Decenes Group - information sheet

1-Decene, dimer, hydrogenated (hydrogenated didecene)
CAS Registry Number 68649-11-6

1-Decene, tetramer, mixed with 1-decene trimer, hydrogenated (HTTD)
CAS Registry Number 68649-12-7

Publications summarized:

• Final Assessment for the Decenes Group (published on November 22, 2025. Public comments received on the draft screening assessment and risk management scope were considered and a summary of the comments with Government responses was published.
• Risk Management Approach for the Decenes Group (published on November 22, 2025 for a 60-day public comment period ending on January 21, 2026).
• Associated notice: Canada Gazette, Part I: Vol. 161, No. 47 – November 22, 2025.

On this page

• Overview
• About these substances
• Human and ecological exposures
• Key health and ecological effects (hazard)
• Consideration of subpopulations who may have greater susceptibility or greater exposure
• Risk assessment outcomes
  • Assessment conclusions
• Preventive actions and risk reduction
  • Where to find updates on risk management actions
• Related resources

Overview

• The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA) 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 to which people or the environment are exposed.
  • When needed, the Government applies risk management instruments under CEPA and other federal acts to help prevent or reduce potential harm.
• The Government concluded that substances in the Decenes Group are harmful to human health due to potential exposure from the use of cleaner/lubricant/preservative (CLP) spray products for firearm maintenance, which may cause critical lung effects when inhaled.
  • Risk management actions are proposed to help reduce exposure to these substances from CLP spray products for firearm maintenance.
• The ecological hazard and exposure potentials of the 2 substances in the Decenes Group were classified using the Ecological Risk Classification of Organic Substances (ERC) Approach. The Government concluded that substances in the Decenes Group are not harmful to the environment, at levels of exposure considered in the assessment.

About these substances

• The screening assessment summarized here focuses on 2 substances, hydrogenated didecene and HTTD, referred to collectively as the Decenes Group under the Chemicals Management Plan (CMP). 
• The substances in the Decenes Group do not occur naturally.
• According to information gathered by the Government, these substances are used in Canada in lubricants and greases (such as gear oil, transmission oil and firearm maintenance sprays).
• Hydrogenated didecene is also used in cosmetics (including lipsticks, moisturizers and cleansers) and in mining applications.

Human and ecological exposures

• The assessment indicated that people in Canada may be exposed to hydrogenated didecene and HTTD mainly through the use of certain products available to consumers. Contact with these substances may occur through the following routes:
  • oral ingestion from the use of lipsticks
  • dermal (skin contact) from the use of cosmetics and automotive products
  • inhalation (breathing in) from the use of CLP spray products for firearm maintenance
• According to the information considered under the ERC Approach, hydrogenated didecene was identified as having a low ecological exposure potential. HTTD, however, was identified as having a moderate ecological exposure potential based on its overall persistence and quantities reported in recent surveys.

Key health and ecological effects (hazard)

• To help inform the health effects characterization in the assessment, international reports on these substances were considered, among other sources of information. This included assessments by the United States Environmental Protection Agency (US EPA) and the European Chemicals Agency (ECHA).
• The critical effects identified for characterizing the risk to human health for hydrogenated didecene and HTTD were effects on tissue in the nasal cavity and lungs through inhalation exposure (based on laboratory studies).
• No critical effects on human health have been identified for hydrogenated didecene and HTTD through the oral or dermal routes of exposure, based upon available information on these substances, and on similar chemicals, using read-across.
• According to information considered under the ERC Approach, hydrogenated didecene and HTTD were both identified as having low ecological hazard potential.

Consideration of subpopulations who may have greater susceptibility or greater exposure

• There are groups of individuals within the Canadian population who, due to greater susceptibility or greater exposure, may be more vulnerable to experiencing adverse health effects from exposure to substances.
• Certain subpopulations are routinely considered throughout the assessment process, such as infants, children, and people of reproductive age. For instance, age-specific exposures are routinely estimated, and developmental and reproductive toxicity studies are evaluated for potential adverse health effects. For the Decenes Group, these subpopulations were considered.

Risk assessment outcomes

• Assessments focus on information critical to determining whether substances are harmful to human health or the environment under CEPA. This is done by considering scientific information, including information, if available, on subpopulations who may have greater susceptibility or greater exposure, vulnerable environments and cumulative effects and by incorporating a weight of evidence approach and precaution.
• Based upon a comparison of levels to which people in Canada may be exposed to hydrogenated didecene and HTTD from their use in CLP spray products used for firearm maintenance and the levels associated with health effects, it was determined that these substances may pose a risk to human health.
• Based upon the outcome of the ERC Approach, these 2 substances are considered unlikely to be causing ecological harm at current levels of exposure.

Assessment conclusions

• The Government concluded that hydrogenated didecene and HTTD are harmful to human health at levels of exposure considered in the assessment. The Government also concluded that these substances are not entering the environment at levels that are harmful.

Preventive actions and risk reduction

• The Government intends to propose the addition of hydrogenated didecene and HTTD to Part 2 of Schedule 1 to CEPA. Adding a substance to Schedule 1 does not restrict its use, manufacture or import. Rather, it enables the Government to take enforceable risk management actions under CEPA.
• The proposed order adding hydrogenated didecene and HTTD to Part 2 of Schedule 1 to CEPA was published for a 60-day public comment period ending on January 21, 2026. Adding a substance to Schedule 1 does not restrict its use, manufacture or import. Rather, it enables the Government to take enforceable risk management actions.
  • Toxic substances that pose the highest risk (that is, meet certain criteria) are added to Part 1 of Schedule 1. These are prioritized for total, partial or conditional prohibition.
  • Other toxic substances are added to Part 2 of Schedule 1 and are prioritized for pollution prevention actions, which may include prohibition.
  • Regulations specifying criteria for the classification of substances that pose the highest risk or that are carcinogenic, mutagenic or toxic to reproduction will be developed. When criteria are available, some substances considered for addition to Part 2 of Schedule 1 may instead be considered for addition to Part 1 of Schedule 1.
• Publication of the risk management approach aims to inform stakeholders of proposed risk management actions and continue discussion about their development. The risk management approach indicates that the Government is considering the following actions to address human health concerns:
  • Regulations under CEPA that would establish concentration limits for hydrogenated didecene and HTTD in CLP spray and aerosol products available to consumers.
• Additional information is being sought by the Government to inform risk management decision-making. Details can be found in the risk management approach, including where to send information during the public comment period, ending 21 January, 2026.
• Risk management actions may evolve through consideration of assessments and risk management actions published for other substances. This is to ensure effective, coordinated, and consistent risk management decision-making.

Related resources

• Substances in the Decenes Group are found in products available to consumers. People in Canada should follow any safety warnings and directions related to the product and dispose of products responsibly.
• Visit Healthy home for information on chemical safety in and around the home, including on decenes.
• Assessments conducted under CEPA focus on risks of exposure of the general population. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). If a substance is harmful to the general population, it could also be of concern for individuals in situations where a higher volume of the substance is used or where the substance is used for a longer duration (for example, the workplace). The Government of Canada recognizes that it is the responsibility of the federal, provincial and territorial occupational health and safety organizations to coordinate legislation for the safe use of chemicals in the workplace. We are working to support this role by integrating the information, tools, and technical expertise of the CMP and Health Canada’s Workplace Hazardous Products Program.