DIDA SNAc proposal and manganese assessment

Summary#

This Canada Gazette posting from the Department of the Environment corrects an earlier notice and announces two environmental items open for comment. It republishes a proposal to add special notification rules for hexanedioic acid, diisodecyl ester (DIDA) to the Domestic Substances List and publishes a draft assessment that proposes adding manganese and its compounds to the list of toxic substances under the Canadian Environmental Protection Act, 1999. Public comment periods run from October 25, 2025 to December 24, 2025.

What it does#

• Corrects an earlier notice to confirm the availability (as of October 24, 2025) of the “Agreement on the Equivalency of Federal and Alberta Regulations Respecting the Release of Methane from the Oil and Gas Sector in Alberta, 2025.”
• Proposes to amend the Domestic Substances List so that the Significant New Activity (SNAc) rules apply to hexanedioic acid, diisodecyl ester (CAS RN 27178-16-1). If adopted, the proposal would:
  • Require companies to notify the government at least 90 days before starting certain new uses or imports.
  • Target uses in consumer products, cosmetics, natural health products and non-prescription drugs when the substance is present above specified concentration thresholds (examples: 84%, 15%, 10%, 5%, 0.2% by weight).
  • Require notification for importation when a person imports more than 10 kg of the substance in covered products in a calendar year.
• Publishes a draft assessment of manganese and its compounds that:
  • Proposes the ministers recommend adding manganese substances to Part 2 of Schedule 1 of CEPA (indicating they meet the Act’s criteria for concern).
  • Releases a risk-management scope document to start talks with stakeholders.
  • Summarizes evidence that some industrial releases, drinking-water exceedances, and certain consumer product exposures could pose environmental or human-health risks, especially for infants and young children.

Who's affected#

• Manufacturers, importers, distributors, and retailers of products that contain DIDA — notably makers/importers of lubricants, cosmetics, natural health products and non-prescription drugs.
• Businesses that would import more than 10 kg per year of DIDA in covered products.
• Industrial sectors linked to manganese releases: metal ore mining, steel and ferroalloy production, pulp and paper, wastewater treatment and related manufacturing sectors.
• Communities near industrial facilities and some First Nations communities where drinking-water manganese levels were reported above guideline levels.
• Vulnerable people: infants, very young children, pregnant people — the draft assessment highlights neurodevelopment as a key health concern.

Why it matters#

• If the DIDA SNAc rules are adopted, companies would have to tell the government in advance about many new uses or imports. That could slow or change how the substance is used in consumer goods and drugs, and give regulators time to assess health or environmental risks before new uses begin.
• The draft conclusion that manganese and its compounds meet CEPA’s criteria could lead to new controls, monitoring, or cleanup actions. That matters because manganese is common in food and the environment but high exposures — especially in drinking water or air near certain industries — can affect brain development in infants and young children.
• Both items are at consultation stages. People and businesses can read the assessment texts and submit comments during the stated comment period (October 25, 2025 to December 24, 2025).