News Details

On May 16, 2026, Health Canada and Environment and Climate Change Canada published the final screening assessment for a group of ten ketone substances under the federal Chemicals Management Plan (CMP). The assessment was published in the Canada Gazette, Part I (Vol. 160, No. 20), marking a significant milestone in Canada's ongoing effort to evaluate the risks posed by industrial and consumer chemicals. 

Ketones Assessed under CMP 

Ketones are a class of organic compounds that are used extensively in manufacturing, food production, and consumer products. The ten substances examined in this assessment span a broad range of industrial applications, from paint thinners and solvents to food flavoring agents. 

The government's review focused on whether these chemicals meet the hazard criteria outlined in Section 64 of the Canadian Environmental Protection Act, 1999 (CEPA), which classifies substances as toxic if they pose a risk to human health or the environment. 

Regulatory Outcomes 

MEK and MIBK: Proposed Risk Management Measures:  

Two substances, methyl ethyl ketone (MEK) which is a common industrial solvent and methyl isobutyl ketone (MIBK) which is used in lacquers, adhesives, and surface coatings, were found to meet one or more of the Section 64 criteria. As a result, the government has published a Proposed Risk Management Approach for both substances, which is now open for a 60-day public comment period beginning May 16, 2026. 

Stakeholders in the chemical manufacturing, coatings and consumer products industries are encouraged to review and respond to the proposed measures during this window. 

MPK, MIAK and MO: No Action Required 

Three substances in the group, namely methyl propyl ketone (MPK), methyl isoamyl ketone (MIAK), and mesityl oxide (MO), were assessed and found not to meet the Section 64 criteria. No further regulatory action is currently planned for these substances. 

2,4-Pentanedione Proposed for Watch List 

Although 2,4-pentanedione (2,4-PD) does not currently pose a risk to human health or the environment at existing exposure levels, the assessment identified effects of concern associated with the substance. Regulators determined that a rise in exposure could significantly alter the risk profile. 

Consequently, 2,4-PD is being proposed for addition to Canada's Watch List, a precautionary mechanism that allows authorities to monitor commercial usage and detect new or emerging sources of exposure before they become hazardous. 

Earlier draft assessments had flagged 2,4-PD as a potential concern due to its presence in consumer products. However, follow-up investigations confirmed that the substance is no longer found in products available to consumers, leading to the final "does not meet" conclusion under current conditions. 

Diacetyl, Acetoin, 2,3-Pentanedione, and Diacetone Alcohol — Pending or No Concern 

Several other substances in the group, including diacetyl, acetoin, and 2,3-pentanedione (flavoring agents commonly associated with the food and vaping industries), are still under consideration. Outcomes and follow-up plans are yet to be determined. 

Information Gathering for MEK and MIBK Still Ongoing 

A formal information-gathering notice under Section 71 of CEPA was published in June 2023 for both MEK and MIBK. This notice requires companies that manufacture, import, or use these substances to submit relevant data to support the government's risk management decisions. More details are available on Health Canada's Chemicals Management Plan web page. 

Implications for Industry 

The CMP is one of the world's most comprehensive chemical review programs. Final assessments under this plan directly inform product regulations, workplace safety standards, and environmental policies. Companies handling MEK or MIBK should closely monitor the outcome of the risk management consultation, as binding regulatory measures may follow. 

For consumers, the key takeaway is that most ketone substances reviewed pose no current risk at typical exposure levels, except for MEK and MIBK, for which targeted risk management is being actively developed. 

How to Submit Public Comments 

Organizations and individuals wishing to comment on the Proposed Risk Management Approach for MEK and MIBK, or on the proposed addition of 2,4-PD to the Watch List, should do so within 60 days of May 16, 2026. 

CAS Registry Numbers for Referenced Substances