On May 16, 2026, Environment and Climate Change Canada and Health Canada published an assessment of ten ketone substances on the Domestic Substances List (DSL) under the Canadian Environmental Protection Act, 1999 (CEPA) in the Canada Gazette. Among them, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) were determined to pose risks to human health and designated as "toxic substances" under paragraph 64(c) of CEPA. The government proposes to list them in Part 2 of Schedule 1 of CEPA.
Key Assessment Conclusions
|
Substance |
Conclusion |
Proposed Measures |
|
Methyl ethyl ketone (MEK) |
Meets the criteria under section 64 of CEPA; poses a danger to human health |
Proposed listing in Part 2 of Schedule 1; proposed restrictions on use in consumer products |
| Methyl isobutyl ketone (MIBK) CAS RN: 108-10-1 |
Meets the criteria under section 64 of CEPA; poses a danger to human health |
Same as above; classified by IARC as Group 2B "possibly carcinogenic to humans" |
|
2,4-Pentanedione (2,4-PD) |
Current exposure levels not dangerous, but potential toxicity risk exists |
Proposed inclusion on the "watch list" for substances that may become toxic; subsequent tracking and monitoring |
|
Remaining 7 substances (MPK, MIAK, DAA, diacetyl, 2,3-PD, acetoin, mesityl oxide / isopropylidene acetone) |
Do not meet any criteria under section 64 of CEPA |
No further action proposed at this time |
Primary Risks of MEK and MIBK
The risks primarily arise from inhalation exposure in consumer DIY products, including:
- Paint/coating removers and paint strippers
- Adhesive removers and degreasers
- Paint/coating thinners and liquid paints
- Spray products (e.g., spray paints) and wood lacquers
Proposed Control Measures
- Development of new regulatory restrictions to reduce inhalation exposure levels to MEK and MIBK in the above consumer products
- Requirements for industry to provide: current use volumes, concentration data, potential substitute substances, and socioeconomic and technical barriers and benefits
Public Comment Period
The public comment period closes on July 15, 2026. Interested parties may submit comments via:
- Email: substances@ec.gc.ca
- Online system: Environment and Climate Change Canada Single Window
