Summary of public comments received on the draft screening assessment for dicyclopentadiene (DCPD)

Comments on the draft Screening Assessment for Dicyclopentadiene assessed under the Chemicals Management Plan (CMP), were submitted by the Canadian Network for Human Health and the Environment (CNHHE) and the Canadian Fuels Association.

Summarized public comments and responses are provided below, organized by topic.

Methodology and conclusions

Summarized comment Summarized response

A precautionary approach was not used in the assessment. “Weight of evidence” as a method can have multiple meanings. Suggestions for how to use the weight of evidence approach to assess chemical hazards are provided in letters (links) submitted.

Not having data does not mean there is no harm. More precaution should be taken when data are absent.

A weight-of-evidence approach, as described in the Application of weight of evidence and precaution in risk assessment fact sheet, is used in screening assessments conducted under the CMP. This approach weighs various sources of information to identify critical values used in the assessment and considers the relative strengths, consistency, coherency, relevance, and uncertainties of various data. It evaluates multiple lines of evidence, including the hazardous properties of the substance, and the nature and extent of the exposure of Canadians or organisms to the substance, to determine if a substance may pose a risk to human health or to the environment.

Conclusions from the screening assessments also reflect a weight of evidence and precautionary approach, as described in the fact sheet link above. For example, the most susceptible populations (such as children) or receptors (such as early life stages of fish) as well as critical effects (such as mortality, reproductive impairment, endocrine effects, and carcinogenicity) are identified and evaluated. This is done using literature and database searches, information submitted by stakeholders through voluntary or mandatory surveys, and previous reviews or assessments of substances conducted by national or international agencies. Information is also generated by government researchers or stakeholders carrying out studies, testing, or monitoring of substances.

Where there are uncertainties or data needs, key sources of uncertainty are shown in the evaluation of risk. Where computer modelling is used to predict exposure or effects, conservative/protective approaches are used.

Where applicable, precaution is applied at various stages of an assessment to avoid the potential underestimation of risk due to a lack of information. However, if multiple assumptions are made throughout the assessment, there also needs to be consideration of whether the end result would be a conclusion that is unrealistic. In this case, further refinement of assumptions may be needed. If conservative assumptions have been made but there is no indication of potential risk to either human health or the environment, then further refinement is not needed.

Additionally, care is taken to ensure uncertainties are captured and communicated in the screening assessment.

There is no transparency when the assessment cites “unreferenced communications” from other Government staff. For example, how do we know that the adhesive does not come in direct contact with packaged food?

Unreferenced communications with government staff involves consulting experts and internal databases in various program areas within Health Canada or Environment and Climate Change Canada, for example, to gain information on levels of exposure of Canadians to substances from specific sources.

The data used in the assessment on emission rates from gasoline service stations is old. Urban Toronto in 2020 is different than it was in the past due to more vehicles and service stations.

Screening assessments conducted under the Canadian Environmental Protection Act, 1999 (CEPA) are based on the best available data. Information gathering encompasses a wide variety of published and unpublished sources. An updated literature search was conducted during the development of the final screening assessment. No significant new exposure or health effects data that would impact the conclusion of the assessment were identified.

The assessment does not properly account for available information on ecological or human effects and relies on old data. The assessment should be changed to conclude that DCPD is “toxic” under CEPA. The conclusion decision should be delayed until information from the European Chemicals Agency (ECHA) becomes available. The final assessment should reflect the Globally Harmonized System (GHS) classifications recognized by ECHA and others as well as test information submitted to ECHA.

Screening assessments focus on information critical to determining whether substances meet the criteria as set out in section 64 of CEPA by examining scientific information and incorporating a weight of evidence approach and precaution.

The determination of risk considers both the hazard of and exposure to a substance. Data on the hazard of DCPD to aquatic organisms and their expected level of exposure to DCPD indicate a low level of risk, according to information considered in the Ecological Risk Classification of organic substances (ERC) Approach. Ecological data on persistence, bioaccumulation and fish toxicity available from ECHA are in agreement with the values considered in the ERC Approach. Therefore, no changes have been made to the ecological assessment in the screening assessment.

For the human health assessment, health effects data available from ECHA as well as classifications were reviewed and considered in the screening assessment.

The Ministers make decisions about substances based on available information in order to safeguard human health and the environment. New information can be submitted through several mechanisms defined under specific sections of CEPA and other legislation. When appropriate, the Ministers may conduct additional evaluations of substances assessed under the CMP.

We support the draft screening assessment, as published, and find it balanced and representative of relevant hazard and exposure information for this substance.


Every chemical assessment should include information about informed substitution. This has not been done in this assessment despite the Government’s interest in the topic.

It is beyond the scope of this assessment to identify alternative chemicals or processes. However, when a substance(s) is found toxic and risk management is developed, the Government of Canada considers identified substitutes and alternatives whenever possible and when adequate and relevant information is available.

As the Government of Canada moves towards modernizing its chemical management program in the future, it will explore ways in which to support Industry and Canadians to make informed choices. Mechanisms such as the Identification of Risk Assessment Priorities process are applied by the Government of Canada to monitor new information on substances. The Government of Canada is also exploring ways to advance responsible replacement of chemicals of concern, as expressed in the Combined government discussion paper and science committee report on informed substitution.

Information and data

Summarized comment Summarized response

Many references used in the assessment are from industry and not “independent” sources. Some references are “hidden” within other sources (for example, ECHA or EPA documents).

All studies are reviewed to ensure that they are of good quality and valid or from reviews which do the same. They are then considered in the development of the screening assessment.

While the Organisation for Economic Co-operation and Development (OECD) and the United States Environmental Protection Agency (US EPA) assessments or reviews were used to inform the health effects characterization in this screening assessment, the original studies used in those international assessments were sometimes cited to increase transparency. For example, the 13-week inhalation study in B6C3F1 mice was cited as “(Exxon 1980; Dodd et al. 1982 in US EPA 2014 and also published as Kransler 2014)”. Reports produced under the OECD are reviewed by relevant regulatory authorities.

GHS classifications and the ECHA rationale of including DCPD in the Community Rolling Action Plan (CoRAP) indicate the possibility of DCPD being a reproductive/developmental toxin and describe the limitations of the available data for reproductive/developmental toxicity. This is not reflected in the CMP assessment.

The human health effects characterization in the screening assessment considered available data including assessing data quality, and describes the available reproductive and developmental toxicity data.

The critical effect levels used in the risk characterization for comparisons to potential exposures were selected to be protective of possible reproductive and developmental effects.

The stakeholder submitted hazard information from PubChem and other sources, including GHS and other classifications, with links to resources.

The information submitted was considered. Toxicity (hazard) data is considered in comparison to potential exposures in the assessment of risk.

Occupational exposure and vulnerable populations

Summarized comment Summarized response

The assessment does not account for occupational hazards and workers that may be exposed to DCPD. The assessment did not account for workers that still pump gas in Canada. The CMP program has acknowledged that this is an important public health aspect for future work.

Although DCPD is reportable under the National Pollution Release Inventory (NPRI), the disposal amounts are more than the reported on-site releases. Workers may be exposed.

The 2002 OECD paper accounts for workers wearing Personal Protective Equipment (PPE); however, there are flaws with the assumption that PPE will protect all workers.

Screening assessments conducted under CEPA are based on the best available data. Under the CMP, they focus on risks of exposure to the general population. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS).

The Government of Canada is currently working with the provinces and territories to explore ways to enhance the protection of workers from exposure to chemicals by integrating and leveraging the information, tools, and/or technical expertise of the CMP and Health Canada’s Workplace Hazardous Products Program.

On and off-site disposals are already regulated and are therefore not considered in this assessment. On-site releases which are most likely to lead to general population exposures are accounted for in this assessment.

ECHA lists a variety of uses for “professional workers” that are not in the CMP assessment. This raises concerns of whether workers or the public are being protected by the assumptions in the CMP assessment.

ECHA also reports that DCPD is included in the CoRAP in part on the grounds of worker exposure. This is not reflected in the CMP assessment.

This assessment only considers uses with potential exposure to the general population of Canada. The uses reported in ECHA were taken into consideration in this assessment; however, exposure to DCPD through automotive engine oil enhancer, refuelling, and living within the vicinity of gasoline service stations were considered to be the predominant sources of potential exposure of the general population in Canada to DCPD.

The Government should investigate the mixture effects of DCPD and other petroleum-based chemicals for workers, communities (especially Indigenous ones) and the general environment.

There is no acknowledgement of the situation facing the Aamjiwnaang First Nation. Their ancestral land near Sarnia is surrounded by petroleum refineries and chemical plants, and it’s not clear whether they are exposed to DCPD and what the effects of mixtures of chemicals might be for their community, others, and workers in the facilities.

The potential toxicity of mixtures through cumulative, synergistic, and antagonistic effects is not precluded from a screening assessment. However, in order to be considered, sufficient information to undertake such analyses would be needed. The information typically available for assessing effects is representative only of a substance’s inherent ability to elicit adverse effects.

When information is available that suggests a specific sub-population may be at a greater risk than the general population (for example, due to increased biological susceptibility or increased exposure), conservative exposure scenarios that account for both the general population and the sub-population are considered in the risk assessment.  

In 2018, the Government consulted on a draft definition of vulnerable populations and posted a “What we heard” report. Since this time, the departments continue to build on policy work and enhance consideration on vulnerable populations across the CMP.  

Concentrations of DCPD in environmental media were estimated based on the highest industrial release quantities of DCPD reported under the NPRI from 2013 to 2017. The majority of the DCPD releases were reported from petrochemical manufacturing, petroleum refineries, resin and synthetic rubber manufacturing, and other basic organic chemical manufacturing sectors. This includes DCPD releases from a chemical plant located in Sarnia.

Individuals living in the vicinity of a gasoline service station was determined to be the sentinel scenario in this assessment for daily inhalation exposure to DCPD. Estimates were derived for individuals living as close as 100 metres to a gasoline service station as was identified by photomap analysis. This scenario is protective of individuals living near refineries and chemical plants that use DCPD.

Consultation and stakeholder engagement

Summarized comment Summarized response

The Government of Canada should have discussions with the Canadian Labour Congress and the CMP Stakeholder Advisory Council (SAC) about how occupational hazards and informed substitution will be treated in these assessments, before and after post-2020 plans for the program.

The Government of Canada is currently working to explore ways to enhance the protection of workers from exposure to chemicals as well as exploring ways to apply informed substitution to support chemicals management. The Government of Canada will continue to engage stakeholders as this evolves.

The stakeholder notes that the public comment process needs to be more transparent and participatory.

The Government of Canada is committed to maintaining open and transparent assessment processes. Draft screening assessments are subject to a 60-day public comment period.  

Health Canada and Environment and Climate Change Canada carefully review all of the comments and information received, and changes are made to the risk assessment during its finalization, as appropriate.

While all comments are taken into consideration, the final content and conclusion of screening assessments remain the responsibility of Health Canada and Environment and Climate Change Canada.

Public comments are organized, consolidated, and summarized into a table and responses are prepared in clear, concise, and non-technical language. The summary of public comments and responses is published simultaneously with the final screening assessment on

The opportunity to provide input on the draft screening assessment is appreciated. Assistance is offered, should additional information be required.


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