Categorization of the Domestic Substances List for Greatest Potential for Human Exposure

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires categorization (Section 73), of all of the approximately 23,000 substances on the Domestic Substances List (DSL) prior to a legally mandated deadline of September 14, 2006 (Government of Canada, 1999). The Proposal for Priority Setting for Existing Substances on the Domestic Substances List under the Canadian Environmental Protection Act, 1999: Greatest Potential for Human Exposure outlined the first stage of prioritization for the requirement under the legislation for Health Canada to identify (i.e., "categorize") those substances on the DSL that present the greatest potential for exposure (GPE) to Canadians. Supporting documentation to this proposal is also available.

To solicit stakeholder and public comment, this proposal was sent to a number of associations and groups of industrial stakeholders, environmental non-governmental organizations, selected Government Departments, as well as being posted on the Existing Substances Division (Health Canada) web site. Prior to the deadline for comment (March 31^st, 2004), the Existing Substances Division held an information session on March 8^th, 2004 for interested stakeholders and non-governmental groups on the content of this proposal and other human health related components of the DSL Categorization and Screening Program under CEPA 1999.

Written comments on this proposal were received from the following organizations:
Formulated Products Industry Coalition (FPIC)
Canadian Consumer Specialty Products Association (CCSPA)
Food and Consumer Products Manufacturers of Canada (FCPMC)
Flavour Manufacturers Association of Canada (FMAC)
CEPA Industry Coordinating Group (ICG)
Color Pigments Manufacturers Association, Inc. (CPMA)
Mining Association of Canada (MAC)
Dominion Colour Corporation
Canadian Environmental Network (CEN)
Office of Environmental Affairs, Natural Resources Canada (NRCan)

With the exception of those from the CPMA and MAC, comments included in the submissions from the other industrial groups were identical.

The following represents a synthesis of the comments received that were specific to the content of the proposal. From industrial stakeholders, there was general support for the overall approach to the first stage of priority setting for categorization with respect to GPE. There were also suggestions that:

• consideration of "inherently toxic" to humans be limited to cancer and genotoxicity;
• some compounds be set aside based upon "low concern" lists;
• Health Canada allow for submission of rationales by stakeholders on individual substances as a basis to "set aside" from additional consideration;
• additional information/criteria be considered in subsequent stages of priority setting for potential for exposure; and
• consideration of potential for exposure be combined with that for "inherently toxic" to humans.

Information on the composition of several pigments was also provided.

Comments from non-governmental environmental groups included a:

• desire for immediate clarity on the screening list;
• desire for a "parallel process" for children's health;
• number of technical suggestions for improving the simple GPE "too" including grouping, deleting the number of submitters, more detailed ranking of use codes with reliance on the highest or average of all values;
• suggestion to develop a list based on other factors of exposure (e.g., physical chemical properties, fate and transport, etc.);
• suggestion to consider uptake in setting priorities for exposure and to eliminate substances with known lower or no exposure risk;
• suggestion that consideration of exposure alone does not identify all substances of concern; and
• suggestion that the current legislative construct for DSL categorization does not identify all substances on the DSL that should be considered "inherently toxic" to human health (i.e., consideration of priorities for human health should not be limited to those substances identified through the persistence or bioaccumulation stream).

In addition, both industrial and non-governmental environmental groups proposed that substances included and previously assessed on the first and second Priority Substances Lists or those on the List of Toxic Substances under CEPA, not be considered additionally in priority setting in DSL categorization and screening.

Since the close of the comment period on March 31^st, 2004, representatives of the Existing Substances Division have met with the Canadian Chemical Producers Association, the CEPA Industry Coordinating Group, the Formulated Products Industry Coalition, Procter & Gamble, the Canadian Environmental Law Association, the Canadian Environmental Network, and the World Wildlife Fund Canada, to additionally clarify issues raised during the comment period regarding technical aspects of the proposal for priority setting for GPE categorization, and to outline the next steps, including the development of a proposed integrated framework for the health-related components of DSL categorization (i.e., greatest potential for human exposure and "inherently toxic" to humans).

Many of the issues raised during the comment period on the first GPE proposal are being addressed as part of this integrated framework. This framework proposes additional stages of refinement of priority setting for both exposure and effect which incorporate additional information, including several recommended in public comments on the GPE proposal (e.g., age-specific exposure estimation). It will also result in the ranking of identified prioritized substances for screening on the basis of risk to human health.

In particular, there were several comments on the first stage of priority setting for categorization which related to additional refinement of estimated exposure. Such refinement was precluded in the first stage of priority setting for GPE by the limitations of data readily available for all 23,000 DSL substances. However, a more complex exposure tool driven by use scenarios is being developed as a basis to refine exposure in subsequent stages for smaller numbers of substances considered as priorities. Development of this tool is consistent conceptually with many of the suggestions received from all stakeholders and will address exposure from both environmental media and products and take into account considerably more data than was considered for relative ranking in the first stage proposal for GPE including that on physical/chemical properties, bioavailability, use and emissions. This more complex tool will result in upper bound quantitative estimates of combined consumer and multimedia environmental exposure for various durations and age groups. In the absence of data, protective assumptions will be made that will result in the generation of conservative exposure estimates. Additionally, in response to suggestions received, further consideration is being given to alternative methods of ranking all substances on the DSL for greatest potential for exposure based on the parameters of annual quantity of use and rankings of use codes, and consideration of potential grouping of some individual substances.

In addition, as per suggestions from both industrial and non-governmental environmental groups, substances previously assessed in the Priority Substances program and those on the List of Toxic Substances will not be considered additionally in health-related priority setting for DSL categorization and screening.

It is anticipated that the proposed integrated framework, as well as a preliminary list of DSL substances prioritized for screening assessment on the basis of potential risk to human health, will be released for public comment in the fall of 2004. Prior to the release for public comment, communication materials on various elements related to the proposed integrated framework will be distributed and posted at the Existing Substances Division web site as they become available. These materials will include invitation to stakeholders to submit specified information on focussed priorities to assist in additional priority setting.

Existing Substances Division
Environmental Contaminants Bureau
July 12, 2004