On July 23, 2025, Environment and Climate Change Canada (ECCC) announced the release of the Plan of Priorities, a multi-year plan that outlines upcoming priorities for the assessment of chemical substances. The Plan includes a list of more than 30 substances and substance groups prioritized for assessment and includes new or expanded activities to help assess, control, and manage risks posed by substances. ECCC states that in selecting and prioritizing these substances, considerations included:

• Substances that are hazardous to human health and/or the environment, including carcinogens, mutagens, and reproductive toxicants, as well as endocrine disrupting substances;
• Substances that are impacting populations or environments that may be at increased risk, due to either greater exposure or greater susceptibility;
• Substances with the potential to contribute to cumulative risks;
• Very hazardous substances that are capable of long-range transport;
• Substances with known hazardous properties that are used in products available to consumers; and
• Potential substitutes for substances with known toxicity.

ECCC used the input and feedback received during the public consultation on the Proposed Plan of Priorities to help refine the current Plan. As reported in our October 8, 2024, blog item, the Proposed Plan includes nanoscale silver, nanoscale zinc oxide, nanoscale forms of nickel oxide, and nanoscale forms of titanium dioxide (nano-TiO₂). The July 2025 Plan includes nanoscale silver, nanoscale zinc oxide, and nanoscale forms of titanium dioxide. The rationales for priorities include the following information:

• Nano-TiO₂: Nano-TiO₂ was identified under the Government of Canada initiative to ensure that nanomaterials currently in commerce in Canada undergo ecological and human health risk assessment. Nano-TiO₂ has not been explicitly considered in the assessments of existing substances conducted under the Canadian Environmental Protection Act, 1999 (CEPA). Based on a 2015 information-gathering initiative and an additional 2020 follow-up to determine the commercial status of certain nanomaterials, nano-TiO₂ was found to be imported into Canada at a high volume in 2014 of >600,000 kilograms (kg). Nano-TiO₂ was reported to be used in various consumer products, including self-care products, paints and coatings, and adhesives and sealants. Nano-TiO₂ can be photoactive in the aquatic environment, causing oxidative stress and potential toxicity to aquatic organisms. Titanium dioxide is classified as a Group 2B carcinogen, “possibly carcinogenic to humans,” by the International Agency for Research on Cancer (IARC). Nano-TiO₂ may have adverse genotoxic, neurotoxicological, cardiovascular, and reproductive effects. It has also been shown to cause pulmonary damage/inflammation following inhalation exposure.
• Nanoscale silver: Nanoscale silver was identified under the Government of Canada initiative to ensure that nanomaterials currently in commerce in Canada undergo ecological and human health risk assessment. Nanoscale forms of silver have not been explicitly considered in the assessments of existing substances conducted under CEPA. Nanoscale silver is used in a wide variety of commercial and consumer products. Advances in the ability to synthesize nanoscale silver have allowed for innovation for the impregnation of nanoscale silver into common consumer products, such as athletic clothing, bedding, cosmetics, and medical equipment, often leveraging the antimicrobial properties of the substance. Additionally, nanoscale silver is useful in electrical and optical applications. There is evidence that nanoscale silver can be harmful to human health and the environment. There is high potential for human health hazard, as several studies have reported associations between exposure to silver nanoparticles and reproductive/developmental effects, and there is also evidence of neurotoxicity. In addition, preliminary findings for nanoscale silver suggest high aquatic toxicity, particularly to planktonic and bacteria species. Nanoscale silver was found to be in commerce in Canada based on a 2015 information-gathering initiative and an additional 2020 follow-up to determine the commercial status of nanomaterials.
• Nanoscale zinc oxide: Nanoscale zinc oxide was identified under the Government of Canada initiative to ensure that nanomaterials currently in commerce in Canada undergo ecological and human health risk assessment. Nanoscale forms of zinc oxide have not been explicitly considered in the assessments of existing substances conducted under CEPA. Based on a 2015 information-gathering initiative and an additional 2020 follow-up to determine the commercial status of certain nanomaterials, nanoscale zinc oxide was imported annually into Canada at a volume of 79,000 kg. Nanoscale zinc oxide was reported to be used in various consumer products, including some intended for use by or for children (for example, toys, sunscreen lotions), food packaging, drugs, and personal care products and cosmetics. There is evidence that nanoscale zinc oxide can be harmful to human health and the environment. Nanoscale zinc oxide can affect aquatic organisms due to nanoparticle effects and release of the zinc ion. For human health, there are concerns for reproductive and/or developmental toxicity following exposure to nanoscale zinc oxide, and potential hazard resulting from repeated dose oral and inhalation exposure. Additionally, nanoscale zinc oxide may exert genotoxic effects in mammalian cells.

Bill S-5, Strengthening Environmental Protection for a Healthier Canada Act, requires that the Plan of Priorities be reviewed every eight years. ECCC notes that the list of substances prioritized for assessment “may also be amended from time to time, based on, for example, the emergence of new science, or through the new public request for assessment mechanism.” ECCC will provide an opportunity to comment on amendments to the Plan.