On March 5, 2026, Environment and Climate Change Canada and Health Canada jointly released the Risk Assessment Framework for Manufactured Nanomaterials under the Canadian Environmental Protection Act (CEPA). The framework outlines the approach for assessing the risks of nanomaterials and highlights key considerations for evaluating their potential impacts on human health and the environment.
Background
Nanotechnology has applications across a wide range of industries and sectors. However, compared to conventional chemical substances, nanomaterials may exhibit unique properties and behaviors that could lead to different risks to human health and the environment. As a result, they require specialized risk assessment approaches rather than the traditional methods used for standard chemicals. On June 17, 2022, Canada published a draft version of this framework, which was open for a 60-day public consultation period before the final release.
Key Points
1. Definition of Nanomaterials (Applicable under the Canadian Environmental Protection Act)
Nanomaterials are defined as substances that:
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Have at least one external dimension within the nanoscale (1–100 nm), or contain internal or surface structures at the nanoscale; or
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Are smaller or larger than the nanoscale in all dimensions but exhibit one or more nanoscale properties or phenomena.
Specific Thresholds:
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By number: At least 10% of primary particles have one or more internal or external dimensions within the nanoscale range.
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By mass (if number distribution data is unavailable): At least 1% of primary particles fall within the nanoscale range.
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Agglomerates and aggregates are also considered nanomaterials regardless of their external size if the constituent particles meet the nanoscale definition.
2. Basic Principles (Building on Existing Regulatory Frameworks)
In line with recommendations from the Organisation for Economic Co-operation and Development, the framework adapts existing chemical regulatory approaches rather than creating entirely new regulations specifically for nanomaterials. However, risk assessments must account for the unique physicochemical properties of nanomaterials, such as size, shape, and surface chemistry. When scientific data is limited or uncertain, the framework recommends applying conservative yet realistic assumptions to ensure adequate protection of human health and the environment.
3. Legislative and Regulatory Framework for Existing and New Nanomaterials
Canada applies the regulatory framework established under the Canadian Environmental Protection Act (CEPA) to evaluate and manage potential risks of nanomaterials to human health and the environment. While the existing framework for bulk chemicals and polymers generally applies to nanomaterials, certain adjustments may be required to address nanomaterial-specific characteristics such as unique physicochemical properties and lifecycle transformation products.
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Existing nanomaterials: Environment and Climate Change Canada has collected data to develop an inventory of nanomaterials currently in commercial use in Canada and has undertaken research to evaluate nanoscale substances listed in the Domestic Substances List (DSL).
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New nanomaterials: Importers and manufacturers must submit information under the New Substances Notification Regulations (NSNR). This information is reviewed by Environment and Climate Change Canada and Health Canada to determine whether the nanomaterial meets the criteria for toxicity outlined in Section 64 of CEPA.
4. Risk Assessment Methodology for Chemicals and Polymers
Risk assessment evaluates the likelihood of adverse effects caused by a substance by considering two key elements:
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Hazard: The inherent ability of a substance to cause harmful effects.
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Exposure: The amount or concentration of a substance reaching an organism, system, or population, including the frequency, duration, and intensity of exposure.
Quantitative risk characterization uses the following metrics:
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Risk Quotient (RQ):
RQ = Predicted Environmental Concentration (PEC) / Predicted No-Effect Concentration (PNEC)
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RQ ≥ 1: Indicates potential environmental risk
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RQ < 1: Indicates low likelihood of environmental harm
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Margin of Exposure (MOE):
MOE = Critical Effect Level / Exposure Level
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Primarily used for human health risk assessment
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If the calculated MOE is lower than the target MOE, it may indicate a potential health risk.
5. Application of Uncertainty, Weight of Evidence, and Precautionary Measures
Risk assessments conducted under Canadian Environmental Protection Act incorporate the Weight of Evidence (WoE) approach and the precautionary principle to address uncertainties in scientific data.
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Weight of Evidence (WoE): Integrates multiple sources of information and scientific data to support decision-making.
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Precautionary Principle: Applies conservative yet realistic assumptions where uncertainties exist, ensuring protective decision-making.
The level of precaution applied is proportional to the degree of uncertainty. Overall, the framework emphasizes that nanomaterial risk assessment is a science-based, comprehensive process that integrates hazard and exposure analysis. By applying WoE and precautionary measures, regulators determine whether substances meet the “toxic” criteria defined under Section 64 of CEPA and whether risk management actions are necessary.
