Summary of public comments received on the screening assessment report for dinoseb

Comments on the draft Screening Assessment Report (dSAR) for dinoseb to be addressed as part of the Chemicals Management Plan (CMP) were provided by the Canadian Network for Human Health and the Environment (CNHHE); and a manufacturer of plastic foam products.

A summary of comments and responses from the Government of Canada are provided below, organized by topic:

1. New Information & Data

Summarized Comment Summarized Response
Literature searches yielded only a few relevant studies on dinoseb. This absence of evidence indicates a data gap that needs to be acknowledged and incorporated in hazard and risk assessments.   Screening assessments are based on the best available data and on conservative approaches when there is uncertainty.
The predicted environmental concentration (PEC) was derived using assumptions due to uncertainties in wastewater removal rates and the high method detection limit of the effluent monitoring data. To reduce the uncertainty, Environment and Climate Change Canada may work with our facility to analyze effluents for dinoseb using a method with a lower detection limit. The new data can be used to update the PEC in the final risk assessment. An analytical method with a lower detection limit (U.S. EPA 1992) was shared with the facility. New industrial effluent monitoring data that were provided by the submitter were considered, and the exposure analysis was updated in the assessment.

2. Methodology

Summarized Comment Summarized Response
Given the large and robust aquatic toxicity dataset available for dinoseb, application of a species sensitivity distribution (SSD) approach is suggested for determining the predicted no-effect concentration (PNEC). When sufficient data are available the SSD approach is preferred. Although there was a large set of acute toxicity data for dinoseb, chronic toxicity data were limited. Given the specific mode of action for dinoseb, it would not be appropriate to assess dinoseb based on an acute SSD. To conduct a chronic SSD, additional chronic toxicity data for fish and invertebrates is required.
Weight of evidence approaches were used to provide different assessments of hazards and risks. Transparency about the expert-informed judgments involved is crucial. In this case, omitting relevant occupational health hazards and related literature is done without any accounting or transparency. When conducting risk assessments, the Government of Canada applies a weight of evidence approach and precaution. This approach considers key information and uncertainties across multiple lines of evidence.

The focus of the assessment is on exposures to the general population. However, when available and relevant, hazard information from occupational settings is considered in a screening assessment.

3. Sources and Releases

Summarized Comment Summarized Response
It is not indicated where the water samples were taken in relation to possible sources (such as styrene production facilities), which makes it difficult to know the relevance of the monitoring data. The production facilities and their location should be named in the assessment. Substance screening assessments under the Canadian Environmental Protection Act, 1999 (CEPA 1999) are based on available data and information that represents a range of potential exposure scenarios in Canada. Effluent monitoring data from a styrene production facility were used in the exposure analysis. However, as CMP assessments are not intended to be site-specific assessments, the locations and names of facilities considered are not relevant information.
The statement in the dSAR that significant releases to air are not expected is questionable, given that releases of dinoseb to air at U.S. chemical manufacturing facilities have been reported. The dSAR notes uncertainty around the potential for releases to air from industrial facilities. Since American facilities report low releases, releases are not expected to be significant in Canada either.

4. Risk Characterization

Summarized Comment Summarized Response
The Government says potential risk to human health from dinoseb is low, but that there might be concern “if exposures were to increase”. This is inconsistent with current toxicology and other scientific information, which identifies dinoseb as a possible endocrine disruptor. Exposure of the general population in Canada to dinoseb is not expected. The screening assessment presents reproductive and developmental effects in laboratory studies, which may be based on an endocrine-related mode of action. For more information, consult the Risk Assessment Series Fact Sheet: Consideration of endocrine-related effects in risk assessment (available online).
The Government ignores the occupational health consequences of dinoseb used in styrene monomer production, which is a concern for human health. Neither the Risk Management Scope (RMS) nor the dSAR mentions information about work-related exposure levels or how the chemical affects workers’ health. Screening assessments conducted under CEPA are based on the best available data. Under the CMP, the focus is on risks of exposure to the general population, rather than risks of exposures in the workplace. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS).

For information concerning workplace health and safety, Canadians should consult with their employer, an occupational health and safety (OHS) representative or the OHS regulator in your jurisdiction for information on what steps to take in the workplace.

The Government of Canada is currently exploring ways to enhance the protection of workers from exposure to chemicals by integrating and leveraging the information, tools, and/or technical expertise of the Chemicals Management Plan and Health Canada’s Workplace Hazardous Products Program (An Integrated Strategy for the Protection of Canadian Workers from Exposure to Chemicals. Publication date: 2019-07-11).

5. Conclusion

Summarized Comment Summarized Response
Dinoseb is a toxic chemical that should be on the Government’s List of Toxic Substances since it poses serious environmental and human health hazards. As a result of the screening assessment, dinoseb was concluded to be harmful to the environment, but not to human health at current levels of exposure. Dinoseb is recommended for addition to Schedule 1 of the CEPA 1999, also called the Toxic Substances List.

6. Risk Management

Summarized Comment Summarized Response
Dinoseb is toxic to humans and the environment. As a result, the Government of Canada should consider a more comprehensive approach and broader issues related to dinoseb, specifically the production and use of styrene and chemical additives in general. The Government of Canada should also consider potential risks from substances that are similar to dinoseb, such as alkylphenols and nitro compounds. The screening assessment concludes that current levels of exposure do not pose a risk to the general population. As indicated in therisk management approach, other activities to track commercial use patterns associated with styrene monomer production, or more broadly with additives in the chemical sector may be considered in the future.
The use, presence and releases of dinoseb should be tracked, potentially through the National Pollutant Release Inventory (NPRI). Substances that meet Section 64 of CEPA 1999 are given high priority in NPRI consultations. Any party (person, government or organization) in Canada may submit a proposal to ECCC for changes to the NPRI program. Other options for collecting data on releases of dinoseb may also be considered as part of the risk management approach.
Table 4-1 of the SAR is misleading because it seems to indicate that dinoseb is not present in cosmetics. However, dinoseb is not on the list of banned or restricted ingredients. Dinoseb should be added to the Canadian Cosmetic Ingredient Hotlist, and efforts should be made to find out if it is used in any products produced or imported into the country. All cosmetics sold in Canada must be notified to Health Canada as stated in the Cosmetic Regulations. Dinoseb was not notified as an ingredient in cosmetic products in Canada according to the Cosmetic Notification System. Proposed risk management actions focus on reducing dinoseb releases to water from industrial activities and related processes.
Risk management actions should be more protective than what is currently proposed and should be aligned with actions in the European Union. Proposed actions focus on reducing dinoseb releases to water from industrial activities and related processes. These actions include regulatory or non-regulatory controls to minimize releases of dinoseb to the environment. Existing risk management actions in other jurisdictions may be considered as part of the decision-making.

7. Alternatives & Informed Substitution

Summarized Comment Summarized Response
Dinoseb is a good candidate for consideration of informed substitution in order to prevent regrettable substitution. The stakeholder provided information on potential substitutes for dinoseb and technical papers on the styrene industry’s testing of alternatives. Informed substitution efforts need to also consider the polymerization inhibitors and not just the use as a polymerization retarder. When developing risk management approaches, the Government of Canada considers costs and availability of alternatives when determining the appropriate actions to address risk. Different strategies, tools, and data sources are used to obtain information on existing chemical alternatives to inform the risk management actions that are selected to mitigate the risks; however, a formal, systematic evaluation of the hazard of alternatives is not carried out by the departments in the risk management phase. Information on potential alternatives to dinoseb has been identified as a risk management information gap in the Risk Management Scope for dinoseb. The information provided on potential substitutions for dinoseb will be reviewed and where applicable, considered in risk management decision-making.

For more information on informed substitution under the Chemicals Management Plan, please refer to the Combined government discussion paper and science committee report on informed substitution, where applicable. When developing risk management approaches, the Government of Canada considers costs and availability of alternatives and alternative technologies such as the use of styrene inhibitors and retarders in the process.
The Government of Canada should also consider that when dinoseb is incinerated it generates nitrogen oxides that are known air pollutants. The potential for release of nitrogen oxides when dinoseb is incinerated is not expected to produce significant quantities of nitrogen oxides compared to other ambient air sources. Releases over a certain threshold of nitrogen oxides are reported through various programs within the Government of Canada, including the Air Emissions Inventory. Various codes of practice and guidelines have been put in place by the Canadian Council of Ministers of the Environment.

The potential for release of nitrogen oxides and other substances from incineration of dinoseb may be considered during risk management decision-making.
Informed substitution and other risk management actions often do not consider the cost of the problem in the entire lifecycle context. California’s alternatives assessment process may provide some useful information on costs throughout the lifecycle. When developing risk management approaches, the CMP considers substitutes and alternatives when adequate and relevant information is available on the economic, social and environmental implications for Canada. The Government of Canada is currently exploring ways to advance responsible replacement of chemicals of concern, including ways to apply informed substitution to support chemicals management (Combined government discussion paper and science committee report on informed substitution. Publication date: 2018-08-28).

8. Consultation and Stakeholder Engagement

Summarized Comment Summarized Response
Additional work and analysis is being offered to fill data gaps and mitigate the risk of releases of dinoseb to the environment. Noted.

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