Substituted Diphenylamines (SDPAs) - information sheet

Updated October 28, 2020:

The Final Screening Assessment for Substituted Diphenylamines (SDPAs) was published on December 9, 2017, under the Substance Groupings Initiative of the Chemicals Management Plan (CMP). The assessment is summarized in this information sheet and has not changed. The section in this information sheet 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 substances in the SDPA grouping.
  • Under 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 or to the environment. A substance may have hazardous properties; however, the risk to human health or to the environment may be low depending on the level of exposure.
  • As a result of the screening assessment, it was concluded that 14 SDPAs, including BNST, are not harmful to human health or to the environment, at levels of exposure considered in the assessment.

About these substances

  • Fourteen substituted diphenylamines (SDPAs) with similar chemical structures and physical-chemical properties were assessed as part of the Substance Groupings Initiative of the Chemicals Management Plan (CMP).
  • One of these substances is benzenamine, N-phenyl-, reaction products with styrene and 2,4,4-trimethylpentene, also known as BNST (CAS RN 68921-45-9).
  • BNST was previously assessed in 2009 as part of the Challenge Initiative. At that time, BNST was concluded as entering the environment at levels that may constitute a danger to the environment. However, based on new information obtained on SDPAs, BNST is no longer considered harmful to the environment.
  • The 14 SDPAs are industrial chemicals that do not occur naturally in the environment.
  • In Canada, SDPAs are mainly used as antioxidants in automotive and industrial lubricants, but also have some use in the manufacture of plastics or polyurethane foams and rubber products. SDPAs may be used as alternatives for each other.

Human and ecological exposures

  • Exposure of Canadians to SDPAs from the environment (for example, air, water, sediment or soil) is expected to be low.
  • Exposure of Canadians to SDPAs from the use of products available to consumers, such as foam cushioning and automotive lubricants, is expected to be low.
  • In Canada, SDPA manufacturing is expected to be the predominant sector leading to the release of these substances to the aquatic environment.
  • SDPAs also have the potential to be released to the environment during industrial activities (for example, blending lubricants, manufacturing plastic and rubber products) or during the use of lubricants.

Key health and ecological effects (hazard)

  • Some SDPA substances are associated with health effects to the liver and blood. These effects were considered the critical or important effects for characterizing risk to human health in this assessment.
  • The potential for adverse effects from SDPAs in the environment is low. However, these substances are persistent, and certain SDPAs that have a higher potential to be taken up by organisms have a higher relative ecological hazard potential.

Risk assessment outcomes

  • Results of the final screening assessment indicate that the environmental concentrations of SDPAs are below the level expected to cause harm to organisms.
  • Based upon a comparison of levels to which Canadians can be exposed, and the levels associated with health effects, it was determined that the risk to human health from the 14 SDPAs is low.
  • The Government of Canada published the Final Screening Assessment for Substituted Diphenylamines on December 9, 2017.

Screening assessment conclusions

  • As a result of the screening assessment, the Government concluded that the 14 SDPAs, including BNST, are not 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 to the environment.

Preventive actions and reducing risk

Additional considerations

  • Although the 14 SDPAs are not considered to be harmful to human health or the environment at current levels of exposure, some of the substances contain chemical structures that are available for uptake in organisms. Therefore, there may be a concern if exposures were to increase.
  • Follow-up activities for the 9 substances identified by CAS RNs 4175-37-5, 10081-67-1, 27177-41-9, 36878-20-3, 68411-46-1, 68442-68-2, 68608-79-7, 68921-45-9, and 184378-08-3 will involve including the substances in future information gathering initiatives, such as a mandatory survey under section 71 of CEPA 1999.
  • The Government will use the data gathered through these follow-up activities to prioritize further information gathering or risk assessment of these substances, if required.

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