Canada Adds 2,4-Pentanedione to CEPA Watch List; MEK and MIBK Face Proposed Controls OG Title

Companies managing broader market access obligations should separately assess whether Canada's new substance notification requirements under CEPA apply. The New Substances Notification framework and the Watch List are distinct regulatory mechanisms.

What Changed Under Canada's Ketones Group Assessment?

The final Ketones Group assessment evaluated ten ketones used in industrial applications and products such as paints, coatings, adhesives, cosmetics, natural health products and food-related applications.

The principal outcomes are summarized below.

None of the ten ketones was concluded to be causing ecological harm at current exposure levels.

What Does Inclusion on the CEPA Watch List Mean?

The Watch List was introduced through section 75.1 of CEPA following amendments that entered into force in June 2023. It is intended to identify substances that do not currently meet the CEPA criteria for toxicity but may become a concern if their hazards, uses or exposure patterns change.

According to the Government of Canada's Watch List Approach, the list is a communication and transparency mechanism. It is not itself a regulatory instrument and does not impose new requirements or restrictions.

Potential follow-up activities may include:

• Tracking changes in commercial use or import volumes;

• Identifying new applications or exposure routes;

• Issuing information-gathering notices under section 71 of CEPA;

• Considering Significant New Activity provisions where appropriate; or

• Conducting environmental monitoring or biomonitoring.

These are possible future actions rather than automatic consequences of a Watch List entry.

Why Was 2,4-PD Added to the Watch List?

Canada's 2019 draft assessment initially identified a potential human health concern for 2,4-PD based on its reported presence in a limited number of consumer products.

Further investigation found that 2,4-PD was not currently available in products available to consumers in Canada. The final assessment therefore concluded that it does not pose a risk to human health or the environment at current exposure levels.

However, 2,4-PD is associated with effects of concern. The government determined that increased use or new exposure routes could change its risk profile, supporting its inclusion on the Watch List.

Companies using or supplying 2,4-PD should therefore distinguish between its current legal status and its potential future regulatory relevance: the substance is not currently restricted through the Watch List, but changes in commercial use may attract additional regulatory attention.

What Is Proposed for MEK and MIBK?

The final assessment concluded that MEK and MIBK may pose risks to human health through inhalation exposure during the use of certain products available to consumers.

The applications identified in the government's proposed risk management approach include:

• Paint or coating removers and strippers;

• Adhesive removers;

• Degreasers;

• Paint or coating thinners;

• Liquid paints;

• Spray products, including spray paints; and

• Wood lacquers.

The government intends to recommend that MEK and MIBK be added to Part 2 of Schedule 1 to CEPA. Such an addition would enable the government to develop enforceable risk management instruments.

Importantly, addition to Schedule 1 does not by itself prohibit or restrict the use, manufacture or import of a substance. Specific obligations would arise only through subsequent regulations or other risk management instruments.

The government is currently considering the development of regulatory controls to reduce inhalation exposure from the identified consumer product applications. The official documents do not yet establish:

• Substance-specific concentration limits;

• Mandatory warning or ventilation labels;

• Final product exemptions;

• Transitional periods; or

• An effective date for future controls.

The 60-day public comment period on the proposed risk management approach ended on July 15, 2026. Information collected on product concentrations, quantities, alternatives and technical or economic barriers will inform the selection and design of future measures.

What Should Companies Do Now?

For companies handling 2,4-PD

The Watch List entry does not create an immediate restriction. Nevertheless, manufacturers, importers and downstream users may consider taking the following preparatory steps:

• Document Canadian uses, annual quantities and relevant product categories;

• Identify whether 2,4-PD is present in products available to consumers;

• Monitor future section 71 notices or Significant New Activity developments;

• Review planned new applications that could increase consumer or environmental exposure; and

• Maintain communication with Canadian customers and importers regarding changes in use.

For companies handling MEK or MIBK

Companies supplying products to Canada should begin assessing their potential exposure to future risk management measures:

1. Screen formulations and supply chains. Identify products containing MEK or MIBK by CAS RN, concentration, product type and intended use.

2. Prioritize consumer product applications. Pay particular attention to paints, coatings, removers, degreasers, thinners, sprays, adhesives and wood lacquers.

3. Collect supporting information. Maintain data on annual quantities, concentration ranges, customer applications and existing exposure controls.

4. Assess alternatives. Evaluate technically and commercially feasible substitutes without assuming that immediate substitution is already mandatory.

5. Monitor the Canada Gazette. Track the proposed Schedule 1 order and any subsequent regulatory instrument, including its scope, thresholds, exemptions and transition arrangements.

Companies should avoid treating the May 2026 risk management approach as a final regulation. The design of the future control instrument may change as the government considers stakeholder submissions and other evidence.

What Happens Next?

For 2,4-PD, the immediate next step is regulatory monitoring. Canada may use future information information-gathering or monitoring initiatives to determine whether commercial uses or exposure levels are changing.

For MEK and MIBK, the government will consider information received during the public comment period and continue developing its risk management approach. The official document indicates that, once the ministerial recommendation is made, a proposed instrument would generally be required within 24 months and finalized within 18 months after the proposal, unless an applicable CEPA exception applies.

No specific date has yet been announced for the Schedule 1 addition or the introduction of detailed controls.

How Can REACH24H Support?

REACH24H supports chemical manufacturers, importers, formulators and product suppliers with:

• Substance and product applicability assessments;

• Formulation and supply chain screening;

• Canadian regulatory monitoring;

• Data-gap and compliance-readiness reviews;

• Regulatory impact assessments; and

• Substitution and risk management planning.

For further support, companies may consult REACH24H's global chemical compliance services or contact our team to assess how the latest Canadian developments may affect products containing 2,4-PD, MEK or MIBK.

Recommended Reading

• Canada's New Substance Notification Under CEPA

• Canada Publishes 2025 Prohibition of Certain Toxic Substances Regulations

• Global Chemical Compliance and Consulting

Official Resources

• Health Canada: Ketones Group

• Government of Canada: Final Assessment for the Ketones Group

• Environment and Climate Change Canada: CEPA Watch List

• Government of Canada: CEPA Watch List Approach

• Government of Canada: Risk Management Approach for Ketones