On June 17, 2022, Canada published its draft Framework for the Risk Assessment of Manufactured Nanomaterials under the Canadian Environmental Protection Act, 1999 (CEPA) for a 60-day public comment period. The plain language summary states that the framework describes how scientists at Environment and Climate Change Canada (ECCC) and Health Canada (HC) conduct risk assessments on nanomaterials. The draft risk assessment framework outlines approaches and considerations for informing the risk assessment of nanomaterials under CEPA, including both existing nanomaterials on the Domestic Substances List (DSL) and new nanomaterials notified under the New Substances Notification Regulations (Chemicals and Polymers). A substance is assessed as a nanomaterial if it meets the criteria described in HC’s working definition for nanomaterial and particle size distribution threshold (number or mass-based), as stated in both the draft framework and the New Guidance Document for the notification and testing of new substances: chemicals and polymers. Comments are due August 16, 2022.

The framework discusses in detail the nanomaterial-specific considerations for risk assessment, including:

• The key physical and chemical properties specific for nanomaterial identification and used for grouping or classifying nanomaterials for information gathering;
• The data considerations used in a nanomaterial risk assessment, such as test data or modeling; and
• The behavior of nanomaterials throughout the life cycle of the nanomaterial (from production to disposal) and characterizing those potential effects on human health and the environment.

The framework also details the ecological and human health risk characterization of nanomaterials:

• Ecological risk characterization approach for nanomaterials: The ecological risk characterization of nanomaterials considers relevant ecological processes that may affect the potential exposure and hazardous effects of nanomaterials. This includes investigating how nanomaterials are transported in the environment and their environmental fate. In addition, ECCC scientists investigate how biotic and abiotic components can influence the bioavailability, persistence, or toxicity of a nanomaterial; and
• Human health risk characterization approach for nanomaterials: Human health risks of nanomaterials are characterized based on nanomaterial-specific hazards and exposures for relevant routes of exposure. Characterization of the risks to Canadians are based on, but not limited to, use of products available to consumers and exposure via food, drinking water, and environmental media. Special consideration is given to the potential risks to vulnerable populations (for example, children, pregnant women).

The draft framework states that the conclusions reached through the assessment process for nanomaterials under CEPA may differ between the traditional chemical form of a substance and the nanomaterial form of the same substance and may differ among different nanoscale forms of the same substance. ECCC and HC scientists use a weight-of-evidence approach to combine the multiple lines of evidence and their uncertainties to conclude if a nanomaterial reaches the environment in a quantity or concentration or under conditions that meet any of the criteria for toxicity as set out under CEPA.

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