Butanone oxime - information sheet

2-Butanone, oxime
CAS Registry Number 96-29-7

Updated July 21, 2020:

The Final Screening Assessment for 2-Butanone, oxime (Butanone Oxime) was published on March 6, 2010, under the Challenge initiative of the Chemicals Management Plan (CMP). The assessment is summarized in this information sheet. The section entitled "Preventive actions and reducing risk" communicates updates in risk management activities, namely:

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  • The Government of Canada conducted a science-based evaluation, called a screening assessment , to address the potential for harm to Canadians and to the environment from butanone oxime.
  • Under the Canadian Environmental Protection Act, 1999 (CEPA 1999), the risk posed by a substance is determined by considering both its hazardous properties (its potential to cause adverse human health or ecological effects) and the amount of exposure there is to people and the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending upon the level of exposure.
  • As a result of the screening assessment, the Government concluded that butanone oxime is harmful to human health, but not to the environment at levels of exposure considered in the assessment.

About this substance

  • The screening assessment focused on the substance 2-butanone, oxime, also referred to as butanone oxime or MEKO. This substance was assessed as part of Batch 7 of the Challenge initiative of the CMP.
  • Butanone oxime does not occur naturally.
  • According to information gathered by the Government, at the time of the assessment, butanone oxime was used as an anti-skinning agent (used to prevent skin formation on the surface of stored products), in the formulation of alkyd paints (resin used in paints and in moulds for casting), varnishes, stains, and coatings.
  • It was also found in a number of pesticide products, namely wood preservatives and antifouling marine paints, and in some adhesives, silicone sealants, and printing inks. Butanone oxime was also used as a corrosion inhibitor (used to prevent corrosion) in industrial boilers and water treatment systems, as well as in the manufacturing process of urethane polymers.

Human and ecological exposures

  • The assessment indicated that Canadians may be exposed to butanone oxime from products available to consumers, mainly from the use of interior and dual-use (interior/exterior) alkyd paint products.
  • Exposure of the environment to butanone oxime may occur through industrial releases through wastewater treatment systems.

Key health and ecological effects (hazard)

  • At the time of the assessment, the important or critical effects used for characterizing the risk to human health from butanone oxime were potential carcinogenicity, adverse effects on organs, and adverse effects on nose tissue.
  • Butanone oxime was considered to have a low to moderate potential to cause ecological effects.

Risk assessment outcomes

  • Based upon a comparison of levels to which Canadians may be exposed to butanone oxime and levels associated with health effects, it was determined that butanone oxime may pose a risk to human health.
  • Considering all the information presented in the ecological assessment, it was determined that butanone oxime does not pose a risk to the environment.
  • The Government of Canada published the Final Screening Assessment for 2-Butanone, oxime (butanone oxime) on March 6, 2010.

Screening assessment conclusions

  • The Government concluded that butanone oxime is harmful to human health at levels of exposure considered in the assessment.
  • The Government also concluded that butanone oxime is not entering the environment at levels that are harmful to the environment.
  • Also, butanone oxime was determined to meet the persistence criteria, but not the bioaccumulation criteria, as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.

Preventive actions and reducing risk

Performance measurement

  • The Government conducts performance measurement on the risk management of substances that are concluded to be harmful to human health and/or the environment under CEPA 1999. This is done to determine whether actions taken to help protect Canadians and their environment are meaningful and effective over time.
  • On July 21, 2020, the Government published a Performance Measurement Evaluation for Risk Management of 2-Butanone, oxime (Butanone oxime). The evaluation concluded that the health risks from butanone oxime are not effectively managed at this time because concentrations of butanone oxime in consumer interior alkyd paints and coatings were not sufficiently reduced, and increased in some products.
  • Moving forward, to help ensure that risk management and human health objectives are met, the Government will consider how improvements to the strategy to manage risks can be made since the objectives were not met using the existing tool.
  • In the interim, industry is encouraged to work toward adopting the recommended practices in the code and any other strategies to reduce consumer exposure to butanone oxime.

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