Canada Gazette, Part I, Volume 156, Number 40: Order Adding a Toxic Substance to Schedule 1 to the Canadian Environmental Protection Act, 1999 [Dinoseb]

October 1, 2022

Statutory authority
Canadian Environmental Protection Act, 1999

Sponsoring departments
Department of the Environment
Department of Health


(This statement is not part of the Order.)


Government officials conducted a risk assessment as part of its Chemicals Management Plan on phenol, 2-(1-methylpropyl)-4,6-dinitro- (CAS RNfootnote 1 88-85-7, also known as dinoseb). Based on the assessment, dinoseb meets the ecological criterion set out in paragraph 64(a) of the Canadian Environmental Protection Act, 1999 (CEPA or the Act). In accordance with subsection 90(1) of CEPA, the Minister of the Environment and the Minister of Health (the ministers) are recommending that the Governor in Council make an order adding dinoseb to Schedule 1 to the Act (the List of Toxic Substances).


The Chemicals Management Plan (CMP) is a federal program that assesses and manages chemical substances and living organisms that may be harmful to the environment or human health. The ministers assessed dinoseb in accordance with section 68 of CEPA as part of the CMP.

Description, uses and sources of release

Dinoseb does not occur naturally in the environment and is not used in products available to consumers. Although dinoseb was previously used as an herbicide in Canada, the registration of all non-essential pesticidal uses of dinoseb was suspended in 1990, and the use of dinoseb as an herbicide has been discontinued since December 31, 2001. Dinoseb is currently used in Canada in the industrial process of producing styrene monomer, an industrial chemical and raw material used to make various plastics and synthetic rubbers such as polystyrene. The primary source of dinoseb in the environment is through the release of wastewater generated through the production of styrene monomer. An additional source of dinoseb in the environment occurs from dinoseb salts, in particular dinoseb acetate, which break down to produce dinoseb itself after being released into the environment. Dinoseb acetate can enter the environment through releases of wastewater from small industrial facilities.

Notifications of intended exports of dinoseb into Canada obtained under the export notification provisions of the Rotterdam Convention and from discussions with industry indicate that between 100 000 kilograms (kg) and 1 000 000 kg of dinoseb were imported in 2015. Canada Border Services Agency data also reveal that 18 different companies imported quantities of dinoseb acetate of typically less than 100 kg per company per year between 2011 and 2020; however, it is not known how these smaller quantities are being used.

Current risk management activities

National level

The use of dinoseb as an herbicide has been discontinued in Canada since 2001. Controls on the export of dinoseb have also been placed under the Export of Substances on the Export Control List Regulations.footnote 2 The import of dinoseb for use as a pesticide has been prohibited by all of the Parties to the Rotterdam Convention, of which Canada is a party. Dinoseb is subject to Canadian water quality guidelines for concentrations with respect to the protection of agricultural uses and aquatic life. Lastly, dinoseb is regulated via controls under the Transportation of Dangerous Goods Act, 1992 and its regulations and the Cross-border Movement of Hazardous Waste and Hazardous Recyclable Material Regulations to regulate disposal and recycling of dinoseb.

International level

Internationally, dinoseb is a restricted chemical listed in Annex III of the Rotterdam Convention, making it subject to the prior informed consent (PIC) procedure. Dinoseb was assessed by the Organisation for Economic Co-operation and Development (OECD) in 2007 and it was determined that the substance is a candidate for further work indicating a hazard to the environment.

In the European Union (EU), dinoseb, its acetate and salts are banned in pesticides in the active substance regulation. Dinoseb is subject to the Classification, Labelling and Packaging Regulation in which all chemicals that are exported have to comply with rules for packaging and labelling. Dinoseb is prohibited in cosmetic products in the EU.

In the United States, dinoseb is on the Environmental Protection Agency (EPA) list of banned or severely restricted pesticides and is also a registered pesticide under the Federal Insecticide, Fungicide and Rodenticide Act. Dinoseb is listed in the Toxic Release Inventory, and the Safe Drinking Water Act specifies the maximum contaminant level for dinoseb.

Summary of the screening assessment

In February 2021, the ministers published a screening assessment on dinoseb on the (Chemical substances) website. The screening assessment was conducted to determine whether the substance meets one or more of the criteria for a toxic substance as set out in section 64 of CEPA.

Under section 64 of CEPA, a substance is considered toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that

The Department of the Environment and the Department of Health (the departments) generated and collected information from modelling, literature reviews and database searches to inform the screening assessment conclusion. The ecological portion of this assessment has undergone external peer review and consultation with officials at the Pest Management Regulatory Agency, the European Chemicals Agency and the U.S. EPA.

The screening assessment concluded that dinoseb meets the ecological criterion for a toxic substance as set out in paragraph 64(a) of CEPA and thus constitutes a risk to the environment in Canada. Below are summaries of the ecological and human health assessments.

Summary of the ecological assessment

The ecological assessment focused on the potential release of dinoseb to surface water and impacts on aquatic species from its use in the chemical sector. Dinoseb will break down slowly in water where it is expected to persist and have long-range transport potential; however, it is not expected to bioaccumulate in aquatic organisms. Significant releases to air or soil are not expected based on known uses of dinoseb in Canada at this time.

The acute and chronic toxicity of dinoseb to aquatic organisms has been well established in dozens of experimental studies dating back to the 1970s. In birds and mammals, adverse effects from exposure include reproductive and developmental effects.

A risk quotient analysis was conducted to assess whether various exposure scenarios for releases of dinoseb may pose an ecological risk. The risk quotient value, calculated as the ratio between the predicted environmental concentrations (PECs) and the predicted no-effect concentration (PNEC), provides insights into whether there is a potential for ecological harm. The PEC was found to be greater than the PNEC in three of the seven exposure scenarios considered in this analysis; therefore, there is the potential for exposure concentrations resulting from industrial activities to exceed chronic no-effect thresholds in the receiving environment, even when dinoseb is used in very small quantities.

The screening assessment concluded that dinoseb meets the ecological criterion for a toxic substance set out in paragraph 64(a) of CEPA, but was not found to meet the criterion set out in paragraph 64(b).

The assessment also determined that dinoseb meets the persistence criteria, but not the bioaccumulation criteria, as set out in the Persistence and Bioaccumulation Regulations.

Summary of the human health assessment

The health effects characterization in the screening assessment was informed by the OECD Screening Information Dataset Initial Assessment Report for dinoseb (PDF), in which the main endpoints of concern are reproductive and developmental toxicity, based on several studies on experimental animals. A literature search for content up to September 2016 yielded no additional studies that altered the screening assessment. The European Commission classifies dinoseb as toxic for reproduction, with a potential to harm the unborn child and is suspected of damaging fertility.

Although dinoseb has effects of concern for human health, including reproductive and developmental effects, the risk posed by this substance to Canadians is low given that human exposure is not expected. Dinoseb is not expected in air, drinking water or food and is not used in products. Any human exposure resulting from releases of industrial wastewater would be several orders of magnitude lower than the levels associated with adverse health effects. However, there may be a concern for human health if exposure was to increase.

The screening assessment concluded that dinoseb does not meet the human health criterion for a toxic substance as set out in paragraph 64(c) of CEPA.


The objective of the proposed Order Adding a Toxic Substance to Schedule 1 to the Canadian Environmental Protection Act, 1999 (the proposed Order) is to add dinoseb to the List of toxic substances in Schedule 1 to CEPA. This would enable the ministers to propose risk management measures for a toxic substance under CEPA to manage potential environmental risks associated with the substance.


The proposed Order would add phenol, 2-(1- methylpropyl)-4,6-dinitro- to Schedule 1 to CEPA (the List of Toxic Substances).

Regulatory development


On June 2, 2018, the ministers published a notice with a summary of the draft screening assessment for dinoseb (which included a link to the complete draft assessment) in the Canada Gazette, Part I, for a 60-day public comment period. The notice also informed of the publication of the risk management scope document for dinoseb to initiate discussions with stakeholders on the development of risk management actions, which would be proposed following its addition to Schedule 1 to CEPA. Comments on the screening assessment and risk management scope were received from one industry stakeholder and one non-governmental organization. A table summarizing the complete set of comments received and the response to these comments is available on the (Chemical substances) website. In addition, an Indigenous group provided a public comment that was considered in the development of the risk management approach.

Stakeholders provided additional information and studies on the releases and effects of dinoseb to address certain data gaps. Industry stakeholders questioned why the Government did not consider using a species sensitivity distribution approach in the methodology of the assessment. Departmental officials responded that chronic toxicity data were not available for enough species to support the use of a species sensitivity distribution approach. One non-governmental organization questioned the assessment’s assertion that dinoseb is not present in cosmetics, given that it is not on the list of banned or restricted ingredients. Departmental officials clarified that Health Canada must be notified of the ingredients in all cosmetics sold in Canada and that Health Canada has not been notified of any cosmetics in Canada with dinoseb as an ingredient. A non-governmental organization also submitted comments that suggested the Government incorporate occupational exposure into the assessment. Officials noted that screening assessments conducted under CEPA focus on the risk of exposure to the general population rather than risks of exposure in the workplace. All stakeholders showed support to the mitigation of risks from dinoseb releases to the environment. A non-governmental organization recommended using a more comprehensive approach to tackle broader issues related to dinoseb, including the use of similar substances, tracking dinoseb through the National Pollutant Release Inventory, listing it on the Cosmetic Ingredient Hotlist and aligning risk management actions with those of the European Union. The Indigenous group and the non-governmental organization both provided information and recommendations on potential substitutes for dinoseb. These comments were considered in the development of the final screening assessment report published on February 6, 2021, but did not change the conclusion that dinoseb met the criterion for a toxic substance as set out under paragraph 64(a) of CEPA.

On February 6, 2021, the ministers published a risk management approach document on the (Chemical substances) website to continue discussions with stakeholders on the proposed risk management options for this substance. In particular, the Government of Canada is proposing to implement an environmental performance agreement (EPA), which is proposed to include provisions requiring adherence to a code of practice or best management practices.

Departmental officials will address comments on the management of environmental risks posed by the substance during the development of the aforementioned risk management measures or regulatory initiatives, which would be subject to their own consultation processes. Comments from public, partner, Indigenous and stakeholder consultations will continue to be considered during the development of any risk management instrument associated with the substance.

The departments inform the provincial and territorial governments about all publications through the CEPA National Advisory Committee (CEPA NAC)footnote 3 via a letter and provide them with an opportunity to comment. No comments were received from the Committee on this publication.

Modern treaty obligations and Indigenous engagement and consultation

An assessment of modern treaty implications conducted in accordance with the Cabinet Directive on the Federal Approach to Modern Treaty Implementation concluded that orders adding substances to Schedule 1 to CEPA do not introduce any new regulatory requirements and therefore do not result in any impact on modern treaty rights or obligations. Consequently, specific engagement or consultations with Indigenous Peoples were not undertaken. However, the prepublication comment period is an opportunity for Indigenous Peoples to provide feedback on the proposed Order, which is open to all Canadians. For any proposed risk management measures for dinoseb, the departments would assess any associated impact on modern treaty rights or obligations and requirements for Indigenous engagement and consultations during the development of such measures.

Instrument choice

When a substance meets one or more of the criteria for a toxic substance as set out in section 64 of CEPA, the ministers may propose one of the following measures:

The implementation of virtual elimination is applicable only if a substance is assessed under section 74 of CEPA. The implementation of virtual elimination does not apply to dinoseb, as it was assessed under section 68 of CEPA.

Based on the available evidence, the ministers determined that it is not appropriate to manage the potential ecological risks associated with the substance by taking no further action or adding the substance to the Priority Substances List (option A or option B); therefore, the ministers recommend that dinoseb be added to Schedule 1 to CEPA (option C). An order is the only available instrument to implement this recommendation.

Regulatory analysis

Benefits and costs

The addition of dinoseb to Schedule 1 to CEPA would not, on its own, impose any regulatory requirements on businesses and therefore would not result in any incremental compliance costs for stakeholders or enforcement costs for the Government of Canada. The proposed Order would grant the ministers the authority to develop risk management instruments under CEPA for these substances. The Government of Canada would consult stakeholders on any future risk management instruments before implementation and would consider their potential impacts.footnote 6

Small business lens

The small business lens analysis concluded that the proposed Order would not impact Canadian small businesses, as it would not impose any administrative or compliance costs on businesses.

One-for-one rule

The one-for-one rule does not apply, as the proposed Order would not result in a change in the administrative burden imposed on businesses.

Regulatory cooperation and alignment

Canada cooperates with other international organizations and regulatory agencies for the management of chemicals (e.g. the United States Environmental Protection Agency, the European Chemicals Agency and the Organisation for Economic Co-operation and Development). Dinoseb and its salts and esters are listed in Annex III of the Rotterdam Convention for pesticide uses, making them subject to the prior informed consent (PIC) procedure. While the proposed Order alone would not relate to any international agreements or obligations, it would enable the ministers to propose risk management measures that may align with actions undertaken by other jurisdictions.

Strategic environmental assessment

In accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals, a strategic environmental assessment was completed for the CMP, inclusive of orders adding substances to Schedule 1 to CEPA. The assessment concluded that the CMP is expected to have a positive effect on the environment and human health.

Gender-based analysis plus

No gender-based analysis plus (GBA+) impacts have been identified for this proposal.

Implementation, compliance and enforcement, and service standards

As no specific risk management measures are recommended as part of the proposed Order, developing an implementation plan and a compliance and enforcement strategy, as well as establishing service standards, are not necessary at this time.


Thomas Kruidenier
Acting Executive Director
Program Development and Engagement Division Environment and Climate Change Canada
Gatineau, Quebec
K1A 0H3
Substances Management Information Line:
1‑800‑567‑1999 (toll-free in Canada)
819‑938‑3232 (outside of Canada)

Andrew Beck
Risk Management Bureau
Health Canada
Ottawa, Ontario
K1A 0K9
Telephone: 613‑266‑3591


Notice is given, under subsection 332(1)footnote a of the Canadian Environmental Protection Act, 1999 footnote b, that the Governor in Council, on the recommendation of the Minister of the Environment and the Minister of Health, under subsection 90(1) of that Act, proposes to make the annexed Order Adding a Toxic Substance to Schedule 1 to the Canadian Environmental Protection Act, 1999.

Any person may, within 60 days after the date of publication of this notice, file with the Minister of the Environment comments with respect to the proposed Order or a notice of objection requesting that a board of review be established under section 333 of that Act and stating the reasons for the objection. All comments and notices must cite the Canada Gazette, Part I, and the date of publication of this notice, and be sent to the Executive Director, Program Development and Engagement Division, Department of the Environment, Gatineau, Quebec K1A 0H3 (email:

A person who provides information to the Minister of the Environment may submit with the information a request for confidentiality under section 313 of that Act.

Ottawa, September 22, 2022

Wendy Nixon
Assistant Clerk of the Privy Council

Order Adding a Toxic Substance to Schedule 1 to the Canadian Environmental Protection Act, 1999


1 Schedule 1 to the Canadian Environmental Protection Act, 1999 footnote b is amended by adding the following in numerical order:

162 Phenol, 2-(1-methylpropyl)-4,6-dinitro-, which has the molecular formula C10H12N2O5

Coming into Force

2 This Order comes into force on the day on which it is registered.

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