances can be determined by comparing overall values for each substance.

Categorization of the DSL has also provided a comprehensive overview of the level of data available to characterize existing substances in Canada. While certain substances have comprehensive data sets based on experimental data, the majority of substances have no, or a very limited amount of experimental data. It is critical to take data availability into consideration so appropriate next steps can be identified.

The Chemicals Management Plan, announced in December 2006, outlines how the Government of Canada will address certain substances identified as priorities for action and will implement a series of measures regarding these substances to further protect the health of Canadians and the environment from the potential effects associated with exposure to these substances. These measures will:

• Improve, where possible, persistence and/or bioaccumulation information;
• Help to identify industrial best practices in order to set benchmarks for risk management, product stewardship, and virtual elimination; and
• Help to collect environmental release, exposure, substance and/or product use information.

In so doing, timely risk assessment and management interventions will be carried out to minimize the risk of serious or irreversible harm associated with certain chemicals.

More information is available on the Chemicals Management Plan.