DIDA SNAc Proposal and Manganese Assessment

Summary#

This Canada Gazette entry from the Department of the Environment contains three environment-related notices: an erratum about a methane equivalency agreement with Alberta, a proposal to require advance notifications for new uses of the chemical hexanedioic acid, diisodecyl ester (DIDA), and a draft assessment that proposes adding manganese and its compounds to Part 2 of Schedule 1 of the Canadian Environmental Protection Act, 1999. Each item affects different groups and opens or restates public comment opportunities through December 24, 2025.

What it does#

• Corrects an earlier notice to say the Agreement on Equivalency respecting methane releases from Alberta’s oil and gas sector is available as of October 24, 2025 on the CEPA registry.
• Proposes an amendment to the Domestic Substances List to apply Significant New Activity (SNAc) rules to the substance hexanedioic acid, diisodecyl ester (DIDA), CAS RN 27178-16-1:
  • Would require anyone planning certain new uses or imports to notify the government at least 90 days before starting.
  • Targets uses in consumer products, cosmetics, natural health products and non-prescription drugs with concentration thresholds such as >84%, >15%, ≥0.2%, >10%, and >5% by weight depending on the product type.
  • Would require notification if total imports in covered products by one person exceed 10 kg in a calendar year (for many product types).
  • Exempts research-and-development, site-limited intermediates, and export-only uses.
  • Public comment period runs from October 25, 2025 to December 24, 2025.
• Publishes a draft assessment of manganese and its compounds and proposes to recommend adding them to Part 2 of Schedule 1 of CEPA:
  • Concludes there is ecological risk from some releases and potential human health risk (especially for fetuses, infants and young children).
  • Releases a risk management scope document to start discussions with stakeholders.
  • Public comment period runs from October 25, 2025 to December 24, 2025.

Who's affected#

• Companies that make, import or sell products containing DIDA—especially makers of:
  • consumer products and lubricants,
  • cosmetics (including lip liners),
  • natural health products (including some facial cleansers),
  • non-prescription drugs.
• Importers who bring in products containing DIDA and may exceed the 10 kg threshold in a year.
• Researchers and manufacturers who use DIDA only for R&D or as a site-limited intermediate (these are generally exempt).
• Industries that make or release manganese or manganese-containing compounds, including mining, steel and related industrial sectors, wastewater facilities and manufacturers that use manganese in products.
• Communities and groups near industrial facilities, and vulnerable people such as infants, young children, and some First Nations communities where drinking water showed higher manganese levels.
• The Department of Health and regulators and any stakeholders who want to comment on the proposals.

Why it matters#

• If the DIDA proposal is finalized, businesses would have to tell the government before starting many new uses or imports. That can change product formulation choices, supply chains, and market plans.
• The manganese assessment signals possible future controls. Adding manganese to Schedule 1 could lead to regulations or other measures to reduce releases to air, water and products. That could affect industrial emissions, product composition, and local water quality efforts.
• The notices open a window for industry, communities and the public to provide information and shape how the government manages these substances. The deadline to comment on the DIDA and manganese notices is December 24, 2025.