Dinoseb - information sheet

Phenol, 2-(1-methylpropyl)-4,6-dinitro- (DNBP)
CAS Registry Number 88-85-7

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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 dinoseb.
  • 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 or 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 dinoseb is harmful to the environment, but not to human health at levels of exposure considered in the assessment. Although dinoseb has effects of concern for human health, it was determined that the risk posed by this substance to Canadians is low, given that human exposure is not expected.

About this substance

  • The screening assessment focused on the substance phenol, 2-(1-methylpropyl)-4,6-dinitro-, also referred to as dinoseb. It was assessed as part of the third phase of the Chemicals Management Plan (CMP).
  • According to information gathered, the largest use of dinoseb identified at the time of the assessment was in the industrial sector.
  • Dinoseb does not occur naturally in the environment. It was historically used in Canada as a pesticide, specifically as an herbicide. Registration of its pesticidal use was suspended in 1990 due to health concerns and no further uses were registered after 2000. The use of dinoseb as an herbicide has been discontinued since December 31, 2001.

Human and ecological exposures

  • Dinoseb is no longer used as a pesticide in Canada, nor is it used in products available to consumers. Data on Canadian drinking water reviewed at the time of the assessment did not detect dinoseb. Exposure of Canadians to dinoseb from air and food is also not expected.
  • The ecological assessment focused on the potential release of dinoseb to surface water from its use in the industrial sector. Dinoseb will break down slowly in water where it is expected to persist; however, it is not expected to bioaccumulate in aquatic organisms. Significant releases to air are not expected.

Key health and ecological effects (hazard)

  • Dinoseb has been reviewed internationally through the Organisation for Economic Cooperation and Development (OECD) Cooperative Chemicals Assessment Programme. The Screening Information Dataset Initial Assessment Report (SIAR) was used to inform both the human health and the ecological evaluations of dinoseb.
  • The European Commission classified dinoseb as toxic for reproduction (may damage the unborn child). Developmental effects were also considered to be critical effects considered in the risk assessment.
  • In the environment, dinoseb is a reactive chemical which may interfere with the production of energy in animals, plants, and fungi. Dinoseb is hazardous to various aquatic organisms, as well as to birds and mammals because it has effects on reproduction, survival and growth at very low concentrations.

Risk assessment outcomes

  • Exposure of Canadians to dinoseb is not expected; therefore, the risk to human health is considered to be low.
  • For the ecological assessment, exposures in surface water were modeled based on estimated industrial releases. Due to the severity of the effects of dinoseb on aquatic organisms, as well as birds and mammals, even very low levels of exposure may pose a risk to the environment.
  • Considering all information presented, it was determined that there is risk of harm to the environment from dinoseb.
  • The Government of Canada published the Final Screening Assessment for Dinoseb on February 6, 2021.

Screening assessment conclusions

  • As a result of the screening assessment, the Government concluded that dinoseb is not harmful to human health at levels of exposure considered in the assessment.
  • However, the Government concluded that dinoseb is entering or may enter the environment at concentrations that may be harmful to the environment.
  • It has been determined that dinoseb meets the persistence criteria, but not the bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.

Preventive actions and reducin g risk

  • The Government of Canada published the Risk Management Approach for Dinoseb on February 6, 2021. The public is invited to comment on this approach, during the 60-day public comment period ending on April 7, 2021.
  • The Government will consider adding phenol, 2-(1-methylpropyl)-4,6-dinitro- to Schedule 1 of CEPA 1999, also called the List of Toxic Substances.
  • The Government is considering the implementation of an environmental performance agreement, or a pollution prevention planning notice.
  • To further inform risk management decision-making, the Government is seeking information on:
    • the presence of dinoseb in the Canadian environment, especially surface water and wastewater/biosolids
    • changes in use patterns
  • Further information and updates on risk management actions for substances managed under the CMP can be found in the risk management actions table and the two year rolling risk management activities and consultations schedule.

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