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, of dinoseb to address the potential for harm to Canadians and to the environment.
  • 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 this screening assessment, dinoseb is proposed to be harmful to the environment, but not to human health at current levels of exposure. 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

  • This screening assessment focuses 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).
  • Historically, dinoseb was used in Canada as a pesticide, specifically 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 prohibited since December 31, 2001.
  • The only current use of dinoseb in Canada is in the chemical sector. It is known to be imported for this activity. The substance does not occur naturally in the environment.

Exposure of Canadians and the environment

  • Dinoseb is no longer used as a pesticide in Canada, nor is it used in products available to consumers. Recent drinking water monitoring data from across Canada show no detection of dinoseb. Exposure of Canadians to dinoseb, including from the environment, is not expected.
  • The ecological assessment focused on the potential release of dinoseb to surface water from its use in the chemical 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)

  • To identify effects of concern for human health, international and national reports of data on dinoseb were reviewed. Dinoseb was assessed through the Organisation for Economic Co-operation and Development's (OECD) Cooperative Chemicals Programme. The important or "critical" effects of concern identified for human health are reproductive and developmental effects.
  • In the environment, dinoseb is a reactive chemical and has the effect of interfering with the production of energy in animals, plants, and fungi. Dinoseb is hazardous to various forms of 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

  • Among other sources of information, the OECD Screening and Information Data Set Initial Assessment Report (SIAR) was used to inform both the human health and the ecological evaluations of dinoseb. These OECD assessments undergo rigorous review (including peer-review) and endorsement by international governmental authorities. Health Canada and Environment and Climate Change Canada are active participants in these processes and consider these assessments reliable.
  • 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 releases from its use in the chemical sector. Due to the severity of the effects of dinoseb on aquatic organisms, as well as birds and mammals, more importance was given to hazard than to exposure in the assessment of risk posed by dinoseb to the environment.
  • A comparison of potential exposures with effect levels showed that there is possible risk of harm to aquatic organisms from dinoseb. Considering all of the information presented, it was determined that dinoseb poses a risk of harm to organisms, but not to the broader integrity of the environment.
  • Dinoseb is proposed to meet the persistence criteria but not the bioaccumulation criteria as set out in the Persistence and Bioaccumulation Regulations of CEPA 1999.
  • The Government of Canada published the Draft Screening Assessment for Dinoseb on June 2, 2018. This publication has a 60-day public comment period ending on August 1, 2018.

Proposed screening assessment conclusions

  • As a result of this screening, the Government is proposing that dinoseb is not harmful to human health at current levels of exposure.
  • However, the Government is proposing that dinoseb is entering or may enter the environment at concentrations that may be harmful to the environment.

Preventive actions and reducing risk

  • The Government of Canada published the Risk Management Scope for Dinoseb on June 2, 2018. This publication has a 60-day public comment period ending on August 1, 2018.
  • The Government intends to add phenol, 2-(1-methylpropyl)-4,6-dinitro- to Schedule 1 of CEPA 1999, also called the List of Toxic Substances.
  • If the proposed conclusion is confirmed in the final screening assessment, the Government is proposing to consider the implementation of controls to prevent or minimize the release of dinoseb to the environment from the industrial use of this substance.
  • Also, the Government is seeking further information to inform risk management decision-making. Details can be found in the Risk Management Scope for Dinoseb, including where to send information during the public comment period ending August 1, 2018.
  • Further information and updates on risk management actions can be found in the CMP risk management actions table and the two year rolling risk management activities and consultations schedule.

Important to know

  • Canadians who may be exposed to dinoseb in the workplace should consult with their employer and an occupational health and safety (OHS) representative about safe handling practices, applicable laws, and requirements under OHS legislation and the Workplace Hazardous Materials Information System (WHMIS).
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