Butanone oxime - information sheet

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

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  • The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA 1999) to determine whether they present or may present a risk to human health or to the environment.
    • The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent of exposure to people or the environment.
    • When needed, the Government implements risk management measures under CEPA 1999 and other federal acts to help prevent or reduce potential harm.
  • The Government concluded that butanone oxime is harmful to human health, but not to the environment, at levels of exposure considered in the assessment. The concern for human health was due to potential exposure from the use of certain products, such as alkyd paints and coatings. This substance is associated with the potential to cause cancer, as well as having adverse effects on organs and nose tissue. A code of practice (risk management tool) was published in 2014 to help reduce the exposure of concern.
  • A performance measurement evaluation of the risk management actions taken for butanone oxime concluded that health risks were not effectively managed. Therefore, the Government published a consultation on proposed new risk management actions for butanone oxime in certain products available to consumers on July 15, 2022.

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 Chemicals Management Plan (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.

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.
  • 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

  • Butanone oxime was added to Schedule 1 to CEPA 1999, also called the List of Toxic Substances. Adding a substance to the list does not restrict its use, manufacture or import. Rather, it enables the Government to take risk management actions under CEPA 1999.
  • Proposed Risk Management Approach for 2-Butanone, oxime (butanone oxime) was published on March 6, 2010, and had a 60-day public comment period.
  • In June 2014, a Code of Practice for butanone oxime was published to help reduce inhalation exposure of the general population to the substance during and immediately following indoor use of consumer alkyd paint and coating products.
  • In May 2019, Health Canada gathered information to inform the evaluation of progress achieved in reducing inhalation exposure of the general population to butanone oxime by the code of practice.

Performance measurement

Where to find updates on risk management actions

Related information

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